JPS61217813A - Power supply circuit - Google Patents

Abstract

PURPOSE:To obtain an inexpensive power supply voltage having the small heating value and a wide range of allowable input voltage, by obtaining the load supply voltage from both ends of a capacitive element and controlling the ON/OFF of a thyristor in response to the load supply voltage and the gate voltage given from a constant voltage circuit. CONSTITUTION:The AC input is rectified by a full-wave rectifier DB consisting of a diode bridge and this rectified output voltage (unstabilized voltage) E1 is supplied to an anode electrode A of a silicon control rectifier SCR 11 via a choke coil L (or a resistor R). Here a cathode electrode K is connected to an output terminal 13 at the positive side as well as to a load output terminal (common terminal) 15 via a capacitor C so that the load supply voltage (stabilized voltage) E2 to be supplied to the load of a power supply circuit is delivered from the electrode K of the SCR 11. Then a gate electrode G is connected to a common terminal via a Zener diode ZD and also to the output side of the rectifier DB and the terminal 13 via resistors R1 and R2 respectively.

Description

[Detailed Description of the Invention] [Technical Field] The present invention relates to a power supply circuit, and in particular, to a power supply circuit that uses a thyristor to perform intermittent rectified output. [Background] Conventionally, stabilization has been performed. A general-purpose series regulator is used as the power source. As an example, as shown in Fig. 3, the stabilized output voltage Eo is compared with the constant voltage E', and the collector-emitter voltage drop Vcε of the regulator transistor is variably controlled in accordance with the difference voltage. The output voltage ε0 is obtained.

Furthermore, three-terminal (input, output, and ground) regulators that are integrated into ICs have recently been widely used. Examples of such ICs include 7800 series (positive output voltage) and 7900 series.
series (negative output voltage).

An extremely highly stable output voltage can be obtained from such a series regulator.In addition, as a publicly known document regarding the above series regulator, Cambridge University 7 Less (OA
MBRIDGE UNIVER8ITY PRES
Paul Horowitz, published by
owitz) and Twinfield Hill (Winf
The Art Off
Electronics (THg ART OF gI,
I would like to mention Chapter 5 of BOTRONIO8).

However, the biggest drawback of such a series regulator is that all voltages exceeding the stabilized output voltage are applied to the regulator, and the voltage in this case generates heat. be. This makes it difficult to take measures for heat dissipation, making the device expensive.

Also, there is a problem in that it is not possible to extract a large amount of stabilized power.

Therefore, although the stabilized output voltage may have some ripple components, it is suitable for stabilizing the average DC voltage, has low heat generation, is inexpensive, and can be used over a wide range of input voltages (not yet used). Known series regulators are not suitable for realizing a power supply circuit that can handle a stable input voltage.

There has been a demand for a stabilized power supply circuit for such applications.

[Purpose of the invention]

The present invention was made in response to such demands, and an object of the present invention is to provide a power supply circuit that generates less heat, is inexpensive, and has a wide punch input voltage range.

〔Example〕

The present invention will be described in detail below based on embodiments shown in the drawings.

FIG. 1 shows an embodiment of the present invention. In the figure, the AC input is rectified by a full-wave rectifier, DB (consisting of a diode bridge), and its rectified output voltage (unregulated voltage) εl is passed through a choke coil L (or resistor R) to a silicon-controlled rectifier (hereinafter referred to as 80R) is supplied to the anode electrode A of 11. From this 5OR11 cathode electrode,
The cathode electrode K is connected to the positive output terminal 13, and one capacitor is connected so that the load supply voltage (stabilized voltage) E2 to be supplied to the load (not shown) of this power supply circuit is output. Negative output terminal (common terminal) 15 via C
It is connected to the.

In order to supply a constant voltage to the gate electrode G of MFT, SOR, 11, this gate electrode Ga is connected to the common terminal via the zener diode zO, and the resistor R1,
It is connected to the output side of the rectifier DB and the positive side output terminal 13 via R2.

The operation of the above-described configuration will be described below with reference to the waveform diagram shown in FIG.

Rectified output voltage E by full-wave rectifier DB! As shown by the dotted line in FIG. 2, the flow is a pulsating flow only on the positive side.

First, consider the case where the load supply voltage E2 occurring between the two output terminals 13.15 is lower than the zener voltage Ez of the zener diode zD, in which case S.

Since the gate electrode G and cathode electrode of R11 are biased in the forward direction, the anode electrode A and cand electrode KrVJFi of the 5CR11 are electrically connected (on state). Therefore, the capacitor CVc is connected to the choke coil L(
Alternatively, the charging current flows through the series resistor R),
The load supply voltage E2d, which is also the voltage across it, increases.

80FNIFi, rectified output voltage E, and load supply voltage E2
At the point where the anode electrode A crosses the
Since the cathode electrodes are reverse biased, their conduction stops (off state) 0. By the way, the discharge state of the charge charged in the capacitor C varies depending on the magnitude of the load current IL. When the load current IL is extremely large, the discharge occurs quickly, and when the load current IL is small, the discharge occurs very slowly.

The charging/discharging cycle of the capacitor C changes depending on the magnitude of the discharge current (load current).

For example, if the load current IL takes a small value IL1, the slope of the drop in the load supply voltage E2 is small, so that the time when it falls below the level of the zener voltage Ez is delayed. Therefore, as shown in the output voltage waveform Ez1 in Fig. 2, 5ORI 1 is generated only after the full-wave rectified waveform has been skipped over two peaks.
gate electrode G.

The canned electrodes are forward biased and turned on.

Next, when the load current IL takes a large value IL2,
At that time, the decreasing slope of the load supply voltage E22 is large, and the next pulsating wave does not jump over the full-wave rectified waveform even once.
The gate electrode G and cathode electrode of the OR 11 are forward biased and turned on.

Furthermore, if the load current IL is a medium value IL3 (ILI<IL
3<1L2), the slope of decrease of the load supply voltage E23 is 4. , IL, and IL2, and after jumping over the full-wave rectified waveform, 5CR1
A forward bias is applied between the gate electrode G of No. 1 and the canned electrode G, and the forward bias is turned on.

In this way, the charge/discharge cycle of the capacitor C becomes variable depending on the load current IL. Its output, the load supply voltage E2, is always maintained at a running value close to the zener voltage Ez of the zener diode zO. This load supply voltage E
2 can be suppressed to a sufficiently low level by sufficiently increasing the capacitance of the capacitor C.

In other words, the ripple at the regulated output voltage is large compared to a series regulator, but depending on the magnitude of the load current,
Since only the number of conduction times of the FL changes, voltage loss and heat loss are essentially small. Here, the number of conduction times of the SCR depends on the half period of the AC input to be full-wave rectified.

Applications of the power supply circuit described above include battery charging devices, stabilized power supply devices for relays, power supply devices for stud welds, and the like.

In the above-described embodiments, the rectifier is used for full-wave rectification, but it may be used for half-wave rectification. In that case, the number of times the SOR conducts depends on the period of the AC input.

Further, although the constant voltage supplied to the gate electrode G of 8CR11 is the Zener voltage Ez, other constant voltage supply means may be used.

Further, although the output voltage with positive polarity is generated, the circuit may be configured so that a negative output voltage is applied to the load, in which case the polarity is reversed, but the circuit operation is the same.

〔Effect of the invention〕

As described in detail above, according to the present invention, it is possible to realize a power supply circuit that generates less heat, is inexpensive, can handle a wide range of voltages, and can supply stabilized DC voltage.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing the configuration of a power supply circuit according to an embodiment of the present invention, Fig. 2 is an input and output waveform diagram for explaining the circuit of Fig. 1, and Fig. 3 is a conventionally known series regulator. FIG. 2 is a block diagram showing the configuration of FIG. 11...Silicon controlled rectifier (SOR)
13.15... Output terminal DB...
... Full wave rectifier ZD ... - ... Zener diode C ...
...... Capacitor E] ...... Rectified output voltage E2 ...... Stabilized DC voltage IL ...
...Load current y3tse; -PV2 @Figure 7 Figure 2 Figure 3

Claims (1)

[Claims] 1) A rectified output of AC input, a constant voltage circuit, and a capacitive element are connected to the anode, gate, and cathode of the thyristor, respectively, so that the load supply voltage is obtained from both ends of the capacitive element. . A power supply circuit configured to control on/off of the thyristor according to the load supply voltage and the gate voltage from the constant voltage circuit. 2) The power supply circuit according to claim 1, wherein the constant voltage circuit is constituted by a Zener diode, and the Zener voltage is used as the gate voltage. 3) The power supply circuit according to claim 1, wherein the capacitive element is a capacitor. 4) the load supply voltage is low with respect to the gate voltage;
2. The power supply circuit according to claim 1, wherein the thyristor is configured to be turned on and off depending on the voltage.