Multi-Virtual Signal Injection for Maximum Torque Per Ampere Control of Interior PMSM Considering Magnetic Saturation

The target of the maximum torque per ampere (MTPA) control is to detect the optimal angle of the interior permanent magnet synchronous motor (IPMSM), which can optimize the objective in terms of maximized output torque for the given magnitude of the stator current. This paper presents a MTPA angle detection method using multi-virtual signal injection, in which four virtual signals are injected into the machine to mathematically construct four virtual torques. The MTPA objective is then derived from the virtual torques for optimally detect the MTPA angle. Moreover, a polynomial based saturation model is employed to model and compensate the machine inductance variations in the virtual torque computation. In comparison to conventional virtual signal injection approaches, the proposed approach can achieve MTPA angle detection without filters and consider nonlinear inductance variation to improve the detection performance. The effectiveness of the developed method is tested with various experiments as well as the comparisons on the interior PMSMs.