Harmonic Optimization Strategy of Aviation Multi-unit PMSM Generation System Based on Improved Carrier Phase Shift Modulation Method

In recent years, redundant multi-unit generator has garnered increasing attention in aviation power generation systems due to their high reliability. PWM-based rectifier control strategies generate sideband harmonic voltage excitation, which leads to harmonic currents that can degrade both rectifier efficiency and overall generator performance. Considering the mutual inductance coupling characteristics between different branches, this paper investigates the optimization problem of high-frequency sideband harmonic current control in a four-unit generator system for aviation application. The traditional 2π/N carrier phase shift modulation method, when applied to a multi-unit generator system with mutual inductance coupling, tends to increase the sideband harmonic content in the phase currents, which negatively impacting system performance. To address the limitations of the traditional carrier phase shift modulation method, this paper proposes a harmonic-optimization-based carrier phase shift angle optimization method. This method optimizes the sideband harmonic performance of a four-unit generator system by carefully selecting the appropriate carrier phase shift angles, taking into account the coupled inductance characteristics. The proposed optimization approach is effective for both normal and suboptimal operating conditions of the four-unit generator system. Finally, experimental validation of the proposed method is performed using a prototype of the four-unit generator system.