# What is a thyristor? What are the functions in the circuit?

Last Update Time: 2018-10-29 13:51:49

What is a thyristor? What are the functions in the circuit?

Thyristor, also known as SCR,is a kind of controllable rectifier.The thyristor is expressed by the letter VS,which has the function of unidirectional conduction,it can also be used as a controllable switch.The main characteristic of the thyristor is that it can control the large power with the small power,so it is often used in the motor drive control circuit and the overload protection in the power supply devices, etc.

what are the parameters of the unidirectional thyristor and the bidirectional thyristor?

gate trigger current IcT gate trigger current is the minimum gate current required by the regulated environment temperature and the positive voltage between the thyristor anode and the cathode to make the thyristor switch from the off state to the conduction state.

the average current of the pass state average current I tau state refers to the average of the current through the A, K (or T1, T2) poles at the specified ambient temperature and the standard heat dissipation.

the forward turning voltage of the forward turning voltage (UBo) refers to the peak voltage corresponding to the transition from the shutdown state to the conduction state at the rated ambient temperature 100C and the opening of the gate G, with the positive voltage of the sinusoidal half wave between the anode A and the cathode K.

the reverse breakdown voltage UBR reverse breakdown voltage refers to the sinusoidal half wave reverse voltage between the thyristor anode and the cathode at the rated junction temperature, and the peak voltage corresponding to the increase of the current brushes in the common reverse lake.

reverse repetitive peak voltage URRM reverse repetitive peak voltage refers to the maximum reverse peak voltage allowed by the thyristor when the gate G is open. This voltage is reduced to the reverse breakdown voltage

The peak voltage after 100V.

the repeated peak voltage of the broken state repetition peak voltage UDRM is that the maximum peak voltage of the thyristor is allowed to be added to the A, K (or T1, T2) poles when the thyristor is in the forward turn. This voltage is about a forward turning voltage Uw

The voltage value after 100V is subtracted.

gate trigger voltage UcT gate trigger voltage refers to the minimum gate DC voltage required to change the thyristor from the off state to the conduction state under the conditions of the prescribed ambient temperature and the positive voltage between the thyristor anode and the cathode. The gate voltage is about 1.5V.

reverse repetitive peak current I RRM reverse repetitive peak current refers to the reverse maximum leakage current value of thyristor in shutdown state, generally less than 100 A.

gate reverse voltage gate reverse voltage refers to the rated voltage added on the gate of thyristor, usually not exceeding 10V.

the forward average voltage drop Up forward average voltage drop is also called the pass state average voltage or the pass state voltage drop voltage. It refers to the average value of the voltage drop between the anode A and the cathode K when the current of the thyristor is rated at the prescribed ambient temperature and standard heat dissipation, usually 0.4~1.2V.

Maintaining current IH is the minimum current that keeps the thyristor on. When the forward current is less than IH, the on-going thyristor will be turned off automatically.

Repeated repetitive peak current ( IDR ) off state repetitive peak current is the positive maximum average leakage current value of the thyristor in the disconnected state, generally less than 100A.

The peak value of the on-state peak voltage of the UTM peak voltage is the peak value of the tube voltage drop which is specified as the rated current. Generally 1.5 ~ 2.5 V,and increased slightly with the increase of anode current.

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