Power supply device

Abstract

To provide a power supply device capable of correcting current detection values of a plurality of power conversion devices without causing cost increase.SOLUTION: The power supply device includes a plurality of power conversion devices, a switching means for switching a connection state of the plurality of power conversion devices to a series connection or a parallel connection, and a control device, and when the plurality of power conversion devices are connected in series, the control device calculates a correction value of a current detection value of each power conversion device with respect to a total current detection value of each power conversion device, and corrects the current detection value of each power conversion device by the correction value.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a power supply device. [Background technology]

[0002] Patent Document 1 discloses a technology in which, when an AC signal is applied, the terminal current of a shunt resistor and the terminal current of a compensation resistor are detected, and the resistance value of the shunt resistor is corrected with the resistance value of the compensation resistor based on the first current detection value and the second current detection value. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2023-027567 Summary of the Invention [Problem to be solved by the invention]

[0004] The technique disclosed in Patent Document 1 requires connecting a signal application section and a high-precision resistor dedicated to correction separately from the path through which the current to be detected flows, which may lead to increased costs.

[0005] The present disclosure has been made in consideration of the above, and aims to provide a power supply device that can correct the current detection values ​​of multiple power conversion devices without increasing costs. [Means for solving the problem]

[0006] The power supply device according to the present disclosure comprises a plurality of power conversion devices, a switching means for switching the connection state of the plurality of power conversion devices between a series connection and a parallel connection, and a control device, and when the plurality of power conversion devices are connected in series, the control device calculates a correction value for the current detection value of each power conversion device relative to the total current detection value of each power conversion device, and corrects the current detection value of each power conversion device using the correction value. [Effects of the Invention]

[0007] According to the present disclosure, by utilizing the state in which multiple power conversion devices are connected in series, it is possible to obtain a correction value (gain error correction value) for the current detection value of each power conversion device relative to the total current detection value, thereby making it possible to correct each of the current detection values ​​of multiple power conversion devices without incurring an increase in costs. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a circuit diagram showing the configuration of a power supply device according to an embodiment, in which a plurality of power conversion devices are connected in series. [Figure 2] FIG. 2 is a circuit diagram showing the configuration of the power supply device according to the embodiment, in which a plurality of power conversion devices are connected in parallel. [Figure 3] FIG. 3 is a circuit diagram showing a configuration of a power supply device according to an embodiment in which a plurality of power conversion devices are connected in series and in parallel. [Figure 4] FIG. 4 is a flowchart showing the flow of a current correction method performed by the power supply device according to the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] A power supply device according to an embodiment of the present disclosure will be described with reference to the drawings. Note that the components in the following embodiments include those that are easily replaceable by those skilled in the art, or those that are substantially identical.

[0010] (power supply) The power supply device according to the embodiment is, for example, a charger for charging a battery (secondary battery) of an electric vehicle (BEV: Battery Electric Vehicle). Figures 1 and 2 show an example of the configuration of the power supply device according to the embodiment. Figure 1 shows a case in which a plurality of power conversion devices 11 are connected in series by a switching means 13 in the power supply device 1. Figure 2 shows a case in which a plurality of power conversion devices 11 are connected in parallel by the switching means 13 in the power supply device 1.

[0011] The power supply device 1 includes a plurality of power conversion devices 11, a power source 12, switching means 13, total current detection means 14, and a control device 15. Although Figures 1 and 2 show a case where there are two power conversion devices 11, the number of power conversion devices 11 is not particularly limited. The power supply device 1 is connected to a load 2, such as a battery of an electric vehicle.

[0012] The power conversion device 11 includes a switching circuit 111, a smoothing capacitor 112, and a current detection means 113. The current detection means 113 is a means for detecting the current output by each power conversion device 11.

[0013] The switching means 13 switches the connection state of the multiple power conversion devices 11 between a series connection and a parallel connection. Since the current that can be output by each power conversion device 11 is determined, once the total current to be output by the power supply device 1 (total output current) is selected, the switching means 13 switches the connection state of the multiple power conversion devices 11 between series and parallel in accordance with the selected total output current. In the power supply device 1, the total output current is changed by switching the connection state of the multiple power conversion devices 11 between series and parallel in this way.

[0014] The total current detection means 14 is a means for detecting the total current output by the power supply device 1. The control device 15 is realized by a processor such as a CPU (Central Processing Unit) and a memory (main storage unit) such as a RAM (Random Access Memory) or a ROM (Read Only Memory).

[0015] When a plurality of power conversion devices 11 are connected in series, the control device 15 calculates a correction value for the current detection value of each power conversion device 11 with respect to the total current detection value of each power conversion device 11, and corrects the current detection value of each power conversion device 11 using the correction value. Specifically, the control device 15 functions as current correction value calculation means 151, current correction means 152, and power conversion device control means 153.

[0016] When the multiple power conversion devices 11 are stopped, the current correction value calculation means 151 calculates a correction value for the offset error of the current detection means 113 provided in each of the power conversion devices 11 and a correction value for the offset error of the total current detection means 14. The offset error correction value may be calculated by performing zero point adjustment assuming that the current detection value before the power conversion devices 11 are started is 0 amperes as described above, or may be calculated by any other well-known method.

[0017] In addition, when multiple power conversion devices 11 are connected in series and operating, the current correction value calculation means 151 calculates a correction value for the gain error of each current detection means 113 with respect to the total current detection means 14 based on the following (1) to (4). (1) Current detection value of each current detection means 113 (2) Total current detection value of the total current detection means 14 (3) Correction value for offset error of each current detection means 113 (4) Correction value for the offset error of the total current detection means 14

[0018] When all of the multiple power conversion devices 11 are connected in series and in operation, the current correction value calculation means 151 calculates the ratio between a value obtained by correcting the offset error in the current detection value of each current detection means 113 and a value obtained by correcting the offset error in the total current detection value of the total current detection means 14. This makes it possible to calculate a correction value for the gain error in the current detection value of each current detection means 113 relative to the total current detection value.

[0019] 1, when all the power conversion devices 11 are connected in series, all the current detection means 113 measure the same current source. Therefore, in an operating state in which all the power conversion devices 11 output current, the ratio is calculated between the total current detection value whose offset error has been corrected by a conventional method (for example, zero point adjustment) and the current detection value of each current detection means 113 whose offset error has also been corrected.

[0020] This makes it possible to obtain a correction value for the gain error of the current detection value of each current detection means 113, with the offset error corrected, when the total current detection value with the offset error corrected is considered to be positive. Note that the detection error of the total current detection means 14 is smaller than the detection error of the current detection means 113 provided in each power conversion device 11. Furthermore, if the current detection means 113 has temperature characteristics, the correction values ​​for the offset error and gain error may be adjusted assuming the actual operating temperature.

[0021] Furthermore, the current correction value calculation means 151 acquires in advance correction values ​​for the offset error and gain error of the current detection value of each current detection means 113 when the total current detection value with the offset error corrected is considered to be correct. As a result, whether the power conversion device 11 is connected in series (see FIG. 1) or in parallel (see FIG. 2), the detection errors (gain errors) of the current detection means 113 are equal to each other and equal to the detection error (gain error) of the total current detection means 14.

[0022] The current correction means 152 corrects the current detection value of each current detection means 113 based on the correction value of the offset error of each current detection means 113 and the correction value of the gain error of the current detection value of each current detection means 113 with respect to the total current detection value. As a result, regardless of the series / parallel connection state of the power conversion device 11, the current detection value of each current detection means 113 can be corrected using the offset error correction value and gain error correction value calculated in advance.

[0023] If there is variation in the detection error of the current detection means 113 provided in each power conversion device 11, variation will occur in the output current of each power conversion device 11 when the power conversion devices 11 are connected in parallel (see FIG. 2). In the example of two power conversion devices 11 connected in parallel as shown in FIG. 2, even if the total current operates at less than twice the upper limit output current of each power conversion device 11, the power conversion device 11 with the higher output current may exceed the upper limit output current due to variation in the output current of the power conversion devices 11. In this way, if the power conversion device 11 exceeds the upper limit output current, a safety function such as throttling the output current or stopping operation is activated, resulting in the inconvenience of being unable to continue stable operation as a power supply device.

[0024] On the other hand, in the power supply device according to the embodiment, the detection errors (gain errors) of the current detection means 113 are equalized by the correction in the current correction means 152. Therefore, although the total current itself has a current error according to the detection error (gain error) of the total current detection value, the output currents of the power conversion devices 11 are equalized, so that the range of the total current that can be stably output can be expanded without the safety function operating.

[0025] Furthermore, based on the above principle, it is possible to grasp the error in the current detection value of each current detection means 113 when the total current detection value is considered to be correct. Therefore, for example, a sensor with a small error (i.e., an expensive sensor) can be used for the total current detection means 14, and a sensor with a large error (i.e., an inexpensive sensor) can be used for the current detection means 113 provided in each power conversion device 11. As a result, the cost of the entire power supply device 1 can be reduced.

[0026] The power conversion device control means 153 controls the plurality of power conversion devices 11 based on the current detection values ​​of the current detection means 113 included in each of the plurality of power conversion devices 11 corrected by the current correction means 152. In this way, by controlling the output current of each power conversion device 11 using the corrected current detection value of each power conversion device 11, it is possible to reduce variations in the output current of each power conversion device 11, particularly when connected in parallel (see FIG. 2).

[0027] 3 shows an example of a power supply device 1A in which a plurality of power conversion devices 11 are connected in both series and parallel. In this power supply device 1A, each pair of series-connected power conversion devices 11 (the pair of 1-1 and 2-1, the pair of 1-2 and 2-2) is set to an operating state in which current is output in sequence. This makes it possible to obtain a gain error correction value for the total current detection value in which the offset error has been corrected.

[0028] In this way, when there is a mixture of series and parallel connections of multiple power conversion devices 11, by setting the power conversion devices 11 one by one in sequence to an operating state in which they output current, it is possible to obtain a gain error correction value for the total current detection value corrected for the offset error.

[0029] (Current correction method) The flow of the current correction method performed by the power supply device according to the embodiment will be described with reference to FIG.

[0030] First, the current correction value calculation means 151 acquires the current of each power conversion device 11 from each current detection means 113 and acquires the total current from the total current detection means 14 (step S1). Next, the current correction value calculation means 151 calculates a correction value for the offset error of each current detection means 113 and a correction value for the offset error of the total current detection means 14, for example, by zero point adjustment or the like (step S2).

[0031] Next, the switching means 13 selects an output current and switches between series connection and parallel connection (step S3), and the operation of each power conversion device 11 starts (step S4). Next, the current correction value calculation means 151 determines whether each power conversion device 11 is connected in series or not (step S5).

[0032] In step S5, if it is determined that the power electronics devices 11 are connected in series (Yes in step S5), the current correction value calculation means 151 acquires the current of each power electronics device 11 from each current detection means 113 and acquires the total current from the total current detection means 14 (step S6). Subsequently, the current correction value calculation means 151 calculates a correction value for the gain error with respect to the total current detection value corrected for the offset error (step S7).

[0033] Next, the current correction means 152 corrects the current detection value of each power electronics device 11 using the gain error correction value (step S8), and completes this process. Note that, if it is determined in step S5 that the power electronics devices 11 are not connected in series (connected in parallel) (No in step S5), the current correction value calculation means 151 completes this process.

[0034] According to the power supply device of the embodiment described above, it is possible to obtain a correction value (gain error correction value) for the current detection value of each power conversion device 11 relative to the total current detection value by utilizing the state in which multiple power conversion devices 11 are connected in series. This makes it possible to correct each of the current detection values ​​of the multiple power conversion devices 11 without increasing costs, and to reduce detection errors in the output current.

[0035] Further advantages and modifications will readily occur to those skilled in the art. Thus, the invention in its broader aspects is not limited to the specific details and representative embodiments shown and described above. Accordingly, various modifications may be made without departing from the spirit or scope of the general inventive concept as defined by the appended claims and their equivalents. [Explanation of symbols]

[0036] 1,1A power supply 11 Power conversion device 111 Switching Circuits 112 Smoothing capacitor 113 Current detection means 12 Power supply 13 Switching Method 14 Total current detection means 15 Control device 151 Current correction value calculation means 152 Current correction means 153 Power conversion device control means 2. Load

Claims

[Claim 1] a plurality of power conversion devices; a switching unit for switching a connection state of the plurality of power conversion devices between a series connection and a parallel connection; a control device; Equipped with The control device When the plurality of power electronics devices are connected in series, a correction value of the current detection value of each power electronics device is calculated with respect to a total current detection value of each power electronics device; correcting the current detection value of each power conversion device using the correction value; power supply.

Images