Use unidirectional thyristor instead of bidirectional thyristor

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Use unidirectional thyristor instead of bidirectional thyristor [Copy link]

The circuit form of using unidirectional thyristors instead of bidirectional thyristors is:
two unidirectional thyristors are connected in reverse parallel, and

the triggering requirements are:
the pulses of the two thyristors are 180 degrees apart, and it is best to design the dead angle time.
The triggering signal requirements of general thyristors are sufficient. The triggering power and anti-interference requirements are determined according to the empirical value and typical value.
There are also different requirements for the starting point.
If the power of the trigger circuit is not enough, it is easy to cause poor triggering, and the obtained waveform is unstable, which has a greater impact on the load.
If used in the speed regulation of a three-phase motor, it often reflects that the motor has large mechanical noise, violent vibration, instability, and chaotic feedback signals, which can easily cause self-excitation of the circuit.
Triggering waveform requirements: the leading edge should be steep, the middle should be flat, the trailing edge should be straight, there should be sufficient triggering power, and the isolation transformer should have a high withstand voltage value, otherwise it is easy to cause damage to the isolation transformer! Even damage to the previous circuit,