Department of Electrical Engineering Southern Taiwan University of Science and Technology Robot and Servo Drive Lab. 2015/7/2 Digital Control Strategy for Four Quadrant Operation of Three Phase BLDC Motor With Load Variations Professor: MING-SHYAN WANG Student: WEI-CHIN FANG C. Sheeba Joice, S. R. Paranjothi, and V. Jawahar Senthil Kumar IEEE TRANSACTIONS ON INDUSTRIAL INFORMATICS, VOL. 9, NO. 2, MAY 2013 p

Department of Electrical Engineering Southern Taiwan University of Science and Technology Outline FOUR QUADRANT OPERATION OF BLDC MOTOR BLDC Motor Four Quadrant Operation DIGITAL CONTROLLER PI Controller PWM Module ADC Module COMPLETE DRIVE SYSTEM SIMULINK MODEL PRACTICAL IMPLEMENTATION RESULTS CONCLUSION REFERENCES 2015/7/2 Robot and Servo Drive Lab. 2

Department of Electrical Engineering Southern Taiwan University of Science and Technology Abstract This paper deals with the digital control of three phase BLDC motor. The motor is controlled in all the four quadrants without any loss of power; in fact energy is conserved during the regenerative period. 2015/7/2 Robot and Servo Drive Lab. 3

Department of Electrical Engineering Southern Taiwan University of Science and Technology BLDC Motor 2015/7/2 Robot and Servo Drive Lab. 4 Fig. 1. BLDC Motor Star connected. The numbers shown around the peripheral of the motor diagram in Fig. 1 represent the sensor position code.

Department of Electrical Engineering Southern Taiwan University of Science and Technology BLDC Motor The rotor position decoder has six outputs which control the upper and lower phase leg MOSFETs of Fig /7/2 Robot and Servo Drive Lab. 5 Fig. 2. Equivalent Circuit of power stage of BLDC motor.

Department of Electrical Engineering Southern Taiwan University of Science and Technology Four Quadrant Operation There are four possible modes or quadrants of operation using a Brushless DC Motor which is depicted in Fig /7/2 Robot and Servo Drive Lab. 6 Fig. 3. Four Quadrants of operation.

Department of Electrical Engineering Southern Taiwan University of Science and Technology Four Quadrant Operation When BLDC motor (Fig. 4) is operating in the first and third quadrant, the supplied voltage is greater than the back emf which is forward motoring and reverse motoring modes respectively, but the direction of current flow differs. 2015/7/2 Robot and Servo Drive Lab. 7 Fig. 4. Operating Modes.

Department of Electrical Engineering Southern Taiwan University of Science and Technology PI Controller The regulation of speed is accomplished with PI Controller. By increasing the proportional gain of the speed controller, the controller’s sensitivity is increased to have faster reaction for small speed regulation errors. This allows a better initial tracking of the speed reference by a faster reaction of the current reference issued by the speed controller. This increased sensitivity also reduces the speed overshooting. 2015/7/2 Robot and Servo Drive Lab. 8

Department of Electrical Engineering Southern Taiwan University of Science and Technology PWM Module The PWM module simplifies the task of generating multiple synchronized Pulse Width Modulated (PWM) outputs. It has six PWMI/O pins with three duty cycle generators. For each duty cycle, there is a duty cycle register that will be accessible by the user while the second duty cycle register holds the actual compared value used in the present PWM period. 2015/7/2 Robot and Servo Drive Lab. 9

Department of Electrical Engineering Southern Taiwan University of Science and Technology ADC Module The 10 bit high speed analog to digital converter (A/D) allows conversion of an analog input signal to a 10 bit digital number. This module is based on Successive Approximation Register (SAR) architecture, and provides a maximum sampling rate of 500 ksps. The timer registers are used to store the duty cycle of the PWM pulses that are generated. In the Hall sensor mode, the input capture module is set for capture on every edge, rising and falling, The interrupt on Capture mode setting bits,,is ignored, since every capture generates an interrupt. The output compare module generates an interrupt to trigger the relay circuit during regenerative mode. 2015/7/2 Robot and Servo Drive Lab. 10

Department of Electrical Engineering Southern Taiwan University of Science and Technology COMPLETE DRIVE SYSTEM Four quadrant Zero current transition converter (4Q—ZCT) was implemented for DC motor and single controllable switch for four quadrant operation was implemented for SRM drive. The common regenerative braking methods include adding an extra converter, or adding an extra ultra-capacitor, or switching sequence change of power switches. Relay circuits are employed to run the motor during the accelerating mode and charge the battery during the regenerative mode. 2015/7/2 Robot and Servo Drive Lab. 11

Department of Electrical Engineering Southern Taiwan University of Science and Technology COMPLETE DRIVE SYSTEM The schematic diagram of the drive arrangement of the three phase BLDC motor is shown in Fig /7/2 Robot and Servo Drive Lab. 12 Fig. 5. Closed Loop Drive.

Department of Electrical Engineering Southern Taiwan University of Science and Technology COMPLETE DRIVE SYSTEM Whenever there is a reversal of direction of rotation it implies there is a change in the quadrant. 2015/7/2 Robot and Servo Drive Lab. 13 Fig. 6. Relay Circuit.

Department of Electrical Engineering Southern Taiwan University of Science and Technology SIMULINK MODEL 2015/7/2 Robot and Servo Drive Lab. 14 Fig. 7. Simulink Model of Four Quadrant Drive.

Department of Electrical Engineering Southern Taiwan University of Science and Technology SIMULINK MODEL 2015/7/2 Robot and Servo Drive Lab. 15 The model of the controller shown in Fig. 8, receives the Hall signals as its input, converts it in to appropriate voltage signals. Fig. 8. Modeling of Controller.

Department of Electrical Engineering Southern Taiwan University of Science and Technology SIMULINK MODEL 2015/7/2 Robot and Servo Drive Lab. 16 Fig. 9. Output of Simulink model—Rotor speed(rpm), Stator current (A), Stator back emf (V).

Department of Electrical Engineering Southern Taiwan University of Science and Technology SIMULINK MODEL 2015/7/2 Robot and Servo Drive Lab. 17 Fig. 10. Reference Speed and Actual Speed in rpm.

Department of Electrical Engineering Southern Taiwan University of Science and Technology PRACTICAL IMPLEMENTATION 2015/7/2 Robot and Servo Drive Lab. 18

Department of Electrical Engineering Southern Taiwan University of Science and Technology PRACTICAL IMPLEMENTATION 2015/7/2 Robot and Servo Drive Lab. 19 Fig. 12. Flowchart for four quadrant controller.

Department of Electrical Engineering Southern Taiwan University of Science and Technology RESULTS 2015/7/2 Robot and Servo Drive Lab. 20 Fig. 13. Hall Sensor signals and Phase Current.

Department of Electrical Engineering Southern Taiwan University of Science and Technology RESULTS 2015/7/2 Robot and Servo Drive Lab. 21 Fig. 14. Trapezoidal Voltages of RY and YB.

Department of Electrical Engineering Southern Taiwan University of Science and Technology RESULTS 2015/7/2 Robot and Servo Drive Lab. 22 Fig. 15. PWM Pulses—Control signals to the Inverter.

Department of Electrical Engineering Southern Taiwan University of Science and Technology RESULTS 2015/7/2 Robot and Servo Drive Lab. 23 Fig. 16. Quadrant transition.

Department of Electrical Engineering Southern Taiwan University of Science and Technology RESULTS 2015/7/2 Robot and Servo Drive Lab. 24 Fig. 17. Speed Control with load of 0.5 kg.

Department of Electrical Engineering Southern Taiwan University of Science and Technology RESULTS 2015/7/2 Robot and Servo Drive Lab. 25 Fig. 18. Energization with no load.

Department of Electrical Engineering Southern Taiwan University of Science and Technology RESULTS 2015/7/2 Robot and Servo Drive Lab. 26 Fig. 19. Energization with a load of 0.5 kg. Fig. 20. Energization with a load of 1 kg.

Department of Electrical Engineering Southern Taiwan University of Science and Technology RESULTS 2015/7/2 Robot and Servo Drive Lab. 27 Fig. 21. Energization of the Battery.

Department of Electrical Engineering Southern Taiwan University of Science and Technology CONCLUSION The significant advantages of the proposed work are: simple hardware circuit, reliability of the control algorithm, excellent speed control, smooth transition between the quadrants and efficient conservation of energy is achieved with and without load conditions. 2015/7/2 Robot and Servo Drive Lab. 28

Department of Electrical Engineering Southern Taiwan University of Science and Technology REFERENCES [1] C. S. Joice, Dr. S. R. Paranjothi, and Dr. V. J. S. Kumar, “Practical implementation of four quadrant operation of three phase Brushless DC motor using dsPIC,” in Proc. IConRAEeCE 2011, 2011, pp. 91–94, IEEE. [2] T. W. Ching, “Four-Quadrant Zero-Current-Transition Converter-Fed Dc Motor Drives for Electric Propulsion,” Journal of Asian Electric Vehicle Vol. 4 (2006) No. 2 P /7/2 Robot and Servo Drive Lab. 29