Automatic MTPA Control for IPMSM Drives Based on Pseudorandomly Reversed Fixed-Frequency Sinusoidal Signal Injection

Signal-injection-based methods are a kind of competitive maximum torque per ampere (MTPA) control schemes for interior permanent magnet synchronous motor drives, due to their motor parameter independence and satisfactory control performance. However, the high current spectrum peaks (CSPs) produced by the conventional fixed-frequency injected signals may cause negative effects. To deal with this problem, an MTPA control method based on pseudorandomly reversed fixed-frequency (PRRFF) sinusoidal signal injection is proposed in this article. The PRRFF sinusoidal signals are injected into the
d
- and
q
-axis currents via a specific current loop, and the MTPA operating points can be detected utilizing the resultant system response. Benefiting from the random characteristic of the injected signals, the proposed method can achieve far lower injection-induced CSPs than the conventional fixed-frequency injection methods. Moreover, benefiting from the fixed-frequency characteristic of the injected signals, the proposed method avoids the difficult matching of candidate injection frequencies that exists in the pseudorandom-frequency injection method. The validity of the proposed method is confirmed by experiments.