Electric vehicle charger load current harmonics variations due to supply voltage level differences — Case examples

Modern switching power converters responsible for AC to DC conversion use advanced control methods that guarantee close to unity power factor and sine-like current waveforms. The level of harmonic distortions of such converters that employ power factor correction (PFC) can be rather low and remain in ranges of few percent. Such converters are employed also as chargers as electric vehicles (EVs). When EVs are connected to the low-voltage grid for slow charging, the AC supply voltage levels of the different charging locations are likely to vary. This can also provide effect to the load current waveform distortions, affecting the magnitude and phase shift angles of the individual harmonics. In this paper a discussion is presented on the effects of the AC supply voltage variations to the load current harmonic patterns and summation of harmonic currents when the chargers are used at different AC voltage levels.