Patent ID: 7456615

Claim:
A charging arrangement for capacitor means, the arrangement being arranged to be supplied by a voltage containing network cycles, and comprising a gate-controlled semiconductor switch (T ch ) arranged for charging the capacitor means (C aux ), and means for generating a control signal of the gate-controlled semiconductor switch, wherein the means for generating the control signal include a clipper, a first integrator, a second integrator, a cycle indicator, a reset device, an adder, a restricting circuit, a trigger circuit, and an isolation transformer, wherein the clipper is arranged to restrict the supplying voltage containing network cycles to be substantially a square wave having a predetermined amplitude, the cycle indicator is arranged to indicate when a network cycle of the supplying voltage ends, the first integrator is arranged to form, from the square wave, a ramp wave whose value is reset by the reset device at the end of each network cycle in order to generate a sawtooth wave voltage signal, whereby information about the ending of each network cycle is obtained from the cycle indicator, the second integrator is arranged to generate, from the square wave, a ramp wave voltage signal whose value increases during each network cycle until the restricting circuit stops the increase in the value of the ramp wave voltage signal when predetermined conditions are fulfilled, the adder is arranged to add up the sawtooth wave voltage signal of the first integrator and the ramp wave voltage signal of the second integrator into a sum signal (U Σ ), and the trigger circuit is arranged to supply an ignition pulse to a gate of the semiconductor switch (T ch ) via the isolation transformer when the sum signal (U Σ ) exceeds a predetermined trigger level.