Extended Virtual Signal Injection Control for MTPA Operation of IPMSM Drives With Online Derivative Term Estimation

According to the recent study, most of the mathematical model based motor efficiency optimized control schemes ignore the derivative terms of machine parameters with respect to the current angle. Therefore, even though the accurate machine parameters are known, these control schemes cannot calculate the accurate efficiency optimized operation points. Due to the machine parameter nonlinearity and harmonics, these derivative terms are difficult to be obtained online, which cause great difficulties in achieving accurate maximum torque per ampere (MTPA) control. To solve the above issues, in this article, an extended virtual signal injection control scheme is proposed. The proposed control scheme can automatically compensate for the MTPA control errors caused by parameter variations and achieve accurate MTPA control online. The proposed control method is demonstrated by both simulations and experiments under various operating conditions on prototype interior permanent magnet synchronous machine drive systems.