JPH114579A - Power supply - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To compare an output voltage detection value from a sense input with a preset reference voltage value and control an input-side switching operation based on the comparison result to regulate an output voltage. By connecting a plurality of switching regulator type switching power supplies in series and connecting outputs in parallel, the input voltage and output current are balanced in a power supply device with an increased input withstand voltage.
It enables high-density mounting of parts and cost reduction. SOLUTION: A plurality of switching power supplies 100 and 20 are provided.
An average value of each input voltage of 0, 300 is obtained, and a difference signal between the average value and each input voltage of the plurality of switching power supplies is used as a sense input Sp1, Sp2, output voltage output of the plurality of switching power supplies. A plurality of feedback means 118 to 122, 218 for individually feeding back to Sp3.
To 222 and 318 to 322.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power supply unit for realizing a high withstand voltage input by using a plurality of switching regulator type power supply units with a low withstand voltage input.

[0002]

2. Description of the Related Art Conventionally, a DC power supply having a commercial AC power supply as input is generally of a 100 V input or 200 V input. In order to realize a DC power supply having a high withstand voltage input of 400 V or more, the following method can be considered. First
Is a method of lowering the input voltage by inserting a transformer on the input side. However, this method has a problem that the transformer is large due to the low input frequency and high-density mounting cannot be performed. As a second method, 400
One example is to develop a new power supply device with a custom specification of an input of V or more. However, this method requires components having high withstand voltage, such as internal switching transistors and diodes. Components with high withstand voltage usually have large loss and large volume, making high-density mounting impossible. In addition, since these components are not generally used in large quantities, the cost increases and the supply of components may not be stable. Problem. As a third method, the conventional 100
A method is conceivable in which a plurality of V input or 200 V input power supply devices are prepared, and these inputs are connected in series to increase the input withstand voltage equivalently. However, this method has a problem in circuit characteristics that the voltage of the input connected in series and the current of the output connected in parallel are not constant and become unbalanced.

FIG. 3 is a circuit diagram showing a conventional power supply device in which two switching regulator type power supply devices are prepared and the above-mentioned third method is applied, that is, their inputs are connected in series. 4 and 5 are signal waveform diagrams for explaining the operation of the conventional power supply device shown in FIG. 3, and FIG. 4 is a diagram showing input waveforms to the PWM control circuits 719 and 819 in FIG. FIG. 4 is a diagram showing a fluctuation waveform of the input voltage with respect to time in FIG. 3.

As shown in FIG. 3, one end of an AC power supply (commercial AC power supply) 78 has a positive input I of a switching power supply 700.
The other end is connected to the negative input In8 of the switching power supply 800 at the other end. Further, the negative input In7 of the switching power supply 700 is connected to the positive input Ip8 of the switching power supply 800, and the switching power supply 700 and the switching power supply 800
Are connected in series. Since the switching power supplies 700 and 800 have the same configuration (the same input withstand voltage) as described later, the input withstand voltage is twice as large as the input withstand voltage of one switching power supply 700 or 800 (for an AC power supply having twice the voltage). ).

The positive output Fp7 and the positive sense input Sp7 of the switching power supply 700, and the positive output Fp8 and the positive sense input Sp8 of the switching power supply 800 are connected to each other so that the DC load 7
9, a negative output Fn7 and a negative sense input Sn7 of the switching power supply 700, and a negative output Fn8 and a negative sense input Sn8 of the switching power supply 800 are connected to each other and connected to the other end of the DC load 79, The outputs of the switching power supply 700 and the switching power supply 800 are connected in parallel.

The switching power supply 700 includes a diode 7
02 to 705, an input smoothing capacitor 706, a transformer 707, a transistor 70
8, output current detecting transformer 709, output current detector 7
20, rectifier diode 710, commutation diode 711,
Choke coil 712, output smoothing capacitor 713, sense input voltage dividing resistors 714 to 716, reference voltage source 717,
This is a PWM-controlled forward converter type switching regulator power supply composed of an error amplifier 718 and a PWM control circuit 719. The switching power supply 800 is also a switching power supply having the same configuration as the switching power supply 700. In this case, reference numerals “7 ??”, “??? 7”, and “?? 7” (??
Represents an arbitrary numeral and? Represents an arbitrary alphabetic character.) "7" corresponds to "8".

In the above-described conventional power supply device, as a method of outputting a constant voltage value with respect to a constant input voltage, a switching regulator type power supply device in which a signal for increasing or decreasing the output voltage is fed back to transistors 708 and 808 that perform switching operation. Typical circuit (for example,
A method similar to that shown in FIG. As a method of balancing output currents, a method is used in which a difference between each output current and an average value of each output current is obtained, and this difference is fed back to transistors 708 and 808 that perform a switching operation (for example, Japanese Unexamined Patent Application Publication No. 195370).

[0008]

However, the above-mentioned conventional apparatus has the following problems. First, in the circuit configuration of the conventional device shown in FIG. 3, consider the operation when the input side is connected in series without connecting the common signal line Lci78 for balancing the output current and the output side is connected in parallel. View. As an example, as shown in FIG. 4, the output voltage reference values Vr7, Vr of the two switching power supplies 700, 800
A case will be described in which there is an error in the setting of r8, and the sense voltages Vor7, Vor8 of the output voltages Vo7, Vo8 become voltages between the set values of the output voltage reference values Vr7, Vr8 at time t = 0.

In this case, the switching power supply 700 extends the conduction period of the transistor 708 to increase the output voltage Vo7, increases the current Iit7, and increases the output current Io7.
It works in the direction of increasing. On the other hand, the switching power supply 800 operates in the direction of shortening the conduction period of the transistor 808 and decreasing the current Iit8 to decrease the output current Io8 in order to decrease the output voltage Vo8. Therefore, the capacitor 706 discharges and the charging voltage Vic7 decreases, and the capacitor 806 charges and the charging voltage Vic8 increases. Therefore, the input voltage Vi7 decreases and the input voltage Vi8 increases, whereby the input voltages Vi7 and Vi8 enter an unbalanced state as shown in FIG.

In this case, the output current Io7 increases, but the output current Io8 decreases. Therefore, the load current Io78 becomes substantially constant, and the output voltages Vo7 and Vo8 hardly change. Therefore, the sense voltages Vor7, Vor8 and the output voltage reference value Vr7,
Since the potential difference from Vr8 hardly changes, the input voltage Vi7
Continues to decrease, and the input voltage Vi8 continues to increase, resulting in a large imbalance in the input voltage. When the input voltage is unbalanced, the input power is unbalanced, so that the output current is unbalanced.

The voltage condition shown in FIG. 4 shows an example in which the above-mentioned phenomenon occurs, and Vor7 <Vr7 and Vor8> in the drawing.
The above-mentioned phenomenon occurs when the condition of Vr8 or the condition of Vor8> Vr8 and the condition of Vor8 <Vr8 are satisfied. Output voltage reference values Vr7 and Vr8
Usually has some error, and the sense voltage Vor7,
Since Vor8 is near the output voltage reference values Vr7 and Vr8, the state easily satisfies the above-mentioned voltage condition, and the above-mentioned phenomenon is likely to occur.

Next, in the circuit configuration of the conventional device shown in FIG.
Considering a method similar to the method described in Japanese Patent No. 95370, that is, an operation when the common signal line Lci78 is connected between the current balance terminals Ci7 and Ci8, the current balance function does not work in this case as well. . The cause will be described below.

The conventional device shown in FIG. 3 includes a current balance circuit composed of an output current detection transformer 709 and an output current detector 720 in order to balance currents.
By connecting the current balance terminals Ci7 and Ci8 with a common signal line Lci78, a difference voltage between the current detection voltages Vis7 and Vis8 proportional to the output currents Io7 and Io8 and the average value of the current detection voltages Vis7 and Vis8 is detected. This is applied to the sense voltage Vor7,
Feedback to Vor8 to balance the current. In this case, under the condition of Vor7 <Vr7 and Vor8> Vr8, if the current Iit7 is to be increased, negative feedback is applied and the current Iit7 is temporarily operated in a direction to reduce the increase. However, at this time, since the discharge of the capacitor 706 proceeds, the voltage of the charging current Vic7 decreases, the current of the output current Io7 decreases, and conversely, Iit7 increases.
In the direction of increasing the conduction time.
Therefore, the discharge of the capacitor 706 progresses and works in a direction to unbalance the input current and the output current. Although the case where the input sides of two power supplies (700, 800) are connected in series has been described above, the same can be said for the case where the input sides of an arbitrary number of power supplies are connected in series.

As described above, in the conventional apparatus shown in FIG.
There is a problem that an unbalanced state of the input voltage and the output current cannot be avoided. This eliminates the need to insert a large transformer on the input side or use high breakdown voltage components such as switching transistors and diodes inside the device, enabling high-density mounting of components and cost reduction. In spite of the advantage of this, it has not been possible to actually use it, and there has been a demand for improvement in this regard.

An object of the present invention is to realize a switching power supply having a high input withstand voltage by using a switching power supply having a low input withstand voltage without imbalance of an input voltage and an output current. It is an object of the present invention to provide a power supply device that can be implemented.

[0016]

SUMMARY OF THE INVENTION An object of the present invention is to compare an output voltage detection value from a sense input with a preset reference voltage value, and control the switching operation on the input side based on the comparison result. In a power supply device in which a plurality of switching regulator type switching power supplies for performing regulation, an input is connected in series and an output is connected in parallel, an average value of respective input voltages of the plurality of switching power supplies is obtained, A difference signal between the average value and the individual input voltages of the plurality of switching power supplies,
This is achieved by providing a plurality of feedback means for individually feeding back the output voltage sense inputs of the plurality of switching power supplies.

Each feedback means calculates an average value of the input voltage of the switching power supply, and feeds back a difference signal between the average value and the input voltage of the switching power supply to a sense input of an output voltage of the switching power supply. As a result, control is performed so that the value of the input voltage of each switching power supply becomes equal to the average value of the input voltages. Therefore, the input voltage of each switching power supply becomes equal, and as a result, the output current becomes equal, and both the input voltage and the output current are balanced. Here, in the device of the present invention, there is no need to insert a large-sized transformer on the input side or use high-withstand voltage components such as switching transistors and diodes inside the device. And cost reduction is possible.

[0018]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a circuit diagram showing one embodiment of a power supply device according to the present invention.

In FIG. 1, one end of an AC power supply (commercial AC power supply) 13 has a positive input I of a switching power supply 100.
The other end is connected to the negative input In3 of the switching power supply 300 at the other end. Further, the negative input In1 of the switching power supply 100 is connected to the positive input Ip2 of the switching power supply 200, and the negative input In2 of the switching power supply 200 is connected to the positive input Ip3 of the switching power supply 300. That is, the switching power supply 100, the switching power supply 200
The input of the switching power supply 300 is connected in series. Here, the switching power supplies 100, 200, 300
Have the same configuration (same input withstand voltage) as described later, so that one switching power supply 100, 200 or 300
Is three times the input withstand voltage (for an AC power supply with three times the voltage).

The positive output Fp1 of the switching power supply 100,
The positive output Fp2 of the switching power supply 200 and the positive output Fp3 of the switching power supply 300 are collectively connected to one end of the DC load 14. Also, the positive sense input Sp
1. The positive sense input Sp2 and the positive sense input Sp3 are also connected to one end of the DC load 14 via resistors 117, 217 and 317, respectively. Further, the switching power supply 100
Output Fn1, negative sense input Sn1, switching power supply 2
The negative output Fn2 and negative sense input Sn2 of 00 and the negative output Fn3 and negative sense input Sn3 of the switching power supply 300 are collectively connected and connected to the other end of the DC load 14. That is, the switching power supply 100, the switching power supply 200
The output of the switching power supply 300 is connected in parallel.

The switching power supply 100 includes an input rectifier circuit 101 including diodes 102 to 105, an input smoothing capacitor 106, a transformer 107, a transistor 1
08, rectifier diode 109, commutation diode 123,
Choke coil 110, output smoothing capacitor 111, sense input voltage dividing resistors 115 and 116, reference voltage source 114,
It is a switching converter type power supply of a PWM-controlled forward converter type configured by an error amplifier 113 and a PWM control circuit 112. The switching power supplies 200 and 300 also have the same configuration as the switching power supply 100. In the figures, 220 and 320 are input voltage detecting transformers, 221 and 321 are switching transistors, and 222 and 322 are switching circuits.

Here, the switching power supplies 100, 2
As can be seen from comparison with FIG. 3, reference numerals 00 and 300 denote circuit portions for balancing currents from switching power supplies 700 and 800 of the conventional device (output current detecting transformer 70, respectively).
9, the output current detector 720). Therefore, the switching power supplies 100, 200,
The operation of the switching power supply 300 is the same as that of the switching power supplies 700 and 800 of the conventional device, except for the operation of the circuit portion for balancing the current in the conventional device, and thus the description thereof is omitted. In FIG. 1, Vo1, Vo2, Vo3 are output voltages of the switching power supplies 100, 200, 300, Vr1 is an output voltage reference value of the switching power supply 100, and Vor1 is a sense voltage of the output voltage Vo1.

In the apparatus of the present invention, the input voltage (AC voltage) Vi1 of the switching power supply 100 is switched by the switching transistor 121 by the switching circuit 122, and the input Isp1 of the input voltage detector 119 is input via the input voltage detecting transformer 120. , Isn1 and
Sense voltage (DC voltage) Vvs1 proportional to input voltage Vi1
Is detected between both ends of the outputs Osp1 and Osn1 of the input voltage detector 119. Similarly, the input voltage (AC voltage) Vi2 of the switching power supply 200 is set as the sense voltage (DC voltage) Vvs2 proportional to the input voltage Vi2, and the input voltage detector 21
9, the input voltage (AC voltage) Vi3 of the switching power supply 300 is detected as a sense voltage (DC voltage) Vvs3 proportional to the input voltage Vi3, and the output Osp3 of the input voltage detector 319 is detected. , Osn3 are detected between both ends. The input voltage detectors 119, 219, 3
One of the outputs Osn1, Osn2, Osn3 is connected in common, and the other output Osp1, Osp2, Osp3 is connected to a resistor 118,2.
18 and 318, the respective positive sense inputs Sp1, S
It is connected to p2 and Sp3.

Here, each switching power supply 100, 20
Circuits from the positive inputs Ip1, Ip2, Ip3 of 0,300 to the respective positive sense inputs Sp1, Sp2, Sp3 (from the switching transistors 121, 221 and 321 to the resistors 118 and 21).
8 and 318) are connected to the respective positive sense inputs Sp1 and Sp.
2, Sp3 constitutes a circuit for feeding back a value proportional to the difference between the average value Vim of the input voltages Vi1, Vi2, Vi3 and the input voltages Vi1, Vi2, Vi3.

Therefore, each positive sense input Sp1, Sp2,
In Sp3, the average value Vim of the input voltages Vi1, Vi2, and Vi3 and the respective input voltages Vi1 and Vi1, via the resistors 118, 218, and 318.
A value proportional to the difference between Vi2 and Vi3 is fed back, and the direction of the feedback is determined by the input voltages Vi1 and Vi3.
Vi2 and Vi3 are average values Vim of input voltages Vi1, Vi2 and Vi3.
Direction. As a result, the input voltages Vi1, Vi2, and Vi3 become three switching power supplies 100, 2
If the values match at 00 and 300, the input currents Ii12 are common and the input powers match, and the output currents Io1, Io2, and Io3 also substantially match. That is, the input voltage and the output current are both balanced. The case where the inputs of three switching power supplies 100, 200, and 300 are connected in series has been described above. However, the same operation is performed when the input of two or four or more switching power supplies is connected in series. The result (the effect of balancing the input voltage and the output current) is obtained.

FIG. 2 is a circuit diagram showing another embodiment of the power supply device according to the present invention. In FIG. 2, a switching power supply 40 is connected to one end of an AC power supply (commercial AC power supply) 46.
The positive input Ip4 of 0 is connected to the negative input In6 of the switching power supply 600 at the other end. Further, the negative input In4 of the switching power supply 400 is connected to the positive input Ip5 of the switching power supply 500, and the negative input In5 of the switching power supply 500 is connected.
Is connected to the positive input Ip6 of the switching power supply 600. That is, the inputs of the switching power supply 400, the switching power supply 500, and the switching power supply 600 are connected in series. Here, switching power supplies 400 and 50
0 and 600 have the same configuration (same input withstand voltage) as described later, so that one switching power supply 400, 50
The input withstand voltage is three times the input withstand voltage of 0 or 600 (for an AC power supply of three times the voltage).

The positive output Fp4 of the switching power supply 400, the positive sense input Sp4, and the positive output Fp5 of the switching power supply 500
The positive sense input Sp5, the positive output Fp6 of the switching power supply 600, and the positive sense input Sp6 are collectively connected to one end of the DC load 47. The negative output Fn4 and negative sense input Sn4 of the switching power supply 400, the negative output Fn5 and negative sense input Sn5 of the switching power supply 500, and the negative output Fn6 and negative sense input Sn6 of the switching power supply 600 are:
They are collectively connected and connected to the other end of the DC load 47.
That is, the outputs of the switching power supplies 400, 500 and 600 are connected in parallel.

The switching power supply 400 includes an input rectifier circuit 401 including diodes 402 to 405, an input smoothing capacitor 406, a transformer 411, a transistor 4
12, rectifier diode 421, commutation diode 422,
Choke coil 423, output smoothing capacitor 424, sense input voltage dividing resistors 415-417, reference voltage source 418,
Error amplifier 414, PWM control circuit 413, switching circuit 408, switching transistor 407, input voltage detection transformer 409, input voltage detector 410, output current detection transformer 419, and output current detector 420
This is a switching converter type power supply of a forward converter system based on PWM control, which is configured by: Switching power supplies 500 and 600 have the same configuration as switching power supply 400 described above. In FIG. 2, Vo
4, Vo5, Vo6 are switching power supplies 400, 500, 6
Vr4 is an output voltage reference value of the switching power supply 400, and Vor4 is a sense voltage of the output voltage Vo4.

That is, here, (1) the switching transistor 121, the switching circuit 122, the input voltage detecting transformer 120, and the input voltage detector 119 which are external circuits in the switching power supply 100 shown in FIG.
Is incorporated in the switching power supply 400 (in the circuit unit of the switching power supply 400) as shown by 407, 408, 409 and 410 in FIG.
(2) The sense voltage Vvs4 corresponding to the sense voltage Vvs1 in FIG. 1 is generated and detected from the voltage after rectification and smoothing of the input voltage of the switching power supply, that is, the voltage across the input smoothing capacitor 406, and (3) Switching. Power supply 4
Even when the input of the switching power supply 400, the switching power supply 500, and the input of the switching power supply 600 are connected in parallel by providing an input current detection transformer 419 and an input current detector 420 for balancing the output current inside The difference from the power supply device illustrated in FIG. 1 is that the terminals Ci4 to Ci6 are connected to enable the output current to be balanced.

The above (1) to (3) are the same for the switching power supplies 500 and 600. The other parts of the power supply device shown in FIG. 2 are configured equivalently to FIG. 1, and operate similarly to the power supply device illustrated in FIG.

In each of the above embodiments, the case where the inputs of three switching power supplies are connected in series has been described. However, the inputs of two or more switching power supplies may be connected in series.

[0032]

As described above, according to the present invention, it is possible to realize a switching power supply having a high input withstand voltage by using a switching power supply having a low input withstand voltage without imbalance in input voltage and output current. There is no need to insert a large transformer on the input side or use a high-withstand voltage component inside the device. Can be provided.

[Brief description of the drawings]

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

FIG. 2 is a circuit diagram showing another embodiment of the device of the present invention.

FIG. 3 is a circuit diagram showing a conventional device.

FIG. 4 is a signal waveform diagram for explaining each operation of the conventional device.

FIG. 5 is a signal waveform diagram for explaining each operation of the conventional device.

[Explanation of symbols]

13: AC power supply (commercial AC power supply), 14: DC load, 1
00, 200, 300 switching power supply, 101 input rectifier circuit, 102 to 105 diode, 106 input smoothing capacitor, 107 transformer, 108 transistor, 109 rectifier diode, 110 choke coil, 111 output smoothing capacitor , 112 PWM control circuit, 113 error amplifier, 114 reference voltage source, 1
15, 116 ... sense input voltage dividing resistors, 117, 118,
217, 218, 317, 318 ... resistance, 119, 21
9,319 ... input voltage detector, 120,220,320
... Transformers for input voltage detection, 121, 221 and 321
Switching transistors, 122, 222, 322 ...
Switching circuit, 123 ... commutation diode.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Junichi Taguri 810 Shimoimaizumi, Ebina-shi, Kanagawa In the Office Systems Division of Hitachi, Ltd.

Claims (3)

[Claims] 1. A switching regulator type that compares an output voltage detection value from a sense input with a preset reference voltage value and controls an input-side switching operation based on the comparison result to regulate an output voltage. In a power supply device in which a plurality of switching power supplies are connected in series and outputs are connected in parallel, an average value of input voltages of the plurality of switching power supplies is obtained, and the average value and the average A power supply device comprising a plurality of feedback means for individually feeding back a difference signal from each input voltage of a switching power supply to sense inputs of output voltages of the plurality of switching power supplies. 2. The power supply device according to claim 1, wherein each feedback means is incorporated in a circuit unit of each switching power supply, and a common signal terminal of each switching power supply is provided outside the circuit unit. 3. A switching regulator type which compares an output voltage detection value from a sense input with a preset reference voltage value and controls an input side switching operation based on the comparison result to regulate an output voltage. In a power supply device in which a plurality of switching power supplies are connected in series and an output is connected in parallel, an average value of input voltage rectified and smoothed voltages of the plurality of switching power supplies is obtained, and the average value is obtained. A power supply, comprising: a plurality of feedback means for individually feeding back a difference signal between a value and each input voltage of the plurality of switching power supplies to a sense input of an output voltage of the plurality of switching power supplies. apparatus.