Power supply device

Abstract

To provide a technique capable of suppressing overcurrent or overvoltage when a power supply device is started up.SOLUTION: A power supply device comprises: a pre-stage voltage conversion device connected to a power supply; a post-stage voltage conversion device connected to the pre-stage voltage conversion device and a load; and a control device. The pre-stage voltage conversion device converts a voltage input from the power supply to output it to the post-stage voltage conversion device. The post-stage voltage conversion device converts a voltage input from the pre-stage voltage conversion device to output it to the load. The control device controls an output voltage of the pre-stage voltage conversion device on the basis of an output voltage of the post-stage voltage conversion device.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The technology disclosed in this specification relates to a power supply device. [Background technology]

[0002] A switching power supply device is disclosed in Patent Document 1. The switching power supply device of Patent Document 1 includes a first converter circuit that switches an input voltage to convert the voltage, a second converter circuit that switches a DC voltage generated by the first converter circuit to generate an output voltage, a first control circuit that controls the switching of the first converter circuit, and a second control circuit that controls the switching of the second converter circuit. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2001-320878 Summary of the Invention [Problem to be solved by the invention]

[0004] In the device of Patent Document 1, power factor correction is not performed when the output capacitor of the first converter circuit is sufficiently charged, and the second converter circuit in the subsequent stage may start operating while the power factor is still poor. As a result, the output of the second converter circuit may not increase sufficiently. In such a configuration, overcurrent or overvoltage may occur when the device starts up.

[0005] The present specification provides a technique that can suppress overcurrent and overvoltage when a power supply device is started up. [Means for solving the problem]

[0006] A first aspect of the present technology discloses a power supply device that supplies power from a power source to a load. The power supply device includes a pre-stage voltage conversion device connected to the power source, a post-stage voltage conversion device connected to the pre-stage voltage conversion device and the load, and a control device. The pre-stage voltage conversion device may convert a voltage input from the power source and output it to the post-stage voltage conversion device, the post-stage voltage conversion device may convert a voltage input from the pre-stage voltage conversion device and output it to the load, and the control device may control an output voltage of the pre-stage voltage conversion device based on an output voltage of the post-stage voltage conversion device.

[0007] According to this configuration, by controlling the output voltage of the pre-stage voltage conversion device based on the output voltage of the post-stage voltage conversion device, it is possible to suppress overcurrent and overvoltage when the power supply device is started up.

[0008] In a second aspect, in the first aspect, the control device may improve the power factor in the pre-stage voltage conversion device based on the output voltage of the post-stage voltage conversion device. With this configuration, it is possible to reduce power loss in the power supply device.

[0009] In a third aspect, in the first or second aspect, the post-stage voltage conversion device may include a transformer that transmits power from the input side to the output side. The control device may control the output voltage of the pre-stage voltage conversion device based on the output voltage of the post-stage voltage conversion device and a turns ratio of the transformer. This configuration makes it possible to suppress magnetic saturation of the transformer of the post-stage voltage conversion device.

[0010] In a fourth aspect, in any one of the first to third aspects, the post-stage voltage conversion device may include a delay circuit that delays the time it takes for the output voltage to reach a target voltage.

[0011] According to this configuration, by providing a delay circuit, it is possible to suppress overcurrent when the power supply device is started up, and it is also possible to use a post-stage voltage conversion device with a low allowable current.

[0012] In a fifth aspect, in any one of the first to fourth aspects, the load may be a secondary battery. The power supply device may be provided in a charging device that charges the secondary battery. With this configuration, it is possible to suppress overcurrent and overvoltage during charging of the secondary battery. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 1 is a block diagram of a power supply device according to an embodiment. [Figure 2] FIG. 4 is a sequence diagram showing an example of control by the control device. DETAILED DESCRIPTION OF THE INVENTION

[0014] A power supply device 2 of the embodiment will be described with reference to the drawings. As shown in Fig. 1, the power supply device 2 of the embodiment includes a pre-converter 10, a post-converter 20, and a control device 30. The power supply device 2 is electrically connected to a power source 50 and a load 60. The power supply device 2 is a device that relays power supplied from the power source 50 and supplies it to the load 60. The power supply device 2 can convert (step down or step up) the voltage input from the power source 50 and output it to the load 60.

[0015] The power supply 50 is, for example, a commercial power supply. The power supply 50 may also be a primary battery or a secondary battery. The power supply 50 in this embodiment is an AC power supply. In a modified example, the power supply 50 may be a DC power supply. The load 60 is, for example, a secondary battery (storage battery). The power supply device 2 may be provided in, for example, a charging device for charging the secondary battery. The load 60 may also be, for example, an electric motor or the like.

[0016] The pre-stage converter 10 is electrically connected to the power supply 50 and the post-stage converter 20. The input side (primary side) of the pre-stage converter 10 is connected to the power supply 50, and the output side (secondary side) of the pre-stage converter 10 is connected to the post-stage converter 20. The pre-stage converter 10 is, for example, a totem-pole PFC (Power Factor Correction) converter. The pre-stage converter 10 includes one or more switching elements (e.g., MOSFETs or IGBTs). The pre-stage converter 10 can convert (step down or step up) a voltage input from the power supply 50 and output the converted voltage to the post-stage converter 20. The pre-stage converter 10 can convert (step down or step up) a voltage by repeatedly turning on and off one or more switching elements. The pre-stage converter 10 of this embodiment is an AC-DC converter and can convert AC input from the power supply 50 to DC and output the converted voltage to the post-stage converter 20. In a modified example, the pre-stage converter 10 may be a DC-DC converter.

[0017] The pre-converter 10 may include a power factor correction circuit (not shown) for correcting the power factor in the pre-converter 10. The power factor correction circuit is, for example, an active circuit including one or more switching elements. The power factor correction circuit can be controlled by, for example, continuous mode control, discontinuous mode control, or boundary mode control.

[0018] The post-stage converter 20 is electrically connected to the pre-stage converter 10 and the load 60. The input side (primary side) of the post-stage converter 20 is connected to the pre-stage converter 10, and the output side (secondary side) of the post-stage converter 20 is connected to the load 60. The post-stage converter 20 is, for example, an LLC converter equipped with a resonant tank including an inductor and a capacitor. The post-stage converter 20 is equipped with one or more switching elements (for example, MOSFETs or IGBTs). The post-stage converter 20 can convert (step down or step up) the voltage input from the pre-stage converter 10 and output it to the load 60. The post-stage converter 20 can convert (step down or step up) the voltage by repeatedly turning on and off one or more switching elements. The post-stage converter 20 is a DC-DC converter that converts DC voltage.

[0019] The post-converter 20 includes a transformer 22 that transmits power from the input side (primary side) to the output side (secondary side). The post-converter 20 is an isolated converter in which the primary side circuit and the secondary side circuit are insulated via the transformer 22. The post-converter 20 may also include a delay circuit (not shown) that delays the time it takes for the output voltage of the post-converter 20 to reach a target voltage.

[0020] The control device 30 includes, for example, a CPU, a ROM, a RAM, etc., and executes control and processing related to the power supply device 2 according to a predetermined program. For example, the control device 30 controls the output voltage of the pre-converter 10 based on the output voltage of the post-converter 20.

[0021] FIG. 2 is a sequence diagram showing an example of control by the control device 30. As shown in FIG. 2, the control device 30 controls the pre-converter 10 and the post-converter 20 by executing a plurality of steps (ST). Specifically, in ST1, the control device 30 gradually increases the target voltage in the pre-converter 10 to approach a predetermined target voltage. The control device 30 also gradually decreases the command value of the drive frequency in the post-converter 20 to approach the predetermined command value. In a modified example, the control device 30 may gradually increase the command value of the drive frequency in the post-converter 20 to approach the predetermined command value.

[0022] Next, in ST2, the control device 30 controls the output voltage of the pre-converter 10 based on the output voltage of the post-converter 20. The control device 30 controls the output voltage of the pre-converter 10 by controlling one or more switching elements. The control device 30 may control the output voltage of the pre-converter 10 based on the output voltage of the post-converter 20 and the turns ratio of the transformer 22. The turns ratio of the transformer 22 is the ratio between the number of turns of the winding of the primary coil of the transformer 22 and the number of turns of the winding of the secondary coil (i.e., the number of turns of the winding of the primary coil of the transformer 22 / the number of turns of the winding of the secondary coil). Note that in ST2, the control device 30 fixes the command value of the drive frequency in the post-converter 20.

[0023] Furthermore, in ST2, the control device 30 may execute power factor correction control in the pre-converter 10 based on the output voltage of the post-converter 20. The control device 30 controls the switching elements of the power factor correction circuit of the pre-converter 10 based on the output voltage of the post-converter 20. The control device 30 may control the power factor correction circuit of the pre-converter 10 based on the output voltage of the post-converter 20 and the turns ratio of the transformer 22. The control device 30 may also control the power factor correction circuit of the pre-converter 10 based on the deviation of the output current of the post-converter 20.

[0024] Next, in ST3, the control device 30 calculates a target voltage for the pre-converter 10 based on the output voltage of the pre-converter 10. The control device 30 controls the pre-converter 10 so that the output voltage of the pre-converter 10 becomes the target voltage. The control device 30 may also execute power factor correction control for the pre-converter 10 based on the calculated target voltage. Note that in ST3, the control device 30 does not fix the command value of the drive frequency for the post-converter 20 but allows it to vary.

[0025] Next, in ST4, simultaneously with ST3 described above, the control device 30 controls the pre-converter 10 so that the output voltage of the pre-converter 10 becomes the target voltage. The control device 30 may also execute power factor correction control in the pre-converter 10 based on the calculated target voltage. In addition, in ST4, the control device 30 controls the post-converter 20 so that the output current of the post-converter 20 becomes the target current.

[0026] (effect) The power supply device 2 of the embodiment has been described above. As is clear from the above description, the power supply device 2 includes a pre-converter 10 (an example of a pre-stage voltage conversion device) and a post-converter 20 (an example of a post-stage voltage conversion device). The pre-converter 10 converts the voltage input from the power source 50 and outputs it to the post-converter 20. The post-converter 20 converts the voltage input from the pre-converter 10 and outputs it to the load 60. The control device 30 controls the output voltage of the pre-converter 10 based on the output voltage of the post-converter 20. This configuration makes it possible to suppress overcurrent and overvoltage when the power supply device 2 starts up.

[0027] The control device 30 improves the power factor in the pre-converter 10 based on the output voltage of the post-converter 20. With this configuration, the power loss in the power supply device 2 can be reduced.

[0028] The post-converter 20 includes a transformer 22 that transmits power from the input side to the output side. The control device 30 controls the output voltage of the pre-converter 10 based on the output voltage of the post-converter 20 and the turns ratio of the transformer 22. With this configuration, magnetic saturation of the transformer 22 of the post-converter 20 can be suppressed.

[0029] The post-converter 20 includes a delay circuit that delays the time it takes for the output voltage to reach the target voltage. With this configuration, the provision of the delay circuit makes it possible to suppress overcurrent at the start-up of the power supply device 2. Furthermore, a post-converter 20 with a low allowable current can be used.

[0030] The load 60 may be a secondary battery. The power supply device 2 may be provided in a charging device that charges the secondary battery. With this configuration, it is possible to suppress overcurrent and overvoltage during charging of the secondary battery.

[0031] Although specific examples of the present invention have been described in detail above, these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and variations of the specific examples exemplified above. The technical elements described in this specification or drawings exhibit technical utility alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. Furthermore, the technology exemplified in this specification or drawings can achieve multiple objectives simultaneously, and achieving one of these objectives itself has technical utility. [Explanation of symbols]

[0032] 2: power supply device, 10: pre-stage converter, 20: post-stage converter, 22: transformer, 30: control device, 50: power supply, 60: load

Claims

1. A power supply device that supplies power supplied from a power source to a load, a pre-stage voltage converter connected to the power supply; a post-stage voltage conversion device connected to the pre-stage voltage conversion device and the load; a control device; and the pre-stage voltage conversion device converts a voltage input from the power supply and outputs the converted voltage to the post-stage voltage conversion device; the post-stage voltage conversion device converts the voltage input from the pre-stage voltage conversion device and outputs the converted voltage to the load; The control device controls the output voltage of the pre-stage voltage conversion device based on the output voltage of the post-stage voltage conversion device.

2. 2. The power supply device according to claim 1, The control device improves the power factor in the pre-stage voltage conversion device based on the output voltage of the post-stage voltage conversion device.

3. 3. The power supply device according to claim 1 or 2, the post-stage voltage conversion device includes a transformer that transmits power from an input side to an output side, The control device controls the output voltage of the pre-stage voltage conversion device based on the output voltage of the post-stage voltage conversion device and a turns ratio of the transformer.

4. 3. The power supply device according to claim 1 or 2, The power supply device includes a delay circuit that delays the time it takes for the output voltage to reach a target voltage, wherein the post-stage voltage conversion device includes a delay circuit that delays the time it takes for the output voltage to reach a target voltage.

5. 3. The power supply device according to claim 1 or 2, the load is a secondary battery, The power supply device is provided in a charging device that charges the secondary battery.

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