永磁电机模型参考自适应控制

Abstract- Traditional
PI
contrຫໍສະໝຸດ Baiduller
has
received
a
wide
application for its simple structure and reliability. However, its proportion and integration parameter generally cannot be set too large to avoid overshoot. This restriction leads to degradation of dynamic performance, which is not expected in high-performance servo system. Therefore, searching for new control strategies at is a same trend time to to improve prevent the dynamic of the performance controlled the appearance achieve
Research on Predictive Control for PMSM based on Online Parameter Identification
Wang Weihua, Xiao Xi
Dept. of Electrical Engineering, Tsinghua University, China E-mail: xiaoroupang@163.com reliable structure, so has received a wide range of applications. However, it is difficult taking these two aspects of the fast response and no overshooting into account simultaneously, which makes it almost impossible to further significantly improve its dynamic performance. Hysteresis control strategy tries to keep the controlled system variables between the boundaries of a hysteresis area or space [2l. The simplest form of this principle is the so­ called "bang-bang controller", which has a advantage of simple concept and very rapid response, at the cost of large ripple and variable switching frequency. There is also a similar "chattering" problem in sliding mode variable structure control strategy, which makes them unsuitable to be applied in high-performance control applications. It is worth noting the method mentioned in Ref. [3], which is a method named "double sample and double updating (DSDU)". Theoretically, it can decrease the control delay by half and double the dynamic response speed. However, it is at the cost of doubling the computation of current loop and also depends on the special design of the hardware. If the DSP PWM module cannot be updated twice in one sampling period, this method cannot be realized at all. Predictive control is a promising control method, which requires the precise mathematical model of the controlled object [4l. It is prospective to reach the smallest control delay and achieve the fastest response without large overshoot. However, the predictive control strategy relies heavily on an available accurate mathematical model of the controlled object, which is often difficult or unable to obtain. In this paper, the method of model reference adaptive system is employed for online parameter identification of permanent magnet synchronous motor parameters such as stator resistance, dq axis inductance and the permanent magnet flux so as to obtain an accurate mathematical model of the controlled object. On this basis, the predictive control strategy is then adopted to improve the dynamic performance of the permanent magnet synchronous motor current. Simulation and experimental results show that the MRAS­ based online parameters identification method obtains the accurate model of permanent magnet synchronous motor, which eliminates the impact of parameter errors on the effect of predictive control. The application of predictive control strategy greatly accelerates the current dynamic response, proving the effectiveness of the proposed program.
I.
INTRODUCTION
Permanent magnet synchronous motors (PMSM) are receiving increased attention for high-performance servo applications because of their high torque to inertia ratio, superior power density, and high efficiency [ll. In these applications, fast dynamic response is pursued to improve quality and efficiency. So it is expected to enhance the dynamic performance of the electromagnetic torque. In other words, more rapid control of the dq axis current is expected to achieve because there is a direct relationship between them and the electromagnetic torque. At present, the controlling methods of the permanent magnet synchronous motor current loop include traditional PI regulator, hysteresis control, sliding mode variable structure control, predictive control, and so on. The traditional PI regulator is independent of the mathematical model of the controlled object, and has a characteristic of simple and
overshoot. Predictive control strategy, which is based on the object mathematical model, can theoretically fastest dynamic response. However, there is an inherent defect that it relies on the accurate mathematical model of the controlled object, which is usually difficult to obtain. Specific to high-performance servo system, real-time change of parameters of servo motor may occur, coupled with some non­ ideal characteristics. All these factors restrict the predictive control strategy to play its best function. Aiming to improve the dynamic performance of permanent magnet synchronous motor servo system, this paper presents a predictive current control strategy based on on-line parameter identification of PMSM. Model reference adaptive system (MRAS) is employed to identify the parameters of PMSM. Based on the recognition results, predictive control strategy is adopted to control the dq axis current of the permanent magnet synchronous motor. In this way, the interference of parameter error is eliminated and perfect dynamic performance of the current loop is expected. Simulation and experimental results show that the predictive control method proposed here achieves very excellent dynamic response system. without overshoot. In addition, the automatic recognition of parameters leads to good robustness of the whole