JPH06339276A - Phase control method for thyristor rectifier - Google Patents

Abstract

(57) [Summary] [Purpose] To reduce the time required to charge the output-side smoothing capacitor at the initial startup of the thyristor rectifier. [Structure] A single-phase AC voltage supplied via an AC reactor 2 is rectified to charge a capacitor C _f and a current detection value of a current detector 5 of an input current of a rectifier 3 feeding a load 4 is input. An arc control circuit is provided, and the current detection value and the current upper limit value for control determined corresponding to the allowable current value of the rectifier are compared, and if the current detection value is less than or equal to the current upper limit value, the rectifier 3 Continuing the rapid increase in the conduction period for both thyristors, and if the relationship between the two comparison current values is reversed, the conduction period increasing control for both thyristors is stopped and the firing angle for both is increased. It is assumed that the value is maintained at the value at the time of suspension, and then the conduction period increasing control is restarted when the detected current value becomes smaller than the control upper limit value.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a phase control method in the initial stage of activation of a thyristor rectifier for quick charging of its output side smoothing capacitor.

[0002]

2. Description of the Related Art As a conventional phase control method for this kind of thyristor rectifier, there is known a rectifier circuit as shown in the circuit diagram of FIG. 2 and a control as shown in the operation waveform diagram of FIG. ing. In FIG. 2, 1 is a single-phase AC power supply, 2 is an AC reactor, and 3 is a single-phase structure in which both upper arms thereof are bridged by thyristors THY ₁ and THY ₂ and both lower arms thereof are bridged by diodes D ₁ and D _2. A rectifier for full-wave rectification, C _f is a capacitor for smoothing rectified voltage, and 4 is a load.

FIG. 3 shows a phase control pattern for each of the thyristors performed in the initial stage of startup until the charging of the capacitor C _f is completed. FIG. 3A shows an AC input supplied from the single-phase AC power supply 1. Voltage waveform diagram, Figure 3
FIG. 3B is a waveform diagram of the firing gate signal for the thyristor THY ₁ , and FIG. 3C is a waveform diagram of the firing gate signal for the thyristor THY ₂ .
It shows a change pattern with respect to.

As shown in the figure, with the passage of time, the conduction periods of both thyristors are sequentially controlled to increase at a predetermined rate for each cycle of the AC input voltage as T ₁ → T ₂ → T ₃ . That is, the conventional phase control method of the thyristor rectifier at the initial stage of startup is a time-dependent increase control at a predetermined ratio of the thyristor conduction period to control the charging current to the smoothing capacitor to an allowable current value considering both the thyristor and the diode. It is intended to avoid the generation of the charging inrush current by increasing the power in sequence while limiting to the following.

The conduction period of the thyristor is equivalent to the conduction angle in the case of displaying the phase angle.

[0006]

However, in the conventional phase control method of the thyristor rectifier as described above,
In order to limit the charging current to the smoothing capacitor in the initial stage of rectifier start up to the allowable current value or less throughout the entire charging period, the conduction angle initial value in the temporal expansion control at a predetermined ratio of the thyristor conduction angle as described above and The time expansion ratio has to be a value that is considerably suppressed,
Therefore, the time required for completion of charging in the smoothing capacitor also had to be long.

In view of the above, an object of the present invention is to provide a phase control method for a thyristor rectifier capable of shortening the time required to charge the output side smoothing capacitor while keeping the charging current below a predetermined allowable current value. It is what

[0008]

In order to achieve the above object, a phase control method for a thyristor rectifier according to the present invention is a thyristor rectifier for performing full-wave rectification on an AC input supplied via an AC reactor, which has a bridge structure. In the phase control method, the conduction angle of the thyristor forming the rectifier is set to a predetermined time for each cycle of the AC input in the initial startup until the charging of the rectifying voltage smoothing capacitor provided on the output side of the rectifier is completed. While gradually expanding with a gradient,
The input current of the rectifier is monitored, and when the value reaches a current upper limit value determined corresponding to the allowable current of the rectifier component, the conduction angle expansion control is stopped, and the thyristor conduction angle is expanded. It is assumed that the value at the time of suspension is held, and then the conduction angle expansion control is restarted when the input current value becomes smaller than the current upper limit value.

[0009]

In general, the terminal voltage of the capacitor, that is, its charging voltage is proportional to the integrated value of the charging current to this capacitor. On the other hand, in a rectifier having a rectified voltage smoothing capacitor on its output side, the sum of the load current as its output current and the charging current to the capacitor must always be smaller than the allowable current of the rectifier constituent elements. is there. Note that the problem of the rush current to the capacitor is usually in the initial stage of starting the rectifier, and at this stage, the output current of the rectifier is approximately the charging current to the capacitor.

Therefore, generally, in the charging of the capacitor, the integrated current value is continuously increased when the charging current is continuously and sequentially increased, and when the charging current is intermittently increased at the current upper limit value smaller than the allowable current. If they are the same, the final charging voltage of the capacitor is also the same, but in that the current integrated value per charge in the initial stage can be large, the rise of the capacitor charging voltage in the case of the intermittent charging is The speed can be higher than that in the case of the above-mentioned continuous progressive charge.

In accordance with the above, the present invention relates to a thyristor rectifier having a rectifying voltage smoothing capacitor on its output side, and the thyristor until the passing current of the rectifier component reaches a current upper limit value determined corresponding to the allowable current. Control the firing angle to rapidly increase the conduction period and accordingly the conduction angle, and when the passing current reaches the current upper limit value, the conduction period increase control is stopped to set the firing angle of the thyristor to When the input current becomes smaller than the current upper limit value, the conduction period increase control is restarted to maintain the current integral value per charge in the initial charging stage of the capacitor as much as possible. It aims to shorten the charging time.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will be described below with reference to the circuit diagram of FIG. In FIG. 1, constituent elements having the same functions as those in the embodiment of the prior art shown in FIG. 2 are designated by the same reference numerals. In FIG. 1, a current detector 5 provided on the input side of the rectifier 3 in the circuit diagram of FIG. 2 and an ignition control circuit 6 using the detected current value as an input signal are added, and the output of this ignition control circuit is added. The signal controls the firing angle of both thyristors THY ₁ and THY ₂ in the rectifier 3.

That is, the input current of the rectifier 3 detected by the current detector 5 is compared with the current upper limit value determined corresponding to both allowable current values of the thyristor and the diode which form the rectifier 3, If the value of the input current is less than or equal to the current upper limit value, the thyristors THY ₁ and THY _{2 are}
Continuing the rapid expansion of the conduction angle with respect to, and if the relationship between the two current values is reversed, the conduction angle expansion control of both thyristors is stopped and the conduction angle of both of them is the value at the time when the expansion control is stopped. Then, if the input current becomes smaller than the current upper limit value, the conduction angle expansion control is restarted.

Therefore, the charging current in the initial stage of charging of the smoothing capacitor is intermittent with its value being the upper limit value of the current, and the current integral value per time is higher than that in the case of the conventional method. As a result, the time required for charging the capacitor is shortened, and at the same time, the state in which the current flowing through the rectifier exceeds the allowable current value during the charging is also avoided.

[0015]

According to the present invention, the present invention relates to a thyristor rectifier for full-wave rectifying an AC input supplied via an AC reactor, and a phase control method applied to an initial stage of startup until completion of charging of an output-side smoothing capacitor. , While increasing the conduction angle of the thyristor with a predetermined time gradient,
When the input current of the rectifier is monitored and the input current reaches a current upper limit value that is determined corresponding to the allowable current of the rectifier constituent element such as a thyristor, the conduction angle expansion control is stopped and the conduction angle of the thyristor is set to this value. The value is maintained at the value at the time of stopping the control, and thereafter, when the input current becomes smaller than the current upper limit value, the conduction angle expansion control is controlled to restart, thereby intermittently The amount of charge becomes large, the rising speed of the charging voltage of the capacitor becomes large, and the time required for charging is shortened, and at the same time, avoiding the state where the energizing current of the rectifier exceeds its allowable current value during the charging. You can

[Brief description of drawings]

FIG. 1 is a circuit diagram of a thyristor rectifier showing an embodiment of the present invention.

FIG. 2 is a circuit diagram of a thyristor rectifier showing a prior art embodiment.

FIG. 3 is an operation waveform diagram of a control operation corresponding to FIG.

[Explanation of symbols]

1 Single-phase AC power supply 2 AC reactor 3 Rectifier (for single-phase full-wave rectification) 4 Load 5 Current detector 6 Firing control circuit C _f Smoothing capacitor D Diode (D ₁ , D ₂ ) THY Thyristor (THY ₁ , THY) ₂ )

Claims (1)

[Claims] 1. A method for controlling a phase of a thyristor rectifier for full-wave rectifying an AC input supplied via an AC reactor in a bridge structure, wherein charging of a rectifying voltage smoothing capacitor provided on an output side of the rectifier is completed. In the initial stage of starting up, the conduction angle of the thyristor that constitutes the rectifier is gradually expanded with a predetermined time gradient for each cycle of the AC input, and the input current of the rectifier is monitored and the value is allowed by the rectifier constituent elements. When the current upper limit value determined corresponding to the current is reached, the conduction angle expansion control is stopped, and the conduction angle of the thyristor is held at the value at the time of this expansion control stop, after which the input current value is A phase control method for a thyristor rectifier, wherein the conduction angle enlargement control is restarted when the current value becomes smaller than the current upper limit value.