Analysis and compensation of the rotor position offset error and time delay in field-oriented-controlled PMSM drives

In high-performance field-oriented control of permanent magnet synchronous machines (PMSMs), an accurate rotor position is indispensable for the key roles in coordinate transformations. However, due to the rotor position offset error and the time delay in digital control systems, it is still challenging to obtain exact rotor position information. In this study, the influence of rotor position error on the control performance of a PMSM drive system is analysed first. Then, two novel compensation technologies, i d regulation and i q = 0 methods, are proposed to accurately compensate for the rotor position for both current and voltage coordinate transformations. The advantage of the proposed scheme is that even without any prior knowledge of the system delay, the rotor position offset and compensation time coefficients can also be precisely calculated. Parameter sensitivity analysis is carried out, and compensation criteria are also provided to improve the compensation accuracy. Experimental results on a 300 kW PMSM drive system demonstrate that compared to the results achieved with conventional methods, the compensation accuracies of the phase angles used for the current and voltage coordinate transformations are increased by 6 ° and 3.1 ° at 5000 r/min, respectively. Consequently, the control performance and stability margin of the system are efficiently improved.