JPS6323563A - Power supply unit - Google Patents

Abstract

PURPOSE:To produce power for a control circuit efficiently and without suffering any fluctuation of input voltage by using a coil through which an output voltage of a switching regulator circuit is obtained. CONSTITUTION:A winding L2 is added to an inductance element L1 of a switching regulator circuit 1. An input voltage rectified and smoothed by a diode bridge DB and a smoothing capacitor C1 is applied to the inductance element L1 by on/off operation of a switching transistor Q1. A voltage induced in the winding L2 is rectified and smoothed by a diode D2 and a capacitor C2, and is used to energize control circuit.

Description

[Detailed Description of the Invention] [Technical Field 1] The present invention consists of 1. The present invention relates to a power supply device equipped with a switching power supply circuit composed of a high-speed switching element, an inductance component, a smoothing capacitor, and the like.

[Background Art 1] In recent years, so-called switching power supply circuits such as a chikutsuba circuit are increasingly being used in power supply portions in order to downsize electrical equipment. - Basically, this power supply circuit takes commercial power as input and converts it to any DC voltage or AC power of any frequency. Is this switching power supply circuit complicated? A control circuit for high altitude control generally requires several to several dozen DC power supplies. Therefore, it was necessary to prepare a separate power source as a power source for the control circuit. Furthermore, if a transistor, for example, is used as a switching element in a switching power supply circuit, its base drive power may also be supplied by the power supply of the control circuit, and in this case, it is necessary to supply a considerable amount of power to the power supply of the control circuit. .

The following methods were used to obtain power for this control circuit. First, as shown in Fig. 7, commercial power supply AC is rectified by diode bridge DB, and resistor R8l t
This is a method of voltage division using RO2, and the second method is to use a step-down transformer T as shown in FIG. , is used to step down the commercial power supply AC and rectify it by 4L using a diode D01, a smoothing capacitor 001, etc.

However, in the first method, since the voltage is divided by the resistor R61lRo2, the loss becomes abnormally large, and there is a problem that this method is not practical, especially when the power required as the power supply for the control circuit 2 is large. In addition, in the second method, the power capacity,
Alternatively, there is no loss problem, but if the power capacity increases, transformer T. Since the shape of the switching power supply circuit 1 inevitably increases in size and weight, there is a problem that it goes against the purpose of reducing the size and weight by using the switching power supply circuit 1.

Therefore, the conventional circuit shown in FIG. 9 has been conventionally used.

The lighting circuit for the discharge lamp DL includes a diode bridge DB that rectifies the commercial power supply AC, and this diode bridge D.
Switching power supply circuit 1 that converts B output to high frequency voltage
And this switching power supply circuit 1. The control circuit 2 controls the switching of the switching transistor QOl tQ 02, and further includes a bidirectional phase control element Q such as a triac between the commercial power supply AC and the diode bridge DB. , is inserted. The switching power supply circuit 1 includes a current-limiting inductance I, 11 oscillation transformers T1, and a switching transistor Q. It is composed of a so-called L-push-pull inverter made of ItQ02. The above phase control element Q. 30 phase angles are controlled by a control circuit 2. In addition, in order to create a power source for the control circuit 2, the oscillation transformer T has four large turns #XL.

, and these four large volumes #; [L,.

The voltage induced is rectified and smoothed by the diode D o 2 and the capacitor CO3 to create a power source for the control circuit 2 and a base drive power source for the switching transistor Q 0 +t Q O2.

In this conventional circuit, as shown in FIG. 10(a), the voltage Vs of the commercial power supply AC is controlled in phase by a phase control element Q113 as shown in FIG. 10(b), and this phase control voltage is input. Switching transistor Q of switching power supply circuit 1 as voltage Vi. 1lQO2 switches at high speed and generates a high frequency voltage. This switching power supply circuit 1
The voltage corresponding to the turns ratio of the voltage across the 1 large winding #lL, , of the oscillation transformer T is applied to the fourth winding. 4, and this induced voltage (■) is caused by diode D. 2. A control voltage Vcc, which is a DC voltage, is generated by rectification and smoothing by a capacitor C83, and serves as a power source for the control circuit 2 and a switching transistor Q.

Supplied as a base drive power source for IIQO2. In this conventional example, the discharge lamp DL is lit at high frequency, and the phase control element Q is turned on. , the discharge lamp DI- is dimmed by the phase control of the phase control element Q.
A control voltage Vcc is required for controlling 03 and the like. However, since the control voltage Vcc is obtained by dividing the quaternary winding 1-o from the oscillation transformer T, the conventional example 2) described above has less loss and can be made smaller.

By the way, it is desired that the control voltage Vcc used as a power source for the control circuit 2 is a stable constant value. In the above conventional example, if the commercial power supply AC fluctuates or the phase control element Q changes. If the phase angle of 3 exceeds 90 degrees, the fourth winding will occur. The induced voltage ■, induced in , varies significantly. In order to prevent this, it is necessary to set the voltage v4 sufficiently high in advance and add a stabilizing circuit such as a series regiator after rectification and smoothing, which causes the problem of increased cost and increased loss.

Therefore, a conventional circuit shown in FIG. 11 has been devised which improves the above-mentioned points. This is [Utility Model Publication 1986]
-5902, Matsushita Electric, DC-DC Converter. This conventional circuit includes a diode bridge DB and a smoothing capacitor C1 for rectifying and smoothing the commercial power supply AC, and a switching transistor Q0, an inductance element L1, and an inertia diode I)1 for transmitting the rectified and smoothed output.
, and a so-called step-down chopper circuit 4 consisting of a smoothing capacitor C2, and supplies a stable DC voltage vO to the load. The inductance element L is provided with an additional winding L2 electrically coupled with reversed polarity as shown in the figure, and the voltage induced in this additional winding #11x-2 is voltage-doubled and rectified to provide a control voltage Vcc. diode D to create
2*D a and a control voltage generation circuit 3'' consisting of a capacitor C31C1.

In operation, the commercial power supply AC is connected to a diode Brisono DB.
The input voltage Vi obtained by rectification and smoothing by a smoothing capacitor CI is stepped down by a switching power supply circuit 1 constituted by a step-down chopper circuit to create a low output voltage Vo.

This switching power supply circuit obtains a control voltage Vcc by rectifying the voltage induced in the additional winding #i L2 by the current flowing through the inductance element through the diodes D2 and D3 and the capacitors C3 and C. More specifically, when the switching transistor Q1 is on,
The equivalent circuit is shown in FIG. 12(a), where a voltage of (Vi-Vo)/N is induced in the additional winding L2, the capacitor C4 is charged with this voltage via the diode D2, and the switching transistor Q , is off, a voltage of Vo/N is induced in the additional winding L2, and the capacitor C3 is charged with this voltage via the diode D3. Here, inductance element 1=.

and the additional winding #it t-2, the turns ratio is N (=N, /N
2) It is Toshishita. Therefore, the control voltage Vccli' is the sum of the voltages across the capacitors C2 and C1, so Vcc#Vo/N+(Vi-Vo)/N#Vi/N9, which is related only to the input voltage Vi, and the output voltage V .

It is deceptive to create a control voltage that is not related to the control voltage.

However, since this control voltage Vcc is proportional to the input terminal ■1, when the input voltage ■1 fluctuates, the control voltage Vcc(1
The problem was that it fluctuated significantly.

1.Objective of the Invention 1. The present invention has been made in view of the above-mentioned points, and its purpose is to efficiently obtain power for a control circuit and to avoid being affected by fluctuations in input voltage. There is no power supply available.

[Disclosure 1 of the Invention The present invention generally relates to an output voltage Vo of a switching power supply circuit 1.
Focusing on the fact that is constant regardless of the load, that is, a constant voltage output, this output voltage 0 is taken out by a separately provided winding to obtain the control voltage Vcc. Therefore, the control voltage Vec is always a constant voltage proportional to the output voltage Vo without being affected by fluctuations in the input voltage Vi, and the problem α described in the prior art example can be completely eliminated. The reason why the output voltage is constant is that in a normal switching power supply circuit 1, the voltage across the loads 1-7 is detected and the switching transistor Q1 etc. This is because so-called PWM (pulse width control) or V-F (IN wave number conversion) control is performed to control the conduction of the signal.

(Example 1) FIG. 1 and FIG. 2 are diagrams showing an example of the present invention,
In this embodiment, the circuit configuration is substantially the same as that of the double series shown in FIG. 10, so only the features of this embodiment will be explained. In this embodiment, an additional winding I7. is electrically coupled to an inductance element. A voltage proportional to the output voltage Vo is obtained in this embodiment.
The operation will be described below, where the additional winding L2 is wound in the same direction as , the diode D2 and the capacitor C3 are provided, and only rectification and smoothing is performed. When the commercial power supply AC shown in FIG. 2(a) is rectified and smoothed by a diode bridge D11 and a smoothing capacitor C1, the input voltage Vi shown in FIG. 2(1) is obtained. The step-down chopper circuit 4 operates with this input voltage \li, and when the switching transistor Q is turned on as shown in FIG. When transistor Q is off, the output voltage is
0 is generated in the inctus element. However, the voltage generated in the negative direction does not appear at the output of the control voltage generation circuit 3 due to the diode D2, and as shown in FIG. 2(d), a voltage proportional to the output voltage Vo, Vcc# Vo/N
Therefore, even if the input voltage Vi changes, the control voltage Vcc
does not fluctuate, providing a stable control power source. Therefore, volume #i
If the number of turns of L, , , L, 2 is appropriately selected, a separate stabilizing circuit such as a series regulator is not required, and costs and losses can be significantly reduced.

(Embodiment 2) FIGS. 3 and 4 are diagrams showing other embodiments of the present invention, in which the present invention is applied to a so-called buck-boost chopper circuit 5. Although the circuit configuration differs in the insertion location of the inductance element L, etc., the configuration is substantially the same as that of the first embodiment. In operation, as shown in FIGS. 4(c) and 4(d), when the switching transistor Q is turned on, the inctus element 1. The voltage across I becomes -Vi, and when the switching transistor Q1 is off, the voltage across the primary winding becomes 0. Therefore, similarly to the above-mentioned embodiment of tjtJl, the output voltage Vo is connected to the additional winding 1-2 and the diode D.
2. By taking out the capacitor C3, tIfJ
A constant control voltage Vce as shown in FIG. 4(d) can be obtained.

(Embodiment 3) FIGS. 5 and 6 are diagrams showing other embodiments of the present invention, in which a step-up chitappa circuit is used as the switching power supply circuit 1, and a control voltage is generated from the inductance element of this switching power supply circuit 1. Vcc, and the input voltage V
For i, a pulsating voltage obtained by rectifying the commercial power supply AC with a diode bridge DB is used. In this embodiment, the additional winding L2 and the additional winding #ilL have significantly different winding directions.
, a diode D2 and a capacitor C1 for rectifying and smoothing the voltage appearing on the additional winding L2, and a diode D1 and a capacitor D for rectifying and smoothing the voltage appearing on the additional winding.

As shown in FIG. 6(c), the switching transistor Q
When , is on, the voltage across the inctus element L1 is -V
i, and when the switching transistor Q is off, the voltage across the inductance element L1 becomes Vo-Vi. With this voltage, the voltages shown in Figure 6(d) and l(e) are generated in each winding 1-211-3, and by applying these two types of pressure, the control is performed as shown in Figure 6(''). A constant DC voltage is obtained as the voltage Vcc.In this way, in the switching power supply circuit 1 in which a voltage proportional to the output voltage Vo does not appear across the inductance element L, additional windings L2, 1...3 are provided. As a result, a voltage proportional to the output voltage Vo can be obtained.Although addition is performed in the above description, substantially the same result as described above can be obtained by subtraction.

[Effects of the Invention] As described above, the present invention adds one or more windings to the inductance component of a switching power supply circuit, and rectifies and smoothes the voltage induced in the windings in a rectifier and smoothing circuit to obtain an output voltage. Since the power supply for the control circuit is obtained by extracting a voltage proportional to It is possible to obtain stable operation of the switching power supply without fluctuations in the power supply, and because there is no need for a separate stabilization circuit, the number of parts is reduced, resulting in a smaller and cheaper device, which is still more compact than the conventional one. It also has the advantage of low loss, which is a characteristic feature.

[Brief explanation of drawings]

Fig. 1 is a circuit diagram showing one embodiment of the present invention, Fig. 2 is an explanatory diagram of the same operation as above, Fig. 3 is a circuit diagram showing another embodiment of the present invention, and Fig. 4 is an explanatory diagram of the same operation as above. , FIG. 5 is a circuit diagram showing still another embodiment of the present invention, FIG. 6 is an explanatory diagram of the same operation as above, FIGS. 7 and 8 are schematic circuit diagrams showing a conventional example, and FIG. 9 is a circuit diagram showing another embodiment of the present invention. A circuit diagram showing a conventional example, FIG. 10 is an explanatory diagram of the same operation as above, FIG. 11 is a circuit diagram showing another conventional example, and FIG. 12 is a circuit diagram showing a conventional example.
This figure and FIG. 13 are explanatory diagrams of the same operation. 1 is a switching power supply circuit, 2 is a control circuit, 3 is a control voltage generation circuit, Q is a switching transistor, L is an inductance element, L, , , L are additional windings,
D2. D is a diode, and C2 and C3 are capacitors. Agent Patent Attorney Ishi 1) Naocho U'C
:)CL)! ,,+m1. /-one

Claims (3)

[Claims] (1) A switching power supply circuit consisting of a high-speed switching element, an inductance component, a smoothing capacitor, etc.
In a power supply device equipped with a load operated by the output of this switching power supply circuit, and a control circuit that detects the voltage across the load and controls switching of a high-speed switching element to keep the output voltage of the switching power supply circuit constant, One or more windings are added to the inductance component of the power supply circuit, and the voltage induced in this winding is rectified and smoothed by a rectification and smoothing circuit to obtain a voltage proportional to the output voltage to obtain the power supply for the control circuit. A power supply device characterized by comprising: (2) The polarity of the winding added to the inductance element and the diode of the rectifying and smoothing circuit that rectifies the voltage induced in this winding is appropriately selected to extract a voltage proportional to the output voltage. A power supply device according to claim 1, characterized in that: (3) In a switching power supply circuit in which a voltage proportional to the output voltage does not appear across the inductance component, multiple windings are added to the inductance component, and the polarity between the winding and the rectifier diode provided in each of the multiple windings is 3. The power supply device according to claim 2, wherein a voltage proportional to the output voltage is obtained by appropriately selecting the rectified and smoothed output and adjusting each rectified and smoothed output.