单周控制Buck变换器中的降频现象分析

研究了单周控制Buck变换器中的降频现象，并给出了降频现象发生的临界条件以及电感电流断续导电模式(DCM)与电感电流连续导电模式(CCM)的临界条件.研究结果表明，降频现象的发生是由于复位积分器的输出电压在n个时钟周期内不能达到参考电压V_ref，使得它无法在n个时钟周期内复位，只有在n+1个时钟周期内复位. 值得注意的是，在任一工作频率下，变换器无论工作在CCM还是DCM，均处于稳定状态；在主电路参数及时钟周期不变的情况下，DC关键词：降频现象单周控制Buck变换器稳定性

Reducing frequency phenomenon in Buck converters with one cycle control

This paper deals with the reducing frequency phenomenon in Buck converters with one cycle control. The critical conditions of its occurrance and operation modes are derived. The results show that the reducing frequency phenomenon occurs because the output voltage of the integrator does not rise to the reference voltage V_ref within n clock periods so that the integrator can not be reset in n clock periods but must be reset in the (n+1)th clock period. Furthermore, the converters are stable both in CCM and DCM when the reducing frequency phenomenon occurs. Meanwhile, the ratio of the intervals with the reference voltage V_ref between CCM and DCM is held constant. In addition, the ripple of the output voltage is increasing with the decrease of the circuit operating frequency. Finally, these theoretical results are verified by the numerical simulation and circuit experiment.