Zhu Dongqi

Research of control system of permanent magnet brushless synchronous motor for EV

The paper describes an approach for the control strategy of permanent magnet synchronous motor (PMSM) used for electric vehicles (EV). The control strategy is to fulfil the special requirements of flexible control of torque and flux weakening control during high speed. Also the strategy can get large torque per stator current. Simulation results show that the proposed approach works well.

High power hybrid active power filter for medium-voltage distribution network

This paper proposes a novel hybrid active power filter (HAPF) for 6 kV/10 kV medium-voltage distribution network. Passive power filter (PPF) and a small-rated active power filter (APF) using diode neutral-point-clamped (NPC) three-level inverter, which is shunted to fundamental resonance circuit (FRC), are directly connected in series without any matching transformer, thus forming the shunt HAPF. Its principle and control strategies were discussed. In order to decrease the tracking error of harmonic compensation current and to improve dynamic response of the HAPF, a fuzzy proportional repetitive learning current control scheme was proposed, which consists of three control units: proportional control unit, repetitive control unit and fuzzy adjustor unit. Simulation and experiment results proved the feasibility and validity of the novel HAPF and its control scheme

Study of novel traction substation hybrid power quality compensator

In order to improve the power quality of the traction power supply system, a novel hybrid power quality compensator with new construction and new compensation method is proposed. The hybrid power quality compensator has the following features: (1) a three-phase voltage type converter is used in two-phase circuit of the traction power supply systems. The power quality of traction substation can be regulated integrally because the two feeders are linked indirectly; (2) through a Scott transformer, two banks of passive filters and the three-phase converter are connected in series so that the capacity of the converter is reduced greatly; (3) the compensating object is not one of the feeders but the traction substation itself; and (4) by regulating the active power currents in two feeders, the traction substation will reach a load balance status. So the reactive power, negative-sequence and harmonic currents in two feeders of a traction substation are canceled together. Its feasibility is proven by simulation results.

Control methods of hybrid active power filters reduced rating of its converter

This paper presents three control methods for a hybrid active power filter (HAPF), which is reduced the rating of active converter. Main circuit topology and their principles of the HAPF were discussed in detail. The single-phase equivalent circuits in harmonic domain of the HAPF are also given. Experiment waveforms were gotten from a laboratory prototype, rated at 10 kVA. Experiment results prove the active converter rating accounts for only 4.42% of the HAPF rating while the total harmonic distortion of the source current is reduced to 4.25% from 26.95% with the combined control method, which is better than the other control methods.

Fuzzy Proportional Repetitive Control for Current tracking of Hybrid Active Power Filter

This paper discussed the principle and filtering characteristics of hybrid active power filters (HAPF) using a combined control method. From the single-phase equivalent model of HAPF, a fast current tracking control is necessitated for harmonic compensation current and periodic disturbances. In order to decrease the tracking error and to improve dynamic response of HAPF, a fuzzy proportional repetitive controller was proposed based on internal model principle. The controller can also suppress non-periodic disturbances and has well adaptability in case of the severe fluctuation of the loads. The steady state and dynamic experiment waveforms were gotten in a laboratory prototype, rated at 10 kVA. Experiment results proved the feasibility and validity of the novel control strategies.

Ventilation structure research of 3-phase medium high voltage asynchronous machines

This paper studies the ventilation and heating of Y-series medium high voltage asynchronous machine with the method of air-way and heating-way. The study proves that axial ventilation structure should be adopted for medium high voltage asynchronous machines. Compared to the conventional structure, the improved machines not only save raw materials, but also improve manufacturing efficiency. The computer program for the calculation of the machines ventilation and temperature rise was made and real rest results show the validation of the improvements of the machines.