Design And Implementation Of Position Sensorless FOC Algorithm For Permanent Magnet Synchronous Motor

Permanent magnet synchronous motor(PMSM)is not complicated in construction and has good output characteristics.Therefore,it is used in a lot of areas.The design of the PMSM control system has recently gained more attention both in the academia as well as industry.The field-oriented control(FOC)system controls the PMSM as a DC motor.Therefore,the FOC systems are often used to control PMSM.The FOC system measures the position information of the rotor using a mechanical sensor which has high cost and limited performance.In this research,a Sensorless approach to detect of position information of the rotor is adopted to solve the problem.A sensorless FOC algorithm is designed to measure the rotor position in PMSM.The modular design method is adapted to the design of the control system.Each module is designed and analyzed separately and then all the modules are integrated into FOC control system.To decouple the effect of strong coupling characteristics in PMSM coordinate transformation module is designed.Moreover,space vector pulse width modulation(SVPWM)module is designed to control the inverter output similar sinusoidal AC requirements.The coordinate transformation module converts the three-phase AC of the PMSM into two-phase DC,and makes the two DC vectors orthogonal to each other.One of the two DC components is a torque current,and the other is an exciting current,for any current.The control does not affect the va lue of the other current.The space vector pulse width modulation module also improves the voltage utilization efficiency on the DC side while satisfying the inverter to produce a similar sinusoidal AC.The space vector pulse width modulation module generates a PWM wave according to a combination of six basic voltage vectors and two zero vectors.in time.Then the PWM wave control the switching state of the six IGBT tubes of the inverter,thereby generating a six-step staircase wave similar to sinusoidal AC.A sliding mode observer method is proposed to measure the position of the rotor in the FOC control system.A continuous saturation function is used to weaken the chattering phenomenon which is inherent in the sliding mode observer method instead of using the symbol function.Moreover,Using mathematical model of PMSM in synchronous rotating coordinate system to estimate Back EMF.While extracting the rotor position,arctangent function in the traditional sliding mode observer generates more error.Therefore,phase-locked loop is used instead of the arctangent function to extract the position information of the rotor.In order to verify the performance of the improved FOC system,the schematic diagram of the FOC system is designed,and the traditional FOC system with the sliding mode observer and the improved FOC system are simulated and analyz ed.It is observed that the improved FOC system outperforms the traditional FOC system with the sliding mode observer.Then the STM32F103 development board is used to implement the improved FOC system.The experiments show that the improved FOC control system has good control performance for the motor running at medium and high speeds.