3-Phase Brushless DC Motor Control 120
Contents
1. 20 2 5 Speed Detection ex Rem eee 21 2 6 Speed Control ii RT ie qup m imm m Reo a 21 2 6 1 Voltage control ne vues RP ERU UE M EUER AS 21 2 6 2 PIBDConttol out hd Eres ra aa Ba Te a RUN Nd 21 Chapter3 System 23 347 Configuration oii keen se A ERE Eu 23 3 2 Operational 24 3 3 Userlnterface iii MR xu 25 3 4 Peripheral 2 ecl cuya ae 26 Chapter 4 Design oor as IRI aa a Re Ex wl 27 4 1 MotorSpeed oin i er UEM Re e Ex ES 27 4 2 PlDOperation le mI Re ia E 27 4 3 Software Module 28 4 4 Processing Flow 2 Tee 29 Chapter5 Development 34 51 HardWare ool ee ee ates iat Me tay 34 A AA A A 34 User s Manual U18028EU1V1UMEO 9 10 User s Manual U18028EU1V1UMEO Figure 2 1 Figure 2 2 Figure 2 3 Figure 2 4 Figure 2 5 Figure 3 1 Figure 3 2 Figure 4 1 Figure 4 2 Figure 4 3 Figure 4 4 Figure 4 5 Figure 4 6 Figure 4 7 List of Figures Six Transistor Inve2. 26 Module and Main Processing mmm nenea nenea nn anna 29 User s Manual U18028EU1V1UME0 13 14 User s Manual U18028EU1V1UMEO Chapter 1 Introduction This document describes the specifications and design of a software package used with the Low Voltage Motor Control Evaluation System MC LVKIT 714 from NEC Electronics to drive a low voltage 3 phase brushless DC BLDC motor using 120 degree trapezoidal waves and Hall sensors for rotor position detection The software is supplied with the kit as open source and offers a quick start for anyone interested in learning and developing brushless DC motor hereafter referred as BLDCM control applications with NEC Electronics uPD78F0714 microcontroller MCU The code example described here supports NEC Electronics low voltage motor control starter kit when used with the MC CPU 78F0714 micro board MC LVKIT 714 For information about the electrical characteristics and hardware functions especially the motor control functions and setting of registers refer to uPD78F0714 Preliminary User s Manual U16928E For information about instruction functions refer to 78K 0 Series Instruction User s Manual U12326E For information on the Motor Control Evaluation System and its components consult the following documents Table 1 1 Documents Related to Motor Control Evaluation System Components MC CPU 78F0714 Micro Board Users Manual U17707E MC I O GENERAL Board U
3. Electrical Moni gt e 240 300 0 ng e 120 Degrees 3 a s Excited Phases U V W V W U V To drive the BLDCM the DC bus voltage is connected across two stator phases at any given time by turning on one upper and one lower transistor pair for 60 electrical degrees For a six element bridge there are six distinct switching configurations U V U W V W V U W U W V The BLDCM rotates 360 electrical degrees if the six switching configurations are changed sequentially at 60 degree intervals in synchronization with the rotor position After completing the six steps the sequence is repeated This method is called the 120 degree method because every switching element is turned on for 120 electrical degrees User s Manual U18028EU1V1UMEO 17 Chapter 2 Controlling a BLDCM 2 3 Excitation Pattern Figure 2 3 shows the six excitation patterns and the directions of the magnetic flux generated by the stator coils Figure 2 3 Excitation Patterns and Current Flux Directions Excitation pattern 1 Excitation pattern 2 Excitation pattern 3 Excitation jq Excitation pattern 5 Excitation y pattern 6 W gt U pattern 2 W gt V BLDOM revolves by the attraction and repulsion between the poles of the rotating magnetic field of the stator coils and the magnetic poles of the permanent magnet rotor The torque developed is at max imum when the angle
4. between the two magnetic poles is 90 degrees the position of the permanent magnet poles changes as the rotor revolves In the 120 degree method the commutation patterns are changed so that the angle between the mag netic pole of the rotor and rotating magnetic field of the stator is in a range of 60 to 120 degrees the direction of the stator flux depends on how the coils are wound There are two types of BLDCM type A with an interior rotor and type B with and exterior rotor Their principals of operation are similar 18 Users Manual U18028EU1V1UMEO Chapter 2 Controlling a BLDCM Figure 2 4 shows the attraction and repulsion between the poles of the rotating magnetic field and the permanent magnet Figure 2 4 Attraction and Repulsion of Magnetic Poles Attraction Rotating direction Type A Interior Type B Exterior Permanent Magnet Rotor Permanent Magnet Rotor The direction of rotation depends on the position of the rotor permanent magnet as well as on the combination and polarity of energized phases User s Manual U18028EU1V1UMEO 19 Chapter 2 Controlling a BLDCM 2 4 Position Detection For 120 degree or 6 step driving method the rotor position has to be known at 60 degree intervals Figure 2 5 shows an example of a magnetic pole position detection using Hall effect sensors Figure 2 5 Hall IC Angle o 60 120 180 240 300 360 V W Electromotive force of output pin To detect
5. infringement of patents copyrights or other intellectual property rights of third parties by or arising from the use of NEC Electronics products listed in this document or any other liability arising from the use of such products No license express implied or otherwise is granted under any patents copyrights or other intellectual property rights of NEC Electronics or others Descriptions of circuits software and other related information in this document are provided for illustrative purposes in semiconductor product operation and application examples The incorporation of these circuits software and information in the design of a customer s equipment shall be done under the full responsibility of the customer NEC Electronics assumes no responsibility for any losses incurred by customers or third parties arising from the use of these circuits software and information While NEC Electronics endeavors to enhance the quality reliability and safety of NEC Electronics products customers agree and acknowledge that the possibility of defects thereof cannot be eliminated entirely To minimize risks of damage to property or injury including death to persons arising from defects in NEC Electronics products customers must incorporate sufficient safety measures in their design such as redundancy fire containment and anti failure features NEC Electronics products are classified into the following three quality grades Standard Special and Speci
6. CES VOLTAGE APPLICATION WAVEFORM AT INPUT PIN Waveform distortion due to input noise or a reflected wave may cause malfunction If the input of the CMOS device stays in the area between Vi MAX and MIN due to noise etc the device may malfunction Take care to prevent chattering noise from entering the device when the input level is fixed and also in the transition period when the input level passes through the area between Vi MAX and MIN HANDLING OF UNUSED INPUT PINS Unconnected CMOS device inputs can be cause of malfunction If an input pin is unconnected it is possible that an internal input level may be generated due to noise etc causing malfunction CMOS devices behave differently than Bipolar or NMOS devices Input levels of CMOS devices must be fixed high or low by using pull up or pull down circuitry Each unused pin should be connected to Voo or GND via a resistor if there is a possibility that it will be an output pin All handling related to unused pins must be judged separately for each device and according to related specifications governing the device PRECAUTION AGAINST ESD A strong electric field when exposed to a MOS device can cause destruction of the gate oxide and ultimately degrade the device operation Steps must be taken to stop generation of static electricity as much as possible and quickly dissipate it when it has occurred Environmental control must be adequate When it is dry a humidifier sh
7. Electronics Corporation and also includes its majority owned subsidiaries 2 NEC Electronics products means any product developed or manufactured by or for NEC Electronics as defined above M8E 02 11 1 User s Manual U18028EU1V1UMEO For further information please contact NEC Electronics Corporation 1753 Shimonumabe Nakahara ku Kawasaki Kanagawa 211 8668 Japan Tel 044 435 5111 http www necel com America NEC Electronics America Inc 2880 Scott Blvd Santa Clara CA 95050 2554 U S A Tel 408 588 6000 800 366 9782 http www am necel com Europe NEC Electronics Europe GmbH Arcadiastrasse 10 40472 D sseldorf Germany Tel 0211 65030 http www eu necel com Hanover Office Podbielskistrasse 166 B 30177 Hannover Tel 0 511 33 40 2 0 Munich Office Werner Eckert Strasse 9 81829 M nchen Tel 0 89 92 10 03 0 Stuttgart Office Industriestrasse 3 70565 Stuttgart Tel 0 711 99 01 0 0 United Kingdom Branch Cygnus House Sunrise Parkway Linford Wood Milton Keynes MK14 6NP U K Tel 01908 691 133 Succursale Francaise 9 rue Paul Dautier B P 52180 78142 Velizy Villacoublay C dex France Tel 01 3067 5800 Sucursal en Espa a Juan Esplandiu 15 28007 Madrid Spain Tel 091 504 2787 Tyskland Filial Centrum Entrance S 7th floor 18322 T by Sweden Tel 08 638 72 00 Filiale Italiana Via Fabio Filzi 25 A 20124 Milano Italy Tel 02 667541 Branc
8. NEC User s Manual 3 Phase Brushless DC Motor Control 120 Degree Trapezoidal Drive with Hall Sensors for MC LVKIT 714 Motor Control Evaluation System Document No U18028EU1V1UMEO Date Published August 2006 NEC Electronics Corporation 2006 Printed in Germany CAUTION This is a Test and Measurement equipment with possibility to be significantly altered by user through hardware enhancements modifications and or test or application software Thus with respect to Council Directive 89 336 EEC Directive on compliance with the EMC protection requirements this equipment has no autonomous function Consequently this equipment is not marked by the CE symbol EEDT ST 0005 10 Redemption of Waste Electrical and Electronic Equipment WEEE in accordance with legal regulations applicable in the European Union only This equipment including all accessories is not intended for household use After use the equipment cannot be disposed of as household waste NEC Electronics Europe GmbH offers to take back the equipment All you need to do is register at www eu necel com weee All other product brand or trade names used in this pamphlet are the trademarks or registered trademarks of their respective owners Product specifications are subject to change without notice To ensure that you have the latest product data please contact your local NEC Electronics sales office User s Manual U18028EU1V1UMEO NOTES FOR CMOS DEVI
9. O0 compiler RA78KO assembler e DF0714 78K device file 34 User s Manual U18028EU1V1UMEO
10. anual U18028EU1V1UMEO 29 30 Chapter 4 Design Figure 4 3 Main MAIN E Initialization Enable over current interrupt Disabling carrier synchronous interrupt Disabling inverter timer operation Disabling real time output operation Stopping timer for measuring 20 ms Check specified speed E Clear watchdog timer 1 Changing system status from operation to stop Read switch pattern port No Operating Pressed key Pressed key START STOP a START STOP 0 FORW ARD Q REVERSE Q T User s Manual U18028EU1V1UMEO Chapter 4 Design Figure 4 4 Changing Revolution Direction No No Revolving CCW Revolving CW Yes Yes Change revolution to CW direction Change revolution to CCW direction Read value of Hall IC Change the system status from stop to operation Enable carrier synchronous interrupt Value of Hall IC Enable inverter timer operation is abnormal Enable real time output port operation Start timer for measuring 20 ms Read value of Hall IC Set default value of PWM Display HALL on LED Wait for RESET by HALT instruction No 20 ms passed Clear interrupt request flag CMIF10 Calculated manipulated variable from difference MVn MVn 1 Kp en en 1 Ki en Kd en en 1 1 en 2 Change duty factor of PWM adding MVn User s Manual U18028EU1V1UMEO 31 Chapter 4 Design Figure 4 5 Checking Specified Speed Check specifie
11. ator coils Turning on and off the switching elements with a pulse width modulation PWM signal during the 120 degree excitation period can control the amplitude of the voltage The chopping effect on the phase voltage controls the current through the coils and the torque developed in the rotor 2 6 2 PID control To maintain a constant revolution speed a proportional integral derivative PID controller is use The controller compares the speed measured by the Hall sensors with a set speed and adjusts the duty factor of the PWM signal accordingly User s Manual U18028EU1V1UMEO 21 MEMO 22 User s Manual U18028EU1V1UMEO 3 1 Configuration Chapter 3 System Overview Figure 3 1 System Configuration External DC Power Motor Control Board Low Voltage M 78F0714 Power Module CPU Board BLDOM with Hall Sensors Note Only the communication commands are described in this document The system consists of a motor drive module containing the power switching transistors a motor control board equipped with operator interface elements to control the motor and the M 78F0714 CPU board User s Manual U18028EU1V1UMEO 23 Chapter 3 System Overview The BLDCM is a three phase four rotor pole two poles facing each other motor with Hall sensors mounted at 60 degree intervals between the stator coils This configuration detects the rotor position changes at every 60 electrical degrees and every 30 physical degre
12. d speed Read specified speed A D conversion Convert carrier synchronous interrupt interval to detectable number of revolutions Specified speed is different from the previous value Display specified speed on LED Set number of times of display for operation RETURN Figure 4 6 Synchronous Carrier Interrupt Carrier synchronous interrupt Number of times of displaying specified speed is 0 No Yes Display actual speed Increment number of times of display Increment number of times of reading No Value of Hall IC changes Number of times of interrupt is 300 or more Calculate actual speed from number of times of interrupt Clear number of times of interrupt to O Set excitation pattern to real time output RETURN Stop inverter timer Stop real time output Display on LED Wait for RESET by HALT instruction 32 Users Manual U18028EU1V1UMEO Chapter 4 Design Figure 4 7 Over current Interrupt Over current Interrupt Stop inverter timer Stop real time output port Display 0 C on LED Wait for RESET by HALT inctruction User s Manual U18028EU1V1UMEO 33 Chapter 5 Development Environment 5 1 Hardware Low voltage starter kit MC LVKIT 714 MC CPU 78F0714 micro board MCI O user interface board MC LV INVERTER low voltage power module BLDCM PITTMAN N2311 motor 5 2 Software PM plus environment platform e CC78K
13. eed DISP1 to 4 Displaying speed rpm Notes 1 The target speed is always displayed while the motor is stopped om RON The actual motor speed is displayed while the motor is revolving To display target speed while the motor is running press MODE button If PC is displayed the motor can be controlled through a PC GUI In PC mode only the RESET function can be used Table 3 2 lists the uPD78F0714 MCU pins used for interfacing with the motor drive Table 3 2 Pin Interface Functions Pin Number Pin Name Function 8 RESET RESET SW1 1 27 to 32 TWOTOO to 5 3 phase PWM inverter selection 11 PO1 INTP1 Hall IC signal U phase 10 PO2 INTP2 Hall IC signal V phase 9 PO3 INTP3 Hall IC signal W phase 20 P53 INTP5 Revolution speed measurement 49 to 52 P64 to P67 8 segment LED selection LD LEDO to 3 56 P73 START STOP SW2 55 P72 FORWARD SW3 54 P71 REVERSE SW4 53 P70 MODE SW5 41 to 48 P40 to P47 Output data to 8 segment LED 12 TWOTOFFP INTPO Over current detection 5V 0V 60 ANI4 Speed change R52 33 P10 Communication via RS 232C CTS 34 P11 Communication via RS 232C RTS 36 P13 RXDOO Communication via RS 232C RXD 37 14 00 Communication via RS 232C TXD Note Pins 1 and 2 of 2JP7 are short circuited User s Manual U18028EU1V1UMEO 25 Chapter 3 System Overview In PC mode the commands listed in Table 1 3 can be executed
14. es Figure 3 2 Block Configuration of the Universal Platform LV Power Module Inverter Control Signals TU gt lt 1 Overcurrent Detection Signal Analog 8888 8 Segment LED The motor can be controlled with the push buttons on the motor control I O board or with the PC GUI through the RS 232C port Motor speed or operation mode is displayed on the 8 segment LED The same information can also be displayed in the PC GUI 3 2 Operational Controls The system described here has the following operational controls 24 RESET switch to reboot the system reboot START STOP switch to start and stop motor revolution FORWARD and REVERSE switches to change revolution direction MODE switch to change control mode SPEED potentiometer to change revolution speed Revolutions per minute rpm display Automatic emergency shutdown function in case of a motor over current detection Commands to control the system from the computer RS 232C User s Manual U18028EU1V1UMEO 3 3 User Interface Chapter 3 System Overview The user interfaces hardware and functions are listed in Table 3 1 Parts Number SW1 Table 3 1 RESET Function Name User Interface Function Reset SW2 START STOP Start stop SW3 FORWARD Revolution direction CW SW4 REVERSE Revolution direction CCW SW5 MODE Changing control mode R52 SPEED Changing target sp
15. fic The Specific quality grade applies only to NEC Electronics products developed based on a customer designated quality assurance program for a specific application The recommended applications of an NEC Electronics product depend on its quality grade as indicated below Customers must check the quality grade of each NEC Electronics product before using it in a particular application Standard Computers office equipment communications equipment test and measurement equipment audio and visual equipment home electronic appliances machine tools personal electronic equipment and industrial robots Special Transportation equipment automobiles trains ships etc traffic control systems anti disaster Systems anti crime systems safety equipment and medical equipment not specifically designed for life support Specific Aircraft aerospace equipment submersible repeaters nuclear reactor control systems life support systems and medical equipment for life support etc The quality grade of NEC Electronics products is Standard unless otherwise expressly specified in NEC Electronics data sheets or data books etc If customers wish to use NEC Electronics products in applications not intended by NEC Electronics they must contact an NEC Electronics sales representative in advance to determine NEC Electronics willingness to support a given application Note 1 NEC Electronics as used in this statement means NEC
16. g EA Initializes peripheral I O Initialization Unmasks overcurrent interrupt Clears watchdog timer Checks specified speed speed display Reads switch pattern Starts motor if START STOP switch is pressed while motor is stopped Stops motor if START STOP switch is pressed while motor is revolving Changes revolution to clockwise if FORWARD command is received while motor is revolving Changes revolution to counterclockwise if REVERSE command is received while motor is revolving Calculates actual speed Performs PID control every 20 ms while motor is revolving Executes A D conversion of specified speed voltage Converts read value 0 to 1023 to speed measurable at interval time of carrier Check specified speed synchronous interrupt Displays converted speed on LED U phase Hall IC interrupt Retains timer value Carrier synchronous Reads the pattern of Hall sensors interrupt Sets the excitation pattern corresponding to Hall pattern Stops 10 bit inverter control timer and 16 bit timer event counter 00 Overcurrent interrupt Displays characters 0 on the LED Stops processing when HALT instruction is executed 4 4 Processing Flow The flow of processing of each module is illustrated below Figure 4 2 Initialization Initialization Initialise ports Initialise timers Initialise clock Setup watchdog timer Initialise AD RETURN User s M
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18. ified speed Overcurrent interrupt A D converter ANI4 Interrupt function INTPO Speed measurement Communication with PC U phase Hall IC interrupt INTP5 8 bit timer event counter 00 TMOO 12 8 us Serial interface UARTOO Fail safe reset 26 Watchdog timer User s Manual U18028EU1V1UMEO Chapter 4 Design 4 1 Motor Speed With a 3 phase 4 pole BLDCM the value of the U phase Hall sensor IC changes 4 times per motor revolution The speed is calculated using a timer tick of 12 8 us with the equation N 60 s n 4 where number of revolutions per minute rpm e 5 timer ticks 12 8 us N timer value This system supports a speed range of 300 rpm to 3000 rpm 4 2 PID Operation To maintain a constant motor speed regardless of the load the reference speed set by the potentiome ter on the board is compared with the actual speed measured with the Hall sensors and PID control operation is performed on the resulting speed error signal The result of the PID algorithm con trols the duty factor voltage of the PWM signals to reduce the speed error to zero The PWM signal s duty factor is calculated based on the following speed type PID algorithm suitable for the sampling method used discrete value These values were manipulated scaled to be able to use them as 16 bit integers MVn 1 AMVn Kp en en 1 Ki en Kd en en 1 en 1 en 2 Current manipu
19. lated variable Previous manipulated variable Difference between current and previous manipulated variables Current deviation difference between specified speed and actual speed Previous deviation Deviation before previous deviation Proportional gain constant Integral gain constant Derivative gain constant The optimum values of the gain constants depend on the motor characteristics and the presence or absence of a load In this system the values were chosen experimentally on trial by error basis and default values were verified during operation The interval of PID control is set to be longer 100 ms than the interval 50 ms at 300 rpm of updating the revolution speed User s Manual U18028EU1V1UMEO 27 Chapter 4 Design 4 3 Software Module Configuration Figure 4 1 shows status transitions of the system Figure 4 1 Status Transition of System START RESET i Standalone PC operation Interrupt Exception processing Standalone mode 4 Motor PC command PC Over current command 2 Carrier synchronous Interrupt b Phase U EN Hall Interrupt Process SPEED FORWARD REVERSE The carrier synchronous interrupt is generated every 100 us default 28 Users Manual U18028EU1V1UMEO Chapter 4 Design Table 4 1 shows the modules of the system and their main processing Table 4 1 Module and Main Processing Module Name Main Processin
20. ould be used It is recommended to avoid using insulators that easily build up static electricity Semiconductor devices must be stored and transported in an anti static container static shielding bag or conductive material All test and measurement tools including work benches and floors should be grounded The operator should be grounded using a wrist strap Semiconductor devices must not be touched with bare hands Similar precautions need to be taken for PW boards with mounted semiconductor devices STATUS BEFORE INITIALIZATION Power on does not necessarily define the initial status of a MOS device Immediately after the power source is turned ON devices with reset functions have not yet been initialized Hence power on does not guarantee output pin levels I O settings or contents of registers A device is not initialized until the reset signal is received A reset operation must be executed immediately after power on for devices with reset functions POWER ON OFF SEQUENCE In the case of a device that uses different power supplies for the internal operation and external interface as a rule switch on the external power supply after switching on the internal power supply When switching the power supply off as a rule switch off the external power supply and then the internal power supply Use of the reverse power on off sequences may result in the application of an overvoltage to the internal elements of the device causing malfunction and deg
21. radation of internal elements due to the passage of an abnormal current The correct power on off sequence must be judged separately for each device and according to related specifications governing the device INPUT OF SIGNAL DURING POWER OFF STATE Do not input signals or an l O pull up power supply while the device is not powered The current injection that results from input of such a signal or I O pull up power supply may cause malfunction and the abnormal current that passes in the device at this time may cause degradation of internal elements Input of signals during the power off state must be judged separately for each device and according to related specifications governing the device User s Manual U18028EU1V1UMEO The information in this document is current as of August 2006 The information is subject to change without notice For actual design in refer to the latest publications of NEC Electronics data sheets or data books etc for the most up to date specifications of NEC Electronics products Not all products and or types are available in every country Please check with an NEC Electronics sales representative for availability and additional information No part of this document may be copied or reproduced in any form or by any means without the prior written consent of NEC Electronics NEC Electronics assumes no responsibility for any errors that may appear in this document NEC Electronics does not assume any liability for
22. rter nana amana ana 16 120 Degree Excitation Pattern and U Phase Current Waveform 17 Excitation Patterns and Current Flux Directions 18 Attraction and Repulsion of Magnetic 19 mE O EE CREE 20 System Configuration 0000 amana nn ai aei 23 Block Configuration of the Universal 24 Status Transition of System 0 44 000 neam nana 28 IZ cT 29 a 30 Changing Revolution Direction enne nennen 31 Checking Specified Speed men nea eene nnns 32 Synchronous Carrier 1 32 Over current eene eene ennemi nennen nnns 33 User s Manual U18028EU1V1UMEO 11 12 User s Manual U18028EU1V1UMEO Table 1 1 Table 2 1 Table 3 1 Table 3 2 Table 3 3 Table 3 4 Table 4 1 List of Tables Documents Related to Motor Control Evaluation System Components 15 Relationship Between Hall ICs and Excitation 20 User Interface ee creen e E MERE 25 Pin Interface FUNCIONS G nnn 25 Communication Commands sse eene nennen enne 26 Peripheral OS e EL
23. ser s Manual U17857E Low Voltage Power Module for Motor Control Users Manual U18052bE User s Manual U18028EU1V1UMEO 15 Chapter2 Controlling a BLDCM A BLDCM revolves as a result of the interaction of its permanent magnet rotor with a magnetic field generated when a DC voltage is connected across a set of stator coils To maintain rotation the orien tation of the magnetic field in the stator has to be rotated sequentially This is accomplished by connect ing the DC voltage across the next set of stator coils as the rotor revolves To maintain synchronization with the rotating stator magnetic field the rotor position must be known at fixed angular intervals BLDCM are also known as electronically commutated EC motors and are driven by a DC to AC power inverter controlled with a dedicated MCU 2 1 Driving by Inverter The generation of the rotating magnetic field is implemented using a 6 transistor inverter bridge as shown in Figure 2 1 Figure 2 1 Six Transistor Inverter Bridge Inverter DC power supply By controlling the commutation of six switching elements the DC bus voltage can be applied across any combination of two stator coils of the BLDCM 16 User s Manual U18028EU1V1UMEO Chapter 2 Controlling a BLDCM 2 2 120 Degree Excitation Mode Figure 2 2 shows the 120 degree excitation method Figure 2 2 120 Degree Excitation Pattern and U Phase Current Waveform U Phase Current U Phase Voltage 120 180
24. the rotor position three Hall sensors are placed around the rotor perimeter at equal angular intervals For a two pole rotor the Hall sensors are placed at 120 degrees The logic state of each sen sor changes every 180 degrees but the combination pattern of the three sensors changes every 60 degree intervals If the rotor has four poles distinct positions can be detected at every 30 degrees physical angle physical angle electrical angle number of poles facing each other More commonly a BLDCM with four rotor poles has the Hall sensors spaced at 60 degree intervals so that the rotor position can be detected at 60 electrical degrees and 30 physical degrees Table 2 1shows an example of an excitation pattern change based on the Hall sensor logic states Table 2 1 Relationship Between Hall ICs and Excitation Patterns 3 2 CIN IC Hv Hi Hi Hi Lo Lo Lo Hw Lo Lo Hi Hi Hi Lo This relationship depends on the mounting positions positional relationship of the stator of each phase of the Hall sensor 20 Users Manual U18028EU1V1UMEO Chapter 2 Controlling a BLDCM 2 5 Speed Detection The revolution speed of the motor is calculated from the time interval measured between the Hall sen sor transitions A 16 bit timer counts 12 8 us time intervals between the Hall sensor transitions 2 6 Speed Control 2 6 1 Voltage control The revolution speed of the BLDCM is directly proportional to the voltage applied to the st
25. to control operation of the motor Command from PC Get product ID Table 3 3 Communication Commands Parameter None Return Value Product ID Description Gets ID of firm Get version None Version Gets firm version Reset None ACK Resets program of firm Start revolution None ACK Starts revolving motor Stop revolution None ACK Stops revolving motor Set PID gain Kp Ki Kd ACK Changes gain of PID Get PID gain None Kp Ki Kd Gets gain of PID Set target number of revolutions Number of revolu tions ACK Specifies target number of revolutions Get target number of revolutions None Target number of revolutions Gets target number of revolutions of motor Get actual number of revolutions 3 4 Peripheral I O None Actual number of revolutions Gets actual number of revolutions of motor This system uses the peripheral I O registers of the uPD74F0714 MCU Function Inverter timer Real time output Table 3 4 Peripheral I Os Peripheral I O Function Name uPD78F0714 10 bit inverter control timer default value of carrier frequency is 10 kHz symmetrical triangular wave Real time output port 16 bit timer capture compare register 01 CRO1 Feedback time Wait processing 8 bit timer event counter 51 default value 100 ms 8 bit timer event counter 50 generating 1 ms timer Reading spec
26. with Hall sensors for MC LVKIT 714 motor control evaluation system This system specification describes the following sections Controlling a BLDCM System overview Design Development environment Symbols and notation are used as follows Weight in data notation Left is high order column right is low order column Active low notation XXX pin or signal name is over scored or xxx slash before signal name Memory map address High order at high stage and low order at low stage Note Explanation of Note in the text Caution deserving extra attention Remark Supplementary explanation to the text Numeric notation Binary XXXX or Decimal XXXX Hexadecimal XXXXH or Ox Prefixes representing powers of 2 address space memory capacity kilo 21 1024 M mega 2 1024 1 048 576 giga 290 1024 1 073 741 824 User s Manual U18028EU1V1UMEO 7 User s Manual U18028EU1V1UMEO Table of Contents Preface Ex EA Var d AUR Econ 7 Chapter 1 Introduction court Eb ERR as as 15 Chapter2 Controlling a 16 21 Driving by 16 2 2 120 Degree Excitation 17 2 3 Excitation Pattern 4 xt Eel 18 2 4 Position
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