Yaohua Li

Research on Tractive Characteristics of the Single Linear Induction Motor

The SLIM has been widely applied in transportation for its simple-firm structure and its directly forward electromagnetic thrust. The motor has transverse and longitudinal end-effects because of its discontinuous magnetic circuit. There are eddy currents, which become greater as motor speed increases, occurring in both entrance and exit of its secondary sheet. End effects and eddy currents bring ill impact to air gap magnetic flux, which reduce its available magnetic flux and pull coefficient. This paper works out the d-q axis equivalent circuits of SLIM considering end effects. The changes of mutual inductance and resistance in d-axis indicate both the second longitudinal end effect and the eddy current influences. Then the article establishes SLIM math equations connected with the rotor-flux oriented (RFO) vector control theory. This paper brings forward uds, uqs, iqs online decouple compensation basing on the rotor magnetic flux, speed, current regulators, which adjust and accommodate tractive force, d-q axis voltages, d-q magnetic fluxes, d-axis mutual inductance. The simulation and experimental results indicate that this method is reasonable, which provides theory guidance to the SLIM application analysis and achieves some active effects.

Implementation of Sensorless Control with improved flux integrator for Wound Field Synchronous Motor

In this paper, a sensorless control with improved flux integrator for wound field synchronous motor is presented. This paper analyses the wound field synchronous motors mathematical model. The stator flux can be accurately estimated based on the improved flux integrator with feedback compensator. With the estimated flux and only the q-axis inductance, the position is accurately estimated which is critical for field oriented vector control. The experimental results show that the proposed sensorless algorithm is reliable in a wide speed range above 1Hz.

A novel fast current-control method for the back-to-back converters

This paper presents a novel fast current-control method for the back-to-back converter. In this paper, two methods which are used to produce the reference value during the dynamic period are introduced in order to get fast dynamic response. Simulation and experiment show the feasibility and the conspicuous advantage of the methods.

Study and design considerations of three-phase bi-directional AC/DC converter

By now, three-phase bi-directional AC/DC converter has been developed to an advanced level with the property of high efficiency, high power quality, low cost, enhanced reliability. This paper makes a detailed review of three-phase bi-directional AC/DC converters, and explores a broad perspective on different topologies and control schemes to designers, application engineers and end users. At last, this paper presents some design considerations, which saves time and cost of development for designers and bring about great convenience for end users and engineers.

Investigation of topologies for IGCT three-level inverter

The integrated gate-commutated thyristor (IGCT) is a new device with low inductance and integrated gate-driver which is widely used in high power inverter. This paper presents the principle of IGCT clamping snubber, investigates several topologies with different turn-on clamping snubber for NPC three-level IGCT inverter and compares inverter topology with turn-off snubber to topology without turn-off snubber by a PSIM simulation. A high power NPC three-level inverter equipped with 4.5 kV/4 kA IGCT devices is implemented. The experiments of single IGCT device and three phase system demonstrate that both the power circuit and control system are designed reasonable and valid. The implementation inverter can be widely used in high power adjustable drive system.