Power supply device and method for controlling power supply device

Abstract

The invention provides a power supply device and a method for controlling the power supply device, which can heat a plurality of power supplies more efficiently than in the prior art without causing an increase in cost by energizing a high-frequency current. This power supply device is provided with a first power supply, a second power supply, a switching circuit having first to third switching elements, and a control device that controls a first reactor, a second reactor, and the switching circuit. A first state in which the first power supply is connected between the first node and the fourth node via the first reactor and the second power supply is connected to both ends of the second reactor is alternately switched; and a second state in which the second power supply is connected between the first node and the fourth node via the second reactor and the first power supply is connected to both ends of the first reactor.

Description

Technical Field

[0001] The present invention relates to a power supply device and a control method of the power supply device. Background Art

[0002] In recent years, toward the goal of a low-carbon society, there has been an increasing number of vehicles equipped with a traction motor as a power source, either in place of an engine or in addition to an engine. Patent Documents 1 and 2 below disclose battery control systems that increase the temperature of the battery that supplies power to the traction motor of such vehicles. For example, the battery control system disclosed in Patent Document 1 includes a first battery and a second battery, each having output characteristics that differ depending on temperature. When the temperature of the first battery falls below a predetermined temperature, the second battery is preferentially used to increase the temperature of the first battery.

[0003] Patent Document 1: Japanese Patent Application Laid-Open No. 2020-092509

[0004] Patent Document 2: Japanese Patent Application Laid-Open No. 2023-527451 Summary of the Invention

[0005] The battery control system disclosed in Patent Document 1 requires two batteries with different output characteristics depending on temperature, which increases costs. In the battery control system disclosed in Patent Document 1, the second battery is placed around the first battery, raising the temperature of the first battery. This does not effectively warm the batteries.

[0006] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a power supply device and a power supply device control method capable of heating a plurality of power supplies more efficiently than conventional ones by passing high-frequency current without incurring a cost increase.

[0007] In order to solve the above-mentioned problems and achieve the object, the present invention adopts the following means.

[0008] (1): A power supply device according to one embodiment of the present invention comprises a first power supply connected between a first node and a second node and a second power supply connected between a third node and a fourth node, for supplying electric power to an electric load connected between the first node and the fourth node, wherein the power supply device comprises: a switching circuit having a first switch connected between the first node and the third node, a second switch connected between the second node and the third node, and a third switch connected between the second node and the fourth node; a first inductor arranged between the first power supply and the first node or the second node; a second inductor arranged between the second power supply and the third node or the fourth node; and a control device, which switches The control device switches between a first state and a second state alternately, wherein the first state refers to a state in which the control device controls the second switch and the third switch of the switching circuit to a closed state, and controls the first switch to an open state, so that the first power supply is connected between the first node and the fourth node via the first inductor, and the second power supply is connected to both ends of the second inductor; the second state refers to a state in which the control device controls the first switch and the second switch of the switching circuit to a closed state, and controls the third switch to an open state, so that the second power supply is connected between the first node and the fourth node via the second inductor, and the first power supply is connected to both ends of the first inductor.

[0009] (2): Based on the scheme of (1) above, the control device may temporarily set the state to a third state when switching between the first state and the second state. The third state refers to a state in which the control device controls the first switch and the third switch to an open state and controls the second switch to a closed state, so that the first power supply is connected between the first node and the fourth node via the first inductor, and the second power supply is connected between the first node and the fourth node via the second inductor.

[0010] (3): Based on the above-mentioned scheme (1) or (2), the power supply device may also include a voltage detection unit for detecting the voltages of the first power supply and the second power supply, and the control device may implement a balance control by alternating first control and second control when the voltage of the first power supply is greater than the voltage of the second power supply, wherein the first control is a control for setting the first switch to a closed state and the second switch and the third switch to an open state, and the second control is a control for setting the first switch, the second switch, and the third switch to an open state.

[0011] (4): Based on the above-mentioned scheme (1) or (2), the power supply device may also include a voltage detection unit for detecting the voltages of the first power supply and the second power supply, and the control device may implement a balance control by alternating between a third control and a second control when the voltage of the second power supply is greater than the voltage of the first power supply, wherein the third control is a control for setting the first switch and the second switch to an open state and setting the third switch to a closed state, and the second control is a control for setting the first switch, the second switch, and the third switch to an open state.

[0012] (5): Based on the above-mentioned scheme (3) or (4), the control device may also be capable of switching between a parallel state and a series state, wherein the parallel state refers to a state in which the control device controls the first switch and the third switch to a closed state and controls the second switch to an open state, thereby the first power supply and the second power supply are connected in parallel between the first node and the fourth node; and the series state refers to a state in which the control device controls the first switch and the third switch to an open state and controls the second switch to a closed state, thereby the first power supply and the second power supply are connected in series between the first node and the fourth node. When the difference between the voltage of the first power supply and the voltage of the second power supply detected by the voltage detection unit is greater than a predetermined reference value and a transition to the parallel state is indicated, the balancing control is implemented.

[0013] (6) In a control method for a power supply device according to one embodiment of the present invention, the power supply device includes a first power supply connected between a first node and a second node and a second power supply connected between a third node and a fourth node, and supplies power to an electric load connected between the first node and the fourth node, wherein the power supply device includes: a switching circuit having a first switch connected between the first node and the third node, a second switch connected between the second node and the third node, and a third switch connected between the second node and the fourth node; a first inductor arranged between the first power supply and the first node or the second node; and a second inductor arranged between the second power supply and the third node or the fourth node, wherein The control method of the power supply device has the following steps: alternately switching between a first state and a second state, wherein the first state refers to controlling the second switch and the third switch of the switching circuit to a closed state, and controlling the first switch to an open state, so that the first power supply is connected between the first node and the fourth node via the first inductor, and the second power supply is connected to both ends of the second inductor; and the second state refers to controlling the first switch and the second switch of the switching circuit to a closed state, and controlling the third switch to an open state, so that the second power supply is connected between the first node and the fourth node via the second inductor, and the first power supply is connected to both ends of the first inductor.

[0014] According to the schemes (1) and (6), the open and closed states of the plurality of switches provided in the switching circuit are controlled to alternately switch between the first state and the second state. This allows high-frequency current to flow through the first power supply and the second power supply, thereby allowing the first power supply and the second power supply to be heated more efficiently than before without incurring an increase in cost.

[0015] According to the solution (2), when switching between the first state and the second state, the first switch and the third switch are temporarily opened and the second switch is closed, thereby preventing the first switch and the third switch from being closed at the same time.

[0016] According to the aspects (3) and (4), balance control is performed based on the magnitude relationship between the voltage of the first power supply and the voltage of the second power supply detected by the voltage detection unit, so that the voltage of the first power supply and the voltage of the second power supply can be made equal.

[0017] According to the scheme (5), when the difference between the voltage of the first power supply detected by the voltage detection unit and the voltage of the second power supply is greater than a predetermined reference value and a transition to the parallel state is instructed, balancing control is performed, thereby suppressing the short-circuit current when transitioning to the parallel state. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a circuit diagram showing a main configuration of a power supply device according to one embodiment of the present invention.

[0019] Figure 2 This is a diagram showing a current path when the power supply device according to one embodiment of the present invention operates in the series mode or the parallel mode.

[0020] Figure 3 This is a diagram showing a current path when the power supply device according to one embodiment of the present invention operates in a warming mode.

[0021] Figure 4 This is a diagram showing current changes when the power supply device according to one embodiment of the present invention operates in the warming mode.

[0022] Figure 5 This is a diagram showing the relationship between the amplitude and the ratio (T / Tf) of the current flowing when the power supply device according to one embodiment of the present invention operates in the heating mode.

[0023] Figure 6 This is a diagram showing a current path when the power supply device according to one embodiment of the present invention operates in the first voltage balance mode.

[0024] Figure 7 This is a diagram showing current changes when the power supply device according to one embodiment of the present invention operates in the first voltage balance mode.

[0025] Figure 8 This is a diagram showing a current path when the power supply device according to one embodiment of the present invention operates in the second voltage balance mode.

[0026] Figure 9 This is a diagram showing current changes when the power supply device according to one embodiment of the present invention operates in the second voltage balance mode.

[0027] Figure 10 This is a flowchart showing processing when voltage balance control is performed in the power supply device according to one embodiment of the present invention. DETAILED DESCRIPTION

[0028] Hereinafter, embodiments of a power supply device and a method for controlling a power supply device according to the present invention will be described with reference to the accompanying drawings.

[0029] Power supply unit

[0030] Figure 1 1 is a circuit diagram showing the main structure of a power supply device according to an embodiment of the present invention. Figure 1As shown, the power supply device 1 of this embodiment includes a first power supply 11, a second power supply 12, a switching circuit 13, a first reactor 14, a second reactor 15, a capacitor 16, a voltage detection unit 17, a voltage detection unit 18, and a control device 19. Such a power supply device 1 supplies DC power to an electrical load connected via a contactor 20, for example.

[0031] Examples of electrical loads supplied with DC power from the power supply device 1 include an inverter 21 that controls the traction and regeneration of the electric motor M that generates the vehicle's driving force, an auxiliary machine 22 and an auxiliary machine VCU (Voltage Control Unit) 23 installed in the vehicle, and an inlet 24 installed in the vehicle. It should be noted that a three-phase brushless DC motor, for example, can be used as the electric motor M. The auxiliary machine VCU 23 controls the voltage applied to the auxiliary machine 22.

[0032] The first power supply 11 is a rechargeable secondary battery (e.g., a storage battery). The positive terminal of the first power supply 11 is connected to a first node N1, and the negative terminal is connected to a second node N2. The second power supply 12 is a rechargeable secondary battery (e.g., a storage battery). The positive terminal of the second power supply 12 is connected to a third node N3, and the negative terminal is connected to a fourth node N4. The first power supply 11 and the second power supply 12 are the same power source, and the voltage Vs1 of the first power supply 11 and the voltage Vs2 of the second power supply 12 are equal (or approximately equal). It should be noted that the voltage Vs1 of the first power supply 11 and the voltage Vs2 of the second power supply 12 are voltages suitable for operating the auxiliary machine 22 (e.g., 400 V).

[0033] Note that one end of the above-mentioned electric loads (the inverter 21 , the auxiliary unit VCU 23 , and the inlet 24 ) is connected to the first node N1 via the contactor 20 , and the other end is connected to the fourth node N4 via the contactor 20 .

[0034] The switching circuit 13 includes three switching elements (first switching element SW1 to third switching element SW3 (first switch to third switch)) connected in series. Under the control of the control device 19, the switching circuit 13 switches the connection between the first power supply 11, the second power supply 12, and the electrical load. The first switching element SW1 is connected between the first node N1 and the third node N3, the second switching element SW2 is connected between the second node N2 and the third node N3, and the third switching element SW3 is connected between the second node N2 and the fourth node N4.

[0035] Here, as the first to third switching elements SW1 to SW3, for example, MOSFETs (Metal-Oxide-Semiconductor Field-Effect Transistors) can be used. The specific connection relationship when using MOSFETs as the first to third switching elements SW1 to SW3 is as follows. The drain of the first switching element SW1 is connected to the first node N1, and the source is connected to the third node N3. The drain of the second switching element SW2 is connected to the third node N3, and the source is connected to the second node N2. The drain of the third switching element SW3 is connected to the second node N2, and the source is connected to the fourth node N4. It should be noted that a diode is connected between the source and drain of each of the first to third switching elements SW1 to SW3, with the direction of flow from the source to the drain being forward.

[0036] Switching circuit 13 is controlled by, for example, a pulse width modulated (PWM) signal (PWM signal) output from control device 19 and input to the gates of first through third switching elements SW1 through SW3. A specific switching control method for switching circuit 13 will be described later.

[0037] The first reactor 14 is disposed between the first power supply 11 and the second node N2. More specifically, one end of the first reactor 14 is connected to the negative terminal of the first power supply 11, and the other end is connected to the connection point between the source of the second switching element SW2 and the drain of the third switching element SW3. The second reactor 15 is disposed between the second power supply 12 and the third node N3. More specifically, one end of the second reactor 15 is connected to the positive terminal of the second power supply 12, and the other end is connected to the connection point between the source of the first switching element SW1 and the drain of the second switching element SW2.

[0038] Capacitor 16 is connected between first node N1 and fourth node N4. Specifically, one electrode of capacitor 16 is connected to first node N1, and the other electrode is connected to fourth node N4. Capacitor 16 is provided to smooth the current output from power supply device 1. Voltage detection unit 17 detects voltage Vs1 of first power supply 11 and outputs the detection result to control device 19. Voltage detection unit 18 detects voltage Vs2 of second power supply 12 and outputs the detection result to control device 19.

[0039] The control device 19 includes, for example, a first control unit 19a and a second control unit 19b, and performs switching control of the switching circuit 13 and control of the electrical load (for example, drive control of the inverter 21). The first control unit 19a performs switching control of the switching circuit 13 to switch the connection state between the first power supply 11, the second power supply 12, and the electrical load.

[0040] The power supply device 1 of this embodiment has a parallel mode and a series mode as operating modes. The parallel mode operates when the first power supply 11 and the second power supply 12 are connected in parallel with the electrical load (parallel state). The series mode operates when the first power supply 11 and the second power supply 12 are connected in series with the electrical load (series state). The first control unit 19a controls the switching circuit 13 to switch between the parallel mode and the series mode.

[0041] As the above-mentioned operation modes, in addition to the above-mentioned parallel mode and series mode, there are also a heating mode and a voltage balance mode. The heating mode is an operation mode that uses a chopping method to heat the first power supply 11 and the second power supply 12. The voltage balance mode is an operation mode that makes the voltage of the first power supply 11 equal to the voltage of the second power supply 12. If the voltage of the first power supply 11 is different from the voltage of the second power supply 12, a short-circuit current flows from one of the first power supply 11 and the second power supply 12 to the other. In order to prevent this situation, the voltage balance mode is implemented. It should be noted that the details of the operation mode and operation state of the power supply device 1 are described later.

[0042] The second control unit 19b controls the electrical loads supplied with DC power from the power supply device 1. For example, during power traction operation of the motor M, the second control unit 19b converts the DC power applied between the positive and negative terminals on the DC side of the inverter 21 into three-phase AC power, and sequentially commutates the current flowing through each phase of the motor M, thereby flowing AC current through each phase. Furthermore, during regenerative operation of the motor M, for example, the second control unit 19b converts the AC generated power output from the motor M into DC power while synchronizing the power based on the rotation angle of the motor M.

[0043] 〈Series Mode and Parallel Mode〉

[0044] Figure 2 This is a diagram showing the current path when the power supply device according to one embodiment of the present invention operates in series mode or parallel mode. Figure 2 In the figure, the voltage detection units 17 and 18, the control device 19, and the electric load are omitted. Figure 2 (a) is a diagram showing the current path when operating in series mode. Figure 2(b) is a diagram showing a current path when operating in the parallel mode.

[0045] like Figure 2 As shown in (a) of FIG. 1 , in the series mode, the first control unit 19a of the control device 19 sets the second switch element SW2 to a closed state (ON) and sets the first switch element SW1 and the third switch element SW3 to an open state (OFF). Figure 2 As shown in (a), a current loop LP1 is formed that passes through the fourth node N4, the second power supply 12, the second inductor 15, the second switching element SW2, the first inductor 14, the first power supply 11, and the first node N1 in sequence. That is, in the series mode, the first power supply 11 and the second power supply 12 are connected in series between the first node N1 and the fourth node N4. It should be noted that during regeneration, the current flowing in the series mode is connected to the first node N1. Figure 2 The direction of the current in the current loop LP1 shown in (a) is opposite to the direction of the current.

[0046] like Figure 2 As shown in (b) of FIG. 1 , in the parallel mode, the first control unit 19a of the control device 19 sets the first switching element SW1 and the third switching element SW3 to the closed state (ON), and sets the second switching element SW2 to the open state (OFF). Figure 2 As shown in (b), a current loop LP2 is formed, which passes through the fourth node N4, the third switching element SW3, the first inductor 14, the first power supply 11, and the first node N1 in sequence, and a current loop LP3 is formed, which passes through the fourth node N4, the second power supply 12, the second inductor 15, the first switching element SW1, and the first node N1 in sequence. That is, in the parallel mode, the first power supply 11 and the second power supply 12 are connected in parallel between the first node N1 and the fourth node N4. It should be noted that during regeneration, the current flowing in parallel with Figure 2 In the current loop shown in (b), the currents of LP2 and LP3 are in opposite directions.

[0047] <Heating mode>

[0048] Figure 3 FIG. 1 is a diagram showing a current path when the power supply device according to one embodiment of the present invention operates in a heating mode. Figure 3 In, with Figure 2 Similarly, the voltage detection units 17 and 18, the control device 19, and the electrical load are omitted. In the heating mode, the first control unit 19a of the control device 19 controls the switch circuit 13 to alternately switch Figure 3 The first state shown in (a) is Figure 3It should be noted that the switching frequency between the first state and the second state is, for example, several tens to several hundreds of kHz.

[0049] Here, the first control unit 19a Figure 3 The first state shown in (a) is Figure 3 In the case of the second state switching shown in (b), temporarily set Figure 3 After the third state shown in (c), it switches to Figure 3 The first control unit 19a is in the second state shown in (b). Figure 3 The second state shown in (b) Figure 3 When the first state shown in (a) is switched, it is temporarily set to Figure 3 After the third state shown in (c), it switches to Figure 3 The first state shown in (a).

[0050] Here, the first state described above is a state in which the first power supply 11 is connected between the first node N1 and the fourth node N4 via the first inductor 14, and the second power supply 12 is connected to both ends of the second inductor 15. The second state described above is a state in which the second power supply 12 is connected between the first node N1 and the fourth node N4 via the second inductor 15, and the first power supply 11 is connected to both ends of the first inductor 14. The third state described above is a state in which the first power supply 11 is connected between the first node N1 and the fourth node N4 via the first inductor 14, and the second power supply 12 is connected between the first node N1 and the fourth node N4 via the second inductor 15.

[0051] It should be noted that according to Figure 3 (a)~ Figure 3 As can be seen from (c), in the heating mode, at least one of the first power source 11 and the second power source 12 is connected between the first node N1 and the second node N2.

[0052] like Figure 3As shown in (a) of FIG1 , the first control unit 19a sets the first switching element SW1 to the open state (off) and the second and third switching elements SW2 and SW3 to the closed state (on), thereby achieving the aforementioned first state. In the first state, a current loop LP11 is formed, which sequentially passes through the third switching element SW3, the first reactor 14, the first power supply 11, and the capacitor 16. A current loop LP12 is also formed, which sequentially passes through the second power supply 12, the second reactor 15, the second switching element SW2, and the third switching element SW3. Current loop LP11 is the current path when the first power supply 11 is connected between the first node N1 and the fourth node N4 via the first reactor 14. Current loop LP12 is the current path when the second power supply 12 is connected to both ends of the second reactor 15.

[0053] like Figure 3 As shown in (b) of FIG1 , the first control unit 19a sets the first and second switching elements SW1 and SW2 to the closed state (ON) and the third switching element SW3 to the open state (OFF), thereby achieving the aforementioned second state. In the second state, a current loop LP13 is formed, which sequentially passes through the first power supply 11, the first switching element SW1, the second switching element SW2, and the first reactor 14. A current loop LP14 is also formed, which sequentially passes through the second power supply 12, the second reactor 15, the first switching element SW1, and the capacitor 16. Current loop LP13 is the current path when the first power supply 11 is connected to both ends of the first reactor 14. Current loop LP14 is the current path when the second power supply 12 is connected between the first node N1 and the fourth node N4 via the second reactor 15.

[0054] like Figure 3 As shown in (c), the first control unit 19a sets the first switch element SW1 and the third switch element SW3 to the open state (off) and the second switch element SW2 to the closed state (on), thereby setting the third state. Figure 3 (a) shows the current loop LP11 and Figure 3 That is, in the third state, the first power supply 11 and the second power supply 12 are connected in parallel between the first node N1 and the fourth node N4.

[0055] Figure 4 1 is a diagram showing the current change when the power supply device according to one embodiment of the present invention operates in the heating mode. Figure 4 In the Figure 3 The period of the first state shown in (a) is set as period Ta1, and Figure 3The period of the second state shown in (b) is set as period Tb1. Figure 3 The first state shown in (a) is Figure 3 In the case of the second state switching shown in (b), it is temporarily set to Figure 3 The period of the third state shown in (c) is set as period Ta2. Figure 3 The second state shown in (b) Figure 3 When the first state shown in (a) is switched, it is temporarily set to Figure 3 The period of the third state shown in (c) is referred to as period Tb2.

[0056] like Figure 4 As shown, the first control unit 19a controls the first switching element SW1 to the third switching element SW3 of the switching circuit 13 to perform Figure 3 (a)~ Figure 3 Specifically, the switching of each state shown in (c) is performed. Figure 3 The first state (period Ta1) shown in (a) Figure 3 The third state (period Ta2) shown in (c) Figure 3 The second state (period Tb1) shown in (b) Figure 3 The third state (period Tb2) shown in (c) Figure 3 The first state (period Ta1) shown in (a) and the like are switched sequentially.

[0057] In the setting Figure 3 During the first state Ta1 shown in (a), the voltage Vs1 of the first power supply 11 is lower than the output voltage Vo of the power supply device 1. Figure 4 As shown, the current Is1 flowing in the first power supply 11 (at Figure 3 The current flowing in the current loop LP11 shown in (a) decreases. Specifically, when the reactance of the first inductor 14 is set to L1, the reduction rate of the current Is1 is expressed by dIs1 / dt=(Vs1-Vo) / L1. In contrast, the voltage Vs2 of the second power supply 12 is higher than 0. Therefore, as Figure 4 As shown, the current Is2 flowing in the second power supply 12 (at Figure 3 Specifically, when the reactance of the second reactor 15 is L2, the rate of increase of the current Is2 is represented by dIs2 / dt=Vs2 / L2.

[0058] In the setting Figure 3 During the second state Tb1 shown in (b), the voltage Vs1 of the first power supply 11 is higher than 0. Figure 4As shown, the current Is1 flowing in the first power supply 11 (at Figure 3 The current flowing in the current loop LP13 shown in (b) increases. Specifically, the rate of increase of the current Is1 is expressed by dIs1 / dt=Vs1 / L1. In contrast, the voltage Vs2 of the second power supply 12 is lower than the output voltage Vo of the power supply device 1. Therefore, as Figure 4 As shown, the current Is2 flowing in the second power supply 12 (at Figure 3 The current flowing in the current loop LP14 shown in (b) decreases. Specifically, the rate of decrease of the current Is2 is represented by dIs2 / dt=(Vs2-Vo) / L2.

[0059] In the setting Figure 3 During the period Ta2 and the period Tb2 of the third state shown in (c), the voltage Vs1 of the first power supply 11 and the voltage Vs2 of the second power supply 12 are both lower than the output voltage Vo of the power supply device 1. Figure 4 As shown, the current Is1 flowing in the first power supply 11 (at Figure 3 The current flowing in the current loop LP11 shown in (c) and the current Is2 flowing in the second power supply 12 (in Figure 3 Specifically, the rate of decrease of current Is1 is represented by dIs1 / dt=(Vs1-Vo) / L1, and the rate of decrease of current Is2 is represented by dIs2 / dt=(Vs2-Vo) / L2.

[0060] Here, the voltage Vs1 of the first power supply 11 and the voltage Vs2 of the second power supply 12 are set to voltage Vs (Vs1=Vs2=Vs). The reactance L1 of the first reactor 14 and the reactance L2 of the second reactor 15 are set to reactance L (L1=L2=L). Figure 3 The length Ta of the first state period Ta1 shown in (a) and Figure 3 The length Tb of the second state period Tb1 shown in (b) is set to length T (Ta=Tb=T). In addition, the length T of the above period Ta1 or the above period Tb1 is set to length T relative to the switching period Tf (refer to Figure 4 ) is set to 0.5 or less (T / Tf<0.5). Thus, the amplitude ΔI_1 of the current Is1 flowing through the first power supply 11 and the amplitude ΔI_2 of the current Is2 flowing through the second power supply 12 are expressed by ΔI_1=ΔI_2=Vs×T / L.

[0061] Figure 5 This is a diagram showing the relationship between the amplitude and the ratio (T / Tf) of the current flowing when the power supply device according to one embodiment of the present invention operates in the heating mode. Figure 5When operating in the heating mode, the amplitude ΔI of the current Is1 flowing through the first power source 11 and the current Is2 flowing through the second power source 12 is proportional to the ratio (T / Tf). Note that the amplitude ΔI is zero when the ratio (T / Tf) is 0 and reaches its maximum value when the ratio (T / Tf) is 0.5.

[0062] That is, with Figure 4 As the ratio of the period Ta2 to the period Tb2 in the switching cycle Tf shown increases, the amplitude ΔI of the current Is1 flowing through the first power supply 11 and the current Is2 flowing through the second power supply 12 decreases. Figure 4 As the ratio of the period Ta2 to the period Tb2 in the switching cycle Tf shown in FIG. 1 decreases, the amplitude ΔI of the current Is1 flowing through the first power supply 11 and the current Is2 flowing through the second power supply 12 increases. Therefore, in order to efficiently heat the first power supply 11 and the second power supply 12, it is desirable to make Figure 4 The ratio of the period Ta2 to the period Tb2 in the switching cycle Tf shown is as small as possible.

[0063] By conducting Figure 4 The switching shown alternately performs a voltage boost operation of the first power supply 11 and a voltage boost operation of the second power supply 12 while at least one of the first power supply 11 and the second power supply 12 is connected between the first node N1 and the second node N2. This allows high-frequency current to flow through the first power supply 11 and the second power supply 12, thereby allowing the first power supply 11 and the second power supply 12 to be heated more efficiently than before without incurring a cost increase.

[0064] Voltage Balance Mode

[0065] 《First Voltage Balancing Mode》

[0066] Figure 6 FIG. 1 is a diagram showing a current path when the power supply device according to one embodiment of the present invention operates in the first voltage balance mode. Figure 6 In, with Figure 2 、 3 Similarly, the voltage detection units 17 and 18, the control device 19, and the electrical load are omitted. The first voltage balance mode is performed to equalize the voltage Vs1 of the first power supply 11 and the voltage Vs2 of the second power supply 12 when the voltage Vs1 of the first power supply 11 is higher than the voltage Vs2 of the second power supply 12. In the first voltage balance mode, the first control unit 19a of the control device 19 controls the switch circuit 13 to alternately switch Figure 6 The energy transfer state shown in (a) is the same as Figure 6 (b) shows the energy recovery state.

[0067] Here, Figure 6 The energy transfer state shown in (a) is a state in which the first power source 11 and the second power source 12 are connected in parallel. Figure 6 The energy recovery state shown in (b) is a state in which the first power supply 11 is connected via the capacitor 16 , the third switching element SW3 , and the first reactor 14 , and the second power supply 12 is connected to both ends of the second reactor 15 .

[0068] exist Figure 6 In the energy transfer state shown in (a), electric energy is transferred from the higher-voltage first power source 11 to the second power source 12. However, when the voltage difference between the first power source 11 and the second power source 12 is large, the peak value Ip of the current flowing through the first power source 11 and the second power source 12 increases. Therefore, when the magnitude of the current flowing through the first power source 11 and the second power source 12 reaches a certain value, the transfer of electric energy from the higher-voltage first power source 11 to the second power source 12 is stopped, and the system transitions to the energy recovery state.

[0069] exist Figure 6 In the energy recovery state shown in (b), in order to reduce the increased peak value Ip of the current flowing through the first power supply 11 and the second power supply 12 , the electric energy stored in the first reactor 14 and the second reactor 15 is recovered to the first power supply 11 and the second power supply 12 , respectively. Figure 6 The energy recovery state shown continues until both the current IS1 flowing through the first power source 11 and the current Is2 flowing through the second power source 12 become zero.

[0070] like Figure 6 As shown in (a) of FIG. 1 , the first control unit 19a performs control (first control) to close (turn on) the first switching element SW1 and open (turn off) the second and third switching elements SW2 and SW3, thereby achieving the aforementioned energy transfer state. In the energy transfer state, a current loop LP20 is formed, which sequentially passes through the first power supply 11, the first switching element SW1, the second reactor 15, the second power supply 12, the third switching element SW3, and the first reactor 14. Current loop LP20 is the current path when the first power supply 11 and the second power supply 12 are connected in parallel.

[0071] like Figure 6As shown in (b), the first control unit 19a switches the first through third switching elements SW1 through SW3 to the aforementioned energy recovery state by performing control (second control) to turn them off (off). In the energy recovery state, a current loop LP21 is formed, sequentially passing through the first power supply 11, capacitor 16, third switching element SW3, and first reactor 14. A current loop LP22 is also formed, sequentially passing through the second power supply 12, third switching element SW3, second switching element SW2, and second reactor 15. Current loop LP21 is the current path when the first power supply 11 is connected to both ends of the first reactor 14, while current loop LP22 is the current path when the second power supply 12 is connected to both ends of the second reactor 15.

[0072] Figure 7 1 is a diagram showing the current change when the power supply device according to one embodiment of the present invention operates in the first voltage balance mode. Figure 7 In the Figure 6 The period of the energy transfer state shown in (a) is set as period Tc1, and Figure 6 The period of the energy recovery state shown in (b) is set as period Tc2. Figure 7 As shown in FIG. 1 , the first control unit 19a controls the first switching element SW1 to the third switching element SW3 of the switching circuit 13 to alternately switch Figure 6 The energy transfer state shown in (a) is the same as Figure 6 (b) shows the energy recovery state.

[0073] In the setting Figure 6 During the energy transfer state period Tc1 shown in (a), current Is1 flowing through first power source 11 decreases, while current Is2 flowing through second power source 12 increases. When the time from the start of period Tc1 is t, current Is2 flowing through second power source 12 is expressed as Is2 = (Vs1 - Vs2) / (L1 + L2) × t. When the length of period Tc1 is t_c1, the peak value Ip of current Is flowing through first power source 11 and second power source 12 is expressed as Ip = (Vs1 - Vs2) / (L1 + L2) × t_c1.

[0074] In the setting Figure 6During the energy recovery state (Tc2) shown in (b), current Is1 flowing through the first power supply 11 and current Is2 flowing through the second power supply 12 both decrease and reach zero. The time required for current Is1 flowing through the first power supply 11 to reach zero is represented by Vs1 / L1×Ip. The time required for current Is2 flowing through the second power supply 12 to reach zero is represented by Vs2 / L2×Ip. Therefore, the time t_c2 required for current Is1 flowing through the first power supply 11 and current Is2 flowing through the second power supply 12 to reach zero is the larger of Vs1 / L1×Ip and Vs2 / L2×Ip.

[0075] When conducting Figure 7 When switching as shown, as shown in the figure, the voltage Vs1 of the first power supply 11 gradually decreases, while the voltage Vs2 of the second power supply 12 gradually increases. Figure 7 By switching as shown, the voltage Vs1 of the first power supply 11 becomes equal to the voltage Vs2 of the second power supply 12. In this way, by performing control in the first voltage balance mode (first voltage balance control), the voltage Vs1 of the first power supply 11 becomes equal to the voltage Vs2 of the second power supply 12.

[0076] Second voltage balancing mode

[0077] Figure 8 FIG. 1 is a diagram showing a current path when the power supply device according to one embodiment of the present invention operates in the second voltage balance mode. Figure 8 In, with Figure 2 、 3 6, the voltage detection units 17, 18, the control device 19, and the electrical load are omitted. The second voltage balance mode is performed to make the voltage Vs1 of the first power supply 11 equal to the voltage Vs2 of the second power supply 12 when the voltage Vs2 of the second power supply 12 is higher than the voltage Vs1 of the first power supply 11. In the second voltage balance mode, the first control unit 19a of the control device 19 controls the switch circuit 13 to alternately switch Figure 8 The energy transfer state shown in (a) is the same as Figure 8 (b) shows the energy recovery state.

[0078] Here, Figure 8 The energy transfer state shown in (a) is the same as Figure 6 Similarly, in the energy transfer state shown in (a), the first power source 11 and the second power source 12 are connected in parallel. Figure 8 The energy recovery state shown in (b) is a state in which the first power supply 11 is connected to both ends of the first reactor 14 and the second power supply 12 is connected via the second reactor 15 , the first switching element SW1 , and the capacitor 16 .

[0079] exist Figure 8 In the energy transfer state shown in (a), electric energy is transferred from the second power supply 12 with a higher voltage to the first power supply 11. Figure 8 In the energy recovery state shown in (b), in order to reduce the increased peak value Ip of the current flowing through the first power supply 11 and the second power supply 12 , the electric energy stored in the first reactor 14 and the second reactor 15 is recovered to the first power supply 11 and the second power supply 12 , respectively.

[0080] like Figure 8 As shown in (a) of FIG. 1 , the first control unit 19a performs control (third control) to open the first and second switching elements SW1 and SW2 and close the third switching element SW3, thereby achieving the aforementioned energy transfer state. In the energy transfer state, a current loop LP30 is formed, sequentially passing through the first power supply 11, the first reactor 14, the third switching element SW3, the second power supply 12, the second reactor 15, and the first switching element SW1. Current loop LP30 is the current path when the first power supply 11 and the second power supply 12 are connected in parallel.

[0081] like Figure 8 As shown in (b), the first control unit 19a switches the first through third switching elements SW1 through SW3 to the aforementioned energy recovery state by performing control (second control) to turn them off (off). In the energy recovery state, a current loop LP31 is formed, sequentially passing through the first power supply 11, the first reactor 14, the second switching element SW2, and the first switching element SW1. A current loop LP32 is also formed, sequentially passing through the second power supply 12, the second reactor 15, the first switching element SW1, and the capacitor 16. Current loop LP31 is the current path when the first power supply 11 is connected to both ends of the first reactor 14, while current loop LP32 is the current path when the second power supply 12 is connected via the second reactor 15 and the capacitor 16.

[0082] Figure 9 1 is a diagram showing the current change when the power supply device according to one embodiment of the present invention operates in the second voltage balance mode. Figure 9 In the Figure 8 The period of the energy transfer state shown in (a) is set as period Td1, and Figure 8 The period of the energy recovery state shown in (b) is set as period Td2. Figure 9 As shown in FIG. 1 , the first control unit 19a controls the first switching element SW1 to the third switching element SW3 of the switching circuit 13 to alternately switch Figure 8 The energy transfer state shown in (a) is the same as Figure 8(b) shows the energy recovery state.

[0083] In the setting Figure 8 During the energy transfer state period Td1 shown in (a), current Is2 flowing through second power supply 12 decreases, while current Is1 flowing through first power supply 11 increases. When the time from the start of period Td1 is t, current Is1 flowing through first power supply 11 is expressed as Is1 = (Vs2 - Vs1) / (L1 + L2) × t. When the length of period Td1 is t_d1, the peak value Ip of current Is flowing through first power supply 11 and second power supply 12 is expressed as Ip = (Vs2 - Vs1) / (L1 + L2) × t_d1.

[0084] In the setting Figure 8 During the energy recovery state period Td2 shown in (b) of FIGURE 2, current Is1 flowing through first power supply 11 and current Is2 flowing through second power supply 12 both decrease and reach zero. Note that the time t_d2 required for current Is1 flowing through first power supply 11 and current Is2 flowing through second power supply 12 to reach zero is the larger of Vs1 / L1×Ip and Vs2 / L2×Ip, similar to the time t_c2 when operating in the first voltage balancing mode.

[0085] When conducting Figure 9 When switching as shown, as shown in the figure, the voltage Vs2 of the second power supply 12 gradually decreases, while the voltage Vs1 of the first power supply 11 gradually increases. Figure 9 By switching as shown, the voltage Vs1 of the first power supply 11 becomes equal to the voltage Vs2 of the second power supply 12. In this way, by performing control in the second voltage balance mode (second voltage balance control), the voltage Vs1 of the first power supply 11 becomes equal to the voltage Vs2 of the second power supply 12.

[0086] Figure 10 This is a flowchart showing the processing when voltage balance control is performed in the power supply device according to one embodiment of the present invention. Figure 10 The flowchart shown is started, for example, every time a host device (not shown) issues an instruction to switch to a parallel connection to the control device 19 of the power supply device 1. Such a switching instruction is issued, for example, when the vehicle is started.

[0087] When the process starts, the first control unit 19a of the control device 19 determines whether the difference (voltage difference) between the voltage Vs1 of the first power supply 11 detected by the voltage detection unit 17 and the voltage Vs2 of the second power supply 12 detected by the voltage detection unit 18 is greater than a predetermined reference value (step S11). If the first control unit 19a determines that the voltage difference is not greater than the reference value, the process ends. Figure 10 On the other hand, when the first control unit 19a determines that the voltage difference is equal to or greater than the reference value, it determines whether the state instructed by the host device is the parallel state (step S12).

[0088] When the first control unit 19a determines that the state instructed by the host device is not the parallel state, the first control unit 19a ends the operation. Figure 10 In contrast, when the first control unit 19a determines that the state indicated by the host device is the parallel state, it determines whether the value obtained by subtracting the voltage Vs2 of the second power supply 12 from the voltage Vs1 of the first power supply 11 (hereinafter referred to as the first potential difference) is smaller than a predetermined threshold value (step S13).

[0089] When the first control unit 19a determines that the first potential difference is not smaller than the threshold value (is greater than the threshold value), the first control unit 19a switches to using Figure 6 、 7 The first voltage balance mode described above is used to perform the first voltage balance control (step S14). It should be noted that the first control unit 19a performs the first voltage balance control in step S14 until it is determined in step S13 that the first potential difference is less than the threshold. If the first control unit 19a determines that the first potential difference is less than the threshold, it then determines whether the value obtained by subtracting the voltage Vs1 of the first power supply 11 from the voltage Vs2 of the second power supply 12 (hereinafter referred to as the second potential difference) is less than a predetermined threshold (step S15).

[0090] When the first control unit 19a determines that the second potential difference is not smaller than the threshold value (is greater than the threshold value), the first control unit 19a switches to using Figure 8 、 9 The second voltage balance mode described above is used to perform the second voltage balance control (step S16). It should be noted that the first control unit 19a performs the second voltage balance control in step S16 until it is determined in step S15 that the second potential difference is smaller than the threshold value. In contrast, if the first control unit 19a determines that the second potential difference is smaller than the threshold value, it switches to Figure 2 When the above processing is completed, the first control unit 19a ends the control of the parallel state shown in (b) (step S17). Figure 10 The processing shown.

[0091] As described above, the power supply device 1 of this embodiment includes a first power supply 11 connected between a first node N1 and a second node N2, and a second power supply 12 connected between a third node N3 and a fourth node N4. The power supply device 1 supplies power to the electrical loads (such as the inverter 21, the auxiliary unit VCU 23, and the outlet 24) connected between the first node N1 and the fourth node N4.

[0092] The power supply device 1 includes a switching circuit 13, a first reactor 14, a second reactor 15, and a control device 19. The switching circuit 13 includes a first switching element SW1 connected between a first node N1 and a third node N3, a second switching element SW2 connected between a second node N2 and a third node N3, and a third switching element SW3 connected between the second node N2 and a fourth node N4. The first reactor 14 is arranged between the first power supply 11 and the first node N1 or the second node N2, and the second reactor 15 is arranged between the second power supply 12 and the third node N3 or the fourth node N4.

[0093] The control device 19 alternately switches between a first state and a second state. The first state is a state in which the first power supply 11 is connected between the first node N1 and the fourth node N4 via the first inductor 14, and the second power supply 12 is connected to both ends of the second inductor 15. The second state is a state in which the first power supply 11 is connected to both ends of the first inductor 14.

[0094] When the control device 19 is in the first state, the second switch element SW2 and the third switch element SW3 of the switch circuit 13 are controlled to be closed, and the first switch element SW1 is controlled to be open. When the control device 19 is in the second state, the first switch element SW1 and the second switch element SW2 of the switch circuit 13 are controlled to be closed, and the third switch element SW3 is controlled to be open.

[0095] Thus, high-frequency current can flow through the first power supply 11 and the second power supply 12 simply by switching the open state and the closed state of multiple switching elements provided in the switching circuit 13, thereby making it possible to heat the first power supply 11 and the second power supply 12 more efficiently than before without incurring an increase in cost.

[0096] While the above embodiments describe specific implementations of the present invention, the present invention is in no way limited to these embodiments and various modifications and substitutions can be made without departing from the spirit of the present invention. For example, in the above embodiments, the first reactor 14 is configured between the first power supply 11 and the second node N2, and the second reactor 15 is configured between the second power supply 12 and the third node N3. However, the first reactor 14 may also be configured between the first power supply 11 and the first node N1. Similarly, the second reactor 15 may also be configured between the second power supply 12 and the fourth node N4.

[0097] The control device 19 can be implemented using a computer such as a computer. When the control device 19 is implemented using a computer, the functions of each component of the control device 19 are realized by the CPU (central processing unit) installed in the computer executing programs for implementing these functions. In other words, the functions of each component of the control device 19 are realized through the coordinated cooperation of software and hardware resources. It should be noted that the control device 19 can also be implemented using hardware such as an FPGA (Field-Programmable Gate Array), an LSI (Large Scale Integration), or an ASIC (Application Specific Integrated Circuit).

Claims

1. A power supply device comprising a first power supply connected between a first node and a second node and a second power supply connected between a third node and a fourth node, for supplying power to an electric load connected between the first node and the fourth node, wherein: The power supply device comprises: a switch circuit having a first switch connected between the first node and the third node, a second switch connected between the second node and the third node, and a third switch connected between the second node and the fourth node; a first reactor, disposed between the first power source and the first node or the second node; a second reactor disposed between the second power source and the third node or the fourth node; as well as A control device that alternately switches between a first state and a second state, wherein the first state refers to a state in which the control device controls the second switch and the third switch of the switching circuit to a closed state and controls the first switch to an open state, thereby connecting the first power supply between the first node and the fourth node via the first inductor and connecting the second power supply to both ends of the second inductor; and the second state refers to a state in which the control device controls the first switch and the second switch of the switching circuit to a closed state and controls the third switch to an open state, thereby connecting the second power supply between the first node and the fourth node via the second inductor and connecting the first power supply to both ends of the first inductor.

2. The power supply device according to claim 1, wherein When switching between the first state and the second state, the control device temporarily sets the state to a third state. The third state refers to a state in which the control device controls the first switch and the third switch to an open state and controls the second switch to a closed state, so that the first power supply is connected between the first node and the fourth node via the first inductor, and the second power supply is connected between the first node and the fourth node via the second inductor.

3. The power supply device according to claim 1, wherein The power supply device includes a voltage detection unit for detecting the voltages of the first power supply and the second power supply. When the voltage of the first power supply is greater than the voltage of the second power supply, the control device implements a balance control by alternating between a first control and a second control, wherein the first control is a control in which the first switch is set to a closed state and the second switch and the third switch are set to an open state, and the second control is a control in which the first switch, the second switch, and the third switch are set to an open state.

4. The power supply device according to claim 1, wherein The power supply device includes a voltage detection unit for detecting the voltages of the first power supply and the second power supply. When the voltage of the second power supply is greater than the voltage of the first power supply, the control device implements a balance control by alternating between a third control and a second control, wherein the third control is a control in which the first switch and the second switch are set to an open state and the third switch is set to a closed state, and the second control is a control in which the first switch, the second switch, and the third switch are set to an open state.

5. The power supply device according to claim 3 or 4, wherein: The control device is capable of switching between a parallel state and a series state. The parallel state refers to a state in which the control device controls the first switch and the third switch to be in a closed state and controls the second switch to be in an open state, so that the first power supply and the second power supply are connected in parallel between the first node and the fourth node. The series state refers to a state in which the control device controls the first switch and the third switch to be in an open state and controls the second switch to be in a closed state, so that the first power supply and the second power supply are connected in series between the first node and the fourth node. The balance control is performed when the difference between the voltage of the first power supply and the voltage of the second power supply detected by the voltage detection unit is equal to or greater than a predetermined reference value and a transition to the parallel state is instructed.

6. A method for controlling a power supply device, the power supply device comprising a first power supply connected between a first node and a second node and a second power supply connected between a third node and a fourth node, for supplying power to an electrical load connected between the first node and the fourth node, wherein: The power supply device comprises: a switch circuit having a first switch connected between the first node and the third node, a second switch connected between the second node and the third node, and a third switch connected between the second node and the fourth node; a first reactor, disposed between the first power source and the first node or the second node; as well as a second reactor disposed between the second power supply and the third node or the fourth node; The control method of the power supply device includes the following steps: alternately switching between a first state and a second state, wherein the first state refers to controlling the second switch and the third switch of the switching circuit to a closed state, and controlling the first switch to an open state, so that the first power supply is connected between the first node and the fourth node via the first inductor, and the second power supply is connected to both ends of the second inductor; and the second state refers to controlling the first switch and the second switch of the switching circuit to a closed state, and controlling the third switch to an open state, so that the second power supply is connected between the first node and the fourth node via the second inductor, and the first power supply is connected to both ends of the first inductor.

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