Ordinary thyristor is a semi controllable high-power semiconductor device that appeared in the 1970s. It is a pnpnpn four layer semiconductor structure, and an ordinary thyristor has three poles: anode, cathode, and gate; Thyristors have the characteristics of silicon rectifier devices and can operate under high voltage and high current conditions. Their emergence has expanded semiconductor devices from the weak current field to the strong current field. During the working process of an ordinary thyristor t, its anode a and cathode k are connected to the power supply and load, forming the main circuit of the ordinary thyristor. The gate g and cathode k of the ordinary thyristor are connected to the device controlling the ordinary thyristor, forming the control circuit of the ordinary thyristor. Working conditions of ordinary thyristors: 1 When an ordinary thyristor is subjected to reverse anode voltage, regardless of the voltage applied to the gate, the ordinary thyristor is in the off state. 2. When an ordinary thyristor is subjected to a forward anode voltage, it only conducts when the gate electrode is subjected to a forward voltage. 3. When an ordinary thyristor is on, as long as there is a certain positive anode voltage, regardless of the gate voltage, the ordinary thyristor remains on, that is, after the ordinary thyristor is on, the gate loses its function. 4. When the main circuit voltage (or current) of the ordinary thyristor is reduced to nearly zero under conduction, the ordinary thyristor will turn off