JP2011188549A - Power unit, and method of controlling the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve conversion efficiency in a power unit, where a plurality of DC/DC converters are used. <P>SOLUTION: The power unit includes a plurality of DC/DC converters that convert a supply voltage to supply the same voltage to a load and can be operated in parallel. Some DC/DC converters are controlled so that other DC/DC converters are deactivated when a current supplied to the load is smaller than a prescribed value. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a power supply device and a control method thereof, and more particularly to a power supply device that supplies power to a load by a plurality of power supply units and a control method thereof.

  Conventionally, as a power supply device, a power supply device including a plurality of power supply units that can be switched between an on state and an off state in order to improve conversion efficiency is known. For example, Patent Document 1 includes a series regulator and a switching regulator that control the power supply output voltage to a constant level. The series regulator is selectively operated when the load current is small, and the switching regulator is selectively selected when the load current is large. A power supply system to be operated is described.

  Further, Patent Document 2 includes a plurality of power supply units that convert electric power from an AC power source into DC electric power and output it, and that can be switched between an on state and an off state. Each power supply unit is one of a plurality of drive modes having different characteristics of the power supply efficiency, which is the ratio of the output power to the power consumed to generate the output power of the power supply unit, with respect to the output power of the power supply unit. A power supply configured to be driven by two drive modes is described. In this power supply device, the power supply unit includes an AC / DC converter that converts input AC power into DC power and outputs the battery, and also outputs power output from the AC / DC converter in the first drive mode. It is comprised so that it may output, and it is comprised so that the electric power discharged from the battery in the 2nd drive mode may be output.

JP 2003-9515 A JP 2009-140138 A

  The following analysis is given in the present invention.

  In devices such as a CPU (Central Processing Unit), an NPU (Network Processing Unit), and an FPGA (Field Programmable Gate Array), a reduction in voltage and an increase in current are progressing. As a method of supplying power to such a device with a large current, a method of performing a parallel operation using a plurality of DC / DC converters is known. The reason why a plurality of DC / DC converters are used is that a DC / DC converter generates a current required by the device in one DC / DC converter because there is a limit to the current value that can be output by the internal components used. It is because it is not possible.

  Incidentally, the DC / DC converter has a characteristic that the conversion efficiency is poor when the load is small (light) as shown in FIG. For this reason, when a plurality of DC / DC converters are operated in parallel when the load is small, the conversion efficiency is very poor, and a large amount of power is wasted in the power supply device. On the other hand, the number of DC / DC converters used in parallel operation is selected as the number that can correspond to the maximum load of the device, but the state where the maximum load is reached in the device is very small, and one DC / DC in the steady state. In many cases, it can be supplied by a converter.

  However, in the power supply system of Patent Document 1, since the series regulator operates when the load current is small, sufficient conversion efficiency cannot be obtained. Moreover, since the power discharged from the battery is output when the load current is small, the power supply of Patent Document 2 cannot be applied to a power supply using only a DC / DC converter.

  Accordingly, an object of the present invention is to provide a power supply apparatus using a plurality of DC / DC converters, and a power supply apparatus that improves conversion efficiency when the load current is small, and a control method therefor.

  A power supply device according to one aspect of the present invention includes a plurality of DC / DC converters that can operate in parallel to convert a power supply voltage and supply the same voltage to a load, and some DC / DC converters include: When the current supplied to the load (referred to as load current) is smaller than a predetermined value, the other DC / DC converter is controlled to be deactivated.

  A control method for a power supply device according to another aspect of the present invention is a control method for a power supply device including a plurality of DC / DC converters capable of operating in parallel to convert a power supply voltage and supply the same voltage to a load. Some DC / DC converters are controlled so as to deactivate other DC / DC converters when the current supplied to the load is smaller than a predetermined value.

  According to the present invention, when the current supplied to the load is smaller than a predetermined value, the power is supplied to the load by only a part of the DC / DC converter, so that the conversion efficiency in the power supply device can be improved.

It is a block diagram which shows the structure of the power supply device which concerns on 1st Example of this invention. It is a block diagram which shows the structure of a DC / DC converter. It is a figure explaining the difference in the pulse width of a pulse signal. It is a figure which shows the relationship between the pulse width and load in a DC / DC converter. It is a block diagram which shows the structure of the power supply device which concerns on 2nd Example of this invention. It is a figure which shows the relationship between the load in a DC / DC converter, and efficiency.

  The power supply apparatus according to the embodiment of the present invention converts a power supply voltage (corresponding to VP in FIG. 1) and supplies the same voltage (corresponding to VLa in FIG. 1) to a load (corresponding to 15a in FIG. 1). A plurality of possible DC / DC converters, and some DC / DC converters (corresponding to 11a in FIG. 1) have other DC / DC converters when the current supplied to the load (referred to as load current) is smaller than a predetermined value. The DC converter (corresponding to 11b in FIG. 1) is controlled to be deactivated.

  In the power supply apparatus, the DC / DC converter operates based on pulse width modulation, and some DC / DC converters include a pulse monitoring function unit (23 in FIG. 2) that monitors the pulse width in the pulse width modulation. The pulse monitoring function unit outputs a control signal (Sca in FIG. 2) for inactivating another DC / DC converter when the pulse width corresponding to the load current supply period is narrower than a predetermined width. May be output.

  In the power supply device, the pulse monitoring function unit deactivates the other DC / DC converter when the pulse width corresponding to the load current supply period is narrower than the first time width, and corresponds to the load current supply period. When the pulse width is wider than the second time width wider than the first time width, a control signal for activating another DC / DC converter may be output to the other DC / DC converter.

  In the power supply device, a pulse width corresponding to 1/2 of the maximum load current may exist between the first and second time widths.

  In the power supply device, another DC / DC converter (corresponding to 11c in FIG. 5) that converts the power supply voltage and supplies the same voltage (corresponding to VLb in FIG. 5) to another load (corresponding to 15b in FIG. 5). The other DC / DC converter can supply another DC / DC converter (corresponding to 11b in FIG. 5) to another load when the current flowing to the other load is larger than a predetermined value. You may make it control.

  According to the power supply device as described above, when the current in the load circuit is small (the load is light), that is, when the current supplied to the load is smaller than a predetermined value, the other DC / DC converter is deactivated. By doing so, the conversion efficiency of the whole power supply device can be improved, and the power consumption in the power supply device can be reduced. Therefore, generation of excess heat in the power supply device can be suppressed.

  FIG. 1 is a block diagram showing a configuration of a power supply apparatus according to the first embodiment of the present invention. In FIG. 1, the power supply apparatus 10 includes DC / DC converters 11a and 11b. The DC / DC converters 11a and 11b operate based on pulse width modulation (PWM), receive the power supply voltage VP, and step down or boost the power supply voltage VP to supply the power supply voltage VLa to the load circuit 15a. The load circuit 15a is a device such as a CPU, for example.

  The DC / DC converter 11a has a function of monitoring the load state in the load circuit 15a. When the load is small (light), the DC / DC converter 11a deactivates (turns off) the operation of the DC / DC converter 11b by the control signal Sca, and supplies the power supply voltage VLa to the load circuit 15a only by the DC / DC converter 11a. Supply. When the load is heavy (heavy), the DC / DC converter 11a activates (turns on) the operation of the DC / DC converter 11b by the control signal Sca, and the DC / DC converter 11a and the DC / DC converter 11b The power supply voltage VLa is supplied to the load circuit 15a by parallel operation.

  FIG. 2 is a block diagram showing a configuration of the DC / DC converter 11a. In FIG. 2, the DC / DC converter 11a includes a pulse generation function unit 21, a switching function unit 22, a pulse monitoring function unit 23, a high-side transistor MN1, and a low-side transistor MN2.

  The pulse generation function unit 21 generates a pulse signal Sp that has been subjected to pulse width modulation based on the value of the power supply voltage VLa, and outputs the pulse signal Sp to the switching function unit 22 and the pulse monitoring function unit 23. The switching function unit 22 exclusively turns on and off the high-side transistor MN1 and the low-side transistor MN2 according to the level of the pulse signal Sp, and generates the power supply voltage VLa from the power supply voltage VP. The pulse monitoring function unit 23 monitors the load state in the load circuit 15a using the pulse signal Sp as an input signal, and outputs a control signal Sca for controlling on / off of the DC / DC converter 11b according to the load state.

  Next, the operation of the pulse monitoring function unit 23 will be described. The pulse monitoring function unit 23 monitors the load by monitoring the pulse width of the pulse signal Sp. When the load is large (heavy), the high level width (pulse width A) of the pulse signal Sp is widened as shown in FIG. On the other hand, when the load is small (light), the high-level width (pulse width B) of the pulse signal Sp is narrowed as shown in FIG.

  Pulse width A and pulse width B indicate the time for which the high-side transistor MN1 is turned on in each load state. The larger the load in the load circuit 15a, that is, the larger the current value flowing through the load circuit 15a, the longer the time during which the high side transistor MN1 is turned on. To make it longer (wider). The pulse monitoring function unit 23 monitors the load by monitoring the pulse width of such a pulse signal Sp.

  FIG. 4 is a diagram showing the relationship between the pulse width and the load in the DC / DC converter 11a. When the pulse width of the pulse signal Sp becomes larger (wider) than the pulse width C, the DC / DC converter 11a determines that the load of the load circuit 15a cannot be supplied only by the DC / DC converter 11a. A control signal Sca is output to turn on (activate) the operation of the / DC converter 11b. As a result, the DC / DC converter 11a and the DC / DC converter 11b operate in parallel to supply power to the load circuit 15a.

  On the other hand, when the pulse width of the pulse signal Sp becomes smaller (narrower) than the pulse width D, the DC / DC converter 11a or the DC / DC converter 11b can be operated in parallel from the DC / DC converter 11a alone. The control signal Sca is output in order to turn off (inactivate) the operation of the DC / DC converter 11b by determining that the load can be supplied.

  In the above operation, in order to cope with a sudden load fluctuation, the pulse width C is narrower than the pulse width corresponding to the maximum load, and wider than the pulse width corresponding to 1/2 of the maximum load, and the pulse width D is It is preferable to make the width narrower than the pulse width corresponding to 1/2 of the maximum load so that each has a margin.

  The power supply device 10 according to the present embodiment operates as described above, and when the load in the load circuit 15a is light, the power supply is supplied only by the DC / DC converter 11a to prevent the conversion efficiency of the power supply device 10 from being deteriorated. It is possible.

  FIG. 5 is a block diagram showing the configuration of the power supply apparatus according to the second embodiment of the present invention. In FIG. 5, the same reference numerals as those in FIG. The power supply device 10a further includes a DC / DC converter 11c and a switch SW with respect to the power supply device 10 of FIG.

  The DC / DC converter 11c has the same configuration as that of the DC / DC converter 11a, receives the power supply voltage VP, and steps down or boosts the power supply voltage VP to supply it to the load circuit 15b as the power supply voltage VLb. The load circuit 15b is a device such as a CPU, for example, similarly to the load circuit 15a. The power supply voltage VLb is the same as the power supply voltage VLa. The switch SW switches the state where the DC / DC converter 11b is connected to the load circuit 15a, the state where the DC / DC converter 11b is connected to the load circuit 15b, and the state where the DC / DC converter 11b is not connected anywhere.

  When the load of the load circuit 15a increases and the DC / DC converter 11a cannot supply the power supply voltage VLa to the load circuit 15a only by the DC / DC converter 11a, the operation of the DC / DC converter 11b by the control signal Sca is performed. And the switch SW is turned on to the load circuit 15a side to supply the power supply voltage VLa to the load circuit 15a using the DC / DC converters 11a and 11b. When the load of the load circuit 15a becomes small, the operation of the DC / DC converter 11b is turned off, and the connection with the load circuit 15a side in the switch SW is released.

  Further, in the DC / DC converter 11c, when the load of the load circuit 15b increases and the power supply voltage VLb cannot be supplied to the load circuit 15b only by the DC / DC converter 11c, the DC / DC converter 11b is controlled by the control signal Scb. And the switch SW is turned on to the load circuit 15b side to supply the power supply voltage VLb to the load circuit 15b using the DC / DC converters 11c and 11b. When the load of the load circuit 15b becomes small, the operation of the DC / DC converter 11b is turned off and the connection with the load circuit 15b side in the switch SW is released.

  When there are two load circuits, two sets of the power supply device 10 described in the first embodiment are required. However, there may be a device in which the load is not increased simultaneously with respect to the load circuits 15a and 15b. In such a case, power can be supplied by three DC / DC converters as in this embodiment, and in addition to reducing power consumption, the mounting area can also be reduced.

  In addition, three or more DC / DC converters corresponding to some DC / DC converters are controlled so that one other DC / DC converter can be operated in parallel when each load is heavy. You may make it comprise so that it may switch.

  Further, a plurality of other DC / DC converters are provided, and when the current supplied to the load is smaller than the same or different predetermined value, the other DC / DC converters are controlled to be deactivated. Good.

  It should be noted that the disclosures of the aforementioned patent documents and the like are incorporated herein by reference. Within the scope of the entire disclosure (including claims) of the present invention, the embodiments and examples can be changed and adjusted based on the basic technical concept. Various combinations and selections of various disclosed elements are possible within the scope of the claims of the present invention. That is, the present invention of course includes various variations and modifications that could be made by those skilled in the art according to the entire disclosure including the claims and the technical idea.

10, 10a Power supply devices 11a, 11b, 11c DC / DC converters 15a, 15b Load circuit 21 Pulse generation function unit 22 Switching function unit 23 Pulse monitoring function unit SW switch

Claims (6)

A plurality of DC / DC converters capable of operating in parallel to convert the power supply voltage and supply the same voltage to the load,
Some of the DC / DC converters control to inactivate other DC / DC converters when a current (referred to as load current) supplied to the load is smaller than a predetermined value. Power supply. The DC / DC converter operates based on pulse width modulation,
Some of the DC / DC converters include a pulse monitoring function unit that monitors a pulse width in pulse width modulation.
The pulse monitoring function unit outputs a control signal for inactivating another DC / DC converter to another DC / DC converter when a pulse width corresponding to the load current supply period is narrower than a predetermined width. The power supply device according to claim 1, wherein:   The pulse monitoring function unit deactivates the other DC / DC converter when the pulse width corresponding to the load current supply period is narrower than the first time width, and corresponds to the load current supply period. When a pulse width is wider than a second time width wider than the first time width, a control signal for activating another DC / DC converter is output to the other DC / DC converter. The power supply device according to claim 2.   4. The power supply device according to claim 3, wherein a pulse width corresponding to 1/2 of the maximum load current exists between the first and second time widths. Another DC / DC converter for converting the power supply voltage and supplying the same voltage to another load;
The another DC / DC converter controls the other DC / DC converter so that power can be supplied to the other load when a current flowing through the other load is larger than a predetermined value. The power supply device according to claim 1. A control method for a power supply device comprising a plurality of DC / DC converters capable of operating in parallel to convert a power supply voltage and supply the same voltage to a load,
Some of the DC / DC converters control to deactivate the other DC / DC converters when a current supplied to the load is smaller than a predetermined value. .

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