Research On Sensorless Control Strategies For Sic Based Pmsm Drives

In recent years,permanent magnet synchronous motors(PMSMs)have received wide attention due to their advantages of high efficiency and high power density.In addition,with the development of Silicon Carbide(SiC)power semiconductor devices,their application prospects in the field of motor drive are receiving more and more attention.However,their high switching frequency and high power density characteristics put forward higher requirements on the structure of the driver and the performance of the control chip.From the perspective of system cost and reliability,mechanical sensors have certain drawbacks.Therefore,position sensorless control technologies are still a hot research topic.SiC-based PMSM driver platform has been built and based on it,the sensorless control strategies which have been researched in this paper was verified through experiments.Firstly,a rotor initial position detection strategy based on random high-frequency square-wave voltage injection is researched.The initial position and polarity information can be obtained only by the high-frequency current and the large-amplitude pulse signal is not needed in this method.Under the condition of ensuring the identification accuracy,the proposed initial position identification process is more continuous.With the high-frequency noise reducing,the vibration and noise are eliminated effectively.Next,for the high-frequency noise problem caused by high-frequency signal injection,a zero-and low-speed sensorless control strategy for PMSM based on PWM carrier component information is researched.This method does not need to inject additional voltage or current signals,and only uses the zero-vector interval current derivative to estimate the rotor position,which can fundamentally eliminate the high-frequency noise.By using the dual-core driver platform ?-? oversampling technology and the least squares method,the current and current derivative can be obtained more accurately,and the sensorless control performance can be improved.Further,a medium-and high-speed sensorless control strategy based on full-order sliding mode observer is studied.Based on the extended back EMF model of PMSM,a full-order sliding mode observer with stator current and extended back EMF as state variables is established to improve the system control performance and robustness.A sensorless control simulation model based o n full-order sliding mode observer is established to verify the effectiveness of the control strategy.Finally,the SiC-based PMSM driver platform is built.The high-frequency square-wave voltage injection method,the sensorless control algorithm based on PWM carrier component information and the full-order sliding mode observer method are all verified on this platform.The experimental results prove the correctness of the dual-core driver platform construction.Further,they also prove that the platform can quickly and accurately obtain the zero-vector interval current derivative and improve the rotor position estimation accuracy.In addition,the full-speed position sensorless stable operation of PMSM has already been realized on this platform.