DPC-100LC. Proportional Valve Driver. Features. Applications

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1 DPC-100LC Features +Power True Current-Regulated Flow Control Auto-Configures for 12- or 24-Volt Systems Adjustable Minimum/Maximum Current: 12 V: User-selectable A or A 24 V: User-selectable A or A User-Configurable Dither: Frequency: 20, 33, 83, 125, 167, 200 Hz Amplitude: 0 ±15 % Continual Tracking of Solenoid Inductance & Resistance Short-circuit & Reverse-Polarity Protected Small Form Factor (6 cm x 4 cm board size); also available potted in flanged plastic housing Main (Vdrive) Adjust Inc. Valve PWM Generator Dec. Min. Current Control Max. Ground Dith. Applications Digital to Proportional Conversions Vacuum Trucks Pneumatic Actuators Farm Implements Process Controls The DPC-100LC is a low-cost driver for current-controlled proportional hydraulic/pneumatic valves. Non-pilot-operated, cartridge-style, proportional valves are a cost-effective retrofit to digital (on/off) controls, and the DPC-100LC accepts two simple on/off command inputs to increase or decrease fluid flow. A third input can be optionally used to enable or disable fluid-flow adjustments, allowing the increase/decrease signals to be piggy-backed onto existing remote-control output signals. Unlike many existing driver and amplifier cards which require tuning of P.I.D. parameters to match the valve-solenoid s inductance and time-constant, the DPC-100LC utilises automatic estimation and tracking algorithms to adapt itself to your application. The adaptation is done seamlessly, without having to enter a set-up mode and without any instability or oscillations in the valve command. Aarcomm Systems Inc Fawcett Rd., Coquitlam, B.C., V3K 6V2, Canada Telephone: +1 (604) info@aarcomm.com Page 1 Rev. 3

2 Signal (Wire) Descriptions Signal Wire Colour Description Ground Black Negative ground of the vehicle or system. +Power Orange +12 or +24 VDC for logic. This power source should be live whenever the main control system of the machine is active. This power source only supplies the internal logic; it does not power the valve. Main (Vdrive) Red +12 or +24 VDC for valve-solenoid driver. This power source may be switched on and off independently of +Power, e.g. by a main contactor relay such as in a remote-control system. Valve Yellow Output to valve solenoid. This signal is pulse-width modulated (PWM) at a high frequency, and can optionally have a super-imposed dither. Inc. Green Increase command input. A transition from logic low to logic high on this signal will increase the output current to the solenoid valve by one step. Holding this input at logic high will cause the output current to repeatedly step up. This input only has effect when Main (Vdrive) is powered and the Adjust input is also at logic high. Dec. White Decrease command input. A transition from logic low to logic high on this signal will decrease the output current to the solenoid valve by one step. Holding this input at logic high will cause the output current to repeatedly step down. This input only has effect when Main (Vdrive) is powered and the Adjust input is also at logic high. Adjust Violet Adjust enable input. The Inc. and Dec. inputs will be ignored unless this input is at logic high. In applications where Inc. and Dec. are piggy-backed onto two existing functions, the Adjust input can be used to prevent inadvertent adjustment of the valve-solenoid current when using the existing functions for their original purpose. If the application does not require that Inc. and Dec. be ignored at certain times, the Adjust input may be permanently tied to either +Power or Main (Vdrive). LED Indicators The DPC-100LC has an LED to show whether each of the Adjust, Inc., Dec. inputs and the Valve output is active. The Status LED tells the present operational mode of the DPC-100LC, as described in the Theory of Operation section (later in this document). Aarcomm Systems Inc Fawcett Rd., Coquitlam, B.C., V3K 6V2, Canada Page 2

3 Configuration & Adjustments An eight-pole DIP switch (SW1) and three trimmer potentiometers (Min., Max. and Dither) are used to configure and adjust the DPC-100LC: SW1 Pole Function Details 1 Step Rate ON = Fast, OFF = Slow This switch selects the rate at which the output current will step up and down when the Inc. and Dec. command inputs are held at logic high. For a change in the position of this switch to take effect, +Power must be removed and then re-applied. 2 Number of Steps 3 Reset upon Main off ON = 20, OFF = 10 This switch selects the number of steps between the minimum and maximum valve-solenoid current. For a change in the position of this switch to take effect, +Power must be removed and then re-applied. ON = Reset to minimum valve-solenoid current upon Main (Vdrive) off OFF = Remember valve-solenoid current upon Main (Vdrive) off This switch controls whether the present valve-solenoid current is retained and restored the next time Main (Vdrive) is turned back on. For a change in the position of this switch to take effect, +Power must be removed and then re-applied. 4 High Current ON = 0.75 A (12V) / 0.38 A (24 V) OFF = 0.50 A (12V) / 0.25 A (24 V) This switch, when activated, multiplies the output current by 1.5 times for driving larger valves. A change in the position of this switch takes effect immediately. 5 Zero Step ON = The output current to the valve-solenoid can be reduced to zero OFF = The output current does not go below the minimum current This switch adds an extra zero-current step below the lowest-current step. It is useful in applications where it is desired to have a proportional range from a non-zero flow rate to a given maximum flow rate, yet still be able to command zero flow. Aarcomm Systems Inc Fawcett Rd., Coquitlam, B.C., V3K 6V2, Canada Page 3

4 SW1 Pole Function Details 6,7,8 Dither Frequency OFF,OFF,OFF = 20 Hz OFF,OFF,ON = 33 Hz OFF,ON,OFF = 50 Hz OFF,ON,ON = 83 Hz ON,OFF,OFF = 125 Hz ON,OFF,ON = 167 Hz ON,ON,OFF = 200 Hz ON,ON,ON = Reserved These switches select the dither frequency that is super-imposed on the valve-solenoid drive current. For change in the positions of these switch to take effect, +Power must be removed and then re-applied. Trimmer Function Details Min. Max. Dither Minimum Current Maximum Current Dither Amplitude SW1-4 OFF: A (12 V operation) / A (24 V operation) SW1-4 ON: A (12 V operation) / A (24 V operation) Clockwise = Increasing Current This control determines the minimum valve-solenoid current. A change in the position of this control is immediately reflected at the output. SW1-4 OFF: A (12 V operation) / A (24 V operation) SW1-4 ON: A (12 V operation) / A (24 V operation) Clockwise = Increasing Current This control determines the maximum valve-solenoid current. A change in the position of this control is immediately reflected at the output. 0 ±15% Clockwise = Increasing Dither Amplitude This control determines the amount of dither superimposed on the valvesolenoid current. The dither is a square wave that is up to 15% above and 15% below the average current. To ensure predictability, the dither amplitude set by this control is a fixed percentage of the high-frequency PWM duty cycle rather than being scaled by the solenoid resistance or Min. and Max. adjustments. Aarcomm Systems Inc Fawcett Rd., Coquitlam, B.C., V3K 6V2, Canada Page 4

5 Electrical Characteristics Parameter MIN TYP MAX UNIT Recommended Operating Conditions Supply Voltage, +Power 5 12 or VDC Supply Current, +Power 10 ma Supply Voltage, Main (Vdrive), 12 V operation VDC Supply Voltage, Main (Vdrive), 24 V operation VDC Output Current, 12 V operation A Output Current, 24 V operation A Overcurrent shutdown threshold 1.5 A Operating Temperature (1) C Valve-Solenoid Inductance mh Valve-Solenoid Resistance, 12 V operation Ohms Valve-Solenoid Resistance, 24 V operation Ohms Command Inputs (Adjust, Inc., Dec.) Logic High 6 30 VDC Logic Low 0 4 VDC Input Current Draw, Input Voltage >= 6 V 6 8 (2) 10 ma Absolute Maximum Ratings Storage Temperature Range -40 (3) +125 C +Power Voltage with respect to Ground VDC Main (Vdrive) Voltage with respect to Ground -40 (4) +30 VDC Voltage from any wire w.r.t. Ground, +Power >= 1 V VDC Voltage from any wire w.r.t. Ground, +Power < 1 V VDC Output Short-Circuit Duration Indefinite auto-shutdown (1) +125 C option available please contact Aarcomm for details. (2) When driving the Command Inputs from certain solid-state drivers that have open-load detection, an external pulldown resistor may be required to increase the load current. (3) -55 C storage option available please contact Aarcomm for details. (4) Main (Vdrive) is permitted to be negative provided +Power is less than 1 V. Aarcomm Systems Inc Fawcett Rd., Coquitlam, B.C., V3K 6V2, Canada Page 5

6 Mechanical Characteristics 59.3 mm 39.6 mm Ø3.17 mm, 2 places DPC-100LC-BD (Front View) (Wires come out from back) (Overall thickness 15 mm) 3.17 mm 3.17 mm Board Assembly 3.0 mm Wires exit via grommet on this side mm Ø4.5 mm, countersunk, 4 plcs mm DPC-100LC-PE (Front View) (Overall thickness 26.0 mm) 38.0 mm Ordering Information 98.2 mm Optional Plastic Enclosure Order Code DPC-100LC-BD DPC-100LC-PE Description Low-Current, board assembly c/w 60 cm wires Low-Current, in IP51 plastic enclosure c/w 60 cm wires Aarcomm Systems Inc Fawcett Rd., Coquitlam, B.C., V3K 6V2, Canada Page 6

7 Typical Applications +12 or +24VDC On/Off +Power Main (Vdrive) Adjust Speed Up/Down Inc. Dec. DPC-100LC Valve Ground Controlling Speed of Conveyor Belt +12 or +24VDC Radio Transmitter On/Off Power Main Contactor Output +Power Main (Vdrive) Radio Receiver Adjust Existing Function 1 Existing Function 2 Spare Function Inc. Dec. DPC-100LC Valve Ground Relay Ground Proportional Retrofit to On/Off Remote-Control Aarcomm Systems Inc Fawcett Rd., Coquitlam, B.C., V3K 6V2, Canada Page 7

8 Theory of Operation The DPC-100LC is designed to work with valve-solenoids that have a wide range of inductances and resistances. Load voltage and current are measured 2000 times per second by a combination of dedicated hardware and microcontroller firmware, and sophisticated mathematical algorithms track the dynamically-changing parameters of the solenoid to assure a stable and consistent output current. When the DPC-100LC detects that Main (Vdrive) has been switched on and has stablised, it will automatically configure itself for either a 12 V or 24 V system. Then, when output current is commanded, the solenoid parameters are measured almost instantenously. From this point onward, the solenoid parameters are continually tracked as they change, and used to generate a stable current that does not vary with temperature or system voltage. The Status LED shows thedpc-100lc s operating mode at all times, as follows: Behaviour Mode Details Flashing slowly, half second on, half second off Constantly Illuminated Waiting for Main (Vdrive) and/or command Driving Solenoid The DPC-100LC is waiting for both a stable voltage supply on Main (Vdrive) and for a non-zero current command. When both conditions are met, the DPC-100LC will begin driving the valve-solenoid. A non-zero current command may be present immediately (e.g. the Min. trimmer is set above zero and there is no Zero Step) or upon the first activation of the Inc. input. The DPC-100LC will never drive the solenoid without a command to do so. The valve-solenoid is being actively driven and its parameters are being tracked; current control is working optimally. Aarcomm Systems Inc Fawcett Rd., Coquitlam, B.C., V3K 6V2, Canada Page 8

9 Behaviour Mode Details Flashing quickly, 5 times per second Briefly illuminates once per second Incompatible Solenoid Detected Short-Circuit Detected in Solenoid If a solenoid with resistance or inductance outside the range supported by the DPC-100LC is detected from the outset, the solenoid will not be driven and this error condition will persist until Main (Vdrive) is turned off. Common causes for this error to occur from the outset are: Solenoid resistance too large or too small; Solenoid inductance too large or too small. Please refer to the Electrical Characteristics section (earlier in this document) for acceptable solenoid resistance and inductance ranges. However, if the DPC-100LC is already driving the solenoid, it will do its best to continue to do so despite this error, although performance may be nonoptimal. Typical causes for this error to be detected during solenoid-driving are: Maximum and/or commanded current too large for solenoid; Main (Vdrive) supply voltage too low; Dither amplitude too small or too large; Excessively unstable (noisy) Main (Vdrive) supply. This error occurs during solenoid-driving when the instantaneous current exceeds about 1.5 amps. The DPC-100LC will try continually, once per second, to recover from this condition; each time, the smallest amount of energy possible is driven into the Valve output so as not to cause damage to the wiring or the DPC-100LC itself. Some causes of this error include: Wiring harness chafing or other damage; Solenoid windings internally short-circuited; Water (or other conductive liquid) contamination in wiring or solenoid. Set-up Procedure With the DPC-100LC unpowered, the DIP switches should first be set for the current-stepping behaviour, current range, response to Main (Vdrive) on/off, and dither frequency desired. Then, set all three Min., Max. and Dither trimmers to approximately their 9 o clock positions. Switch on +Power and Main (Vdrive). Then, if Zero Step is enabled, momentarily activate the Inc. input while holding the Adjust input on. Adjust the Min. potentiometer for the desired minimum solenoid current. Next, activate and hold the Inc. and Adjust inputs until the current stops increasing. Adjust the Max. potentiometer for the desired maximum solenoid current. Note: If the solenoid current stops increasing while rotating the Max. trimmer clockwise, and the current is still not at the desired Aarcomm Systems Inc Fawcett Rd., Coquitlam, B.C., V3K 6V2, Canada Page 9

10 maximum level, then either the solenoid s resistance is too high to support the current or the Main (Vdrive) voltage is too low. Finally, adjust the Dither trimmer for the desired amount of dither. We recommend at least a small amount of dither be used in every application, as dither assures consistent valve positioning and also assists with dynamic solenoid parameter tracking. Aarcomm Systems Inc Fawcett Rd., Coquitlam, B.C., V3K 6V2, Canada Page 10