Soft-Switching Current-Fed Push–Pull Converter for 250-W AC Module Applications


In this paper, a soft-switching single-inductor push– pull converter is planned. A push–pull converter is sufficient for low-voltage photovoltaic ac part systems, because the step-up ratio of the high-density motor is high, and the number of primary-side change is almost small.


However, the conventional push–pull converter does not have high ability because of high-change losses due to hard change and transformer losses (copper and iron losses) as a result of the high turn ratio of the motor.


In the planned converter, primary-side switches are turned ON at the zero-voltage change condition and turned OFF at the zero-current change condition through parallel resonance between the secondary leakage inductance of the motor and a resonant capacitor.


The planned push–pull converter decreases the change loss using soft change of the primary switches.In addition, the turn ratio of the motor can be reduced by half using a voltage-doubler of secondary side. The theoretical analysis of the planned converter is verified by simulation and experimental results.


  1. Current-fed push–pull converter
  2. Photovoltaic (PV) ac module
  3. Soft-switching



Fig. 1. Control block diagram of the dc–dc converter and dc–ac inverter using a microcontroller.


Fig. 2. (a) Carriers and a reference for PWM. (b) Waveforms of primary

switch S1 . (c) Waveforms of primary switch S2 .

Fig. 3. (a) Boost inductor current iLbst . (b) Resonant capacitor voltage vC r .

 Fig. 4. (a) Waveforms of tracking the MPP. (b) PWM according to MPPT. (c) Start flag of MPPT.

Fig. 5. Current and voltage waveforms of switch S1 according to ZVS and ZCS.

Fig. 6. Waveforms of resonant capacitor voltage and boost inductor current.


In this paper, the soft-change single-inductor push–pull converter for PV ac module applications is planned. Soft change was accepted at each part, and MPPT is achieve for obtain the maximum power from the PV module.


change of the primary side operate in the ZVS condition at turn-off and in the ZCS condition at turn-on. The planned converter maintains a Vo of 400 V to provide ac 220 Vrms for dc–ac inverters. The maximum ability is 96.6%. These results were accepted by simulation and verified by a 250-W experimental setup.


[1] S. B. Kjaer, J. K. Pedersen, and F. Blaabjerg, “A review of single-phase grid-connected inverters for photovoltaic modules,” IEEE Trans. Ind. Appl., vol. 41, no. 5, pp. 1292–1306, Sep. 2005.

[2] S. B. Kjaer, J. K. Pedersen, and F. Blaabjerg, “Power inverter topologies for photovoltaic modules: A review,” in Proc. IEEE. Ind. Appl. Conf., vol. 2, Oct. 2002, pp. 782–788.

[3] Y. Xue, L. Chang, S. B. Kjaer, J. Bordonau, and T. Shimizu, “Topologies of single-phase inverters for small distributed power generators: An overview,” IEEE Trans. Power Electron., vol. 19, no. 5, pp. 1305–1314, Sep. 2004.

[4] R. Gonzalez, J. Lopez, P. Sanchis, and L. Marroyo, “Transformerless inverter for single-phase photovoltaic systems,” IEEE. Trans. Power Electron., vol. 22, no. 2, pp. 693–697, Mar. 2007.

[5] T. Shimizu,K.Wada, andN.Nakamura, “Flyback-type single-phase utility interactive inverter with power pulsation decoupling on the DC input for an AC photovoltaic module system,” IEEE Trans. Power Electron.,, vol. 21, no. 5, pp. 1264–1272, Sep. 2006.

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