Patent ID: 7855524

Claim:
A voltage control circuit, comprising: a) a first and second solid state switching device each of which includes: i) an input terminal; ii) an output terminal; iii) a control terminal adapted to receive a chopping signal, wherein a value of the chopping signal determines whether electric current can flow between the input terminal and the output terminal; b) a first diode having an anode and a cathode and a second diode having an anode and a cathode, wherein the output terminal of the first switch and the input terminal of the second switch are adapted to receive an AC voltage, wherein the input terminal of the first solid state switching device is connected to the cathode of the first diode and the output terminal of the second solid state switching device is coupled to the anode of the second diode, wherein the anode of the first diode and the cathode of the second diode are electrically coupled to a node; c) a third and fourth solid state switching device, each having: i) an input terminal; ii) an output terminal; iii) a control terminal adapted to receive a polarity signal, but not the chopping signal, wherein the polarity signal has the same frequency as the AC voltage and is synchronous with the AC voltage, wherein a value of the polarity signal determines whether electric current can flow between the input terminal and the output terminal; and d) a third diode having an anode and a cathode and a fourth diode having an anode and a cathode, wherein the input terminal of the third solid state switching device is coupled to the cathode of the third diode and the output terminal of the fourth solid state switching device is coupled to the anode of the fourth diode, wherein the anode of the third diode and the cathode of the fourth diode are electrically coupled to the node, wherein the output terminal of the third switch and the input terminal of the fourth switch are adapted to couple to a neutral line of an AC source.