LCC谐振变换器非对称移相控制及效率优化方法

提出一种LCC谐振变换器的非对称移相控制方法。该方法采用PWM移相混合调制方式,有两个控制变量,实现了更高的控制自由度。分析LCC谐振变换器的稳态特性,包括输出功率特性、软开关特性以及谐振电流特性。分析结果表明,不同的控制变量组合能够实现同一输出功率,但会导致软开关及谐振电流特性发生变化。在此基础上提出一种效率优化策略,使谐振变换器在输出功率不变的情况下谐振电流降至最低,同时保证了软开关的实现。所提出的方法能够进一步提升LCC谐振变换器的效率。通过仿真及1.9k W样机验证了理论分析及所提控制方法的可行性和有效性。

Asymmetrical Phase Shift Control and Efficiency Optimization Strategy for LCC Resonant Converter

In this paper,an asymmetrical phase-shift (APS) control for the series-parallel (LCC-type) resonant converter was proposed.A pulse width modulation (PWM) and phase-shift combined modulation scheme was implemented to achieve two independent control variables,which introduced additional degrees of freedom in control.The steady-state characteristics of the converter were analyzed including output power,zero-voltage switching (ZVS) operation and resonant current.This analysis demonstrates that different combinations of duty cycle and phase shift angle can achieve the same output power,leading to distinct root mean square (RMS) resonant currents and affecting ZVS operation.An efficiency optimization strategy based APS control was then proposed to deliver a specific output power with minimized RMS resonant current while maintain ZVS.As such,the efficiency of the converter is improved in a wide load variation range.The theoretical analysis and the validity of the proposed method has been verified by the results of simulation and a 1.9kW prototype.