JP3509782B2 - Rectifier circuit - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rectifying circuit, and more particularly to a rectifying circuit suitable for a rectifying / smoothing circuit for converting power from AC to DC. 2. Description of the Related Art FIG. 3 is a diagram showing a general rectifying / smoothing circuit 300 for performing power conversion (forward conversion) from AC to DC. The rectifier / smoothing circuit 300 includes a rectifier circuit 310,
And a smoothing circuit 320. Rectifier circuit 310
Is constituted by connecting diodes 302 and 303 connected in series and diodes 304 and 305 connected in series, and an AC power supply 301 connected between a signal input terminal of the diode 302 and a signal input terminal of the diode 304.
Full-wave rectification of the AC voltage (current) supplied from the The smoothing circuit 320 includes a capacitor 306 connected in parallel with the rectifier circuit 310, and integrates the signal rectified in the full-wave rectifier circuit 310 and converts the signal into a smooth DC signal. In the rectifying / smoothing circuit 300 having the above configuration, immediately after the AC power supply 301 is turned on, an extremely large charging current flows into the capacitor 306 of the smoothing circuit 320 in a short time. The flow of the extremely large charging current may damage the capacitor 306 or shorten its life. Further, when the extremely large charging current flows, the diodes 302 to 305 included in the rectifier circuit 310 may be damaged. FIG. 4 shows a rectifying / smoothing circuit 3 shown in FIG.
This is a circuit in which a resistor circuit 330 that is enabled only for a predetermined time after the AC power supply 301 is turned on is added to the subsequent stage of the rectifier circuit 310 of FIG. The resistor circuit 330 includes a current limiting resistor 307 and a relay switch 308 connected in parallel. When the AC power supply 301 is turned on, the relay switch 3
08 is off for a predetermined time. The predetermined time is a time (generally several seconds) until charging of the capacitor of the smoothing circuit 320 is completed. When the relay switch 308 is turned off, the charging current flowing into the capacitor 306 per unit time is reduced by the resistor 307.
This can prevent a large charging current from flowing into the capacitor 306. After a lapse of a predetermined time, the relay switch 308 is turned on. As a result, the resistance 30
7 is short-circuited. However, there is a problem that the size of the current limiting resistor 307 increases. Further, there is a problem that the relay switch 308 is large in size and requires a circuit for controlling the square root. Accordingly, the present invention provides a circuit for a subsequent stage, for example, a capacitor constituting a smoothing circuit when an AC power is turned on, without using large circuit elements such as a relay switch and a current limiting resistor. It is an object of the present invention to provide a rectifier circuit provided with a mechanism for protecting the rectifier, and a rectifier / smoothing circuit provided with the rectifier circuit. [0007] A rectifier circuit according to the present invention is a rectifier circuit comprising an on-function controllable switch for rectifying an AC signal supplied from an AC power supply, wherein the rectifier circuit is disposed at a subsequent stage of the rectifier circuit. In the case where a circuit having a circuit element that is damaged by the entire current after the rectification flows immediately after the AC power supply is turned on is provided, the on-function control switch is turned on at least for a predetermined period immediately after the AC power supply is turned on. A first circuit that outputs a sawtooth-shaped first signal that increases or decreases at a predetermined cycle, and a first signal that is output from the first circuit and a second signal within the cycle. A second circuit that outputs a second signal that decreases or increases in a direction in which the first signal increases or decreases so as to intersect with the first signal; The first signal and the second signal are turned on only for a time.
And a third circuit for generating a third signal for turning on or off the on-function control switch in response to the intersection of the signals. [0010] In the rectifier circuit of the present invention, all the current after rectification by the rectifier circuit flows into the subsequent stage of the rectifier circuit immediately after the AC power is turned on. In the case where a circuit having a circuit element that is damaged by the above, for example, a smoothing circuit is provided, the amount of output current is regulated so that the charging current gradually flows into the capacitor of the smoothing circuit after the AC power is turned on. A control circuit is provided. Less than,
The configuration and operation of the rectifier circuit according to the embodiment having the above features will be described. FIG. 1 shows a full-wave rectifier circuit 2 according to an embodiment.
FIG. 2 is a diagram illustrating a configuration of a rectifying / smoothing circuit 200 including a rectifying / smoothing circuit 10. 2A to 2G show the signal waveforms at points P1 to P5 in the control circuit 100 immediately after the power is turned on, the output waveform of the rectifier circuit 210 flowing at point P6, and the smoothing flowing at point P7. FIG. 3 is a diagram illustrating an output waveform of a circuit 220. The rectifying / smoothing circuit 200 includes a full-wave rectifying circuit 210 and a smoothing circuit 220. The rectifier circuit 210 is a full-wave rectifier circuit including a thyristor that is an on-function controllable switch, and includes thyristors 202 and 203 connected in series and thyristors 204 and 205 connected in parallel. Here, even if one of the thyristors 202 and 203 or one of the thyristors 204 and 205 is formed of a diode, the function is the same. AC power supply 20
1 is an input terminal of the thyristor 202 and the thyristor 20
4 input terminals. Smoothing circuit 220
Is a capacitor 20 connected in parallel with the rectifier circuit 210.
6. The full-wave rectifier circuit 210 includes a control circuit 100 for controlling the firing angles of the four thyristors 202 to 205. The control circuit 100 is roughly divided into a two-time integration circuit 120 operating in units of one cycle of the rectified signal.
(The waveform of the output signal is shown in (c) of FIG. 2), and an attenuation circuit 130 that outputs a signal that attenuates with time from a predetermined initial value (the waveform of the output signal is shown in (d) of FIG. 2). When,
The outputs of the twice integration circuit 120 and the attenuation circuit 130 are compared. If the output of the twice integration circuit 120 is large, “Hig
h ”as a firing signal
9 (the waveform of the output signal is shown in FIG. 2 (e)). Hereinafter, the configuration of the control circuit 100 will be described in detail. The AC power supply 101 is turned on at the same timing as the AC power supply 201. The AC power supply 201 may be used as the AC power supply 101. The rectifier circuit 103 is, for example, a well-known rectifier circuit in which two diodes connected in series are connected in parallel, like the rectifier circuit 310 described with reference to FIG. An AC voltage (current) supplied from the AC power supply 101 is full-wave rectified and output. FIG. 2A shows a signal waveform after full-wave rectification flowing to the point P1. The comparator 104 has a predetermined threshold V
The signal after the rectification is converted into a binary digital signal by comparison with th and output. FIG. 2B shows a digital signal flowing to the point P2. The transformer 102 is opposed to the primary coil 102a connected to the AC power supply 101, and has two secondary coils 102b and 102c and rectifier circuits 102d and 102.
e, smoothing circuits 102f and 102g,
01 is transformed, rectified and smoothed to + Vref, -V
ref is output. The rectifier circuits 102d and 102e
For example, a well-known circuit in which two diodes connected in series are connected in parallel, such as the rectifier circuit 310 described with reference to FIG.
Note that + Vref and -Vref are low values that do not require consideration of damage to the smoothing circuits 102f and 102g due to the turning on of the power supply 101. The + Vref obtained from the secondary coil 102b of the transformer 102 is input to the twice integration circuit 120. The two-time integration circuit 120 includes an integration circuit 105 and an integration circuit 106 connected in series. Integration circuit 10
Reference numeral 5 denotes a well-known integration circuit including a resistor 105a, an operational amplifier 105b, and a capacitor 105c, to which an analog switch 105d for short-circuiting the circuit is added. The analog switch 105d is a so-called transistor switch, and switches on when the digital signal output from the comparator 104 is "Low". The output of the integrating circuit 105 is
Is input to The integration circuit 106 is obtained by adding an analog switch 106d for short-circuiting the well-known integration circuit including a resistor 106a, an operational amplifier 106b, and a capacitor 106c. Analog switch 1
06d is a so-called transistor switch, and the digital signal output from the comparator 104 is "Low".
Switch on during FIG. 2C shows an output waveform of the integration circuit 106 flowing at the point P3. On the other hand, the secondary coil 102 of the transformer 102
-Vref obtained from a is Vref (1-e
^{−t / τ} ) (where, Vref: amplitude of the voltage appearing on the secondary side of the transformer 102, e: bottom of natural logarithm, t: elapsed time after power-on, τ: when determined by the resistor 107a and the capacitor 107c) (Which is a constant). The attenuation circuit 130 includes the integration circuit 1
07 and a subtractor 108. Integration circuit 107
Is composed of a resistor 107a, an operational amplifier 107b, and a capacitor 107c. The output of the integration circuit 107 is input to a subtractor 108. The subtracter 108 includes a resistor 108
a, resistor 108b, operational amplifier 108c, and resistor 108
d. The output of the integration circuit 107 is a resistor 108
a. Also, the transformer 10 is connected to the resistor 108b.
2 is applied. In the above configuration, Vref (1-e) is output from the output terminal of the subtractor 108.
^{−t / τ} ) is output. FIG. 2D shows the point P
4 shows a signal waveform flowing in FIG. The output of the integration circuit 106 is input to a positive input terminal of a comparator 109. Also, the subtractor 10
The output of 8 is input to the negative input terminal of the comparator 109. The comparator 109 outputs a “High” thyristor firing signal to each of the thyristors 202 to 205 constituting the full-wave rectifier circuit 210 when the output of the integration circuit 106 is larger than the output of the subtractor 108. (E) of FIG.
Indicates a signal waveform flowing to the point P5. FIG. 2F shows a signal waveform at a point P6 of the full-wave rectifier circuit 210 which operates according to the input thyristor firing signal. FIG. 2G shows a signal waveform flowing to the point P7 of the smoothing circuit 220. As can be seen from this waveform, the control circuit 100 regulates the amount of current flowing from the rectifier circuit 210 to the smoothing circuit 220 immediately after the AC power supplies 101 and 201 are turned on, and gradually controls the capacitor 206 constituting the smoothing circuit 220. Charge. Thus, it is possible to prevent a large charging current from suddenly flowing into the capacitor 206 constituting the smoothing circuit 220 and prevent the capacitor 206 from being damaged. As described above, the firing angle control circuit 1
In the rectifying / smoothing circuit 200 provided with 00, the output amount immediately after power-on can be regulated. As a result, it is possible to prevent an overcurrent generated after the power is turned on from flowing directly into a circuit at a subsequent stage, thereby preventing circuit elements from being damaged. Further, each firing of the thyristor immediately after power-on is gradually increased from the minimum value. As a result, it is possible to prevent an overcurrent generated immediately after the power is turned on from flowing directly into a circuit at a subsequent stage, thereby preventing circuit elements from being damaged. In addition, by employing a configuration in which an ignition signal is generated by an analog circuit without using a digital control circuit such as a computer, a highly reliable and relatively small-scale circuit can be formed. Further, it is possible to prevent the capacitor of the smoothing circuit for smoothing the rectified AC power supply from being damaged by overcurrent. According to the rectifier circuit of the present invention, a rush current to a capacitor constituting a smoothing circuit can be prevented without using a large-sized circuit element such as a relay switch or a current limiting resistor. With the lapse of time, the conduction angle is acceleratedly increased, and the activation can be completed in a short time. [0027]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a configuration diagram of a rectifying / smoothing circuit according to an embodiment. FIG. 2 is a diagram showing signal waveforms flowing to respective points in a rectifying / smoothing circuit. FIG. 3 is a configuration diagram of a conventional rectification / smoothing circuit. FIG. 4 is a configuration diagram of a conventional rectification / smoothing circuit. [Description of Signs] 200 rectifier / smoothing circuit, 210 full-wave rectifier circuit, 2
20 smoothing circuit, 100 firing control circuits, 101
AC power supply, 102 transformer, 103 rectifier circuit, 10
4,109 Comparator, 105, 106, 107 Integrator, 108 Subtractor.

Claims (1)

(57) [Claim 1] A rectifier circuit configured by an on-function controllable switch and rectifying an AC signal supplied from an AC power supply, wherein a rectifier circuit of the AC power supply is provided after the rectifier circuit. In the case where a circuit having a circuit element that is damaged by the flow of all the rectified current immediately after being turned on is provided, at least a predetermined period immediately after turning on the AC power source and a period during which the on function control switch is turned on is controlled. A first circuit that outputs a saw-toothed first signal that increases or decreases at a predetermined cycle, and intersects twice with the first signal output by the first circuit within the cycle. A second circuit for outputting a second signal that decreases or increases in a direction of increasing or decreasing the first signal, and turning on the on-function controllable switch for a gradually longer time; A rectifier circuit comprising: a third circuit that generates a third signal that turns on or off the on-function controllable switch in response to the intersection of the first signal and the second signal.