Suppression of DC-Link Voltage Fluctuation in Electric Turbocharger System

Abstract

In electric turbocharger systems, in which the permanent magnet synchronous motor (PMSM) is driven by the power generated by the permanent magnet synchronous generator (PMSG) connected to the internal combustion engine to assist the drive power of the compressor, it is required to reduce the capacitance of the DC-link capacitor between the PWM rectifier and the inverter. However, if a DC-link capacitor with small capacitance is used, the DC-link voltage fluctuates in transient conditions such as when the engine speed fluctuates. Therefore, this study investigates the suppression control of the DC-link voltage in the transient state. In addition, an experimental system with a diesel engine and an electric turbocharger is constructed. Using this experimental system with an 870µF film capacitor, the DC-link voltage fluctuation could be suppressed by maximum of 17.5 and 16.5 points during turbine acceleration and deceleration, respectively. This was achieved by feed-forward control of the generator-side current. The results revealed that the DC-link voltage fluctuation could be suppressed by a maximum of 17.5 points during turbine acceleration and 16.5 points during turbine deceleration.