Patent ID: 6507177
Filing Date: 2003-01-14
Classification: H02M,Y02B

Abstract:
A control circuit for the power-controlled operation of a load in a portion of a load range, said load range extending between no load and full load, comprising:a semiconductor switch which is effective in a load circuit to enable pulse width modulation of a voltage supplied to said load for controlling power supplied to said load, and a drive circuit for the semiconductor switch, said drive circuit being adapted to generate a control signal for controlling said semiconductor switch, for controlling said load in said portion of said load range, said control signal comprises drive pulses following one after the other and separated by interpulse periods, and in an upper portion of said portion of said load range, the control signal comprises: a first pulse signal, with first individual pulses following one another with a first pulse frequency, and a second pulse signal, with second individual pulses following one another with a second pulse frequency in the interpulse periods of the first pulse signal, the second pulse frequency being greater than the first pulse frequency by at least a factor of ten, wherein in the upper portion of said portion of said load range at least one of the first and the second pulse signals is pulse width modulated for controlling said load.