A novel method based on pulse-voltage-injection for compensation of gain errors of current measurements in iPMSMs for EVs

In this paper a new algorithm regarding compensation of gain errors of current measurements for 3-phase interior permanent-magnet synchronous machines (iPMSMs) is introduced. As a core feature of the method, a periodic square-wave (pulse) voltage superimposed with the fundamental commanded voltage is fed to the e-machine, the resulting current response to the injected voltage pulses is extracted from current measurements and used as the indicator of current measurement gain errors. Once mistuned gains are detected, they can be rescaled adaptively by the proposed control scheme. This algorithm shows reliable compensation within a large speed range, i.e., from standstill until high speed operation of the e-machine. Besides, it is a pure software-based solution, which can be implemented for sensing system with two- or three-sensor-based current measurement. Additionally it demands no electric parameters of iPMSMs if only balancing of gains between phases is considered. In general, this method can be launched during an initial commissioning, or as a part of start-up sequence, or periodically during the normal operation of the machine in Electric Vehicles (EVs).