恒定导通时间双频率控制开关变换器

Study of Constant On-Time Bi-Frequency Control Technique for Switching Converters

本文提出并研究了一种新型开关变换器控制技术——恒定导通时间双频率(COT-BF)控制技术。COT-BF控制技术利用两组预先设定的具有相同导通时间但不同开关频率的控制脉冲,实现对开关变换器输出电压的调整。COT-BF控制器实现简单,无需误差放大器及其相应的补偿网络。本文以电感电流断续导电模式(DCM)Buck变换器为例,研究了COT-BF控制开关变换器的工作原理及控制策略,并进行了实验研究。实验研究结果表明,COT-BF控制DCM Buck变换器具有比传统电压型脉冲宽度调制开关变换器更快的瞬态响应速度和更低的电磁干扰。

A novel control technique,constant on-time bi-frequency（COT-BF） control technique,for switching converters is proposed and investigated in this paper.The proposed COT-BF control technique regulates output voltage of switching converters by two preset control pulses with constant on-time but different switching frequencies.The COT-BF controller is easy to be realized without error amplifier and its corresponding compensation network.The principle and control strategy of COT-BF are analyzed with a Buck converter operating in discontinuous conduction mode（DCM） as an example.Experimental results show that COT-BF controlled DCM Buck converter has much faster transient response and lower EMI than that with conventional voltage-mode pulse width modulation（PWM） technique.