Paper 175
Contents
1. Proceedings of The 2008 IAJC IJME International Conference ISBN 978 1 60643 379 9 Paper 175 ENG 105 Application of a Software Configurable Digital Servo Amplifier to an Electric Machine Control Course Shiyoung Lee Ph D Pennsylvania State University Berks Campus sul28 psu edu Abstract The various applications of the three phase permanent magnet brushless dc motor PMBDCM in the industry are increasing The main purpose of this paper is to describe the application of a new technology to academic electric machine control and or power electronics drive courses An easy method for the implementation of a fully software configurable digital servo amplifier to drive a three phase PMBDCM is presented in this paper This developed servo amplifier may be suitable for an electric machine control course The change of drive configuration requires additional development time and cost especially in control software modification which in turn depends on the specific application The highlight of the paper is the GUI Graphical User Interface based control software Pro Motion setup for implementation of a software configurable digital servo amplifier The principle of the operation of the three phase PMBDCM is discussed first and then the requirement to develop three different types of servo amplifier such as velocity position and torque servo amplifiers to drive the three phase PMBDCM are explained The details of a selected motor control integra2. application of an operational amplifier Electromagnetic Interference EMI or Radio Frequency Interference RFI The EMI RFI issue directly relates to the clock and PWM frequency in the proposed servo amplifier The proper management of the printed circuit board PCB design is required to minimize the EMI RFI effect It is important to address this issue and examine the PCB design The grounding technique the use of power and ground planes in multilayer PCB design and the elimination of ground loop may be worthy topics for discussion Proceedings of The 2008 IAJC IJME International Conference ISBN 978 1 60643 379 9 Conclusion This paper addresses the feasibility of employing the digital PMBDCM drive in electric machine control and or power electronics drive courses The low cost and time saving way to develop a software configurable digital servo amplifier for the PMBDCM drive was confirmed with a velocity servo drive example The MC73110 developer s kit is extremely useful in implementing a software configurable digital servo amplifier without spending high development costs and time The attainable teaching components with the proposed PMBDCM digital servo amplifier are the characteristics of the PMBDCM the distinction between sinusoidal and trapezoidal drive and the uniqueness of Hall sensor and encoder based commutation methods The difference between three phase full and half bridge power circuits the assorted gate drive circuitry
3. look attractive for educational application because they provide not only hardware platforms but also dedicated setup software The MC73110 based development kit may be suitable for the fast and easy development of the PMBDCM drive instructional components This paper proposes the MC73110 motor control IC based developer s kit for this purpose This kit was chosen for the easy and cost effective implementation of the instructional component of the PMBDCM drive in the electric machine control course The PMBDCM drive is increasingly popular in the industry sector but it has not been integrated into an academic curriculum Consequently it is the logical choice for incorporation into an academic course that will prepare students for industry The development kit provides a hardware platform that contains all necessary analog and digital circuits on one PCB and user friendly GUI based configuration software The two volume user manual is also a good resource to use in the design of any size and type of PMBDCM drive It is suitable and timely to investigate the incorporation of the PMBDCM drive into the electric machine control course The design of the PMBDCM drive has two major tasks one in hardware and another in software design To accomplish both design tasks one should understand its principle of operation The hardware design could be classified as but not limited to power circuitry that includes a power switching circuit analog and or digital se
4. motor PMDCM the rotor contains permanent magnets and the motor windings are mounted on the stator 7 The PMBDCM does not have brushes that are required for commutation of the PMDCM Therefore a maintenance free motor drive system is possible with the PMBDCM To drive the PMBDCM an electronic commutation circuit is required This paper is concerned only with the position sensor based commutation therefore the two common Proceedings of The 2008 IAJC IJME International Conference ISBN 978 1 60643 379 9 0 180 360 540 Hall A Hall B Hall C Electrical Degree Figure 1 Three phase Hall sensor timing chart with 120 angle separation a CW direction b CCW direction Figure 2 Measured Hall signals in CW and CCW direction at 1500r min CH1 Hall A CH2 Hall B CH3 Hall C Vertical 2V div Time 5ms div position sensing techniques are discussed The first one is the Hall effect sensor which is the most cost effective method of rotor position sensing The timing diagrams of three typical Hall sensors with 120o angle separation are shown in Figure 1 The experimental waveforms of the three Hall signals in both clockwise CW and counterclockwise CCW directions of motor rotation are shown in Figure 2 The direction of rotation is viewed at the motor shaft The sequences of the Hall signals are Hall A Hall B Hall C in the CW direction and Hall B Hall C Hall A in the CCW direction The second method uses the optical encoder The
5. E International Conference ISBN 978 1 60643 379 9 Table 1 Three different operation modes leg The generated PWM output signals are symmetric waveforms they are synchronized to the master PWM output switching frequency at 20kHz The MC73110 can be configured as different types of amplifiers as summarized in Table 1 Most applications may fall under one of the three standard configurations explained below Torque Amplifier The torque command will be either an analog signal or an SPI digital data stream The typical target application of this mode may be the position servo with external position loop and position feedback The position feedback signal can be analog with analog feedback devices or digital with a microprocessor One example of the position feedback is the potentiometer which provides continuously varying voltage that is proportional to the rotor position The torque amplifier can be a standalone or can employ a host processor The MC73110 motor control IC has a 20 kHz digital current loop The two motor current feedback signals CurrentA B are required to close the current loop Velocity Amplifier This amplifier can be another standalone application with the velocity loop enabled The MC73110 has an internal digital velocity loop with a rate frequency of 10 kHz The velocity command signal will be the same as for the torque amplifier the difference is that the command signal represents velocity rather than torque
6. M generation for three phase full bridge power circuit and three signal PWM for single switch per phase power circuit configuration Hall or quadrature encoder based commutation digital current and velocity loops profile generation emergency stop analog velocity command and RS 232 serial communication port for example Both the six step and sinusoidal commutation methods are possible with this IC But a quadrature encoder is required in addition to the Hall effect sensors to implement the sinusoidal drive The details of the six main functional modules in the MC73110 IC are listed below 3 Profile Generator Module This module generates a velocity and acceleration bounded profile by using the serial port commands The instantaneous desired velocity value is put out to either the velocity integrator or the velocity loop module A host processor microprocessor or personal computer is needed to utilize this module Velocity Integrator Module A desired velocity value from the profile generator module or an external analog signal AnalogCmd or a synchronous serial digital 16 bit word data stream serial peripheral interface SPI bus will be applied to this module This value integrates into an instantaneous desired position which is compared with the actual position from the encoder to develop either desired velocity or torque Velocity Loop Module Next a desired velocity command emerges into this module The velocity command wi
7. a variety of current sensing methods the aspects of velocity and current PI controllers and the various analog signal conditioning methods are also suitable References 1 Rui Hong Chu Dylan Dah Chuan Lu and S Sathiakumar Project Based Lab Teaching for Power Electronics and Drives IEEE Trans on Education Vol 51 No 1 Feb 2008 pp 108 113 2 Jon Titus Kits Jump Start Motor Applications Design News August 13 2007 3 Performance Motion Devices Inc MC73110 Advanced 3 phase Motor Control IC Product Manual Revision 1 4 October 2004 4 Performance Motion Devices Inc MC73110 Advanced 3 phase Motor Control IC Developer s Kit Manual Revision 1 4 August 2005 5 Rovert S Balog et al Modern Laboratory Based Education for Power Electronics and Electric Machines IEEE Trans on Power Systems Vol 20 No 2 May 2005 pp 538 547 6 Joshua M Williams et al Versatile Hardware and Software Tools for Educating Students in Power Electronics IEEE Trans on Education Vol 47 No 4 Nov 2004 pp 436 445 7 R Krishnan Electric Motor Drives Modeling Analysis and Control Prentice Hall 2001 Biography SHIYOUNG LEE is currently an Assistant Professor of Engineering Technology at Pennsylvania State University Berks Campus Reading PA He teaches Programmable Logic Controller PLC Linear Electronics and Electric Circuits Laboratory courses His research interest
8. ble The PMBDCM under testing is the Maxon EC Max 30 order number 272769 A PMDCM is connected back to back with the PMBDCM to form a motor generator set The PMDCM and PMBDCM specifications are listed in Table 2 The pulse width modulated motor terminal voltage between Phase A and B and Phase A line current is shown in Figure 12 Since the commutation is Hall based trapezoidal six step the measured current waveform resembles the trapezoidal waveform except in the zero crossing area and top flat portions in both half cycles a Current PI b Motion Figure 10 Current PI and motion settings Proceedings of The 2008 IAJC IJME International Conference ISBN 978 1 60643 379 9 Figure 11 Experimental setup with the MC73110 based PMBDCM drive Table 2 Specifications of the PMBDCM and PMDCM under testing PMBDCM Maxon EC Max 30 272769 PMDCM Moog Nominal Voltage V 36 0 Nominal Voltage V 26 0 No Load Speed r min 9160 No Load Speed r min 10346 No Load Current mA 73 20 Peak Torque oz in 50 Nominal Speed r min 7080 Continuous Torque oz in 7 5 Nominal Current mA 97 60 Torque Sensitivity oz in A 3 42 Torque Constant mNm A 36 8 Back EMF V rad s 0 024 Speed Constant r min V 259 Mechanical Time Constant ms 6 98 Figure 12 PMBDCM terminal voltage VAB and Phase A line current with trapezoidal commutation Vertical CH1 25V div CH4 0 1A div center zero Horizontal 5ms div PMBDCM Encode
9. d in both half cycles as shown in Figure 4 The Hall signals provide position information of the flat top portions of the back EMF in both half cycles Based on the position information it can be seen that the pulse width modulated motor voltage hence the motor current is applied to generate the motor torque Introduction of the MC73110 Motor Control IC For the fast changing motor drive technology in industry the provision of a new motor control IC was beneficial in developing a digital servo controller without time consuming effort spent on control software development The MC73110 motor control IC has developed into an advanced single chip single axis device that can be used to implement an intelligent three phase PMBDCM controller based on FPGA and ASIC technologies 3 4 It is packaged in a 64 pin thin quad flat pack TQFP measuring 12 mm by 12 mm and operates on 3 3V It can be operated in internal velocity profile mode velocity mode with an external analog digital velocity command signal or torque mode with an external torque command signal It also can be operated as a standalone controller using pre programmed parameters stored onto chip flash memory or through the RS 232 serial port using the Pro Motion GUI setup software The simplified functional block diagram of the MC73110 is shown in Figure 5 The various functions useful for the development of the PMBDCM drive are embedded in the MC73110 IC These functions include the three phase PW
10. e GetLoopError instruction makes monitoring of discrete velocity and torque loop error values possible To implement a position servo controller a position loop can be added externally to the velocity command It can be realized with few external analog components or with a tiny microcontroller The velocity loop must be disabled to accommodate an external position loop Proceedings of The 2008 IAJC IJME International Conference ISBN 978 1 60643 379 9 RS 232 Serial Communication Serial communication is an industry standard means of transmitting and receiving data between a computer and a peripheral device It is one of the most popular communication methods because the RS 232 serial port is installed on most computers It should be noted that the MC73110 based servo amplifier could be configured as a standalone unit In this case the necessary control parameters should be downloaded into an on chip flash memory in the MC73110 IC Current Sensing Circuit To close the current loop the MC73110 requires two motor phase currents phases A and B information The phase C current is generated internally by combining those currents Various current sensing techniques can be discussed the passive way with a current sensor resistor and Hall sensor based current sensing IC The different implementation methods of the analog signal processing circuit need to be discussed along with the current sensing circuitry The analog signal processing circu
11. f the heat sinking of power switching devices should be addressed with power circuit topologies PWM Method The various PWM strategies to generate PWM gate signals to drive three phase power circuits can be introduced Among them the symmetric three phase PWM method is implemented in the MC73110 IC Back EMF Types and Commutation Method Two types of commutation strategy can be introduced six step trapezoidal and sinusoidal Six step commutation can be implemented with Hall position feedback sensors only It is suitable to the PMBDCM that has trapezoidal back EMF waveform On the other hand the sinusoidal commutation needs a quadrature encoder in addition to Hall position sensors This method is applied to the PMSM with sinusoidal back EMF waveform But the different effects can be investigated when both commutation methods are applied to the PMBDCM Control Loop Closure The velocity and torque loops are embedded on the MC73110 The basic open loop and closed loop control systems can be demonstrated to the class The observation of effects when closing either or both control loops will be an interesting task for students Also the effects of the various proportional P and integral I gain values in the control loop can be observed through experiment Because of the lack of graphical representation capability in Pro Motion setup software the continuous monitoring of various control variables is not possible Instead as an example th
12. in the torque amplifier The Hall signal or the encoder or the tachogenerator can be used as the velocity feedback Intelligent Motion Controller This configuration needs a host processor or computer to generate a command signal through the profile generator In this case the MC73110 works as an intelligent programmable motion controller The command signal will be applied through the RS 232 serial port Operation Mode Modules Encoded Minimal Connections Torque Current Loop Hall A B and C CurrentA B QuadA B sinusoidal commutation only DigitalCmdClk Data or AnalogCmd Velocity Current Loop Velocity Loop Hall A B and C CurrentA B QuadA B sinusoidal commutation only or Tachometer DigitalCmdClk Data or AnalogCmd Intelligent Motion Controller Current Loop Velocity Integrator Profile Generator Hall A B and C CurrentA B QuadA B SrlXmt Rcv Proceedings of The 2008 IAJC IJME International Conference ISBN 978 1 60643 379 9 Figure 6 Simplified block diagram of the proposed velocity servo amplifier Design Example of a Digital Velocity Servo Amplifier To prove the capability of the MC73110 a digital velocity servo amplifier was designed The experimental results will be discussed in this section The major benefit of the servo amplifier design used with the MC73110 is the flexibility of control loop configurations and the setup of its parameter values The previously mentioned amplifier types can be software configu
13. incremental encoder is widely used due to its lower cost than the absolute type However the optical encoder provides better resolution of position data than the Hall sensor therefore making precise control of the PMBDCM possible There are two types of permanent magnet brushless dc motors which depend on their back electromotive force EMF waveforms 7 The PMBDCM has the trapezoidal six step back EMF waveform The one with the sinusoidal back EMF is called the permanent magnet synchronous motor PMSM The PMSM provides nearly zero torque ripples In this paper only the PMBDCM with Hall sensor based commutation will be discussed A simplified three phase full bridge power circuit for the PMBDCM is shown in Figure 3 The relationships between the three phase back EMF motor current and air gap power are shown in Proceedings of The 2008 IAJC IJME International Conference ISBN 978 1 60643 379 9 Figure 3 Three phase full bridge power circuit for PMBDCM drive Figure 4 Relationship between back EMF motor current and air gap power for three phase PMBDCM drive Proceedings of The 2008 IAJC IJME International Conference ISBN 978 1 60643 379 9 Figure 4 7 The trapezoidal back EMF ea b and c has a constant magnitude of Ep during 120 electrical degrees in both the positive and negative half cycle The air gap power Pa and the electromagnetic torque are both continuous when applying motor current ia b and c during the same perio
14. is digital control of motor drives and power converters He is a senior member of IEEE and a member of ASEE
15. it for the current sensor varies widely depending on the current sensing technique The following topics are relevant to broaden the coverage further IC Packaging Type Various package types of modern surface mount devices SMDs can be introduced to the class The MC73110 IC is built on a 64 pin TQFP Some of the IC package types that may be found on the MC73110 development board are small outline package SOP small outline integrated circuit SOIC thin shrink small outline package TSSOP and discrete packaging D2PAK for power switching devices Protection of the Dc Voltage Polarity Reversal The required voltage type for the MC73110 development kit is dc The addition of the protection circuit against the dc polarity reversal is a must for practical application Regenerative Braking Circuit A regenerative braking circuit should be included for the four quadrant operation of the servo amplifier to dissipate the regenerative energy flows back to the bus when the PMBDCM operates in regeneration mode It can be easily implemented with a comparator with the bus voltage sensing circuit a power switching device N type MOSFET and a power resistor to dissipate the regenerated energy Level Shift Circuit The MC73110 is powered with 3 3V Therefore the various higher input signal levels such as 5V and 10V should be converted into 3 3V A level shift circuit with an operational amplifier can be addressed as an example of a real world
16. mbinations are shown in Figure 9 The one combination of each group of motor phase windings and Hall signals should provide an even response for the bipolar command signal The setup of velocity loop parameters depends on feedback devices as shown in Figure 8 b The allowable velocity feedback sources are analog tachogenerator encoder and Hall signals The values of PI parameters will be selected by trial and error through the command window The GetLoopError instruction gives the value of the velocity error The optimum values of PI parameters can be found by observing the minimal change in the returning velocity error values in either positive or negative polarity Since the MC73110 does not have the capability of graphical representation of error values this procedure may be tedious and time consuming The same procedure could be applied to the current loop to find out optimum PI parameter values as shown in Figure 10 The motion window provides for the selection of servo loops and motor dynamics For the standalone application such as the velocity servo amplifier example in this paper the velocity command source should be analog The typical analog velocity command value will be the industry standard 10V dc voltage The experimental setup is shown in Figure 11 The velocity command is 10V dc voltage labeled as Analog Command in front The communication between the MC73110 and the Pro Motion software is performed with an RS 232 serial ca
17. nsor circuits and controller circuitry The development of application specific software for a motor drive is not always an easy task Fortunately the MC73110 based development kit provides user friendly drive configuration software for easy setup of the desired type of the PMBDCM drive In this paper the technical concepts of the PMBDCM and its drive are explained first to provide a fundamental background of the overall drive system suitable to the conventional electric machine control and or power electronics courses Second the characteristics of the MC73110 motor control IC will be explained Principle of Operation of the PMBDCM Drive The PMBDCM is an electronically commutating permanent magnet motor The applications of this motor are growing Because of its inherent variable speed drive nature it is widely used in white goods automobile and machine building industries The commutation circuit for the three phase PMBDCM can be implemented with discrete components or dedicated control IC The design with discrete components provides many insights on the commutation circuit for students at the same time it requires lots of time and effort to build the hardware and to troubleshoot The dedicated IC approach looks promising because little or no additional circuitry is required Some manufacturers even offer dedicated setup software to use their IC The mechanical structure of the PMBDCM is the reverse of the conventional permanent magnet brushed dc
18. o the Hall signals This module will remain enabled at all times Current Loop Module The target current for two motor phase coils PhaseA and PhaseB will be applied to this module It uses two sensed analog feedback signals CurrentA and CurrentB to develop three PWM output values for a three phase PMBDCM When the MC73110 operates the motor in the voltage mode this module can be disabled Motor Output Module The desired voltage for each of the three motor phase coils will be applied to this module Then it generates the PWM signal in either three signal mode one signal per phase or six signal mode high side and low side signals for each phase Position Feedback and Commutation Angle DigitalCmdData DigitalCmdClk Profile Generator Velocity Integrator Velocity Loop A D 10 bit SPI 16 bit Velocity Command 16 bit A D 10 bit AnalogCmd QuadA QuadB Index Velocity Motor Command Commutation Module Hall Sensors Reset Estop PhaseA PhaseB Motor Output Module 3 or 6 signal output Digital Current Loop Module A D 10 bit CurrentA CurrentB PhaseA PhaseC PhaseB SCI Command Processor Flash User Configuration Storage SrlEnable SrlXmt SrlRcv Serial EEPROM I2CData I2CClk PWM Output Disable 3 Signal PWM 50 50 Output 6 Signal PWM Output with Shoot through Delay Amplifier Disable Current Command 16 bit Proceedings of The 2008 IAJC IJM
19. r PMDC Generator RS 232 Cable 10V Analog Command Proceedings of The 2008 IAJC IJME International Conference ISBN 978 1 60643 379 9 Teaching Components with the Proposed Servo Amplifier for the PMBDCM The proposed digital servo amplifier based on a highly integrated MC73110 motor control IC provides various teaching components to enhance the electric machine control and or power electronics drive courses Possible teaching topics and their brief explanations are listed below Power Circuit and Gate Drive Circuit The MC73110 IC supports not only conventional three phase full bridge power circuits with six power switching devices but also three phase half bridge power circuits with three power switching devices Further a three phase half bridge power circuit can be applied to the switched reluctance motor SRM drive with Hall position feedback sensors In this case the motor winding of SRM or PMBDCM is preferably Y connection with the center point accessible Usually the half wave power circuit produces less output power than the full wave power circuit 7 The gate drive for the high side switching devices requires isolation when an N type metal oxide field effect transistor MOSFET device is used By using a P type MOSFET device the free of isolation of gate drive is possible The various aspects of the types of power switching devices and gate drive selection will be attractive topics to be discussed in detail The method o
20. rable by using the interactive Windows based Pro Motion GUI software Since this software is royalty free the development of any industrial applications with MC73110 can be cost effective The simplified overall block diagram of the proposed velocity servo amplifier is shown in Figure 6 In this example the explanation of hardware connections will be omitted Rather the focus will be on the verification of software setup After completion of hardware setup and successful connection between the host PC and the MC73110 the MC73110 developer s kit will be activated first by invoking Axis Setup Wizard on the Pro Motion window 4 a Signal output b Signal sensing Figure 7 Signal output and sensing settings Proceedings of The 2008 IAJC IJME International Conference ISBN 978 1 60643 379 9 a Commutation b Velocity PI Figure 8 Commutation and velocity PI settings The first page of the wizard is the signal output setting window as shown in Figure 7 a The PWM output mode can be either three signal mode for a three phase half bridge power circuit or six signal mode for a three phase full bridge circuit The PWM dead time will activate only with six signal mode to prevent a possible shoot through fault in the phase leg It can be set to range from 0 to 12 s The PWM limit allows enough off time for charging the bootstrap capacitor in the bootstrap power supply for a high side switch The PWM output logic can be checked for the polarity in
21. ted circuit IC MC73110 from PMD Corp are introduced The various capabilities of the IC that make fast implementation of a software configurable digital servo amplifier possible are discussed The MC73110 IC is incorporated into the servo amplifier design resulting in an increased ease of use with software configuration To validate the software configurable digital controller a step by step design example to develop a velocity servo amplifier is completely explained and some of the test results are discussed As a conclusion suitable teaching topics based on the proposed software configurable PMBDCM drive for electric machine control and or power electronics drive courses are summarized Introduction Today numerous industrial applications are increasingly adopting the PMBDCM due to its inherent variable speed drive aspect Since the electronic commutation circuit is necessary to drive the PMBDCM it may not be easy to implement the PMBDCM drive In most cases it is time consuming and expensive to build instructional components for motor drives into existing electric machine control related courses 1 5 6 The implementation of hardware and software usually takes time to complete But many different types of development kits are available off the shelf for various types of motors 2 These development kits are aimed mainly at the Proceedings of The 2008 IAJC IJME International Conference ISBN 978 1 60643 379 9 industrial sector but they
22. th the current instantaneous velocity of the motor axis will be combined to determine a desired torque or voltage command in this module The desired velocity command will be generated from the profile generator module the velocity Proceedings of The 2008 IAJC IJME International Conference ISBN 978 1 60643 379 9 Figure 5 Simplified functional block diagram of MC73110 motor control IC integrator module the AnalogCmd or the digital SPI data stream The instantaneous velocity emerges from an analog signal through either the velocity pin of the chip or the quadrature encoder The velocity estimator provides velocity feedback to the digital PI velocity loop from the encoder or Hall feedback Users can disable this module easily with Pro Motion GUI In this case the MC73110 operates in either torque or voltage mode depending on the state of the current control module Commutator Module A single phase desired torque or voltage command will be applied to this module depending on whether the Current Loop Module explained below is enabled and this command will be vectorized into three phase commands one for each motor phase connection This module supports two commutation methods Hall based and sinusoidal The Hall signals when Hall based is selected must be connected through Hall1 Hall2 and Hall3 pins When the sinusoidal commutation is selected the quadrature encoder data must be connected through the QuadA QuadB and Index pins in addition t
23. version of the gate drive logic signals The signal sensing window provides the necessary inversion of the polarity of feedback signals from Hall sensors and or an encoder During normal operation black dots in white circles blink indicating the change of signals through feedback sensors The default signal sense is set to active low The commutation setup window is shown in Figure 8 a The commutation mode can be trapezoidal with Hall sensor feedback or sinusoidal with encoder feedback The sinusoidal commutation mode may be effective with a PMSM to generate near zero torque ripples 7 The Open loop start button can be used to check the phasing of Hall signals and motor windings in open loop mode When the PMBDCM commutates properly it gives smooth motion in both CW and CCW directions of rotation This function is very useful during initial setup of Figure 9 Possible combinations of motor windings and Hall signals PH A PH B PH C S1 S2 S3 1 A B C H1 H2 H3 1 2 A C B H1 H3 H2 2 3 B A C H2 H1 H3 3 4 B C A H2 H3 H1 4 5 C A B H3 H1 H2 5 6 C B A H3 H2 H1 6 Motor Phase Winding Hall Effect Sensor Proceedings of The 2008 IAJC IJME International Conference ISBN 978 1 60643 379 9 matching Hall signals with relevant motor windings Without this function all possible combinations of Hall signals and motor windings should be checked for correct phase matching The 36 possible co
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