Reconfigurable Control of the Quasi-Parallel Voltage Regulator for Powering Laptop Processors

The quasi-parallel voltage regulator (VR) topology with a phase-shifted full-bridge (PSFB) converter and a synchronous buck converter (SBC) in quasi-parallel configuration gives high efficiency even with widely varying input voltage at high and medium loads but not at light loads. Moreover, the “loop gain shaping” approach to controller design for this converter does not give satisfactory dynamic performance. Therefore, this article proposes a state feedback controller which meets the stringent dynamic performance requirement of the VRs. Additionally, techniques to reconfigure the state feedback controller are proposed to operate this converter in different light-load operating modes to improve its light-load efficiency so that the converter becomes suitable for laptop VR application. In the light-load modes, the PSFB and the SBC operate alternately to regulate the load voltage, thereby saving the losses of one of the converters. At very light loads, a burst mode operation is proposed where both the converters remain inactive for most of the time, further increasing the efficiency. A unified control method which enables the converter to seamlessly change the operating modes of the converter, based on the computing load on the processor, is proposed and experimentally verified on a laboratory prototype for satisfactory performance.