Power supply device

Abstract

To provide a power supply device capable of correcting voltage detection values of a plurality of power conversion devices.SOLUTION: The power supply device includes a plurality of power conversion devices, 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 parallel, the control device calculates a correction value of a voltage detection value of each power conversion device with respect to a total voltage detection value of each power conversion device, and corrects the voltage 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 a correction coefficient is calculated from the total voltage obtained by adding the voltages detected for each cell and the total voltage obtained by directly detecting the total voltage at the terminals of the battery pack, and the total voltage is corrected by multiplying this correction coefficient by the total voltage. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2007-033320 Summary of the Invention [Problem to be solved by the invention]

[0004] In the technology disclosed in Patent Document 1, the power sources (battery cells) are connected in series, making it difficult to correct detection errors in the voltage of each power source, and there is room for improvement.

[0005] The present disclosure has been made in view of the above, and has an object to provide a power supply device that can correct voltage detection values ​​of a plurality of power conversion devices. [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 parallel, the control device calculates a correction value for the voltage detection value of each power conversion device relative to the total voltage detection value of each power conversion device, and corrects the voltage 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 parallel, it is possible to obtain a correction value (gain error correction value) for the voltage detection value of each power conversion device relative to the total voltage detection value, thereby making it possible to correct each of the voltage detection values ​​of the multiple power conversion devices. [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 parallel. [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 series. [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 voltage 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 parallel 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 series 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 voltage 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 voltage detection means 113. The voltage detection means 113 is a means for detecting the voltage output by each of the power conversion devices 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. Because the voltage that can be output by each power conversion device 11 is determined, once the total voltage to be output by the power supply device 1 (total output voltage) 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 voltage. In the power supply device 1, the total output voltage is changed by switching the connection state of the multiple power conversion devices 11 between series and parallel in this way.

[0014] The total voltage detection means 14 is a means for detecting the total voltage 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 parallel, the control device 15 calculates a correction value for the voltage detection value of each power conversion device 11 relative to the total voltage detection value of each power conversion device 11, and corrects the voltage detection value of each power conversion device 11 using the correction value. Specifically, the control device 15 functions as voltage correction value calculation means 151, voltage correction means 152, and power conversion device control means 153.

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

[0017] Furthermore, when a plurality of power conversion devices 11 are connected in parallel and operating, the voltage correction value calculation means 151 calculates a correction value for the gain error of each voltage detection means 113 relative to the total voltage detection means 14 based on the following (1) to (4). (1) Voltage detection value of each voltage detection means 113 (2) Total voltage detection value of the total voltage detection means 14 (3) Correction value for offset error of each voltage detection means 113 (4) Correction value for the offset error of the total voltage detection means 14

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

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

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

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

[0022] The voltage correction means 152 corrects the voltage detection value of each voltage detection means 113 based on the correction value of the offset error of each voltage detection means 113 and the correction value of the gain error of the voltage detection value of each voltage detection means 113 relative to the total voltage detection value. As a result, regardless of the series / parallel connection state of the power conversion device 11, the voltage detection value of each voltage 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 voltage detection means 113 provided in each power conversion device 11, variation will occur in the output voltage of each power conversion device 11 when the power conversion devices 11 are connected in series (see FIG. 2). In the example of two power conversion devices 11 connected in series as shown in FIG. 2, even if the total voltage operates at or below twice the upper limit output voltage of each power conversion device 11, the variation in the output voltage of the power conversion devices 11 may cause the power conversion device 11 with the higher output voltage to exceed the upper limit output voltage. In this way, if the power conversion device 11 exceeds the upper limit output voltage, a safety function such as throttling the output current or stopping operation will be 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 voltage detection means 113 are equalized by the correction in the voltage correction means 152. Therefore, although the total voltage itself has a voltage error corresponding to the detection error (gain error) of the total voltage detection value, the output voltages of the power conversion devices 11 are equalized, and the range of the total voltage that can be stably output can be expanded without the safety function operating.

[0025] Furthermore, by using the above principle, it is possible to grasp the error in the voltage detection value of each voltage detection means 113 when the total voltage 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 voltage detection means 14, and a sensor with a large error (i.e., an inexpensive sensor) can be used for the voltage 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 multiple power conversion devices 11 based on values ​​obtained by correcting the voltage detection values ​​of the voltage detection means 113 included in each of the multiple power conversion devices 11 using the corrected values, in this way, for the voltage detection values ​​of each power conversion device 11, thereby making it possible to reduce variations in the output voltages of the power conversion devices 11, particularly when connected in series (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 parallel-connected power conversion devices 11 (the pair of 1-1 and 1-2, the pair of 2-1 and 2-2) is set to an operating state in which a voltage is output in sequence. This makes it possible to obtain a gain error correction value for a total voltage detection value in which offset error has been corrected. However, if each power conversion device 11 has a smoothing capacitor 112 on the output side, when switching between parallel-connected pairs (the pair of 1-1 and 1-2, the pair of 2-1 and 2-2), it is necessary to discharge the remaining charge in the smoothing capacitor 112 to set the output voltage to 0 volts.

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

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

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

[0031] Next, the switching means 13 selects an output voltage and switches between series connection and parallel connection (step S3), and the operation of each power conversion device 11 starts (step S4). Next, the voltage correction value calculation means 151 determines whether each power conversion device 11 is connected in parallel (step S5).

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

[0033] Next, the voltage correction means 152 corrects the voltage 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 parallel (connected in series) (No in step S5), the voltage 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 voltage detection value of each power conversion device 11 relative to the total voltage detection value by utilizing the state in which multiple power conversion devices 11 are connected in parallel. This makes it possible to correct each of the voltage detection values ​​of the multiple power conversion devices 11, thereby reducing detection errors in the output voltage.

[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 Voltage detection means 12 Power supply 13 Switching Method 14 Total voltage detection means 15 Control device 151 Voltage correction value calculation means 152 Voltage 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 parallel, a correction value for the voltage detection value of each power electronics device is calculated with respect to a total voltage detection value of each power electronics device; correcting the voltage detection value of each power conversion device using the correction value; power supply.

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