JPH08115133A - Power unit - Google Patents

Abstract

PURPOSE: To reduce the number of parts and to miniaturize the power unit by providing at least one operational amplifier having a negative power supply electrode connected to the load side of a current detecting resistor and detecting voltages at both terminals of the current detecting resistor while using the operational amplifier. CONSTITUTION: A positive power supply terminal 57 and a negative power supply terminal 53 of an operational amplifier 7 are connected parallelly with a load 9, the same voltage as applied to the load 9 is impressed to the operational amplifier 7, and power is supplied to the operational amplifier 7. Since an opposite phase input terminal 56 is connected through an input resistor 5 to the connecting point of a main circuit 10 and a current detecting resistor 3, a detecting voltage is impressed to the opposite phase input terminal 56. The impressed detecting voltage is amplified based on the ratio of an input resistor 5 to a feedback resistor 4 and the result is outputted from an output terminal 54. The outputted voltage is made a prescribed multiple of the detecting voltage and this is a voltage proportional to the instantaneous value of a load current. This voltage is transmitted to the main circuit 10 by a signal transmitting means 8 and used for controlling the load current. Thus, a voltage source for operating the operational amplifier 7 is not used at all.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power supply device such as an AC-DC converter or a DC-DC converter which supplies stable DC power to a load.

[0002]

2. Description of the Related Art Conventionally, an AC-DC converter or D
As a current detection circuit used in a power supply device such as a C-DC converter, a current detection circuit having a configuration as described in Japanese Utility Model Publication No. 2-72638 has been widely used. FIG. 2 shows a current detection circuit configured as described in the above publication. In FIG. 2, 101 is a DC input power source, and 1
10-1 to 110-n are DC-DC converters in which n units are connected in parallel to the DC input power supply 101, 102 is a main circuit, 103 is a control circuit, 104 and 105 are operational amplifiers, 106 is a current detection resistor, 107 and 108 are operating power supplies for the operational amplifiers 104 and 105, and 109 is a load. In this method, the power input from the DC input power supply 101 is converted into a desired voltage value by the main circuit 102 and supplied to the load 109. At this time, the output current is passed through the current detection resistor 106, and the voltage drop generated across the resistor is detected by the operational amplifier 1.
Amplify with 05 and detect. In order to operate the operational amplifiers 105 and 106, generally two positive and negative DC power supplies are required. In FIG. 2, the operating power supplies 107 and 108 correspond to this, and in the actual circuit, these operating power supplies 10 are used.
7, 108 are generally made from the DC input power supply 101 in the DC-DC converter 102-1.

[0003]

In a power supply device such as an AC-DC converter or a DC-DC converter, there is a strong demand for cost reduction, component saving, and size reduction of the device.
However, in the conventional method, two DC power supplies of a positive voltage and a negative voltage are required to operate the operational amplifier used in the current detection circuit, and these power supplies are separate from the power supplied to the load. It is produced inside the device. Therefore, in such a system, the components of the two DC power supplies of the positive voltage and the negative voltage hinder the reduction of the components, the size reduction, and the cost reduction of the entire power supply device.

In view of the above-mentioned circumstances, an object of the present invention is to use a plurality of independent DC power supplies for operating the operational amplifier, and to reduce the number of parts and the size without complicate the circuit configuration. Another object of the present invention is to provide a power supply device suitable for cost reduction.

[0005]

The above object is to provide a power supply device having a main circuit for supplying DC power to a load, between the low voltage side of the load and the low voltage side of the output of the main circuit. It has a connected current detection resistor and at least one operational amplifier having a negative power supply electrode connected to the load side of the current detection resistor, and detects the voltage across the current detection resistor using the operational amplifier. It is achieved by

[0006]

According to the present invention, the current output from the main circuit of the power supply device flows through the load, flows through the current detection resistor and returns to the main circuit, and a voltage drop proportional to the load current flows across the current detection resistor. appear. At this time, an operational amplifier in which the negative power supply electrode is connected to the load side of the current detection resistor connected between the low voltage side of the load and the low voltage side of the output of the main circuit of the power supply is used, and Of both ends of the resistor, the high potential side connected to the load is connected to the positive phase input terminal of the operational amplifier, and the low potential side connected to the main circuit is connected to the negative phase input terminal. Here, the product of the resistance value of the current detection resistor and the rated value of the output current of the power supply device is used by using an operational amplifier in which the minimum value of the common mode input voltage of the operational amplifier is lower than 0 V, for example, about −0.3 V. Is 0.3 V or less, the operational amplifier operates normally, and a positive voltage proportional to the voltage across the current detection resistor is output to the output terminal of the operational amplifier with reference to the low potential side of the load. . As a result, a voltage lower than the voltage of the negative power supply terminal of the operational amplifier can be detected using the operational amplifier. As described above, according to the present invention, the load current can be quickly and accurately measured without using a plurality of independent DC power supplies for operating the operational amplifiers as a power supply device and without using a complicated circuit configuration. Therefore, it is possible to reduce the number of parts, reduce the size, and reduce the cost.

[0007]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a circuit configuration diagram of a power supply device showing a first embodiment of the present invention, and shows a configuration of an AC-DC converter. In FIG. 1, 1 is an external AC power supply, 2 is AC-DC
Converter, 3 is current detection resistor, 4 is feedback resistor, 5 and 6
Is an input resistance, 7 is an operational amplifier, 8 is a signal transmission means, 9 is a load, 10 is a main circuit, 51 is a ground terminal, 52 is a DC output terminal, 53 is a negative power supply terminal, 54 is an output terminal, and 55 is a positive phase. An input terminal, 56 is a negative phase input terminal, and 57 is a positive power supply terminal. The external AC power supply 1 is connected to the main circuit 10 inside the AC-DC converter 2, and the main circuit 10 inside the AC-DC converter 2 is connected to the DC output terminal 52 and one of the current detection resistors 3 to detect the current detection resistor. The other side of 3 is the ground terminal 5
1, the DC output terminal 52 and the ground terminal 51 are connected to the external load 9. As the operational amplifier 7 used in this embodiment, a single power supply operation is possible, and the lowest value of the common mode input voltage is a negative voltage (for example, a voltage of about −0.3 V), that is, a negative voltage input is applied. Use possible types of operational amplifiers. This operational amplifier 7 has a negative power supply terminal 5
3, output terminal 54, positive phase input terminal 55, negative phase input terminal 5
6 and a positive power supply terminal 57, of which the positive power supply terminal 57 is the DC output terminal 52 and the negative power supply terminal 53.
Is connected to the ground terminal 51, and the positive-phase input terminal 55 is connected to the ground terminal 51 via the input resistor 6. On the other hand, the negative phase input terminal 56 is connected to the connection point between the main circuit 10 and the current detection resistor 3 via the input resistor 5. The output terminal 54 is
It is connected to the negative phase input terminal 56 via the feedback resistor 4 and also to the signal transmission means 8. Further, the signal transmission means 8 is connected to the ground terminal 51. Signal transmission means 8
Can be realized by using an element such as a photocoupler or an optical isolator.

The operation of this embodiment will be described below. First, the AC voltage input from the external AC power supply 1 is AC-
It is input to the main circuit 10 inside the DC converter 2 and is converted into stable DC in the main circuit 10. The DC current generated in the main circuit 10 is supplied to the load 9 from the DC output terminal 52, flows from the ground terminal 51 through the current detection resistor 3 and returns to the main circuit 10 in a closed loop. At this time, the current flowing through the load 9 flows through the current detection resistor 3 as it is, and a voltage drop that is determined by the product of the load current and the resistance value of the current detection resistor 3 occurs across the current detection resistor 3. One of the current detection resistors 3 is connected to the ground terminal 51 and its potential is 0.
Therefore, the other potential of the current detection resistor 3 becomes a negative voltage. This voltage is called a detection voltage. The positive power supply terminal 57 and the negative power supply terminal 53 of the operational amplifier 7 are connected in parallel with the load 9, and the same voltage as that of the load 9 is applied to the operational amplifier 7 to supply power to the operational amplifier 7. The positive phase input terminal 55 of the operational amplifier 7 is connected to the ground terminal 51 via the input resistor 6, and the voltage of the positive phase input terminal 55 is 0.
Is. On the other hand, since the negative-phase input terminal 56 is connected to the connection point between the main circuit 10 and the current detection resistor 3 via the input resistor 5, the above-mentioned detection voltage is applied to the negative-phase input terminal 56. Considering the loss generated in the current detection resistor 3, the absolute value of the detection voltage is preferably as small as possible, and the absolute value of the detection voltage when the load current becomes maximum is set to approximately 0.1 V or less. Is preferred. The value of the current detection resistor 3 is preferably about 1 mΩ to 2 mΩ when the maximum value of the load current is 50 A, for example. If the minimum value of the common mode input voltage of the operational amplifier is lower than 0V, for example, about -0.3V, and the product of the resistance value of the current detection resistor and the rated value of the output current of the power supply device is 0.3V or less. The operational amplifier normally operates, and a positive voltage proportional to the voltage across the current detection resistor is output to the output terminal of the operational amplifier with reference to the low potential side of the load. The detection voltage applied to the negative-phase input terminal 56 of the operational amplifier 7 is amplified by the ratio of the input resistance 5 and the feedback resistance 4 (this is G), and is output from the output terminal 54. At this time, in order to avoid saturation of the voltage of the output terminal 54, it is necessary to satisfy the following conditions. That is, the ratio G between the input resistance 5 and the feedback resistance 4 needs to be set sufficiently smaller than the ratio between the maximum absolute value of the detection voltage and the DC output voltage of the AC-DC converter 2.
For example, the maximum absolute value of the detected voltage is 100 mV, AC
-When the DC output voltage of the DC converter 2 is 5V,
Since these ratios are 50 times, it is desirable to select G to be 10 times to 20 times, which is sufficiently smaller than 50 times. If the input resistance 5 is 1 kΩ, the feedback resistance 4 is 10 kΩ to 20 kΩ.
kΩ is preferred. The voltage output from the output terminal 54 is
It is G times the detection voltage, which is a voltage proportional to the instantaneous value of the load current. This voltage is transmitted to the main circuit 10 by the signal transmission means 8 and used for controlling the load current. As a control method, for example, a voltage control for maintaining a constant DC output voltage is mainly performed, and when the current exceeds a desired value, so-called voltage droop control in which the voltage droops in order to protect the power supply can be realized. It is possible. According to the present embodiment, it is possible to detect the load current quickly and accurately by using a single power supply type operational amplifier and using a simple circuit system without using any voltage source for operating the operational amplifier. Therefore, it is possible to promote the reduction of parts of the device, the cost reduction, the size reduction, and the like. Although the present embodiment describes an AC-DC converter that converts alternating current to direct current, this is similarly applied to other applications such as a DC-DC converter that converts direct current to direct current having a different voltage. It goes without saying that it can be realized.

Next, FIG. 3 is a circuit configuration diagram of a power supply device showing a second embodiment of the present invention.
The structure which connected the converter in parallel is shown. In FIG.
2-1 and 2-n are AC-DC converters, 11 is an operational amplifier, 12 is a signal line, 13 is a diode, and 14 is a resistor. In addition, the same components as those shown in FIG. 1 are designated by the same reference numerals. In FIG. 3, AC-
The DC converters 2-1 to 2-n have exactly the same circuit configuration and are connected in parallel to the external AC power supply 1. The internal circuit of the AC-DC converter 2-1 will be described below. The main circuit 10 of the AC-DC converter 2-1 is connected to the DC output terminal 52 and the current detection resistor 3 via the diode 13. The DC output terminal 52 and the ground terminal 51 are connected to the same terminal of another AC-DC converter, and further connected to the load 9. As the operational amplifiers 7 and 11 used in this embodiment, as in the case of the first embodiment, the operational amplifiers of the type capable of operating with a single power supply and capable of inputting a negative voltage are used. The positive power supply terminal 57 of the operational amplifier 7 is connected to the anode of the diode 13. Also, the output terminal 5 of the operational amplifier 7
Reference numeral 4 is connected to the positive phase input terminal of the operational amplifier 11 and at the same time connected to one end of the resistor 14. The other end of the resistor 14 is connected to the negative phase input terminal of the operational amplifier 11. A signal line 12 is connected to this connection point, and this signal line 12 is connected to all the same connection points of the AC-DC converters 2-1 to 2-n. The positive power supply terminal of the operational amplifier 11 is connected to the anode of the diode 13, and the negative power supply terminal is connected to the ground terminal 51. Operational amplifier 1
The output terminal of 1 is connected to the signal transmission means 8. Further, the signal transmission means 8 is connected to the ground terminal 51. The other structure is similar to that of the first embodiment shown in FIG.

The operation of this embodiment will be described with reference to FIG. This embodiment differs from the first embodiment in that the AC
-The DC converter has a parallel configuration of n units like 2-1 to 2-n, the diode 13 is connected to the output terminal of the AC-DC converter, and another calculation is performed at the output terminal 54 of the operational amplifier 7. That is, the amplifier 11 and the resistor 14 are connected and the signal line 12 is connected between the other AC-DC converter. Therefore, this point will be described in detail. Regarding the operation of other circuits,
This is similar to the first embodiment shown in FIG. First, the direct current generated in the main circuit 10 passes through the diode 13 and is supplied from the direct current output terminal 52 to the load 9 and the ground terminal 51.
Through the current detection resistor 3 to return to the main circuit 10 in a closed loop. This operation is the same for other AC-DC converters, and the total value of the output currents of the AC-DC converters 2-1 to 2-n flows through the load 9. The output current of each AC-DC converter is output to the output terminal 54 of the operational amplifier 7 as a voltage proportional to the instantaneous value of the output current, as described in the first embodiment. This voltage is input to the positive phase input terminal of the operational amplifier 11. On the other hand, a resistor 1 is connected to the output terminal 54 of each AC-DC converter.
Since 4 are connected and connected by the signal line 12, the voltage appearing on the signal line 12 is an average voltage of the voltages output to the output terminal 54 of each AC-DC converter. This average voltage corresponds to the average value of the output current of each AC-DC converter. This average voltage is input to the negative phase input terminal of the operational amplifier 11, and the output terminal 5 is connected to one positive phase input terminal.
The voltage of 4 is input. In the operational amplifier 11, these 2
Compare two voltages. This is nothing but the comparison between the average value and the instantaneous value of the output current of each AC-DC converter. That is, the output voltage of the operational amplifier 11 is a voltage obtained by amplifying the error between the average value of the output current of each AC-DC converter and the instantaneous value of the output current of its own AC-DC converter. In this embodiment, this error amplified voltage is input to the signal transmission means 8 and is transmitted to the main circuit 10 as a current error signal, and control is performed so that this error becomes zero.
Hereinafter, this control method is referred to as an average current tracking control method. This average current tracking control method is, for example, so-called PWM control that changes the ratio between the ON period and the OFF period of the switching element used in the main circuit 10 according to the error between the instantaneous value of the output voltage and the voltage command value. AC-DC
This is to control the output current by slightly changing the output voltage by adding or subtracting the current error component to or from the voltage command value when controlling the output voltage of the converter to be constant. According to the present embodiment, a single power supply type operational amplifier is used, and no voltage source for operating the operational amplifier is used at all. It is possible to detect output current quickly and accurately.
By calculating the average value of the output current of the C-DC converter and feeding back those errors to the control circuit, all AC
-The average current follow-up control for uniformly controlling the output current of the DC converter becomes possible. Further, since it is not necessary to prepare a special positive and negative voltage source as the operating voltage source of the operational amplifier, it is possible to promote the reduction of the parts of the device, the cost reduction, the size reduction and the like. In addition, although an AC-DC converter that converts alternating current into direct current is also described in this embodiment, this is a DC-converter that converts direct current into direct current having different voltages.
It can be similarly realized for other configurations such as a DC converter.

Next, FIG. 4 is a circuit configuration diagram of a power supply device showing a third embodiment of the present invention, and shows a configuration in which a plurality of AC-DC converters are connected in parallel as in FIG. In FIG. 4, 15 is a diode, 16 is an input resistance, and 17
Is an operational amplifier. In addition, the same components as those shown in FIGS. 1 and 3 are designated by the same reference numerals. In FIG. 4, AC-DC converters 2-1 to 2
The n units of -n have exactly the same circuit configuration and are connected in parallel to the external AC power supply 1. This embodiment differs from the embodiment shown in FIG. 3 in that the output terminal of the operational amplifier 7 is connected to the positive phase input terminal of the operational amplifier 17, and the anode of the diode 15 is connected to the output terminal of the operational amplifier 17. The cathode of the diode 15 is connected to the negative phase input terminal of the operational amplifier 17, the cathode of the diode 15 is connected to one end of the input resistor 16, and the other end of the input resistor 16 is connected to the operational amplifier 11.
Of the diode 15 is connected to the signal line 12, and the other structure is the same as that of the second embodiment shown in FIG. Also,
As the operational amplifiers 7, 11 and 17 used in this embodiment, as in the first and second embodiments, the operational amplifiers of the type capable of operating a single power source and receiving a negative voltage. To use.

Therefore, the operation of the difference from the embodiment shown in FIG. 3 will be described in detail below. The operation of the other circuits is similar to that of the second embodiment shown in FIG. First, a voltage proportional to the output current of each AC-DC converter is output to the output terminal of the operational amplifier 7. This output voltage is input to the positive phase input terminal of the operational amplifier 17, while the voltage of the signal line 12 is input to the negative phase input terminal of the operational amplifier 17. The operational amplifier 17 has a so-called voltage follower configuration via the diode 15, and when the instantaneous value of the voltage of the positive phase input terminal of the operational amplifier 17 is higher than the voltage of the signal line 12, the signal line 1
The voltage of 2 rises to the same value as the instantaneous value of the voltage of the positive phase input terminal. However, when the instantaneous value of the voltage of the positive phase input terminal of the operational amplifier 17 is lower than the voltage of the signal line 12, the voltage of the signal line 12 does not change. As a result, the voltage of the signal line 12 is always the highest voltage among the output voltages of the operational amplifier 7 of each AC-DC converter. That is, signal line 1
2 indicates the maximum value of the output current of each AC-DC converter. In the operational amplifier 11, the voltage of the signal line 12 is applied to the positive phase input terminal through the input resistor 16,
The voltage of the operational amplifier 7 is also applied to one of the negative-phase input terminals via the input resistor 14. Therefore, the operational amplifier 11 is equivalent to comparing the maximum value of the output currents of the AC-DC converters with the instantaneous value of the output current of its own AC-DC converter, and these errors are signal-transmitted. It is transmitted to the means 8 and used for controlling the main circuit 10. In the main circuit 10, the error of the operational amplifier 11 is controlled to be zero. As a result, the output voltage of all AC-DC converters rises to make the current follow the maximum value. On the other hand, since voltage control that tries to keep the output voltage constant also works at the same time, the output currents of the AC-DC converters are all made uniform, and the output voltage does not deviate from the desired output voltage range. Absent. Hereinafter, the control method of making the output currents of the AC-DC converters described in this embodiment follow the maximum currents among them and equalize them will be referred to as the maximum current tracking control method.

This maximum current tracking control system differs from the average current tracking control system described in the embodiment of FIG. 3 in the case where a large number of AC-DC converters are operated in parallel to supply power to a load. This is the case when such a situation occurs. That is, for example, when one of the AC-DC converters has failed and its output current has decreased, one AC-DC converter has failed and
-Since the total output current of the DC converter decreases, it is necessary to increase the current of other AC-DC converters to compensate for this. However, in the average current tracking control method, the voltage of the signal line 12 becomes a voltage proportional to the average value of the output currents of all the AC-DC converters.
There is a problem that the voltage of 2 decreases and the current of other AC-DC converters that have not failed decreases. Therefore, in the average current tracking control method, in order to prevent the voltage drop of the signal line 12 when the AC-DC converter fails, the failure of the AC-DC converter is detected, and the failed AC-DC converter is detected from the signal line 12. It is necessary to take measures to separate it. On the other hand, in the maximum current tracking control method described in the present embodiment, when one of the AC-DC converters fails and its output current decreases, the voltage of the signal line 12 is affected by the decrease in this current. Never receive. Therefore, there is a feature that the currents of other AC-DC converters quickly rise to compensate for the currents of the failed AC-DC converters. As described above, the maximum current tracking control method described in this embodiment regarding the failure of the AC-DC converter is as follows.
Compared with the average current tracking control method, there is an advantage that no means for detecting a failure and disconnecting from the signal line 12 is required.

In this embodiment, the output currents of the AC-DC converters connected in parallel are detected by a simple circuit method, and the maximum value of the output currents of all the AC-DC converters is calculated, By detecting the error between the maximum value and the instantaneous value of the output current of its own AC-DC converter and feeding it back to the control circuit, it is possible to control the output current of all AC-DC converters uniformly. Becomes In addition, it is not necessary to prepare a special positive and negative voltage source as a voltage source for operating the operational amplifier, and there is no need for means for detecting a failure and disconnecting from the signal line 12 as compared with the average current tracking control method. It is possible to promote component saving, cost reduction, miniaturization, and the like. Note that although the present embodiment also describes an AC-DC converter that converts alternating current into direct current, this is also applicable to other configurations such as a DC-DC converter that converts direct current into direct current having a different voltage. It is also feasible.

Next, FIG. 5 is a circuit configuration diagram of a power supply device showing a fourth embodiment of the present invention, in which a plurality of AC-DC converters are connected in parallel as in FIGS. 3 and 4. Indicates. In FIG. 5, n units of AC-DC converters 2-1 to 2-n have exactly the same circuit configuration and are connected in parallel to the external AC power supply 1. This embodiment differs from the embodiment shown in FIG. 3 in that the positive power supply terminals of the operational amplifiers 7 and 11 are connected to the anode side of the diode 13 in FIG. Connected to the cathode side of the operational amplifier 11
The switching circuit 18 is connected between the negative-phase input terminal and the signal line 12, and the output terminal of the operational amplifier 11 is connected to the switching circuit 18. Other circuit configurations are exactly the same as those in FIG. is there. Therefore, the operation of the present embodiment due to this difference will be described below. In this embodiment, since the positive power supply terminals of the operational amplifiers 7 and 11 are connected to the cathode side of the diode 13, the AC-DC converter 2
If at least one of -1 to 2-n is operating, operational amplifiers 7 in all AC-DC converters,
The same voltage as that applied to the load 9 is applied to 11 to perform normal operation. As a result, for example, AC
Even when one of the -DC converters fails, the operational amplifiers 7 and 11 of the failed AC-DC converter operate normally. Further, in this embodiment, since the switching circuit 18 is connected between the negative-phase input terminal of the operational amplifier 11 and the signal line 12, when the AC-DC converter fails,
Open this switching circuit 18 to open another AC-D
Disconnect the failed AC-DC converter from the control of the C-converter. Here, in the present embodiment, the output of the operational amplifier 11 and the switching circuit 18 are connected, and when the output voltage of the operational amplifier 11 is out of the predetermined range for a predetermined period, it is determined that there is a failure, and the switching circuit is opened. Operates to open circuit 18. In the average current tracking control method, in order to prevent the voltage drop of the signal line 12 when the AC-DC converter fails, the failure of the AC-DC converter is detected, and the failed A
Although it is necessary to take measures to disconnect the C-DC converter from the signal line 12, according to the present embodiment, the failed AC-D is used.
AC that enables normal operation of the operational amplifiers 7 and 11 of the C converter, determines the operating state of the AC-DC converter based on the output voltage of the operational amplifier 11, and operates the AC-DC converter that has failed in parallel. -Can be separated from the control system of the DC converter. Further, as described in the present embodiment, the method of connecting the positive power supply terminals of the operational amplifiers 7 and 11 to the cathode side of the diode 13 at the output end of the AC-DC converter is also applied to the embodiment shown in FIG. It can be implemented similarly and the same effect can be obtained. Note that although the present embodiment also describes an AC-DC converter that converts alternating current into direct current, this is also applicable to other configurations such as a DC-DC converter that converts direct current into direct current having a different voltage. It is also feasible.

Next, FIG. 6 is a circuit configuration diagram of a power supply device showing a fifth embodiment of the present invention. As with FIGS. 3, 4 and 5, a plurality of AC-DC converters are connected in parallel. The connected configuration is shown. In FIG. 6, the AC-DC converter 2
The n units from -1 to 2-n have exactly the same circuit configuration and are connected in parallel to the external AC power supply 1. This embodiment is shown in FIG.
6 is different from the embodiment shown in FIG.
Is connected to the primary side of the transformer 19, the secondary side of the transformer 19 is connected to the rectifier circuit 20, the charge storage means 21 is connected to the output of the rectifier circuit 20, and the positive power supply of the operational amplifiers 7, 11 and 17 is connected. The terminal is connected to one end of the charge storage means 21, while in FIG. 4 the operational amplifiers 7, 11 and 1 are connected.
The positive power supply terminal 7 is connected to the anode side of the diode 13, and the other circuit configuration is exactly the same as in FIG. Therefore, the operation of the present embodiment due to these differences will be described below. In the present embodiment, the primary side of the external AC power supply 1 is connected to the primary side of the transformer 19,
Since the secondary side of the transformer 19 is connected to the rectifier circuit 20, a rectified DC voltage is output from the rectifier circuit 20 and the charge storage means 21 is connected, so that the DC voltage is smoothed. It This DC voltage is used for all AC-DC
It is applied to the operational amplifiers 7, 11 and 17 of the converter. As a result, the operational amplifiers 7, 11 and 17 operate regardless of the state of the AC-DC converter 2-1. Therefore, in this embodiment, the AC-DC converter 2
It is possible to detect and control the overcurrent state of the output current at the start-up of -1. In addition, AC-D
Even if the main circuit 10 of the C converter 2-1 fails, the outputs of the operational amplifiers 7, 11 and 17 do not malfunction. Further, according to the present embodiment, it is possible to supply a stable voltage to the operational amplifiers 7, 11 and 17, and this voltage source is used as the AC-DC converters 2-1 to 2-n.
By using a power source common to all of the above, the number of parts can be reduced and the cost can be reduced as compared with the positive / negative dual power source method which is a conventional circuit method. In addition, also in the embodiment shown in FIGS. 4 and 5, another power supply is provided as in this embodiment, and the operational amplifier 7,
A stable voltage can be supplied to 11. Further, although the present embodiment also describes the AC-DC converter that converts alternating current to direct current, this is also applicable to other configurations such as a DC-DC converter that converts direct current to direct current having different voltages. It is also feasible.

Next, FIG. 7 is a circuit configuration diagram of a power supply device showing a sixth embodiment of the present invention. As with FIGS. 3, 4, 5 and 6, a plurality of AC-DCs are provided. The structure which connected the converter in parallel is shown. In FIG. 7, n AC-DC converters 2-1 to 2-n have exactly the same circuit configuration and are connected in parallel to the external AC power supply 1. 22 is a feedback resistor, 23, 24 and 25 are resistors, 26 is a constant voltage means,
27, 28, 29 are input resistors, 30 is an operational amplifier, 31
Is resistance. The internal circuit of the AC-DC converter 2-1 will be described below. In this embodiment, the feedback resistor 22 is connected between the output terminal of the operational amplifier 11 and the negative phase input terminal. The output of the operational amplifier 11 is input to the negative phase input terminal of the operational amplifier 30 via the input resistor 28. A resistor 23 and a resistor 24 are connected in series between the anode side of the diode 13 and the ground terminal 51. The connection point between the resistors 23 and 24 is connected to the positive phase input terminal of the operational amplifier 30 via the input resistor 29. Further, a resistor 25 and a constant voltage means 26 are connected in series between the anode side of the diode 13 and the ground terminal 51. Here, the constant voltage means 26 can be simply realized by using a constant voltage diode (Zener diode). The connection point between the resistor 25 and the constant voltage means 26 is input to the negative phase input terminal of the operational amplifier 30 via the input resistor 27. The positive power supply terminal of the operational amplifier 30 is connected to the anode side of the diode 13, and the negative power supply terminal of the operational amplifier 30 is connected to the ground terminal 51. The output terminal of the operational amplifier 30 has a resistor 31
It is input to the signal transmission means 8 via. The circuit configuration of this embodiment is different from the embodiment of FIG. 4 in the above points.
The other circuit configuration is exactly the same as in FIG.

Therefore, the operation of the present embodiment due to these differences will be described below. A resistor 23 connected between the anode side of the diode 13 and the ground terminal 51.
The series body of the resistor 24 and the resistor 24 is a voltage dividing resistor that detects the output voltage of the AC-DC converter 2-1. On the other hand, the series body of the resistor 25 and the constant voltage means 26, which is also connected between the anode side of the diode 13 and the ground terminal 51, is a circuit for obtaining the reference voltage. Therefore, a voltage proportional to the instantaneous value of the output voltage of the AC-DC converter 2-1 is input to the positive-phase input terminal of the operational amplifier 30, and one of the negative-phase input terminals is supplied with the constant voltage means 26 as a reference voltage. A fixed constant voltage is applied. The operational amplifier 30 compares the instantaneous value of the output voltage of the AC-DC converter 2-1 with the reference voltage determined by the constant voltage means 26, and the AC-DC converter 2-
It operates as so-called voltage control in which the output voltage of 1 is controlled to be constant. However, since the output of the operational amplifier 11 is input via the input resistor 28 to the negative phase input terminal of the operational amplifier 30, it is determined by the constant voltage means 26 when the output of the operational amplifier 11 increases. The output of the operational amplifier 11 is added to the reference voltage. As a result, the signal line 12 is generated by the maximum current tracking control method described above.
The error compared with the maximum value of becomes the output of the operational amplifier 11 and controls the output voltage of the AC-DC converter 2-1. As described above, according to the present embodiment, the so-called voltage control that keeps the output voltage constant and the uniform output current of each AC-DC converter by the maximum current tracking control method, that is, the balance control, are performed with a simple circuit. It is possible to do and at the same time. In addition, also in this embodiment,
Although the AC-DC converter that converts alternating current to direct current is described, it goes without saying that this can be similarly realized for other circuit configurations such as a DC-DC converter that converts direct current to direct current having a different voltage. Is possible.

[0019]

As described in detail above, according to the present invention,
It has a current detection resistor connected between the low voltage side of the load and the low voltage side of the output of the main circuit of the power supply device, and at least one operational amplifier having a negative power supply electrode connected to the load side of the current detection resistor. As a result, the load current can be detected quickly and accurately without using a plurality of independent DC power supplies for operating the operational amplifiers as a power supply device and without configuring a complicated circuit. It is possible to achieve componentization, miniaturization, and cost reduction. Further, by calculating the average value of the output currents of the power supply devices connected in parallel and feeding back the error to the control circuit, it becomes possible to perform average current tracking control for uniformly controlling the output currents of all the power supply devices. Also,
Detects the output current of each power supply connected in parallel,
Calculate the maximum value of the output current of all power supplies,
By detecting the error between the maximum value and the instantaneous value of the output current of its own power supply and feeding it back to the control circuit, maximum current tracking control becomes possible, and as a result, the output current of all power supplies is controlled uniformly. It becomes possible to do. Further, by connecting the positive power supply terminal of each operational amplifier of each power supply device to the load side of the semiconductor respectively, when the power supply device fails, it is possible to operate the operational amplifier normally,
It is possible to determine the operating state of the power supply device by the output voltage of the operational amplifier and disconnect the failed power supply device from the control system of the power supply devices that are operated in parallel. Further, by providing a DC power supply different from the power supply device for supplying power to the load, and connecting the DC power supply to the positive power supply terminal of each operational amplifier of the power supply device to obtain the power supply of the operational amplifier. In addition to enabling stable voltage supply to the operational amplifier,
By using this voltage source as a power source common to all the power supply devices, it is possible to reduce the number of components and reduce the cost as compared with the conventional positive / negative dual power source method which is a circuit method. Further, constant voltage control and balance control can be performed at the same time by using so-called voltage control that keeps the output voltage of the power supply device constant, and by making the output current of the power supply device uniform by the maximum current tracking control, that is, balance control. It will be possible.

[Brief description of drawings]

FIG. 1 is a circuit configuration diagram of a power supply device showing a first embodiment of the present invention.

FIG. 2 is a circuit configuration diagram of a conventional power supply device.

FIG. 3 is a circuit configuration diagram of a power supply device showing a second embodiment of the present invention.

FIG. 4 is a circuit configuration diagram of a power supply device showing a third embodiment of the present invention.

FIG. 5 is a circuit configuration diagram of a power supply device showing a fourth embodiment of the present invention.

FIG. 6 is a circuit configuration diagram of a power supply device showing a fifth embodiment of the present invention.

FIG. 7 is a circuit configuration diagram of a power supply device showing a sixth embodiment of the present invention.

[Explanation of symbols]

 1 External AC Power Supply 2, 2-1 to 2-n AC-DC Converter 3 Current Detection Resistor 4 Feedback Resistor 5, 6 Input Resistance 7 Operational Amplifier 8 Signal Transmission Means 9 Load 10 Main Circuit 11 Operational Amplifier 12 Signal Line 13 Diode 14 Resistance 15 Diode 16 Input resistance 17 Operational amplifier 18 Switching circuit 19 Transformer 20 Rectifier circuit 21 Charge storage means 22 Feedback resistance 23, 24, 25 Resistance 26 Constant voltage means 27, 28, 29 Input resistance 30 Operational amplifier 31 Resistance 51 Ground terminal 52 DC output terminal 53 Negative power supply terminal 54 Output terminal 55 Positive phase input terminal 56 Reverse phase input terminal 57 Positive power supply terminal

Front page continued (72) Kenichi Onda Inventor Kenichi Onda 7-1, Omika-cho, Hitachi City, Ibaraki Hitachi Ltd. Hitachi Research Laboratory (72) Inventor Yasuo Abe No. 1 Kitano, Majo, Mizusawa-shi, Iwate Prefecture Hitachi Mizusawa Electronics (72) Inventor Katsunori Hayashi 2880 Kozu, Odawara City, Kanagawa Stock Company Hitachi Storage Systems Division

Claims (11)

[Claims] 1. A power supply device having a main circuit for supplying DC power to a load, comprising: a current detection resistor connected between a low voltage side of the load and a low voltage side of an output of the main circuit. At least one operational amplifier having a negative power supply electrode connected to the load side of the current detection resistor, and the voltage across the current detection resistor is detected using the operational amplifier. . 2. The power supply device according to claim 1, wherein a ground potential is applied to the positive phase input terminal of the operational amplifier and a voltage lower than the voltage of the negative power supply terminal is applied to the negative phase input terminal. 3. The operational amplifier according to claim 1 or 2, wherein the operational amplifier is capable of operating with a single power supply and has a characteristic that a minimum value of an in-phase input voltage is lower than 0V. Power supply. 4. The power supply device according to claim 1, wherein the positive power supply electrode of the operational amplifier is connected to the high voltage side of the output of the main circuit. 5. A power supply device having a main circuit for supplying DC power to a load, comprising: a current detection resistor connected between a low voltage side of the load and a low voltage side of an output of the main circuit. At least one operational amplifier having a negative power supply electrode connected to the load side of the current detection resistor, the voltage across the current detection resistor is detected using the operational amplifier, and at least the power supply device is provided. Two or more units are connected in parallel and have an average value detecting means for detecting an average value of the detection voltage output from the operational amplifier in each power supply device, and compare the average value with the detection voltage of each power supply device. Then
A power supply device, characterized in that the output voltage of each power supply device is changed according to these errors to make the output current of each power supply device uniform. 6. The average value detection means of the power supply device according to claim 5, is connected to the average value detection means of another power supply device via an opening / closing means, and the error continues for a predetermined period of time to a predetermined value. When exceeding the range, the power supply device is characterized in that the opening / closing means is opened to disconnect the power supply device from the average value detecting means of another power supply device. 7. A power supply device having a main circuit for supplying DC power to a load, comprising a current detection resistor connected between a low voltage side of the load and a low voltage side of an output of the main circuit. At least one operational amplifier having a negative power supply electrode connected to the load side of the current detection resistor, the voltage across the current detection resistor is detected using the operational amplifier, and at least the power supply device is provided. Two or more units are connected in parallel and have maximum value detecting means for detecting the maximum value of the detection voltages output from the operational amplifier in each of the power supply devices, the maximum value and the detection voltage of each of the power supply devices. And changing the output voltage of each of the power supply devices according to these errors to equalize the output current of each of the power supply devices. 8. The high voltage side of the output of the main circuit of each of the power supply devices is connected to the high voltage side of the load via a semiconductor, respectively. Power supply. 9. The power supply device according to claim 9, wherein the positive power supply terminal of each operational amplifier of each power supply device is connected to the load side of each semiconductor. 10. The method according to claim 5, further comprising a DC power supply different from a power supply for the purpose of supplying electric power to a load, and the DC power supply is used for each operation of the power supply. A power supply device for connecting to a positive power supply terminal of an amplifier to obtain a power supply for the operational amplifier. 11. The average value detecting means according to claim 5, further comprising means for detecting an output voltage output from a main circuit of the power supply device and means for generating a reference voltage. An error obtained by comparing the maximum value output by the average value or the maximum value detection means and the detection voltage output from the operational amplifier of each power supply device is added to the reference voltage,
The voltage obtained by the addition and the detected output voltage of the main circuit are compared, and the comparison result is transmitted to the main circuit through a signal transmission means to control the output voltage. Power supply.