针对永磁同步电机的无位置传感器的磁场定向控制，采用了一种基于方波电压的脉振高频注入法。该方法注入新颖的方波电压信号，通过二阶有限长单位冲激响应(FIR)高通滤波器提取高频响应，使用闭环的锁相环进行位置计算，通过改变d轴基波电流辨别初始的转子极性。通过理论分析，用数学表达式描述了各环节实用的特征，然后根据分析的特征，进行了相应的试验。结果表明，注入高频方波，其频率提升至控制频率的一半，可闻噪声基本消失，信号处理极大简化，可测转速范围提升至中高速阶段。

For sensorless field oriented control of permanent magnet synchronous motor, a method of fluctuating high frequency square wave injection is used. Novel square wave voltage signal is injected by this method. High frequency response is extracted through a second-order finite impulse response (FIR) high pass filter. Rotor position is estimated by a closed-loop phase locking loop. The initial rotor polarity is distinguished by changing the current of d axis. Practical features of the control are expressed by formulas through theoretical analysis. Experiments are done according to the features. When the square wave is injected, the frequency of the wave can increase to one half of the control frequency and audible noise will basically disappear. Meanwhile, signal processing is enormously simplified, and the measurable range of rotation speed is improved to medium and high speed.