Li Tiecai

Accurate tracking control of a limited angle torque motor

The paper presents a limited angle torque motor used in optical scanning system. A method called repetitive control, in which the controlled variables follow periodic reference commands, is proposed to design the limited angle torque motor tracking control system. The compensator in the repetitive control system is synthesized by H/sub /spl infin// optimal control design theory. Experimental results show that the tracking performance of the repetitive controller is superior to that of the conventional controller.

Position-measuring error analysis and solution of hall sensor in pseudo-sensorless PMSM driving system

Referring to a PMSM (permanent magnet synchronous motor) driving system with only two low-cost hall sensors, this paper analyses the position-measuring error in one pseudo-sensorless scheme, and offers methods of error compensation. Adopting the methodology based on 3-d finite element analysis, this paper evaluates and practically locates the mounted positions of hall sensor in the PMSM to minimize the position-measuring error. Finally, experiments are carried out to verify the corresponding 3-d finite element analysis results.

A low cost drive strategy for BLDC motor with low torque ripples

Although brushless DC motors are widely used in industry drives, they cannot substitute the position of the permanent magnet synchronous motors in the high- performance applications due to the relatively high torque ripple. In this paper, three different single current sensor techniques are analyzed and compared. In order to minimize the pulsating torque, this paper presents a low cost BLDCM drive system, which adds only a current sensor and PID controller compared to the conventional drive system. The experimental results show this system has lower torque ripples, compared to the conventional driving method. This is helpful for finding wider application range of BLDCM.

A research on the radial unbalanced force in the unsymmetrical brushless PM motors

The brushless PM motors with concentrated windings have some common advantages such as the reduction of copper volume in the end-windings and low cost. Among these motors, some brushless PM motors with special unsymmetrical structures have particular advantages including high winding coefficient and low cogging torque. Those common advantages and particular advantages make the unsymmetrical brushless PM motors with concentrated windings suitable for drive system with high performance demand. However, there is a radial unbalanced force in this kind of motor due to their unsymmetrical structures. In this paper, the radial unbalanced force is studied using FEM through two motor models which have unsymmetrical structures. It can be seen from the simulation results that this unbalanced force exists under both sinusoidal and trapezoidal drive current. This force may cause acoustic noise in operation. Corresponding considerations should be given when applying this type of motors.

A 3-D Electromagnetic Thermal Coupled Analysis of Permanent Magnet Brushless DC Motor

In recent years, with permanent magnetic materials and motor manufacturing technique progressing, permanent magnet brushless DC motor power density enhances unceasingly. This means that the electromagnetic loads of the motor are continuously increasing, and the heat load is soaring. The motor thermal design is becoming more and more important. The thermal design is a complex problem of electromagnetic field and thermal field coupled. This paper proposes a new method of electromagnetic and thermal coupling analysis by calculating both the electromagnetic field and temperature field in motor. Simulation results and test data verify the rationality of the motor temperature field model and the accuracy of the calculation. Furthermore, the motor temperature field is analyzed at different ambient temperature and different ambient air velocity based on the method. This new analysis method proposed would be helpful for the optimization design of the motor.

The controlling system of the DC brushless servo motor of the locked position circle

This paper is intended to introduce the position DC brushless servo motor system used in the camera system of small satellites. The controller is based on DSP, and adopts AD2S82 as its axis-angle converter. Having the characteristics of a concise structure and an advanced control strategy, the research model can run steadily at low speed and locate positions accurately, thus coming up to the practical standards of the satellite camera system.

A standard development platform for motor controller based on DSP

This article, based on the embedded DSP, using reusable model hardware, describes a standard developing platform for motor controlling. An object-oriented software development method is transplanted into the hardware development of motor control. This method, through writing application subroutines, implements various kinds of standard control and algorithm, and constructs software resources. By connecting several of these application subroutines, development of a specific motor controller can be fast and easy.