Patent ID: 7961484
Filing Date: 2011-06-14
Classification: H02M,H03F,H03K,Y02B

Abstract:
1. A power converter comprising a bipolar switching device switching an inductive load, said power converter including a closed-loop control system for controlling the degree of saturation of said bipolar switching device when said bipolar switching device is switched on, said bipolar switching device having a collector terminal connected to switch said inductive load and a control terminal for controlling said switching, said closed-loop control system comprising: a voltage sensing system to sense a voltage on said collector terminal and to provide a voltage sense signal; a controller having an input coupled to receive said voltage sense signal from said voltage sensing system and having a control signal output; and a drive modulation system coupled to said output of said controller for modulating a drive to said control terminal of said bipolar switching device responsive to said controller control signal; and wherein said controller is configured to monitor changes in said sensed voltage during a period when a drive signal is applied to said control terminal of said switching device, said drive signal to drive said switching device to be on and said controller configured to control said drive modulation system to control said degree of saturation of said bipolar switching device when said drive signal maintains said switching device on, wherein said voltage sensing system comprises a first capacitor, one side of said first capacitor being coupled to said collector terminal of said switching device and a second side of said first capacitor being coupled to a reset device to reset a voltage on said first capacitor when a said drive signal to drive said switching device on is applied to said control terminal, whereby said changes in said sensed voltage when said drive signal maintains said switching device on subsequent to said reset may be monitored by said controller to control said drive modulation system to control said degree of saturation of said bipolar switching device.