JPH0350504B2 - - Google Patents

Description

[Detailed description of the invention] [Structure of the invention] (Industrial application field) The present invention relates to a controlled rectifier ignition control device.

(Prior Art) FIG. 1 is a main circuit diagram of a typical power converter using three-phase bridge-connected controlled rectifier elements.

The three-phase AC power supply 1 is composed of AC power supplies eu, ev, and ew that have a phase difference of 120°, and the controlled rectifier 2 is composed of six controlled rectifier elements U, V, W, X, Y, and Z. The reactor 3 smoothes the current flowing to the load 4.

FIG. 2 is a waveform diagram for explaining the operation of the controlled rectifier 2. In the figure, the solid line A is the voltage waveform of the DC positive side point P with respect to the neutral point O of the AC power source 1, and the dotted line is the voltage waveform of the DC negative side N point with respect to the O point. U, V, W, X, Y, Z marked on the waveform
The symbol indicates the correspondence with the controlled rectifier that is energized during that period. The solid line in (b) shows the voltage between P and N, that is, the output voltage waveform of the control rectifier 2, and the dotted line shows its DC component, that is, the average voltage.

When operating with a constant control angle, U, Z, V,
It is well known that each controlled rectifier element is fired in the order of X, W, and Y, and the output of the controlled rectifier 2 becomes as shown in FIG. 2B. (However, the overlap angle at the time of commutation is ignored.) In this case, the control rectifier elements U, V, connected to the positive DC side,
Any one of the controlled rectifying elements W and any one of the controlled rectifying elements ) is commutated and energized, and the voltage waveform shown in b is output.

In this way, the double pulse method and the carrier pulse method are generally used for the ignition signal of the control rectifying element bridge-connected on the positive side and the negative side. The controlled rectifier starts energizing by applying a pulse signal to its gate terminal, and continues to energize even if the signal at the gate terminal disappears. Therefore, basically, it is sufficient to give one pulse signal to the positive (or negative) side control rectifying element at the time of starting energization, but at that point, the negative (or positive) side control rectifier that forms the current path is The controlled rectifier of the other phase must be ignited. Normally, this negative (or positive) side controlled rectifier is already supplied with an ignition pulse and is energized, but in the case where the current continues or when starting, this controlled rectifier is also ignited at the same time. The method of applying pulses is the double pulse method. Therefore, one controlled rectifying element has two
ignition pulses are given.

Further, the carrier pulse method is a method in which a pulse train is continuously applied during the energization period. If the inductance of the smoothing reactor is large, one pulse signal may not increase the current to a value sufficient for the control rectifier to continue energizing (called the holding current), and ignition may fail. . Also, depending on the ignition timing, even if one ignition pulse is applied at the time of starting energization, sufficient forward voltage is not applied to the control rectifier, so the above phenomenon is exacerbated and ignition is not possible. Sometimes. In such a case, during the period when the gate terminal of the controlled rectifier is energized,
A carrier pulse method that adds a pulse train continuously is effective.

Figure 2 C shows a double-pulse control rectifier U.
2 shows the ignition signal waveform of the same element U using the carrier pulse method.

(Problem to be solved by the invention) However, although the conventional carrier pulse method does not fail in ignition and is highly reliable, it requires a large amount of power for the ignition pulse generation circuit, and the control rectifier The drawback is that the pulse transformer used to insulate and send the ignition pulse signal is large.

The present invention has been made in view of the above circumstances, and an object of the present invention is to obtain an ignition pulse generation circuit for a controlled rectifier that is highly reliable, consumes low power, and can use a small and lightweight pulse transformer.

[Structure of the invention]

(Means and Effects for Solving the Problem) In order to achieve the above object, the present invention provides a device for controlling the firing phase of a plurality of bridge-connected control rectifier elements constituting a three-phase full-wave rectifier circuit. , a detection means for detecting the beginning of the energization period command of each control rectifier and generating a trigger signal; a timer means for generating a predetermined logic signal for a fixed period of time according to the trigger signal; An ignition control device for a control rectifier, comprising a pulse generation means for generating a pulse signal, and a pulse amplification means for outputting an ignition pulse to each control rectifier element based on the energization period command, the logic signal, and the logic conditions of the pulse signal. It is.

(Embodiment) FIG. 3 shows an embodiment of the ignition control device for a controlled rectifier according to the present invention. 5 to 10 and 12 are monostable multivibrators, 11 and 14 are or gates,
13 is an astable multivibrator, 15 to 20 are AND gates, 21 to 26 are pulse amplifiers, 27
-32 is a pulse transformer.

An energization period command signal 33U, 33V, 33W, 33X, 33 for each control rectifier element U, V, W, X, Y, Z is sent as an input signal from a phase control section (not shown).
Y, 33Z are given as shown in FIG. The monostable multivibrators 5 to 10 generate pulse signals at the rising edge of each energization period command signal 33U to 33Z. These pulse signals are logically summed by an OR gate 11 and combined into one energization start pulse signal 11a. This energization start pulse signal 11a is further input to the monostable multivibrator 12, and the ignition pulse train output period signal 1
2a is created. The pulse width of this ignition pulse train output period signal 12a is set to about 1/12 of the power supply cycle (30° C.). The astable multivibrator 13 oscillates and outputs a predetermined pulse train 13a, and this pulse train 1
3a and normal start pulse signal 11a are OR gate 1
4, the ignition pulse train signal 14a is obtained.
is made. This ignition pulse train signal 14a is input to AND gates 15 to 20, and each AND gate 15 to 20 outputs an energization period command signal 33U to 33.
Z and the firing pulse train output period signal 12a are ANDed and amplified by pulse amplifiers 21-26 to a signal of sufficient magnitude to fire the controlled rectifier. And pulse transformers 27-32
As shown in FIG. 4, the gate signals 34U to 34Z are applied to the gate terminals of the control rectifying elements U to Z, respectively.

As shown in FIG. 4, the gate signals 34U to 34Z of each controlled rectifying element exist only in the first period and the third period of the energization period divided into four, and the first period is the time when energization of the controlled rectifying element starts. Then, in the third period, a pulse train is output for a fixed period (30°) from the time when the control rectifier starts energization next.

〔Effect of the invention〕

As explained above, according to the ignition control device for a controlled rectifier according to the present invention, the power required for the ignition pulse circuit is halved, while maintaining the ignition reliability similar to that of the conventional carrier pulse method, and the pulse transformer It can also be half the size, providing an economical and reliable controlled rectifier ignition control device.

[Brief explanation of drawings]

Fig. 1 is the configuration of a three-phase full-wave controlled rectifier, Fig. 2 is a waveform diagram showing the operation of the three-phase full-wave controlled rectifier and a conventional ignition pulse, and Fig. 3 is a ignition control device for a controlled rectifier according to the present invention. In one embodiment, FIG. 4 is a waveform diagram for explaining the operation of FIG. 3. 1...Three-phase power supply, 2...Control rectifier, 3...Smoothing reactor, 4...Load, 5-10, 12...
Monostable multivibrator, 11, 14...OR gate, 13...astable multivibrator, 1
5-20...AND gate, 21-26...Pulse amplifier, 27-32...Pulse transformer.

Claims (1)

[Claims] 1. In a device for controlling the firing phase of a plurality of bridge-connected controlled rectifying elements constituting a three-phase full-wave rectifying circuit, a trigger is generated by detecting the beginning of the energization period command for each controlled rectifying element. a detection means for generating a signal; a timer means for generating a predetermined logic signal for a certain period of time in response to the trigger signal; a pulse generation means for generating a pulse signal of a certain pulse width at a certain period; and the energization period command. An ignition control device for a controlled rectifier, comprising a pulse amplifying means for outputting an ignition pulse to each control rectifier element based on the logic conditions of the logic signal and the pulse signal.