Kou Baoquan

Flux-Weakening-Characteristic Analysis of a New Permanent-Magnet Synchronous Motor Used for Electric Vehicles

The permanent-magnet (PM) synchronous motor (PMSM) takes advantages of small capacity, high efficiency, and high power density and have become commonplace in electric-vehicle driving systems. However, the excitation of PMSM cannot be adjusted, which restrains the PMSM from widening the speed range above its base speed. A PMSM with a variable magnetic reluctance field adjustment is presented in this paper. A new structure of the rotor is introduced, and flux-weakening (FW) principle is formulated. Analysis is discussed, including the force on the main PM, the movement process of the PM in the PM slot, the characteristics of the movement of the PM, and the FW performance of the new PMSM used for electric vehicles. The emulation analysis coincides with the test result, which verifies the availability and feasibility of the FW method for this kind of PMSM used for electric vehicles.

The Thrust Characteristics Investigation of Double-Side Plate Permanent Magnet Linear Synchronous Motor for EML

Electromagnetic launch (EML) system has such advantages as high thrust, good controllability, reusable, etc., and so it will be widely used in the future. As a launching motor, a double-side plate permanent magnet linear synchronous motor (PMLSM) can provide high instantaneous thrust. According to the characteristics of the EML, this paper studies the thrust characteristics of double-side plate PMLSM. Analyzes the thrust and thrust ripple characteristics in different conditions including: phase current, length of air-gap, height of secondary permanent magnet and pole arc efficient. The analysis results provide a foundation for the optimum design of electromagnetic launcher.

A new flux weakening method of permanent magnet synchronous machine

As traditional permanent magnet synchronous machines (PMSM) are deficient in flux weakening operation, a new method of automatic flux weakening with the rotor speed is presented. The flux weakening principle of permanent magnet synchronous motor (PMSM) is introduced. The flux weakening speed range is investigated and the forces on magnetic conductor which for adjusting the leakage reluctance of the rotor are analyzed in detail. Results from the finite element field emulation analysis are presented to verify the validity and feasibility.

Loss calculation and thermal simulation analysis of high-speed PM synchronous generators with rotor topology

The machine under study is a high speed permanent magnet (PM) synchronous generator, which is driven by a micro gas turbine, whose rated power is 117 kW at 60 000 rpm. Magnetic field distributions in generators having either semi-closed slots or closed slots are analyzed respectively when PM is magnetized by two different familiar magnetizing methods, and eddy losses in each rotor are calculated. Then, influence of copper screen on eddy loss distribution is studied, and the relationship between thickness of copper screen and loss is discussed as well. Finally, based on loss calculation, thermal performances of generators with different rotor structures mentioned above are studied, and utility of copper screen in improving temperature rise issue is demonstrated.

Research on Electromagnetic Force of Large Thrust Force PMLSM Used in Space Electromagnetic Launcher

A large thrust force permanent magnet linear synchronous motor that is used in a space electromagnetic launcher is designed. We study the thrust force and the normal force by taking some practical elements into account, including yoke thickness of primary and secondary cores, thickness and width of permanent magnet, air gap length, slot width, and turns of coils. We present an optimized design methodology for the maximum thrust force. The thermal analysis is verified by simulation and test. Also, the test result turns out to fall into correspondence with the theoretical analysis. It then would demonstrate the advantage of our method over some existing ones.

Torque characteristics of double-stator hybrid stepping motor with serial magnetic circuit structure

This paper presents a project for double-stator hybrid stepping motor with serial magnetic circuit structure. After analyzing the electromagnetic torque characteristics via linear analytics and testing the prototype, the result demonstrates that the ratio of torque to volume is higher in this kind of motor. If the motors electromagnetic parameters and structural parameters are designed rationally, not only there will be an increase to the motors torque output, but also the motors rotational inertia will decrease, both starting frequency and running frequency accordingly improve.

The research on energy regeneration of permanent magnet synchronous motor used for hybrid electric vehicle

As permanent magnet synchronous motor (PMSM) has the characteristics of high power density, high efficiency, and high torque current units, so it is extensively used in electric vehicles driving. Energy management unit (EMU) in hybrid electric vehicle (HEV) demands for good motor driving and energy regeneration capability. Based on the mathematical model of PMSM, this paper presents the PMSM vector control algorithm, studies HEV energy regeneration requirements for motors and analyzes power generation work mechanism of PMSM. At last, combined with HEV control strategy, simulation of PMSM system energy regeneration research is done and the simulation results show that the system has good performance.

The principle and design of the permanent magnet bias DC reactor

In this paper, the authors present the principle of the permanent magnet bias DC reactor, examine the linear resolution and design of its magnet circuit, and detail experiments carried out on the reactor.

Research on interpolar leakage coefficient of PMSM with variable magnetic reluctance in the exciting circuit

Permanent magnet synchronous motor (PMSM) driving system used in electric vehicles get a lot of development in recent years. A PMSM with variable magnetic reluctance in the exciting circuit by the movable permanent magnet in permanent-magnet slot is presented. Flux weakening is accomplished by reduction of effective magnetic flux area provided by permanent magnets duo to the variable magnetic reluctance. The special rotor structure and flux weakening principle are introduced. No-load interpolar leakage coefficient is link to the usage of permanent magnets, demagnetization ability and flux weakening speed range. While flux weakening of this new PMSM doesnpsilat lie in demagnetization armature reaction and the no-load interpolar leakage coefficient design method is different from the general PMSM. From four aspects of air-gap length, magnetic bridge size, permanent magnets size and motion to research on the no-load interpolar leakage coefficient. Calculation result is corresponding with analysis and laid the foundation on the design and analysis of this new PMSM.

Research on rotating encoder zero-position location based on missile steering gear

Permanent magnet synchronous motor (PMSM) is applied to aerospace missile steering gear as the structure of servo position with excellent performance of small volume, precision and reliability. For reducing error of actuator, it is important that initial position of actuator should keep consistent with rotorpsilas initial position because the dynamic key parameters of servo system are influenced by rotor position. Therefore, it is a key point that actuatorpsilas zero position and rotating encoder rotorpsilas should be coincident. In this paper, rotating encoder is applied to position sensor in missile steering gear servo system for testing rotor position, and the method of confirming initial position is advanced, then the method which keeps actuatorpsilas zero position and rotating encoder rotorpsilas being coincident is advanced. The better control effect is attained by combining space vector control strategy.