Abstract

This paper proposes a newly developed hybrid current-mode control (HCMC) method for phase-shifted full-bridge (PSFB) converters. Generally, PSFB converters have been widely used in various DC-DC power applications owing to their ease of control and low switching losses. However, the transformer can be saturated by volt-second imbalance of the magnetizing inductance. Therefore, a blocking capacitor can be used in series with the transformer, or peak current-mode control methods with slope compensation can be applied, to prevent transformer saturation. However, blocking capacitors increase the material cost and make the power stage bulky. Moreover, the overcompensation by slope compensation methods delays the control response. This paper proposes a hybrid current-mode control (HCMC) for PSFB converters to solve these problems. A blocking capacitor and slope compensation are not required in the proposed HCMC method for PSFB converters. The proposed HCMC method has no transformer saturation and output response delay, and the efficacy of this method has been verified through simulations and experiments.

Highlights

  • Electric vehicles have attracted increasing attention owing to the worldwide depletion of fossil fuels and increasing environmental pollution [1,2,3]

  • A phase-shifted full-bridge (PSFB) converter with hybrid current-mode control (HCMC) was proposed in this paper to prevent current imbalance and compensate for an ineffective duty ratio

  • With PSFB converters, implementing double-loop voltage control using secondary-side current detection may generate a current imbalance that results in transformer saturation

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Summary

Introduction

Electric vehicles have attracted increasing attention owing to the worldwide depletion of fossil fuels and increasing environmental pollution [1,2,3]. PSFB converters experience transformer saturation due to the primary-side current imbalance [13,14]. Adding a blocking capacitor increases the size of the power stage and overall cost [15,16,17] Another method to prevent transformer saturation is peak current-mode control (PCMC). HCMC implements peak and valley current controls according to the input and output voltages and switching frequency to enable fast-response capability. This prevents the overcompensation-related response delay that typically occurs due to the operating slope compensation in the peak current mode.

Primary-Side Current Imbalance of PSFB Converters
Blocking Capacitor
Peak Current-Mode Control with Slope Compensation
Proposed Hybrid Current-Mode Control of PSFB Converters
Hybrid Current-Mode Control of Boost Converter
Hybrid Current-Mode Control for PSFB Converters
Simulation Result
Digital Code Initialization for Experiment
Conclusions
Full Text
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