What Is a Thyristor?
The ordinary thyristor is a semi-controllable high-power semiconductor device, which appeared in the 1970s. It is a pnpn four-layer semiconductor structure. An ordinary thyristor has three poles: an anode, a cathode, and a gate; the thyristor has the characteristics of a silicon rectifier device and can work under high voltage and high current conditions. Its appearance has expanded the semiconductor device from the weak current field. To the field of strong electricity.
Ordinary thyristor
Right!
- The ordinary thyristor is a semi-controllable high-power semiconductor device, which appeared in the 1970s. It is a pnpn four-layer semiconductor structure. An ordinary thyristor has three poles: an anode, a cathode, and a gate; the thyristor has the characteristics of a silicon rectifier device and can work under high voltage and high current conditions. Its appearance has expanded the semiconductor device from the weak current field. To the field of strong electricity.
- During the operation of the ordinary thyristor t, its anode a and cathode k are connected to the power supply and the load to form the main circuit of the ordinary thyristor, and the gate g and cathode k of the ordinary thyristor are connected to the device controlling the ordinary thyristor to form the control of the ordinary thyristor. Circuit. Working conditions of ordinary thyristors: 1. When ordinary thyristors withstand reverse anode voltage, no matter what voltage the gates withstand, ordinary thyristors are turned off. 2. When a normal thyristor withstands a forward anode voltage, the ordinary thyristor will conduct only when the gate is with a forward voltage. 3. When the 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 turned on, the gate is disabled. 4. When the ordinary thyristor is on, when the voltage (or current) of the main circuit decreases to near zero, the ordinary thyristor is turned off.
- 1. udrm: thyristor withstand voltage in off-state repeated peak voltage. The ordinary thyristor udrm is 100v --- 3000v 2. urrm: When the reverse repetitive peak voltage control pole is disconnected, the reverse repetitive voltage acting on the thyristor can be repeated. Ordinary thyristors generally take urrm from 100v to 3000v) 3. itav: the average temperature of the on-state current is 40. At c, in a circuit with a resistive load, a single-phase power frequency sine half wave, and a conduction angle of not less than 170o, the maximum on-state average current allowed by the thyristor. The ordinary thyristor itav is 1a --- 1000a. ) 4. utav: On-state average voltage tube voltage drop. Under the specified conditions, when the sine half-wave average current is passed, the average voltage between the thyristor's anode and cathode. Generally about 1v. 5. ih: minimum sustaining current At room temperature, the minimum current required to maintain the conducting state after the control electrode is open and the thyristor is triggered to conduct. Usually several tens to more than one hundred milliamps. 6. ug, ig: Control electrode trigger voltage and current At room temperature, when the anode voltage is 6v DC, the minimum control electrode DC voltage and current necessary to make the thyristor fully conductive. Generally ug is 1 ~ 5v, and ig is tens to hundreds of milliamps.
- The main disadvantages of ordinary thyristors: poor overcurrent and overvoltage capabilities. The thermal capacity of ordinary thyristors is very small: once overcurrent, the temperature rises sharply, and the device is burned out. The ability of ordinary thyristors to withstand overvoltage is extremely poor: when the voltage exceeds its reverse breakdown voltage, it is easily damaged even if the time is extremely short. When the forward voltage exceeds the turning voltage, erroneous conduction will occur, and the current after conduction will be large, which will damage the device. First, over-current protection measures fast fuse: add a fast fuse in the circuit. Over-current relay: DC over-current relay over-current cut-off circuit is connected in series at the output end: the current feedback is used to reduce the conduction angle of the ordinary thyristor or stop the trigger, thereby cutting off the over-current circuit. Second, over-voltage protection resistance-capacitance absorption: use capacitors to absorb over-voltage. That is, the energy of the overvoltage is converted into electric field energy and stored in the capacitor, which is then consumed by the resistor. Selenium rectifier reactor: The selenium reactor is a non-linear element. It quickly breaks down after overvoltage, and its resistance is reduced to suppress overvoltage shock. After the high voltage, the selenium stack can return to the state before breakdown.