Power supply device

Abstract

To provide a power supply device capable of equalizing output voltages of respective power conversion devices while following a required current.SOLUTION: The power supply device includes a plurality of power conversion devices connected in series and a control device, and the control device calculates a total voltage command value based on a total current command value and a total current detection value of each power conversion device, and calculates a power command value of each power conversion device based on the total voltage command value and a voltage detection value of each power conversion device.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 for controlling voltage in a power supply device having multiple power conversion devices connected in series, in which the average voltage per power conversion device is used as a command value and the deviation from the measured voltage is determined in order to equalize the output voltage of each power conversion device. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2018-098834 Summary of the Invention [Problem to be solved by the invention]

[0004] The technology disclosed in Patent Document 1 can equalize the output voltage of a voltage-controlled power conversion device, but does not have the function of following the required current, so 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 equalize the output voltages of the power conversion devices while following the required current. [Means for solving the problem]

[0006] The power supply device according to the present disclosure includes a plurality of power conversion devices connected in series and a control device, and the control device calculates a total voltage command value based on a total current command value and a total current detection value of each power conversion device, and calculates a power command value for each power conversion device based on the total voltage command value and the voltage detection value of each power conversion device. [Effects of the Invention]

[0007] According to the present disclosure, it is possible to equalize the output voltages of the power conversion devices and control the total output current while following the required current. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a circuit diagram showing a configuration of a power supply device according to an embodiment in which input sides are connected in parallel. [Figure 2] FIG. 2 is a circuit diagram showing the configuration of the power supply device according to the embodiment when the input sides are connected in series. [Figure 3] FIG. 3 is a diagram showing an example of the variation in output voltages of power conversion devices A and B in a conventional power supply device, in which a total power command value is calculated based on the total current command value and the total current detection value of each power conversion device, and the total power command value is divided by the number of power conversion devices to obtain an equal value, which is used as the power command value for each power conversion device. [Figure 4] FIG. 4 is a diagram showing a control block of the control device when the power conversion device is of a power control type in the power supply device according to the embodiment. [Figure 5] FIG. 5 is a diagram showing an example of the variation in the output voltages of power conversion devices A and B when, in a power supply device according to an embodiment, a total voltage command value is calculated based on a total current command value and a total current detection value of each power conversion device, and a power command value of each power conversion device is calculated based on the total voltage command value and the voltage detection value of each power conversion device. [Figure 6] FIG. 6 is a diagram showing a control block of the control device when the power conversion device is of a current control type in 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 where the input sides of the power supply device 1 are connected in parallel. Figure 2 shows a case where the input sides of the power supply device 1 are connected in series.

[0011] The power supply device 1 includes a plurality of power conversion devices 11, a power supply 12, total current detection means 13, total voltage detection means 14, and a control device 15. Although Figs. 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. In the following description, the two power conversion devices 11 shown in Figs. 1 and 2 may be referred to as "power conversion devices A and B." The power supply device 1 is connected to a load 2, such as a battery of an electric vehicle.

[0012] The input side and output side of the power conversion device 11 are electrically insulated. The output side of the power conversion device 11 is electrically connected in series. The power conversion device 11 also includes an isolated switching circuit 111, a smoothing capacitor 112, a voltage detection means 113, a current detection means 114, and an output power control means 115. The switching circuit 111 may be, for example, a full-bridge phase shift, a dual active bridge, or an LLC.

[0013] The voltage detection means 113 is a means for detecting the voltage output by each power conversion device 11. The current detection means 114 is a means for detecting the current output by each power conversion device 11. The total current detection means 13 is a means for detecting the total current output by the power supply device 1 (total output current). The total voltage detection means 14 is a means for detecting the total voltage output by the power supply device 1 (total output voltage).

[0014] 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] The control device 15 calculates a total voltage command value based on the total current command value and total current detection value of each power conversion device 11, and calculates a power command value for each power conversion device 11 based on the total voltage command value and the voltage detection value of each power conversion device 11.

[0016] That is, the control device 15 determines a total voltage command value from the deviation between the total current command value and the total current detection value. The control device 15 also determines a power command value for each power conversion device 11 from the deviation between the value obtained by dividing the total voltage command value by the number of power conversion devices 11 (number of series connections) and the voltage detection value of each power conversion device 11. In this way, the control device 15 controls the total output current of the power supply device 1 while equalizing the output voltages of the multiple power conversion devices 11.

[0017] In a conventional power supply, a total power command value is calculated based on the total current command value and total current detection value of each power conversion device, and the calculated total power command value is divided by the number of power conversion devices (e.g., two). This equalized value is used as the power command value for each power conversion device. In other words, the conventional power supply controls the power conversion devices by feeding back only the total current of each power conversion device. In this conventional power supply, as shown in Figure 3, the output voltages of two power conversion devices A and B vary significantly. Note that in Figure 3, "current error only" indicates a case where the voltage detection error of each power conversion device is zero and only a current detection error exists. Also, in Figure 3, "current + voltage error" indicates a case where both a voltage detection error and a current detection error exist in each power conversion device. It can be seen that the output voltages of the conventional power supply vary significantly in both the "current error only" case and the "current + voltage error" case.

[0018] Therefore, in the power supply device according to the embodiment, as shown in Fig. 4, a total voltage command value is calculated based on the total current command value and the total current detection value of each power conversion device 11. Then, the power command value of each power conversion device 11 is determined from the deviation between the value obtained by dividing this total voltage command value by the number of power conversion devices 11 (for example, two) and the voltage detection value of each power conversion device 11. That is, in the power supply device according to the embodiment, control is performed by feeding back the total current and total voltage of each power conversion device 11 (double feedback). As a result, in the power supply device according to the embodiment, it is possible to reduce the variation in the output voltages of two power conversion devices A and B, as shown in Fig. 5, for example.

[0019] In addition, in this case, if the detection error of the voltage detection means 113 provided in each power conversion device 11 is zero and a detection error exists only in the current detection means 114, it is theoretically possible to control the output voltage variation of the two power conversion devices A and B to zero.

[0020] In the above description, the multiple power conversion devices 11 are assumed to be of the power control type, but they may be of the current control type. In this case, an "output current control means" is provided instead of the output power control means 115 of the power conversion device 11.

[0021] Furthermore, when the multiple power conversion devices 11 are of the current control type, the control device 15 determines a total voltage command value from the deviation between a total current command value and a total current detection value, as shown in Fig. 6. The control device 15 also determines a current command value for each power conversion device 11 from the deviation between the value obtained by dividing the total voltage command value by the number of power conversion devices 11 (number of series connections) and the voltage detection value of each power conversion device 11. In this way, the control device 15 controls the total output current of the power supply device 1 while equalizing the output voltages of the multiple power conversion devices 11.

[0022] As described above, the power supply device according to the embodiment can be used as a charger compatible with high-voltage secondary batteries by connecting the output sides of multiple power conversion devices 11 in series. When the power supply device according to the embodiment is a charger for charging secondary batteries, and in particular for charging the main battery of an electric vehicle, the total current command value may be determined based on the required value of the total output current sent from the vehicle, as shown in Figs. 4 and 6.

[0023] Furthermore, if the secondary battery has a means for detecting the voltage across it and the control device 15 can acquire the detected voltage value of the secondary battery, the voltage of the secondary battery (vehicle voltage) may be used as a feedforward term in the control blocks of Figures 4 and 6. This can improve the ability to follow the command value.

[0024] In addition, when a required value for total output power is sent from the vehicle instead of a required value for total output current, a similar response can be achieved by dividing the required value for total output power by the total voltage detection value or the detected value of the battery voltage sent from the vehicle and setting the result as the total current command value.

[0025] In the power supply device according to the embodiment described above, dual feedback of current control and voltage control is performed in a configuration in which the output sides of power control type (or current control type) power conversion devices 11 are connected in series, and different command values ​​are given to each power conversion device 11. This makes it possible to equalize the output voltages of the power conversion devices 11 and control the total output current while following the required current.

[0026] 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]

[0027] 1 Power supply 11 Power conversion device 111 Switching Circuits 112 Smoothing capacitor 113 Voltage detection means 114 Current detection means 115 Output power control means 12 Power supply 13 Total current detection means 14 Total voltage detection means 15 Control device 2. Load

Claims

[Claim 1] a plurality of power conversion devices connected in series; a control device; Equipped with The control device Calculating a total voltage command value based on the total current command value and the total current detection value of each power conversion device; calculating a power command value for each power electronics device based on the total voltage command value and the voltage detection value of each power electronics device; power supply.

Images