Circuit for simultaneous cut-off of two series connected high voltage power switches
AssigneeU.S. Philips Corporation
InventorDirk J. A. Teuling
Life of this patent
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Abstract
A circuit arrangement comprising at least two high-voltage power switches (e.g. transistors) connected in series to a high voltage source. In order to ensure that the switches are automatically cut off substantially simultaneously, the control means of each switch comprise a delay element for delaying the cut-off signal. A comparison stage controls the delay caused by at least one delay element as a function of the difference between the voltage present at the junction point of the switches and a reference voltage.
Claims20
A circuit arrangement comprising at least two high-voltage power switches connected in series and having control means for repeatedly cutting off the switches, said control means being connected to a signal source for producing a control signal for the switches, characterized in that, in order to ensure that the high-voltage power switches are automatically cut off substantially simultaneously, the control means for each switch comprise a delay element for delaying a cut-off signal of the said switch, the circuit arrangement further comprising a comparison stage for comparing a voltage present in operation at a junction point between the switches with a reference voltage and for controlling the delay caused by at least one delay element.
A switching circuit comprising:
- a pair of terminals for connection to a source of high voltage, first and second high voltage semiconductor switches connected in series between said pair of terminals, control means for supplying a periodic switching control signal to respective control electrodes of the first and second semiconductor switches to drive the first and second switches from a saturation state to a cut-off state, said control means including first and second delay elements coupled to the control electrodes of the first and second semiconductor switches, respectively, for delaying a cut-off control signal supplied to the respective control electrodes, a comparison device having a first input coupled to a junction point between the first and second semiconductor switches and a second input coupled to a source of reference voltage, means coupling an output of the comparison device to at least one of said first and second delay elements for controlling the delay time of said one delay element as a function of the voltages appearing at said first and second inputs of the comparison device and in a manner so as to substantially simultaneously drive the first and second semiconductor switches from said saturation state to said cut-off state.
Dependencies are inferred from the claim text.