MTPA Control for IPMSM Drives Based on Pseudorandom Frequency-Switching Sinusoidal Signal Injection

Among various maximum torque per ampere (MTPA) control schemes for interior permanent magnet synchronous motor (IPMSM) drives, the signal-injection-based methods exhibit relatively high overall performance due to their high control accuracy and satisfactory dynamic performance. However, the high current spectrum peaks induced by the fixed-frequency signal injection may cause electromagnetic interference and even audible noise problems in applications, such as electric vehicles, vessels, and aircraft. To address this problem, an MTPA control method using pseudorandom frequency-switching sinusoidal signal injection is proposed in this paper. The sinusoidal signals with two different frequencies are randomly injected into the d- and q-axis currents and the MTPA points can be tracked according to the resultant system response. In this way, a high-performance MTPA control can be achieved regardless of motor parameter variations. Since the injection frequency of the proposed method varies randomly, the induced harmonic components in phase currents no longer concentrate at certain frequencies, and the current spectrum peaks caused by signal injection can be reduced accordingly. The experimental results demonstrate the validity of the presented method.