On influence of various modulation schemes on a PMSM within an electric Vehicle

A drive train system (DTS) powered by an ideal voltage source and driving a permanent magnet synchronous motor (PMSM) is discussed in this paper. A two-level, three-phase conventional inverter with no harmonic filters on both AC and DC sides is used as means of power conditioning. This DTS is modelled as a double oscillator according to a drive train in an electric vehicle. Various inverter modulation schemes are applied, namely, a single phase hysteresis scheme, a space vector based hysteresis scheme with a non rotating hysteresis shape as well as flux oriented hysteresis shape and modulation schemes based on pulse width modulation (PWM) such as sinusoidal modulation (including zero sequence components) and space vector pulse width modulation. The hysteresis based pulsing methods are non-deterministic and build a current controller in their structure by nature. The PWM related pulsing methods are deterministic due to their fixed switching frequency and need a separate control unit. The influence of these modulation schemes on the performance of the DTS is determined by assessing the level of inverter generated harmonics flowing to the PMSM and the resulting switching frequency (electrical part) and to the tyres (downforce, (mechanical part)). The simulated results presented in the paper indicate that the pulsing frequency can be reduced by means of the hysteresis controller and that with related dispersion of the harmonic energy of the inverter generated spectrum the absence of filters can be partly retained.