What is the control mode of the server AC voltage regulating circuit?
This article mainly introduces the relevant knowledge of "what is the control mode of server AC voltage regulating circuit". The editor shows you the operation process through an actual case, and the operation method is simple, fast and practical. I hope this article "what is the control mode of server AC voltage regulating circuit" can help you solve the problem.
(1) for on-off control
As shown in figure an above: the on-off control is to turn on or turn off the thyristor when the AC voltage crosses zero, so that the load circuit is connected with the AC power supply for several cycles, and then several cycles are disconnected, by changing the ratio of the turn-on cycle number to the turn-off cycle number, to achieve the purpose of adjusting the AC voltage.
During the on-off control, the output voltage waveform is basically sinusoidal and there are no low-order harmonics, but due to the occasional output voltage and discontinuous voltage regulation, fractional harmonics will be decomposed. If it is used for voltage regulation and speed regulation of induction motor, it will have a large current shock because the motor is often in the process of reclosing, so it is rarely used. It is generally used for AC power regulation such as temperature regulation of electric furnace.
(2) Phase-controlled
As shown in figure b above: similar to the phase shift trigger control of controllable rectifier, the positive thyristor is triggered in the positive half cycle of the AC, and the reverse thyristor is triggered in the negative half cycle, and the phase shift angle of the two thyristors is kept the same. to ensure the output of positive and negative half-cycle symmetrical AC voltage waveforms to the load.
The phase control method is simple and can continuously adjust the output voltage. However, the output voltage waveform is non-sinusoidal and contains rich low-order harmonics, which will cause additional harmonic loss and pulsating torque in the application of voltage regulation and speed regulation of induction motor.
(3) Chopper control
As shown in figure c above: chopping control uses pulse width modulation technology to divide the AC voltage waveform into pulse trains, and the output voltage can be adjusted by changing the duty cycle of the pulse.
The output voltage of chopper control can be adjusted continuously and the harmonic content is small, which basically overcomes the shortcomings of phase and on-off control. Because the voltage regulating circuit with chopper control needs to turn on and off at higher frequency within half a week, thyristors can not be used, and high frequency self-turn-off devices such as GTR, GTO, MOSFET, IGBT and so on must be used.
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