JPS5852436B2 - semiconductor rectifier - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a controlled rectifier with a limited DC output control range, and more particularly to a low cost controlled rectifier.

Conventionally, silicon rectifiers have been widely used in, for example, DC substations for electric railways, and the DC output voltage of the silicon rectifier changes depending on the load current according to the DC voltage fluctuation rate of the equipment.

For this reason, if a design is made so that the rated DC voltage can be obtained when the rated DC current is applied, there is a risk that the DC voltage will rise when the load is light or there is no load, which will have an adverse effect on the DC circuit equipment.

Further, when the power supply voltage increases, the DC voltage similarly increases, and there is a danger that it will have an adverse effect on the load equipment.

However, the DC voltage increase due to DC voltage fluctuation rate, power supply fluctuation, etc. is generally small, about 5 to 15 μm, but if a Sirisk rectifier is used instead of a silicon rectifier to compensate for this, the equipment cost will increase significantly. There was a growing problem.

The present invention is intended to solve this problem, and provides a low-cost rectifier in which a diode and a silice are connected in series to form a rectifier arm and are controlled only during a predetermined DC voltage. be.

FIG. 1 shows an embodiment of a rectifier according to the invention.

1 is a three-phase full-wave connected rectifier, and the rectifier arm 2u is composed of a thyristor 3 and a diode 4 in series.

5 is a detection device for detecting the DC voltage of the rectifier 1, 6
is a DC setting voltage signal generator, and 7 is a DC voltage detection device 5.
a comparison device for generating a phase control signal to the thyristor 3 by comparing the signal from the reference voltage signal generation device 6 and the reference voltage signal generation device 6;
8 is an α limiter device for preventing the phase control angle α to the thyristor 3 from becoming larger than a preset maximum value αmax, and 9 is a thyristor gate pulse generator.

Fig. 2 shows the operating waveforms of the rectifier in Fig. 1. Fig. 2 a shows the rectifier AC side phase voltages eu, ev, ew, and Fig. 2 shows the waveforms of the rectifier arm 2u at the maximum value αmax of the phase control angle of the rectifier. Shows voltage waveform.

However, Es represents the effective value of the rectifier AC side line voltage.

Also, the commutation type angle is ignored. Next, the operation of the present invention will be explained.

As the load current of the rectifier 1 decreases, the DC voltage gradually rises, and when the detection signal from the voltage detection device 5 reaches a signal determined by the gate reference voltage signal generator 6, the comparator 7 operates to close the gate. The thyristor 3 is controlled via the pulse generator 9 to suppress the DC voltage.

However, when the comparison device 7 generates a signal that causes the thyristor control angle α to exceed αmax due to power fluctuations, haze load fluctuations, etc., the α limiter device 8 sets the control angle α
is held at αmax, and α does not increase any further.

As is clear from Figure 2, the maximum reverse voltage applied to the rectifier arm 2u is
It is maximum when the phase angle is 90° regardless of JE E s
becomes.

-The force forward blocking voltage is the phase control angle α between α=0° and 90°.
It becomes maximum at the point 4E s sin α.

Therefore, if the α limiter device 8 is provided as in the present invention, the maximum forward blocking voltage of the rectifier arm 2u can be (sin αmax) x 100% of the maximum forward blocking voltage, as shown in FIG. The rectifier arm 2u does not need to be entirely sirisk, and the voltage V'TE s s i
Only for na (talking thyristor 3 and remaining V1 Kei 5 (1-
It is made up of a series body of diodes 4 that can withstand sin α), and the number of si-risks can be reduced.

For example, when αmax in FIG. 2 is set to 30°, the rectifier arm 2u has a ratio of (sin αmax)X100=50, so half of it can be replaced with diodes, which is economical.

In this way, when the voltage control range of the rectifier is limited and the maximum phase control angle αmax is 900 or less, by providing an α limiter device that operates at αmax, it is possible to replace part of the si risk with a diode, which is economical. A rectifier is obtained.

FIG. 3 shows another embodiment of the present invention, in which the forward voltage of the thyristor 3 is detected instead of the α limiter device 8 of FIG.
This voltage is set to a preset value (for example, 4Essi).
A forced firing circuit (anode firing circuit) uses the main circuit voltage generated between the anode and cathode of Thyristor 3 to send a gate signal and forcibly fire it when nαmax or the withstand voltage of Thyrisk 3 is reached. )10
It has been established.

It is clear that the same effects as in the embodiment shown in FIG. 1 can be obtained in this embodiment as well.

FIG. 4 shows an example of the operating characteristics of the rectifier of the present invention.

Characteristic curve a (dotted line) shows the characteristics of a conventional silicon rectifier, where at DC rated current Idn, DC rated voltage Edn
If the design is made so that the DC voltage is Edo when there is no load.
rises to.

On the other hand, curve b (solid line) shows the characteristics of the rectifier according to the present invention, where the haze current is reduced by Id1 and the DC voltage is reduced by
When the voltage rises to dl, the signal from the DC voltage detection device 5 in FIG. do.

By doing so, it is possible to suppress the increase in DC voltage during light loads without causing a significant increase in the cost of the rectifier.

[Brief explanation of drawings]

Fig. 1 shows an embodiment of the present invention, Fig. 2 shows the operating waveform of the rectifier shown in Fig. 1, Fig. 2 a shows the voltage on the AC side of the rectifier, and Fig. 2 shows the voltage waveform of the rectifier arm 2u. There is. FIG. 3 is a diagram showing another embodiment of the present invention, and FIG. 4 is a diagram showing the DC side characteristics of the rectifier of the present invention. In the figure, the same reference numerals indicate the same or equivalent parts, 1 is a rectifier, 2u is a rectifier arm, 3 is a cyrisk, 4 is a diode, 5 is a DC voltage detection device, 6 is a reference voltage signal generator, 7 is a comparison device, 8 is a phase control angle limiter device, 9 is a gate pulse generator, and 10 is a forced firing circuit for the thyristor 3.

Claims (1)

[Claims] 1 In a semiconductor rectifier that rectifies alternating current and obtains direct current output, a rectifier that obtains direct current output from alternating current by making a predetermined connection with a rectifying arm consisting of a series body of a silice and a diode, and a direct current voltage from the rectifier. a detecting device for detecting the thyristor; a comparing device for generating a phase control signal to the thyristor by comparing the detected DC voltage signal from the detecting device with the DC setting voltage signal from the DC setting voltage signal generator; an α limiter device that takes in a phase control signal from the device and prevents the phase control angle α of this phase control signal from exceeding a preset value of 90 degrees or less; A semiconductor rectifier comprising: a thyrisk gate pulse generator that generates a thyrisk gate pulse for controlling the thyrisk.