JP2003032880A - Multioutput power supply circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a multioutput power supply circuit which can supply a plurality of voltages to a plurality of loads simultaneously, start supplying the power supply voltages to the loads simultaneously, and practice an operation for avoiding rush currents at the time of start to protect devices of the loads, etc., from damages. SOLUTION: This multioutput power supply circuit includes a multioutput power supply unit which supplies a plurality of power supply outputs to loads; a rush current preventing means which is connected to the input side of the multioutput power supply circuit, limits currents supplied from proper power supplying means, and may not limit a current according to an input of a limit control signal corresponding to the power supplied to the load; an output voltage detecting means which monitors the respective output voltages of the plurality of power supply outputs, and detects that the output voltages of the respective power supply outputs reach prescribed voltages determined respectively and outputs the detection result; a plurality of switches provided individually between the plurality of power supply outputs and the loads; and an intermittent output means which supplies the power supply outputs to the loads simultaneously and intermittently.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-output power supply circuit capable of supplying a plurality of voltages to a load, and more particularly to a power supply circuit adapted to rationally control an inrush current prevention operation at the start of supply of a plurality of power supply voltages. .

[0002]

2. Description of the Related Art Some power supply circuits used in electronic devices / equipment are provided with an inrush current control circuit for the purpose of protecting their own circuits and loads 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 the publication, the inrush current prevention circuit on the primary side is activated in advance in the single power supply circuit, and when the output on the secondary side falls within a fixed value after the power is turned on, the inrush current prevention is performed based on the information. Turn off the circuit
To prevent this, the resistance for the prevention circuit is short-circuited.

Further, (B); the power supply circuit disclosed in JP-A-1-152921 also has a resistor for limiting the inrush current as a similar inrush current prevention circuit, and the resistor is used when the power is turned on. The inrush current is limited, and in a steady state, the solid state relay connected in parallel with the resistor is operated so that all the power supply current flows through the solid state relay. In this technique, a solid-state relay is used to eliminate noise generation at the time of switching, thereby preventing malfunction of other electronic circuits. In this technique, the short circuit of the resistor for preventing the inrush current is performed based on the output voltage of the power supply.

In addition, in the technology disclosed in (C); Japanese Patent No. 2998201 ("power supply device"), a rectifier circuit for alternating current
A smoothing capacitor provided on the output side of the rectifier circuit; an alternating current switching means provided on the input side of the rectifier circuit; and an inrush current detection means provided between the rectifier circuit and the smoothing circuit for detecting an inrush current. When the detected value of the inrush current detecting means becomes equal to or more than a predetermined value, the alternating current switching means is operated to limit the alternating current supplied to the rectifier circuit to prevent the inrush current.

By the way, in recent years, in order to reduce the power consumption, many electronic devices / devices use a plurality of voltages to supply an optimum voltage to each part to operate each function. This flow extends to each load and used device, and the device itself may require a plurality of voltage inputs. As a power supply for such an application, for example, (D); Japanese Patent Laid-Open No. 2000-116127, (E); Japanese Patent Laid-Open No. 2000-184713.
No. 2000-217356, "Multiple Output DC"
/ DC converter "is disclosed.

In an apparatus operating with a plurality of voltages, if one of the plurality of power supply voltages required for the load is not supplied and only another power supply voltage is supplied, the device may be destroyed. Yes Protection required.

As a countermeasure against this, it is possible to individually monitor the voltage of the supplied power source on each load side to stop the operation when the voltage is not supplied. It is not a good idea because it will increase the circuit scale. Therefore, measures on the power supply side are preferable. As a countermeasure technique on the power supply side, for example, (G); Japanese Patent Laid-Open No. 8-79971 starts power supply at a predetermined voltage simultaneously to different loads connected to a plurality of power supply units driven by a common power supply. Such a power supply device is disclosed. In the technology 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 clocking, and each of the plurality of preset power supply units starts up. When the predetermined time required for the measurement can be measured, the control circuit controls the switch means to simultaneously start the power supply from each of the plurality of power supply units to each load via the switch means.

Further, (H); Japanese Patent Application Laid-Open No. 8-317553 discloses a multi-output power supply in which positive and negative power supplies have symmetrical rising and falling characteristics to suppress click noise in a power supply circuit. A circuit is disclosed. In addition, (I); Japanese Patent Laid-Open No. 4-289725 (“Power-on / off circuit”) also discloses a power supply composed of a plurality of DC / DC converters for the purpose of preventing destruction of a semiconductor integrated circuit as a load. Disclosed is a technique in which rising / falling of an output voltage of a DC / DC converter can be arbitrarily selected.
However, in a DC / DC converter (multi-output DC / DC converter) which is widely used as a power supply as described above and which can output a plurality of power supply voltages, it is generally difficult to guarantee accurate simultaneous output operation. In addition, DC / DC
In the event of a converter failure, simultaneous output operation cannot be guaranteed at all.

Further, as described above, the control by the inrush prevention circuit is generally used in a single power supply system or the like, and as described above, one device in recent years has two types of input voltage. It is preferable to provide an inrush prevention circuit even in a system requiring the above. However, for the power supply of such a system, as shown in each of the above-mentioned known technologies, by simply diverting the inrush current prevention technology that depends only on a single power supply, it is possible to grasp only one side voltage state and Since the state of the power supply voltage is ignored and the operation of the current protection circuit is stopped, there is a high possibility of causing a failure in the device of the load. Therefore, a technology suitable for this type of system is required.

[0010]

DISCLOSURE OF THE INVENTION The present invention has been made in view of the actual situation of the multiple output power source as described above,
In a multi-output power supply circuit that can supply multiple voltages to multiple loads at the same time, start power supply voltage supply to the loads at the same time, and properly perform the inrush current prevention operation at this time to damage the load devices, etc. It is an object of the present invention to provide a multi-output power supply circuit that does not have the above.

[0011]

In order to solve the problems, according to the present invention, a multi-output power supply circuit is connected to a multi-output power supply unit for supplying a plurality of power supply outputs to a load and an input side of the multi-output power supply unit. The current supplied from the appropriate power supply means is not limited in response to the state in which the limit signal obtained based on the output of the multi-output power supply main unit supplied to the load is input, but the limit signal When there is no input, an inrush current control unit that limits the current supplied from the power supply means and an individual output voltage of the plurality of power supply outputs are monitored to detect that the output voltage of each power supply output can be supplied. And an output control unit which is provided between the plurality of power supply outputs and the load, and which starts simultaneously supplying the plurality of power supply outputs to the load in accordance with the detection output from the output voltage detection unit. Including, configuration That.

In the above structure, a multi-output DC / DC converter is used for the multi-output power supply section, and the output control section is provided with a plurality of switch elements individually provided between the plurality of power supply outputs and the load. And an output control means for closing each switch element at the same time, and the inrush current control means has inflow current limiting means whose both ends are connected to the power supply main and the input of the multi-output DC / DC converter, respectively. And short-circuiting means for short-circuiting both ends of the inflow current limiting means on the basis of the output of the multi-output power supply main part supplied to the load, and the output voltage detecting means outputs the output voltage of each power supply respectively. It may be possible to detect that the supply has become possible when a predetermined voltage or more is reached.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION According to the present invention, in a multi-output power supply circuit for supplying a plurality of voltages (electric power) to a load that requires a plurality of input voltages, in particular, the voltages are simultaneously supplied to the loads. In order to deal with the case where it is an indispensable condition, a means for detecting the state of each power supply voltage output is provided, and after determining that each voltage can be supplied simultaneously, the voltage is supplied to the load. As a result, a plurality of voltages are started to be supplied to the load at the same time accurately, and an inrush current at that time is appropriately prevented. Further, if 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 prevention means such as a resistor. This avoids heat generation and circuit efficiency reduction due to the inflow current prevention means.

EXAMPLES The present invention will be described in detail below with reference to the accompanying drawings showing examples. Here, for simplification of description, a power supply circuit of two types of voltage output will be described as an example.
FIG. 1 is a block diagram showing the configuration of an embodiment of the multi-output power supply circuit of the present invention. 2 is a flow chart for explaining the operation of the embodiment circuit, and FIG. 3 is a waveform diagram for explaining changes in the circuit input current from the start of power supply in the embodiment circuit.

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, The output voltage detector 5 and the output controller 7 are included. The inrush current control unit 3 is composed of an inflow current limiting species 31 and a short-circuit means 32, and the output control unit 7 is composed of contacts 8 and 9 as switch elements and an output control means 10.

The power supply means 1 is a power source for supplying power to the circuit. In a portable device or the like, a power supply battery corresponds to this. Further, in a device that uses a commercial power source, a power source circuit unit that produces a known DC power source including, for example, a transformer, a rectifier, and a smoothing circuit corresponds. The multi-output power supply circuit of the present invention includes both a form including the power supply means 1 and a form using the power supply means 1 as an external element.

The ON / OFF means 2 turns on the main power supply line.
Main power switch to turn on / off, using a mechanical switch or electronic switch.

The inrush current control unit 3 is a control unit that has a function of protecting against inrush current when the main power is turned on and when voltage is supplied to the load, and both ends thereof are the power supply main and the multi-output DC / DC converter. Resistor 31 as inflow current control means connected to the input of
It comprises a short-circuit means 32 for short-circuiting both ends of.

The short-circuit means 32 in the figure is an electrically controllable switch element, which can short-circuit both ends of the resistor 31 and is sufficient to flow the 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 conductive path for capacitance,
A semiconductor relay or electromagnetic relay is used. The short-circuit means 32 forms the conductive path based on the output of the main body of the multi-output power source supplied to the load from the multi-output power source section (any one output in the embodiment) and forms a resistor (inflow current). Both ends of (prevention means) 31 are short-circuited and invalidated. That is, the short-circuit means, and hence the inrush current control unit, receives a limiting signal (which may be the output itself of the multi-output power supply main unit supplied to the load) obtained based on the output of the multi-output power supply main unit supplied to the load. The current supplied from the appropriate power supply means is not limited only in response to the input state, but in other cases, the current supplied from the power supply means is limited. Therefore, the rush current is limited (prevented) at the start of the operation or the voltage supply to the load.

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 types of voltages. For example, listed above: (D);
No. 00-116127, (E); JP 2000-184713, (F);
It is also disclosed in Japanese Patent Laid-Open No. 2000-217356, and other various multi-output DC / DC converters are known. The present invention may have any configuration. The two outputs of the multi-output DC / DC converter 4 are individually connected to the corresponding loads via the output control unit 7. In the figure, reference numeral 6 is a load that requires simultaneous input of a plurality of voltages.

The output voltage detecting means 5 is a multi-output power source unit 2
It is a functional unit that detects whether two output voltages can be supplied. That is, 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 when the output voltages of the respective power supply outputs all reach the predetermined voltage or higher. Detect and output. For example, it can be configured by a comparator circuit that compares the input voltage connected to each of the 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.

The output control section 7 includes the output voltage detecting means 4
Is connected to the output terminal of. The output control unit 7 is a functional unit that permits output to the load 6 corresponding to the detected output when the output voltage detection unit 5 determines that a plurality of voltages can be simultaneously supplied and outputs the result.

The output control section 7 of the embodiment comprises an output control means 10 connected to the output terminal of the output voltage detection means 4,
It is composed of contacts 8 and 9 driven by the output control means 10. One end of each of the contacts 8 and 9 is a multi-output DC
/ DC converter 4 is connected to each output, and the other end is connected to the 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 closed at the same time, each voltage output is connected to the power supply terminal of the load 6, and the respective voltages are supplied substantially at the same time.

Next, the outline of the operation of this embodiment will be described with reference to the same FIG. In the power supply circuit that must supply different voltages to the load at the same time, 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, and When it is detected that power can be supplied, a signal (detection signal) indicating that a plurality of voltages can be output is output.

Next, based on the detection signal from the output voltage detection means 5, the output control means 10 is driven to contact the contacts 8,
Close the contact of 9. As a result, 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 prevention means 31.

Then, the voltage actually supplied to the load switches the switch of the short-circuit means 32 of the inrush current control section 3, and the power supply means is provided by a path passing through the inrush current prevention means 31. The supply current from 1 is directly supplied to the multi-output DC / DC converter 4 without passing through the inrush current prevention means 31.

As described above, the short-circuit means 32 is set so as to select the path of the resistor 31 provided for preventing the inrush current at the start of the operation of the power supply circuit, but the above voltage is supplied to the load. When it is confirmed that
A path passing through the resistor 31 is selected.

After that, the short-circuit means 32 maintains the switching state as long as the operation of the power supply circuit continues, so that the path passing through the resistor 31 is maintained. In this steady state, resistor 3
1, the power is not consumed, and heat generation and a reduction in the efficiency of the power supply circuit are avoided.

The output control means 10 closes the contacts 8 and 9 and at the same time, outputs the information that a predetermined voltage is supplied to the load to the short-circuit means 32 of the inrush current control section 3, thereby Similar results can be obtained by switching the short-circuit means 32.

The operation of this embodiment will be further described below.
This 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 of FIG. 1 is in a state capable of supplying a voltage, and a switch ON / ON for supplying power to the circuit of FIG.
OFF means 2 is OFF. In addition, the short circuit means 32
The state to prevent inrush current is selected (inflow current limiting means: valid).

When the ON / OFF means 2 of FIG. 1 is turned on (step: S202; YES) and the supply of power to the circuit is started, after the rush current is suppressed by the resistor 31 of FIG. Similarly, power is supplied to the multi-output DC / DC converter 4 of FIG. 1 and a predetermined voltage is output (step: S203). In step S202, the ON / OFF means 2 shown in FIG. 1 is not turned on.
If it remains in the OFF state, it remains in the initial state.

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 keeps the set voltage value. Supply power to the secondary side (step: S
203).

When power supply to the multi-output DC / DC converter 4 is started, the multi-output DC / DC converter 4
The resistor 31, which is inserted on the input side of, functions to prevent an excessive inrush current from flowing. That is, in the embodiment, as shown in the X section in the waveform shown in FIG.
It is possible to suppress the portion of the inrush current x that accompanies N. This is effective in protecting the own circuit.

The output voltage detecting means 5 shown in FIG.
When the two types of voltage supplied from the DC / DC converter 4 are monitored and it is determined that all the voltages can be supplied (step: S204; YES), the power supply line to the load 6 is connected to the output control unit 7. Request to turn on (step: S205
). At this time, while two kinds of voltage cannot be supplied to the load (step: S204; NO), the output control unit 7 is not requested to turn on the power supply line until it becomes possible.

In the output control section 7 of FIG. 1, a request for voltage supply from the output voltage detecting means 5 to the load 6 (step: S205)
When the contact is received, the contacts 8 and 9 are closed and both voltage outputs are simultaneously supplied to the load (step: S206).

According to this embodiment, there is no concern that the two types of voltages will be supplied to the load exactly at the same time and that the load will be damaged. At the same time, when the voltage supply to the load is started, the multi-output DC
The resistor 3 inserted on the input side of the / DC converter 4 functions to prevent an excessive inrush current from flowing.
That is, as shown by 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 protection of the own circuit and protection of the load.

When two kinds of voltages are simultaneously supplied to the load 6 as described above, the short-circuit means 32 short-circuits both ends of the resistor 31 using the voltage actually supplied to the load. As a result, a path passing through the resistor 31 is formed (resistor OFF), and the resistor 31 is substantially disconnected from the power supply line (step: S207).

As described above, according to the multi-output power supply circuit of this embodiment, it is possible to supply a plurality of voltages to the load at the same time, and it is possible to prevent the load from being damaged. In addition, it is possible to prevent the inrush current when the loads are connected at the same time, and the load can be protected also from this aspect. Further, by using the voltage actually supplied to the load to operate the inrush current control unit in FIG. 1 to cancel the inrush current prevention function, it is possible to reliably prevent the inrush current. For example, when there is a failure in the DC / DC converter, the inrush current prevention function is effective, and voltage supply to the load does not occur, thus protecting the load. Note that during normal operation, the resistor is disconnected, so there is no heat generation or efficiency reduction of this circuit.

In the embodiment of FIG. 1 described above, the case of direct current input has been described, and an example using a multiple output DC / DC converter as the multiple output power supply section has been shown. But,
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 section as a multi-output AC / DC converter. The present invention can be applied to a power supply unit using a known transformer and rectifier circuit. Further, in the embodiment, the multi-output DC / DC converter 4 is shown as an integrated type, but a plurality of single-output power supplies are used and power is supplied to each input from a common voltage source, so that each single-output power supply is supplied. It goes without saying that the resistors may be passed after detecting each output and confirming that the predetermined condition is satisfied.

[0040]

According to the present invention, the following effects can be obtained. The first effect is that when a plurality of voltages are supplied to the load, it is possible to start the supply strictly at the same time. The second effect is that it is possible to prevent an inrush current when the voltage outputs are actually connected to the load at the same time (at the start of supply). The third effect is that it is possible to reliably prevent the inrush current by operating the inrush current control unit using the voltage actually supplied to the load.

[Brief description of drawings]

FIG. 1 is a configuration block diagram showing an embodiment of a multi-output power supply circuit of the present invention.

FIG. 2 is a flowchart illustrating an operation of an example 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 controller 4 ... Multi-output DC / DC converter (multi-output power supply section) 5 ... Output voltage detecting 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 (2)

[Claims] 1. A multi-output power supply unit for supplying a plurality of power output to a load, and a multi-output power supply unit connected to an input side of the multi-output power supply unit and supplied to the load. The current supplied from the appropriate power supply means is not limited only in response to the input of the limited signal, but the current supplied from the power supply means is limited without the input of the limited signal. A current controller, an output voltage detection unit that monitors the individual output voltages of the plurality of power supply outputs and detects that the output voltage of each power supply output is ready to be supplied, and between the plurality of power supply outputs and the load. A multi-output power supply circuit, comprising: an output control section which is provided in the output voltage detection means and starts simultaneously supplying the plurality of power supply outputs to the load in accordance with the detection output from the output voltage detection means. 2. The multi-output power supply unit is a multi-output DC / DC converter, and the output control unit includes a plurality of switch elements individually provided between the plurality of power supply outputs and a load and each switch element. The inrush current control unit has both ends connected to the power supply main and the input of the multi-output DC / DC converter, respectively, and the inflow current control unit. And a short-circuiting means for short-circuiting both ends of the means on the basis of the output of the multi-output power supply main part supplied to the load, wherein the output voltage detecting means is such that the output voltage of each power supply output is equal to or higher than a predetermined voltage determined individually. The multi-output power supply circuit according to claim 1, wherein the case of reaching is detected as being capable of supplying.