JP2001037210A - Dc power source unit connecting a plurality of dc power source circuit in parallel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a DC power source unit capable of easily and excellently balancing output currents of a plurality of DC power source circuits. SOLUTION: DC/DC converters 11, 12 are connected in parallel. Voltage of a common load 13 is detected and compared with a reference voltage, and a voltage control signal Ve composed of an error signal is formed. Currents 11, 12 of the respective converters 11, 12 are detected, and a first and a second unbalance values Va, Vb are detected with an unbalance detecting means 22. Ve-Va which is difference between the first unbalance value Va and the output voltage control signal Ve, and Ve-Vb which is difference between the second unbalance value Vb and the output voltage control signal Ve are detected, and a first and a second corrected output voltage controlling signals Ve1, Ve2 are formed. PWM pulses are formed on the basis of the first and the second corrected output voltage controlling signals Ve1, Ve2, and the first and the second DC/DC converters 11, 12 are controlled.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a DC power supply device in which a plurality of DC power supply circuits such as a DC / DC converter and a switching rectifier circuit are connected in parallel.

[0002]

2. Description of the Related Art A conventional DC power supply device in which a plurality of DC power supply circuits are connected in parallel in order to cope with an increase in capacity, comprises, for example, first and second DC / DC converters 1, 2 as shown in FIG. And these control circuits 3, 4 and the first and second
, And output terminals 8 and 9 for connecting a load 7. First and second DC /
The DC converters 1 and 2 are connected to common output terminals 8 and 9 via diodes 5 and 6.

[0003]

By the way, in the DC power supply of FIG. 1, the output voltage varies due to the variation in the characteristics of the elements constituting the converters 1 and 2, and a large amount of current flows to one of the converters. Sometimes. If the current is biased in one converter, it may be destroyed. Therefore, in consideration of this, generally, the capacity of the converters 1 and 2 is given a margin. As a result, the DC power supply was inevitably increased in size. Further, in the DC power supply device of FIG. 1, power loss occurs due to the backflow preventing diodes 5 and 6, thereby preventing high efficiency.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a DC power supply capable of easily and favorably balancing output currents of a plurality of DC power supply circuits. Another object of the present invention is to provide a DC power supply that can improve efficiency.

[0005]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems and to achieve the above-mentioned objects, the present invention has a control element for controlling an output voltage, and has a control element connected in parallel with each other so as to supply power to a common load. A plurality of connected DC power supply circuits,
A plurality of current detection means for detecting output currents of the plurality of DC power supply circuits, an output voltage detection means for detecting a voltage between terminals of the load, a reference voltage means,
Output voltage control signal forming means for forming a voltage control signal corresponding to a difference between an output voltage detection value obtained from the output voltage detection means and a reference voltage value provided by the reference voltage means; An unbalance detection unit that outputs a plurality of unbalance detection values indicating an unbalance of output currents of the plurality of DC power supply circuits based on an output of the plurality of DC power supply circuits, and cancels the imbalance of output currents of the plurality of DC power supply circuits. Correcting the voltage control signal so as to generate a plurality of corrected output voltage control signals each having a value corresponding to a difference between the plurality of unbalanced detection values and the voltage control signal. Voltage control signal forming means, and a control element for forming a control signal for controlling a control element of the plurality of DC power supply circuits based on the plurality of corrected output voltage control signals Those related to the direct current power supply device having a control signal forming means.

When the first and second DC power supply circuits are connected in parallel, it is desirable that the unbalance detecting means is constituted by first and second subtracting means. In addition, an average value of a plurality of detected current values can be obtained and an imbalance can be detected using the average value as a reference signal. Further, it is desirable not to provide a backflow preventing diode as described in claim 4.

[0007]

According to the present invention, the output voltage control signals are controlled based on the unbalanced detection values of the output currents of the plurality of DC power supply circuits to form a plurality of corrected output voltage control signals. , The control element of each DC power supply circuit is controlled, so that imbalance can be easily reduced with a relatively simple configuration. According to the second aspect of the present invention, the unbalance detection value can be easily obtained by the first and second subtraction means. According to the third aspect of the present invention, it is possible to accurately obtain an unbalance detection value. According to the fourth aspect of the present invention, since no reverse current blocking diode is provided, no power loss occurs due to this.
Efficiency can be improved.

[0008]

Embodiments and Examples Next, embodiments and examples of the present invention will be described with reference to FIGS.

[0009]

First Embodiment A DC power supply according to a first embodiment shown in FIG. 2 has a common configuration with first and second DC / DC converters 11 and 12 as first and second DC power supply circuits. Load 1
3 and a pair of output terminals 14 and 15 and currents I1 and I2 flowing through the first and second converters 11 and 12, respectively.
And second current detectors 16 and 17 for detecting
And a control circuit 18.

The output terminals of the first and second converters 11 and 12 are connected to a common pair of output terminals 14 and 15 without passing through a backflow preventing diode. Therefore, the first and second converters 11 and 12 are connected to each other in parallel. The first and second converters 11 and 12 have substantially the same configuration. For example, as shown in FIG. 3, a primary winding of a transformer Tr connected between one end and the other end of a DC power supply E1. Line N1 and switch Q as control element
1 comprises a series circuit, an output rectifier diode D connected to the secondary winding N2 of the transformer Tr, and a smoothing capacitor C. In FIG. 3, the transformer T is turned on while the switch Q1 is on.
Magnetic energy is accumulated in the core of the transformer Tr, and the diode D conducts based on the emission of the magnetic energy of the core of the transformer Tr during the off period of the switch Q1, and a charging current flows through the smoothing capacitor C. The voltage of the capacitor C is adjusted by the ON time width or the duty ratio of the switch Q1. Incidentally, the DC power supply E1 can be constituted by a rectifier circuit, a battery or the like.
Further, one DC power supply E1 can be shared by the first and second converters 11 and 12.

The control circuit 18 is roughly divided into voltage detecting resistors 19a and 19b as output voltage detecting means, a reference voltage source 20 as reference voltage means, an error amplifier 21 as output voltage control signal forming means, and an unbalanced circuit. Detecting means 2
2, a correction output voltage control signal forming means 23, and a control element control signal forming means 24.

The output voltage detecting resistors 19a and 19b detect an output voltage between the output terminals 14 and 15, and output a corresponding detection voltage V0 from a voltage dividing point 19c. The positive input terminal of the voltage control signal forming error amplifier 21 is connected to the voltage dividing point 19 c, and the negative input terminal is connected to the reference voltage source 20. Accordingly, the output voltage control signal Ve corresponding to the difference between the detection voltage V0 and the reference voltage Vr is obtained from the error amplifier 21.

The unbalance detecting means 22 comprises first and second subtractors 25 and 26. The negative input terminal of the first subtractor 25 is connected to the output line 16a of the first current detector 16, and the positive input terminal is connected to the output line 17a of the second current detector 17. The negative input terminal of the second subtractor 26 is connected to the output line 17a of the second current detector 17, and the positive input terminal is connected to the output line 16a of the first current detector 16. The first
And the second current detectors 16 and 17 output first and second current detection voltages V1 and V2 corresponding to the first and second output currents I1 and I2. Therefore, the first subtractor 25 performs the operation of V2 -V1, and the first subtracter 25 corresponding to the operation result
Is output. The second subtractor 26 calculates V1 -V2 and outputs a second unbalance detection value Vb corresponding to the calculation result.

FIG. 4 shows first and second subtractors 25 and 26.
Is shown in more detail. The first and second subtractors 25 and 26 have the same configuration as each other, and comprise a well-known differential amplifier composed of an operational amplifier A1 and four resistors R1, R2, R3 and R4.

The correction output voltage control signal forming means 23 comprises third and fourth subtracters 27 and 28. Third and fourth
The positive input terminals of the subtracters 27 and 28 are connected to the error amplifier 21, respectively, and their negative input terminals are connected to the first and second subtracters 25 and 26. Accordingly, the third and fourth subtractors 27 and 28 are the first and second subtractors 27 and 28 which are obtained by subtracting the first and second unbalanced detection values Va and Vb from the output voltage control signal Ve and having the values Ve-Va and Ve-Vb. 2 output the corrected output voltage control signals Ve1 and Ve2. FIG. 5 shows the third
And details of the fourth subtractors 27 and 28. The third and fourth subtracters 27 and 28 are identical to each other, and are composed of a well-known differential amplifier including an operational amplifier A2 and resistors R5 and R6.

The control element control signal forming means 24 comprises first and second control signal forming circuits 29 and 30, and third and fourth subtracters 27 and 28 and first and second converters 11 and 12. And the control terminal of the switch Q1. First and second control signal forming circuits 29, 30
Are substantially identical to each other, and include a sawtooth generator 31 and a comparator 32 as shown in principle in FIG. The comparator 32 compares the first and second corrected output voltage control signals Ve1 and Ve2 with the sawtooth voltage Vt as shown in FIG. 6A, and outputs a PWM pulse shown in FIG. 6B. ,
This is sent to the switch Q1 of the converters 11 and 12. The sawtooth generator 31 generates a triangular wave voltage at a repetition frequency of, for example, 20 kHz. Note that one sawtooth generator 31 can be shared by the first and second control signal forming circuits 29 and 30. The comparator 32 outputs the corrected output voltage control signals Ve1, Ve2
A high-level PWM pulse is generated when the sawtooth voltage Vt is higher than this voltage level. The switch Q1 of the converters 11 and 12 is turned on during the high level pulse shown in FIG.

[0017]

[Operation] The output currents I1, I2 of the first and second converters 11, 12 are the same, and the current detection voltages V1, V2
2 are the same, the first and second subtractors 25, 26
, Ie, the first and second unbalance detection values Va, V
b is zero. Therefore, the third and fourth subtractors 2
The outputs of 7 and 28 are the first and second unbalance detection values V
The first and second corrected output voltage control signals Ve1 and Ve2 become independent of the output voltage control signal Ve obtained from the error amplifier 21. Accordingly, PWM pulses are output from the control signal forming circuits 29 and 30 at the same duty ratio, and the first and second converters 11 and 12 are driven under the same conditions.

On the other hand, for example, the first converter 11
Is the output current I2 of the second converter 12.
Is larger than the first and second current detection voltages V1
, V2 have a relationship of V1> V2. Therefore, the output of the first subtractor 25, that is, the first unbalance detection value Va becomes V2−V1 <0, has a negative value, and has a negative value.
5 or the second unbalance detection value Vb is V1 -V
2> 0 and has a positive value. Therefore, the first unbalance detection value Va becomes smaller than the second unbalance detection value Vb. The third subtractor 27 forms the first corrected output voltage control signal Ve1 by the operation of Ve-Va, and the fourth subtractor 28 generates the second corrected output voltage control signal Ve2 by the operation of Ve-Vb. Form. Since Va <Vb when I1> I2, Ve1> Ve2. As is clear from FIG. 6, as the voltage values of the corrected output voltage control signals Ve1 and Ve2 increase, the width of the PWM pulse decreases. Therefore,
The PWM pulse for the first converter 11 is narrowed, the PWM pulse for the second converter 12 is widened, and the output currents I1, I2 of the first and second converters 11, 12 are balanced. When the output current I1 of the first converter 11 is lower than the output current I2 of the second converter 12, the operation is reverse to that when I1> I2.

As is apparent from the above description, according to the present embodiment, the first and second unbalanced output signals Ve are corrected by the first and second unbalanced detection values Va and Vb. 2, the output currents I1 and I2 can be balanced, so that it is not necessary to make the margins of the first and second converters 11 and 12 so large, and the device can be downsized. In addition, it is not necessary to provide the components corresponding to the backflow preventing diodes 5 and 6 shown in FIG. 1, and the efficiency can be improved by the amount of power loss caused by this.

[0020]

Second Embodiment Next, a second embodiment will be described. However, the DC power supply device of the second embodiment has the same configuration as that of FIG. 2 except that the unbalance detection unit 22 of FIG. 2 is changed to the unbalance detection unit 22a of FIG. In the description of the embodiment, the unbalance detecting means 22a
Otherwise, refer to FIG. In FIG. 7, substantially the same parts as those in FIG. 2 are denoted by the same reference numerals, and description thereof will be omitted.

The imbalance detecting means 22a shown in FIG. Reference signal forming means 40
Calculates the average value of the current detection voltages V1 and V2, and comprises an adder 41 and a 1 / n dividing circuit 42. The adder 41 adds the first and second current detection voltages V1 and V2 of the lines 16a and 17a and outputs V1 + V2.
That is, the adder 41 outputs a value corresponding to the total current flowing through the load 13. N of the 1 / n dividing circuit 42 indicates the number of the converters 11 and 12, and is 2 in this embodiment. Accordingly, a reference signal Vs having a voltage value of (V1 + V2) / 2 is obtained from the 1 / n dividing circuit 42. The reference signal Vs corresponds to a target of a current value shared by the first and second converters 11 and 12. The first subtracter 25 subtracts the first current detection voltage V1 from the reference signal Vs to output a first unbalance detection value Va, and the second subtractor 26 detects the second current detection voltage Va from the reference signal Vs. The voltage V2 is subtracted to output a second unbalance detection value Vb. The first and second unbalance detection values Va and Vb are sent to the third and fourth subtracters 27 and 28 in FIG.

In FIG. 7, when V1> V2, Va <Va.
Vb, and the third and fourth subtractors 27 and 28 in FIG. 2 perform the same correction operation as in the first embodiment. Therefore, the same effect as in the first embodiment can be obtained by the second embodiment in FIG. Further, according to this embodiment, the unbalance values Va and Vb can be accurately obtained.

[0023]

Third Embodiment Next, a DC power supply according to a third embodiment will be described with reference to FIGS. However, FIGS. 8 and 9
In FIG. 7, the same reference numerals are given to substantially the same parts as those in FIGS.

The DC power supply of FIG. 8 is substantially the same as that of FIG. 2 except that a third converter 50 and a control circuit are added to the DC power supply of FIG. The third converter 50 includes first and second converters 11 and 12.
And are connected in parallel to them. The control circuit 18b is configured to control the third converter 50 in the same manner as the first and second converters 11 and 12.

The output line 51a of the current detector 51 of the third converter 50 is connected to the unbalance detector 22b in addition to the first and second current detection lines 16a and 17a. The unbalance detector 22b outputs first, second and third unbalance detection values Va, Vb and Vc indicating the imbalance between the first, second and third current detection voltages V1, V2 and V3. .

FIG. 9 schematically shows the unbalance detecting means 22b. The unbalance detecting means 22b of FIG. 9 is configured on the same principle as the unbalance detecting means 22a of FIG. 7, and includes the reference signal forming means 40a and the first, second and third subtractors 25, 26 and 52. Become. First, second and third
Of the subtractors 25, 26, 52 are connected to the first, second and third current detection lines 16a, 17a, 51a, and their positive input terminals are connected to the reference signal forming means 40a.
It is connected to the. The reference signal forming means 40a calculates the average value of V1, V2 and V3 similarly to the reference signal forming means 40 of FIG. 7, and has an adder 41a and a 1 / n dividing circuit 42a. The adder 41a includes first, second, and third
Of the current detection voltages V1, V2, and V3 of
Outputs + V3. The 1 / n dividing circuit 42a outputs Vs = (V1 + V2 + V3) / 3 where n = 3. Accordingly, the first, second, and third subtractors 25, 26, and 27 provide the first, second, and third subtractors 25, 26, and 27, respectively, which indicate imbalance based on the reference signal Vs.
And the third unbalanced detection values Va, Vb, Vc, ie, V
a = Vs-V1, Vb = Vs-V2, Vc = Vs-V
Outputs 3.

The correction output voltage control signal forming means 23 shown in FIG.
b, first, second and third correction subtractors 27, 28, 5
3 is the output voltage control signal V1 from the unbalance detection value V
a, Vb, and Vc are subtracted to output first, second, and third corrected output voltage control signals Ve1, Ve2, and Ve3. The first, second, and third control signal forming circuits 29, 30, and 54 of the control element control signal forming means 24b form a PWM signal in the same manner as in FIG. 1
Send to 2,50.

According to the third embodiment, the first and the second
The same effect as that of the embodiment can be obtained.

[0029]

[Modifications] The present invention is not limited to the above-described embodiment, and for example, the following modifications are possible. (1) Three converters 11, 12 and 5 shown in FIG.
Instead of the unbalance detection means 22b when 0 is connected in parallel, the unbalance detection means 22c in FIG. 10 can be used. In FIG. 10, the negative input terminal of the first subtractor 25 is connected to the first current detection line 16a, and the positive input terminal is connected to the second current detection line 17a. Further, the negative input terminal of the second subtractor 26 is connected to the second current detection line 17a, and the positive input terminal is connected to the third current detection line 17a.
Are connected to the current detection line 51a. Also, the third
Is connected to the third current detection line 51.
a, and this positive input terminal is connected to the first current detection line 16a. Accordingly, a first unbalance detection value Va of V2-V1 is obtained from the first subtractor 25, and a second unbalance detection value Vb of V3-V2 is obtained from the second subtractor 26. V1-
An unbalance detection value Vc of V3 is obtained. The same effect as in FIG. 8 can be obtained by the unbalance detection unit 22c in FIG. (2) The DC / DC converters 11, 12, and 50 are replaced with another known DC-D such as a half-bridge type or a full-bridge type.
It can be a C converter. (3) Instead of the DC / DC converters 11, 12, and 50, a chopper-type switching power supply, a series regulator, a switching rectifier circuit, or the like can be used. In the case of a series regulator, the control signal forming circuits 29, 30, and 54 are configured to adjust the level of a control signal (for example, a base current) of a control element (for example, a transistor) of the series regulator. Further, the output voltage can be adjusted by varying the reference voltage for error amplification. (4) The control signal forming circuits 29, 30, and 54 can be another modulation circuit such as a frequency modulation circuit other than the pulse width modulation circuit (PWM circuit). (5) The number of DC power supply circuits such as DC / DC converters may be four or more. (6) Part or all of the control circuit 18 can be formed by a digital circuit. In this case, the control circuit 18
An A / D converter is arranged at each input stage, and a D / A converter is arranged at each output stage.
Place the transducer.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a conventional DC power supply device.

FIG. 2 is a block diagram illustrating a DC power supply device according to a first embodiment of the present invention.

FIG. 3 is a circuit diagram showing a converter and a control signal forming circuit of FIG. 2 in detail.

FIG. 4 is a circuit diagram showing first and second subtracters of FIG. 2;

FIG. 5 is a circuit diagram showing third and fourth subtractors of FIG. 2;

FIG. 6 is a waveform chart showing a state of each part of the control signal forming circuit of FIG. 3;

FIG. 7 is a circuit diagram illustrating an unbalance detection unit according to a second embodiment.

FIG. 8 is a block diagram illustrating a DC power supply device according to a third embodiment.

FIG. 9 is a circuit diagram showing the unbalance detecting means of FIG.

FIG. 10 is a circuit diagram showing a modification of the unbalance detection means.

[Explanation of symbols]

 11, 12, 50 DC / DC converter 13 Load 16, 17, 51 Current detector 21 Error amplifier 22, 22a, 22b Unbalance detecting means 23, 23b Corrected output voltage control signal forming means 24, 24b Control element control signal forming means

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Yukihiro Kanaga 3-6-3 Kitano, Niiza-shi, Saitama F-term in Sanken Electric Co., Ltd. 5G065 AA00 AA01 DA01 DA07 EA01 HA04 HA07 JA01 LA01 LA02 MA09 MA10 NA06 5H410 CC02 DD02 DD09 DD10 EA11 EA38 EB09 EB37 FF03 FF05 FF25 FF26 5H730 AA14 BB43 BB57 BB82 DD04 EE02 EE07 FD01 FD31 FF02 FG05

Claims (4)

[Claims] A plurality of DC power supply circuits each having a control element for output voltage control and connected in parallel with each other so as to supply power to a common load; A plurality of current detection means for detecting each; an output voltage detection means for detecting a voltage between terminals of the load; a reference voltage means; an output voltage detection value obtained from the output voltage detection means; Output voltage control signal forming means for forming a voltage control signal corresponding to the difference between the reference voltage value provided by the voltage means, and output currents of the plurality of DC power supply circuits based on outputs of the plurality of current detecting means. An unbalance detection unit that outputs a plurality of unbalance detection values indicating unbalance; and the power supply so that the unbalance of output currents of the plurality of DC power supply circuits can be eliminated. Correction output voltage control signal forming means for correcting a pressure control signal, the correction output voltage control signal forming means forming a plurality of corrected output voltage control signals comprising a value corresponding to a difference between the plurality of unbalanced detection values and the voltage control signal. A control element control signal forming means for forming a control signal for controlling a control element of the plurality of DC power supply circuits based on the plurality of corrected output voltage control signals. 2. The plurality of DC power supply circuits are first and second DC power supply circuits, and the plurality of current detection units output first and second current detection values. A first subtraction unit that subtracts the first current detection value from the second current detection value and outputs a first unbalance detection value, Second subtraction means for subtracting the second current detection value from the first current detection value to output a second unbalance detection value, wherein the correction output voltage control signal forming means comprises: Third subtraction means for subtracting the first unbalance detection value from the voltage control signal to form a first corrected output voltage control signal, and subtracting the second unbalance detection value from the output voltage control signal To form a second corrected output voltage control signal And a control element control signal forming means, wherein the output voltage of the first DC power supply circuit changes in inverse proportion to the value of the first corrected output voltage control signal. First control element control signal forming means for forming a first control element control signal for controlling the control element of the first DC power supply circuit; and a second correction output voltage control signal. A second control element control signal for forming a second control element control signal for controlling the control element of the second DC power supply circuit so that the output voltage of the second DC power supply circuit changes in inverse proportion 2. The DC power supply according to claim 1, further comprising a forming unit. 3. The reference signal forming means for obtaining an average value of a plurality of current detection values obtained from the plurality of current detectors and outputting the average value as a reference signal, 2. The DC power supply device according to claim 1, further comprising a plurality of subtraction means for calculating a difference between the current detection value and the reference signal and outputting a plurality of unbalance detection values. 4. The DC power supply device according to claim 1, wherein a backflow prevention diode is not connected between the plurality of DC power supply circuits and the load.