Piezomechanik Dr. Lutz Pickelmann GmbH. Amplifiers D/A Converters Electronic HV-Switches for Piezoactuators

Transcription

1 Piezomechanik Dr. Lutz Pickelmann GmbH Amplifiers D/A Converters Electronic HV-Switches for Piezoactuators

2 Table of Contents Introduction Electro-Mechanical relations of piezoelectric actuators Practical aspects of dynamically operated piezoactuators Selection guide for amplifiers/supply electronics Special features Safety instructions Useful formulas Data of amplifiers SQV analog amplifiers Low voltage analog power amplifiers High voltage power amplifiers Bimorph amplifiers D/A Converters, Computer-Interfaces Accessories Amplifiers, D/A Converters, Electronic HV-Switches for Piezoactuators

3 Amplifiers, D/A Converters, Electronic HV-Switches for piezoactuators 1. Introduction Piezoelectrical actuators are innovative driving systems, which show increasing application potential for highly sophisticated driving/positioning tasks in a great variety of technological fields. The main areas of interest include the extreme positioning sensitivity, enabling such systems to handle dimensions in the atomic scale extreme force generation resulting for example in high acceleration rates during dynamic operation. For some applications no practicable alternative to piezoactuators exist Piezoelectric actuators are used for the ultraprecise positioning of components and mechanical setups ranging from low weight optical elements, up to heavy loads such as tooling machines. The newest scanning microscope technologies such as STMs, AFMs etc. require precise handling of probe tips with sub-nanometer precision, which can only done in a reasonable way by using piezomechanical elements. The high acceleration rates/short reaction times predestinate piezoelements for the control of fast processes in valve technology, fuel injection application, mechanical shaking excitation for test purposes with time periods/risetimes in the microseconds range. Piezoactuators are very attractive candidates for active vibration control and cancellation even in heavy and extended mechanical structures such as vehicles, airplanes, helicopters, ships. A special feature is the dual effect of piezoelectricity, which can be used both for sensing and actuating. Single element can therefore be used as smart transducers acting simultaneously as sensor and actuator. General considerations for electronic supplies for piezoactuators: In the simplest case a piezoactuator should move according to an external signal i.e. from a sinewave generator, or other source. In most cases, this original signal cannot be applied directly to the piezoactuator because voltage and power usually do not match the actuator s requirements. An amplifier has to be used to convert the signal to result in sufficient travel and dynamics of the actuator. This is an important aspect of actuator s application: The adaptation of a piezoelement to a distinct task is determined only in part by its mechanical properties and geometrical size. Equally important for the system s performance are the properties of the driving electronics. The same actuator can be used for completely different operating profiles depending only on the choice of the supply electronics: Slow cycling of an actuator requires only a small low power supply, whereas pulsed operation i.e. generating mechanical shocks, needs supplies with peakpowers in the kilowatt range. Computer control of actuators comprises an additional step: the computer data has to be converted by a D/A converter of sufficient speed and resolution, and the low voltage signal is than amplified to the actuator s requirements. signal generator elec. signal matching electronics piezo actuator mechan. reaction function generator feedback control electronic computer amplifier pulser Fig. 1: Schematic representation of an actuator system When designing a piezoactuated system the designer has to deal simultaneously with actuator and supply to get the optimum matching. A step-by-step definition whereby the actuator is first-chosen and then a subsequent selection of the supply may lead to costly and ineffective approaches. Amplifiers, D/A Converters, Electronic HV-Switches for Piezoactuators 3

4 2. Electro-Mechanical relations of piezoelectric actuators 2.1. Principle structures of piezoactuators Generally, all piezoelectric devices/transducers such as stacks, bimorphs, tubes can be described as a kind of capacitor with an electromechanically active dielectric medium: the PZT ceramic. Therefore, the electrical capacitance of such devices is an important operating parameter, especially when adapting the supply electronics for dynamic operation. The electrical capacitance of piezoactuators is shown in the data sheet. The strain within the PZT-medium is related to the internal electrical field strength when a voltage is applied to the element. An important consequence for practical consideration is, that the thinner the PZT-layers are, the lower can be the driving voltage. Furthermore the degree of lamination determines the electrical capacitance of piezoactuators. ceramic endfaces piezoceramic layers electrical connection Low voltage actuator types are operated with maximum voltages ranging from 50 V to 150 V, whereas the high voltage elements require hundreds of volts up to 1000 V (and more). For standard stacks the achieved maximum strain is about of the stack length. There exist highstrain stacks based on optimized PZT-materials showing a strain of 2 and more at fieldstrength of 3 kv/mm Polarity of piezoelectrical elements For piezoelectrical components an electrical polarity is usually defined. Piezoelectrical actuators e.g. stacks can only achieve their maximum response by applying the maximum voltage with correct polarity. Operation with counterpolarity voltage although possible is limited to remarkably lower ratings. A stack actuator shrinks under these conditions, increasing thereby to some extent the total moving range of the stack (see brochure piezomechanical stackactuators ). Bare piezostacks without casing are usually electrically insulated at the mechanical mounting points. They are supplied with pigtails showing the polarity by red(+) and black( ) insulation. Such elements can be combined therefore with positive or negative voltage supplies without difficulty. The situation changes, when actuators with casing are used. Here, the ground is defined by the coax-cable and therefore the polarity of the supply voltage is fixed. Piezoactuators with casing and the supply electronics from PIEZOMECHANIK are designed for positive polarity both for low voltage and high voltage actuators. This supports the easy combination of higher voltage actuators with lower voltage supplies, which is an important aspect for dynamic operation of actuators (see section 2.5.) Operating characteristics of piezoactuators The expansion of piezoelectric actuators is illustrated by voltage/expansion diagrams showing the well-known hysteresis (fig.3). Fig. 2a: Schematic representation of the capacitive layer structure of a piezostack rel. expansion rel. voltage Fig. 2b: Discretely built-up piezoelectric stack (high voltage type), external contact electrodes visible Fig. 3: Relative voltage/expansion diagram of a free running piezoactuator for different voltage reversal points 4 Amplifiers, D/A Converters, Electronic HV-Switches for Piezoactuators

5 Actuators are normally classified by the maximum applicable voltage for maximum stroke, and characterised as low voltage and high voltage types. For newcomers in piezotechnology, this sometimes gives the impression, that the voltage rating of an actuator is the sole criterion for selecting a proper electronic supply. This is however not correct. For any application of piezoactuators the electrical power/ current balance for charging and discharging the piezoactuator s capacitance has to be kept in mind. The variety of electrical supplies on offer is due mainly to the different power/current ratings of these devices. The charge/current balance during operation is related to the capacitive nature of actuators as shown below: Basic capacitor equation Q(t) = C U(t) C actuator s capacitance Q actual electrical charge U applied voltage Obviously the expansion of an actuator is also related to the quantity Q of electrical charge stored in the actuator s capacitance C, when a voltage U is applied. From this charge balance, the kinetic parameters of motion like speed and acceleration can be derived. These relations are the base for specifying the necessary current/power for distinct driving conditions. Actuator s position l ~ charge = Q(t). Speed v ~ current I = dq/dt = Q(t).. Acceleration b ~ variation of current = di/dt = Q(t) The generation for example of a sine-wave oscillation by a piezoactuator requires a defined supply current depending on actuator s capacitance and moving amplitude. Therefore an amplifier has to be selected for both criteria: voltage and current. Another consequence of the above is that, during a steady state of the actuator (constant position, constant force) no current is flowing, therefore no power is required. When a charged actuator is disconnected from the supply, it holds its position. This is an important difference to electromagnetic systems, where a constant position requires constant electrical power due to the sustaining current. The speed of an actuator cannot be increased infinitely even by very high currents, but is limited by the elastic properties of the stack. The maximum speed of stacked elements is in the range of a few m/sec. Because of the very limited moving range of piezoactuators the generation of above speeds requires high acceleration rates up to g. During operation of a piezodriven mechanical setup for highly dynamic application, it has to be verified that the mechanics coupled to the actuator shows a sufficiently high stiffness/ resonant frequency, otherwise the mechanics cannot follow actuator s motion and it is fruitless to optimize the drive for high speed/acceleration Peak current, average current Piezoactuators require electrical power/current only during dynamic operation. Expansion and contraction are characterized by charging/discharging currents. The short term available maximum peak current of a supply determines the minimum risetime/maximum speed of an actuator. Amplifiers of the series LE provide a special booster stage for high peak currents to get minimum risetimes. The average current of a supply determines the longterm cw-repetition rate of charging/discharging an actuator. For cw sine oscillation of an actuator, the required peak and average currents show a fixed ratio of approx. 3:1. Therefore, the selection of a supply to obtain a distinct cw-actuator frequency has to consider both, peak and average current data Power efficiency This section will lead on the first glance to the (surprising) result, that it is sometimes very reasonable and necessary to combine a high voltage actuator with a low voltage supply, where only a fraction of the actuator s maximum amplitude can be achieved. The reason for this strategy are twofold: optimizing power efficiency of a dynamically operated actuator system minimizing selfheating of a dynamically operated actuator. The basic idea is easily demonstrated with the following example, where the task requires the generation e.g. of a +/ 2,5 µm sine oscillation with a distinct frequency: The first example uses an actuator type PSt 500/5/5, where 500 V has to be applied to get the full stroke of 5 µm. A second example is to use the longer stack PSt 500/5/15 capable for a 15 µm motion at 500 V, showing an actuator s capacitance 3 times larger than in the 1st case. The important fact is, that with the longer stack only 150 V are needed to get the desired 5 µm stroke. Comparing the actuators energy content 1/2 CU 2 respectively, despite its larger capacitance the longer stack is favoured regarding power efficiency as only 1/3 of the power necessary to drive the shorter PSt 500/5/5 with full strain is required. It is obvious, that a 150 V system s total power efficiency is further improved by using a 150 V supply showing higher current output compared to a 500 V supply operated at reduced voltage rating. In the above described strategy, the problem of selfwarming under dynamic operating conditions is minimized by the reduced power input and by distribution of the dissipated energy over a larger volume/surface of the longer actuator. This is a powerful method to extend the application range of piezoactuators to high frequency cw-operation without the risk of overheating. This strategy of dynamic operation of actuators with reduced strain shows restrictions in other operating parameters: A longer stack has a lower stiffness and resonance, and it has to be determined, whether this is acceptable for a distinct application. Finally, an important contribution to the overall power efficiency of an actuator system is the use of recharger amplifiers (switched amplifiers). In most applications, piezoactuators display mainly a reactive load, where the energy content of a charged actuator flows back to the amplifier during the discharging cycle. Switched amplifiers RCV are able to recycle this energy with high efficiency, so that the needed linepower for a dynamically operated system has only to cover the (much smaller) active part of the power balance. This active power is drawn from the system as mechanical power or dissipated by the selfheating of the actuators. This technique shows the optimum of systems s overall power efficiency, and favours actuator applications, where high power levels are required e.g. for active vibration cancellation in heavy mechanical structures (vehicles, airplanes etc.) or anywhere, where the power consumption from the power supply is restricted i.e. battery operated systems. Power efficiency is defined as = (P r P al ) = (P r ) Pr = reactive power output from amplifier Pal = active power consumption from line An ideal amplifier without internal losses shows an efficiency 1. Amplifiers, D/A Converters, Electronic HV-Switches for Piezoactuators 5

6 2.6. Frequency response The performance of an amplifier is characterized by its frequency response, describing what cw-frequency/amplitude relations that can be achieved for a defined capacitive load. The achievable maximum frequencies of an actuator/supplysystem depend both on the output power of the supply, the capacitance of the driven actuator and the oscillation amplitude. To make the selection of an amplifier/actuator combination with respect to frequency response easier, some response curves for different capacitive loads are shown in the data sheet for distinct amplitudes. The response for intermediate capacitances are achieved by simple interpolation. An additional figure for an amplifier s performance is the achievable minimum risetime, which is tabulated for some load capacitances (see section 2.4.) Voltage stability, noise One of the most striking features of piezoactuators is their unlimited positioning sensitivity, which explains the sub-nanometer resolution for example scanning tunnel microscopes: A infinitely small voltage step Æ U is transformed into infinitely small mechanical shift Æ l. Ua = U o (1-e -t/rc ) R = internal load resistor of switch C = capacitance of external load (piezoactuator) Ua = voltage level at actuator Uo = supply voltage from internal charge storing capacitor For the operation of the HVP s 3 time constants have to be distinguished: Switching time of output transistors: order of magnitude: 1 µsec defines the minimum electrical pulsewidth Time constant RC: Defines the signal/voltage risetime at the actuator. Pulsewidths shorter RC lead to a partial charging of the actuator and thereby to intermediate positions between low and high Period time of actuator/actuated system (fig. 4.): This time constant defines the minimum mechanical rise/fall-time of the system. To excite the minimum mechanical risetime Tp of an actuator, the RC time constants of the pulsersystem has to be shorter than Tp. Æ l = l Æ U/U l = actuator s shift for signal voltage U Neglecting external influences, the positioning sensitivity of an actuating system is limited only by the stability of the electronic supply (noise). Example: The amplifiers SQV 150 show a noise of approx. 1 mv equivalent to a S/N ratio of about A 100 µm actuator such as the PSt 150/7/100 VS 12 operated with the SQV 150 shows a variation in position of only 1 nm Pulsed operation of piezoactuators An important feature of piezoactuators is their capability to produce extreme forces and acceleration rates, which can be used for fast switching of valves or to produce mechanical shocks. In such cases, the actuator should switch in as short time as possible between 2 distinct levels, whereas the exact motion profile between these levels is not important. The minimum risetime of an actuator can derived from its elastic properties: A short electrical pulse excites the resonant oscillation of the actuator and the minimum risetime Tp can be estimated by Tp Å Tr/3 Tr = period time of actuator s resonance Tp = minimum risetime in pulsed operation Example: A systems s resonant frequency of 3 khz results in a minimum mechanical risetime of about 100 µsec. A simple calculation shows, that above shown pulse generation requires peak powers up to the kilowatts range with currents of 10 to 100 Amperes. In these cases it is reasonable not to use analogue amplifiers but electronic pulse switches. The common design of a HV-pulse generator consists of a high voltage supply, which continuously charges at a defined low power (i.e. 50 Watt) a large internal charge storing capacitor. This capacitor delivers short term the very high currents to the external piezoactuator capacitance, when it is switched by transistors via a load resistor R. The load resistor R acts as current limiter to avoid electrical overpowering and defines the time constant RC of the pulser (rise/fall-time) according the well-known relation voltage step Fig. 4: Excitation of a mechanical pulse by a voltage step 0V/Uo; lo final static position of actuator 2.9. Feedback controlled systems Piezoelectric actuators are well-suited for setting up electronically controlled systems for fast and precise handling of mechanical parameters such as position, speed and force. Because of the hysteretic and slightly nonlinear behaviour of piezoactuators, and nonpredictable external influences, this has to be done by feedback control. A sufficiently fast and sensitive transducer picks up the actual position or other parameter of interest and the signal is evaluated by feedback control electronics, producing the control signal for the actuator. The overall efficiency e.g. precision of such a system is determined by the transducer and electronics and not by the actuator. The high performance of feedback controlled systems is demonstrated by the atomic resolution of the scanning tunnel microscopes (STMs). 6 Amplifiers, D/A Converters, Electronic HV-Switches for Piezoactuators

7 A further application is the active stabilization of mechanical arrangements e.g. laser resonators against misalignment due to thermal drifts or mechanical shocks (see feedback controlled stabilization PiStab 2 ). 3. Practical aspects of dynamically operated piezoactuators 3.1. Preloading, reset mechanisms Piezoceramic is sensitive to tensile stress, it shows a damage strain of only 1. Note, that this tensile stress can be created externally and also internally by dynamic operation. This fact is easily seen in Fig 4/sec. 2.8., where the application of an electric pulse leads to overshooting of the actuator relative to the steady state position. This overshooting can cause tensile stress and thereby damage to the actuator when the relevant forces are not compensated by other means. To prevent damage by tensile forces the following strategies are commonly applied: passive preloading/reset of actuators This technique is mostly applied to stack actuators: An elastic spring compresses the piezostack with a defined force shown in fig. 5a, b. A preloaded stack is less sensitive to externally applied tensile stress for several reasons, i.e. a reduction in stacklength is achieved by the preload force. A tilting mirror surface piezostack prestress/reset spring Fig. 5a: Mirror tilter with passive prestress/reset prestress spring piezostack Fig. 5b: Linear stackactuator with passive prestress/reset Amplifiers, D/A Converters, Electronic HV-Switches for Piezoactuators 7

8 real tensile stress is acting on the ceramic only, when the external force lengthens the stack beyond the original (loadfree) state. Furthermore, the elastic counterforce slows down the moving mass in the overshoot phase during dynamic operation. So, the applied preload force can be chosen according the tilting mirror surface 3.2. Selfheating Another aspect of dynamically operating piezoactuators is their selfheating. Due to the ferroelectric nature of PZT ceramics, the electrical operating power transferred to the actuator is partially dissipated as heat. For example an actuator PSt 150/5/15 with full amplitude operation heats up to the operating temperature limit at about 600 Hz. Higher temperatures will shorten an actuators lifetime. A further increase of frequency therefore requires cooling or an equivalent reduction of amplitude (see sec. 2.5). Simple surface cooling results in limited success for large volume actuators, because PZT ceramics have poor thermal conductivity. Furthermore measuring the actuator s temperature on its surface does not reflect the internal conditions. A good parameter for checking the volume temperature is the temperature dependence of the electrical capacitance of the actuator leading to a shift of the current balance. Fig. 6a: Mirror tilter with active (push-pull) reset piezostack piezostack Fig. 7: Temperature dependence of the electrical capacitance of a typical piezoactuator (relative to capacitance at roomtemperature) Fig. 6b: Linear push-pull arrangement of piezostacks for active reset simple mass acceleration law to accommodate the accelerated masses within the desired short rise/fall-times. The standard preloading VS of PIEZOMECHANIK actuators cover a wide range of applications. It is possible to apply higher preload forces, which can be supplied on request or can be applied externally (see brochure piezomechanical stackactuators ). active reset (push-pull mode, antagonistic configuration) A more sophisticated reset mechanism for compensating dynamic forces is the arrangement with two complementary working actuators shown in fig. 6a, b. The advantages include a symmetric force balance for both directions of motion, and higher resonance frequencies compared with passive preloading. 8 Amplifiers, D/A Converters, Electronic HV-Switches for Piezoactuators

9 3.3. Vibration control, acoustical noise Every dynamic excitation of a piezoactuator attached to a mechanical structure acts back on this structure. Pulsed or oscillating actuators generate vibrations in the mechanical structure. In case of a resonance a large amplitude response can emerge even for small excitation levels, which can interfere with the regular function of the structure. Therefore, dynamically operated structure have to be designed for sufficiently large resonant frequencies, and include sufficient damping to avoid these unwanted side effects at the driving frequency. Vibration suppression can be done in passive or active ways. An example for active pulse compensation is shown in fig. 8, where a counteracting piezostack compensates for the repulse of the original stack, e.g. shifting a mirror. Generally, piezoelements are powerful tools for vibration control, both for generating vibrations (shakers) and for cancellation (active vibration isolation and damping). Active com- 4. Selection guide for amplifiers/supply electronics PIEZOMECHANIK offers a wide range of supply electronics to obtain the optimum solution for different applications of piezoactuated systems. For specifying dynamically operated actuator/amplifier systems the power/current requirements are determined by the actuator s capacitance. Note that the actuator s capacitance can vary up to 50% (e.g. see section 3.2.) leading to correspondingly elevated power/current ratings. The supply electronics and actuators from PIEZO- MECHANIK are set to positive polarity for both high voltage and low voltage components, so that widest compatibility is achieved e.g. for power efficient arrangements according sec On request PIEZOMECHANIK supplies piezocomponents for negative operating polarity. mirror static suspension piezostack piezostack compensating mass 4.1. SQV amplifiers The range of SQV amplifiers comprises the 3 main voltage ranges, where piezoactuators are offered namely 150 V (+200 V), 500 V and 1000 V. The output power is a few watts, which is sufficient for most applications. Smaller volume actuators can be operated even with higher dynamic/frequencies. SQV amplifiers show low noise and are therefore best suited for positioning tasks with highest positioning sensitivity. SQV amplifiers are available as 3-channel versions e.g. for optomechanical xyz adjusters. impulse LE amplifiers LE amplifiers are used, when the power/current requirements cannot be covered by the SQV amplifiers. The LE series includes current boosters for optimum system power efficiency, when e.g. a high frequency sinoidal oscillation has to be excited, or to get short rise/fall-times for a rectangular signal. The LE amplifiers are available for power levels up to hundreds of watts. Due to these elevated power levels, selfheating of actuators according sec should be considered. Fig. 8: Mechanical impulse compensation pensation can be done in feedback controlled systems, where a transducer detects an incoming vibration, and excites an antivibration with proper amplitude and phase relation via an actuator. From ergonomic aspects, it must be kept in mind, that actuator vibrations can produce acoustical noise which may be very uncomfortable for the operator RCV recharging amplifiers The RCV switched amplifiers are designed for driving large volume/large capacitance piezoactuators with high currents and powers up to the kilowatt range beyond the levels of the LE analog amplifiers. This situation occurs for example with the active excitation and cancellation of vibrations in heavy mechanical structures e.g. vehicles, airplanes etc. Because the design of RCV amplifiers has to be adapted to some extent to the operated load, there are no standardized devices. In principle, RCV amplifiers can also be designed for lower power ratings. Please contact us for details Bipolar amplifiers Usually piezoactuators such as stacks are operated unipolar or asymmetrically bipolar to get maximum displacement. Some applications exist, where piezoelements are operated symmetrically bipolar, but to avoid depolarization of the PZT ceramic, the electrical field strength and thereby actuator s efficiency has to be held sufficiently low. Reasons for bipolar operation include simple electrical driving conditions e.g. of piezobenders (bimorphs), shearmode actuators or enhancement of stack actuators lifetime e.g. within feedback control loops for position stabilization. In this case, the middle position is defined by 0 V, no offset is required for symmetric positioning range. This leads to long- Amplifiers, D/A Converters, Electronic HV-Switches for Piezoactuators 9

10 term low electrical fields preventing materials degradation by charge carrier diffusion. Nevertheless, bipolar amplifiers can also generate unipolar or asymmetric output by applying a proper signal BMT, AGV antagonistic amplifiers The AGV/BMT amplifiers are designed to drive push-pull (antagonistic) stack arrangements or piezobenders ( Bimorphs ) described in section 3.1. By electrical preloading, the full operating range of the ceramics can be used without the risk of depolarization which may happen during simple bipolar operation. The modulation of the antagonistic piezoelements is done by a single driving signal, complementary action is achieved by different static offsets shown in fig. 9a, b, c. This strategy ensures forced synchronization of motion of the 2 elements even under high dynamic driving conditions. For an antagonistic setup, the actuators have to show potential free design, meaning that the operating ground of the AGV/BMT Fig. 9a: Push-pull-stack arrangement with schematic electronic supply configuration Fig. 9b: Operation of a parallel-bimorph with electrical preloading AGV/BMT amplifier piezoelements has to be separated from general ground of the arrangement HVP high voltage switches for pulse operation HV-pulse generators are used when currents beyond the level of common amplifiers are necessary and where a steady movement of an actuator is not required, but only defined levels should be set within short times or where mechanical shocks have to be produced. The HVP high voltage pulse generators from PIEZOMECHA- NIK show some interesting features enabling the user to drive piezoactuators in a more sophisticated way than the simple high, low procedure with common switches. Beside the levels charging = high, discharging = low there exist a third level neutral, where the output is set to high resistance, so that the charge content (= position) of the actuator is kept constant. Thus the system can be set and held in intermediate positions. This is achieved by applying signal pulses with width less the time constant RC of the system, leading to only a partial charging of the actuator s capacitance corresponding an intermediate position. A general approach for pulsed actuator operation is not to oversize current specs for a distinct application, because too powerful pulses may cause unnecessary mechanical and electrical stress to the system. On the other hand the mechanical reaction time cannot be infinitely improved by increasing the pulsepower (see sec. 2.8.) Computer interfaces For computer control of piezoactuators a lot of designs and arrangements for interfacing exist. The selection of the proper interface for a distinct application depends on the basic hardware/software the user can provide, and the flexibility he wants to achieve with his setup. Computer with internal D/A converter: computer output is an analog signal The supplies low voltage analog signal output (e.g. 0 V to +10 V) is applied directly to the analog amplifiers etc. from PIEZOMECHANIK. HV-PC-card: The computer output is an analog signal. This card is inserted in the computer and produces immediately an analog-hv-signal for voltages up to +150 V or +500 V also in multichannel configuration. The power range is similar to the SQV or lower power LE amplifiers. This signal is directly applicable to the piezoactuator. Space saving configuration. External D/A Converters: The computer output is digital data. In this case, the digital data has to be transferred via a serial or parallel interface similar to any other peripheric device for a computer e.g. a printer. The data is then converted by a D/A stage into an analog signal with subsequent amplification by usual analog amplifiers. The low voltage D/A converting unit can be a stand-alone device, or can be integrated to the amplifiers cabinet. In all these cases, the analog functions of the amplifiers remain active e.g. a manual setting of an offset voltage is possible, which is useful for adjusting setups before starting computer control. Multichannel systems are available. AGV/BMT amplifier Fig. 9c: Equivalent circuit to piezoactuator arrangements 9a, 9b 10 Amplifiers, D/A Converters, Electronic HV-Switches for Piezoactuators

11 5. Special features Analog amplifiers from PIEZOMECHANIK show some special features, which are very useful for the operation of piezoactuators: Offset The amplifiers are provided with a potentiometer where a DC-output voltage can be manually set over the full operating range. In this mode, the amplifier can be used as an adjustable voltage supply without the application of an external signal. When an external signal is amplified, the Offset voltage is superimposed automatically. This is useful, when the signal generator produces only bipolar signals which have to be shifted to get the unipolar signal required to drive piezoelements effectively. Amplitude Using this potentiometer, the input signal can be adapted to the working range of the amplifier. It is possible to use signal levels 5 V as well as 10 V (e.g. from standard D/A converting units). Current booster Higher power amplifiers such as the LE types are provided with a current booster, which enable the amplifier to produce a much higher current (for a limited time) than the long term average current. In this mode, the amplifier is optimized for high power efficiency when a capacitive load such as a piezoactuator is operated. The current booster reduces further the risetime, when rectangular signals are applied. For these amplifiers the risetimes for a variety of loads are tabulated in the datasheet. 6. Safety Instructions During operation of piezoactuators voltages and electrical currents are present which may be harmful to the operator Installation and operation of actuators and electronics supplies must be carried out by authorized personal only All electrical installation of electric supplies, cables and connectors must be carried out according to standard safety regulations Piezoactuators can show large electrical capacitances, and charged actuators can store electrical charge at high voltage levels, even for long times after being disconnected from the power supply. When large volume actuators are not in use, discharge them carefully, and hold them shortcircuited. Piezoactuators can generate electrical charge at high voltage levels, when varying load or temperature is acting on actuators with open leads. When large volume actuators are not in use, discharge them carefully, and hold them shortcircuited. Take care when opening amplifiers and pulsegenerators. High voltage levels can be held for a long time after disconnecting the devices from line due to large capacitance internal capacitors. If these devices must be opened, wait at least 15 minutes after disconnecting them from line. Complete discharge of the internal capacitors has to be ensured by shortcircuiting via a proper resistor. Monitor output The average output voltage is shown on the front display of the amplifiers. Realtime signal monitoring is done by the Monitor -output, which represents the actual power output status by a 1:100 ratio low power signal. The monitor-output is used for realtime representation via an oscilloscope. Further it can be used as a signal source for any control arrangement (feedback control, voltage limitation), where information about the current status of the actuator is needed. Amplifiers, D/A Converters, Electronic HV-Switches for Piezoactuators 11

12 7. Useful formulas Notice: the following relations are dealing with ideal capacitors, where the capacitance is invariable under the driving conditions. But piezoactuators show to some extent deviations from this ideal behaviour due to their ferroelectric nature. Their capacitances depend on electrical fieldstrength (voltage level), temperature and other parameters and may exceed the nominal values by 50%, which are stated in the data sheet. General: capacitor relation C = Q/U charging/discharging current I(t) = C du/dt Average current l, t repetition rate, U o maximum voltage Sinuoidal excitation Unipolar signal Current U o f C max. supply voltage frequency actuators capacitance Peak current I a = U o C/t U(t) = U o /2 (1-cos 2 p ft) I(t) = U o C p f sin (2 p ft) I p = p U max C f Pulse excitation Operating voltage Ua(t) of actuator: Charging current Ic(t) Ua(t) = U o (1-e t/rc ) Ic(t) = (U o -Ua(t))/R R load resistor of pulse generator (see sec.2.8.) Peak current at pulse onset: Average current Ic max = U o /R I a = U o Cw w repetition rate, U o supply voltage Power balance Energy content E of a charged capacitance E = 1/2 CU o 2 Average current I a = U max C f Average power consumption P A during cycling with repetition rate w Peak current exceeds average current by factor p. Current booster needed for optimum power efficiency. Symmetric triangular signal Peak current I p = U max Cf P A = 1/2 CU o2 w Dissipated power (selfheating problem) During the charging/discharging cycles, the transferred power is partially dissipated into heat according P dis = tand CU o2 w Average current I a = U max Cf tand dissipation factor 5 10% of total power with common PZT actuator ceramics No current booster necessary. 12 Amplifiers, D/A Converters, Electronic HV-Switches for Piezoactuators

13 SQV analog amplifiers (low voltage/high voltage types) SQV 1/150 single channel amplifier +150 V output Special features: see chapter 5. Potentiometer Offset Potentiometer Amplitude Input Input: +/ 5 V (+/ 10 V see chapter 5) Input resistance: 10 kohm Input connector: BNC Output: Voltage range: 10 V thru +150 V Max. peak current/average current: approx. 60 ma Gain: 30 Noise: approx. 1 mvpp with capacitive load (actuator) Connector: BNC Display: LCD, 3 digits Dimensions: WxDxH 165x210x70 mm Weight: approx. 1.7 kg Frequency response open output: U max/2 >20 khz Risetimes: (for square wave input signal) Load risetime capacitance to 100 V/150 V 22 µf 40 msec /80 msec 4.2 µf 8 msec /18 msec 1.2 µf 2 msec / 5 msec 330 nf 0.5 msec /1.2 msec SQV 3/150 triple channel device 3 independent channels Performance data /channel equiv. SQV 1/150 LC-voltage display, channel selection by dial Dimensions: WxDxH 215x210x70 Weight: 2.4 kg Option: Amplifier for 200 V output: on request Amplifiers, D/A Converters, Electronic HV-Switches for Piezoactuators 13

14 SQV 1/500 single channel amplifier +500 V output Special features: see chapter 5. Potentiometer Offset Potentiometer Amplitude Input Input: +/ 5 V (+/ 10 V see chapter 5) Input resistance: 10 kohm Input connector: BNC Output: Voltage range: 0 V thru +500 V Max. peak current/average current: approx. 20 ma Gain: 100 Noise: approx. 1 mvpp with capacitive load (actuator) Connector: BNC Display: LCD, 3 digits Dimensions: WxDxH 165x210x70 mm Weight: approx. 1.7 kg Frequency response open output: U max/2 >20 khz Risetimes: (for square wave input signal) Load risetime capacitance to 300 V/500 V 1.2 µf 20 msec / 42 msec 660 nf 10 msec / 22 msec 330 nf 5 msec / 11 msec 100 nf 1.5 msec / 3.5 msec 30 nf 0.5 msec / 1.2 msec SQV 3/500 triple channel device 3 independent channels Performance data /channel equiv. SQV 1/500 LC-voltage display, channel selection by dial Dimensions: WxDxH 215x210x70 Weight: 2.4 kg 14 Amplifiers, D/A Converters, Electronic HV-Switches for Piezoactuators

15 SQV 1/1000 single channel amplifier V output Special features: see chapter 5. Potentiometer Offset Potentiometer Amplitude Input Input: +/ 5 V (+/ 10 V see chapter 5) Input resistance: 10 kohm Input connector: BNC Output: Voltage range: 0 V thru V Max. peak current/average current: approx. 10 ma Gain: 200 Connector: LEMOSA OS.250 (BNC adaptor available) Noise: approx. 5 mvpp with capacitive load (actuator) Display: LCD, 3 digits Dimensions: WxDxH 165x210x70 mm Weight: approx. 1.7 kg Frequency response open output U max/2 >20 khz Risetimes: (for square wave input signal) Load risetime capacitance to 700 V/1000 V 1.2 µf 70 msec /140 msec 330 nf 20 msec /35 msec 100 nf 6 msec /10 msec 30 nf 1.8 msec / 3 msec SQV 3/1000 triple channel device 3 independent channels Performance data /channel equiv. SQV 1/1000 LC-voltage display, channel selection by dial Dimensions: WxDxH 255x290x115 Weight: 3.5 kg Amplifiers, D/A Converters, Electronic HV-Switches for Piezoactuators 15

16 Low voltage analog power amplifiers LE 150/025 single channel amplifier +150 V output Special features: see chapter 5. Potentiometer Offset, Amplitude, Current Booster, Monitor output Input Input: +/ 5 V (+/ 10 V see chapter 5) Input resistance: 10 kohm Input connector: BNC Output: Voltage range: 10 V thru +150 V Max. peak current: approx. 250 ma Max. average current: approx. 70 ma Gain: 30 Noise: approx. 15 mvpp Connector: BNC Display: LCD, 3 digits Dimensions: WxDxH 185x330x150 mm Weight: approx. 4 kg Frequency response open output: U max/2 >20 khz Risetimes: (for square wave input signal) Load risetime capacitance to 100 V/150 V 22 µf 10 msec/50 msec 4 µf 2 msec/ 3 msec 1.2 µf 0.5 msec/ 0.8 msec 330 nf 120 µsec/180 µsec Options: Multichannel arrangements: on request Amplifier for 200 V output: on request Computer interfaces: Optionally, the amplifier LE 150/025 can be equipped by a serial or parallel (CENTRONIX) computer interface (designation as LE 150/025-S or/-p respectively) for digital control by a fast data transfer and D/A conversion. Up to 3 channels can be operated simultaneously. All analog functions of the amplifier remain active. By using offset the amplified signal can be superimposed by a DC-voltage and the operating voltage range can be varied by amplitude for easy adaption to a distinct application. The resolution is 12 bit. Order code LE 150/025 LE 150/025-S LE 150/025-P analog amplifier with additional serial interface with additional parallel interface 16 Amplifiers, D/A Converters, Electronic HV-Switches for Piezoactuators

17 LE 150/100 single channel power amplifier +150 V output Special features: see chapter 5 Potentiometer Offset, Amplitude, Current Booster, Monitor output Input Input: +/ 5 V (+/ 10 V) Input resistance: 10 kohm Input connector: BNC Output: Voltage range: 0 V thru +150 V Max. peak current: approx ma Max. average current: approx. 350 ma Gain: 30 Connector: BNC Noise: approx. 15 mvpp Display: LCD, 3 digits Dimensions: WxDxH 330x260xl55 Weight: approx. 7 kg Frequency response open output: Risetimes: (for square wave input signal) Load risetime capacitance to 100 V/150 V 47 µf 3 msec/7 msec 22 µf 1.8 msec/4 msec 4 µf 330 µsec/500 µsec 1.2 µf 90 µsec/130 µsec 330 nf 20 µsec/35 µsec Options: Multichannel arrangements: on request amplifier for 200 V output: on request Computer interfaces: Optionally, the amplifier LE 150/100 can be equipped by a serial or parallel (CENTRONIX) computer interface (designation as LE 150/100-S or/-p respectively) for digital control by a fast data transfer and D/A conversion. Up to 3 channels can be operated simultaneously. All analog functions of the amplifier remain active. By using offset the amplified signal can be superimposed by a DC-voltage and the operating voltage range can be varied by amplitude for easy adaption to a distinct application. The resolution is 12 bit. Order code LE 150/100 LE 150/100-S LE 150/100-P analog amplifier with additional serial interface with additional parallel interface Amplifiers, D/A Converters, Electronic HV-Switches for Piezoactuators 17

18 Amplifier system LE 150/200 (formerly LE 150/2) Modular arrangement of up to 3 independent channels. For operation of large volume/high capacitance piezoactuators. The technical data are similar to the LE 150/100 amplifier except for higher peak current. Technical data valid per channel. Special features: see chapter 5 Potentiometer Offset, Amplitude, Current Booster Input Input: +/ 5 V (+/ 10 V see chapter 5) Input resistance: 10 kohm Input connector: BNC Output: Voltage range: 10 V thru +150 V Max. peak current: 2000 ma Max. average current: approx. 400 ma Gain: 30 Connector: BNC Noise: approx. 50 mvpp Display: LCD, 3 digits Dimensions: Single channel version LE 150/200-1 BxWxD 340x350x180 Weight: 10 kg Frequency response open output: Options: Multichannel arrangements: on request Amplifier for 200 V output: on request Risetimes: (for square wave input signal) Load risetime capacitance to 100 V/150 V 47 µf 2.4 msec/4 msec 22 µf 1.2 msec/2 msec 4 µf 240 µsec/400 µsec 1.2 µf 60 µsec/150 µsec 330 µf 15 µsec/40 µsec Computer interface: The amplifier system LE 150/200 is available with a computer interface module for both types of data transfer serial and parallel (CENTRONIX). Up to 3 channels can be operated simultaneously. All analog functions of the amplifier modules remain active. By offset the amplified digital signal can be superimposed by a DC-voltage and the operating voltage range can be varied by amplitude for easy adaption to a distinct application. The resolution is 12 bit. Order code: D/A-LE Analog amplifier LE 150/300 Single channel power amplifier Output: Voltage range 10 V thru +150 V Max. peak current: 3 A Max. average current: 1 A Analog amplifier LE 150/100 bp Bipolar amplifier system with +/ 150 V output. Voltage range: 150 V thru +150 V Max. peak current: 1000 ma Max. average current: 200 ma 18 Amplifiers, D/A Converters, Electronic HV-Switches for Piezoactuators

19 High voltage power amplifiers LE 430/015 single channel amplifier +430 V output Special features: see chapter 5 Potentiometer Offset, Amplitude, Current Booster, Monitor output Input Input: +/ 5 V (+/ 10 V see chapter 5) Input resistance: 10 kohm Input connector: BNC Output: Voltage range: 0 V thru +430 V Max. peak current: 150 ma Max. average current: approx. 35 ma Gain: 85 Noise: approx. 50 mvpp Connector: LEMOSA 0S.250 (BNC adaptor available) Display: LCD, 3 digits Dimensions: WxDxH 185x330x150 mm Weight: approx. 4 kg Frequency response open output: U max/2 >20 khz Risetimes: (for square wave input signal) Load risetime capacitance to 300 V/430 V 1.2 uf 2 msec/3 msec 660 nf 1 msec/1.4 msec 330 nf 0.5 msec/0.7 msec 100 nf 180 µsec/250 µsec 30 nf 70 µsec/l00 µsec Options: Multichannel arrangements: on request Computer interfaces: Optionally, the amplifier LE 430/015 can be equipped by a serial or parallel (CENTRONIX) computer interface (designation as LE 430/015-S or/-p respectively) for digital control by a fast data transfer and D/A conversion. Up to 3 channels can be operated simultaneously. All analog functions of the amplifier remain active. By offset the amplified signal can be superimposed by a DC-voltage and the operating voltage range can be varied by amplitude for easy adaption to a distinct application. The resolution is 12 bit. Order code: LE 430/015 LE 430/015-S LE 430/015-P analog amplifier with additional serial interface with additional parallel interface Amplifiers, D/A Converters, Electronic HV-Switches for Piezoactuators 19

20 LE 1000/035 single channel amplifier V output Special features: see chapter 5 Potentiometer Offset, Amplitude, Current Booster, Monitor output Input Input: +/ 5 V (+/ 10 V see chapter 5) Input resistance: 10 kohm Input connector: BNC Output: Voltage range: 0 V thru V Max. peak current: 350 ma Max. average current: approx. 100 ma Gain: 200 Noise: approx. 50 mvpp Connector: LEMOSA 0S.250 (BNC adaptor available) Display: LCD, 3 digits Dimensions: WxDxH 260x340x160 mm Weight: approx. 4.5 kg Frequency response open output: Risetimes: (for square wave input signal) Load risetime capacitance to 1000 V 200 nf approx. 0.5 msec 1 µf 3 msec 5 µf 15 msec Options: Multichannel arrangements: on request Unipolar amplifier LE 500/070 Output voltage 0 V thru +500 V, peak current appr. 700 ma, mean current approx. 250 ma Bipolar amplifier LE 500/035 bip Output voltage +/ 500 V, peak current approx. 350 ma, mean current approx. 100 ma 20 Amplifiers, D/A Converters, Electronic HV-Switches for Piezoactuators

21 LE 1000/100 single channel amplifier V output Special features: see chapter 5 Potentiometer Offset, Amplitude, Current Booster, Monitor output Input Input: +/ 5 V (+/ 10 V see chapter 5.) Input resistance: 10 kohm Input connector: BNC Output: Voltage range: 0 V thru V Max. peak current: 1000 ma Max. average current: approx. 300 ma Gain: 200 Noise: approx. 50 mvpp Connector: LEMOSA 0S.250 (BNC adaptor available) Display: LCD, 3 digits Dimensions: WxDxH 160x380x210 mm Weight: approx. 5.5 kg Frequency response open output: Risetimes: (for square wave input signal) Load risetime capacitance to 1000 V 200 nf approx. 0.2 msec 1 µf 1 msec 5 µf 5 msec Options: Multichannel arrangements: on request Unipolar amplifier LE 500/200 Output voltage 0 V thru +500 V, peak current appr ma, mean current approx. 700 ma Bipolar amplifier LE 500/100 bip Output voltage +/ 500 V, peak current approx ma, mean current approx. 300 ma Amplifiers, D/A Converters, Electronic HV-Switches for Piezoactuators 21

22 High efficiency power recharger amplifiers RCV The basic philosophy of switches recharging amplifiers is described in sec PIEZOMECHANIK offers recharging amplifiers for average powers of 500 Watts up to the kwatt range. Because recharging amplifiers have to be adapted to some extent to the capacitance of the actuator and the desired driving conditions, a detailed offer is made after receipt of specifications and requirements. Generally, the device can be matched to an application within the below stated limits: Voltage range: 600 V to +600 V Peak currents: up to 10 A Peak power: 2 kw Average power: 500 W Ripple/noise by switching mode: approx. 200 mv Power efficiency with loss-free capacitive load: > 95 % (definition see sec. 2.5.) Example: E.g. RCV amplifiers have been developed for active vibration cancellation showing following data Load capacitance: approx. 20 µf Operating frequency: up to 400 Hz Voltage range: +/ 200 V Max. peak current: 10 A Risetime for a 200 V voltage step at 5 µf load: 100 µsec. If you are thinking about recharging amplifiers for your application, contact us. 22 Amplifiers, D/A Converters, Electronic HV-Switches for Piezoactuators

23 Power pulsers HVP (see sec. 2.8.) The HVP switches/pulsers show 3 operational levels positive square wave = charging of actuator negative square wave = discharging of actuator zero level = output neutral: no charge transfer = steady state of actuator. The internal supply (source) voltage of the HV pulser can be set by a potentiometer and is shown on the front panel LC display. The specified peak currents are achieved for max. supply voltage setting. General data Input: signal high = charging of actuator: > +3 V signal low = discharging of actuator: < 3 V signal neutral no charge transfer: 0 V Connector: BNC Output: Voltage/currents see listing Average power: 50 Watts Minimum pulse width: approx. 3 µsec Repetition rate: up to 50 khz Connectors: LEMOSA 0S.250 and 2 banana pin plugs Display: 3 1 / 2 digit LCD Dimensions: WxDxH 260x340x160 Weight: 4.5 kg Types max. voltage peak Load time constant RC/ currents resistors for load capacitance V A Ohms HVP 200/ µsec / 10 µf HVP 200/ µsec / 10 µf HVP 500/ µsec / 1 µf HVP 500/ µsec / 1 µf HVP 500/ µsec / 1 µf HVP 1000/ µsec /0.5 µf HVP 1000/ µsec /0.5 µf HVP 1000/ µsec /0.5 µf Options: HVP can be supplied for altered source voltages altered current ratings higher average powers Power resistor box PRB: The peak current of a HVP switch can be reduced by using the external resistor box PRB e.g. for adaption to a lower capacitance actuator. It contains 3 power resistors of different ratings and is connected between HV-switch and actuator. The resulting peak current is determined by the total resistance of the arrangement: internal resistor of switch (see listing) + the external resistor. The box is equipped with one input coax cable/lemosa 0S.250 plug. Each resistor has its individual output connector and is selected thereby. PRB I: PRB II: 1 resistor 2 Ohms 1 resistor 5 Ohms 1 resistor 10 Ohms 1 resistor 10 Ohms 1 resistor 20 Ohms 1 resistor 50 Ohms Input/output connectors: LEMOSA 0S.250 (BNC adaptors available). Amplifiers, D/A Converters, Electronic HV-Switches for Piezoactuators 23

24 Amplifiers for push-pull actuator configuration Bimorph amplifiers (see sec. 3.1./4.5) BMT 60 bimorph amplifier For the philosophy of driving multilayer bimorph actuators under electrically preloaded conditions check brochure piezoelectric bending elements. In this case, the ceramic is operated with permanently forward polarized voltage and thereby prevented from depolarization, so the maximum mechanical performance is achieved. The bimorph amplifier BMT 60 has been designed to drive multilayer-benders elements in the above described optimum way with high dynamics. Because of the analogy of the electrical operation of antagonistic piezostacks configuration and bimorphs, the BMT 60 can also drive complementary acting push-pull stack arrangements (sec. 3.1.) Special features: Potentiometer Offset Potentiometer Amplitude Monitor output Input Input: +/ 5 V (+/ 10 V see chapter 5) Input resistance: 100 kohm Input connector: BNC Output: 3 pole connector for ground 0 V, fix voltage U F +60 V Signal voltage U S 0 V thru +60 V Max. peak current: 280 ma in each branch Gain: 12 Noise: approx. 20 mvpp output connector Connector: 3 pole connector LEMOSA (1 m cable with suitable plug is included) Display: LCD, 3 digits Dimensions: WxDxH 165x210x70 mm Weight: approx. 1.4 kg 24 Amplifiers, D/A Converters, Electronic HV-Switches for Piezoactuators

25 AGV 150/013 amplifier This amplifier has been designed to operate low voltage stack push-pull configurations in the electrically preloaded mode (see sec. 4.5.). Because of the analogy in the electrical driving scheme, also bimorph elements can be operated by this amplifier with high efficiency. Special features: Potentiometer Offset, Amplitude, Current Booster, Monitor output Input Input: +/ 5 V (+/ 10 V see chapter 5) Input resistance: 100 kohm Input connector: BNC Output: 3 pole connector for ground 0 V, fix voltage U F +150 V Signal voltage U S 0 V thru +150 V Max. peak current: 130 ma in each branch Max. average current: 70 ma in each branch Gain: 30 Connector: 3 pole connector LEMOSA (1 m cable with suitable plug is included) Noise: approx. 20 mvpp Display: LCD, 3 digits Dimensions: WxDxH 185x330x150 mm Weight: approx. 4 kg output connector AGV 430/08 amplifier This amplifier has been designed to operate high voltage stack push-pull configurations in the electrically preloaded mode (see sec. 4.5.). Because of the analogy in the electrical driving scheme, also bimorph elements can be operated by this amplifier with high efficiency. Special features: Potentiometer Offset, Amplitude, Current Booster, Monitor output Input Input: +/ 5 V (+/ 10 V see chapter 5) Input resistance: 100 kohm Input connector: BNC Output: 3 pole connector for ground 0 V, fix voltage U F +430 V Signal voltage U S 0 V thru +430 V Max. peak current: 80 ma in each branch Max. average current: 35 ma in each branch Gain: 85 Noise: approx. 50 mvpp Connector: 3 pole connector LEMOSA (1 m cable with suitable plug included) Display: LCD, 3 digits Dimensions: WxDxH 185x330x150 mm Weight: 4.5 kg output connector Amplifiers, D/A Converters, Electronic HV-Switches for Piezoactuators 25

26 D/A converters, Computer-Interfaces The optionally available interfaces which are integrated to amplifiers are described in the corresponding data sheet for the amplifiers e.g. LE 150/025-S. This basic range of interfaces is completed by the units described in the following section 1. Stand alone D/A converter DAI-3: The DAI-3 unit corresponds to the interface option D/A-LE of the LE 150/200 amplifier system. It shows both serial and parallel (CENTRONIX) data input for handling up to 3 channels independently. The analog output is 0 V thru +10 V and can be plugged directly to the analog amplifiers described in this catalog. It is obvious, that the DAI-3 unit can be used to control any other system, requiring an analog input control signal. Interfaces: serial RS 232 parallel (CENTRONIX) Resolution: 12 Bit Output signal: 0 V thru +10 V (other settings e.g. bipolar: on request) High modulation rate of output: up to khz with parallel data transfer e.g. for fast feedback control systems. Line operation 3 analog independent outputs front rear 2. PC-plug in cards with analog HV-output The PC plug in-cards generate the analog HV-signal for immediate operation of piezoactuators or other loads. The advantages of the PC-AHV cards are the spacesaving arrangement within the computer cabinet, where no external additional amplifiers are needed and the speed and reliability of data handling. The cards show current boosters for elevated driving dynamics. They are available in single and triple channel versions. General data PCI-Bus 8 bit data bus Setting of port address by a DIL switch Voltage resolution 14 bit for unipolar output 13 bit for bipolar output Width 1 slot PC board dimensions 26 Amplifiers, D/A Converters, Electronic HV-Switches for Piezoactuators

27 PC-AHV +150/1 single channel Output voltage: 0 V thru +150 V Max. peak current: 75 ma Max. average current: 25 ma Resolution: 14 bit Noise: approx. 50 mv Output connector: LEMOSA (BNC adaptors available) PC-AHV 150bp/3 triple channel Bipolar output voltage: 150 V thru +150 V Max. peak current: 50 ma/channel Max. average current: 15 ma (total for 3 channels) Resolution: 13 bit Noise: approx. 50 mv Output connector: LEMOSA (BNC adaptors available) PC-AHV +150/3 triple channel Output voltage: 0 V thru +150 V Max. peak current: 75 ma/channel Max. average current: 25 ma (total for 3 channels) Resolution: 14 bit Noise: 50 mv Output connector: LEMOSA (BNC adaptors available) PC-AHV +500/1 single channel Output voltage: 0 V thru +500 V Max. peak current: 15 ma Max. average current: 5 ma Resolution: l4 bit Noise: approx. 50 mv Output connector: LEMOSA 0S.250 (BNC adaptors available) PC-AHV 150bp/1 single channel Bipolar output voltage: 150 V thru +150 V Max. peak current: 50 ma/channel Max. average current: 15 ma Resolution: 13 bit Noise: approx. 50 mv Output connector: LEMOSA (BNC adaptors available) PC-AHV +500/3 triple channel Output voltage: 0 V thru +500 V Max. peak current: 15 ma/channel Max. average current: 5 ma (total for 3 channels) Resolution: 14 bit Noise: approx. 50 mv Output connector: LEMOSA 0S.250 (BNC adaptors available) Optionen: geänderte Leistungsdaten, Ausgangsbuchsen etc. auf Anfrage Feedback Control Stabilization PiStab-2 Modern HiTechnologies often use physical effects, which are extremely sensitive in magnitude to any small deviation from the correct position of the mechanical components of the device. Any misalignment e.g. by thermal drifts can diminish the device performance e.g. the optical output power of a discretely setup laser resonator). Other examples are the coupling efficiency of freely coupled optical fibers, interferometers, sensor/transducer arrangements in microsystems, biological systems etc. To ensure a stable optimum operation the task is to detect the onset of mechanical misalignment and to readjust the components actively. For micro- and nanopositioning purposes, the first choice include all kinds of piezoactuated systems such as stacks, bimorphs, hybrid systems etc. The stabilization electronics PiStab-2 controls up to 2 degrees of freedom for mechanical longterm stabilization of position sensitive effects. For more details please ask for brochure PiStab-2. Example: Stabilization of a laser resonator piezoelectric actuators x, y controlled end mirrow photodiode signal with modulation PiStab-2 operating + modulation input Mirror mount with 2 piezocontrolled degrees of freedom and a PiStab-2 feedback controlled electronics/supply Arrangement for stabilizing an Ar laser for maximum output power against misalignment by tilting one of the resonator mirrors for 2 degrees of freedom by 2 low voltage actuators in a mirror mount Amplifiers, D/A Converters, Electronic HV-Switches for Piezoactuators 27

28 Accessories: PIEZOMECHANIK supplies a wide range of connecting systems, adaptors, extension cable to make the installation and compatibility of components as easy as possible. When a complete actuator/amplifier system is ordered, the actuators will be equipped with the plugs corresponding the amplifier s connector. Further adaptors are available for the combination different of connector systems. Adaptors: Plug BNC BNC LEMOSA LEMOSA 0S.250 coupler LEMOSA (low voltage systems) LEMOSA 0S.250 (high voltage systems) BNC BNC Coaxial cable RG 178 with plug one end free, length 1.5 m standard, other lengths on request LEMOSA plug LEMOSA plug 0S.250 BNC Extension cables with plug and coupling end, length standard 2 m, other lengths on request LEMOSA system LEMOSA 0S.250 system Extension cables combining different connector systems e.g. BNC-LEMOSA on request. Custom designed amplifiers If you cannot find the proper electronic supply to solve your actuating problem, please contact us. PIEZOMECHANIK can adapt the available standard devices to your needs (e.g. for 12 V, 24 V or other line voltages). On request custom designed electronics can be used. Piezomechanik Dr. Lutz Pickelmann GmbH Berg-am-Laim-Str. 64 D München Tel. XX 49/ 89 / Fax XX 49/89/ info@piezomechanik.com Stand: November 1998