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Single-phase power conversion such as PWM rectifier, grid connected PV inverter system, static synchronous compensator ( STATCOM ) all can be implemented by an H-bridge inverter and a large electrolytic dc capacitor to absorb the ripple power pulsating at twice the line frequency (2ω ripple power). This paper proposed a dc capacitor-less inverter for H-bridge with minimum voltage and current stress. By adding another phase leg to control an ac capacitor, the 2ω ripple power can be absorbed by the capacitor and theoretically 2ω ripples to the dc capacitor can be eliminated completely. The H-bridge and the addition phase leg can be analyzed together as an unbalanced three phase system. By adopting SVPWM control and choosing the optimum ac capacitance and the voltage reference, the voltage and current stress of the switches can be minimized to the same as the conventional H-bridge. The size of capacitor is reduced by 10 times compared to the conventional H-bridge system. Simulation and experimental results are shown to prove the effectiveness of the proposed dc capacitor-less inverter and active power decoupling method.PR controller parameters are as follows: k p =8, k r =11,  c =25, and the bode plot is shown in Fig. 8 (b).Accordingly, the transfer function from ac capacitor current reference to ac capacitor current is:0885-8993 (c)

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No abstract

Single-phase PWM rectifier, grid connected PV inverter system, static synchronous compensator (STATCOM) all can be implemented by an H-bridge inverter and a large electrolytic dc capacitor to absorb the ripple power pulsating at twice the line frequency (2ω ripple power). This paper proposed a generalized active power decoupling method for Hbridge with minimum voltage and current stress. By adding another phase leg to control an ac capacitor, the 2ω ripple power can be absorbed by the capacitor and theoretically 2ω ripples to the dc capacitor can be eliminated completely. The H-bridge and the addition phase leg can be analyzed together as an unbalanced three phase system. By adopting SVPWM control and choosing the optimum ac capacitance and the capacitor voltage reference, the voltage and current stress of the switches can be minimized to the same as the conventional H-bridge. The size of capacitor is reduced by 10 times compared to the conventional H-bridge system. Simulation and experimental results are shown to prove the effectiveness of the proposed active power decoupling method.

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No abstract

A new solid state variable capacitor (SSVC) with minimum dc capacitance is proposed. A variable ac capacitor (with capacitance variable from 0 to C ac ) is traditionally implemented by an H-bridge inverter and a large electrolytic dc capacitor with capacitance of 20 times the ac capacitance value, C ac to absorb the 2ω dc ripple. The proposed SSVC consists of an H-bridge and an additional phase leg connected to an ac capacitor with fixed capacitance, C ac and can reduce the dc capacitance to the minimum just for absorbing switching ripples. The fixed ac capacitor controlled by the additional phase leg absorbs the 2ω component and theoretically can eliminate 2ω ripples to the dc capacitor completely. Therefore, no electrolytic capacitors would be needed. Theoretical analysis of the SSVC is provided. Simulation and experimental results are shown to prove the effectiveness of the proposed SSVC with minimum dc capacitance.