Selected electrical drive topics April 2017, Gilze The Netherlands DC Drives, encoderless FOC control of Drones, Hybrid stepper motors and BLDC machines using StEmbed Instructor: Prof. Dr. ir. D.W.J. Pulle - University Professor : RWTH-ISEA, Aachen Germany - CEO EMsynergy, Sydney Australia - Member of the Texas Instruments InstaSPIN™ development team Duco W.J. Pulle 1 Details • Reference Textbooks : – Primary Textbook: Pulle D.W.J., Darnell P. and Veltman A. ‘Applied control of Electrical Drives’, 1st edition, 2015 Springer – Secondary Textbook: Veltman A., Pulle D.W. J. and De Doncker R.W. 'Fundamentals of Electrical Drives', 2nd edition, 2016 Springer – Additional Textbook: De Doncker R.W., Pulle D.W.J. and Veltman A. 'Advanced Electrical Drives', 1st edition, 2010 Springer • Hardware and Software – Software: Embed and Code Composer Studio (CCS version 6.2) – Laptop with the above mentioned software – Converters: • Texas Instruments LaunchXL-069M module, with 8301 boost pack and 24V supply unit • Texas Instruments DRV 8301-HC module with F28069 ISO control board • Texas Instruments DRV8312 module with F28069 ISO control board – Motors: Anaheim salient PM motor, DC motor ( inside linear actuator), Drone motor, Walkera helicopter motor and 2-phase hybrid stepper motor – Session supported by: – PowerPoint slides – Embed project lab files Duco W.J. Pulle Outline • Drive demonstrations using Embed – Current control of a DC motor drive using a LaunchXL-boost converter – Encoderless FOC control of a drone motor using InstaSPIN and a LaunchXL-boost converter – Encoderless FOC control of a salient PM machine using InstaSPIN and a DRV-8312EMV converter – Encoderless FOC control of a two-phase hybrid stepping motor using InstaSPIN and a DRV-8312EMV converter – Encoderless FOC control of a Walkera V450BD5 model helicopter using InstaSPIN and a DRV-8301-HC converter Duco W.J. Pulle DC motor drive demo Introduction Experimental drive setup: • Texas Instruments LaunchXL with 8301 boostpack • 12 V DC supply • Linear actuator with DC motor inside DC motor parameters (measured with L-C-R meter and Ohm meter) : • Armature resistance: 3.0 π • Armature inductance: 838 ππ― Aim: • Current control of a linear actuator using StEmbed Duco W.J. Pulle 4 DC motor drive demo C2000 MCU + Tx Rx SIMO SOMI CLK STE Serial coms (UART) SPI Serial coms Timers and PWM Compare Units Capture Unit ADC ADC channels shown here may not match those actually in use DC Bus PWM1 PWM2 PWM3 PWM4 PWM5 PWM6 PWM1 PWM3 PWM5 PWM2 PWM4 PWM6 CAP/QEP ADCIN0 ADCIN1 ADCIN2 ADCIN3 ADCIN4 ADCIN5 ADCIN6 DC motor Shunt resistor ADCIN2 Phase Voltage Meas ADCIN1 ADCIN3 Signal Conditioning Duco W.J. Pulle ADCIN4 ADCIN5 5 DC motor drive demo Overall representation of MCU based drive: demo_DCdrive_launchXLphCv1 • • Inputs to this module are: – per unit reference armature current – 'speed_loop_on: activates FOC with speed control when on and FOC in torque mode when 'off' – 'conv _on' : activates converter – 'chan_sel' : selects diagnostic channels to be viewed: ch1-2 or ch3-4 Outputs are: – per unit, DC bus voltage – per unit, armature voltage – per unit, armature current What does the 'controller' module look like internally ? Duco W.J. Pulle 6 DC motor drive demo One level down into the 'controller' Modules present are: • Dialog boxes: 'operation variables' and 'Converter variables' • Main motor control unit: triggered by the ADC conversion unit, running at 15 kHz • 100Hz unit: controls LEDS which show that MCU is operating and current trip on/off. Also executes all background task of the drive. • Diagnostic tool unit: used to look at 4 'test' signals real time , 2x2. User can place 'test' variables to desired locations within 'main motor control unit' to examine signals and set triggering. next: what is the content of the dialog boxes? Duco W.J. Pulle 7 DC motor drive demo Operational Variables Dialog box: motivation for entries shown • • • • • • • FullscaleVoltage(V)= 48: value chosen should be higher then highest bus voltage and less then twice the ADC full-scale voltage of 26.32 V. FullscaleCurrent(A)=20: value higher then the higher then the highest expected current . Value should be less then twice the ADC full-scale current of 33.0 A Max_Duty_cycle_CC= 0.8: maximum value for linear operation (with SVM active) is 1.15. However this converter makes use of shunt resistors for measuring the currents and this limits the duty cycle as a minimum ‘on time’ of the lower switches is required for getting reliable current samples User current_ramp= 500: rate of armature current change Currentcontroller_Kp(V/A)=3.14: Current controller gain set by armature inductance and sample frequency Currentcontroller_wi(rad/s)=2000: Current controller bandwidth set by armature resistance and inductance Current trip(A)=10: software current trip where converter shuts down Duco W.J. Pulle 8 DC motor drive demo Converter Variables Dialog box: motivation for entries shown • • ADC_Fullscale_voltage(V)= 26.314: which corresponds with the LaunchXL-boost hardware setup ADC_Fullscale_current(V)= 33.0: which corresponds with the LaunchXL-boost hardware setup Duco W.J. Pulle 9 DC motor drive demo Overall representation of 'main motor control' module Modules present are: • ‘Current controller', which provides the modulation reference values for the two half bridges that control the motor • ‘Shunt Select', that identifies which of the two half-bridge shunts are used as an input for the current controller (value represents the measured armature current) • ‘ADC-PWM’, which measure the half-bridge currents and lowpass filtered converter voltages • 'Current trip', which shuts down converter if absolute user set value is exceeded next: one level into the ‘Drive Controller' Duco W.J. Pulle 10 DC motor drive demo Implementation of the drive controller Details controller: • inputs: normalized reference current (iddn),measured current (imeas) and the DC bus voltage (Vdcn) • outputs: modulation indices (nmr_ref), (nms_ref) used to drive the half-bridges connected to terminals A and B repectively, of the boost module • 'C-Ramp' controls rate of current change (user defined) next: phase C+, running the drive Duco W.J. Pulle 11 DC motor drive demo Final step needed to achieve real time control: demo_DCdrive_launchXLphCv1_d We need a '-d' version of the previous simulation that can run the 'xxx.out' file Example per unit armature voltage (blue) and armature current Duco W.J. Pulle 12 Drone motor drive demo Introduction Experimental drive setup: • Texas Instruments LaunchXL with 8301 boostpack • 12 V DC supply • EMax2213 motor BLDC motor parameters (measured with L-C-R meter and Ohm meter) : • Stator resistance: 0.1 π • Stator inductance: 11.4 ππ― • PM flux: 0.95 mWb (measured with InstaSPIN) • Pole pairs: 7 Aim: • Sensorless (encoderless) FOC and speed control of a drone motor using StEmbed with InstaSPIN • Stator resistance measurement prior to startup • Measurement of torque and shaft speed Duco W.J. Pulle 13 Drone motor drive demo C2000 MCU + Tx Rx SIMO SOMI CLK STE Serial coms (UART) SPI Serial coms Timers and PWM Compare Units Capture Unit ADC ADC channels shown here may not match those actually in use Drone Motor example DC Bus PWM1 PWM2 PWM3 PWM4 PWM5 PWM6 PWM1 PWM3 PWM5 PWM2 PWM4 PWM6 CAP/QEP ADCIN0 ADCIN1 ADCIN2 ADCIN3 ADCIN4 ADCIN5 ADCIN6 Shunt resistor ADCIN2 Phase Voltage Meas ADCIN1 ADCIN3 Signal Conditioning Duco W.J. Pulle ADCIN4 ADCIN5 ADCIN6 14 Drone motor drive demo Overall representation of MCU based drive: Drone_LaunchXLphCv1 • • Inputs to this module are: – per unit reference frequency, direct and quadrature values – ‘speed_loop_on’ : activates FOC with speed control when ‘on’ and torque control when ‘off‘ – ‘encoderless_on’: use of FAST when ‘on’ and open loop current & frequency control when 'off‘ – ‘force_ang_on’: activates force angle function which simplifies motor start up – ‘Rs_Recalb_on’: enables measurement of the stator resistance prior to startup – ‘Enable_Rs_actual_on’: allows FASt to make use of the measured Rs value – ‘conv _on’ : activates converter – ‘chan_sel’ : selects diagnostic channels to be viewed: ch1-2 or ch3-4 Outputs are: – per unit, DC bus voltage, flux, shaft speed and torque – VR1, Vr2 the stator inductance and stator resistance value in use by FAST – Rs_recalb: measured stator resistance, Ivec: vector current amplitude, CPU_act: percentage CPU time What does the 'controller' module look like internally ? Duco W.J. Pulle 15 Drone motor drive demo One level down into the 'controller' Modules present are: • Dialog boxes: 'operation variables' and 'Converter/FAST variables' • Main motor control unit: triggered by the ADC conversion unit, running at 15 kHz • 100Hz unit: controls LEDS which show that MCU is operating and current trip on/off. Also executes all background task of the drive. • Diagnostic tool unit: used to look at 4 'test' signals real time , 2x2. User can place 'test' variables to desired locations within 'main motor control unit' to examine signals and set triggering. next: what is the content of the dialog boxes? Duco W.J. Pulle 16 Drone motor drive demo Operational Variables Dialog box: motivation for entries shown • • • • • • • FullscaleVoltage(V)= 24: value chosen should be higher then highest bus voltage and less then twice the ADC full-scale voltage of 26.32 V (Boost XL module) FullscaleCurrent(A)=20: value higher then the higher then the highest expected current . Value should be less then twice the ADC full-scale current of 33.0 A (Boost XL module) Max_Duty_cycle_CC= 0.8: maximum value for linear operation (with SVM active) is 1.15. However this converter makes use of shunt resistors for measuring the currents and this limits the duty cycle as a minimum ‘on time’ of the lower switches is required for getting reliable current samples User current_ramp= 100: rate of direct and quadrature reference current change Currentcontroller_Kp(V/A)=0.04: Current controller gain set by stator inductance and sample frequency Currentcontroller_wi(rad/s)=2000: Current controller bandwidth set by stator resistance and statorinductance Current trip(A)=14: software current trip where converter shuts down Duco W.J. Pulle 17 Drone motor drive demo Operational Variables Dialog box: motivation for entries shown (continued) • • • • • • User frequency ramp(Hz/s)= 4000: rate of frequency change of reference speed. Speed controller limit =10: maximum speed controller quadrature current limit (absolute value) Res_est_current A)=1.0: DC current value used to measure the stator resistance at startup User current_ramp= 100: rate of direct and quadrature reference current change Currentcontroller_Kp(V/A)=0.04: Current controller gain set by stator inductance and sample frequency Currentcontroller_wi(rad/s)=2000: Current controller bandwidth set by stator resistance and stator inductance Duco W.J. Pulle 18 Drone motor drive demo Converter and FAST Variables Dialog box: motivation for entries shown • • • Voltage_filter(Hz) =364.69: value chosen must match the corner frequency of the converter low-pass filters used to measure the voltages. The hardware corner frequency should typically be chosen in a range set by the full-scale frequency value and the PWM frequency/10, hence 400-3000 Hz in this case. Speed filter pole(Hz) =50: corner frequency of a low-pass filter that filters the estimated shaft speed. Value should be chosen 5-10 times the bandwidth of the speed controller. Force_angle_freq (Hz)=0.5: The force-angle function assists with start-up and speeds up the synchronizing process between estimated EMF and actual machine EMF vectors. Function must be turned off when speed reversals are required. Duco W.J. Pulle 19 Drone motor drive demo Converter and FAST Variables Dialog box: motivation for entries shown (continued) • • • • • • • • • Direction pole (Hz)= 6: a low-pass filter that filters the estimated EMF waveforms to determine the rotational direction of the shaft. Flux pole(Hz)= 100: a low-pass filter that filters the estimated flux. Flux_est_hold_freq (Hz)= 0.15: this sets a frequency band -0.15 to 0.15 where the estimator ‘freezes’ the estimated flux value. DC bus pole(Hz)=20: a low-pass filter that filters the measured per unit inverse DC bus voltage value π ππ«πͺ. ADC_offset pole (Hz)=1: a low-pass filter that is used to determine the ADC offsets. With a setting of 1 sec, sufficient time should be allowed for the ADC offset routine to determine the steady-state offset values PWMFreq(Hz)=45000: PWM frequency required for the converter, set to 45 kHz. Fsampling(Hz)=15000: Sampling frequency used by the current controller. The ratio between the PWM frequency and the Sampling frequency must be an integer value. Presently this is 3. Fest_Fsampling=1: variables set the sampling frequency used by the FAST estimator. With a value of 1 the estimator frequency is set equal to the current controller value, which is the preferred setting. In this case the estimator frequency will therefore be 15 kHz. Fspeed_Fsampling=15: variables set the sampling frequency used by the speed controller. With a value of 15 the sampling frequency is set to 1/15th of current controller value. In this case the speed controller frequency will be 1 kHz. Duco W.J. Pulle 20 Drone motor drive demo Converter and FAST Variables Dialog box: motivation for entries shown(continued) • • • • • • • • Convergence factor=1.5: a factor which influences the time needed to synchronize the estimated EMF vector with the actual EMF vector. ADC_Fullscale _voltage(V)=26.314: value set by hardware (Boost XL in this case)). Its value must be greater than the highest DC voltage. ADC_Fullscale _current(A)=33.0: value set by hardware (Boost XL in this case). Its value must be greater than the highest current of the motor. Lq(H)=11.4e-6: quadrature axis inductance value of the machine, which in a non-salient PM machine is simply the stator inductance Ls. Its value can be found by using an L-C-R meter or estimated via InstaSPIN. Ld(H)=11.4e-6: direct axis inductance value of the machine, which in a non-salient PM machine is simply the stator inductance Ls. Rs(Ohms)=0.1: Stator resistance of the machine. Its value should be the value measured during Rs recalbration at startup. If Rs recalibration is NOT used, FAST will use this value and this can lead to start up problems in the event that the used value is greater then the actual resistance value (hence better to do Rs estimation at startup if possible) PM_flux_est(Wb)=1.0e-3: the estimated PM flux value of the machine. Found either by motor identification using InstaSPIN or by running the machine ‘open loop’ and estimating the flux level on the basis of the observed peak filtered voltage and known shaft speed. p=7: pole pair number of the machine which is either known, or must be experimentally found. Duco W.J. Pulle 21 Drone motor drive demo Overall representation of 'main motor control' module Modules present are: • ‘Drive controller', which provides the modulation reference values for the halfbridges that control the motor • ‘Amp’ that calculates the current vector amplitude • ‘ADC-PWM’, which measures the half-bridge currents and lowpass filtered converter voltages • 'Current trip', which shuts down converter if absolute user set value is exceeded next: one level into the ‘Drive Controller' Duco W.J. Pulle 22 Drone motor drive demo Implementation of the drive controller Details controller: • Speed controller, provides reference quadrature current on the basis of the reference shaft speed and FAST generated measured speed • FOC controller generates the modulation indices for the converter based on the measured currents and direct/quadrature current setpoints • InstaSPIN module, generates the flux, angle, frequency and torque of the machine • Rs_estimation module, generates the excitation needed to measure the stator resistance at start up and also measures the stator resistance value FOC controller next: phase C+, running the drive Duco W.J. Pulle 23 Drone motor drive demo Final step needed to achieve real time control: Drone_LaunchXLphCv1_d We need a '-d' version of the previous simulation that can run the 'xxx.out' file Example per unit armature voltage (blue) and armature current Duco W.J. Pulle 24 Salient PM motor drive demo Introduction Experimental drive setup: • Texas Instruments DRV8312EMV unit with F2806x ISO control board • 24 V DC supply • Anaheim BLY341S-24V-3000 motor Motor parameters (measured with L-C-R meter and Ohm meter) : • Stator resistance: 0.12 π • Stator inductance direct axis: 284 ππ― • Stator inductance quadrature axis: 320 ππ― • PM flux: 8.12 mWb (measured with InstaSPIN) • Pole pairs: 4 Aim: • Sensorless (encoderless) FOC and speed control of a salient PM motor using StEmbed and InstaSPIN • Stator resistance measurement prior to startup • Measurement of torque and shaft speed Duco W.J. Pulle 25 Salient PM motor drive demo Introduction What types are available? • Classic ‘flux-weakening’ IPM machine: – – – • ‘Flux-enhancement ‘ IPM machine: – – – – • direct axis inductance π³π LESS then quadrature axis inductance π³π Use of expensive ‘rare earth’ magnets Negative direct axis current required to provide a positive torque contribution to the electrodynamic torque ( hence PM fluxweakening) direct axis inductance π³π GREATER then quadrature axis inductance π³π Use of low cost ‘Ferrite’ magnets Positive direct axis current required to provide a positive torque contribution to the electrodynamic torque ( hence PM fluxenhancement) New machine range 1-30 kW being developed by ABB referred to as: πΊπππΉπ΄π Salient issues: – Both require an efficient controller that optimizes the currents for a given torque reference value Next: Current Controller for Salient PM Duco W.J. Pulle Reference: ABB Australia, 2014 IEE Aust Lecture Series 26 Salient PM motor drive demo Current Controller for Salient PM Basic machine equations: π • Torque equation: π»π = (ππ ππ − ππππ ππ ) • Use of ‘Saliency factor’ : π = hence ππ³π π > π, πππ ππππ − πππππππππ ππππππππ π π³π −π³π Optimum drive condition : to maximize Torque per Amp ratio Optimum control point non-salient machine: π = π salient machine: π > π Where π»π is the reference torque value and ππ , ππ are the required direct axis and quadrature axis current values. Duco W.J. Pulle 27 Salient PM motor drive demo Overall representation of MCU based drive: Anaheim_FAST_8312phCv1 • • Inputs to this module are: – per unit reference frequency freq_n, amplitudes: id_n, iq_n and speed slider gains: Kpn, Kin – 'speed_loop_on: activates FOC with speed control when ‘on’ and Torque control when ‘off’ – 'encoderless_on': uses angle estimate from FAST when 'on' and Current & frequency control when 'off' – 'Force_ang_on': activates 'zero speed start' when 'on' – 'conv _on' : activates converter – ‘Rs_Recal’: activates the Rs measurement algorithm at start up – 'chan_sel' : selects diagnostic channels to be viewed: ch1-2 or ch3-4 Outputs are: – Per unit, DC bus voltage, PM flux, shaft speed and torque – Two test variables : vr1, vr2 , that show the direct axis inductance and stator resistance values used by FAST – Id_ref: the direct axis current value generated by the salient current controller – Rs_Recal: the Rs value estimated prior to startup What does the 'controller' module look like internally ? Duco W.J. Pulle 28 Salient PM motor drive demo One level down into the 'controller' Modules present are: • Dialog boxes: 'operation variables' and 'Converter/FAST variables' • Main motor control unit: triggered by the ADC conversion unit, running at 15 kHz • 100Hz unit: controls LEDS which show that MCU is operating and current trip on/off. Also executes all background task of the drive. • Diagnostic tool unit: used to look at 4 'test' signals real time , 2x2. User can place 'test' variables to desired locations within 'main motor control unit' to examine signals and set triggering. next: what is the content of the dialog boxes? Duco W.J. Pulle 29 Salient PM motor drive demo Operational Variables Dialog box: motivation for entries shown • • • • • • FullscaleVoltage(V)= 35: value chosen should be higher than highest bus voltage and less than twice the ADC full-scale voltage of 66.32 V (DRV8312EMV unit). FullscaleCurrent(A)=10: value higher than the highest expected current . Value should be less than twice the ADC full-scale current of 17.277 A (DRV8312EMV unit). FullscaleFrequency(Hz)= 400: value set by highest expected electrical frequency, which is determined by the largest expected shaft speed, typically the rated motor value. Max_Duty_cycle_CC= 0.8: maximum value for linear operation (with SVM active) is 1.15. Userfrequency Ramp(Hz/s)= 20000: value determines the rate of frequency change User Current Ramp(A/s)= 100: value determines the rate of current change for the slider inputs Duco W.J. Pulle 30 Salient PM motor drive demo Operational Variables Dialog box: motivation for entries shown (continued) • • • • • Current controller_Kp (V/A) =4.0: the upper limit gain is set by product of stator d-axis inductance and controller sampling frequency, hence πππ ππ― x 15 kHz=4.26. Typically a value in the order of 25% of the maximum value is used for entry. Current controller_wi (rad/s) =425: the upper limit bandwidth is set by ratio of stator resistance and d-axis stator inductance , hence π. ππ/πππ ππ―=422. Speed controller_limit (Nm)=0.25: value sets shaft torque limit. Shaft torque is determined by π»ππ = π. π π© ππ (ππ·π΄ −( π³π -π³π )ππ ) . The controller sets the required direct and quadrature values based on the PM flux and saliency term: ( π³π -π³π ). Res_est_current A)=0.5: DC current value used to measure the stator resistance at startup Current trip (A) =8: value monitors the currents ππΆ , ππ· and trips the converter when the set value is exceeded. Duco W.J. Pulle 31 Salient PM motor drive demo Converter and FAST Variables Dialog box: motivation for entries shown • • • • • Voltage_filter(Hz) =714.4: value chosen must match the corner frequency of the DRV8312EMV converter low-pass filters used to measure the voltages. Speed filter pole(Hz) =50: corner frequency of a low-pass filter that filters the estimated shaft speed. Value should be chosen 5-10 times the bandwidth of the speed controller. Force_angle_freq (Hz)=0.5: The force-angle function assists with start-up and speeds up the synchronizing process between estimated EMF and actual machine EMF vectors. Function must be turned off when speed reversals are required. Direction pole (Hz)= 6: a low-pass filter that filters the estimated EMF waveforms to determine the rotational direction of the shaft. Flux pole(Hz)= 100: a low-pass filter that filters the estimated flux. Duco W.J. Pulle 32 Salient PM motor drive demo Converter and FAST Variables Dialog box: motivation for entries shown(continued) • • • • • • • • • • Flux_est_hold_freq (Hz)= 0.2: this sets a frequency band -0.2 to 0.2 where the estimator ‘freezes’ the estimated flux value. DC bus pole(Hz)=20: a low-pass filter that filters the measured per unit inverse DC bus voltage value π ππ«πͺ. ADC_offset pole (Hz)=1: a low-pass filter that is used to determine the ADC offsets. PWMFreq(Hz)=30000: PWM frequency required for the converter, set to 30kHz. Fsampling(Hz)=15000: Sampling frequency used by the current controller. The ratio between the PWM frequency and the Sampling frequency must be an integer value. Presently this is 2, Fest_Fsampling=1: variables set the sampling frequency used by the FAST estimator. With a value of 1 the estimator frequency is set equal to the current controller value, which is the preferred setting. In this case the estimator frequency will therefore be 15 kHz. Fspeed_Fsampling=15: variables set the sampling frequency used by the speed controller. With a value of 15 the sampling frequency is set to 1/15th of current controller value. In this case the speed controller frequency will be 1 kHz. Convergence factor=1.5: a factor which influence the time needed to synchronize the estimated EMF vector with the actual EMF vector. ADC_Fullscale _voltage(V)=66.32.314: value set by hardware (DRV8312 in this case). ADC_Fullscale _current(A)=17.277: value set by hardware (DRV8312 in this case). Duco W.J. Pulle 33 Salient PM motor drive demo Converter and FAST Variables Dialog box: motivation for entries shown(continued) • • • • • Lq(H)=320e-6: quadrature axis inductance value of the machine. Its value can be found by using an L-C-R meter. Ld(H)=284e-6: direct axis inductance value of the machine. Its value can be found by using an L-C-R meter or estimated via InstaSPIN. Rs(Ohms)=0.12: Stator resistance of the machine. Its value can be found by using the Rs recalibration routine prior to startup. PM_flux_est(Wb)=8.12e-3: the estimated PM flux value of the machine. Found by motor identification using InstaSPIN. p=4: pole pair number of the machine which is either known, or must be experimentally found. Duco W.J. Pulle 34 Salient PM motor drive demo Overall representation of 'main motor control' module Modules present are: • 'Drive controller', in this case a d,q synchronous current controller, speed controller and FAST software encoder module • 'ADC-PWM unit', which measures the voltages from the shunt resistors, conv. phases and DC bus and controls the three half bridges of the converter • 'Current trip', which shuts down converter if absolute user set value is exceeded next: one level into the ‘Drive Controller' Duco W.J. Pulle 35 Salient PM motor drive demo One level into ‘Drive Controller’ module Details : • FOC controller: – • Speed controller: – • Open loop From FAST (ang) InstaSPIN module that generates: – – – – – • provides the shaft torque reference value which is used by the ‘Salient controller’ that generates the direct/quadrature current references for the FOC controller Angle selection: – – • provides the modulation indices for the converter Inverse DC bus voltage Estimate for flux angle Estimate for flux Estimate for speed Estimate for torque Rs estimation module that generates: – Dc current and Rs value prior to start-up Duco W.J. Pulle 36 Salient PM motor drive demo Final step needed to achieve real time control: Anaheim_FAST_8312phCv1_d We need a '-d' version of the previous simulation that can run the 'xxx.out' file Example per unit ππΆ , ππ· currents, with applied ‘hand’ load Duco W.J. Pulle 37 Hybrid stepper motor drive demo Introduction Experimental drive setup: • Texas Instruments DRV8312EMV unit with F2806x ISO control board • 24 V DC supply • Fulling FL57STH5-2804AC-04 stepper motor Motor parameters (measured with L-C-R meter and Ohm meter) : • Stator resistance: 0.984 π • Stator inductance direct axis: 2.86 mπ― • Stator inductance quadrature axis: 2.0 mπ― • PM flux: 6.2 mWb (measured with InstaSPIN) • Pole pairs: 50 Aim: • Sensorless (encoderless) FOC and speed control of a hybrid PM stepper motor using StEmbed and InstaSPIN • Stator resistance measurement prior to startup • Measurement of torque and shaft speed Duco W.J. Pulle 38 Hybrid stepper motor drive demo Introduction Motor concept: • Toothed rotor and stator • Axially oriented magnet between two toothed rotor sections • Rotor sections displaced by 1.8 degrees (200 steps) • Winding 1: consists of 4 pole ‘red’ windings • Winding 2: consists of 4 pole ‘black’ windings • Windings interconnected to form a two-phase machine with terminals A-B-C that are connected to a three-phase converter • ‘Micro-stepping’ type operation assumed with sinusoidal currents • Operation identical to a 50 pole pair salient two- phase synchronous PM machine A C Next : How to connect a 2-phase motor to a 3-phase converter B Duco W.J. Pulle 39 Hybrid stepper motor drive demo C2000 MCU + Tx Rx Serial coms (UART) Timers and PWM Compare Units SPI Serial coms Capture Unit ADC ADC channels shown here may not match those actually in use 2-phase Stepper Motor PWM1 PWM2 PWM3 PWM4 PWM5 PWM6 PWM1 SIMO SOMI CLK STE DC Bus PWM3 PWM5 CAP/QEP A ADCIN0 ADCIN1 ADCIN2 ADCIN3 ADCIN4 ADCIN5 ADCIN6 PWM2 PWM4 C PWM6 B Shunt resistor ADCIN2 Phase Voltage Meas ADCIN1 ADCIN3 Signal Conditioning Duco W.J. Pulle ADCIN4 ADCIN5 ADCIN6 40 Hybrid stepper motor drive demo How to connect a 2 phase motor to a three-phase converter Use of ‘2-phase’ space vector modulation : • inputs: m_alp (u1), m_beta (u2) • Outputs: m_a (u1c), m_b(u2c) and m_c (u3c) m_alp m_beta m_a m_b m_C SVM 2-ph module Micro-stepping example: • inputs: m_alp (red) , m_beta (blue) • Outputs: m_a (red), m_b (blue), and m_c (green) Duco W.J. Pulle 41 Hybrid stepper motor drive demo Overall representation of MCU based drive : Stepper_FAST_8312phCv2 • • Inputs to this module are: – per unit reference frequency freq_n, amplitudes: id_n, iq_n and speed slider gains: Kpn, Kin – 'speed_loop_on: activates FOC with speed control when ‘on’ and Torque control when ‘off’ – 'encoderless_on': uses angle estimate from FAST when 'on' and Current & frequency control when 'off' – 'Force_ang_on': activates 'zero speed start' when 'on' – 'conv _on' : activates converter – ‘Rs_Recal’: activates the Rs measurement algorithm at start up – 'chan_sel' : selects diagnostic channels to be viewed: ch1-2 or ch3-4 Outputs are: – Per unit, DC bus voltage, PM flux, shaft speed and torque – Two test variables : vr1, vr2 , that show the direct axis inductance and stator resistance values used by FAST – Ivec: vector current amplitude – Rs_Recal: the Rs value estimated prior to startup What does the 'controller' module look like internally ? Duco W.J. Pulle 42 Hybrid stepper motor drive demo One level down into the 'controller' Modules present are: • Dialog boxes: 'operation variables' and 'Converter/FAST variables' • Main motor control unit: triggered by the ADC conversion unit, running at 15 kHz • 100Hz unit: controls LEDS which show that MCU is operating and current trip on/off. Also executes all background task of the drive. • Diagnostic tool unit: used to look at 4 'test' signals real time , 2x2. User can place 'test' variables to desired locations within 'main motor control unit' to examine signals and set triggering. next: what is the content of the dialog boxes? Duco W.J. Pulle 43 Hybrid stepper motor drive demo Operational Variables Dialog box: motivation for entries shown • • • • • • • FullscaleVoltage(V)= 35: value chosen should be higher than highest bus voltage and less than twice the ADC full-scale voltage of 66.32 V (DRV8312EMV unit). FullscaleCurrent(A)=10: value higher than the highest expected current . Value should be less than twice the ADC full-scale current of 17.277 A (DRV8312EMV unit). FullscaleFrequency(Hz)= 400: value set by highest expected electrical frequency, which is determined by the largest expected shaft speed, typically the rated motor value. Max_Duty_cycle_CC= 0.8: maximum value for linear operation (with SVM active) is 1.15. Userfrequency Ramp(Hz/s)= 20000: value determines the rate of frequency change User Current Ramp(A/s)= 100: value determines the rate of current change for the slider inputs Rs_est_current(A)=0.5: current value used for stator resistance measurement prior to start-up Duco W.J. Pulle 44 Hybrid stepper motor drive demo Operational Variables Dialog box: motivation for entries shown (continued) • • • • • • Userfrequency Ramp(Hz/s)= 20000: value determines the rate of frequency change (and therefore speed change). With a full-scale frequency of 400 Hz , it would take πππ πππππ = ππ ππ to reach this value. User Current Ramp(A/s)= 100: value determines the rate of current change (and therefore torque change as the quadrature reference will be limited by this setting). With a full-scale current of 20 A , it would take ππ πππ = π. π π to reach this value. Current controller_Kp (V/A) =40: the upper limit gain is set by product of stator inductance and controller sampling frequency, hence 2.68 ππ― x 15 kHz=40.2 Typically a value in the order of 25% of the maximum value is used for entry. Current controller_wi (rad/s) =400: the upper limit bandwidth is set by ratio of stator resistance and stator inductance , hence π. πππ/π. ππ ππ―= 367.1 Speedcontroller_limit (A)=2.5: value set the quadrature current reference limit and therefore the shaft torque limit. Shaft torque is determined by π»ππ = π. π π© ππ ππ·π΄ , hence with ππ = π. π, PM flux ππ·π΄ =6.2 mWb, π = ππ the torque will be limited to ±π. ππ π΅π. Current trip (A) =8: value monitors the currents ππΆ , ππ· and trips the converter when the set value is exceeded. Duco W.J. Pulle 45 Hybrid stepper motor drive demo Converter and FAST Variables Dialog box: motivation for entries shown • • • Voltage_filter(Hz) =714.4: value chosen must match the corner frequency of the converter low-pass filters used to measure the voltages. The hardware corner frequency should typically should typically be chosen in a range set by the full-scale frequency value and the PWM frequency/10, hence 400-3000 Hz in this case. Speed filter pole(Hz) =50: corner frequency of a low-pass filter that filters the estimated shaft speed. Value should be chosen 5-10 times the bandwidth of the speed controller. Force_angle_freq (Hz)=0.8: The force-angle function assists with start-up and speeds up the synchronizing process between estimated EMF and actual machine EMF vectors Function must be turned off when speed reversals are required. Duco W.J. Pulle 46 Hybrid stepper motor drive demo Converter and FAST Variables Dialog box: motivation for entries shown(continued) • • • • • • • • • • • Direction pole (Hz)= 6: a low-pass filter that filters the estimated EMF waveforms to determine the rotational direction of the shaft Flux pole(Hz)= 100: a low-pass filter that filters the estimated flux. Flux_est_hold_freq (Hz)= 0.2: this sets a frequency band -0.2 to 0.2 where the estimator ‘freezes’ the estimated flux value. DC bus pole(Hz)=20: a low-pass filter that filters the measured per unit inverse DC bus voltage value π ππ«πͺ. ADC_offset pole (Hz)=1: a low-pass filter that is used to determine the ADC offsets. PWMFreq(Hz)=30000: PWM frequency required for the converter, set to 30kHz. Fsampling(Hz)=15000: Sampling frequency used by the current controller. The ratio between the PWM frequency and the Sampling frequency must be an integer value. Presently this is 2. Fest_Fsampling=1: variables set the sampling frequency used by the FAST estimator. With a value of 1 the estimator frequency is set equal to the current controller value, which is the preferred setting. In this case the estimator frequency will therefore be 15 kHz. Fspeed_Fsampling=15: variables set the sampling frequency used by the speed controller. With a value of 15 the sampling frequency is set to 1/15th of current controller value. In this case the speed controller frequency will be 1 kHz. Convergence factor=1.5: a factor which influence the time needed to synchronize the estimated EMF vector with the actual EMF vector. ADC_Fullscale _voltage(V)=66.32: value set by hardware (DRV8312EVM) . Duco W.J. Pulle 47 Hybrid stepper motor drive demo Converter and FAST Variables Dialog box: motivation for entries shown(continued) • • • • • • ADC_Fullscale _current(A)=17.277: value set by hardware (DRV8312EVM). Lq(H)= 2.0e-3: quadrature axis inductance value of the machine. Ld(H)= 2.68e-3: direct axis inductance value of the machine. It value can be found by using an L-C-R meter or estimated via InstaSPIN. Rs(Ohms)=0.984: Stator resistance of the machine. Its value can be found using the Rs recalibration routine prior to start up. PM_flux_est(Wb)=6.2e-3: the estimated PM flux value of the machine. p=50: pole pair number of the machine which is either known, or must be experimentally found. Duco W.J. Pulle 48 Hybrid stepper motor drive demo Overall representation of 'main motor control' module Modules present are: • 'Drive controller', in this case a d,q synchronous current controller, speed controller and FAST software encoder module • 'ADC-PWM unit', which measures the voltages from the shunt resistors, conv. phases and DC bus and controls the three half-bridges of the converter • ‘amp’ module that calculates the current vector amplitude • 'Current trip', which shuts down converter if absolute user set value is exceeded next: one level into the ‘Drive Controller' Duco W.J. Pulle 49 Hybrid stepper motor drive demo Implementation of the drive controller Details controller: • inputs: normalized reference frequency, current amplitudes and DC bus voltage as well as measured two-phase currents and filtered voltages. • outputs: modulation index, three-phase and FAST variables • 'C-Ramp' and 'FRamp' control rate of current and frequency change (user defined) • FAST software encoder module, set to operate at 15 kHz, and active when 'estimator' on line : state=3 • Rs_estimation module, estimates the Rs value FOC controller next: One level into the ADC-PWM modules Duco W.J. Pulle 50 Hybrid stepper motor drive demo Changes to the ADC-PWM module for two –phase drives Details : • inputs: m_a , m_b, m_c • Outputs: u_bus_n, u_alp_n, u_beta_n, i_alp_n and i_beta_n m_a m_b m_C u_bus_n u_alp_n u_beta_n i_alp_n i_beta_n not used ADC module next: C+ implementation ? Duco W.J. Pulle 51 Hybrid stepper motor drive demo Final step needed to achieve real time control: Stepper_FAST_8312phCv2_d We need a '-d' version of the previous simulation that can run the 'xxx.out' file Example per unit ππΆ , ππ· currents, with ‘hand applied’ load Duco W.J. Pulle 52 Model helicopter drive demo Introduction Experimental drive setup: • Texas Instruments DRV8301-HC unit with F2806x ISO control board • 11.1 V DC supply Li-Po Battery • Walkera V450BD5 model helicopter Motor parameters (measured with L-C-R meter, without motor lead) : • Stator resistance: 3.2 mπ • Stator inductance : 2.0 ππ― • PM flux: 0.55 mWb (measured with InstaSPIN) • Pole pairs: 3 Aim: • Sensorless (encoderless) FOC torque and speed control of the WKWS-28-007A PM motor using StEmbed and InstaSPIN • Stator resistance measurement prior to startup • Measurement of rotor torque and rotor blade speed Duco W.J. Pulle 53 Model helicopter drive demo Overall representation of MCU based drive : Heli_8301phCv7 • • Inputs to this module are: – per unit reference frequency freq_n, amplitudes: id_n, iq_n and speed slider gains: Kpn, Kin – 'speed_loop_on: activates FOC with speed control when ‘on’ and Torque control when ‘off’ – 'encoderless_on': uses angle estimate from FAST when 'on' and Current & frequency control when 'off' – 'Force_ang_on': activates 'zero speed start' when 'on' – 'conv _on' : activates converter – ‘Rs_Recal’: activates the Rs measurement algorithm at start up – 'chan_sel' : selects diagnostic channels to be viewed: ch1-2 or ch3-4 – ‘ext_spd_pot_on’: activates potentiometer on 8301 board for speed control Outputs are: – Per unit, DC bus voltage, PM flux, shaft speed and torque – Two test variables : vr1, vr2 , that show the direct axis inductance and stator resistance values used by FAST – Ivec: vector current amplitude, Rs_Recal: the Rs value estimated prior to start – Pot_sp_ref: the per unit shaft speed set by external speed potentiometer Duco W.J. Pulle 54 Model helicopter drive demo Final step needed to achieve real time control: Heli_8301phCv7_d We need a '-d' version of the previous simulation that can run the 'xxx.out' file Example per unit ππΆ , ππ· currents rotor blade torque (Nm) and speed (krpm) Duco W.J. Pulle 55 Model helicopter drive demo Current measurements: existing and new drive Use of Tektronix DC current probe to measure phase current under partial load (helicopter-ground operation) Standard drive Operation with InstaSPIN and FOC Example drive under speed control Duco W.J. Pulle 56
