Xinhua Guo

The smooth transition research of different PWM modulations for vector control of induction motor in medium voltage high power

In high power AC speed regulation systems, frequency of inverter is wide and frequency of switching is limited. In this paper, the PWM strategy for vector control of induction motor in medium voltage high power is introduced. Asynchronous modulation and multi-step synchronous modulations are concluded in the PWM strategy. In synchronous modulations, selective harmonic elimination PWM (SHEPWM) is employed because of low switching frequency. The factors impacting smooth transition between different PWM modulation modes are analyzed. The corresponding solutions are put forward. And these methods are verified by some experiments in induction motor with 135kW.

Vector control of induction motor based on selective harmonic elimination PWM in medium voltage high power propulsion system

With the demands of the propulsion systems, medium voltage high power AC drives are required. In high power AC drives, the switch frequency of the devices has to be limited in order to reduce the loss of the power semiconductor devices, torque ripple and electromagnetic interference. In this paper, a proposed drive control system with selective harmonic elimination PWM (SHEPWM) for induction motor is presented. Designed control is based on rotor-field oriented vector control of induction motor with employed PWM strategy which holds four different modulations. SHEPWM principle is introduced. The results of simulations are presented to verify the feasibility of control method in medium voltage high power system (1.6MW). And the correctness of this proposed control system is verified by experimental results in a small-scale laboratory prototype.

PI parameter design of the flux weakening control for PMSM based on small signal and transfer function

In this paper, the transfer function of PMSM drives system with feed forward complete decoupling is developed based on the small signal model. According to the transfer function, the stable operation range of system and PI parameter of flux weakening control are analyzed by Routh Stability Criterion. According to the analysis results, the stable operation range of system is to reduce with the speed increasing when PI parameter of flux weakening control keeps invariant, and the system even becomes unstable. So the PI Parameter of flux weakening control should be designed to increase the stable operation range to keep the system stable. What is more, the system is always stable in some areas, and the PI parameter designed in this area just affect the dynamic performance of system, which is validated by experiment.

Solutions and experimental verification of bipolar selected harmonics elimination PWM waveforms Applied in control system of induction machine

Selected harmonics elimination PWM (SHEPWM) strategy adopted in railway driving system promises to have better performance than other PWM strategies, such as SVPWM and SPWM. However, since SHEPWM was proposed, the calculation of switching-angle curves has been a hot research point. Up to now, many approaches have been applied and multiple solutions of SHE equations have been obtained. This paper presents a combinational approach based on mathematical software toolboxes, which is fast and convenient for engineering applications. Detailed explanation of calculating switching-angle curves is listed. Another undocumented set of switching-angle curves for N=4 is shown to confirm the proposed approachs effectiveness. Finally, certain switching-angle curves below 60 are picked for simulation and experiments, which are both based on closed-loop vector control system of induction machines. Results prove that harmonics selected are eliminated effectively.

Application of PM type DMPM in hybrid electric vehicle

This paper presents a new full hybrid system with a PM type DMPM using a new mechanism in the decoupling of the internal combustion engine (ICE) optimal working points and the power train output shaft operation points. In this paper, the working points of this system are explained. The comparison of system efficiencies is made. The results suggest that the system proposed can obtain the same or even higher efficiency than that of Toyota Hybrid System using high speed planetary gear set. The torque coupling and decoupling of the inner and outer motors of DMPM during the steady and start-stop transient states are analyzed. A control scheme is proposed. The research results are used to drive a 38kW/52kW PM type DMPM system loaded on a SUV of about 2700kg. The maximum speed of the SUV reaches 122.5km/h.

Dead-time compensation of SVPWM based on DSP TMS320F2812 for PMSM

The dead-time effect in a three-phase voltage source inverter can result in voltage losses, current waveform distortion and torque pulsation. In order to improve the current waveform and decrease the torque pulsation, this paper proposes a dead-time compensation method of SVPWM. This method divides the iα - iβ plane into six sectors and compensates the dead-time of SVPWM according to the sector number of stator current vector determined by the α - and β -axis components of the stator current vector in the two-phase static reference frame. In addition, this method can be implemented entirely through software without any extra hardware. Finally experiments based on DSP TMS320F2812 are established and made, and the experiment results indicate that the proposed method is correct and feasible.

Analysis and experimental verification for multiple solutions of bipolar SHEPWM waveforms applied in control system of induction machines

Since selective harmonic elimination PWM (SHEPWM) was proposed, the calculation of switching-angle curves has been a hot research point. Up to now, many approaches have been applied and multiple solutions of SHE equations have been obtained. Multiple sets of switching-angle curves provide SHEPWM strategies, which are often adopted in the control system of induction machines for railway driving, more options. This paper aims to analyze harmonic characteristics of multiple solutions and shows experimental results to verify their difference.