Three-phase bridge type 6-pulse full-controlled rectifier circuit principle

GW MB10F 0.8A 1000V rectifier bridge

Probe current voltage pin 420*4450 head diameter 5.0 over current current and voltage pin

WPM2006-6/TR

ESD5305F-6/TR

description:

The three-phase 6-pulse rectifier circuit is based on the three-phase full-wave rectifier circuit, and the diode is replaced by a thyristor. This small change has caused a huge change in the working mode of the rectifier:

1. The forward voltage between the anode and cathode of the diode rectifier VD is turned on as long as it is greater than the barrier voltage of its PN junction. However, when the thyristor rectifier VS has no trigger signal added to its gate, it does not conduct as long as the forward voltage between its anode and cathode does not reach the breakdown of the tube.

2. The conduction conditions of the thyristor rectifier VS are as follows:

a. The forward voltage between the anode and the cathode. For a diode rectifier, this voltage is turned on as long as it is around 0.7V; the thyristor is generally specified above 6V.

b. Control electrode trigger signal voltage. Thyristors are generally triggered by pulses. This voltage pulse is required to have a certain amplitude and width. Without a certain amplitude, the barrier voltage of the PN junction cannot be cancelled. Without a certain width, there is not enough time for the conduction to spread from one point to the other. The entire PN junction. Generally, the required amplitude is 3~5V, the width is 4~10 microseconds, and the trigger current is 5~300mA.

c. Maintaining current refers to the minimum current that is willing to maintain the thyristor rectifier VS conducting. Generally, for a thyristor of 20A to 200A, the holding current is specified to be less than 60mA.

d. Holding current refers to the minimum current that can continue to conduct after the thyristor is turned on and the control electrode trigger signal voltage disappears. This current is generally several times the holding current.

3. The control angle α and the conduction angle θ lead to these two parameters in order to characterize the control behavior of the thyristor to the AC voltage. The relationship between the control angle α and the conduction angle θ is given.

a. Control angle α, when the AC positive half wave is taught on the thyristor, has the basic conditions for turning on the thyristor. From the time when the AC sine wave crosses 0, until the thyristor is turned on (time b), the thyristor does not conduct for 0b, which becomes the control angle. Since the thyristor is turned on very quickly, generally less than 1 microsecond, it is considered that the time of adding the trigger signal is the time when the thyristor is turned on, that is, the general opening time is negligible.

b. Conduction angle θ. Since the opening of the thyristor is a positive feedback process, it cannot be automatically turned off after being turned on. This conduction process continues until voltage pot 0, and the period from on to off is called the conduction angle.

The input rectifier in the UPS circuit is controlled by the control of the above two parameters. This control is generally referred to as "phase control." Obviously, here α + β = 180 °, which means that as long as one of these two parameters is known, the other will know.