Nonlinear Loss Optimization Control of Permanent Magnet Synchronous Motor Direct Drive System
Reducing the loss of the permanent magnet synchronous motor drive system is of great significance to the performance improvement of pure electric vehicles. Based on the analysis of the traditional linear loss model, this paper constructs a new nonlinear loss model for the operating characteristics of permanent magnet synchronous motor, which can accurately estimate the system loss in any working condition range. Based on the new nonlinear system loss model, this paper proposes the nonlinear loss comprehensive optimization control of the permanent magnet synchronous motor drive system, and achieves the overall optimization of system efficiency through the optimal matching of motor loss and driver loss. The experimental results show that compared with the traditional maximum torque-to-current ratio control, the nonlinear loss comprehensive optimization control can effectively improve the loss characteristics of the system under the full working condition, improve the energy utilization rate of the motor drive system, and achieve energy-saving purposes.
1 Introduction
As the main power source of pure electric vehicles, the operating efficiency of permanent magnet synchronous motor drive system will directly affect the cruising range of electric vehicles under one charge, which will seriously affect the application range of electric vehicles [1-2]. In order to improve the direct drive system of permanent magnet synchronous motor, for the complexity of the operating conditions of electric vehicles, a variety of efficiency optimization control strategies have been applied to the efficiency improvement of permanent magnet synchronous motor drive system, and good results have been achieved. According to the dynamic mathematical model of the motor, the literature [3-4] proposed the maximum torque-to-current ratio control method. By adjusting the stator magnetic field of the motor, the permanent magnet synchronous motor has the minimum stator current when the output torque is constant, thus reducing the motor loss. It has the advantages of fast speed and easy implementation. In [5-7], an efficiency optimization control strategy based on permanent magnet synchronous motor loss model is proposed. The accurate loss model of the motor is constructed according to the copper loss and iron loss of the motor, and the speed and current of the permanent magnet synchronous motor are detected or estimated in real time. The signal, based on the loss model of the motor, derives the optimum flux value at the highest motor efficiency. Literature [8] proposed an efficiency optimization control strategy based on online search technology for minimum input power. This method does not require the accurate loss mathematical model of permanent magnet synchronous motor, and searches for the optimal current online by detecting the input power of the system to realize the motor drive system. Efficiency optimization.
Although the minimum power control strategy has the advantages of slow response and strong adaptability to parameter changes, its optimization time is too long, which is difficult to meet the application requirements of complex electric vehicle application complex conditions, and the energy saving effect is not satisfactory. However, the traditional loss-based model of the permanent magnet synchronous motor efficiency optimization control is difficult to construct an accurate driver loss model, and can only optimize the efficiency of the motor loss, so that the optimal system efficiency can not be optimized. Therefore, in order to meet the needs of high-efficiency drive control of permanent magnet synchronous motor direct drive system under complex conditions, this paper proposes a permanent magnet synchronous motor direct drive system based on nonlinear system loss model for complex operating conditions of pure electric vehicles. Nonlinear loss comprehensive optimization control. The non-linear polynomial is used to accurately fit the nonlinear conduction characteristics and switching characteristics of the power components, so as to accurately estimate the driver losses under different operating conditions. On this basis, the nonlinear loss model of the permanent magnet synchronous motor direct drive system in the whole working condition is constructed by analyzing the copper loss and iron loss characteristics of the permanent magnet synchronous motor. Based on the system loss model, the relationship between the stator current of the motor and the optimal loss of the system is studied by using the optimization theory. The optimal distribution of motor loss and driver loss is realized by the nonlinear loss comprehensive optimization control, which effectively improves the range of permanent magnets in the whole working condition range. Loss characteristics of synchronous motor direct drive systems. The proposed loss comprehensive optimization control is verified on the designed permanent magnet synchronous motor experimental platform. The experimental results show that compared with the traditional maximum torque current ratio control, the nonlinear loss comprehensive optimization control can effectively improve the full working range. The permanent magnet synchronous motor directly drives the efficiency characteristics and energy utilization of the system, thereby achieving the purpose of improving the cruising range of the pure electric vehicle.
2 permanent magnet synchronous motor direct drive system loss model
In order to realize the optimal loss control of the nonlinear loss of the permanent magnet synchronous motor direct drive system, it is necessary to construct a precise system loss model of the permanent magnet synchronous motor drive system. The loss of the permanent magnet synchronous motor drive system is mainly composed of two parts: permanent magnet synchronous motor loss and driver loss. The motor loss mainly includes the copper loss of the motor and the iron loss of the motor, and the driver loss mainly includes the conduction loss of the power device and the switching loss of the power device.
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