Control strategy for constant voltage/constant current switching-mode instrumentation power supply

A strategy for realizing a switching-mode instrumentation power supply (SMIPS) by zero-voltage switching pulse-width modulation (ZVS-PWM) technique is presented. The proposed ZVS-PWM SMIPS is capable of constant-voltage (CV) and constant-current (CC) control with adjustable output voltage/current. A control strategy realized by a voltage-adjusted controller (VAC) and a current-limited controller (CLC) is proposed. A linear voltage regulator (LVR) with low loss is used at the output end for voltage regulation. A system modeling for describing the SMIPS behavior in CC and CV modes is conducted. A 500 W ZVS-PWM SMIPS is designed and realized to assess the system performance and it can gain an efficiency of 90%, good voltage regulation of within /spl plusmn/0.2% in CC mode, and good current regulation of within /spl plusmn/2% in CV mode.