Motor current reference generation for reducing motor currents in drive systems with single-phase diode rectifier and small dc-link capacitor

In this paper, new method for generating motor current references is proposed in motor drive systems with single-phase diode rectifier and small dc-link capacitor in order to reduce the amount of the motor currents. Unlike the conventional large dc-link capacitor, small dc-link capacitor cannot work as an energy buffer. Therefore the motor currents, d and q-axis currents in synchronous reference frame, as well as output power are pulsating. The previous studies for generating motor current references in small dc-link capacitor systems did not consider the derivation terms of current in voltage equation. This paper presents new motor current reference generation algorithm considering the derivation terms so that the current can be saved where the dc-link voltage is enough and on-line calculation of current references can be possible. With the proposed method, the level of the motor current is reduced compared to the previous one and the efficiency of the system increases consequently. The effectiveness of the proposed method was verified with the simulation results.