Stellaris LM3S617 Stepper Motor RDK User`s Manual (Rev. A)
Contents
1. 15V 4 VMOTOR 4 NOTES 8 01 8 Can subst FDMS3682 for lower Rds on 1 gt OMIT 5 O 1UF PH_AI cls 26 Q3 2 05 01 8 Can subst FDS3672 in SOIC package 10uF S FDMS3672 Z FDMS3672 R17 25V R23 310K AN E 100 H vs 4 il DT SDn 5 R24 T MOTOR gt 8 Lo MOTOR_A2 01 R19 9 100 A Ze Q4 4 Q6 20K S E FDMS3672 FDMS3672 aam 6 2 R29 3 i OMIT 4 R28 ET 2 5X 15V 1 3 4174155 D8 R22 n R27 2 0 1 IW a 9 OMIT PH A2 IN C19 10uF 0 1UF Bn s HO 100 vs 4 3 DT SDa 2 2 R26 2 10 ANY qi 0 6 100 ISENSEA 20K 5 TP6 B1 B2 33 T U4 S Green C20 2 4 MOTOR A2 3 N vec H 0 1UF Black 4 3 2 MOTOR ojo our POSTON i 2 1 MOTOR iunc 3 Red 43045 0409 2 MOTOR B2 mE Rotating Permanent Magnet optional 1 MOTOR NEMA23 OUTLINE 3 I TEXAS INSTRUMENTS Drawing Tite Stepper Motor Reference Design Kit 5 an Page Title Stepper Motor Connections Linear Hall Effect Position Sensor Driver Coll Size B Document Number Date 7 10 2007 OS NA 62. 2 15V 34 DT SDn 5 3 Q7 FDV31ON 100PF C26 27 25V 0 1UF 1 R32 310K VDD VS VMOTOR Q9 FDMS3672 Q11 FDMS3672 8 FDV31ON 100 MOTOR MOTOR B2 R39 AMY 100 ie 2 010 012 20K FANT3832 FDMs3672 FDMS3672 gt R44 5 5 OMIT R43 15V 4 3 10 C T R42 C33 0 1 IW INF 1 9 OMIT IN 602 10uF 2552 25 R40 10K 100 vs LS 4 3 DT SDa 8 R41 85 E 20K a 8 FAN4174ISS5X gt ISENSEB gt i TEXAS INSTRUMENTS Drawing Tite Stepper Motor Reference Design Kit Page Thio Driver Coil Size p Document Number Date 7 10 2007 Sheet as 6 6 10 80VDC POWER INPUT J Un FI FB2 VMOTOR C45 3B 8 1 4 BLM21P221SG 00 PJ 002BH SMT 6 2 41 42 261K R
3. 27 Parameter DeSCriptlons eat eite 27 Motor Running Configuration 28 Target PROSIM gaii 00000 28 Mamnun e TEE aiet EA AN 28 Target Speed aa Me on a 28 aye 28 00 29 Motor Drive Configurations Ari 1 medi die d irt tente FIBRE ER Poe a 29 Winding Besistahnce id tte E e eR e i ding dads E e Per eee ba 29 PWM Frequency iet trei een tt eter fer de ee ee eec pe de oe oed eee d 29 29 Dive CUm 30 369 1050 tee cree 30 Contool Mode 110101010101 30 c 31 Step ModE 1 2 1 1 gered adt den 31 Off Blanking 31 November 4 2009 3 33 5 2 0 ecd iiie 39 nasa
4. 25 Figure 3 4 Current Control Software 21 1 25 November 4 2009 7 November 4 2009 Stellaris amp Stepper Motor Reference Design Kit Overview Stellaris Reference Design Kits RDKs from Texas Instruments accelerate product development by providing ready to run hardware a typical motor and comprehensive documentation including hardware design files Designers without prior motor control experience can successfully implement a sophisticated motor control system using the Stepper Motor Control RDK Stepper RDK Using the RDK The recommended steps for using the RDK are Follow the Quickstart Guide included in the kit The Quickstart guide will help you get the motor up and running in minutes It also contains important safety information that should be read before using the RDK Use the RDK GUI software to evaluate and optimize motor performance The RDK GUI gives real time access to more than a dozen operating parameters Parameters and data transfer between the RDK control board and PC over a USB cable Customize and integrate the hardware and software to suit an end application This User s Manual and the Software Reference Manual are two important references for completing your project Software can be programmed in the motor control board
5. lt 5 2 13 OnBoard USEF Interfaces ioci te e e d teamed E 13 EcL ME 14 Position Mode teque A E MES 14 Graphical User Interface ntu Lp ice EUH ep Ere REEL Pp reete op eem EUR 15 7 000 1 dpa dedos 18 MEE 18 Chapter 3 Hardware 21 Block 22 22 Microcontroller Schematic Pages 1 2 22 Output Power Stage Schematic Page 3 10 0000 eene 23 Control Interfaces Schematic 2 24 Sonic M DNE EL 24 ome 24 Parameter Reference uo e 1 AS ae Re 1 1 1 cete pred aee uae c cad qued a 26 Serial Protocol am aet ERAN RUBUS et me IR aUe 26 Appendix Parameters eno uuo Lu Du
6. Appendix Component Locations 41 Appendix D of Materials 4 November 4 2009 Stellaris amp Stepper Motor RDK User s Manual List of Tables Table 1 1 Table 2 1 Table 2 2 Table 3 1 Table A 1 Motor Specifications sira o erkennt e Wee due da 11 Description of GUI Main Window Controls 16 Description of Configuration 19 Gurrent Monitoring CirCuits 10101 23 Parameter Configuration 27 November 4 2009 5 November 4 2009 Stellaris amp Stepper Motor RDK User s Manual List of Figures Figure 1 1 Stepper Motori teint 0000 10 Figure 1 2 Stepper Speed Torque 11 Figure 2 1 On board User 13 Figure 2 2 Stepper Main GUI 15 Figure 2 3 Configuration Window 19 Figure 3 1 Stepper Motor Control 21 Figure 3 2 51661015418411 ed 22 Figure 3 3 Chopper Waveform Generation
7. The RDK has a 20 pin ARM JTAG port for programming and debugging A standard debug interface can be connected to this header J1 Unallocated GPIO signals from the microcontroller are routed to pads labeled P1 P19 Several peripheral blocks are available for external use including SPI and UART1 The I O pads are on a 0 1 grid to allow standard headers to be installed 22 November 4 2009 Stellaris amp Stepper Motor RDK User s Manual Also on this page are several LED status indicators a simple reset circuit and on board user interface The speed position potentiometer s value is read by the microcontroller s ADC Because the ADC s input span is 0 3 V a resistor R14 is used to pad the potentiometer voltage The microcontroller s on chip analog comparator provides an over current trip function Diodes D2 and D3 gate the greater of the two motor coil currents into an R C network which connects to the inverting comparator input Inside the microcontroller this level is compared to a programmable voltage reference An interrupt will be generated in the event of an over current condition allowing the software to quickly shut down the power stage Output Power Stage Schematic Page 3 The power stages on schematic pages 3 and 4 are identical One power stage is used for each of the two coils in the bipolar stepper motor The power stage consists primarily of a MOSFET H bridge and associated gate drivers The H bridge allows the microco
8. Caution Do not leave the motor running for long periods of time If the motor is not attached to a heat sink the case can get very hot especially if a high drive current is used Position Mode Upon entering Position mode the mode LED blinks twice To enter Position mode from Speed mode press and hold the user button for five seconds until the mode LED blinks two times In Position mode the motor always runs to a position that is determined by the position of the potentiometer When the potentiometer is moved the motor moves to the new position The input from the potentiometer is scaled so that the motor turns one revolution at 200 steps revolution as the knob is turned from one extreme to the other The motor turns in the same direction as the potentiometer knob In Position mode the motor is enabled by default and turns as soon as the knob is turned If the button is pressed then the motor is disabled and does not run when the knob is turned The motor can be re enabled by pressing the user button again 14 November 4 2009 Stellaris amp Stepper Motor RDK User s Manual Graphical User Interface The stepper motor RDK board can be controlled from a graphical user interface GUI program running on a PC Using the GUI provides much greater control of the motor than the on board interface Use the GUI to set specific values for position speed acceleration and deceleration as well as a number of other parameters to tune the
9. 5 C6 C10 33 SPEED CTRL 38 Abc e ADCS y RI osco osco 5100 47K OSCI RESETn swi _ GND cl GND SW PB 1UF 6 00MHz GND 9 e 18PF 18PF LM3S6 ISENSEA ISENSEB ISENSEAB gt 0 010 0 1UF 0010 0 1UF 0 010 33 3 R5 10K ACCES P PCS CCPT Q GND samo os 333V GND o PCO CCP3 9 9 PAJ SSICIK 3 PA3 SSIFSs IO PA4 SSIRX Pii PAS SSITx 5 PB CO 2 5 2 vid PD2 UIRx 2 E PD3 UITx 9 E GND 15V Expansion Header Connect Optional Limit Switches to 21 2 and 23 4 SWUSR LEDSTATUS LEDMODE 3 3 SPEED CTRL Mode Push Button sw2 SW PB 220 Status LED D4 Green R12 1 220 Mode LED D5 Green Power LED Speed Position Control Pot R13 10K RESETn TDO TCK SWCLK TMS SWDIO TDI 2X10 HEADER JTAG SWD JTAG SWD Debugger Header i Texas INSTRUMENTS Drawing Tite Stepper Motor Reference Design Page Title Microcontroller Size p Document Number Date Sheet 2 7 10 2007 of 5 2 6
10. 000 The Stepper RDK operates bipolar stepper motors with two coils probably the most common class of stepper motor Bipolar refers to the fact that the stepping sequence requires coil current to flow in alternating directions By comparison unipolar motors require current in only one direction and are simpler to drive but have much lower torque for the same frame size Stepper motors are designed for accurate open loop positioning and not for high efficiency As a result stepper motors operate at high temperatures Current to the motor should be adjusted so that the motor case temperature never exceeds 100 C Chopper Control A stepper motor can be operated at its rated DC voltage but only low step rates are possible This is because the current builds comparatively slowly in the stator coil To overcome this chopper control uses a supply voltage much higher than the motor s rating This allows the coil current to increase rapidly to the desired level before the control starts modulating or chopping the voltage to maintain that level This allows higher step rates with more torque A supply of 5 20 times the motor s DC voltage is commonly used Table 1 1 RDK Motor Specifications Holding Torque 166 2 1 29 Nm Rated Current 2 8 A phase Coil Resistance 0 750 Step Angle 1 8 November 4 2009 11 Stellaris amp Stepper Motor Reference Design Overview RDK Specifications This reference design
11. Figure 3 4 This technique could be applied to other loads that benefit from a constant current control Figure 3 4 Current Control Software Flow ADC Interrupt ISR Timer Interrupt ISR Read ADC Sample Turn control pin ON Start new Start ADC acquisition acquisition Turn control pin Exit ISR OFF Start OFF blanking timer Exit ISR November 4 2009 25 Hardware Description In addition to eliminating a dedicated chopper control IC software based chopper control makes it possible to easily change the current set point As an example the RDK GUI has several parameters that change chopper control behavior for motors and loads that have differing characteristics Parameter Reference See Appendix A Parameters on page 27 for a detailed description of the RDK s parameters Serial Protocol See the Stepper Motor Control RDK Software Reference Manual for more information 26 November 4 2009 j Parameters Table A 1 provides a summary of all configuration parameters See Parameter Descriptions on page 27 for more information Table A 1 Parameter Configuration Summary Motor Running Configuration Parameters Target Position PARAM_TARGET_POS whole 8388608 8388607 0 28 steps Maximum Current PARAM MAX CURRENT mA 1000 10000 4000 28 Target Speed PARAM TARGE
12. Resolution 137 5 mV 1 375 A 10 bits Scale 100 mV A 0 15 V 1 bit 2 2 67 mA A Programmable In software Trip Threshold typ Trip Speed 4 10 us Software dependent Page 3 also shows a linear hall effect sensor for positional feedback This circuit is not presently populated November 4 2009 23 Hardware Description Control Interfaces Schematic Page 4 The Stepper RDK has three power supply rails The input power source is used directly to provide motor power and has a wide operating range The exact supply voltage is not critical because the chopper control maintains constant motor current Unregulated supplies can be used successfully The microcontroller can monitor the input voltage level using a simple Vsense circuit however this measurement is not needed for the chopper control algorithm A simple step down switching regulator directly generates 3 3 V for the microcontroller The 15 V gate driver power supply comes from a second stage boost converter in this case a FAN5331 device from Fairchild semiconductor Finally a FT232RL device provides a USB virtual COM port The virtual COM port is a fast and reliable method of communication between the motor control board and the RDK GUI software The protocol description can be found in the Software Reference Manual and could be used as a general purpose control method from other hosts Software The Stepper Motor Control RDK software manages four
13. Revision Date Description U_Stepper Ph B Drive Stepper Ph Drive SchDoc U_Stepper Power Supplies Stepper Power Supplies SchDoc 0 Jan 17 07 First Full Release 0 1 Feb 07 07 Change USB device to bus power A A 1 Feb 09 07 Jul 10 07 First Production Revision Change C18 C19 C31 C32 to no populate i Texas INSTRUMENTS Drawing Tite Stepper Motor Reference Design Kit Page Title Contents Page Size p Document Number Date Sheet 7 10 2007 of 5 A 2 6 6 Reset TP FAULT Ul VCP RX ver Wm PA3 SSE PA3 SSIFss E 7 PA4 SSIRX he PAS SSIT TU NDS 4 PCO TCK SWCLK pe PCUTMS SWDIO PCNIDO SWO PCA CCPS iH PCA CCPS 5 1 13 Sr 5 PC6 CCP3 ni PC7 CCP4 ADCO ADCI ADC2 ADC3 PBO PWM2 PBI PWM3 PB2 PB3 FAULT PB4 CO 5 0 6 0 PB7 TRST PH 2 SWUSR ISENSEAB R6 PB6 CO 10K PB7 nTRST PDO PWMO PDI PWMI PD2 UIRx PD3 UITx PDS CCP2 LEDSTATUS LEDMODE a PEQ PWM4 2 PH_A_ENn gt PELPWMS 9 PH_B_ENn gt 6 LDO
14. motor when Speed mode is used and is used to adjust the position of the motor when Position mode is used Mode LED Informs the user which mode is selected by blinking a pattern Status LED Indicates the motor speed by blink rate Also indicates a fault with rapid blinking Speed Mode Upon entering Speed mode the mode LED blinks one time This is the default when the board is first powered or after the reset button is pressed To enter Speed mode from Position mode press and hold the user button for five seconds until the mode LED blinks one time In Speed mode the motor runs at a speed that is controlled by the position of the potentiometer knob Upon entering Speed mode the motor is stopped To start the motor running press the user button The motor begins running in the forward direction Forward is designated as clockwise Use the user button to start and stop the motor Each time the button is pressed the motor either starts running if it is stopped or stops if it is already running Each time the motor starts running it runs in the opposite direction from the previous time The potentiometer knob is used to change the motor speed The motor runs at a minimum speed of 10 steps second when the knob is turned all the way to the left counterclockwise and at a maximum of about 1000 steps second when the knob is turned all the way to the right clockwise The status LED blinks at a rate that varies according to the motor speed
15. number and status If the indicator is shown in black and displays a number for the COM port then the serial port is opened If the indicator is shown in red and displays Err then no COM port is opened The COM port selection dialog box can be opened by double clicking on the COM port indicator Target Displays the status of the target connection If the Target is shown in black and indicates Stepper then the program is communicating with the RDK via the USB serial port If the indicator is shown in red then there was a problem communicating with the target Communication with the target can be restarted by double clicking on the Target indicator Fault Indicates that an overcurrent fault has occurred Otherwise the control is not visible To clear the fault condition double click on the Fault indicator November 4 2009 17 User Interfaces File Menu The File menu can be used to help manage the parameters The following menu items are available Load Parameters from Flash The adjustable parameters that control the motor operation may be stored in flash memory in the RDK microcontroller This menu choice commands the target to copy the parameters that were found in flash into the active memory The parameters are only loaded from flash if the motor is not running If the parameters are loaded from flash then the values shown on the main and configuration windows change to reflect the new parameter values Save P
16. operation of the motor The GUI program communicates with the RDK board using a virtual serial port over a USB cable Upon starting the GUI program the on board interface on the RDK board is disabled and the knob and button have no effect If the program has not been used before then a dialog box appears that lets the user select the COM port to use Once a COM port is selected the program remembers the selection and does not ask again However at any time the user can re open the COM port dialog box by double clicking on the COM port indicator on the main panel The stepper motor operation is controlled from the main window see Figure 2 2 The main window provides user controls for controlling the motor as well as several indicators to provide status of the motor operation Most parameters can only be modified when the motor is stopped and are not selectable while the motor is running Table 2 1 describes the controls in detail Figure 2 2 Stepper Main GUI Window 5 Stepper Motor Drive File Help Speed Speed steps sec O Target E 500 Actual 56 Status DECEL Drive Current m 3 1500 2 Accel steps sec 2 310 Decel steps sec 2 10 0 50000 40000 30000 20000 10000 10000 20000 30000 40000 50000 Position Statistics DC Bus Voltage 233 Configure Motor Current 21A Actual
17. 2W 2512 Omron 1 35617 25 Microcontroller ARM Cortex 48 Fairchild FTDI Imagineering SureStep Wall Adapter 24Vdc 15W with interchangeable Phihong plug adapters Kit of 4 plugs USA EU UK Aust Phihong Rubber Feet Black 43 44 November 4 2009 IMPORTANT NOTICE Texas Instruments Incorporated and its subsidiaries reserve the right to make corrections modifications enhancements improvements and other changes to its products and services at any time and to discontinue any product or service without notice Customers should obtain the latest relevant information before placing orders and should verify that such information is current and complete All products are sold subject to Tl s terms and conditions of sale supplied at the time of order acknowledgment TI warrants performance of its hardware products to the specifications applicable at the time of sale in accordance with TI s standard warranty Testing and other quality control techniques are used to the extent TI deems necessary to support this warranty Except where mandated by government requirements testing of all parameters of each product is not necessarily performed TI assumes no liability for applications assistance or customer product design Customers are responsible for their products and applications using Tl components To minimize the risks associated with customer products and applications customers should provide ad
18. 4610 Processor Usage 10 Temperature 25C 8 COM4 Target 5 4i 5 INSTRUMENTS November 4 2009 15 User Interfaces Table 2 1 Description of GUI Main Window Controls 16 1 Speed and Status Area Target Sets the motor running speed in steps per second The desired speed can be typed into the box If the motor is already running it changes speed to match Actual Indicates the actual motor running speed in steps per second This value is calculated in the RDK firmware it is not actually an independent measurement of motor speed Status Indicates if the motor is stopped running accelerating or decelerating Drive Settings Area Drive Current Sets the value of the current that the motor control function should try to maintain in the motor winding when the winding is on during the step sequence Accel Sets the rate at which the motor accelerates to the running speed in steps second The desired acceleration can be typed into the box The new value is used the next time the motor needs to accelerate Decel Sets the rate at which the motor decelerates from speed to stopped in steps second The desired deceleration can be typed into the box The new value is used the next time the motor needs to decelerate Position Area Target Sets the position of the motor in steps The mo
19. Controls Continued GUI Main Window Buttons Run button Enables the stepper motor for running The stepper motor must be enabled before it can be used The motor does not move immediately when the Run button is pressed It only moves after the position control is used to set a new position Stop button Stops the motor If the motor is running the motor decelerates to a stop Once the Stop button has been clicked the Run button must be clicked before the motor will operate again Configure button Opens the Configuration window The Configuration window is described in more detail in Configuration Window on page 18 Statistics Area DC Bus Voltage Shows the voltage supplied to the motor as measured by the microcontroller Motor Current Shows the peak current of the two windings averaged together This value is sampled when the windings are switched on The current during the time when the windings are switched off is not measured and that is not reflected in the measurement The motor current is not available if PWM mode is used and the current indicator will be grayed out Processor Usage Indicates the microcontroller CPU load by percentage Useful for estimating the loading of different applications and motor control algorithms Temperature Indicates the internal temperature sensor of the microcontroller Special Indicator Area COM Port Displays the COM port
20. ONISD Ber C44 S100 TP2 VSENSE T 18008 TOUP GND R52 3 FB3 2 4 RCL 100K BLM21P221SG 4 RIN 5008 3 3V 300mA Switching Regulator J4 USB MINI B RECEPTACLE 15 FN NN NEY 4 OMIT DR73 100R 10uH S100 C49 100pF C50 09 FT232RL 10uF 25V 0 1UF I gt RXD VCP TX SENG USBDM RTSn USBDP CTSn FANS331 47K DTRn s DSRn z NC DCDn 3 RESET 1 15V 30mA Power Supply for Gate Drive 2 e 211 CBUSO 1 CBUSI CBUS2 CBUS 69204 CBUS4 gt 0 0 0 USB Virtual Port Texas INSTRUMENTS 13 Drawing Tite Stepper Motor Reference Design Kit Done o Power Supplies and USB Size p Document Number Date 7 10 2007 Bret pr P 6 Component Locations This section shows the PCB component locations for the Stepper Motor RDK November 4 2009 39 8531 R30 US arme 23 R29 TP1 21 R28 R27 TP2 R45 R46 C35 R44 R43 C33 R42 U8 Swi 011 49 TP7 P13 P14 C38 R50 2 5 P19 pig 17 C9 C10 C5 c2 03 5 e P6 P5 P4 P3 P2 P1 9 2 9 10 Bill of Materials This section provides the BOM for the Stepper Motor RDK November 4 2009 41 42 Texas I nstruments Edison Project Stepper Motor Reference Design Ki
21. Stellaris Stepper Motor Reference Design Kit User s Manual Xi TEXAS INSTRUMENTS RDK Stepper 03 Copyright 2007 2009 Texas Instruments Copyright Copyright O 2007 2009 Texas Instruments Inc All rights reserved Stellaris and StellarisWare are registered trademarks of Texas Instruments ARM and Thumb are registered trademarks and Cortex is a trademark of ARM Limited Other names and brands may be claimed as the property of others Texas Instruments 108 Wild Basin Suite 350 E Austin TX 78746 TEXAS Main 1 512 279 8800 Fax 1 512 279 8879 INSTRUMENTS http www luminarymicro com m m ortex gt Intelligent Processors by ARM ARM 2 November 4 2009 Stellaris amp Stepper Motor RDK User s Manual Table of Contents Chapter 1 Stellaris amp Stepper Motor Reference Design Kit OvervieW 22 2 2 2 9 Using the EA epi ot ere eese deer apes 9 Features 1 1 1 1 1 1 1 1 1 1 1 1 2 1 1 Gea 12121 1 1 1 1 0000 9 Motor 156115611 EE 10 Introduction to Stepper 015 0 00 6 10 Chopper 0 1 ettet ie De pot pter dn t t ricette edes Lue 11 SpecifiCallOliSc ennt eec ef dese te dio LORD LE LUE 12 Electrical 1 12 eR de oes do 12 Chapter 2
22. T SPEED steps sec 10 10000 200 28 Acceleration PARAM ACCEL steps sec 100 60000 30000 28 Deceleration PARAM DECEL steps sec 100 60000 60000 29 Motor Drive Configuration Parameters Winding Resistance PARAM RESISTANCE 100 5000 750 29 PWM Frequency PARAM PWM FREQUENCY Hz 16000 32000 20000 page 29 Fixed Rise Time PARAM_FIXED_ON_TIME uS 1 10000 800 page 29 Drive Current PARAM_DRIVE_CURRENT mA 100 3000 1500 30 Holding Current PARAM HOLDING CURRENT mA 0 3000 0 page 30 Control Mode PARAM CONTROL MODE choice Chopper Chopper page 30 Open loop or Closed loop PWM Decay Mode PARAM DECAY MODE choice Fast or Slow Slow page 31 Step Mode PARAM STEP MODE choice Full Half Micro or Half page 31 Wave Off Blanking Time PARAM BLANK OFF uS 20 10000 100 page 31 Parameter Descriptions This section describes parameter configuration in detail The parameters are grouped into two areas Motor Running Configuration parameters and Motor Drive Configuration parameters November 4 2009 27 Motor Running Configuration Target Position PARAM TARGET POS whole steps 8388608 8388607 0 This parameter indicates the target position which is represented internally as a signed 24 bit number It starts at position 0 and can run to the positive maximum or negative minimum of the range Maximum Current PARAM MAX CURRENT mA 1000 10000 4000 This parameter sets the trip point for hardw
23. Trimpot 16mm thumbwheel style SMT 50K Panasonic R35 R21 R22 R36 Resistor 33 Ohms 5 0805 R37 29 R23 R24 R25 Resistor 100 Ohms 5 0805 Generic R26 R38 R39 R40 R41 R3 R49 R51 Resistor 261K 1 0805 R31 R46 52 100 5 0805 32 R7 1 Resistor 13 3K 1 0805 November 4 2009 33 886 1 34 R53 1 35 R55 3 3 2 2 1835 1000 33 34 35 27 2 SW1 2 ao 1 41 U2 U3 U6 U7 1 1 6 7 1 U5 08 2 Non PCB Items 4 9 1 1 1 SRDK A 50 3825 TP MTR 23055 1 RPBAG R 4 November 4 2009 FAN41741S5X_NL FT232RL FOXSDLF 060 20 SJ 5018 BLACK Stellaris Stepper Motor RDK User s Manual Switch Momentary Tact SMT LM5008MM IC Integrated Step down converter FAN5331S Boost Converter SOT23 5 Fairchild FAN73832M High Low Side Gate Driver SO 8 Fairchild 1 1 1 EEE 4 A1301KLHLT T IC Linear Hall Effect sensor SOT 23 OMIT Allegro 150 IC Low Power Rail to Rail Output 3MHz Op Amp SOT 23 USB UART Asynchronous Serial Data Transfer Chip SSOP28 Pb free Crystal 6 00MHz HC49US SMT 4 4 52 x 2 80 2 layer Gloss black solder mask Knob Aluminum 1 50x0 63 for 1 4 shaft Stepper Motor NEMA23 1660z in with 12 cable Resistor 150K 196 0805 Resistor 340 Ohms 196 0805 Resistor Zero Ohm 596 0805 LR2512 LF R100 F Resistor 0 1 Ohms
24. arameters to Flash Saves the adjustable motor parameters to the RDK microcontroller s flash memory The parameters are only saved when the motor is not running If a valid set of parameters have been saved to flash those are loaded whenever the target is powered or reset Load Parameters from File The adjustable motor parameters can be loaded from a file that was previously saved This menu choice reads the parameters from the file if available and sends them to the target The parameters are only be loaded if the motor is stopped Save Parameters to File The adjustable motor parameters can be saved to a file Selecting this menu choice causes all of the parameters to be read from the RDK board and stored to a file The parameters can only be stored to a file if the motor is not running Update Firmware This menu choice can be used to load new firmware onto the RDK target board A file chooser dialog box opens to allow the user to select the firmware binary file to load to the target This menu choice can only be used if the motor is not running Once file is chosen the new firmware file is sent to the RDK the RDK updates the flash with the new program and then restarts NOTE To restore the default parameters that came with your kit from the File menu select Load Parameters from File and load the nema23 default ini parameter file to the target Then select Save Parameters to Flash from the File menu to save the default parameters in
25. are comparator If the current exceeds this value the comparator triggers a fault and places the motor in a safe configuration Target Speed PARAM TARGET SPEED steps sec 10 10000 200 This parameter sets the target speed of the motor When moving the motor accelerates up to this speed and remains at this speed until near the target position at which time it decelerates to a stop This value is in whole steps so if Half Stepping mode is used then the actual stepping rate applied to the motor will be twice this value It may be difficult to get the stepper motor up to maximum speed if it does not have a load Acceleration 28 PARAM ACCEL steps sec 100 60000 30000 This parameter is the rate at which the motor accelerates to reach the target speed Larger values work better if the motor has no load avoiding the resonant frequencies If the motor has much load then this value may need to be lowered November 4 2009 Stellaris amp Stepper Motor RDK User s Manual Deceleration PARAM DECEL steps sec 100 60000 60000 This parameter is the rate at which the motor decelerates from the target speed to stop at the target position Typically the motor can decelerate faster than accelerate since the load and friction are working to help decelerate the motor Motor Drive Configuration Winding Resistance PARAM RESISTANCE 100 5000 750 This parameter sets the resistance of the winding It should be o
26. btained from the motor specification This value is used in calculating the correct duty cycle if PWM mode is used PWM Frequency PARAM PWM FREQUENCY Hz 16000 32000 20000 If PWM mode is used this parameter determines the PWM period Fixed Rise Time PARAM FIXED ON TIME uS 1 10000 800 If PWM mode is used this parameter sets the amount of time at the beginning of a step that the winding is left with full voltage applied before PWM is used to control the current By leaving the full voltage applied to the winding the current rises as fast as possible allowing it to reach the drive current faster Caution If making adjustments to this value do not exceed the motor s rated current Use lab equipment to measure the current in the winding when making adjustments to this value November 4 2009 29 Drive Current PARAM DRIVE CURRENT mA 100 3000 1500 This parameter sets the current level in the winding when the motor is running If the Chopper mode is used then the chopper switches the voltage to the winding off and on in order to maintain this current level If the PWM mode is used then the duty cycle is calculated to maintain this current level This value should not necessarily be set to the rated current of the winding For an unloaded motor the best current setting varies with motor speed with less current needed for running at lower speeds Caution If the motor is run for long periods of time w
27. d for a duration at the start of a step This is controlled by the Fixed Rise Time parameter When using Open loop PWM mode current monitoring is not available November 4 2009 Stellaris amp Stepper Motor RDK User s Manual Closed loop PWM mode combines the features of Chopper and Open loop PWM modes Closed loop PWM mode uses a programmed PWM duty cycle to set the current However the current is also measured each time a PWM pulse is applied and the duty cycle is adjusted to compensate for variation in the measured current compared to desired drive current Decay Mode PARAM DECAY MODE choice Fast or Slow Slow This parameter specifies Fast Decay mode or Slow Decay mode In Slow Decay mode the H bridge low side switches are closed to remove voltage from the winding This allows current to circulate in the winding and decay slowly In Fast Decay mode all the switches are opened to remove voltage from the winding and the current decays rapidly For the unloaded motor slow decay seems to work best Step Mode PARAM STEP MODE choice Full Half Micro Half or Wave This parameter specifies the stepping mode In Full Step mode full positive or negative current is applied to the windings at each point in the four step stepping cycle In Half Step mode the winding current is full negative positive or 0 at each point in an eight half step stepping sequence In Micro Step mode the current in each winding is varied sinus
28. equate design and operating safeguards TI does not warrant or represent that any license either express or implied is granted under any TI patent right copyright mask work right or other TI intellectual property right relating to any combination machine or process in which TI products or services are used Information published by TI regarding third party products or services does not constitute a license from TI to use such products or services or a warranty or endorsement thereof Use of such information may require a license from a third party under the patents or other intellectual property of the third party or a license from TI under the patents or other intellectual property of TI Reproduction of TI information in TI data books or data sheets is permissible only if reproduction is without alteration and is accompanied by all associated warranties conditions limitations and notices Reproduction of this information with alteration is an unfair and deceptive business practice is not responsible or liable for such altered documentation Information of third parties may be subject to additional restrictions Resale of TI products or services with statements different from or beyond the parameters stated by TI for that product or service voids all express and any implied warranties for the associated product or service and is an unfair and deceptive business practice is not responsible or liable for any such statements TI
29. he voltage to the winding on and off in order to keep the current at the desired value Closed loop PWM In Closed loop PWM control mode the firmware sets the PWM duty cycle based on the measurement of the current flowing in the winding If the current is below the desired setting then the PWM duty cycle will be set to a large value and is reduced as the measured current approaches the desired value November 4 2009 19 User Interfaces Table 2 2 Description of Configuration Controls Continued 1 cont Fixed Rise Time This value is used when Open loop PWM control mode is chosen This value controls the amount of time that the winding is left turned on at the beginning of a step before PWM is used to control the current in the winding This allows the current in the winding to rapidly rise at the beginning of the step This value is specified in microseconds It should be adjusted with care because if the amount of time is too long then the current in the winding may exceed the rating for the motor PWM Frequency This is the frequency used for PWM when Open loop or Closed loop PWM control mode is chosen Chopper Off Blanking Time This value is used to control how long the chopper leaves the voltage off after it turns off the winding when the drive current threshold is reached At the end of the blanking time the winding is turned on again and the chopper resumes measuring the winding curren
30. ith currents approaching the rated current for the winding the motor can become very hot Use caution around the motor if a heat sink is not being used Holding Current PARAM HOLDING CURRENT mA 0 3000 0 This parameter sets the current in the winding when the motor is not running By applying current to the winding when the motor is stopped the holding torque of the motor can be increased Typically this should just be a fraction of the drive current or zero Control Mode 30 PARAM CONTROL MODE choice Chopper Open loop or Chopper Closed loop PWM This parameter specifies Chopper mode or PWM mode Chopper mode monitors the winding current while the winding is on When the current reaches the target value Drive Current it switches the winding off The winding remains off for the Off Blanking Time At the end of the blanking time the winding is turned on again and the current monitoring resumes In Open loop PWM mode the duty cycle is calculated to set the voltage applied to the winding such that the target Drive Current flows in the winding However this is for a steady state situation and when the motor is turning its impedance changes dynamically This means that the PWM current control is not precise Also by applying less than the full bus voltage to the winding when it is turned on it can take a long time before the drive current is reached For this reason the winding can be left with full voltage applie
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32. meets the following specifications Electrical Supported motor type Bipolar stepper Motor current rated current per coil 3 Amps Motor voltage continuous coil voltage 1 80 Supply Voltage 9 80 Mechanical 4 6 x 2 8 x 0 75 117 mm x 71 mm x 19 mm No heat sink necessary 12 November 4 2009 User Interfaces The Stepper RDK firmware provides control of the stepper motor It makes use of many of the features of the Stellaris microcontroller to perform the stepping function reducing the number of external parts needed In addition the stepping firmware can be integrated with the user s application eliminating the need for separate microcontrollers for the stepping and application functions The Stepper RDK firmware generates a stepping sequence as needed to run the motor at the specified speed It also computes acceleration and deceleration ramps to smoothly change the motor speed between stopped and target speed It switches voltage to the control signals of the H bridge in order to drive the correct current to the motor windings at each step in a stepping sequence The Stepper RDK firmware can be controlled in two ways The simplest way is using the on board interface which allows the user control of the motor speed or position using controls available on the RDK board For more complex control a PC hosted graphical program is available which not only allows setting of speed and positio
33. n but also a number of other parameters for tuning the motor operation see Graphical User Interface on page 15 On board User Interface The on board user interface provides a way for the user to operate the stepper motor using just the controls provided on the stepper RDK board The controls that can be used are a potentiometer a push button and two LEDs See Figure 2 1 for a photo of the on board controls Figure 2 1 On board User Interface JTAG SWP Reset Button connector LED Status Power LEP user Button Potentiometer November 4 2009 13 User Interfaces The on board user interface can operate in two modes Speed mode and Position mode In Speed mode the motor runs continuously at a speed and direction that can be controlled by the user In Position mode the motor runs to a position controlled by the user The starting mode is Speed mode The following on board controls are available Reset button Restarts the stepper software The software enters Speed mode User button Switches between on board UI modes and starts and stops the motor To change modes hold down the user button for five seconds To start and stop the motor press and release the button If a fault occurs the status LED is blinking rapidly press and hold the user button for five seconds to clear the fault Doing this will not change modes Potentiometer knob The potentiometer is used to adjust the speed of the
34. ntroller to control the magnitude and polarity of the current in the motor Each H bridge has three logic control signals and PH x2 control whether the high side or low side switch is on A common active low enable signal can force all switches off To turn on the high side MOSFETS the gate voltage must be driven higher than the source This is achieved by using a gate driver and a flying or bootstrap capacitor Using Phase A1 as an example When the low side MOSFET Q4 is ON diode D7 is forward biased and capacitors C16 and C18 charge to almost 15 V In turn this charge allows the high side MOSFET Q3 to be turned on by the high side gate driver As the high side MOSFET turns on its source voltage rises taking the negative terminal of the flying capacitor along with it The capacitor is sized to maintain high side supply voltage of at least 12 5 V during the ON state If the capacitor discharges below 11 3 V typ the SPM s under voltage lock out circuit activates to prevent the MOSFET from moving outside its safe operating area SOA Two 100mQ resistive shunts provide 100 mV A current sensing The resultant voltage is fed into an operation amplifier and into the comparator circuit on Page 2 Table 3 1 Current Monitoring Circuits Microcontroller Microcontroller ADC Comparator 5 Software programmable Measurement of phase Function current trip current amplitude Amplifier Gain 11
35. oidally over a sequence of 8 microsteps per step In Wave Step mode full steps are made as in Full Step mode except that only one winding is energized at a time The unloaded motor runs smoother at slower speeds using half stepping but full stepping may be appropriate for higher speeds For very slow speeds less than 200 steps per second Micro Step mode may be used to smooth out the motion of the motor Off Blanking Time PARAM BLANK OFF uS 20 10000 100 If Chopper mode is used this parameter sets the amount of time that the winding remains off after the winding current reaches the drive current Caution Great care should be taken if decreasing this value If the off blanking time is not long enough the current may not drop enough between the times when the voltage is applied and the current can continue to rise in the winding above the rated current Use lab equipment to observe the winding current when making adjustments to this value November 4 2009 31 32 November 4 2009 Schematics This section contains the schematics for the LM3S1968 Evaluation Board Contents Page on page 34 B Microcontroller on page 35 W Driver Coil A on page 36 W Driver Coil B on page 37 Power Supplies and USB on page 38 November 4 2009 33 6 U Stepper Microcontroller Stepper Microcontroller SchDoc U_Stepper Ph A Drive Stepper Ph A Drive SchDoc History
36. primary functions Motor current control Real time chopper control of motor current Motor step sequencing Controlling the stepper motor s commutation sequence Motor velocity and position control Calculates motor speed as it advances to a new position Serial communication Command and measurement exchange with host device The user can add software to implement additional functions that take advantage of the unused microcontroller peripherals or integrate the stepper control code with a custom application Chopper Control 24 Figure 3 3 shows how the chopper waveform is generated GPIO signals from the microcontroller turn on the MOSFET switches causing the motor current to start to build The rate of increase in motor current is dependent on motor characteristics motor load and the supply voltage Once the ADC detects that the current has exceeded the threshold a blanking time commences The blanking time allows the current to collapse slightly before the cycle repeats November 4 2009 Stellaris amp Stepper Motor RDK User s Manual Figure 3 3 Chopper Waveform Generation 4 Blanking gt Blanking Time Time High side MOSFET ON Control Signal to Gate Driver Low side MOSFET ON Sampling Current Threshold Motor Winding Current Amps Start of step Chopping continues to end of step gt A summary of the current control software is shown in
37. products are not authorized for use in safety critical applications such as life support where a failure of the TI product would reasonably be expected to cause severe personal injury or death unless officers of the parties have executed an agreement specifically governing such use Buyers represent that they have all necessary expertise in the safety and regulatory ramifications of their applications and acknowledge and agree that they are solely responsible for all legal regulatory and safety related requirements concerning their products and any use of TI products in such safety critical applications notwithstanding any applications related information or support that may be provided by TI Further Buyers must fully indemnify TI and its representatives against any damages arising out of the use of TI products in such safety critical applications TI products are neither designed nor intended for use in military aerospace applications or environments unless the TI products are specifically designated by TI as military grade or enhanced plastic Only products designated by TI as military grade meet military specifications Buyers acknowledge and agree that any such use of TI products which TI has not designated as military grade is solely at the Buyer s risk and that they are solely responsible for compliance with all legal and regulatory requirements in connection with such use TI products are neither designed nor intended for use in automotive app
38. rial applications is known as a hybrid stepper motor because it combines attributes from PM and non PM motor construction Figure 1 1 Stepper Motor Double stack motor has 2 sets of magnets 50 rotor teeth Stator teeth on each pole South pole Stator coils Front bearing The rotor on a hybrid stepper motor typically has 200 teeth made from a suitable magnetic material and surrounding one or more powerful embedded magnets As the stator phase is energized the opposing pole in the next rotor tooth is attracted resulting in a single step Note that the torque curve of stepper motors is far from linear see Figure 1 2 For each step the motor develops peak torque when the rotor teeth are offset by one quarter tooth pitch from the opposing pole in the energized phase Also overall motor torque drops considerably as motor speed increases For this reason stepper motor torque is specified as the holding torque or torque with no angular motion 10 November 4 2009 Stellaris amp Stepper Motor RDK User s Manual Figure 1 2 Stepper Speed Torque Curve 160 140 120 N 400 steps rev E 100 N 1 10 Stepping 8 80 O c n 150 200 450 600 750 900 1050 1200 1350 1500 Hz 400 steps rev 1 000 2 000 3 000 4 000 5 000 6 000 7 000 8 000 9 000 10 000 Hz 2000 steps rev 5 000 10 000 15 000 20 000 25 000 30 000 35 000 40 000 45 000 50
39. rrent Sens p High Low Side Motor A1 Potentiometer Gate Driver MOSFET Pair Speed Pos Adjust gt m Current Sense Ampl Mode gt High Low Side gt Motor A2 PUSH Gate Driver MOSFET Pair D Stellaris o Microcontroller High Low Side Motor B1 A n otor Spare GPIO CA Gate Driver MOSFET Pair i B Current Sense Ampl JTAG SWD High Low Side Motor B2 4 Gate Driver MOSFET Pair Current Sense Functional Description Stepper motor controls normally use a dedicated controller chip to implement a chopper based drive stage The microcontroller if present is there to manage position control and send step pulses to the controller The RDK implements all of this functionality in the Stellaris microcontroller One of the benefits of a software implementation is that the rest of the circuit is simple and can use standard power semiconductors This section contains a detailed description of the RDK s operation See Appendix B Schematics starting on page 33 for more details Microcontroller Schematic Pages 1 2 At the core of the Stepper Motor RDK is a Stellaris LM3S617 microcontroller This part has a peripheral set optimized for motor control including 6 high speed ADC channels a motor control PWM block and an analog comparator
40. sed 6 Maximum Current Sets a fault current level If the current rises above this level the hardware triggers a fault and places the motor in a safe configuration 20 November 4 2009 CHAPTER 3 Hardware Description Key components in the reference design include a Stellaris LM3S617 microcontroller with an ARM Cortex M3 core and a power stage consisting of Fairchild Semiconductor s gate drivers and MOSFETs Other complementary components complete the design by providing protection signal acquisition and power supply functions The entire circuit is built on a simple two layer printed circuit board see Figure 3 1 All design files are provided in the CD Figure 3 1 Stepper Motor Control RDK Layout DC Power In 255 Output to Motor USB Interface DC Bus Capacitors PC Fairchild MOSFETs Gate Drivers Power Supplies Stellaris Microcontroller EX 3 7 2 2 e w ey W sPorosg SWD 24 osos ge Speed Pot LUMINARYMIORO STEPPER MOTOR CONTROL RDK 1 xd Mode Switch November 4 2009 21 Hardware Description Block Diagram Figure 3 2 Block Diagram 9 80V DC IN 15V 3 3V Linear Hall effect Sensor Switching Switching Power Supply Power Supply DC Bus Capacitors J USB to Serial QD DC Voltage Sensi Ji Cu
41. t Motor Parameters 2 Decay Mode Slow In Slow Decay mode during the time that no voltage is applied to the winding the low side switches on the H bridge are closed This allows current to continue to circulate in the winding and decay slowly Fast In Fast Decay mode during the time that no voltage is applied to the winding all the switches are open The current can no longer circulate and decays quickly 3 Step Mode Full With full stepping voltage is always applied to both windings and a four step stepping sequence is used Half With half stepping the voltage is off during part of the stepping sequence and an eight half step stepping sequence is used Micro With micro stepping the whole step is divided into 8 micro steps The current applied to the windings is varied sinusoidally piecewise at each micro step time Wave Wave stepping is the same as full stepping except that voltage is applied to only one winding at a time 4 Holding Current This is the amount of current that should be applied to the windings when the motor is stopped This increases the holding torque of the motor Typically this value should be 0 or a fraction of the drive current 5 Winding This is the winding resistance of the motor that is used This value Resistance should be entered by the user if the motor type is changed This value is used in order to calculate the correct PWM duty cycle if PWM control mode is u
42. t Rev Issue 3 6 10 07 Bill Of Materials c gem C35 C39 C52 Dd E 25 49 47 48 50 p apacitor D o Ceramic C21 C33 2 Capacitor 1000 50 10 C ic 0805 4 5 7 9 pL Capacitor 0 01uF 16V 1096 0805 X7R C44 C45 C41 C42 EEV FK2A151M Capacitor 150uF 50V Electro Low Z SMT Size G C14 15 14 C0805C104 5RACTU Capacitor 0 1uF 50V 5 0805 X7R C16 C17 C27 C28 C29 C30 C37 C38 C40 C51 C22 C34 C36 E Capacitor 0 1uF 100V 10 1206 X7R Kemet C43 10 D1 D2 D3 D7 10 5100 Diode Schottky 100V 2A Fairchild D8 D9 D10 D11 D12 D13 04 25 26 3 5 171 LED 0805 SMT Green 154004 Fuse SMT in holder 4A Littelfuse 13 FB2 FB3 2 BLM21PG221SN1D Inductor Chip Ferrite 2A 0805 220 Murata Ohm 100MHz N2520 6VOC RB WE Header Low profile Shrouded 2x10way SMT 3M UI 43045 0409 Connector MicroFit 3mm 4pos header R A SMT Molex PJ 002AH SMT Connector 2 1mm DC power socket SMT 6 Molex Coiltronics Coiltronics Fairchild 21 Q3 Q4 Q5 Q6 Q9 Q10 Q11 FDMS3672 Mosfet Dual N Ch 100V 5 1A SO 8 Fairchild Q12 R4 R5 R6 R7 16 Resistor 10K 596 0805 Generic R8 R9 R13 R16 R17 R18 R30 R32 R33 R45 R48 R50 Pat Po Resistor 47K 5 0805 Generic R10 11 R12 Resistor 220 Ohms 5 0805 Generic R14 R47 2 Resistor 4 7K 5 0805 Generic EVU TUAB16B54
43. to flash memory Configuration Window Use the Configuration window to adjust specific motor parameters Open the Configuration window by clicking the Configure button on the main window In the Configuration window change the parameters and click the OK button to send the new parameters to the target Click the Cancel button to discard any changes 18 November 4 2009 Stellaris amp Stepper Motor RDK User s Manual Figure 2 3 Configuration Window Stepper Motor Properties Control Mode Fixed Rise Time 5 PWM Frequency 1 Open loop PWM 4500 Chopper Closed loop PWM Chopper Off Blanking Time 5 100 Motor Parameters Decay Mode Holding Current m Fast 2 2 Slow E g Winding Resistance mOhm Step Mode Ful Half 3 C Micro C Wave Table 2 2 Description of Configuration Controls 1 Control Mode Open loop PWM In Open loop PWM control mode the firmware sets the PWM duty cycle to a value that corresponds to the desired current The duty cycle is calculated based on the winding resistance and the bus voltage There is no actual measurement of the winding current In PWM mode the Fixed Rise Time parameter can also be used see Fixed Rise Time Chopper In Chopper control mode the microcontroller firmware monitors the current flowing in the winding and switches t
44. tor position can be set in two ways first by entering a value in the Target Position box or by clicking on the position slider and dragging it right or left to the desired position and then releasing it The position control is not available until the motor has been enabled using the Run button Actual Shows the position of the motor in steps The position is shown both in the Actual box and also on the slider control There is an indicator on the upper slider that moves to show the actual motor position Graph Area Speed Graph This strip chart shows the speed of the motor over time The entire graph shows 30 seconds of motor speed history The graph is signed showing the direction as well as the speed of the motor Current Graph This strip chart shows the current in the motor windings over time The entire graph shows 30 seconds of winding current history This graph shows the peak current in the windings averaged between the two windings The current data is only available when Chopper mode is used If PWM mode is used then this strip chart is grayed out Position Slider Control Move the slider to adjust the motor s position The bottom part of the slider can be dragged with the mouse to set the target position The upper part of the slider indicates the actual position November 4 2009 Table 2 1 6 Stellaris amp Stepper Motor RDK User s Manual Description of GUI Main Window
45. using either the RDK GUI software or using a JTAG debug interface available from leading development tools vendors Features The Stepper RDK s primary application is driving NEMA17 NEMA23 and 4 stepper motors rated at up to 80 V at 3 Amps The Stepper RDK uses software based chopper control in order to operate the motor at both high torque and high step rates The Stepper RDK has the following features November 4 2009 Advanced chopper control of bipolar stepper motors Flexible platform accelerates integration process Fast and slow decay modes Full Step Half Step Micro Step and Wave modes High step rates up to 10 000 steps sec with suitable motor Programmable holding current Integrated USB Virtual COM port Bootloader for firmware upgrades over serial port Support for external debugger through standard 20 pin ARM header Stellaris amp Stepper Motor Reference Design Overview Motor Technology Introduction to Stepper Motors Stepper motors are synchronous DC motors which rotate in precise increments as their coils are energized Stepper motors typically have step angles of 0 9 1 8 7 5 15 The motor in the RDK has a step angle of 1 8 for a total of 200 steps per revolution Figure 1 1 shows a detailed photo of the NEMA23 stepper motor included in the RDK There are several different families of steppers motors some with and some without permanent magnets PM The most common type in indust
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