Improved Current-Mode Control with Single-Step Load Transient

Description:

Non-linear single-step load transient improvement structures are proposed for current mode controlled converters. Two popular variable-frequency current mode controls are Constant On-Time (COT) and Ramp Pulse Modulation (RPM) due to their fast transient response. However, conventional COT and RPM both need multiple steps to increase inductor current during load step-up transient. The fastest transient response should be a single-step response. In this invention, two methods are proposed to achieve single-step load transient for current mode controls by improving the current control structures. For both methods of improvement, the operation mechanisms of the control remains unchanged. The proposed improvements can be used for RPM and COT in single-phase and multi-phase. Simulation results are presented to confirm the proposed improvements.