JP3775251B2 - Multi-output power supply circuit and multi-output power supply method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a multi-output power supply circuit that can supply a plurality of voltages to a load, and more particularly to a power supply circuit that rationally controls an inrush current prevention operation at the start of supplying a plurality of power supply voltages.
[0002]
[Prior art]
Some power supply circuits used in electronic devices and apparatuses are provided with an inrush current control circuit for the purpose of protecting the own circuit and protecting the load at the start of voltage supply. For example, (A); Japanese Patent Laid-Open No. 03-027721 discloses such an inrush current control circuit. In the technology of this publication, the primary inrush current prevention circuit is activated in advance in the single power supply circuit, and when the secondary side output falls within a certain value after the power is turned on, the inrush current prevention is based on that information. It is configured to short-circuit the resistance for the prevention circuit in order to turn off the circuit.
[0003]
Further, (B); the power supply circuit disclosed in Japanese Patent Application Laid-Open No. 1-152921 is also provided with a resistor for limiting inrush current as a similar inrush current preventing circuit, and when the power is turned on, the resistor generates an inrush current. In a steady state, the solid state relay connected in parallel to the resistor is operated so that all the power supply current flows through the solid state relay. In this technology, noise generation at the time of switching is eliminated by using a solid state relay, thereby preventing malfunction of other electronic circuits. In this technology, the short circuit of the inrush current preventing resistor is performed based on the output voltage of the power source.
[0004]
In addition, (C); in the technology disclosed in Japanese Patent No. 2998201 (“power supply device”), an alternating current rectifier circuit, a smoothing capacitor provided on the output side of the rectifier circuit, and an input of the rectifier circuit AC current switching means provided on the side, and an inrush current detection means for detecting an inrush current provided between the rectifier circuit and the smoothing circuit, and when the detected value of the inrush current detection means exceeds a predetermined value, The inrush current is prevented by operating the alternating current switching means to limit the alternating current supplied to the rectifier circuit.
[0005]
By the way, in recent electronic devices and apparatuses, in order to pursue low power consumption, there are many devices that operate each function by supplying an optimum voltage for each part using a plurality of voltages. This flow extends to each load, the device used, and the device itself may require multiple voltage inputs. In addition, as a power supply corresponding to such an application, for example, (D); JP 2000-116127 A, (E); JP 2000-184713 A, (F); JP 2000-217356 A, A “multi-output DC / DC converter” is disclosed.
[0006]
In a device that operates with multiple voltages, if any one of the multiple power supply voltages required for the load section is not supplied and only another power supply voltage is supplied, the device may be destroyed, which may be protected. is necessary.
[0007]
As a countermeasure against this, it is possible to monitor the voltage of the power supply to be supplied individually on each load side and to stop the operation when the voltage is not supplied. It's not a good idea to invite an increase. For this reason, a countermeasure on the power source side is preferable.
As a countermeasure technique on the power source side, for example, (G); Japanese Patent Laid-Open No. 8-79971 discloses that a plurality of power source units driven by a common power source simultaneously start supplying power to different loads connected to each other at a predetermined voltage. A power supply apparatus configured as described above is disclosed. In the technique disclosed in the publication, when a power supply to a plurality of power supply units is turned on, a timer circuit connected to one of the plurality of power supply units starts measuring time, and each of a plurality of preset power supply units starts up. When the predetermined time required for the control can be measured, the control circuit controls the switch means to simultaneously start power supply to all the loads from the plurality of power supply units via the switch means.
[0008]
In addition, (H); Japanese Patent Application Laid-Open No. 8-317553 discloses a multiple output power supply circuit in which the rise and fall characteristics of plus and minus power supplies are symmetric to suppress the occurrence of click noise in the power supply circuit. Has been. In addition, (I); Japanese Patent Application Laid-Open No. 4-289725 ("Power-on / off circuit") also discloses that each power source composed of a plurality of DC / DC converters for the purpose of preventing destruction of a semiconductor integrated circuit serving as a load. A technique is disclosed in which the rising / falling of the output voltage of the DC / DC converter can be arbitrarily selected.
However, it is generally difficult to guarantee an accurate simultaneous output operation in a DC / DC converter (multi-output DC / DC converter) that is widely used as a power source as described above and can output a plurality of power source voltages. Further, in the event of a failure of the DC / DC converter, the simultaneous output operation cannot be guaranteed at all.
[0009]
As described above, the control by the inrush prevention circuit is generally used in a single power supply system and the like, and as described above, one recent device requires two types of input voltages. In some systems, it is preferable to provide an inrush prevention circuit. However, the power supply of such a system can be obtained by simply diverting an inrush current prevention technology that relies only on a single power supply as seen in each of the known technologies described above, and only knows the voltage state on one side. Therefore, it is highly possible that the device of the load will be damaged. Therefore, a technique suitable for this type of system is required.
[0010]
[Problems to be solved by the invention]
The present invention has been made in view of the actual situation relating to the multiple output power supply as described above, and simultaneously starts the supply of the power supply voltage to the load in a multi-output power supply circuit capable of supplying a plurality of voltages to a plurality of loads simultaneously. An object of the present invention is to provide a multi-output power supply circuit that appropriately performs an inrush current prevention operation at this time and does not damage a load device or the like.
[0011]
[Means for Solving the Problems]
In order to solve the problem, in the present invention, a multi-output power supply circuit is generated to supply a plurality of power supply outputs to a load by power input from a power supply means, and an input side of the multi-output power supply unit. When the power supply output is supplied from the multi-output power supply unit to the load, the current input from the power supply means to the multi-output power supply unit is not limited and the power supply output is supplied to the load. a rush current controller to limit the current input from the power supply means to the multiple-output power supply unit, the output voltage of each power supply output monitoring the plurality of individual output voltages of the power supply output is set respectively when not being Output voltage detecting means for detecting that supply is possible when the voltage exceeds a predetermined voltage, and the output voltage detection means provided between the plurality of power supply outputs of the multi-output power supply unit and the load. hand An output control unit that supplies simultaneously start to load the plurality of power supply output according to the detection output from the composing include.
[0012]
In the above configuration, a multi-output DC / DC converter is used for the multi-output power supply unit, and the output control unit includes a plurality of switch elements and each switch provided individually between the plurality of power supply outputs and a load. Output control means for simultaneously closing the elements, and the inrush current control section is connected to the inflow current limiting means whose both ends are connected to the power supply main and the input of the multi-output DC / DC converter, and this inflow You may comprise from the short circuit means which short-circuits both ends of a current limiting means based on the output of the said multiple output power supply main part supplied to the said load . That is, in the multiple output power supply method according to the present invention, an inrush current control unit is connected to the input side of the multiple output power supply unit, and the power supply is supplied when the multiple output power supply unit supplies the power output to the load. The current input from the power supply unit to the multi-output power supply unit is not limited, and when the power supply output is not supplied to the load, the current input from the power supply unit to the multi-output power supply unit is limited, and the plurality of power supplies The output voltage of the multi-output power supply unit is compared when each output voltage of the output is compared with each predetermined voltage, and when all the output voltages of the plurality of power supply outputs reach the predetermined voltage corresponding to each of the output voltages. The switch element connected between the load and the load is controlled to start supplying the plurality of power supply outputs to the load simultaneously.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
In the present invention, in a multi-output power supply circuit that supplies a plurality of voltages (electric power) to a load that requires a plurality of input voltages, it is an essential condition that voltages are supplied to the load at the same time. In order to cope with the case, means for detecting the state of each power supply voltage output is provided, and after determining that the respective voltages can be supplied simultaneously, the voltage is supplied to the load. Thus, the supply of a plurality of voltages to the load is started accurately and simultaneously, and an inrush current at that time is appropriately prevented. Further, when it is confirmed that the voltage is actually supplied to the load, the power supply path is switched so as to avoid the inflow current preventing means such as a resistor. This avoids heat generation by the inflow current prevention means and a reduction in circuit efficiency.
[0014]
[Embodiments] The present invention will be described in detail with reference to the drawings. Here, for simplicity of explanation, a power supply circuit with two types of voltage output will be described as an example. FIG. 1 is a block diagram showing a configuration of an embodiment of a multi-output power supply circuit according to the present invention. FIG. 2 is a flowchart for explaining the operation of the embodiment circuit, and FIG. 3 is a waveform diagram for explaining a change in circuit input current from the start of power supply in the embodiment circuit.
[0015]
Referring to FIG. 1, the multi-output power supply circuit of this embodiment includes a power supply means 1, an ON / OFF means 2, an inrush current control section 3, a multi-output DC / DC converter 4 as a multi-output power supply section, and an output voltage detection. Means 5 and an output control unit 7 are included. The inrush current control unit 3 includes an inflow current limiting unit 31 and a short circuit unit 32, and the output control unit 7 includes contacts 8 and 9 as switch elements and an output control unit 10.
[0016]
The power supply means 1 is a supply source for supplying power to the circuit. In portable devices and the like, a power battery corresponds to this. Further, in a device using a commercial power supply, for example, a power supply circuit unit that creates a known DC power supply including a transformer, a rectifier, and a smoothing circuit corresponds. The multi-output power supply circuit according to the present invention includes both a configuration having the power supply means 1 and a power supply means 1 as an external element.
[0017]
The ON / OFF means 2 is a main power switch for turning on / off a main power supply line, and uses a mechanical switch or an electronic switch.
[0018]
The inrush current control unit 3 is a control part that performs a protection function against an inrush current when the main power supply is turned on and when a voltage is supplied to the load. Both ends are connected to the power supply main and the input of the multi-output DC / DC converter. And a short circuit 32 for short-circuiting both ends of the resistor 31.
[0019]
The short-circuit means 32 shown in the figure is an electrically controllable switch element that can short-circuit both ends of the resistor 31 and has a capacity sufficient to pass a current supplied from the power supply means 1 during continuous operation of the multi-output power supply circuit. It is only necessary to form a path, and a semiconductor relay or an electromagnetic relay is used. The short-circuit means 32 forms the conductive path based on the output of the main part of the multi-output power source supplied from the multi-output power source part to the load (in the embodiment, any one output may be used) to form a resistor (inflow current) Preventing means) Both ends of 31 are short-circuited and invalidated. That is, the short-circuit means, and therefore the inrush current control unit, has a limit signal (which may be the output of the multi-output power supply main part supplied to the load itself) obtained based on the output of the multi-output power supply main part supplied to the load. The current supplied from the appropriate power supply means is not limited only in correspondence with the input state, but in other cases, the current supplied from the power supply means is limited. Therefore, the inrush current is limited (prevented) at the start of operation or when the voltage supply to the load is started.
[0020]
The multi-output DC / DC converter 4 as a multi-output power supply unit is a known circuit that inputs a DC voltage and outputs two kinds of voltages. For example, as mentioned above: (D); JP 2000-116127 A, (E); JP 2000-184713 A, (F); JP 2000-217356 A, and others Various multi-output DC / DC converters are also known. In the present invention, any configuration may be used. The two outputs of the multi-output DC / DC converter 4 are individually connected to corresponding loads via the output control unit 7. In the figure, reference numeral 6 denotes a load that requires simultaneous input of a plurality of voltages.
[0021]
The output voltage detection means 5 is a functional unit that detects whether two output voltages of the multi-output power supply unit can be supplied. In other words, the output voltage detection means 5 individually monitors the output voltages of the two types of outputs of the multi-output DC / DC converter 4 and detects when the output voltages of the respective power supply outputs all exceed a predetermined voltage. Detect and output. For example, it can be constituted by a comparator circuit that compares an input voltage connected to each of a plurality of output voltages (2 in the embodiment) with a predetermined reference voltage and a logic circuit that outputs an AND of the outputs of the respective comparator circuits.
[0022]
The output control unit 7 is connected to the output terminal of the output voltage detection means 4. The output control unit 7 is a functional unit that permits output to the load 6 in response to the detection output when the output voltage detection unit 5 determines that a plurality of voltages can be supplied simultaneously and the result is output.
[0023]
The output control unit 7 according to the embodiment includes an output control means 10 connected to the output terminal of the output voltage detection means 4 and contacts 8 and 9 driven by the output control means 10. One end of each of the contacts 8 and 9 is connected to each output of the multi-output DC / DC converter 4, and the other end is connected to a corresponding power supply terminal of the load 6. Actually, when a signal is sent from the output control means 10 to the contacts 8 and 9, the contacts 8 and 9 are simultaneously closed, and the respective voltage outputs are connected to the power supply terminals of the load 6 so that the respective voltages are supplied substantially simultaneously. The
[0024]
Next, the outline of the operation of this embodiment will be described with reference to FIG. In a power supply circuit that must simultaneously supply different voltages to the load, the output voltage detection means 5 monitors the voltage output from the secondary side of the multi-output DC / DC converter 4 that outputs a plurality of voltages, When it is detected that power can be supplied, a signal (detection signal) indicating that a plurality of voltages can be output is output.
[0025]
Next, based on the detection signal from the output voltage detection means 5, the contacts of the contacts 8 and 9 are closed by driving the output control means 10. Thereby, a plurality of voltage outputs are simultaneously supplied to the load 6. At this time, the overcurrent of the current supplied to the load is suppressed by the inrush current preventing means 31.
[0026]
Then, the voltage actually supplied to the load switches the switch of the short-circuit means 32 of the inrush current control unit 3, and the power supply means 1 from the power supply means 1 through a path passing through the inrush current prevention means 31. The supplied current is directly supplied to the multi-output DC / DC converter 4 without going through the inrush current preventing means 31.
[0027]
Thus, the short-circuit means 32 is set to select the path of the resistor 31 provided to prevent inrush current at the start of the power circuit operation, but the voltage is supplied to the load. Is confirmed, a path that passes through the resistor 31 is selected.
[0028]
Thereafter, the short-circuit means 32 maintains the switching state as long as the operation of the power supply circuit continues, and therefore the path passing through the resistor 31 is maintained. In this steady state, power is not consumed by the resistor 31, and heat generation and efficiency reduction of the power supply circuit are avoided.
[0029]
Note that the output control means 10 closes the contacts 8 and 9 and simultaneously outputs information that a predetermined voltage has been supplied to the load to the short-circuit means 32 of the inrush current control unit 3, whereby the short-circuit means 32. The same result can be obtained even if switching is performed.
[0030]
Hereinafter, the operation of the present embodiment will be described in more detail with reference to FIG. 1 and the flowchart of FIG. First, in the initial state (step: S201), the power supply means 1 in FIG. 1 is in a state in which voltage can be supplied, and the switch ON / OFF means 2 for supplying power to the circuit in FIG. 1 is in the OFF state. It is. In addition, the short-circuit means 32 is selected to prevent inrush current (inflow current limiting means: effective).
[0031]
When the ON / OFF means 2 of FIG. 1 is turned on (step: S202; YES) and the supply of power into the circuit is started, the inrush current is suppressed by the resistor 31 of FIG. The multi-output DC / DC converter 4 is supplied with power and outputs a predetermined voltage (step: S203). In step S202, if the ON / OFF means 2 in FIG. 1 is not turned on and remains in the OFF state, the initial state is maintained.
[0032]
When the ON / OFF means 2 is turned on (step: S202; YES), power is supplied to the multi-output DC / DC converter 4, and the multi-output DC / DC converter 4 is set to the secondary side at the set voltage value. Is supplied with power (step: S203).
[0033]
When power supply to the multi-output DC / DC converter 4 is started, the resistor 31 inserted on the input side of the multi-output DC / DC converter 4 functions to cause an excessive inrush current to flow. To prevent. That is, in the embodiment, as shown in the portion X in the waveform shown in FIG. 3, it is possible to suppress the portion of the inrush current x accompanying the power ON. This is effective in protecting the own circuit.
[0034]
The output voltage detection means 5 in FIG. 1 monitors two types of voltages supplied from the multi-output DC / DC converter 4 and determines that all voltages can be supplied (step: S204; YES). The controller 7 is requested to turn on the power supply line to the load 6 (step: S205). At this time, while the two types of voltage supply to the load are not possible (step: S204; NO), the output control unit 7 is not requested to turn on the power supply line until it becomes possible.
[0035]
1 receives a request for voltage supply from the output voltage detection means 5 to the load 6 (step: S205), the contact 8 and the contact 9 are closed and both voltage outputs are simultaneously supplied to the load (step S205). : S206).
[0036]
According to the present embodiment, two types of voltages are accurately supplied to the load at the same time, and there is no consideration for damaging the load. In addition, when the voltage supply to the load is started, the resistor 3 inserted on the input side of the multi-output DC / DC converter 4 functions to prevent an excessive inrush current from flowing. That is, as shown in the Y portion in the waveform shown in FIG. 3, it is possible to suppress the portion of the inrush current y at the start of voltage supply to the load. This is effective for protecting the own circuit and the load.
[0037]
As described above, when two types of voltages are supplied to the load 6 at the same time, the short-circuit means 32 shorts both ends of the resistor 31 using the voltage actually supplied to the load. A path passing through 31 is formed (resistor OFF), and the resistor 31 is substantially disconnected from the power supply line (step: S207).
[0038]
As described above, according to the multi-output power supply circuit of the present embodiment, a plurality of voltages can be simultaneously supplied to the load, and damage to the load can be prevented. Further, it is possible to prevent an inrush current when the loads are connected simultaneously, and the load can be protected from this aspect. Further, the inrush current can be reliably prevented by operating the inrush current control unit of FIG. 1 using the voltage actually supplied to the load to cancel the inrush current prevention function. For example, when there is a failure in the DC / DC converter, the inrush current prevention function is effective, and the load can be protected without voltage supply to the load. Since the resistor is disconnected during normal operation, there is no heat generation and no reduction in the efficiency of this circuit.
[0039]
In the embodiment of FIG. 1 described above, the case of DC input is described, and an example in which a multi-output DC / DC converter is used as a multi-output power supply unit is shown. However, the present invention is not limited to this, and various modifications are possible. For example, even when the power supply means 1 is a commercial AC power supply, the present invention can be implemented by using a multi-output power supply unit as a multi-output AC / DC converter. The present invention can also be applied to a power supply unit using a known transformer and rectifier circuit. In the embodiment, the multi-output DC / DC converter 4 is represented by an integrated configuration. However, a plurality of single-output power supplies are used and power is supplied to each input from a common voltage source. Needless to say, the resistors may be passed by detecting each output and confirming that the predetermined condition is satisfied.
[0040]
【The invention's effect】
According to the present invention, the following effects can be obtained. The first effect is that the supply can be started strictly at the same time when a plurality of voltages are supplied to the load. The second effect is that inrush current can be prevented when the voltage output is actually connected to the load simultaneously (at the start of supply). The third effect is that the inrush current can be surely prevented by operating the inrush current control unit using the voltage actually supplied to the load.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration of an embodiment of a multi-output power supply circuit according to the present invention.
FIG. 2 is a flowchart for explaining the operation of the embodiment circuit;
FIG. 3 is a waveform diagram illustrating a change in circuit input current from the start of power supply in the example circuit.
[Explanation of symbols]
1 ... Power supply means 2 ... ON / OFF means (main power switch)
3. Inrush current control unit 4. Multi-output DC / DC converter (multi-output power supply unit)
5 ... Output voltage detection means 6 ... Load 7 ... Output control unit 8 ... Contact 9 ... Contact 10 ... Output control means 31 ... Resistor (inflow current prevention means)
32 ... Short-circuit means (inrush current prevention function switching means)

Claims (3)

A multi-output power supply unit for generating a plurality of power supply outputs to a load by a power supply input from a power supply means;
It is connected to the input side of the multi-output power supply unit, and does not limit the current input from the power supply means to the multi-output power supply unit when the power output is supplied from the multi-output power supply unit to the load. An inrush current control unit for limiting a current input from the power supply unit to the multi-output power supply unit when the power output is not supplied to the load;
Output voltage detection means for monitoring individual output voltages of the plurality of power supply outputs, and detecting that the supply voltage can be supplied when the output voltage of each power supply output reaches a predetermined voltage or more, respectively;
An output control unit provided between the plurality of power supply outputs of the multi-output power supply unit and the load, and configured to start supplying the plurality of power supply outputs to the load simultaneously according to a detection output from the output voltage detection unit; ,
A multi-output power supply circuit comprising: The multi-output power supply unit is a multi-output DC / DC converter;
The output control unit comprises a plurality of switch elements individually provided between the plurality of power supply outputs and the load and output control means for simultaneously closing each switch element,
The inrush current control unit includes inflow current limiting means whose both ends are connected to the power supply means and the input of the multi-output DC / DC converter, and both ends of the inflow current limiting means are supplied to the load. ing from the short-circuiting means for short-circuiting based on the output of the multi-output power supply unit,
The multi-output power supply circuit according to claim 1. In a multi-output power supply method using a multi-output power supply unit that generates a plurality of power outputs by supplying power from a power supply means to a load,
  An inrush current control unit is connected to the input side of the multi-output power supply unit, and when the power output is supplied from the multi-output power supply unit to the load, the current input from the power supply means to the multi-output power supply unit Without limiting, when the power output is not supplied to the load, to limit the current input from the power supply means to the multi-output power supply unit,
  Comparing each output voltage of the plurality of power supply outputs with a predetermined voltage determined for each,
  When all the output voltages of the plurality of power supply outputs reach the predetermined voltage or more corresponding to each, the switch element connected between the output side of the multi-output power supply unit and the load is controlled to Start supplying multiple power outputs to the load simultaneously,
  And a multi-output power supply method.

Images