Integrated charger for electric vehicles

What is it about?

Power converters present key parts in vehicle powertrain. An electric vehicle’s powertrain system usually consists of a three-phase motor inverter, a battery and an electric motor. Additional unit (charger) is used to charge the onboard batteries. Integrated charger is obtained by a transformation of a conventional three-phase inverter, which is already present in an electric vehicle’s powertrain system in to the battery charger.

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Why is it important?

A major problem for the integrated charger proposed in the paper originates in the fact that the maximum battery voltage is commonly below the amplitude of the grid voltage. For this reason, the battery charger has to increase or lower the voltage depending on the instantaneous value of the grid voltage. The transitions between operation (increase/lower the voltage) may result in oscillations, discontinuities and distortion of the charger’s input current. In order to prevent such unwanted behavior a current control strategy is proposed that ensures smooth transitions between the two operating modes.