基于PWM控制的开关磁阻电机中低速无位置传感器控制方法

Sensorless control of switched reluctance motor at low and medium speeds based on PWM control

无位置传感器的中低速运行控制是开关磁阻电机研究的难点问题。为实现中低速阶段对转子位置的连续估计,提出一种基于PWM控制的无位置传感器方法。该方法将开通关断角所对应的参考信号与高频三角载波进行交截,并将得到的PWM信号作为不对称半桥功率变换器的开关管驱动信号。通过对PWM信号进行频谱分析可知,该PWM注入方式等效于注入载波频率的高频正弦信号。然后,对电流信号进行滤波及坐标变换处理,解算出连续的转子位置信息。针对电感曲线正弦度不高的问题,通过移相相减的方法消除二次谐波,简化了位置估计过程。该方法无需额外注入高频正弦信号,易于工程实现,并具备高频信号注入法的精度。最后针对一台12/8结构样机,进行了相应的仿真和实验,验证了该方法的可行性。

Sensorless control at low and medium speeds is still a challenging problem for switched reluctance motors. In order to estimate the rotor position continuously, a sensorless method based on PWM control is proposed. High-frequency triangle carrier waves intersect with low-frequency reference signals, which correspond to the rotor position. And the resultant PWM signals are used to drive the switching transistors of asymmetric half bridge converter. Spectral analysis shows that it is equivalent to inject sinusoidal signals with the same frequency as carrier waves. Then, after filtering and coordinate transformation, continuous rotor position information can be obtained. For the bad quality of sinusoidal inductance curve, phase shift and subtraction are applied to remove second harmonics, thus simplifying the process of estimation. Without injecting extra high-frequency signals, the method possesses the same accuracy and is easy for implementation. Finally, simulations and experiments are conducted on a 12/8 prototype to verify the validity of this method.