Active DC-link circuit for single-phase diode rectifier system with small capacitance

This paper introduces the multifunctional circuit which is called as active DC-link circuit (ADLC) in single-phase diode rectifier system without electrolytic capacitor. This circuit is located to DC-link node in parallel and shows many performances such as energy buffer for decoupling ripple power and power factor correction (PFC) by controlling instantaneous system power. Therefore the diode rectifier system with ADLC does not need to equip additional PFC for satisfying grid regulations. Furthermore, since the ADLC can boost the DC-link voltage and supply the energy to the motor drive system while the DC-link voltage is lower than back electromotive force (EMF) voltage of motor, the drive system features constant torque and does not need excessive motor current for flux-weakening control in comparison with the conventional small capacitance motor drive system. This paper presents such a power control method and offers the design guideline of active DC-link circuit. The feasibility of the active DC-link circuit are verified by simulation results.