JP2719745B2 - Parallel operation of DC power supply - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a parallel operation device for a plurality of constant voltage DC power supplies for supplying power to a load.

[0002]

2. Description of the Related Art As a parallel operation device of a constant voltage DC power supply device, there is a device in which the output sides of a plurality of constant voltage DC power supply devices are connected in parallel to each other to supply power to one load.

[0003]

In such a parallel operation device, when the parallel operation is simply performed, each DC power supply device is determined by the internal impedance of each DC power supply device and the value of the DC constant voltage generated by each DC power supply device. Irrespective of the output capacity of the DC power supply, the burden current of each DC power supply is determined. Therefore,
There has been a problem in that a load current greater than the output capacity of each DC power supply flows and the DC power supply may be destroyed.

[0004] When the load current is small, a specific DC power supply may bear the entire load current, and other DC power supplies may not share the load current. In this case, the specific DC power supply is not destroyed because the total load current borne by it is smaller than its output capacity,
Since one unit shares the entire load current, there is a problem that the life of this specific DC power supply device is shortened.

[0005] It is an object of the present invention to operate a plurality of DC power supply units in parallel so as to share a load current with good balance.

[0006]

In order to achieve the above object, according to the present invention, a plurality of DC power supply units are connected in parallel, and these DC power supply units control a power control element to control a DC power supply. DC generation means for generating an output voltage; voltage detection means for detecting the DC output voltage; and controlling the power control element based on a difference between a detection output signal of the voltage detection means and a reference signal to control the DC output. Control means for setting the voltage to a constant voltage. Current detecting means is provided for each DC power supply so as to detect the output current of each DC power supply. Further, an error amplifier for changing the reference signal is provided for each DC power supply. These error amplifiers have first and second input terminals, respectively. Two sets of shunt means are provided to shunt the output signal of each current detecting means to the corresponding first and second input terminals of the error amplifying means, and the first input terminal side of each of the error amplifying means is provided. Are formed between the flow dividing means.

Also, load current detecting means for detecting a current flowing through a load, and an output signal of the load current detecting means and an output signal of each of the error amplifying means are added to correspond to each other. A plurality of correction means for correcting the reference signal.

[0008]

According to the present invention, in each DC power supply device, the control means controls the power control element based on the deviation between the output signal of the voltage detection means representing the DC output voltage and the reference signal. The output voltage is made constant. Further, the current detection means generates an output representing the output current of each DC power supply. The output signals of these current detecting means are supplied to the first and second input terminals of the corresponding error amplifying means via two shunt means.

[0009] Here, suppose that two DC power supplies are operated in parallel, and the burden current of one DC power supply is one more.
If the load current is larger than the load current of one of the DC power supplies, the other DC power supply via the shunt from the shunt means on the first input terminal side of the error amplifying means corresponding to the DC power supply with the higher load current An output signal is supplied from a current detecting means provided in a DC power supply having a large burden current to a shunting means on a first input terminal side of an error amplifying means corresponding to the device.

As a result, the difference between the signals supplied to the first input terminal and the second input terminal of the error amplifying means on the other DC power supply device side increases, and the output of the error amplifying means increases. . As a result, the reference signal on the other DC power supply increases, and the current burden on the other DC power supply increases. Further, the difference between the signals supplied to the first input terminal and the second input terminal of the error amplifying means on the side of the DC power supply device having a large burden current becomes small. As a result, the burden current of the DC power supply device having the large burden current decreases.

When the output signal of the load current detecting means representing the load current and the output signal of each of the error amplifying means are added by the correcting means and the reference signal is corrected based thereon, the fluctuation of the load voltage can be obtained. Can also be accommodated.

[0012]

1 and 2 show a first embodiment. In this embodiment, as shown in FIG. 2, two DC power supplies 1, 2
1 can be operated in parallel to supply power to the load 9. The DC power supply 1 has an input rectifier 2 for rectifying a commercial AC power supply 10, and the output of the input rectifier 2 is smoothed by a smoothing capacitor 3. As a result, the commercial AC power supply 10 is converted to DC.

The direct current is supplied to the primary side of the high-frequency transformer 5 and
It is supplied to a power control element, for example an IGBT or a series circuit with a transistor. A high-frequency signal is induced on the secondary side of the high-frequency transformer 5 by high-speed on / off control of the power control element. That is, a DC power supply is converted to a high-frequency power supply.

The high frequency power is rectified by an output rectifier 6 and supplied to a load 9 via a smoothing reactor 7 and a backflow preventing diode 8. The voltage on the output side of the smoothing reactor 7 and the output side rectifier 6 is a voltage detector 11
And supplied to one input of the error amplifier 12, and the other input of the error amplifier 12
6 supplies a reference signal, and the error amplifier 12
An error between the detection signal of the voltage detector 11 and the reference signal is amplified and supplied to the switching driving device 13. This switching drive device 13 controls on / off of the power control element 4 to make the voltage on the output side of the smoothing reactor 7 a constant value. That is, a constant voltage is applied.

In the DC power supply 21, a constant voltage is similarly set. Note that each component of the DC power supply 21 is assigned a reference number obtained by adding 20 to the value of the reference number assigned to each component of the DC power supply 1, and a description thereof will be omitted.

The rectifier 6 on the output side of the DC power supplies 1 and 21
The current flowing from 26 to the load 9 is a Hall CT (current transformer)
Etc., respectively detected by the current detectors 15, 35,
It is supplied to the parallel operation control device 51. In addition, load 9
Is detected by a load current detector 52 also composed of a Hall CT or the like and supplied to the parallel operation control device 51.

The parallel operation control device 51 has an error amplifier 60 constituted by an operational amplifier as shown in FIG. 1, and an inverting input terminal and a non-inverting input terminal of the error amplifier 60 have input terminals of the same size. An output signal from the current detector 15 having an impedance is supplied to an inverting input terminal of the error amplifier 60 via a shunting unit, for example, a resistor 53, and further connected to a series circuit of the shunting unit, for example, resistors 54 and 56. The signal is supplied to the non-inverting input terminal of the error amplifier 60 via the input terminal. The series resistance value of the resistors 54 and 56 and the resistor 53
Are selected to be equal.

The parallel operation controller 51 includes an error amplifier 6
An error amplifier 61 similar to 0 is also provided, and its inverting input terminal is supplied with the output signal of the current detector 35 via the resistor 57, and its non-inverting input terminal is connected to the resistors 58, 5
The output signal of the current detector 35 is supplied via the serial circuit 9. The combined resistance value of the resistors 58 and 59 is selected to be equal to the resistance value of the resistor 57. And, between the interconnection point of the resistors 54 and 56 and the interconnection point of the resistors 58 and 59, the electronic switches 62,
63 forms a shunt.

The parallel operation device 51 further includes an amplifier 6
The output signal of the load current detector 52 is supplied to the amplifier 64 via the resistor 101.
Further, an auxiliary signal from an auxiliary signal source 65 is supplied via a resistor 102, and the amplifier 64 amplifies a signal obtained by adding the detection signal of the load current detector 52 and the auxiliary signal.

The output signal of the error amplifier 60 and the output signal of the amplifier 64 are passed through resistors 66 and 67 to the insulated amplifier 7.
0, where it is added and amplified, and then the reference signal source 1
6 and is supplied to the error amplifier 12. Similarly, the output signal of the error amplifier 61 is
The signal is supplied to the insulating amplifier 71 via the reference numerals 8 and 69, is added and amplified here, is superimposed on the reference signal from the reference signal source 36, and is supplied to the error amplifier 32.

For example, when the DC power supply 1 is operated alone, a high-frequency voltage is induced on the secondary side of the high-frequency transformer 5 by the on / off control of the power control element 4 as described above, and this is the output-side rectifier 6. Rectified, smoothed by the smoothing reactor 7 and backflow blocking diode 8
To the load 9. At this time, reactor 7
Is detected by a voltage detector 11, and an error between the detection signal and a reference signal from a reference signal source 16 is amplified by an error amplifier 12 and supplied to a switching drive device 13. Controls the power control element 4. As a result, the high-frequency voltage induced on the secondary side of the high-frequency transformer 5 changes, and the DC voltage supplied to the load 9 is made constant.

At this time, the signal representing the load current from the current detector 15 is shunted to the error amplifier 60 of the parallel operation control device 51 via the series circuit of the resistors 54 and 56 and the resistor 53. Since the combined resistance value of the resistors 54 and 56 is equal to the resistance value of the resistor 53, the signals supplied to the inverting input terminal and the non-inverting input terminal of the error amplifier 60 are equal, and the error amplifier 60 does not generate an output. . Since the electronic switches 62 and 63 are open, the current detector 1
5 does not flow to the error amplifier 61 side.

When the DC power supply 21 is operated alone, the operation is the same as when the DC power supply 1 is operated alone.

When the DC power supplies 1 and 21 are operated in parallel, the electronic switches 62 and 63 in the parallel operation controller 51 are used.
And the interconnection point of resistors 54 and 56 and resistor 5
A shunt is formed between the interconnection points 8 and 59. For convenience of explanation, the operation of the parallel operation in a state where the load current detector 52 and the amplifier 64 are not provided will be described.

When the DC power supplies 1 and 21 are operated in parallel, the current detector 15 generates a signal representing the current flowing from the DC power supply 1 to the load 9, and the current detector 35 outputs the signal from the DC power supply 21 to the load 9. To generate a signal representing the current flowing through the device. Here, assuming that the current flowing from the DC power supply 1 to the load 9 is larger than the current flowing from the DC power supply 21 to the load 9, the output signal of the current detector 15 is larger than the output signal of the current detector 35, This is supplied to the inverting input terminal of the error amplifier 60 via the resistor 53,
The voltage is supplied to the non-inverting input terminal of the error amplifier 60 via the resistors 54 and 56, and is also supplied from the resistor 54 to the non-inverting input terminal of the error amplifier 61 via the electronic switches 62 and 63 and the resistor 59. Is done.

Therefore, the voltage generated at the inverting input terminal of the error amplifier 60 becomes higher than the voltage generated at the non-inverting input terminal of the error amplifier 60, and the output signal of the error amplifier 60 becomes a negative value. This is amplified by the insulating amplifier 70 and added to the reference signal generated by the reference signal source 16, and the reference signal supplied to the error amplifier 12 has a small value, so that the output voltage of the DC power supply 1 is small. Value.

The detection signal of the current detector 35 is supplied to an inverting input terminal of an error amplifier 61 via a resistor 57, and a resistor 58,
59. The output signal of the current detector 15 is also supplied to the non-inverting input terminal of the error amplifier 61 via the resistor 54 and the electronic switches 62 and 63. As a result, the voltage of the non-inverting input terminal of the error amplifier 61 becomes higher than the voltage of the inverting input terminal, and the output voltage of the error amplifier 61 becomes a positive value. This is amplified by the insulating amplifier 71 and added to the reference signal of the reference signal source 36. Therefore,
The reference signal supplied to the error amplifier 32 becomes larger than the previous value, and as a result, the output voltage of the DC power supply 21 increases.

As described above, when the voltage generated by the DC power supply 1 decreases and the voltage generated by the DC power supply 21 increases, the output signals of the current detectors 15 and 35 become equal and the electronic switch 62 , 63 via the current detector 1
5 is continued until the output signal of No. 5 is no longer supplied to the non-inverting input terminal of the error amplifier 61, that is, until the currents borne by both power supply devices 1 and 21 become equal.

When the output signal of the current detector 35 is larger than the detection signal of the current detector 15, the output signal of the current detector is inverted via the electronic switches 63 and 61 to the non-inverted state of the error amplifier 60. The output signal of the error amplifier 61 becomes negative, the output signal of the error amplifier 60 becomes positive, the output voltage of the DC power supply 1 increases, and the output voltage of the DC power supply 21 decreases. This operation is continued until the currents borne by the DC power supplies 1 and 21 become equal.

By the way, the voltage applied to the load 9 decreases due to the voltage drop due to the backflow preventing diodes 8 and 28 of the DC power supplies 1 and 21 and the wiring impedance between the DC power supplies 1 and 21 and the load 9. There is. In order to prevent this, the current flowing through the load 9 is detected by the load current detector 52, and the output signal is amplified by the amplifier 64 and then supplied to the isolation amplifiers 70 and 71. Therefore, the isolation amplifiers 70 and 71 supply the signals obtained by adding the output signals of the amplifiers 64 to the output signals of the error amplifiers 60 and 61 to the error amplifiers 12 and 16. As a result, a desired voltage is applied to the load 9 and the currents borne by the DC power supplies 1 and 21 become equal. The auxiliary signal source 65 is provided for adjusting a signal supplied to the isolation amplifiers 70 and 71.

FIG. 3 shows a parallel operation control device 5 according to the second embodiment.
1A is shown. In this embodiment, three DC power supply units are operated in parallel, and the same parts as those in the first embodiment are denoted by the same reference numerals and their description is omitted. An output signal of a current detector 95 provided in a third DC power supply is supplied to an inverting input terminal of a third error amplifier 76 via a resistor 72, and a series circuit of resistors 73 and 74 is provided. , Is also supplied to the non-inverting input terminal of the error amplifier 76. An electronic switch 75 is connected between the interconnection point of the resistors 73 and 74 and the electronic switch 63. The output signal of the error amplifier 76 is supplied to an insulating amplifier 79 via a resistor 78. The output signal of the amplifier 64 is also supplied to the insulation amplifier 79 via the resistor 77, and the output signal of the insulation amplifier 79 is supplied to the error amplifier 92 of the third DC power supply device. Of course, this error amplifier 92 is for controlling the power control element of the third DC power supply, and a reference signal is also supplied from the reference signal source 96.

In this embodiment, as in the first embodiment,
The operation is performed so that the currents borne by the power supply devices are equal and the output voltage has a desired value.

In the above embodiment, the number of DC power supplies to be operated in parallel is two or three, but more DC power supplies can be operated in parallel. Further, the configuration of the DC power supply device is not limited to the configuration described in the above embodiment. For example, the configuration may be such that the AC power supply is rectified by a rectifier using a thyristor and the firing angle of the thyristor is controlled. Can also. In the above embodiment,
Although the electronic switches 62, 63, and 75 were used in consideration of the case where the DC power supply unit is independently operated, the electronic switch is not provided when the parallel operation is always performed. And the interconnection point of the resistors 54 and 56 and the resistor 5
8 and 59 are connected to each other. In the case of the second embodiment, the interconnection points of the resistors 54 and 56 and the resistors 58 and 59 are connected.
And the interconnection points of the resistors 73 and 74 may be directly connected.

[0034]

As described above, according to the present invention, the output current of each DC power supply is detected by a plurality of current detecting means, and the output current of each of the plurality of error amplifying means provided for each DC power supply is detected. The output signals of the current detection means corresponding to the first and second input terminals are shunted by the shunt means, and the shunt path through which the output signal of the current detection means flows between the shunt means on the first input terminal side of each error amplification means. Since it is formed, the load current of each DC power supply can be equalized, no DC power supply is destroyed, and the life of a specific DC power supply is not shortened. Furthermore, since the current flowing through the load is detected by the load current detecting means, and the output signal of each error amplifying means is added by the correcting means to correct the reference signal of the corresponding DC power supply, so that the current is applied to the load. The voltage can be kept constant.

[Brief description of the drawings]

FIG. 1 is a block diagram of a parallel operation control device of a first embodiment of a parallel operation device of a DC power supply device according to the present invention.

FIG. 2 is a block diagram of the first embodiment.

FIG. 3 is a block diagram of a parallel operation control device according to the second embodiment.

[Explanation of symbols]

1 21 DC power supply device 4 24 Power control element 11 31 Voltage detector 12 32 Error amplifier (control means) 13 33 Switching drive device (control means) 15 35 Current detector 52 Load current detector 53 54 56 57 58 59 Resistor (Diversion means) 60 61 Error amplifier 62 63 Electronic switch (shunt) 70 71 Insulation amplifier (correction means)

Claims (1)

(57) [Claims] 1. A DC generation means for controlling a power control element to generate a DC output voltage, a voltage detection means for detecting the DC output voltage, and a difference between a detection output signal of the voltage detection means and a reference signal. A DC power supply having a control means for controlling the power control element based on the DC output voltage based on the DC power supply based on a plurality of DC power supply units that operate in parallel and supply power to a load. A plurality of current detecting means provided in each of the DC power supplies so as to detect an output current of each of the DC power supplies; first and second input terminals provided in each of the DC power supplies; A plurality of error amplifying means for changing the reference signal of the corresponding DC power supply, and a first and a second input of the corresponding error amplifying means for outputting the output signals of the respective current detecting means. A set of two shunting means for shunting to the terminal, a shunt formed between the shunting means on the first input terminal side of each of the error amplifying means, and a load current detecting means for detecting a current flowing through the load And a plurality of correcting means for adding the output signal of the load current detecting means and the output signal of each of the error amplifying means to correct the reference signal of the corresponding DC power supply device. Parallel operation of equipment.