JPH08214546A - Dc power source and dc power supply system - Google Patents

Abstract

PURPOSE: To simplify the circuit configuration by so controlling an AC current waveform as to simulate to an AC voltage waveform, converting the AC voltage to a DC voltage, and converting it to a predetermined DC voltage. CONSTITUTION: The output voltage e1 of an input current correcting AC-DC converter (AD) 1 is fed back to output a constant voltage. A self-running type DC-DC converter (DD) 2 converts the DC voltage e1 to a high-frequency AC, voltage-converts it via a high-frequency power transformer, and outputs a rectified and smoothed DC voltage. Since the DD 2 does not have a function for stabilizing the output voltage, when the output current increases, it has impedance drop characteristics. Since the output voltage is proportional to the input voltage e1, en, if the output voltages e1, en of the AD 1 are not equal, its output voltage is shifted to a plurality. The current unbalance at the time of the parallel connection is decided according to the ratio of the output voltage deviation of the AD 1 to the impedance drop of the DD 2, and the ratio is effectively set to decide the intended current sharing.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic cash handling apparatus (A
utomatic teller machine (ATM), server computer, fault-tolerant computer, and other devices that require high reliability. The DC power supply device converts an AC current input from a commercial AC power supply into a DC current and outputs the DC current, and supplies electric power for operating the above-described device. A DC power supply device used for equipment requiring high reliability may be used by connecting one power supply circuit (DC power supply device) in parallel in order to increase output power or stabilize output power. Many. The DC power supply device of the present invention relates to a DC power supply device suitable for use in this redundant operation.

[0002]

2. Description of the Related Art Redundant operation in which one power supply circuit is connected in parallel is performed for the purpose of improving (stabilizing) the output current balance. FIG. 5 shows a conventional technique of a power supply device for redundant operation. The power supply circuit uses the input AC voltage (AC I
AC-DC converter for converting N) into a DC voltage and DC-D for converting the unstable and large DC voltage converted by the AC-DC converter 101 into a DC voltage of stable constant voltage and outputting the DC voltage.
It is composed of a C converter 102. As the DC-DC converter, an output voltage control DC-DC converter equipped with an output voltage feedback control circuit is used to output a constant voltage. To use this power supply circuit in a redundant configuration, in order to stabilize the output voltage (DC OUT) of the entire power supply device, the current output from each redundant power supply circuit is detected,
A balance control circuit (103) for controlling the output value of each power supply circuit according to the detected current value is required.

As a prior art document related to this redundant operation, there is Japanese Patent Publication No. 6-81502.

On the other hand, in the power supply device, reducing the harmonic current to the commercial power supply network and improving the power factor is one of the important issues.

A technique for preventing harmonic current is disclosed in, for example, Japanese Patent Laid-Open No.
No. 243058. This technology performs full-wave rectification of AC voltage on the AC-DC converter side of the power supply device, converts the voltage with a boost converter, and performs pulse width control so that the input voltage waveform becomes similar to the input voltage waveform. An input current correction circuit for this is provided (generally, the power factor correction circuit has the same configuration, and the output voltage is about 3
It is about 60v. In principle, the power factor correction circuit of this system can input both 100v system and 200v system of the AC input voltage, so the output of the boost converter is 360v.
The degree setting is enabled).

[0006]

Therefore, in the above-mentioned power supply device for performing redundant operation by parallel connection, an input current correction circuit is added to the AC-DC converter 101 when trying to improve the power factor, and the circuit configuration is improved. Becomes more complicated,
Accordingly, there is a problem that the price of the power supply device becomes high.

The object of the present invention is to suppress high frequency current,
It is to provide a DC power supply device suitable for redundant operation.

Another object of the present invention is to provide a direct current power supply system that enables harmonic operation and redundant operation for enhancing reliability.

[0009]

In order to make redundant operation an inexpensive DC power supply device with a reduced number of parts, each power supply circuit is configured as follows. That is, each power supply circuit
“An AC-DC converter (input voltage tracking type current control chopper that controls the current waveform of the input AC current to approximate the voltage waveform of the input AC voltage, converts the input AC voltage into a stabilized DC voltage, and outputs the DC voltage. Built-in converter) and this A
It is configured by a self-running DC-DC converter (current feedback type self-exciting inverter) which converts the DC voltage output from the C-DC converter into a DC voltage having a predetermined value and outputs the DC voltage.

By configuring the individual power supply circuits as described above, the output voltage of the power supply circuits is stabilized by utilizing the voltage stabilization function of the current control chopper, and the current balance between the individual power supply circuits during parallel operation is achieved. Is achieved by utilizing the self-balancing function by the impedance drop of the self-exciting inverter.

The applicant has confirmed by experiments that a highly reliable power source can be put into practical use by the operation of this power source device.

By connecting the above power supply circuits suitable for redundant operation in parallel, stable output can be realized by an inexpensive system with a reduced number of parts.

In the present invention, the AC-DC converter for controlling the current waveform of the input AC current to approximate the voltage waveform of the input AC voltage is a rectifier circuit for full-wave rectifying the input AC voltage, and the rectifier circuit thereof. And a conversion circuit for converting the DC voltage output from the rectifier circuit into a DC voltage having a predetermined value, and controlling the conversion circuit to approximate the current waveform of the input AC current to the voltage waveform of the input AC voltage. It is composed of a control circuit.

According to the present invention, a control circuit for balancing the output currents of the DC-DC converter is not required at all for the redundant operation unlike the prior art. Further, since there is no feedback control circuit for stabilizing the output voltage of each DC-DC circuit, the component saving is realized also from this point.

When the DC power supply device of the present invention is used to supply power to an ATM or the like, a battery is provided in addition to the AC power supply, and a charger for this battery is provided in excess of the required number to provide a spare unit. Thus, a DC power supply system with further improved reliability can be provided.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the drawings.

FIG. 1 shows the configuration of a DC power supply device connected in parallel according to an embodiment of the present invention. In FIG. 1, AC-IN indicates an AC input voltage. Generally 100V or 200V,
An alternating voltage of 50 Hz or 60 Hz is applied. Reference numeral 1 is an input current correction AC-DC converter. The details will be described later with reference to FIG. This AC-DC converter outputs a stable DC voltage (about 360V) e1. Reference numeral 2 is a self-propelled DC-DC converter which receives the e1 voltage and outputs an insulated necessary DC voltage VO. The details will be described later with reference to FIG.

When the output power is to be increased, the power supply circuit is connected in parallel at the AC input section and the DC output section to enable redundant operation. Although FIG. 1 shows an example of two parallel connections, a larger number of parallel connections may be used. 3 is a diode for improving reliability and maintainability.
It works effectively in redundant operation.

In this structure, a rectifier may be connected in series to the output of each power supply circuit in the forward direction to perform parallel redundant operation.

In the configuration shown in FIG. 1, the input current correction A
The output voltage e1 of the C-DC converter 1 is fed back by an internal control circuit (20 in FIG. 3) and stabilized to output a constant voltage even if the input voltage or the output current fluctuates. There is. Self-propelled DC-DC converter
The converter 2 converts the DC voltage e1 into high-frequency AC, converts the voltage via a high-frequency power transformer, and outputs a rectified and smoothed DC voltage. The self-propelled DC-DC converter 2 is a DC-DC converter that does not have the function of stabilizing the output voltage but has only the voltage conversion function. Therefore, the internal structure is extremely simple.

Next, the details of the DC power supply device will be described with reference to FIG.

In FIG. 3, 11 is an input current correction AC-DC converter, and 12 is a self-propelled DC-DC converter. The input current correction AC-DC converter 11 will be described in order.

The input AC voltage is an AC voltage input section (AC-I
N) 13 and full-wave rectified by a rectifier (D1-D4) 14. The transistor (Q1) 15, the reactor (L1) 16, the capacitor (C2) 17, the capacitor (C3) 18, and the diode 19 constitute a boost chopper circuit. Step-up chopper circuit is a well-known converter
In this circuit, the transistor 15 is turned on to store energy in the reactor 16, and the energy stored in the off period of the transistor 15 is transferred to the capacitors 17 and 18 through the diode 19.

The ON / OFF period of the transistor 15 is determined by the control circuit 20. The control circuit 20 includes a full-wave rectified voltage applied to the capacitor (C1) 21, a DC voltage applied to the capacitors 17 and 18, and a resistor (R1).
The voltage applied to 22, that is, the value obtained by converting the emitter current of the transistor 15 into a voltage value is input.

The control circuit 20 determines from these input voltage values that
The DC voltage applied to the capacitors 17 and 18 is constant so that the AC input voltage has a similar input current waveform (actually, the sawtooth current waveform is equalized by the capacitor 21). On / off control of the transistor 15 is performed so as to maintain the value.

Furthermore, the control circuit 20 also performs control so that the voltage applied to the resistor 22 does not become excessive (that is, the output current and input current of this power supply device do not become excessive).

Next, the self-propelled DC-DC converter 12 will be described. The self-propelled DC-DC converter shown in FIG. 3 is a current feedback type self-exciting inverter.

The transistor (Q3) 23 and the transistor (Q4) 24 are alternately turned on and off due to the saturation phenomenon of the saturable transformer (T1) 25. That is, when the transistor 23 is on, the base winding of the saturable transformer 25 on the transistor 23 side goes to the polarity mark side + (plus).
Potential is generated, and the transistor 23 remains on. The base current at this time is supplied as a current transformer effect from the current flowing from the emitter of the transistor 23 toward the transformer (T2) 26, that is, the load current through the saturable transformer 25. The transformer 25 maintains this state until its magnetic core is saturated, and at the moment of saturation, all polarities are inverted by the trigger action.

By this operation, the voltage across the capacitor 17 becomes the input voltage of the transformer 26 when the transistor 23 is turned on, and the voltage across the capacitor 17 becomes the input voltage when the transistor 24 is turned on. The capacitor (C4) 27 functions to prevent a direct current from flowing into the transformer 26, and an alternating voltage is applied only to a very small amount.

The secondary side of the transformer 26 is a rectifier (D6, D
7) It is rectified and smoothed by 28 and the capacitor 29 and output as a DC voltage. In this circuit diagram, the internal circuit of the control circuit, the starting circuit of the self-excited inverter, the surge absorption snubber, etc.
Not part of the circuit is shown.

In the power supply device of 300 W, 48 V output having this structure, the voltage deviation Δ of the AC-DC converter is 2%.
It was confirmed that the impedance drop δ of the DC-DC converter was 10%, and the parallel connection was possible with the output current imbalance within 20%. The output voltage accuracy is about 6%
Thus, it is a sufficient value as the voltage stability performance of the DC power bus.

When two parallel connections are made in the configuration shown in FIG. 1, the operation is as shown in FIG. Figure 2
In the figure, the horizontal axis represents current and the vertical axis represents voltage. Self-propelled DC-DC
The two converters 2 are arranged in parallel, and the output characteristics when the converters 2 are independent, that is, when the parallel connection is released, are shown by solid lines.

Since the self-propelled DC-DC converter 2 does not have a function of stabilizing the output voltage, it has a so-called impedance drop characteristic that the output voltage decreases as the output current increases. Also, the output voltage is the respective input voltage, e
Since the output voltage e1, en of the input current correction AC-DC converter 1 is not the same, the output voltage is shifted as shown in FIG. 2 because it is proportional to 1, en (including the impedance drop). It becomes two almost straight solid lines like this.

Here, the idea will be returned when the parallel connection as shown in FIG. 1 is made again. When the self-propelled DC-DC converters 2 are connected in parallel, the output voltage VO is shared,
The output current IO is the sum of the output currents I1 and In of the self-propelled DC-DC converters 2. That is, it stabilizes at the operating point indicated by the broken line in FIG.

This relationship is expressed by the following equation.

Here, the impedance that causes the impedance descent is defined as RO, and two self-propelled D
RO of the C-DC converter 2 is the same. Furthermore, the voltage conversion ratio of the self-propelled DC-DC converter 2 is set to A
And this is also the same.

VO = e1 * A-I1 * RO = en * A-In * RO (1) In / I1 = 1-((e1-en) * A) / (RO * I1) (2) where ( e1-en) / e1 is the output voltage deviation Δ (RO × I1) / (e1 × A) is the impedance drop
If δ, In / I1 = 1−Δ / δ (3) holds.

That is, the current imbalance in the parallel connection is the output voltage deviation of the input current correction AC-DC converter 1.
It is determined by the ratio of Δ to the impedance drop δ of the self-propelled DC-DC converter 2. Therefore, by appropriately setting this ratio, it becomes possible to determine the intended current sharing in parallel connection.

Although the above description has been made with two parallel connections, the current sharing can be determined by the same principle even if a larger number of parallel connections are made.

FIG. 4 shows a power supply system to which the power supply device of the present invention is applied.

In FIG. 4, the N + 1 front-end converter 30 is the power supply device shown in FIG.
Here are some examples. In this power supply system, the AC voltage input from the power supply plug 37 is converted into a stable DC voltage of 48 V by the N + 1 front end converter 30, and DC is converted.
Output to the 48V bus 38. The output DC voltage of 48 V is used for mechanical operations such as rotation of motors of ATM and servers. In addition, the DC48V bus 38
The DC-DC converter group 31 and the DC-DC converter group 32 are connected. The DC-DC converter group 31 converts a DC voltage of 48 V into a DC voltage of 5 V. DC
The DC converter group 32 supplies a DC voltage of 48 V to 3.
Convert to a DC voltage of 3 volts. Such a system provides the device with a DC voltage for various applications.

Two sets of batteries 34 are provided on the AC voltage input side.
And the battery charger 33 is connected. Power control unit 36
Controls the input voltage, and controls so as to supply power from the battery when power supply cannot be maintained sufficiently. In normal operation, the device to which the power supply system is connected has N power supply circuits of the front-end converter 30, M DC-DC converters 31 and DC-DC.
In the case of an apparatus that requires P converters 32 and L battery chargers 35, each of them has a configuration of one plus to further improve reliability.

[0043]

As described above, the input current correction A
By combining the C-DC converter and the self-propelled DC-DC converter, it is possible to provide a low-cost power supply system capable of reducing harmonics with a simple combination.

[Brief description of drawings]

FIG. 1 is a block diagram of a DC power supply device of the present invention having a redundant configuration.

FIG. 2 is a diagram showing output current and output voltage characteristics of the DC power supply device shown in FIG.

FIG. 3 is a diagram showing a detailed configuration of the DC power supply device shown in FIG.

FIG. 4 is a diagram showing a system to which the DC power supply device of the present invention is applied.

FIG. 5 is a diagram showing a conventional redundant DC power supply device.

[Explanation of symbols]

 1 Input current correction AC-DC converter 2 Self-propelled DC-DC converter 3 Rectifier 4 Load current

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masami Takahashi 1 120-120 Sachimachi Inazawa, Aichi Prefecture Chubu Hitachi Electric Co., Ltd.

Claims (11)

[Claims] 1. A DC power supply device for inputting an AC voltage and outputting a DC voltage, comprising: a rectifier circuit for full-wave rectifying the input AC voltage; a chopper circuit having a reactor and a first transistor; and a rectifier circuit for rectifying the rectifier circuit. The pulsating DC voltage after being applied, the emitter current of the first transistor, and the output voltage of the chopper circuit are detected, and the average value waveform of the emitter current of the first transistor is approximated to the waveform of the pulsating DC voltage. A DC-AC converter including a drive control circuit that drives the first transistor, a second transistor group that receives an output voltage from the chopper circuit, and a drive circuit for the second transistor group; It consists of an insulating transformer that receives the output from the second transistor group and converts the voltage value, and a circuit that rectifies and smoothes the output of the insulating transformer. DC power supply device being characterized in that a free-running inverter. 2. An AC for controlling a current waveform of an input AC current to approximate to a voltage waveform of an input AC voltage, converting the input AC voltage into a stabilized first DC voltage, and outputting the stabilized first DC voltage.
A DC power supply device comprising: a DC converter; and a free-running DC-DC converter that converts the first DC voltage into a second DC voltage having a predetermined value and outputs the second DC voltage. 3. A direct current power supply system comprising a plurality of direct current power supply devices according to claim 2 connected in parallel. 4. The DC power supply device according to claim 2, wherein the AC-DC converter is a rectifier circuit for full-wave rectifying the input AC current, and a rectifier circuit connected to the rectifier circuit for output from the rectifier circuit. A conversion circuit for converting the DC voltage of No. 3 into the first DC voltage having a predetermined value, and a control circuit for controlling the conversion circuit to approximate the current waveform of the input AC current to the voltage waveform of the input AC voltage. A DC power supply device comprising: 5. A direct current power supply system comprising a plurality of direct current power supply devices according to claim 4 connected in parallel. 6. A connecting portion for connecting to an AC power source, and a current waveform of an input alternating current, which is connected in parallel to the connecting portion and which is input from the connecting portion, is approximated to a voltage waveform of an input alternating voltage. An AC-DC converter that controls and converts the input AC voltage into a stabilized first DC voltage and outputs the converted DC voltage; and converts the first DC voltage into a second DC voltage having a predetermined value and outputs the second DC voltage. Direct-current power supply device including a self-running DC-DC converter, a direct-current power supply bus that receives parallel outputs from the plurality of direct-current power supply devices, and first and second DCs connected to the direct-current power supply bus. A DC power supply system, comprising: a DC converter. 7. The DC power supply system according to claim 6, further comprising a backup power supply. 8. The DC power supply system according to claim 7, further comprising a charger that charges the backup power supply with the power of the AC power supply. 9. The DC power supply system according to claim 8, wherein a plurality of the chargers are provided. 10. A rectifier circuit for rectifying an input AC current, and a first rectifier circuit connected to the rectifier circuit for converting a first DC voltage output from the rectifier circuit into a second DC voltage having a predetermined value. A conversion circuit, a control circuit for controlling the conversion circuit so that the current waveform of the input alternating current is approximated to the voltage waveform of the input voltage of the input alternating current, and an output of the conversion circuit different from the predetermined value A DC power supply device comprising: a second conversion circuit for converting to a voltage value of 1. and a smoothing circuit for rectifying and smoothing an output of the second conversion circuit. 11. A direct current power supply system comprising a plurality of direct current power supply devices according to claim 10 connected in parallel.