Rectifier circuit output current waveform

The waveform of the output current of the silicon-controlled rectifier bridge of the three-phase thyristor rectifier circuit of the rectifier bridge is the main method to study the fault of the thyristor rectifier bridge. Therefore, the output current of the thyristor rectifier bridge is explained before discussing the fault detection and diagnosis of the thyristor rectifier bridge. Waveform. In the normal case of the thyristor rectifier bridge, when the thyristor rectifier bridge has a resistive load and an inductive load, the waveform of the output voltage and the waveforms of the AC side input current and the DC side output current are respectively as shown in the figure.

It can be seen from the figure that the waveforms of the positive and negative output currents of the DC side of the thyristor rectifier bridge are respectively the sum of the three-phase currents of the AC side + A + B + C and - A - B - C of the corresponding thyristor rectifier bridge. For inductive loads, since the current in the inductor cannot be abruptly changed, regardless of how the output voltage of the thyristor bridge changes, as long as the average value is constant, the current is substantially constant, especially due to the energy storage of the inductor, when the output voltage is negative. The output current of the thyristor rectifier bridge remains unchanged. At this time, the thyristor rectifier bridge is in an inverter state, that is, the energy stored in the inductive load is fed back to the AC side; and for the resistive load, the resistor only consumes energy. The energy cannot be stored, so the output voltage of the thyristor cannot be negative. The output current of the thyristor rectifier bridge changes in proportion to the output voltage of the thyristor rectifier bridge. When the output voltage of the thyristor is 0, The output current of the thyristor rectifier bridge also becomes zero.