Wide range single-phase/polyphase switching power supply

Abstract

A wide range single-phase/polyphase switching power supply is presented. The power supply comprises first and second full wave bridge circuits. The rectified outputs of the bridge circuits are connected to a preregulator circuit, i.e., a FET circuit, where the primary input voltage from bridge circuits is limited. The output of the preregulator circuit is presented to a filter circuit. A current mode controller circuit operates at a fixed frequency with a variable duty cycle. An output of the current mode controller circuit drives the gate of a switching FET, at the fixed frequency and variable duty cycle. The aforementioned filtered voltage signal and the drain of the switching FET are connected across a first winding on the primary side of a flyback transformer. A second winding on the primary side of the flyback transformer is connected across Vcc, the supply voltage of the current mode controller circuit. The winding on the secondary side of the flyback transformer is connected to a voltage and filter circuit. Feedback is provided by an opto-isolator from the output voltage back to the compensation input of the current mode controller circuit. A voltage reference V.sub.REF is used in the feedback by an error correction amplifier to provide the feedback signal. The power supply of the present invention is particularly well suited for use with electronic electricity meters as such allows a common voltage reference for the power supply and the meter to be used. In a preferred embodiment, the second full wave bridge circuit is carried on a separate circuit board. The attachment of the second bridge circuit board on the main power supply circuit board converts the power supply from a single phase power supply to a polyphase power supply.

Dependencies are inferred from the claim text.