Precision Variable Frequency Drive for AC Synchronous Motor

Transcription

1 Precision Variable Frequency Drive for AC Synchronous Motor Final Report May Client Jim Walker Faculty Advisor Dr. Ajjarapu Group Members Matt Shriver Nick Nation Jason Kilzer Dave Reinhardt DISCLAIMER: This document was developed as a part of the requirements of an electrical and computer engineering course at Iowa State University, Ames, Iowa. This document does not constitute a professional engineering design or a professional land surveying document. Although the information is intended to be accurate, the associated students, faculty, and Iowa State University make no claims, promises, or guarantees about the accuracy, completeness, quality, or adequacy of the information. The user of this document shall ensure that any such use does not violate any laws with regard to professional licensing and certification requirements. This use includes any work resulting from this student-prepared document that is required to be under the responsible charge of a licensed engineer or surveyor. This document is copyrighted by the students who produced this document and the associated faculty advisors. No part may be reproduced without the written permission of the senior design course coordinator. March 29, 2007

2 Table of Contents List of Figures... iv List of Tables... v List of Definitions... vi 1.0 Introductory Material Executive Summary Acknowledgments Problem Statement Operating Environment Intended User and Uses Assumptions and Limitations Assumptions Limitations Expected End Product and Other Deliverables Project Approach and Results End Product Functional Requirements Resultant Design Constraints Approaches Considered and One Used Detailed Design Overview of Final Design Components of Precision VFD Power Source Pulse Width Modulation Circuits Sine Wave Generator Circuit Triangle Wave Generator Circuit Comparator Circuit Inverter Circuit Simulation Results for the Pulse Width Modulator IGBT Bridge Low Pass Filter Transformer Frequency Counter Strobe Light System Implementation Process Description End-Product Testing Description Testing of Waveform Generators Testing of Comparator and Inverter Circuits Testing of the IGBT Bridge and Low Pass Filter Testing of the Transformer Testing the Pulse Width Modulator with the Frequency Counter Testing of the Strobe Light Project End Results ii

3 3.0 Resources and Schedules Resource Requirements Personnel Requirements Other Resource Requirements Financial Requirements Schedules Detailed Gantt Chart Deadlines Gantt Chart Project Evaluation Commercialization Recommendations for Additional Work Lessons Learned Risk and Risk Management Project Team Information Closing Summary References Appendix A Parts List Appendix B Circuit Schematics Appendix C Testing Forms Appendix D Exar XR-2206 Datasheet Appendix E Strobe Disc iii

4 List of Figures Figure 1: Overall Block Diagram... 6 Figure 2: Precision Variable Frequency Drive... 7 Figure 3: Astrodyne Power Supply PT-45C (7)... 7 Figure 4: Block Diagram of Gate Signal Generation for PWM... 8 Figure 5: Sine Wave Generator Schematic... 9 Figure 6: Triangle Wave Generator Circuit Figure 7: Triangle Wave Amplifier Schematic Figure 8: Comparator Schematic Figure 9: Inverter Schematic Figure 10: PSpice Simulation Schematic of Pulse Width Modulator Figure 11: Triangle Waveforms Before & After Amplifier Circuit Figure 12: Input and Output Waveforms of the Comparator Figure 13: Input and Output Waveforms of the Inverter Figure 14: IGBT Bridge Figure 15: IGBT Bridge Output Waveform Figure 16: Complete Schematic of IGBT Bridge and Low Pass Filter Figure 17: IGBT & Low Pass Filter Output Waveforms Figure 18: Photo of Frequency Counter Figure 19: Strobe Light Schematic (8) Figure 20: Complete Schematic of Gate Signal Generating Circuits Figure 21: IGBT Bridge, Low Pass Filter, and Transformer Schematic Figure 22: Picture of Sine Waveform Figure 23: Picture of Triangle Waveform Figure 24: Combined Detailed Gantt Chart Figure 25: Deadlines Gantt Chart iv

5 List of Tables Table 1: Sine Wave Generator Parts Table 2: Triangle Wave Generator and Amplifier Parts Table 3: IBGT Bridge Parts Table 4: Low Pass Filter Parts Table 5: Strobe Light Parts List Table 6: Original Personal Effort Table 7: Revised Personal Effort Table 8: Actual Personal Effort Table 9: Original Other Resources Table 10: Revised Other Resources Table 11: Final Other Resources Table 12: Original Financial Requirements Table 13: Revised Financial Requirements Table 14: Final Financial Requirements Table 15: Project Evaluation Table 16: Summation of Parts for PVFD Table 17: Anticipated Risks and Action Plan Table 18: Unanticipated Risks and Resultant Management Table 19: Complete Parts List v

6 List of Definitions AC: Alternating Current. - an electric current that reverses direction at regular intervals, having a magnitude that varies continuously in sinusoidal manner. (1) DC: Direct Current - an electric current of constant direction, having a magnitude that does not vary or varies only slightly. (2) LCD: Liquid Crystal Display - is a thin, flat display device made up of any number of color or monochrome pixels arrayed in front of a light source or reflector. (3) VFD: Variable Frequency Drive - is a system for controlling the rotational speed of an alternating current electric motor by controlling the frequency of the electrical power supplied to the motor. (4) IC: Integrated Circuit - a circuit of transistors, resistors, and capacitors constructed on a single semiconductor wafer or chip, in which the components are interconnected to perform a given function. (5) IGBT: Insulated Gate Bipolar Transistor - combines the simple gate drive characteristics of the MOSFET with the high current and low saturation voltage capability of bipolar transistors by combining an isolated gate FET for the control input, and a bipolar power transistor as a switch, in a single device. (6) vi

7 1.0 Introductory Material In the following sections the Precision Variable Frequency Drive (PVFD) design project is defined. The intended uses and users are defined along with the end product description. 1.1 Executive Summary Synchronous motors are motors that run at a specific speed. A customer may want to run the motor at different speeds, like for a record player that needs to operate at 45 and 33 1/3 rpm. These motors have a tendency to vary from the specified speed due to losses in the motor among other things. This product will be designed to adjust the frequency between 58 to 62 hertz. After plugging the precision variable frequency drive into a standard wall, a synchronous motor can be plugged into the precision variable frequency drive with a standard three pronged plug. The frequency can then be changed by the turn of a dial. An LCD display will display the frequency that the motor is operating. The digital display will be accurate to one tenth of a hertz. In addition, a strobe light will allow the user to observe the rpm of the motor. The precision variable frequency drive will have a long term drift that requires a gradual decrease/increase of speed that allows for more accurate tuning. Currently, the group has developed a working simulation of the entire project. The variable waveforms have also been developed. The IGBT bridge and inverter and comparator circuits are also working properly. This semester, the group is developing a prototype of the precision variable frequency drive. A simulation of the entire project has been developed and is working properly. All separate parts of the project have been developed and tested except the power supply and transformer. These separate circuits have been tested alone and have not been tested all together. The group is currently putting all of the circuits together to produce a variable frequency drive. Variable frequency waveforms have been developed along with the inverter and comparator circuits. The IGBT pulses have also been developed. For the rest of the semester, the group is going to finish the prototype for the precision variable frequency drive. Currently, power supply issues and stepping up the voltage after the IGBTs are the main focus of the group. A box to contain the PVFD and the strobe light system will also need to be constructed. 1.2 Acknowledgments Jim Walker deserves thanks for his assistance to us in this project. His equipment, technical advice, and financial aid were essential for the success of this project. Prof. Ajjarapu s technical support throughout this project helped ensure the success of the project and better understanding for the group. Graduate student Ryan Konopinski also provided valuable advice and help dealing with the project. 1

8 1.3 Problem Statement The general problem is the speed control of a synchronous motor. The synchronous motor and the subsequent drive mechanism do not always keep the correct speed. One example of a synchronous motor not running at the correct speed is with a record player. If the motor is not running at the correct speed, the record sounds out of pitch. The general solution to the above mentioned problem is creating a precision variable frequency drive, which will allow the user to manually change the frequency using a dial. The PVFD will allow the user to change the speed of the motor and what the motor is driving until the correct speed is attained. 1.4 Operating Environment The operating environment for the precision variable frequency drive is indoors. Therefore, it will not be subject to outdoor weather or extreme temperatures. Extreme dust will also not be an issue because the device will be covered. 1.5 Intended User and Uses The intended users of the PVFD are anyone needing to change the speed of a synchronous motor. The main use of the PVFD is with a record turn-table, so the main user will be avid music listeners. Recreational music listeners would not notice a small change in pitch caused by the turn-table not turning at the correct speed. The user will also be considered a lay person without extensive technical knowledge. The intended use is to change the frequency of any synchronous motor. The PVFD was designed with the idea of controlling the speed of a record players turntable. The PVFD can also be used with any small power synchronous motor. 1.6 Assumptions and Limitations The following is a list of assumptions and limitations that were developed for the PVFD project Assumptions This is the list of the assumptions needed to complete this project. Constant linkage In many record players the turntable is driven by a belt connected to the motor. Over time this belt will stretch and change the speed of the turntable. Basically, an increase in motor speed by a certain factor will result in an increase in the speed of the turntable by the same factor. Plug the power cord from the record player can plug into a standard three pronged outlet. 2

9 1.6.2 Limitations These are the design constraints that will define the precision variable frequency drive project. Precision the precision variable frequency drive will be accurate to Hertz. Price the total end product cost must be less than $1,000. Frequency Range 58 to 62 Hertz with step of Hertz. Voltage Range 110 to 135 Volts. Stability the precision variable frequency drive must be stable. Short term stability of less that +/- 0.01%. It shall not be affected by minor fluctuations in incoming voltage (80-130V) or frequency (50-70Hz). Power Output 75 W minimum. Input Voltage the input voltage will be a standard household outlet of around 110 VAC at 60 Hz single phase 1.7 Expected End Product and Other Deliverables The end product is the precision variable frequency drive, which is contained in a small box. Along with the PVFD, a strobe light system prototype is included. This strobe light system can be used to check the RPM of the turntable connected to the variable frequency drive. Circuit diagrams, parts lists, a user s manual for both the PVFD and the strobe light system, and a quick user s guide will also be included. The quick user s guide is a one page diagram of how to use the variable frequency drive. 3

10 2.0 Project Approach and Results This section describes the design constraints and the different technologies that were considered for the project and why they were or were not chosen. The technologies that were chosen have been fully outlined in this section as well as how they were tested for functionality. 2.1 End Product Functional Requirements Below is a list of the functional requirements of the PVFD: 1. Minimum output of 75 W 2. Continuously selectable frequency from 58 to 62 Hz with long term (drift) and short term stability of less then +/-0.01% 3. Digital LCD read-out of frequency accurate to three decimal places 4. Portable strobe system for measuring a turntables RPM 5. Safety The PVFD is required to output at least 75 Watts in order to power the motor and the accompanying drive mechanism. The continuously selectable frequency will allow the user to adjust the frequency that is fed into the motor. After long term use not all motors operate at the desired frequency causing performance issues. The PVFD allows the user to change the frequency of the motor until the desired frequency is reached. The motor frequency controller needs to be accurate with longterm (drift) and short-term stability of less than +/-0.01% to ensure proper functionality. The digital LCD read-out is used so the user can accurately determine what frequency the PVFD is operating at, and can easily set the frequency for a specific motor again at a later date. A portable strobe system was included with the PVFD for use with turntables. The strobe system measures the RPM rate of the turntable at either 33 1/3 RPM or 45 RPM. Safety of the device was also a requirement. By encasing the device inside a wooden box and warning the user of the potential for electrical shock if handled while energized the risk of injury was minimized. 2.2 Resultant Design Constraints From the assumptions, limitations, and functional requirements made on the PVFD the following resultant design constraints were derived: 1. Minimum of 75 Watt output 2. Adjustable frequency from 58 to 62 Hz with long term and short term stability accurate to 0.01% 3. Frequency display showing three decimal points 4

11 4. Plug compatible with a standard three pronged household outlet 5. Constant motor linkage 6. Safety 7. Price The PVFD must output at least 75 Watts in order to power the motor it is attached to and move the drive mechanism. The PVFD must have an adjustable frequency between 58 and 62 Hz with long and short term stability accurate to Hz. The design requirements also called for a frequency display showing three decimal places in order to measure the output frequency. It was assumed that the PVFD would be used might the house for various items with synchronous motors so it was assumed that it would be plugged into a standard three prong 110 Volt, 60 Hz, single phase socket. A charge in speed of the motor must also result in a change the speed of the device it is driving, constant motor linkage is assumed. The safety of the user was taken into account when using the PVFD. By encasing the device in a wooden box the risk of electrical shock and other danger to the user is minimized. One of the goals of the project was to design and construct the PVFD for under $1000, which is the cost of the current product on the commercial market. 2.3 Approaches Considered and One Used Two different technologies were considered when the approach to designing the VFD and how the frequency was to be varied. The first approach was to use a crystal oscillator. A crystal oscillator works by placing a thin slice of quartz crystal in between two electrically conductive plates and applying an AC signal to it. When the circuit is first energized the AC signal is random, however a small portion of it is at the resonant frequency of the crystal. The crystal then begins to oscillate at the resonant frequency and dominate the output. Crystal oscillators can be designed for any frequency, but most are produced around the frequencies of 3.58, 10, , 20, 33.33, and 40 MHz. The advantage to using a crystal oscillator is the high accuracy that it provides, however this approach was abandoned because the crystal oscillators currently on the market operate at too high a frequency for what the project called for. The second technology considered was a pulse width modulation system. This system would give the desired frequency range and accuracy to meet the design requirements. The disadvantage to the pulse width modulation system was the large number of components needed to make it work. This increased the chance that a component would fail to work properly and cause the whole system to fail. Despite this disadvantage of the PWM system it was selected for 5

12 the VFD, because to could operate in the needed frequency range and the components were readily available. Figure 1 below shows the PWM system designed for the VFD. The first part would consist of a triangle and a variable sine wave. The frequency of the sine wave is varied because it determines the frequency of the output signal. These two waves are passed on to a comparator. By comparing the two signals pulses are created. The output of the comparator is sent to an inverter where the pulses are inverted. These two pulses are the control signals for the IGBT bridge. These control signals are sent on to the IGBT bride which creates pulses. By passing the pulses through a low pass filter a sine wave is created. The filter also removes any unwanted harmonics in the signal. This wave would then pass through a transformer to step the voltage up to the 120 V needed to operate the motor. Finally a frequency counter would be placed at the output to measure the frequency from the device. With these components working properly the design constraints would be met. 2.4 Detailed Design Figure 1: Overall Block Diagram Overall pictures of the end product as well as some schematics of the components and parts lists and cost of parts of the variable frequency drive will be shown in the next few sections. Also the changes from the original design will be discussed Overview of Final Design Figure 2 shows the PVFD. The device plugs into an ordinary three pronged wall outlet. The frequency of the output voltage can be varied by turning the knob that is located below the frequency display. The frequency of the power outputted is displayed on the frequency display with precision of 0.01 Hz. The outlet on the left side of the picture is where the synchronous motor will be plugged in. The weight of the box is 5 pounds and the box is 10 inches long, 8 inches across and 6 inches deep. 6

13 Figure 2: Precision Variable Frequency Drive All the components inside this box are detailed and explained in the following sections Components of Precision VFD The PVFD has several key components. A brief description of the each of the components along with some technical explanation is included in the following sections Power Source The PVFD contains a power supply which takes the 110 VAC from the wall and changes it into lower DC voltages. These different voltages are used to power the IC s used on the circuit board. The power supply has DC voltage outputs of +/-15V and +5V. Figure 3 shows a picture of the power supply. Figure 3: Astrodyne Power Supply PT-45C (7) This power supply was purchased for $42. 7

14 Pulse Width Modulation Circuits The brain of the precision PVFD is the pulse width modulator. PWM is used to change the frequency of the output voltage and the following sections describe how this is done. The PWM provides control of the frequency down to.01 Hz. Figure 4 shows the waveforms that are needed to compare against each other to produce the square pulses needed to operate the IBGT bridge (the IGBT bridge is discussed in section ). Figure 4: Block Diagram of Gate Signal Generation for PWM 8

15 Sine Wave Generator Circuit The precision of the sine wave generator circuit is very important because the frequency that is generated is the same frequency that will be outputted to the synchronous motor. This circuit then must only produce a sine wave with a frequency between 58 and 62 Hz. Exar manufactures the XR-2206, which is an IC that produces a sine wave. Pleas refer to Appendix D for the datasheet of the XR Figure 5 shows the schematic of the sine wave generator circuit. Figure 5: Sine Wave Generator Schematic The frequency changing is done by the 2kΩ potentiometer. It was determined that to achieve this range of frequency, a resistance from 15470Ω to 16715Ω on pin 7 on the XR-2206 chip. A 2kΩ potentiometer was purchased to cover this range in resistance. Then in order to reduce the variance of the 2kΩ down to the desired 1245Ω the following calculation was done. R1 R2 2kΩ 3.3kΩ RRANGE = = = 1245Ω R1 + R2 2kΩ + 3.3kΩ R = R = 1245Ω MAX RANGE R1 R2 0kΩ 3.3kΩ RMIN = = = 0Ω R1 + R2 0kΩ + 3.3kΩ The above calculations explain why a 3.3kΩ resistor is in parallel with the 2kΩ potentiometer. The 10kΩ potentiometer was used in tuning the amplitude and will remain constant during the normal mode of operation. 9

16 Table 1 shows a total list of parts for the sine wave generator circuit and there associated prices. Table 1: Sine Wave Generator Parts Part Device Price XR-2206 Monolithic Function Generator (Exar) $ kΩ Resistor $ Ω Resistor $ kΩ Resistor $ Ω Resistor $ kΩ Resistor $ kΩ Resistor $ kΩ Potentiometer $0.58 2kΩ Potentiometer $0.58 1uF Capacitor $ uF Capacitor $0.09 Total $ Triangle Wave Generator Circuit The triangle wave generator circuit uses the same chip that the sine wave generator circuit uses (XR-2206). The only differences are the values of resistance and also in the triangle circuit the resistor between terminals 13 & 14 has been removed. The Exar XR-2206 IC is design to produce a triangle wave when there is no connection between pins 13 & 14. Figure 6 shows the schematic of the triangle waveform generator circuit. Figure 6: Triangle Wave Generator Circuit 10

17 Please note that on both the sine and triangle waveform generator circuits the output comes from pin #2 of the XR-2206 chip. The two potentiometers were used to set the frequency of the triangle wave to 2.5 khz. The output of the triangle wave needs to be 2-3 times the amplitude of the sine wave; therefore the following amplifier was designed to increase the amplitude of the triangle wave. Figure 7 shows an op amp used to amplify the triangle waveform. Figure 7: Triangle Wave Amplifier Schematic The resistors in the amplifier circuit above were determined by the following equation: RFEEDBACK 3.3kΩ GAIN = = = 2.2 RINPUT 1.5kΩ Table 2 shows a total list of parts for the triangle wave generator circuit and the amplifier and there associated prices. Table 2: Triangle Wave Generator and Amplifier Parts Part Device Price XR-2206 Monolithic Function Generator $ Ω Resistor $ kΩ Resistor $ kΩ Resistor $ kΩ Resistor $ kΩ Resistor $ kΩ Potentiometer $ kΩ Potentiometer $0.58 1uF Capacitor $ uF Capacitor $0.09 ua741 Operational Amplifier $0.15 Total $

18 Comparator Circuit Both the amplified triangle wave and the sine wave serve as inputs to a comparator circuit that compares the two signals. Figure 8 shows the schematic for the comparator circuit. Figure 8: Comparator Schematic The comparator circuit is important because this is where the control (gate) signals for the IGBT bridge are created. The ua741 op amp can be purchased for $ Inverter Circuit The IGBT bridge requires two gate signals. One is provided by the comparator and that signal controls two of the four IGBTs. The inverse of that same signal needs to be feed to the other IGBTs. An inverter circuit was designed to invert the signal that was created by the comparator. Figure 9 shows the schematic of the inverter circuit. Figure 9: Inverter Schematic This circuit simply inverts the comparator output. With this signal there are now two signals ready to be sent to the IGBT bridge. The ua741 op amp can be purchased for $

19 Simulation Results for the Pulse Width Modulator In order to assure that the design that was developed would work a simulation was created of all the parts of the pulse width modulator. PSpice software was used to simulate the pulse width modulation circuits. PSpice does not have the XR-2206 chip in its library but it does have sources that can be used to create the same waveforms that the XR-2206 chips produce. Figure 10 shows the PSpice simulation schematic that was created. The circuits in the above sections are simulated in the following simulation. Triangle +Vcc -Vcc Amplifier 5Vdc R2 V3 V4-5Vdc 3.3k +Vcc 0 0 U OS2 V1 =.1 V2 = -.1 TD = 1p TR = u TF = u PW = 1p PER =.5m V1 0 Triangle Wave R1 1.5k 2 ua741-7 V+ V- 4 -Vcc OUT OS VOFF = 0 VAMPL =.1 FREQ = 60 V2 0 Sine Wave Comparator 3 2 U2 + - ua741 +Vcc 7 V+ V- 4 -Vcc OS2 OUT OS Gate Signal 3 2 V ua741 Inverter U Vcc 7 V+ V- 4 -Vcc OS2 OUT OS Inverted Gate Signal Figure 10: PSpice Simulation Schematic of Pulse Width Modulator The triangle waveform needs to be amplified before it is ready to be compared with the sine wave. Figure 11 shows the waveforms before and after the triangle amplifier circuit. Note the difference in amplitude of the two waveforms. The higher amplitude is the output and the smaller amplitude is the input to the amplifier. V Figure 11: Triangle Waveforms Before & After Amplifier Circuit 13

20 The next step in the circuit is the comparator where the amplified triangle wave is compared to the sine wave. The following figure shows the two inputs and also the gate signal. Figure 12: Input and Output Waveforms of the Comparator The last part of the pulse width modulation circuit is the inverter circuit. The following figure shows the input and the output of the inverter circuit. The reader should notice that the waveforms are the same just inverted. On the following figure the square marker denote the input and the diamond markers denote the output waveform of the inverter. Figure 13: Input and Output Waveforms of the Inverter 14

21 IGBT Bridge This bridge consists of four IGBTs as shown in Figure 14. The power source to the bridge is +15Vdc. The original pulses coming from the comparator control IGBTs Q1 and Q4. This creates the positive pulses seen in Figure 15. The inverted pulses from the inverter control IGBT s Q2 and Q3 and create the negative pulses in Figure 15. Figure 14: IGBT Bridge Figure 15: IGBT Bridge Output Waveform Please note on the above figure above the vertical axis is voltage with the horizontal being time. 15

22 The IGBTs were donated by STMicroelectronics as samples. Table 3 shows a total list of parts for the IGBT bridge and their associated prices. Table 3: IBGT Bridge Parts Low Pass Filter Part Device Price STGW30NC60W IGBT $4.34 STGW30NC60W IGBT $4.34 STGW30NC60W IGBT $4.34 STGW30NC60W IGBT $4.34 Total $17.36 The output of the IGBT is a series of square pulses. When those pulses are fed through a low pass filter a sine wave emerges. This sine wave has the same frequency as the sine wave that was inputted to the comparator. Figure 16 shows the complete schematic of the IGBT with the low pass filter. Figure 16: Complete Schematic of IGBT Bridge and Low Pass Filter The low pass filter was designed to filter out all the harmonics above the cut-off frequency w 0 and leaving all harmonics below. The cut-off frequency was chosen to be 72 Hz. The following equation determined the values for the resistor and capacitor in the low pass filter. 1 1 ω 0 = = = 72.34Hz 2 π R C 2 π 22Ω.0001F Table 4 shows a total list of parts for the low pass filter and there associated prices. Table 4: Low Pass Filter Parts Part Device Price 22Ω Resistor $ uF Capacitor $0.09 Total $

23 Figure 17 shows the output of the IGBT bridge on the top and the same signal after it goes through the low pass filter Transformer Figure 17: IGBT & Low Pass Filter Output Waveforms The transformer has not yet been purchased. The transformer s primary winding will have a voltage rating of 8V and the secondary winding will have a rating of 110V. This section will be updated for the final bound copy Frequency Counter The frequency counter is connected to the circuit after the transformer and measures the frequency of the AC signal being outputted. This device displays the frequency of the voltage it was sampling on a LCD screen. Figure 18 shows a picture of the frequency counter that was purchased. Figure 18: Photo of Frequency Counter This frequency counter was donated by Commonwealth Edison. To purchase this part it would cost $

24 Strobe Light System A strobe light system was built independently of the PVFD. This strobe light was designed by Vinyl Engine. The individual components of the strobe light were purchased and assembled in the manner shown on the schematic in Figure 19 and with the parts in Table 5. The last part of the strobe light system is the special tuning disc. The discs, shown in Appendix E, have a circle of marks on them. Each disc corresponds to a different RPM (33 1/3 or 45). When the strobe light shines on the disc the marks will appeared to not be moving if the turntable RPM is at one of the desired speeds. Figure 19: Strobe Light Schematic (8) Table 5: Strobe Light Parts List Part Device Cost($) CD4060B IC - Binary Ripple Counter $0.50 CD4013B IC - Dual D-flip-flop $1.00 CD4013B IC - Dual D-flip-flop $1.00 BC327 Silicon PNP Transistor $0.10 N/A Diode $0.50 N/A Diode $ MHz Quartz Crystal $ pF Capacitor $ pF Capacitor $ pF Capacitor $ pF Capacitor $ uF Capacitor $0.25 1MΩ Resistor $1.00 1kΩ Resistor $ kΩ Resistor $1.00 Push Button Switch $2.25 9V Alkaline Battery $1.00 Wood Case 16-pin DIP Socket $ pin DIP Socket $1.00 Total $

25 2.5 Implementation Process Description The following is a brief summary of how the variable frequency drive was constructed. Connect the circuit as shown in Figure 19. There is a full sheet schematic of Figure 20 in Appendix B. Figure 20: Complete Schematic of Gate Signal Generating Circuits The output of the comparator serves as the negative input of the inverter and a reference signal is plugged into the positive side of the terminal. The output is the inverse of the original signal being compared. Then the IGBT bridge needs to be assembled. See Figure 21 before completing the following steps. Take two of the IGBTs and place a jumper across the number two leads of the chip. Then take a jumper wire and hook the number three leads together for the two remaining IGBTs. Then take another two jumpers and hook the number three leads of the first pair of IGBTs to the number two leads of the second pair of IGBTs. Figure 21: IGBT Bridge, Low Pass Filter, and Transformer Schematic 19

26 WARNING: Make sure the all power is off while completing the next steps. Attach a wire to the positive voltage terminal of the AC to DC converter and attach it to the set of IGBTs that have there number two leads connected. Then attach the negative terminal of the AC to DC converter and attach it to the two IGBTs that have the number three leads connected. Then to apply control the devices, take two jumpers and twist ends of the wires together and attach it to the comparator output and attach the two separated ends and attach them the number 1 leads of two adjacent IGBTs. Then attach two jumpers to the output of the inverter and the other two ends to the number one pins of the remaining two adjacent IGBTs. When completed the circuit should look like the one in Figure 21. To attach the filter, you will need two jumpers. One jumper will go in between the first two IGBTs and the other end will attach to the end of the 100 ohm resister. The other jumper has to get attach in between the last two IGBTs. Attach the 100uF capacitor in parallel at the end of the two wires, after the resister. The primary coil of the transformer will be located across the capacitor of the low pass filter. Connect one wire from the primary winding (coil) to one side of the capacitor in the low pass filter and the other wire from the transformer (primary coil) and connect it to the other side of the capacitor. The frequency counter and the outlet receptacle need to be attached. Take two more jumpers and attach them to one of the outputs of the transformer (secondary coil). One of the wire ends will go to one of the screws on the frequency counter and the other wire goes to one of the screws of the plug in receptacle. Now attach two more wires to the other output of the transformer and attach one of the ends to the other screw of the outlet receptacle and the other jumper will go to the other screw of the frequency counter. Lastly, mark spots for each of the components on the plastic box chosen to enclose this device. Cut out the areas so the receptacle, frequency counter, and the frequency adjustment knob can fit through the holes and can be securely attached to the box. 2.6 End-Product Testing Description Testing was performed by other members of the design team. The area chosen to test the device was 1212 Coover Hall. The room has oscilloscopes, digital multimeters, and power supplies. Each circuit was tested independently and also integrated Testing of Waveform Generators The waveform generators were hooked up to the power supply and an oscilloscope. Both waveforms were variable. The sine wave was able to be varied from 57.9 Hz to 62.1 Hz. This exceeded the specifications that were defined in the project description. It was able to change by.01 Hz. It is very important that the frequency stays between 55 and 65 Hz to assure the motors 20

27 and transformers are not damaged. A picture of the sine wave graphed on the oscilloscopes is shown in Figure 22. Figure 22: Picture of Sine Waveform Also the triangle wave generator was hooked up to the oscilloscope. The output frequency of the triangle wave is not as critical as the sine wave. The triangle wave was able to be varied from 100 Hz to 10 KHz. An important thing to note is that the higher the frequency of the triangle wave, the smoother the pulses were out of the comparator. The triangle frequency is set at 2.5 khz because that was the maximum frequency the IGBTs can switch at. A picture of the triangle wave is shown in Figure 23. Figure 23: Picture of Triangle Waveform The testing of the wave forms was done by Nick Nation. The test reporting forms are located in Appendix C. 21

28 2.6.2 Testing of Comparator and Inverter Circuits The comparator and inverters were connected to both of the waveform generators. The outputs were displayed on the oscilloscope. The oscilloscope showed two straight lines which is what was supposed to be displayed because the inverted signal is just the opposite. The pulses were not exactly square pulses. This is due to the slight delay of the op amps. However the delay is needed for the end product, otherwise the IGBTs would short out and ruin them. The actual testing report form for the comparator and inverter circuits was done by Jason Kilzer and the testing forms are located in Appendix C Testing of the IGBT Bridge and Low Pass Filter The IGBTs and low pass filter were hooked up to a power supply and the results were displayed on the oscilloscope. The output of the low pass filter was a sine wave with a voltage ripple of about 5%. This ripple was considered minimal, and when PVFD is hooked up to a motor testing shall be done to see if this voltage ripple is too significant Testing of the Transformer The testing of the transformer has not been completed because the transformer is not on site. The transformer will be tested individually before it is placed after the low pass filter. This device is being purchased and thus should not require a great deal of testing Testing the Pulse Width Modulator with the Frequency Counter All the separate circuits of this project have not been tested together. Because the transformer has not been installed the whole circuit can not be tested with the frequency counter. The frequency counter needs to have at least a 20 VAC signal to detect the frequency. The complete circuit will be tested with the frequency counter and the testing forms will be included in the final bound copy of this report Testing of the Strobe Light The testing of the strobe has not been completed because the parts for the strobe are not on site. The strobe light will be tested and its testing form will be included in the final report bounded. 2.7 Project End Results The success of the wave generator was due to the large amount of time it took to research the XR-2206 chip and determine the chips capabilities. This chip performed very accurately for the variable frequency drive. The wave generators, both of them, were considered a success due to the clean wave that each chip generated. 22

29 The comparator and the inverter circuits were simple circuits that were taught in the basic of electrical engineering classes. These circuits are very straight foreword and were a success due to the simplicity in building them. The success of the IGBT rectifier portion of the project was due to the outside help that was given to the group from a masters student. It was his expertise that lead the group in the direction that was taken. From there, individual research and hard work of the team led to building the part and understanding of how and why it works. The strobe light was a failure was because of the groups inexperience of delivery schedules of other companies. The parts were ordered through a company, but because inexperience and busy schedules of the group members, the group became aware too late that the parts were never delivered. A second company is now processing our order and an update of this will be in the final bound copy. 23

30 3.0 Resources and Schedules This section outlines the resources of time and money used to complete the project. It also shows the schedules for the project. 3.1 Resource Requirements This section compares the personnel, other, and financial requirements from the two previous reports and the final one Personnel Requirements The breakup of the personal hours for each task was very important; it allowed each group member to plan ahead for how long each task was expected to take. The following tables give a comparison of how the work for each task was broken up. Table 6: Original Personal Effort Name Task 1 Task 2 Task 3 Task 4 Task 5 Task 6 Task 7 Task 8 Totals Reinhardt, Dave Kilzer, Jason Nation, Nick Shriver, Matt Total(hours) Table 7: Revised Personal Effort Name Task 1 Task 2 Task 3 Task 4 Task 5 Task 6 Task 7 Task 8 Totals Reinhardt, Dave Kilzer, Jason Nation, Nick Shriver, Matt Totals(hours) Table 8: Actual Personal Effort Name Task 1 Task 2 Task 3 Task 4 Task 5 Task 6 Task 7 Task 8 Totals Reinhardt, Dave Kilzer, Jason Nation, Nick Shriver, Matt Totals(hours) The drastic change in the final tasks of the project came for several reasons. Construction and testing of the final device components did not begin right away and that time had to be made up. 24

31 Also, several component parts were late in arriving to the site causing more delays. Trouble shooting the components also proved to be a challenging task for everyone Other Resource Requirements The following tables compare other resources through out the development of the project. Table 9: Original Other Resources Item Team Hours Other Hours Cost Miscellaneous Parts & Materials 0 0 $20.00 Device Components 2 0 $ Project/Poster Printing 5 0 $40.00 Total 7 0 $ Table 10: Revised Other Resources Item Team Hours Other Hours Cost Miscellaneous Parts & Materials 0 0 $20.00 Device Components 2 0 $65.94 Project/Poster Printing 5 0 $0.00 Total 7 0 $85.94 Table 11: Final Other Resources Item Team Hours Other Hours Cost Miscellaneous Parts & Materials 0 0 $20.00 Device Components 2 0 $86.90 Project/Poster Printing 5 0 $0.00 Total 7 0 $86.90 Differences in the revised and original tables can be attributed to the fact that the project poster was printed for free and materials such as glue and poster board were donated. Device components increased in the final table from the revised table because printed circuit boards were purchased for the strobe light and device components to be placed on. The price of material for the box also drove the price up. The decrease from the original table to the final table is due to the fact that we were able to acquire several pieces for free as donations. 25

32 3.1.3 Financial Requirements The following tables are the financial requirements of the project. Table 12: Original Financial Requirements Item W/O Labor With Labor Parts & Materials Device Components $ $ Project/Poster Printing $40.00 $40.00 Subtotal $ $ Labor at $15.00 per hour Reinhardt, Dave $1, Kilzer, Jason $1, Nation, Nick $1, Shriver, Matt $1, Subtotal $5, Total $ $5, Table 13: Revised Financial Requirements Item W/O Labor With Labor Miscellaneous Parts & Materials $20.00 $20.00 Device Components $65.94 $65.94 Project/Poster Printing $0.00 $0.00 Subtotal $85.94 $85.94 Labor at $15.00 per hour: Reinhardt, Dave $1, Kilzer, Jason $1, Nation, Nick $1, Shriver, Matt $1, Subtotal $5, Total $85.94 $5, Table 14: Final Financial Requirements Item W/O Labor With Labor Miscellaneous Parts & Materials $20.00 $20.00 Device Components $66.90 $66.90 Project/Poster Printing $0.00 $0.00 Subtotal $86.90 $86.90 Labor at $15.00 per hour: Reinhardt, Dave $2, Kilzer, Jason $2, Nation, Nick $2, Shriver, Matt $3, Subtotal $10, Total $86.90 $10,

33 The difference in the financial requirements can be attributed to the increased number of hours spent on the tasks of the project. 3.2 Schedules Contained in the next two sections are the two types of Gantt charts that were used in the project. The detailed deadlines gantt charts show the order in which tasks are supposed to be complete Detailed Gantt Chart The Gantt chart on the next page shows the calendar for the project and how it changed over time. The three major differences between the original, revised, and actual schedule was the product implementation, product documentation, and product testing. The reason for the difference in the product implementation is because parts were ordered later than originally planned, and they took a long time being delivered. Once the parts were delivered it took longer than expected to build the components of the PWM system. This in turn pushed back the testing phase of the project. Without the components built there was nothing to test until they were completed. The product documentation was also pushed back because not all the components were finished and determined that they were functional. 27

34 Figure 24: Combined Detailed Gantt Chart 28

35 3.2.2 Deadlines Gantt Chart Figure 25: Deadlines Gantt Chart 29

36 4.0 Closure Materials In closing, below is the contact information for all group members, advisor, and client. A closing summary is also included in this section. 4.1 Project Evaluation This section will discuss degree of success of the project. Table 15 shows various milestones and their degree of achievement: Table 15: Project Evaluation Milestone Degree of Achievement 1. PVFD Project partially met A. Produce PVFD partially met 1) Develop Design for PVFD fully met 2) Simulation of PVFD partially met 3) Implementation of PVFD fully met Comments Some milestones were fully achieved while others were not Some of the items below were attained with others only partially attained or not at all The design met all technical requirements, when simulation test were complete Full simulation was completed. However two programs were needed to complete simulation The design was completely implemented into a prototype 4) Technical requirements satisfied by prototype partially met See items below. a) Provide minimum power output of 75 W fully met b) Output continuously selectable Output is selectable between 57.5 exceeded between 58 and 62 Hz and 62.5 Hz. c) Short-term stability less that.01% not attempted No feasible way to test this milestone d) LCD frequency display accurate to PVFD has a frequency display not met.001 Hz accurate to 0.01 Hz. B. Portable strobe system not attained In Table 15, note that items listed under and indented determined the degree of achievement for the less indented milestone. For example, the degree of achievement for milestone 4. depends on what level milestones a), b), c), and d) are achieved. A PVFD was produced at the end of this product that allowed to used to change the outputted power frequency with an accuracy of.01 Hz. However not all of the milestones were fully achieved and thus the project was only partially successful. 4.2 Commercialization Currently on the market VPInductries produces a Synchronous Drive System (SDS) that is very similar to the device this project produced. This device lists for $1000. The PVFD has nearly 30

37 the same functionality and will list for well less than $1000. The market for the PVFD is the same as the market for the SDS, which is people interested in precision control of a synchronous motor. The list price calculated in the following table was under the assumption of a minimum 600 units being procured. Table 16 shows the drop in price when mass quantities are ordered. Table 16: Summation of Parts for PVFD Single Quantity Price Mass Quantity Price Mass Quantity Total Part Quantity Device XR Monolithic Function Generator $2.80 $1.60 $3.20 Various 12 Resistor $0.05 $0.04 $0.48 Various 4 Potentiometer $0.58 $0.36 $1.44 Various 5 Capacitor $0.09 $0.04 $0.20 STGW30NC60W 4 IGBT $4.34 $2.59 $10.36 ua741 3 Operational Amplifier $0.15 $0.07 $0.21 N/A 1 Frequency Counter $ $67.50 $67.50 PT-65C 1 Power Supply $42.00 $40.00 $40.00 N/A 1 Transformer (approx. values) $ $68.00 $68.00 N/A 1 Strobe Light $18.35 $11.01 $11.01 Total $ $ $ The cost to build a prototype is $ (this number is not what it cost the group as various items were donated). The estimated cost to mass produce the PVFD is $ This price is significantly lower than $1000. The $ does not include labor or manufacture costs. With this in mind the PVFD could sell for $300 and compete with the SDS and make a significant profit, approximately $100 per device. 4.3 Recommendations for Additional Work This section discusses some possible upgrades to the PVFD what would make the product even more useful. The PVFD is designed specifically for an AC synchronous motor, and because of that we are able to supply an output voltage less than the standard 110 VAC. We can get by with this because synchronous motors depend solely on the frequency of the mains. However, the lower output voltage created higher currents and higher current reduce efficiency. Some additional design work is needed to be able to output 110 VAC. The strobe light is currently included as a separate RPM measuring instrument. Some additional work could be done that gives the user the option of seeing the speed of the motor they are controlling and then even the ability to control the RPM would be more useful. A second LCD screen would be required along with the additional changes of circuitry to the strobe light and the PVFD module would be needed to make this enhancement a reality. 4.4 Lessons Learned Testing and problem solving was a strength of this group. When developing the circuitry to produce the gate signals many small problems arose. For instance the triangle wave generator 31

38 circuit did not produce a triangle wave with the correct amplitude. The group was able to use an op amp to increase the amplitude by a factor of 2.2. Producing clean sine and triangle waves proved to be a great challenge. The XR-2206 chip did not produce the cleanest waveforms. This problem added more complexity to the project as another set of filters were required, however these filters did not produce a wave no voltage ripple. The group was still not content with the sine and triangle waveforms that are being used in the project. The technology of pulse width modulation was foreign to three group members with one group member with a small amount of understanding. The group learned how to create small signal sine and triangle waves. No one in the group had ever dealt with IGBT s. The operation of the IGBT bridge was a learning experience for the group because the gate signals had have a certain amount of delay in the rise/fall time so that the IGBT s would not short out. The group leader needs to lay down specific expectations of what each group member is expected to complete. The group has learned that it is important to speak clearly and make sure everyone (team leader, group members, advisor, vendor) is on the same page. The group did not spend enough time at the beginning of the project developing ideas and constructing a solid project plan. Because of the lack of a good project plan the group had very little direction for a couple months. Instituting a minimum hours worked per week rule would have made the group work harder instead of slacking when there was nothing immediately due. 4.5 Risk and Risk Management Table 17 shows the anticipated risks developed at the beginning of the project and then the planned management. Table 17: Anticipated Risks and Action Plan Potential Risks Cost (Over Budget) Lazy Group Member Design does not meet Client s specifications Planned Management The group was given $300 ($150 - senior design; $150 - client). If the cost was less than $75 over budget the group members would chip in some money. If the project cost was going to be over $375 then a lower cost opportunity must be found. If no lower cost option available then senior design coordinator would be contacted. In the event one or multiple group members are not carrying their load of the project s will be sent to them to explaining what there next responsibility is and when it is due. Faculty advisor will also be contacted. The client would be contacted and the lack of performance would be discussed. Input for client will determine where the project is to go. The last two items in Table 17 were encountered. Actually for the second one the team leader started sending s where group member responsibilities and due dates were laid out. Sending these s was helpful because then the group members knew what was expected of then, however only slightly did this help our group get work done. The group discussed with Jim 32

39 Walker that our design was not going to give frequency precision to.001 Hz. Jim explained that.1 Hz would actually be sufficient. Jim also explained that the stability requirement of.01% was not important to him. Table 18: Unanticipated Risks and Resultant Management Unanticipated Risks Strobe light difficulty Difficulty is producing clean sine and triangle waveforms Attempts to Manage Risks The group found a simple "Do It Yourself" strobe light design with complete parts list and schematics. The parts for the strobe never arrived from the first vendor that they were ordered from. After 6 weeks of waiting a second vendor was selected and the parts were ordered again. The group developed the low pass filters to be placed after the waveform generator circuits. The filters helped out slightly and were made apart of the final product. Difficulty of producing output voltage of 110 VAC Realization that out design had overlooked how to change our variable frequency sine wave into 110 VAC. Synchronous motors do not depend on voltage therefore the group decided to just get as close to 110 VAC as possible and monitor the higher currents. The group determined that the strobe light portion of the project was going to be the least demanding and thus was pushed to the back burner for a while. This portion of the project should have been started early first semester as opposed to the end of first semester and then the delay and problems with parts could have been worked out with time to spare. The IC s producing the sine and triangle waveforms were not of as high of a quality as was expected. More time and money may have allowed us to seek another method to produce these waveforms, however considering the situations this risk was managed adequately. The output voltage not being 110 VAC is satisfactory, but not ideal. The group should have planned better so this would not happen. 4.6 Project Team Information This is the contact information for the precision variable frequency drive design group, clients and faculty advisor. Client Information: Name Jim Walker Mailing Address 112 North Dakota Ave. Ames, IA Telephone Number Address heathman@care2.com Faculty Advisor Information: Name Office Mailing Address Ajjarapu Venkataramana 1122 Coover Ames, IA Valley View Rd. 33

40 Ames, IA Office Telephone Number Home Telephone Number Fax Address Student Team Information: Name Major Mailing Address Jason Kilzer Electrical Engineering 1302 Woodstock Ames, IA Telephone Number Address Name Nick Nation Major Electrical Engineering Mailing Address 309 Lynn Ave Apt. 4 Ames, IA Telephone Number Address nnation@iastate.edu Name David Reinhardt Major Electrical Engineering Mailing Address 221 Sheldon Apt. 4 Ames, IA Telephone Number Address drein@iastate.edu Name Major Mailing Address Matt Shriver Electrical Engineering 311 Maple Friant Ames, IA Telephone Number Address mshriver@iastate.edu 34

41 4.7 Closing Summary Some applications of synchronous motors require precision speed control. For instance the speed of a record players turntable is critical to assure the correct sound it played. The purpose of this group is to create a precision variable frequency drive that could be used to control any low power synchronous motor. Pulse width modulation (explained in section ) is used to change the frequency of the power outputted and an IGBT bridge (explained in section ) to provide control and power electrical separation. The PVFD prototype is able change the frequency of the power outputted with precision of 0.01 Hz, thus the project is considered a success. Refer to Table 15 on page 26 to see a more detailed explanation for the milestones for success and their level of achievement. The powering of the PVFD is an issue that is still being worked out but once that problem is taken care of, the necessary documentation will be added to this report and included in the final bound copy. 35

42 4.8 References 1. alternating current. (n.d.). Dictionary.com Unabridged (v 1.1). Retrieved March 29, 2007, from Dictionary.com website: current 2. direct current. (n.d.). Dictionary.com Unabridged (v 1.1). Retrieved March 29, 2007, from Dictionary.com website: current 3. liquid crystal display. (n.d.). Wikipedia, the free encyclopedia. Retrieved March 29, 2007, from Reference.com website: 4. variable-frequency drive. (n.d.). Wikipedia, the free encyclopedia. Retrieved March 29, 2007, from Reference.com website: 5. integrated circuit. (n.d.). Dictionary.com Unabridged (v 1.1). Retrieved March 29, 2007, from Dictionary.com website: circuit 6. insulated gate bipolar transistor. (n.d.). Wikipedia, the free encyclopedia. Retrieved March 29, 2007, from Reference.com website: 7. Astrodyne. Open Frame Switchers. Retrieved on March 25, 2007 form 8. Vinyl Engine. DIY Turntable Strobe. Retrieved on November 6, 2006 from 36

43 Appendix A Parts List The following is a complete parts list of the precision variable frequency drive project. Table 19: Complete Parts List Part XR kΩ 10kΩ 2kΩ 1uF 10uF Sine Wave Generator Parts Device Monolithic Function Generator (Exar) Resistor Potentiometer Potentiometer Capacitor Capacitor Triangle Wave Generator and Amplifier Parts Part Device XR-2206 Monolithic Function Generator (Exar) 680Ω Resistor 10kΩ Resistor 6.8kΩ Resistor 3.3kΩ Resistor 1.5kΩ Resistor 500kΩ Potentiometer 100kΩ Potentiometer 1uF Capacitor 10uF Capacitor ua741 Operational Amplifier Part STGW30NC60W STGW30NC60W STGW30NC60W STGW30NC60W Part 22Ω 100uF IGBT Bridge Parts Device IGBT IGBT IGBT IGBT Low Pass Filter Parts Device Resistor Capacitor Triangle Wave Generator and Amplifier Parts Part Device XR-2206 Monolithic Function Generator 680Ω Resistor 10kΩ Resistor 37

44 6.8kΩ 3.3kΩ 1.5kΩ 500kΩ 100kΩ 1uF 10uF ua741 Resistor Resistor Resistor Potentiometer Potentiometer Capacitor Capacitor Operational Amplifier Part CD4060B CD4013B CD4013B BC327 N/A N/A MHz 5.2pF 22pF 10pF 100pF 470uF 1MΩ 1kΩ 56kΩ PT-65C Part List For Strobe Light Device IC - Binary Ripple Counter Dual D-flip-flop Dual D-flip-flop Silicon PNP Transistor Diode Diode Quartz Crystal Capacitor Capacitor Capacitor Capacitor Capacitor Resistor Resistor Resistor Push Button Switch 9V Alkaline Battery Wood Case 16-pin DIP Socket 14-pin DIP Socket Frequency Counter 10:1 300W Transformer Power Supply 38

45 Appendix B Circuit Schematics 39

46

47

48 Appendix C Testing Forms 40

49

50

51 Appendix D Exar XR-2206 Datasheet 41

52 ...the analog plus company TM XR-2206 Monolithic Function Generator FEATURES Low-Sine Wave Distortion, 0.5%, Typical Excellent Temperature Stability, 20ppm/ C, Typ. Wide Sweep Range, 2000:1, Typical Low-Supply Sensitivity, 0.01%V, Typ. Linear Amplitude Modulation TTL Compatible FSK Controls Wide Supply Range, 10V to 26V Adjustable Duty Cycle, 1% TO 99% APPLICATIONS Waveform Generation Sweep Generation AM/FM Generation V/F Conversion FSK Generation Phase-Locked Loops (VCO) June GENERAL DESCRIPTION The XR-2206 is a monolithic function generator integrated circuit capable of producing high quality sine, square, triangle, ramp, and pulse waveforms of high-stability and accuracy. The output waveforms can be both amplitude and frequency modulated by an external voltage. Frequency of operation can be selected externally over a range of 0.01Hz to more than 1MHz. The circuit is ideally suited for communications, instrumentation, and function generator applications requiring sinusoidal tone, AM, FM, or FSK generation. It has a typical drift specification of 20ppm/ C. The oscillator frequency can be linearly swept over a 2000:1 frequency range with an external control voltage, while maintaining low distortion. ORDERING INFORMATION Operating Part No. Package Temperature Range XR-2206M 16 Lead 300 Mil CDIP -55 C to +125 C XR-2206P 16 Lead 300 Mil PDIP 40 C to +85 C XR-2206CP 16 Lead 300 Mil PDIP 0 C to +70 C XR-2206D 16 Lead 300 Mil JEDEC SOIC 0 C to +70 C Rev EXAR Corporation, Kato Road, Fremont, CA (510) (510)