TWI818409B - power supply unit - Google Patents

Abstract

The present invention is a power supply device including: high-potential side and low-potential side wiring, which connects a plurality of batteries in parallel; a plurality of switching means, which individually switches the interruption of the wiring to the plurality of batteries; and control. The means is to control the aforementioned plurality of switching means; wherein the aforementioned control means is to perform connection switching control for sequentially switching one of the plurality of batteries connected to the aforementioned wiring within a unit time.

Description

power supply unit

The present invention relates to a power supply device.

It is proposed to have a power supply device that can connect multiple battery packs in parallel. On the other hand, when a plurality of battery packs with large voltage differences are connected in parallel, unexpected phenomena such as current flowing between the battery packs may occur. Patent Document 1 discloses a device that uses the power of either battery pack when the voltage difference between two battery packs is large. [Prior technical literature] [Patent Document]

[Patent Document 1] Specification of Chinese Public Patent No. 110682828A

[Problem to be solved by the invention]

In the device of Patent Document 1, the power consumption of a specific battery pack may increase, resulting in deterioration, or the frequency of charging or replacement may increase.

An object of the present invention is to provide a power supply device that efficiently uses multiple batteries. [Means to solve the problem]

According to the present invention, a power supply device is provided, which is provided with: The wiring on the high potential side and the low potential side connects multiple batteries in parallel; A plurality of switching means that individually switch the interruption of the plurality of batteries in the aforementioned wiring; and The control means is to control the plurality of switching means mentioned above; among which, The aforementioned control means are Within unit time, connection switching control is executed to sequentially switch one of the batteries connected to the wiring among the plurality of batteries. [Effects of the invention]

According to the present invention, it is possible to provide a power supply device that efficiently uses a plurality of batteries with easy control.

Hereinafter, embodiments will be described in detail with reference to the drawings. Furthermore, the following embodiments do not limit the invention related to the scope of the claimed invention, nor are they limited to the case where all combinations of features described in the embodiments are essential for the invention. Two or more of the plural features described in the embodiments may be combined arbitrarily. In addition, the same reference numerals are assigned to the same or identical components, and repeated descriptions are omitted.

FIG. 1 is a block diagram of a power supply device 1 according to an embodiment of the present invention. The power supply device 1 is a device that uses a DC power supply, that is, a plurality of batteries 2A and 2B (referred to as batteries 2 when collectively referred to or when there is no distinction) as a power source, and supplies power to a load. In the case of this embodiment, the load is the motor 3 and the power supply device 1 also functions as a drive device for driving the motor 3. For example, it can be used as a drive device for a motor that drives a vehicle. However, the present invention can be applied to a power supply device that supplies power to various loads, and can also be used in a fixed power supply, a mobile power supply, and the like.

In this embodiment, each battery 2 is a detachable battery, in particular, a mobile battery pack that can be detachable from the power supply device 1 . However, each battery 2 may be fixed to the power supply device 1 , and some of the batteries may be mobile battery packs, and the remaining batteries may be fixed to the power supply device 1 .

Each battery 2 includes a power storage unit 2a and a BMU (management system) 2b that manages the power storage unit 2a. The power storage unit 2a stores electric power output from the battery 2, and is configured by, for example, connecting a plurality of battery cells in series. The battery cells are, for example, lithium-ion battery cells.

The BMU 2b includes a processor that controls charging and discharging of the power storage unit 2a, a memory device such as a semiconductor memory that stores a program executed by the processor or information on the state of the power storage unit 2a, an input/output interface, and a control circuit described below. 19 Communication interface for communication. Furthermore, the BMU 2b includes a detection circuit for detecting the remaining capacity of the power storage unit 2a, charge and discharge current, and charge and discharge voltage. The processor controls the upper limit of the discharge power and the charge amount of the battery 2 based on the detection results of the detection circuit. For example, when the discharge power of the battery 2 reaches the upper limit, the processor controls the discharge of the power storage unit 2a in order to maintain the discharge power of the battery 2 at the upper limit.

In this embodiment, the motor 3 is an AC motor, for example, a three-phase brushless motor. The power supply device 1 converts the DC voltage output from the battery 2 into an AC voltage to drive the motor 3 .

The power supply device 1 includes terminals 10a, 10b, and 10c electrically connected to the battery 2A, and terminals 11a, 11b, and 11c electrically connected to the battery 2B. The positive terminal of the battery 2 is connected to the terminals 10a and 11a, and the negative terminal of the battery 2 is connected to the terminals 10b and 11b. The communication terminals of the BMU 2 b of the battery 2 are connected to the terminals 10 c and 11 c.

The power supply device 1 includes a high potential side DC wiring 12 and a low potential side DC wiring 13 . The potential difference (voltage) between the DC wiring 12 and the DC wiring 13 is called the output voltage Vout. The power supply device 1 further includes a plurality of switching elements SW1 and SW2. The DC wiring 12 is connected to the terminal 10a through the switching element SW1, and is connected to the terminal 11a through the switching element SW2. The DC wiring 13 is connected to the terminals 10b and 11b. With this configuration, the plurality of batteries 2A and 2B are connected in parallel to the DC wiring lines 12 and 13 .

The switching elements SW1 and SW2 are, for example, transistors, and individually switch on and off the plurality of batteries 2A and 2B of the DC wirings 12 and 13 according to the control signal from the control circuit 19 . In the case of this embodiment, the switching element SW1 connects the positive terminal of the battery 2A and the DC wiring 12 by being turned on, and disconnects the positive terminal of the battery 2A and the DC wiring 12 by turning it off. The switching element SW2 connects the positive terminal of the battery 2B and the DC wiring 12 by being turned on, and disconnects the positive terminal of the battery 2B and the DC wiring 12 by being turned off.

A diode 15 is provided between the DC wiring 12 and the DC wiring 13 to limit the flow of current from the DC wiring 13 to the DC wiring 12 . Furthermore, the power supply device 1 includes a smoothing circuit 14 that smoothes the output voltage Vout of the DC wirings 12 and 13 . In this embodiment, the smoothing circuit 14 is an LC filter circuit and includes an inductor 14 a connected in series with the DC wiring 12 and a capacitor 14 b connected between the DC wiring 12 and the DC wiring 13 .

The power supply device 1 includes an inverter 17 . The inverter 17 receives the output voltage Vout. The inverter 17 converts the DC voltage, that is, the output voltage Vout, into an AC voltage, and then outputs the voltage to the motor 3 from the three-phase terminal 18 . The inverter 17 includes, for example, an H-bridge circuit having four FETs (field effect transistors) and a control circuit that sequentially switches on and off each FET to convert the output voltage Vout into a single-phase AC voltage. The voltage detection circuit 16 detects the output voltage Vout input to the inverter 17 .

The power supply device 1 includes a control circuit 19 . The control circuit 19 includes, for example, a processor, a memory device such as a semiconductor memory, an input/output interface, a communication interface, etc. The memory device stores programs executed by the processor or data processed by the processor.

The control circuit 19 is connected through the terminals 10c and 11c to be able to communicate with the BMU 2b of each battery 2, and to obtain output capability information from the BMU 2b. The so-called output capability information is the status information related to the current output power of the battery 2, such as remaining capacity information (SOC: remaining power/full charge capacity × 100), voltage information (each output voltage V1, V2), etc. information.

Furthermore, the control circuit 19 may also be connected to communicate with the control circuit of the inverter 17 . Furthermore, the control circuit 19 is connected to the voltage detection circuit 16 and can obtain the detection result from the voltage detection circuit 16 .

＜Battery connection control＞ The control circuit 19 switches the connection form of the batteries 2A and 2B to the DC wirings 12 and 13 by controlling the on and off of the switching elements SW1 and SW2. In a state where both batteries 2A and 2B are connected to DC wiring 12 and 13, the electric power that can be supplied to the inverter 17 is maximum. However, when the difference between the output voltages of batteries 2A and 2B is large, current flows from one battery to the other battery. In the present embodiment, since the batteries 2A and 2B are interchangeable mobile battery packs, the difference in output voltage between the batteries 2A and 2B is likely to be large. In such a case, it is also possible to consider the case where only one of the batteries is continuously connected to the DC wiring 12 and 13. However, the power consumption of the battery will increase, resulting in deterioration, or the frequency of charging or replacement will change. high situation.

In this embodiment, a plurality of batteries 2A and 2B are efficiently used by controlling circuit 19 to perform connection switching control for alternately connecting batteries 2A and 2B to DC wirings 12 and 13 . Figure 2 is an explanatory diagram. In Figure 2, t represents the passage of time, and T represents unit time. In the connection switching control, the unit time T is regarded as one cycle, and within the unit time T, the battery connected to one of the DC wirings 12 and 13 among the batteries 2A and 2B is repeatedly and sequentially switched. The unit time T is, for example, a time in the range of 50 μs to 1 ms. V1 represents the output voltage of battery 2A, and V2 represents the output voltage of battery 2B. In the example shown in the figure, the relationship is V1>V2.

The output voltage Vout becomes the output voltage V1 when the switching element SW1 is on and the switching element SW2 is off, and becomes the output voltage V2 when the switching element SW2 is on and the switching element SW1 is off. Then, the output voltage Vout becomes the voltage V averaged over the unit time T.

In the example of FIG. 2 , in unit time T, the ON time of switching element SW1 (connection time of battery 2A) and the ON time of switching element SW2 (connection time of battery 2B) are respectively T/2. If the ratio of the on and off times in the unit time T is expressed as an duty ratio, the duty ratio of the switching element SW1 is 50%, and the duty ratio of the switching element SW2 is 50%. The average voltage V of the output voltage Vout=1/2×(V1+V2). The temporal waveform of the output voltage Vout becomes a signal that alternately repeats V1 and V2. Even when the difference between V1 and V2 is large, since the smoothing circuit 14 is provided in this embodiment, the output voltage Vout is smoothed through the smoothing circuit 14 and is input to the inverter 17 .

Assuming that V1=60V, V2=40V, and the current consumption is 100A, the output voltage of the inverter 17 is V=50V and the output power W=5kw. In this case, the average electric power output from battery 2A is 3 kW, and the average electric power output from battery 2B is 2 kW.

The control circuit 19 can change the connection time of each battery 2A and 2B to the DC wiring 12 and 13, that is, it can change the duty ratio. Figure 3 shows an example in which the duty ratio is changed. In the example shown in the figure, the duty ratio of the switching element SW1 is 20%, and the duty ratio of the switching element SW2 is 80%. The average voltage V of the output voltage Vout=1/5×V1+4/5×V2.

Figure 4 shows that when V1>V2, the working ratio of the switching element SW1 is compared with the relationship between the power ratio of the battery 2A and the battery 2B (chart G1), the relationship between the output voltage (chart G2), and the relationship between the power ratio of the battery 2A and the battery 2B. The relationship between the output power W1-max of the battery 2A (chart G3) is compared with the relationship between the output power W2-max of the battery 2B (chart G4), and the relationship between the output power of the inverter 17 (chart G5 ).

The duty ratio in FIG. 4 represents the duty ratio of the switching element SW1. Therefore, when the duty ratio is 0%, the duty ratio of the switching element SW2 is 100%. On the contrary, when the duty ratio is 100%, the duty ratio of the switching element SW2 is 0%. The horizontal axes of graphs G1 to G5 all represent the duty ratio of switching element SW1.

In the graph G1, if both the batteries 2A and 2B are connected to the DC wirings 12 and 13 and the current consumption is tentatively the same, the ratio of the electric power output from the battery 2A and the battery 2B becomes 50%. As shown in the graph G1, the ratio is 50% is still lower than the job ratio at the time.

In graph G2, when the duty ratio is 0%, the output voltage (Vout) is the output voltage V2 of battery 2B, and when the duty ratio is 100%, the output voltage (Vout) is the output voltage V1 (G2) of battery 2A. . The output voltage changes due to the duty ratio.

Graph G3 shows the output power W1-max of only the battery 2A in unit time T. As the duty ratio increases from 0%, the output power W1-max increases. When the power ratio is an duty ratio of 50%, the upper limit of the discharge power of the battery 2A (for example, the upper limit of the discharge current) is reached, and the output is limited by the BMU 2b of the battery 2A. After that, even if the duty ratio increases, the power can be output W1-max does not increase either.

Graph G4 shows the output power W2-max of only battery 2B in unit time T. Looking at the direction in which the duty ratio decreases from 100%, the duty ratio of the switching element SW2 increases from 0%, so the output power W2-max increases. When the power ratio is an duty ratio of 50%, the upper limit of the discharge power of battery 2B (for example, the upper limit of discharge current) is reached, and the output is limited by BMU 2b of battery 2B. After that, even if the duty ratio decreases (switching element SW2 (the working ratio increases), the output power W2-max does not increase.

Graph G5 shows the output power W-max of the inverter 17 in unit time T, which is the total value of the output power W1-max and W2-max of the batteries 2A and 2B. The output power W-max is the maximum at the duty ratio of 50%, and the output power W-max tends to decrease when the duty ratio increases or decreases. By controlling the duty ratio and limiting the discharge power of the battery 2 caused by the BMU 2b, the battery 2 can be protected and the output voltage Vout and the output power W-max can be controlled.

＜Processing example＞ An example of processing executed by the processor of the control circuit 19 will be described. FIG. 5 is a flowchart showing a processing example of a control mode for selecting switching elements SW1 and SW2. The processor of the control circuit 19 periodically executes the processing of the same figure. In S1, the voltage information of batteries 2A and 2B (respective output voltages V1 and V2) is obtained from each BMU2b of batteries 2A and 2B through communication. In S2, the voltage difference between the output voltages (V1, V2) obtained in S1 is calculated. In S3, it is determined whether the voltage difference (=|V1-V2|) calculated in S2 exceeds the threshold. The threshold value is, for example, a value in the range of 1.5 V, or a value of 1% to 3% of the average value of each output voltage (V1, V2).

If the voltage difference calculated in S2 exceeds the threshold, the process proceeds to S4, and if it does not, the process proceeds to S5. In S4, the above-mentioned connection switching control is executed, and batteries 2A and 2B are alternately connected to DC wirings 12 and 13. In S5, simultaneous connection control is performed to connect the batteries 2A and 2B to the DC wiring lines 12 and 13 together.

Under the simultaneous connection control of S5, the switching elements SW1 and SW2 are controlled to be turned on together. It can supply more power to the motor 3 of the load than the connection switching control. Under the connection switching control of S4, it is possible to prevent current from flowing between the battery 2A and the battery 2B, and these batteries 2 can be used efficiently.

FIG. 6 is a flowchart showing an example of drive control of the switching elements SW1 and SW2 that is executed when the connection switching control of S4 is selected, and is periodically executed in a shorter period than the process of FIG. 5 . In S11, the detection result of the output voltage Vout is obtained from the voltage detection circuit 16. In S12, the difference between the output voltage Vout obtained in S11 and the target output voltage is calculated. In S13, the voltage information of batteries 2A and 2B (respective output voltages V1 and V2) is obtained from each BMU2b of batteries 2A and 2B through communication. In S14, based on the difference calculated in S12 and the voltage information obtained in S13, the duty ratio of each switching element SW1 and SW2 is set in order to reduce the difference calculated in S12. The duty ratio is set in the range of 0%<duty ratio<100%. In S15, switching of the switching elements SW1 and SW2 is performed with the duty ratio set in S14. Through the above processing, the output voltage Vout can be maintained at the target output voltage.

＜Other embodiments＞ In the above embodiment, the switching elements SW1 and SW2 are provided on the DC wiring 12 on the high potential side. However, they may be provided on the DC wiring 13 on the low potential side. Figure 7 shows one example. In the example shown in the figure, both switching elements SW1 and SW2 are provided on the DC wiring 13 . Furthermore, it is also possible to adopt a configuration in which a part of the switching elements are provided on the DC wiring 12 and the remaining switching elements are provided on the DC wiring 13 .

Next, in the above embodiment, the control mode (S1~S3) of the switching elements SW1 and SW2 is selected based on the voltage information obtained from the BMU2b. However, the control mode may also be selected based on output capability information other than the voltage information. For example, when the SOC difference between battery 2A and battery 2B exceeds a certain value, connection switching control may be performed, and when the difference in SOC between battery 2A and battery 2B exceeds a certain value, simultaneous connection control may be performed.

Next, in the above embodiment, two batteries 2 are used. However, three or more batteries 2 may be used. FIG. 8 is a block diagram showing a power supply device 1A capable of connecting four batteries 2A to 2D. The structure of the power supply device 1A is the same as that of FIG. 1 . Switching elements SW1 to SW4 are provided corresponding to the batteries 2A to 2D, so that the batteries 2A to 2D and the DC wirings 12 and 13 can be switched on and off individually. FIG. 9 is an explanatory diagram of connection switching control in the configuration example of FIG. 8 . In the example shown in the figure, each duty ratio of the switching elements SW1 to SW4 is 25%.

Next, the power supply device 1 in FIG. 1 includes the inverter 17 and outputs AC power. However, the power supply device 1 may not include the inverter 17 and may directly supply the output voltage Vout to an external load.

Next, in the process of FIG. 5 , an example (S5) in which simultaneous connection control is selected when the voltage difference is equal to or less than the threshold value in S3 is explained. The condition for selecting simultaneous connection control is other than the condition that the voltage difference is equal to or less than the threshold value. Contains other conditions. As another condition, for example, the power required by the load exceeds a predetermined threshold. When other conditions are not met, connection switching control can be selected even if the voltage difference is below the threshold.

<Summary of Embodiments>

The above embodiment discloses at least the following power supply device.

1. The power supply device (1, 1A) of the above embodiment is provided with: high-potential side and low-potential side wiring (12, 13), which connect a plurality of batteries (2) in parallel; and a plurality of switching means (SW), which It is to individually switch the interruption of the aforementioned plurality of batteries in the aforementioned wiring; and the control means (19), which is to control the aforementioned plurality of switching means; wherein the aforementioned control means is to execute the aforementioned plurality of batteries within a unit time. Connection switching control (S4) for sequentially switching the batteries connected to one of the aforementioned wirings.

According to this embodiment, it is possible to provide a power supply device that efficiently uses a plurality of batteries with easy control.

2. In the above embodiment, in the connection switching control, the connection time of each battery in the wiring in the unit time (that is, the operation ratio of the battery) can be changed (S14).

According to this embodiment, the DC output voltage can be controlled.

3. The power supply device of the above embodiment is provided with: detection means (16) that detects the output voltage of the wiring; and the control means changes the voltage of the wiring according to the detection result of the detection means during the connection switching control. The connection time of each battery within the aforementioned unit time (S11, S14).

According to this embodiment, the DC output voltage can be controlled in accordance with the target voltage.

4. In the above embodiment, the control means determines whether to execute the connection switching control (S3) based on the output capability information of each battery.

According to this embodiment, when there is a difference in output capability between the batteries, the connection switching control is executed to utilize the batteries.

5. In the above embodiment, the control means executes the connection switching control (S3, S4) when the output voltage difference between the plurality of batteries exceeds a certain value.

According to this embodiment, the connection switching control is executed when there is a risk of current flowing between the batteries, thereby preventing the problem and utilizing the batteries.

6. In the above embodiment, the control means performs control of simultaneously connecting the plurality of batteries to the wiring (S3, S5) under the condition that the output voltage difference between the plurality of batteries is a certain value or less.

According to this embodiment, larger power can be supplied to the load.

7. The power supply device according to the above embodiment includes a smoothing circuit (component symbol 14 in FIG. 1 ) that smoothes the output voltage of the wiring.

According to this embodiment, even if the batteries connected to one of the wirings are sequentially switched, an averaged and stable voltage can be output.

8. In the above embodiment, the plurality of batteries are mobile battery packs equipped with a management system (2b); the control means can communicate with the management system.

According to this embodiment, information related to the status of the mobile battery pack can be obtained from the management system.

9. In the above embodiment, the management system controls the upper limit of the discharge power of the battery.

According to this embodiment, the aforementioned batteries can be protected, and a plurality of batteries can be used efficiently.

10. The power supply device of the above embodiment includes an inverter (17) that converts the output voltage (Vout) of the wiring into an AC voltage.

According to this embodiment, power can be provided to a load consuming AC power.

11. In the above embodiment, at least one of the plurality of batteries is a removable battery.

According to this embodiment, detachable batteries with different states of use or degradation can be effectively used.

The embodiments related to the invention have been described above. However, the invention is not limited to the above-described embodiments, and various modifications and changes are possible within the scope of the gist of the invention.

1: Power supply unit

2:Battery

3: Motor

12: DC wiring

13:DC wiring

14: Smoothing circuit

15: Diode

16: Voltage detection circuit

17:Inverter

18:Terminal

19:Control circuit

10a:Terminal

10b:Terminal

10c: terminal

11a:Terminal

11b:Terminal

11c:Terminal

14a:Inductor

14b:Capacitor 1A:Power supply unit 2A:Battery 2a: Power storage department 2b:BMU (management system) 2B:Battery 2C:Battery 2D:Battery SW1: switching element SW2: switching element SW3: switching element SW4: switching element Vout: output voltage

[Fig. 1] is a block diagram of a power supply device according to an embodiment of the present invention. [Fig. 2] is a timing flow chart showing the relationship between the turn-on and turn-off timing of each switching element and the output voltage. [Fig. 3] is a timing flow chart showing the relationship between the turn-on and turn-off timing of each switching element and the output voltage. [Figure 4] is a graph showing changes in the ratio of connection time, power ratio, output voltage, individual output power, and total output power. [Fig. 5] is a flowchart showing an example of processing executed by the control circuit. [Fig. 6] is a flowchart showing an example of processing executed by the control circuit. [Fig. 7] A block diagram showing a modification of the power supply device of Fig. 1. [Fig. [Fig. 8] is a block diagram showing another example of a power supply device with a different number of batteries. [FIG. 9] is a timing flow chart showing the turn-on and turn-off timing of each switching element in the example of FIG. 8.

1: Power supply unit

2A:Battery

2a: Power storage department

2b:BMU (management system)

2B:Battery

3: Motor

12: DC wiring

13:DC wiring

14: Smoothing circuit

15: Diode

16: Voltage detection circuit

17:Inverter

18:Terminal

19:Control circuit

10a:Terminal

10b:Terminal

10c: terminal

11a:Terminal

11b:Terminal

11c:Terminal

14a:Inductor

14b:Capacitor

SW1: switching element

SW2: switching element

Vout: output voltage

Claims (10)

A power supply device provided with: high-potential side and low-potential side wiring for connecting a plurality of batteries in parallel; a plurality of switching means for individually switching the interruption of the wiring to the plurality of batteries; and a control means, It is to control the aforementioned plurality of switching means; wherein, the aforementioned control means is to perform connection switching control to sequentially switch one of the aforementioned plurality of batteries connected to the aforementioned wiring within a unit time; the aforementioned control means is based on the aforementioned The output capability information of each battery is used to determine whether to execute the aforementioned connection switching control. The power supply device according to claim 1, wherein in the connection switching control, the connection time of each battery in the wiring within the unit time can be changed. The power supply device of claim 1, further comprising: a detection means that detects the output voltage of the wiring; and the control means, in the connection switching control, changes each condition of the wiring based on the detection result of the detection means. The connection time of the battery within the aforementioned unit time. The power supply device according to any one of claim 1 to claim 3, wherein the control means is configured to ensure that the output voltage difference between the plurality of batteries exceeds If the value exceeds the determined value, the aforementioned connection switching control is performed. The power supply device according to any one of claim 1 to claim 3, wherein the control means is executed to simultaneously connect the plurality of batteries to the wiring under the condition that the output voltage difference between the plurality of batteries is below a certain value. control. The power supply device of claim 1 further includes a smoothing circuit for smoothing the output voltage of the wiring. Such as the power supply device of claim 1, wherein the plurality of batteries are mobile battery packs equipped with a management system; the control means can communicate with the management system. The power supply device of claim 7, wherein the management system controls the upper limit of the discharge power of each of the plurality of batteries. The power supply device of Claim 1 further includes an inverter that converts the output voltage of the wiring into an AC voltage. The power supply device of claim 1, wherein at least one of the plurality of batteries is a removable battery.

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