ID630L: Becoming Familiar with Sensorless Vector Control of BLDC Motors

Transcription

1 ID630L: Becoming Familiar with Sensorless Vector Control of BLDC Motors Description: This lab will teach the attendees how to use Renesas MCU to implement sensorless vector control of BLDC motors step by step. Lab Objectives After the Lab the attendee will be able to: 1. Use the real time watch window for the embedded control development. 2. Understand ADC sampling to measure the motor currents through 3-shunt and DC bus voltage. 3. Drive the motor with open loop. 4. Understand Sensorless position and speed estimation. 5. Closing the Speed Loop & Using GUI Estimated Speed. Lab Materials Please verify you have the following materials at your lab station. SH7216 Motor Control Demo Kit Two black USB Cables, one has two USB plugs at one end. Laptop with HEW v4.08, SH2A compiler and E10A driver E10A Debugger. Skill Level Attendee should have experience with: 1. Motor control techniques 2. Sensorless vector control concepts 3. Ability to use HEW Time to Complete Lab 90 Minutes Lab Sections Set up Sensorless Vector Control Demo.2 Time to complete task: 10 minute Sample Motor Currents and DC Bus Voltage.7 Time to complete task: 15 minutes Drive the Motor with Open Loop. 10 Time to complete task: 20 minutes Understand Sensorless Position and Speed Estimation..14 Time to complete task: 20 minutes Drive Motor with Closing Speed using Estimated Speed by GUI...17 Time to complete task: 25 minutes Get Familiar with Sensorless Vector Control of BLDC Motors Page 1 of 19

2 1 Set up Sensorless Vector Control Demo Overview: This section will cover setting up Sensorless vector control demo. Procedural Steps Step 1.1 Connect E10A debugger to the Laptop using the black USB communication cable. Plug the E10A ribbon cable to the center Header (as shown). Also attach the second USB cable to 2 USB ports on the laptop, and the USB jack on the Target. (as show) Figure 1 The Dual USB cable provides power to the Target. The E10A cannot power the Target. Step 1.2 Step 1.3 Open HEW from the Desktop. Load the Sensorless vector control demo project, found in the workspace directory (C:\WorkSpace\DevCon_Lab\MCRP07_7216_DevCon_Lab.hws), and then click ok. Figure 2 Get Familiar with Sensorless Vector Control of BLDC Motors Page 2 of 19

3 Step 1.4 Use Debug Connect, to enable HEW to connect to the E10A debugger. Step 1.5 HEW will pop up an Emulator window, set Device = R5F72167AD, select E10A USB Emulator, and hit OK. The E10A emulator will then connect to the board. Figure 3 Writing Flash memory is used to flash the Target to run stand-alone. Step 1.6 Step 1.7 When asked to Please reset the user system press the Yellow RESET button near the E10A header, and hit Enter. Leave the clock at 12.5Mhz and hit OK. Figure 4 Get Familiar with Sensorless Vector Control of BLDC Motors Page 3 of 19

4 Step 1.8 Leave input ID Code as E10A and hit OK. Figure 5 Question: 1) What is the result of selecting New ID Code? Step 1.9 Build the project within HEW: [menu] Build >> Build All. The Build process will take about 1 minute. This should return a 0 Errors, 1 Warning message, (HEW is a demo version and the build size is limited to 256K). Step 1.10 You will be prompted to download the program to the board. Answer Yes. Step 1.11 Now that the SH2A Target is connected and Flashed with the newly built Sensorless Vector Control Program, Run it with HEW: [menu] Debug >> Step 1.12 Open The Motor Control Demo GUI Interface from desktop. Reset Go. Get Familiar with Sensorless Vector Control of BLDC Motors Page 4 of 19

5 Step 1.13 A board connection window opens. Select Auto Detect and hit Connect. Figure 6 This GUI communicates with the Sensorless Vector Motor Program currently running on the SH2A Target, via the SH2A USB Port and a Monitor subroutine (in module userif.c). The GUI will disconnect when the Target Program is Halted for any reason. Simply Reconnect once the Target is Running again. Step 1.14 After Connecting, the GUI user interface will pop up as: Figure 7 Get Familiar with Sensorless Vector Control of BLDC Motors Page 5 of 19

6 Step 1.15 Use the Cursor on the RPM control to spin up the motor (as shown). Step 1.16 Set the RPM to 0. Figure 8 Get Familiar with Sensorless Vector Control of BLDC Motors Page 6 of 19

7 2 Sample Motor Currents and DC Bus Voltage Overview: This section of the lab will focus on sampling the input variables, which are required for sensorless vector control. The user will observe the initialization of the 12-bit ADC registers and learn how to sample motor currents and DC bus voltages. Once the ADC conversions are available, the motor currents and DC bus voltage may be displayed in a real time watch window. Procedural Steps Step 2.1 Press Stop the Halt the Target. Step 2.2 Step 2.3 Now use [menu]>>file>> Save Workspace and Save Session. (you should get into the habit of periodically saving your HEW sessions). Use the Navigation Tab (on Left Window), to locate the C Function MC_SetOFF(). Figure 9 The function MC_SetOff(void) wakes up ADC and if it selects ADC channel 0 (iu) and channel 4 (iw). It also configures the ADC to be triggered by PWM Timer TRG4A and TRG4B. Get Familiar with Sensorless Vector Control of BLDC Motors Page 7 of 19

8 Step 2.4 Locate Variables ium_off, ivm_off, iw0_off, and iw4_off. Add these four variables to a C Watch window. These correspond to iu and iv (or ia and ib) in the diagram below. (hint: right click on each variable and hit Add Watch ) Step 2.5 Restart the program execution with [menu] Debug >> Reset Go. Step 2.6 Step 2.7 Halt the program execution. Read and Record the current offset values in the real time watch windows. Record: ium_off, ivm_off, iw0_off =, iw4_off = Question: Thinking of the System Diagram What would be the purpose of these four offsets? DC Bus * ω r ω r Δω r Speed Regulator i d * = 0 i d * i q i q iq PI Regulator id PI Regulator * U q * U d d,q to α, β T 1 ( θ) * U α * U β α,β to a, b, c SIN PWM PWM1~6 Voltage Source 3-phase Inverter θ Motor Model Based Flux and Position Observer i q i d α,β to d,q T (θ ) i α i β u,v,w to α,β i u i v ω r Speed Estimation θ 3-phase PMSM Figure 10 Step 2.8 Step 2.9 In the Edit Window, Locate the function of MC_readc_ts(signed short *u, signed short *v, signed short *w) This routine parses the 3-shunt motor currents and the DC Bus Voltage. Now locate the function that is calling this routine. HINT: use the Find In Files Feature of HEW to locate MC_readc_ts. You will find the subroutine call in the MC_Closed_Loop(void) subroutine (motorcontrol.c ~line 1320). Get Familiar with Sensorless Vector Control of BLDC Motors Page 8 of 19

9 Step 2.10 Add the Motor Current Variables (ium_ad, ivm_ad, and iwm_ad) to the C Watch Window. Step 2.11 Also add the DC Bus Voltage (vbus_ad) to the C Watch Window. Step 2.12 Configure all of the C Watch Variables to update continuously by hi-lighting the variable, and clicking on the R (changing each R to an R) Step 2.13 Restart the program execution with [menu] Debug >> Reset Go. Step 2.14 Reconnect the Motor Demo GUI, and start the motor spinning at about 3000 RPM. Step 2.15 Record the motor currents and DC bus voltage values in the real time watch windows. Record: MIN MAX ium_ad = ium_ad = ivm_ad = ivm_ad = iwm_ad = iwm_ad = vbus_ad = vbus_ad = Step 2.16 Press Stop the Halt the Target. Note: IW is wired into both AD0 and AD1. Why? Because the SH2A can do simultaneous conversions on AD0 and AD1, so by having IW wired to both AD Units, the software can to simultaneous conversions on any two phases: IU and IV, IU and IW4, IV and IW0. Get Familiar with Sensorless Vector Control of BLDC Motors Page 9 of 19

10 3 Drive the BLDC Motor with Open Loop Overview: This section of the lab will setup the motor running with the constant speed and constant terminal voltage. The objective is observe the interaction of Commanded Open Loop Speed and Vector Voltages Vdc and Vqc. Procedural Steps Step 3.1 Open intprg.c, and locate the Interrupt Vector 192 of Line 493. Step 3.2 Un-Comment the Call to MC_ConInt_OPEN_LOOP and Comment out the call to MC_ConInt_CLOSE_LOOP. 493 // 192 MTU2 MTU4 TGI4V 494 void INT_MTU2_MTU4_TGI4V(void){ MC_ConInt_OPEN_LOOP(); } 495 //void INT_MTU2_MTU4_TGI4V(void){ MC_ConInt_CLOSE_LOOP();} The PWM interrupt runs at the carrier frequency, and is used to call each of the control loops Step 3.3 In the header file of motorcontrol.h, change the values of Speed_Open, Vdc_Open, and Vqc_Open, to match those shown below: /* open loop or close loop */ 43 #define Vdc_Open 3 //open loop voltage 3V 44 #define Vqc_Open 3 //open loop voltage 3V 45 #define Speed_Open 350 //open loop speed 350rpm Step 3.4 Save and Build All the project. Don t bother to Download to Target this time. Get Familiar with Sensorless Vector Control of BLDC Motors Page 10 of 19

11 Step 3.5 Tired of waiting for the C Runtime library to build every time? Let s start using that runtime library that we ve created. Open the Build Options [Menu]>>Build>>SuperH risk Engine Standard Toolchain>>StandardLibrary>>Mode. Set to Use an existing library file and press OK. Figure 11 Step 3.6 Save, Re-build and reload the MCU in one step, by selecting [menu] Build >> Build All. (wasn t that much faster?) Step 3.7 Restart the program execution with [menu] Debug >> Reset Go. Step 3.8 ReConnect the Motor Demo GUI, and set the RPM to ~2000. Step 3.9 Check if the motor runs. If the motor doesn t run, just vibrates, jitters, or otherwise runs choppy, increase given voltage values (>= 3) until it runs smoothly. Rebuild each time you make a change to motorcontrol.h. Hint: Occasionally when the motor freezes, the Motor Demo GIU Disconnects. When this happens, Stop the Target, Reset the Target, press the USB reset button. Now you can Re-build and/or Run, and reconnect the GUI. Step 3.10 Find the value of Motor Speed from GUI PERPROTY MONITOR if it is close to the given speed. Get Familiar with Sensorless Vector Control of BLDC Motors Page 11 of 19

12 Record Motor Speed from PROPERTY MONITOR Motor_Speed: Question: Does the motor speed run at the given speed? Step 3.11 Change the value of Speed_Open from 200rpm to 400rpm. Step 3.12 Re-build and Run. Reconnect the GUI, and attempt to start the motor. Did it run? Step 3.13 Continue to increase the value of Speed_Open, until the motor fails to operate (repeat steps ). Record the last working value below. Max Value of Speed_Open: Question: The motor is failing to run at a much slower speed now. Why? Step 3.14 Add Comments and Un-Comment the 4 lines shown below (in motorcontrol.c ~line 1401) 1401 vdc=vdc_open_ram<<5; 1402 vqc=vqc_open_ram<<5; 1403 // vdc=vdc_open<<5; // vqc=vqc_open<<5; Step 3.15 Comment out and Un-Comment the 2 lines shown below (in motorcontrol.c ~line 1451) 1451 startup_phasel+=(speed_open_ram<<10)/1/125; // angle management 1452 // startup_phasel+=(speed_open<<10)/1.125; // angle management Step 3.16 Save, Build, and Re-Load the project. Step 3.17 Add Vdc_Open_RAM, Vqc_Open_RAM, and Speed_Open_RAM to your C Watch Window. Get Familiar with Sensorless Vector Control of BLDC Motors Page 12 of 19

13 Figure 12 Step 3.18 Run the Target, and Reconnect the GUI. Step 3.19 Using the Watch Window, Poke new values into Speed_Open_RAM, Vdc_Open_RAM, and Vqc_Open_RAM, on-the-fly, without having to rebuild and reload each time. Question: The motor will operate even when Vqc_Open = 0. Why? Step 3.20 Halt the Target and Press the USB Reset button. Step 3.21 Remove all of the variables from the C Watch Window. Get Familiar with Sensorless Vector Control of BLDC Motors Page 13 of 19

14 4 Understanding Sensorless Position and Speed Estimation Overview: This section is a key part of this lab, which teaches the user the core Sensorless technology to estimate the motor position and speed. Procedural Steps Step 4.1 Step 4.2 In motorcontrol.c, find the subroutine calls McrpLib_PhaseEst(old_va, old_vb, iam, ibm, r_sta, l_syn, &Phase_est); and McrpLib_SpeedEst(Phase_est, (SAM_FRE_HZ/8.0), 8). Use the Go To Definition Of McrpLib_PhaseEst, to find the source code for this routine. Question: Why is the source for these two routines = No definition exists? Step 4.3 Since these two routines are located in the MCRP07_Lib_001.lib file (I just answered that question, didn t I?), the source code isn t part of this project. Open the file mcrplib.h and locate the definitions for these two library calls. Note: The Library source code will be available to users. Although it is free, it does require an NDA and Software License Agreement (still free). Step 4.4 Set Speed_Open = 350, Vdc_Open = 3, and Vqc_Open = 3. Step 4.5 Step 4.6 Save, Build, and Download. Add the variable mec_rpm to the C-Watch window. Enable the Auto-update for this variable (R ) Run the Target, and Reconnect the GUI. Insure that the motor runs. Record the highest and lowest values seen, in the box below. Record mec_rpm (with McrpLib_SpeedEst2() Highest Lowest Step 4.7 Change the Software to call to the speed estimator to use McrpLib_SpeedEst3. (in motorcontrol.c ~line // Speed_est=McrpLib_SpeedEst2(Phase_est); 1433 Speed_est=McrpLib_SpeedEst3(Phase_est); Get Familiar with Sensorless Vector Control of BLDC Motors Page 14 of 19

15 Step 4.8 Save, Build, Download, Run, and Reconnect the GUI. Spin the Motor up again. Record the highest and lowest values of mec_rpm seen in the watch window. Record mec_rpm (with McrpLib_SpeedEst3() Highest Lowest This Speed Estimate appears to be more erratic. Why do you think this is? (hint: look at the descriptions of the Library functions). Step 4.9 Locate the #defines shown below. These are in customize.h. /* MCRP07 12V motor parameters */ #define RPM_MIN_CUSTOM 2000 // 200 < X < 5000 // min speed in rpm #define RPM_MAX_CUSTOM 5000 // 1000 < X < // max speed in rpm #define R_ACC_CUSTOM 1000 // 1 < X < // accel. ramp in rpm/sec #define R_DEC_CUSTOM 1000 // 1 < X < // accel. ramp in rpm/sec #define C_POLI_CUSTOM 4 // 1 < X < 4 // polar couples number #define I_START_CUSTOM 2 // 0 < X < 5000 // startup current in (pk)/amp_div #define IQ_MAX_CUSTOM 2 // 0 < X < 5000 // max torque current in(pk)/amp_div #define R_STA_CUSTOM 23 // 0 < X < 5000 // stator phase res. in Ohm/OHM_DIV #define L_SYN_CUSTOM 50 // 0 < X < 5000 // synchronous ind. in Henry/HEN_DIV Step 4.10 In the Motor Demo GUI Interface, press the Setup button on the right side of the screen. Figure 13 Get Familiar with Sensorless Vector Control of BLDC Motors Page 15 of 19

16 Step 4.11 Scroll up and down through these parameters, and you notice that they mirror the #defines in the customize.h file. You can make changes to the settings, and Write to RAM, but this does NOT change the customize.h file. The original values will be restored upon RESET. Figure 14 Step 4.12 Set the motor speed to Zero. Halt the Target, and Press the USB Reset button. Get Familiar with Sensorless Vector Control of BLDC Motors Page 16 of 19

17 5 Closing the Speed Loop & Using GUI Estimated Speed Overview: This section will teach the user how to use the GUI to drive the motor while closing both speed and current loops which use the estimated position and speed. Procedural Steps Step 5.1 Open intprg.c, and locate the Interrupt Vector 192 of Line 493. Step 5.2 Un-Comment the Call to MC_ConInt_CLOSE_LOOP and Comment out the call to MC_ConInt_OPEN_LOOP. 493 // 192 MTU2 MTU4 TGI4V 494 void INT_MTU2_MTU4_TGI4V(void){ MC_ConInt_OPEN_LOOP(); } 495 //void INT_MTU2_MTU4_TGI4V(void){ MC_ConInt_CLOSE_LOOP();} Step 5.3 Save, Re-build and reload the MCU in one step, by selecting [menu] Build >> Build All. Step 5.4 Run the Target and Reconnect the GUI. Spin up the motor. Record the highest and lowest speed values seen if it can track the reference speed, in the box below. Record Motor Speed from PROPERTY MONITOR Highest Lowest Question: Does the motor speed track the given speed setting? Step 5.5 In the header file of customer.h, note that the speed and current PI gains are set as shown below. These are the Current Loop and Speed Loop Proportional and Integral default gains. #define KP_CUR_CUSTOM 160 // 0 < X < // K prop. current control #define KI_CUR_CUSTOM 30 // 0 < X < // K integ. current control #define KP_VEL_CUSTOM 80 // 0 < X < // K prop. speed control #define KI_VEL_CUSTOM 100 // 0 < X < // K integ. speed control Step 5.6 In the GUI Interface dial the RPM control up and down, monitoring the Reference and Measured Speed Plots, and check if the actual speed can follow the reference speed, Get Familiar with Sensorless Vector Control of BLDC Motors Page 17 of 19

18 Step 5.7 Stop spinning the motor set RPM = 0. Step 5.8 In the GUI, press the Setup button and Reload the parameters. Step 5.9 Change the Current Loop Kp setting to 500. (Let s really take it for a walk!). Press Write, and Close. Step 5.10 Now Spin up the motor. Record your results of motor speed and CURRENT below: Record Motor Speed from PROPERTY MONITOR Highest Lowest Question 1: Is the motor speed is much slower or does it track the desired speed setting? The motor is also much harder to stall. Why is this? Question 2: With the Current Loop Kp set too high, did the motor track the reference speed? Figure 15 Get Familiar with Sensorless Vector Control of BLDC Motors Page 18 of 19

19 Step 5.11 Set the Current Loop Kp back to 160. Note that you can make this change on-the-fly. Step 5.12 Through the GUI, change the motor speed and add a load to the motor. Continue to experiment with the Current Loop and Speed Loop proportional and integral gains (Kp & Ki). The motor speed and motor dq current display in the GUI graphics. End of Lab, Thank you! Get Familiar with Sensorless Vector Control of BLDC Motors Page 19 of 19