News
Thyristor DC regulator
The DC regulator using thyristor SCR as adjustment element is called thyristor DC regulator. Since thyristor works in the switching state, it is also a switching regulator. Its block diagram is the same as the block diagram of transistor DC switching regulator. R1 and R2 are sampling resistors, and the voltage regulator BG. The voltage on is the reference voltage, and BG and BG2 form a comparison amplifier. R3, C2, single junction transistor UJT and transformer B2 form a pulse oscillator. The generated pulse is used to trigger thyristor SCR1 and SCR2, and the phase shift of the oscillation pulse is controlled by the comparison amplifier. The two thyristors are used for both rectification and adjustment switches. BG, L, C: form a filter to smooth the pulsating component of the rectified voltage.
Let the range of non-conduction of thyristor under forward voltage be called control angle (some are called cut-off angle or trigger delay angle), represented by a, and the conductive range be called conduction angle, represented by 0. When the output voltage of the voltage regulator is the specified value, the conduction angle of the thyristor is a certain value. When the output voltage changes due to changes in the grid voltage or load current, this change is taken by the sampling resistor and compared with the reference voltage. The difference is amplified by the amplifier to control the phase shift of the trigger pulse output by the oscillator, so that the conduction angle of the thyristor changes to increase or decrease the DC output voltage.
Compared with the transistor switching regulator, its switching frequency is low (the fundamental frequency of the voltage after rectification), so the volume of LC is larger. In addition, the adjustment time, voltage regulation coefficient, ripple voltage, etc. are not as good as the former. However, the thyristor regulator can obtain an output of kilowatts or even more power, and the efficiency is also higher.
∷
vigce
vigce
vigce