JP2663910B2 - Power supply - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to a power supply, and more particularly to a DC-DC power supply having a power factor improving circuit at an input portion of a switching power supply circuit.
The present invention relates to a converter type power supply device.

[0002]

2. Description of the Related Art In a switching power supply that is a DC-DC converter, an AC power supply is rectified and smoothed by a rectifier circuit composed of a diode and a capacitor, and the rectified and smoothed output is switched by a switching element to switch the primary side of a transformer. And a converter circuit for converting the secondary side output of the transformer to DC again by a rectifying and smoothing circuit including a diode, a choke coil and a capacitor.

In such a converter circuit, when the voltage of the AC power supply decreases, the on-time of the switching element for the converter increases and the transformer saturates. In order to prevent this, various proposals have been made. For example, a so-called dead time control for forcibly controlling the on-time of switching, and a method of monitoring an input current and reducing the output voltage when the input current increases. There is a control method.

Further, in Japanese Patent Application Laid-Open Nos. Hei 3-31617 and Hei 2-285961, the drive circuit of a switching element is turned off in response to a decrease in input voltage, and the operation of the converter itself is stopped. Technology has also been proposed.

On the other hand, a method of adding a power factor improvement circuit to the input of a switching power supply has been used as a power factor improvement measure. This power factor correction circuit has a rectifier circuit for rectifying an AC input, and a rectified output, and has a PFC (power factor correction) unit composed of a choke coil, a switching element, and a diode. Is an input of a DC-DC converter which is a switching power supply. An example of a power supply device having such a PFC circuit is disclosed in Japanese Patent Application Laid-Open No. 53-5755 and is well known.

The output voltage of the PFC circuit is determined by a control circuit in the PFC circuit. The output voltage is boosted to a set voltage without being influenced by the AC input voltage.
Control to decrease the pressure is performed. A stable output voltage is generated from the converter unit which receives the set voltage.

Further, recently, a power supply system has been employed in which a plurality of switching power supplies are operated in parallel to supply power to a common load. In such a power supply system, a PFC circuit is added to each of a plurality of switching power supplies, and a power supply control unit controls all of these switching power supplies systematically.

[0008]

In a conventional switching power supply to which a PFC circuit is not added, when an input voltage is low, a dead time control, an output voltage control by an input current monitor, and a circuit off control are performed. Although the method is adopted as described above, even if such a conventional control method is applied to a switching power supply to which a PFC circuit is added, since the voltage is controlled to be boosted to a set voltage by the PFC circuit, the converter section requires However, there is a disadvantage that the above control method cannot cope with this.

In a power supply device of the type to which a PFC circuit is added, when the input voltage is low, the on-time of the switching element in the PFC circuit becomes long, the magnetic material becomes saturated, and the current increases, so that each element is turned off. However, there is a disadvantage that components are destroyed due to an increase in temperature loss. If a component having a large tolerance is selected to prevent this destruction, an increase in space, an increase in cost, an increase in weight, and the like are caused.

Further, in a power supply system composed of a plurality of switching power supplies, there is a problem that control circuits and components are increased, costs are increased, and the like because of a configuration in which an AC input voltage is individually detected and controlled.

[0011]

A power supply device according to the present invention comprises a rectifier for rectifying an AC power supply, a power factor improving means having the rectified output as an input, and a DC having an output of the power factor improving means as an input. A power supply apparatus comprising: a DC converter means; a monitoring means for monitoring a decrease in the rectified output to generate an alert signal; and the power factor improving means and the DC-DC converter means in response to the alarm signal. And off-control means for turning off the power.

Another power supply according to the present invention comprises first to n-th power supplies.
(N is an integer of 2 or more) and a control circuit that operates with the output voltage of the first power supply circuit to control the entire apparatus, and each of the power supply circuits other than the first power supply circuit A power supply apparatus for supplying power to a load in parallel by an output voltage, wherein the first power supply circuit includes a rectifier for rectifying an AC power supply, and a power factor improving unit having the rectified output as an input. And D which receives the output of the power factor improving means as an input.
C-DC converter means, monitoring means for monitoring the decrease in the rectified output to generate an alert signal, and off control for turning off the power factor improving means and the DC-DC converter means in response to the alarm signal Means, and each of the second to n-th power supply circuits includes a rectifier for rectifying an AC power supply, a power factor improving unit having the rectified output as an input,
DC-DC converter means for receiving the output of the power factor improving means as input, wherein the control circuit responds to the stop of the output voltage from the first power supply circuit, It has an off command means for generating an off command for each of the circuits.

Still another power supply according to the present invention comprises
A power supply circuit other than the first power supply circuit, the power supply circuit including an n-th (n is an integer of 2 or more) power supply circuit, and a control circuit that operates by an output voltage of the first power supply circuit and controls the entire device; A power supply unit configured to supply power to a load in parallel with each output voltage of the power supply, wherein the first power supply circuit comprises: a rectifier for rectifying an AC power supply; and a power factor having the rectified output as an input. Improving means, DC-DC converter means having an input of the output of the power factor improving means as input, monitoring means for monitoring a decrease in the rectified output to generate an alert signal, and responding to the alarm signal, Improvement means and the DC-DC
Off control means for controlling the converter means to off,
Each of the second to nth power supply circuits includes a rectifier for rectifying an AC power supply, a power factor improving unit having the rectified output as an input, and a DC-DC converter having an output of the power factor improving unit as an input. Means, and the control circuit has off command means for generating an off command for each of the second to nth power circuits in response to an alarm signal from the first power circuit. And

Another power supply according to the present invention comprises first to n-th power supplies.
(N is an integer of 2 or more) and a control circuit that operates with the output voltage of the first power supply circuit to control the entire apparatus, and each of the power supply circuits other than the first power supply circuit A power supply apparatus for supplying power to a load in parallel by an output voltage, wherein the first power supply circuit includes a rectifier for rectifying an AC power supply, and a power factor improving unit having the rectified output as an input. And D which receives the output of the power factor improving means as an input.
C-DC converter means, and monitoring means for monitoring a decrease in the rectified output to generate an alarm signal,
To n-th power supply circuits each include rectifying means for rectifying AC power, power factor improving means having the rectified output as an input, and DC-DC converter means having the output of the power factor improving means as an input. Wherein the control circuit has off command means for generating all off commands for the first to nth power circuits in response to an alarm signal from the first power circuit.

[0015]

In a power supply having a rectifier circuit for rectifying an AC input, a PFC (power factor correction) circuit having the rectified output as an input, and a converter circuit having the PFC circuit output as an input, the rectified output is monitored. Then, when it drops, P
Turn off the FC circuit and the converter circuit.

In a power supply system of a system in which a plurality of power supply devices (each having a PFC circuit) are operated in parallel, a circuit for monitoring a rectified output is provided in one power supply device.
Based on this monitoring result, the PFC circuits and the converter circuits of all the power supplies are turned off.

[0017]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a block diagram of a power supply device according to an embodiment of the present invention. In the figure, an AC input 1 is rectified and smoothed by a rectifier circuit 2 and supplied to a PFC circuit 3. This P
The output of the FC circuit is input to the converter circuit 4 having a switching power supply circuit configuration, becomes a desired DC voltage output, and is supplied to a load (not shown).

A low voltage monitoring circuit 5 for monitoring the voltage of the rectified and smoothed output of the rectifying circuit 2 to turn on and off the circuit is provided. The low voltage monitoring circuit 5 includes an input voltage monitoring circuit 51 and an on / off control circuit 52.

The input voltage monitoring circuit 51 constantly monitors the rectified and smoothed output voltage, and generates alarm signals 100a and 100b when this voltage falls below a predetermined level. The alarm signal 100a is an alarm for an internal circuit, and the alarm signal 100b is an alarm for notifying an external circuit, and is the same signal.

The on / off control circuit 52 responds to the internal alarm signal 100a by the PFC circuit 3 and the converter circuit 4.
, And also derives the off command 200c to an external circuit. These off commands 200a to 200c are assumed to be the same signal.

When the input voltage is low, the input voltage monitoring circuit 51
, It is detected that the level has dropped below the reference level, and an alarm signal 100a (100b) is generated and supplied to the on / off control circuit 52. Therefore, the ON / OFF control circuit 52 issues an OFF command to stop the operations of the PFC circuit 3 and the converter circuit 4 (200a, 200b).

FIG. 2 is a block diagram of another embodiment of the present invention in which a power supply system composed of a plurality of power supplies is constructed using the power supply device of FIG. The power supply A has the same configuration as the power supply device shown in FIG. 1, but does not require an external alarm signal 100b and an on / off signal (off command) 200c.

The other power sources a1 to an are composed of the rectifier circuit 2, the PFC circuit 3, and the converter circuit 4 in the configuration of FIG. 1, and the low voltage monitoring circuit 5 is not added. The outputs of the power supplies a1 to an supply the power to the load 10 in parallel, and the output of the power supply A supplies the voltage of the power control unit 9.

The power supply control unit performs various controls of the entire system, and has a function of generating an off command for the power supplies a1 to an in accordance with the procedure shown in FIG. .

That is, when the low voltage monitoring circuit 5 of the power supply A detects that the input voltage has dropped below the reference level, the PFC circuit 3 and the converter circuit 4 in the power supply A are turned off. The power supply to 9 is cut off and stopped. When the power supply control unit 9 detects this power supply stop (step 31), the power supply a1
Then, an off command for .about.an is generated (step 32), and the operation of all the power supplies a1 to an is stopped.

In this case, even if the power supply from the power supply A is stopped, the power supply control unit 9 supplies power necessary for performing the operation of the procedure shown in FIG. 3 to internal power storage means (capacitor, backup battery, etc.). Can be supplied.

FIG. 4 is a block diagram of still another embodiment of the present invention, and the same parts as those in FIG. 2 are denoted by the same reference numerals.
Also in this example, the power supply A has the same configuration as that of FIG. 1, but does not require an external off command 200c.

In this example, when the low voltage monitoring circuit 5 of the power supply A detects that the input voltage has dropped below the reference level, the alarm signals 100a and 100b are output from the input voltage monitoring circuit 51. Alarm signal 100b
The power control unit 9 having received the power supply a in accordance with the procedure shown in FIG.
1 to an off instructions are generated.

That is, when the alarm signal 100b from the power source A to the outside is detected (step 41), the power sources a1 to al are detected.
An off command for an is generated (step 42), and the operation of all the power supplies a1 to an is stopped. In this case, in power supply A, an internal alarm signal 100a is generated, and in response to this, an on / off control circuit 52 (see FIG. 1)
Is an instruction 200 for turning off the PFC circuit 3 and the converter circuit 4
a, 200b, and the operation of the power supply A is stopped.
a, after a certain time delay, off commands 200a, 200
b is generated.

That is, since the power supply control unit 9 receives the power supply from the power supply A, the power supply A may generate the power supply for the time necessary for performing the operation of the processing procedure of FIG. It depends on what you need.

FIG. 6 is a block diagram of still another embodiment of the present invention, and the same parts as those in FIGS. Although the configuration of the power supply A is the same as that of FIG. 1 in this example, the on / off control circuit 52 does not need to be provided, and the PFC circuit 3 of the power supply A and the converter The circuit 4 is stopped.

The low-voltage monitoring circuit 5 of the power supply A detects a drop in the input voltage and outputs an external alarm signal 100b.
Is generated, the power supply control unit 9 responds to the alarm signal 100b as shown in FIG.
1) Generate an instruction to turn off the power supply A as well as the power supplies a1 to an (step 62).

[0034]

As described above, according to the present invention, the off-control is performed by monitoring the input voltage to the PFC circuit. There is an effect that the destruction of the parts can be prevented.

In a system composed of a plurality of power supplies, all the power supplies are not provided with an input voltage monitoring function, but are provided in a single power supply, and the other power supplies are turned off according to the monitoring result. By doing so, it is possible to significantly reduce the number of parts and reduce costs.

[Brief description of the drawings]

FIG. 1 is a block diagram of one embodiment of the present invention.

FIG. 2 is a block diagram of another embodiment of the present invention.

FIG. 3 is an operation flowchart of a power control unit 9 of the block of FIG. 2;

FIG. 4 is a block diagram of still another embodiment of the present invention.

FIG. 5 is an operation flowchart of the power supply control unit 9 of the block in FIG. 4;

FIG. 6 is a block diagram of another embodiment of the present invention.

FIG. 7 is an operation flowchart of the power supply control unit 9 of the block of FIG. 6;

[Explanation of symbols]

 Reference Signs List 1 AC power supply 2 Rectifier circuit 3 Power factor correction (PFC) circuit 4 Converter circuit 5 Low voltage monitoring circuit 9 Power supply control unit 10 Load 51 Input voltage monitoring circuit 52 ON / OFF control circuit A, a1 to an power supply

Claims (5)

(57) [Claims] 1. A power supply apparatus comprising: rectifying means for rectifying an AC power supply; power factor improving means for inputting the rectified output; and DC-DC converter means for inputting the output of the power factor improving means. Monitoring means for monitoring the decrease in the rectified output to generate an alert signal; and off-control means for off-controlling the power factor improving means and the DC-DC converter means in response to the alarm signal. A power supply device characterized by the above-mentioned. 2. The apparatus according to claim 1, further comprising a first to n-th (n is an integer of 2 or more) power supply circuits, and a control circuit which operates by an output voltage of said first power supply circuit and controls the entire apparatus. A power supply device configured to supply power to a load in parallel with each output voltage of a power supply circuit other than the first power supply circuit, wherein the first power supply circuit includes: a rectifier that rectifies an AC power supply; Power factor improving means having a rectified output as input, DC-DC converter means having an output of the power factor improving means as input, monitoring means for monitoring a decrease in the rectified output to generate an alarm signal; OFF control means for turning off the power factor improving means and the DC-DC converter means in response to a signal, wherein each of the second to nth power supply circuits includes a rectifying means for rectifying an AC power supply; Power factor improvement using this rectified output as input And a DC-DC converter unit that receives an output of the power factor improving unit as an input, wherein the control circuit responds to a stop of an output voltage from the first power supply circuit, and A power supply device comprising: off command means for generating an off command for each of the n power circuits. 3. A power supply circuit comprising: first to n-th (n is an integer of 2 or more) power supply circuits; and a control circuit which operates by an output voltage of the first power supply circuit and controls the entire apparatus. A power supply device configured to supply power to a load in parallel with each output voltage of a power supply circuit other than the first power supply circuit, wherein the first power supply circuit includes: a rectifier that rectifies an AC power supply; Power factor improving means having a rectified output as input, DC-DC converter means having an output of the power factor improving means as input, monitoring means for monitoring a decrease in the rectified output to generate an alarm signal; OFF control means for turning off the power factor improving means and the DC-DC converter means in response to a signal, wherein each of the second to nth power supply circuits includes a rectifying means for rectifying an AC power supply; Power factor improvement using this rectified output as input And a DC-DC converter unit that receives an output of the power factor improving unit as an input, wherein the control circuit responds to an alarm signal from the first power supply circuit, and A power supply device comprising an off command means for generating an off command for each of the power supply circuits. 4. A power supply circuit comprising: first to n-th (n is an integer of 2 or more) power supply circuits; and a control circuit which operates by an output voltage of the first power supply circuit and controls the entire apparatus. A power supply device configured to supply power to a load in parallel with each output voltage of a power supply circuit other than the first power supply circuit, wherein the first power supply circuit includes: a rectifier that rectifies an AC power supply; Power factor improving means having a rectified output as input, DC-DC converter means having an output of the power factor improving means as input, and monitoring means for monitoring a decrease in the rectified output and generating an alert signal. Each of the second to n-th power supply circuits includes a rectifier for rectifying an AC power supply, a power factor improving unit having the rectified output as an input, and a DC-DC having an output of the power factor improving unit as an input. And a control means, wherein the control circuit comprises: A power supply device comprising: off command means for generating all off commands for the first to nth power circuits in response to an alarm signal from a power circuit. 5. The DC-DC converter means has a switching power supply circuit configuration.
4. The power supply device according to any one of 4.