Wide-Range ZVS Phase-Shift Full-Bridge Converter With Reduced Conduction Loss Caused by Circulating Current

Abstract:In this paper, a load adaptive control method to improve the efficiency and dynamic performance of the Phase-Shifted Full-Bridge (PSFB) converter which works under a wide range of load conditions is presented. The proposed control method can be used as a battery charger since this application demands a wide range of load conditions. The composition of the PSFB converter's losses and the loss analysis model are both discussed. According to this model, the optimum switching frequency which results in minimum power loss is adopted to improve the efficiency. The relationship between switching frequency and power loss is formulated over a wide load range. Indicated by this kind of relationship, the proposed controller adjusts the switching frequency at different load currents. Moreover, an adaptive gain adjustment controller is applied to replace the traditional controller, with the aim to improve the dynamic performance which is influenced by the changes of the switching frequency and load current. In addition, the experimental results show that the maximum improvement of efficiency is up to 20%. These results confirm the effectiveness of the proposed load adaptive control method.

“…The core losses can be calculated using the Steinmetz Equation (1). This equation has proven to be an effective method for the calculation of the magnetic core power losses.…”

Section: Magnetic Core Lossesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

High Efficiency Variable-Frequency Full-Bridge Converter with a Load Adaptive Control Method Based on the Loss Model

Zhao

Liu

et al. 2015

“…For the sake of minimizing the size of the resonant inductor used to store sufficient energy for the lagging leg of the inverter bridge to achieve ZVS under a light load condition, many different improvement methods have been proposed, for example, a combined phase-shift control algorithm and frequency modulation was proposed to achieve ZVS over the full load range in [16]; new control methods [17][18][19][20] were used for the converters under a light load condition to improve efficiency; a converter containing two paralleled half-bridge inverters and an auxiliary inductor on the primary side is proposed [21], which allows the stored energy for ZVS operation to change adaptively with duty-cycle and thus reduces the output filter inductance; phase-shift control with an L-C-L filter could also be utilized for ZVS to improve the performance [22]; DC link voltage was adjusted dynamically by power factor correction (PFC) in order to relieve the stress on semiconductor switches and improve the converter efficiency [23]; a two-stage isolated bi-directional DC-DC converter was investigated [24] which could enlarge the ZVS region by interleaving the converter with supercapacitors; dead-time for the lagging leg of the inverter bridge was adjusted predictively to assist the switches to perform ZVS at light load [25]; two additional switches were connected in parallel with the lagging leg of the inverter bridge to reduce switching loss under light load [26,27]; a novel ZCS-ZVS power factor correction PFC converter was proposed [28] with an efficiency of higher than 97%; two additional low-current diodes were added to the center-tap of a transformer secondary to improve ZVS at light load [29]; some other researchers proposed different control methods [30,31] and accomplished ZCS for the lagging leg, while retaining ZVS for the leading leg [31]. Improved ZVS techniques for the active switches of the forward converter are also adopted [32] in order to reduce switching and conducting losses to deal with PV power and wind energy.…”

Section: Introductionmentioning

confidence: 99%

A New Control Method for a Bi-Directional Phase-Shift-Controlled DC-DC Converter with an Extended Load Range

Chan

et al. 2017

Phase-shifted converters are practically important to provide high conversion efficiencies through soft-switching techniques. However, the limitation on a resonant inductor current in the converters often leads to a non-fulfillment of the requirement of minimum load current. This paper presents a new power electronics control technique to enable the dual features of bi-directional power flow and an extended load range for soft-switching in phase-shift-controlled DC-DC converters. The proposed technique utilizes two identical full bridge converters and inverters in conjunction with a new control logic for gate-driving signals to facilitate both Zero Current Switching (ZCS) and Zero Voltage Switching (ZVS) in a single phase-shift-controlled DC-DC converter. The additional ZCS is designed for light load conditions at which the minimum load current cannot be attained. The bi-directional phase-shift-controlled DC-DC converter can implement the function of synchronous rectification. Its fast dynamic response allows for quick energy recovery during the regenerative braking of traction systems in electrified trains.

“…The loss of ZVS results in high Electromagnetic Interference (EMI) and low efficiency due to the increase of switching loss. The methods proposed in [10][11][12][13] can extend the ZVS range by adding auxiliary circuits which provide enough energies to achieve complete ZVS for all switches. Several methods to improve the efficiency of PSFB converter have been proposed, especially under light load conditions, with no additional devices.…”

Section: Introductionmentioning

confidence: 99%

A Novel Choice Procedure of Magnetic Component Values for Phase Shifted Full Bridge Converters with a Variable Dead-Time Control Method

Zhao

et al. 2015

Magnetic components are important parts of the phase shifted full bridge (PSFB) converter. During the dead-time of switches located in the same leg, the converter can achieve zero-voltage-switching (ZVS) by using the energies stored in magnetic components to discharge or charge the output capacitances of switches. Dead-time is usually calculated under a given set of pre-defined load condition which results in that the available energies are insufficient and ZVS capability is lost at light loads. In this paper, the PSFB converter is controlled by variable dead-time method and thus full advantage can be taken of the energies stored in magnetic components. Considering that dead-time has a great effect on ZVS, the relationship between available energies and magnetic component values is formulated by analyzing the equivalent circuits during dead-time intervals. Magnetic component values are chosen based on such relationship. The proposed choice procedure can make the available energies greater than the required energies for ZVS operation over a wide range of load conditions. Moreover, the burst mode control is adopted in order to reduce the standby power loss. Experimental results coincide with the theoretical analysis. The proposed method is a simple and practical solution to extend the ZVS range.