Power source device and control method for power source device

Abstract

To provide a power source device and a control method for the power source device that can heat multiple power sources more efficiently than conventional methods without increasing costs by supplying a high-frequency current.SOLUTION: A power source device 1 comprises a first power source 11, a second power source 12, a switching circuit 13 having first to third switching elements SW1-SW3, a first reactor 14, a second reactor 15, and a control device 19 that controls the switching circuit 13 to alternately switch between: a first state in which the first power source 11 is connected between a first node N1 and a fourth node N4 via the first reactor 14, and the second power source 12 is connected to both ends of the second reactor 15; and a second state in which the second power source 12 is connected between the first node N1 and the fourth node N4 via the second reactor 15, and the first power source 11 is connected to both ends of the first reactor 14.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a power supply device and a method for controlling a power supply device. [Background technology]

[0002] In recent years, in order to realize a low-carbon society, an increasing number of vehicles are equipped with a traction motor instead of an engine as a power source, or with a traction motor in addition to an engine. The following Patent Documents 1 and 2 disclose battery control systems that warm up the battery that supplies power to the traction motor of such vehicles. For example, the battery control system disclosed in the following Patent Document 1 includes a first battery and a second battery that have different output characteristics depending on temperature, and when the temperature of the first battery is below a predetermined temperature, the system warms up the first battery by preferentially using the second battery. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2020-092509 [Patent Document 2] Japanese Patent Application Publication No. 2023-527451 Summary of the Invention [Problem to be solved by the invention]

[0004] However, the battery control system disclosed in the above-mentioned Patent Document 1 requires two batteries with different output characteristics depending on the temperature, which leads to increased costs. Also, in the battery control system disclosed in the above-mentioned Patent Document 1, the temperature of the first battery is raised by placing the second battery around the first battery, which makes it difficult to say that the batteries are effectively heated.

[0005] The present invention has been made in consideration of the above circumstances, and aims to provide a power supply device and a control method for a power supply device that can heat multiple power sources more efficiently than conventional methods without increasing costs by passing a high-frequency current through them. [Means for solving the problem]

[0006] The power supply device and the method for controlling the power supply device according to the present invention employ the following configuration.

[0007] (1): A power supply device according to one aspect of the present invention 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 electrical load connected between the first node and the fourth node, the power supply device including 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 supply and the first node or the second node, and a second power supply connected between the second power supply and the third node or the fourth node. and a control device that alternately switches between 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 across both ends of the second reactor by controlling the second switch and the third switch of the switch circuit to a closed state and the first switch to an open state, 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 across both ends of the first reactor by controlling the first switch and the second switch of the switch circuit to a closed state and the third switch to an open state.

[0008] (2): In the aspect (1) above, when switching between the first state and the second state, the control device temporarily controls the first switch and the third switch to an open state and the second switch to a closed state, thereby establishing a third 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 between the first node and the fourth node via the second reactor.

[0009] (3): In the above aspect (1) or (2), a voltage detection unit is provided that detects the voltages of the first power source and the second power source, and the control device performs balance control that alternately performs a first control that closes the first switch and opens the second switch and the third switch, and a second control that opens the first switch, the second switch, and the third switch, when the voltage of the first power source is greater than the voltage of the second power source.

[0010] (4): In the above aspect (1) or (2), a voltage detection unit is provided that detects the voltages of the first power source and the second power source, and the control device performs balance control that alternately performs a third control that opens the first switch and the second switch and closes the third switch, and a second control that opens the first switch, the second switch, and the third switch, when the voltage of the second power source is greater than the voltage of the first power source.

[0011] (5): In the above aspect (3) or (4), the control device is capable of switching between a parallel state in which the first power source and the second power source are connected in parallel between the first node and the fourth node by controlling the first switch and the third switch to a closed state and the second switch to an open state, and a series state in which the first power source and the second power source are connected in series between the first node and the fourth node by controlling the first switch and the third switch to an open state and the second switch to a closed state, and performs the balance control when a difference between the voltage of the first power source and the voltage of the second power source 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.

[0012] (6) A control method for a power supply device according to one aspect of the present invention is a control method for 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, and 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 arranged between the first power supply and the first node or the second node, and a second switch connected between the second power supply and the third node or the fourth node. and a second reactor arranged between the first node and the fourth node, and the second power supply connected across both ends of the second reactor by controlling the second switch and the third switch of the switch circuit to a closed state and 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 reactor and the second power supply is connected across both ends of the second reactor, and a second state by controlling the first switch and the second switch of the switch circuit to a closed state and 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 reactor and the first power supply is connected across both ends of the first reactor. [Effects of the Invention]

[0013] According to aspects (1) and (6), the open and closed states of the switches provided in the switch circuit are controlled to alternate between the first state and the second state, thereby allowing a high-frequency current to flow through the first power source and the second power source, thereby making it possible to heat the first power source and the second power source more efficiently than before without increasing costs.

[0014] According to the aspect (2), when switching between the first state and the second state, the first switch and the third switch are temporarily set to the open state and the second switch is temporarily set to the closed state, thereby preventing the first switch and the third switch from being simultaneously set to the closed state.

[0015] According to the aspects (3) and (4), balance control is performed according to 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.

[0016] According to the aspect (5), 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 a parallel state is instructed, balance control is performed, thereby making it possible to suppress the short-circuit current when transitioning to the parallel state. [Brief explanation of the drawings]

[0017] [Figure 1] 1 is a circuit diagram showing a configuration of a main part of a power supply device according to an embodiment of the present invention; [Figure 2] 3 is a diagram showing current paths when a power supply device according to an embodiment of the present invention is operating in series mode or parallel mode. FIG. [Figure 3] FIG. 4 is a diagram showing a current path when a power supply device according to an embodiment of the present invention is operating in a heating mode. [Figure 4] FIG. 10 is a diagram showing current changes when the power supply device according to the embodiment of the present invention is operating in a heating mode. [Figure 5]FIG. 10 is a diagram showing the relationship between the amplitude of the current that flows when the power supply device according to one embodiment of the present invention is operating in a heating mode and the ratio (T / Tf). [Figure 6] 3 is a diagram showing current paths when the power supply device according to one embodiment of the present invention is operating in a first voltage balancing mode. FIG. [Figure 7] FIG. 4 is a diagram showing current changes when the power supply device according to one embodiment of the present invention is operating in a first voltage balancing mode. [Figure 8] FIG. 4 is a diagram showing current paths when the power supply device according to one embodiment of the present invention is operating in a second voltage balancing mode. [Figure 9] FIG. 6 is a diagram showing current changes when the power supply device according to one embodiment of the present invention is operating in a second voltage balancing mode. [Figure 10] 5 is a flowchart showing a process when voltage balance control is performed in the power supply device according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0018] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 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 drawings.

[0019] <Power supply> Fig. 1 is a circuit diagram showing the configuration of the main parts of a power supply device according to one embodiment of the present invention. As shown in Fig. 1, the power supply device 1 according to this embodiment includes a first power source 11, a second power source 12, a switch circuit 13, a first reactor 14, a second reactor 15, a capacitor 16, voltage detection units 17 and 18, and a control device 19. Such a power supply device 1 supplies DC power to an electrical load connected via, for example, a contactor 20.

[0020] Here, examples of the electrical loads to which DC power is supplied from the power supply device 1 include an inverter 21 that controls power running and regeneration of an electric motor M that generates driving force for the vehicle, an auxiliary device 22 and an auxiliary device VCU (Voltage Control Unit) 23 provided in the vehicle, and an inlet 24 provided in the vehicle. Note that, for example, a three-phase brushless DC motor or the like can be used as the electric motor M. Furthermore, the auxiliary device VCU 23 is a device that controls the voltage applied to the auxiliary device 22.

[0021] The first power source 11 is a chargeable and dischargeable secondary battery (for example, a battery). The positive terminal of the first power source 11 is connected to a first node N1, and the negative terminal is connected to a second node N2. The second power source 12 is a chargeable and dischargeable secondary battery (for example, a battery). The positive terminal of the second power source 12 is connected to a third node N3, and the negative terminal is connected to a fourth node N4. The first power source 11 and the second power source 12 are the same power source, and the voltage Vs1 of the first power source 11 and the voltage Vs2 of the second power source 12 are equal (or almost equal). The voltage Vs1 of the first power source 11 and the voltage Vs2 of the second power source 12 are voltages (for example, 400 V) suitable for operating the auxiliary device 22.

[0022] One end of the above-mentioned electrical load (the inverter 21, the auxiliary 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.

[0023] The switch circuit 13 includes three switching elements (first switching element SW1 to third switching element SW3 (first switch to third switch)) connected in series, and switches the connection states of the first power supply 11, the second power supply 12, and the electrical load under the control of the control device 19. The first switching element SW1 is connected between the first node N1 and the third node N3, and the second switching element SW2 is connected between the second node N2 and the third node N3. The third switching element SW3 is connected between the second node N2 and the fourth node N4.

[0024] Here, for example, MOSFETs (Metal-Oxide-Semiconductor Field-Effect Transistors) can be used as the first switching element SW1 to the third switching element SW3. When MOSFETs are used as the first switching element SW1 to the third switching element SW3, the specific connection relationships are 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. Note that a diode is connected between the source and drain of each of the first switching element SW1 to the third switching element SW3 in the forward direction from the source to the drain.

[0025] The switching of the switch circuit 13 is controlled by, for example, a pulse width modulated (PWM) signal that is output from the control device 19 and input to the gates of the first to third switching elements SW1 to SW3. A specific switching control method for the switch circuit 13 will be described later.

[0026] 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.

[0027] The capacitor 16 is connected between the first node N1 and the fourth node N4. Specifically, one electrode of the capacitor 16 is connected to the first node N1, and the other electrode is connected to the fourth node N4. The capacitor 16 is provided to smooth the current output from the power supply device 1. The voltage detection unit 17 detects the voltage Vs1 of the first power supply 11 and outputs the detection result to the control device 19. The voltage detection unit 18 detects the voltage Vs2 of the second power supply 12 and outputs the detection result to the control device 19.

[0028] The control device 19 includes, for example, a first control unit 19a and a second control unit 19b, and performs switching control of the switch circuit 13 and control of the electric load (for example, drive control of the inverter 21). The first control unit 19a performs switching control of the switch circuit 13 to switch the connection states of the first power source 11, the second power source 12, and the electric load.

[0029] Here, the power supply device 1 of this embodiment has a parallel mode and a series mode as its operating modes. The parallel mode is a mode in which the first power supply 11 and the second power supply 12 operate in a state in which they are connected in parallel to an electrical load (parallel state). The series mode is a mode in which the first power supply 11 and the second power supply 12 operate in a state in which they are connected in series to an electrical load (series state). The first control unit 19a controls the switch circuit 13 to switch between the parallel mode and the series mode.

[0030] In addition to the parallel mode and serial mode, the operating modes include a heating mode and a voltage balance mode. The heating mode is an operating mode in which the first power source 11 and the second power source 12 are heated using a chopper method. The voltage balance mode is an operating mode in which the voltage of the first power source 11 and the voltage of the second power source 12 are made equal. If the voltage of the first power source 11 and the voltage of the second power source 12 differ, a short-circuit current will flow from one of the first power source 11 and the second power source 12 to the other. To prevent this, the voltage balance mode is implemented. The operating modes and operating states of the power supply device 1 will be described in detail later.

[0031] The second control unit 19b controls the electrical load to which DC power is supplied from the power supply device 1. For example, during power running of the electric 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 to each phase of the electric motor M to pass each phase of the AC current. On the other hand, during regenerative running of the electric motor M, the second control unit 19b converts the AC generated power output from the electric motor M into DC power while maintaining synchronization based on the rotation angle of the electric motor M.

[0032] <Series mode and parallel mode> Figure 2 is a diagram showing current paths when a power supply device according to an embodiment of the present invention is operating in series mode or parallel mode. Voltage detection units 17 and 18, a control device 19, and an electrical load are not shown in Figure 2. Figure 2(a) is a diagram showing current paths when operating in series mode, and Figure 2(b) is a diagram showing current paths when operating in parallel mode.

[0033] As shown in FIG. 2(a), in the series mode, the first control unit 19a of the control device 19 closes (ON) the second switching element SW2 and opens (OFF) the first switching element SW1 and the third switching element SW3. As a result, as shown in FIG. 2(a), a current loop LP1 is formed that passes through the fourth node N4, the second power supply 12, the second reactor 15, the second switching element SW2, the first reactor 14, the first power supply 11, and the first node N1 in this order. 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. During regeneration, a current flows in the direction opposite to that of the current loop LP1 shown in FIG. 2(a).

[0034] As shown in FIG. 2(b), in the parallel mode, the first control unit 19a of the control device 19 closes (ON) the first switching element SW1 and the third switching element SW3 and opens (OFF) the second switching element SW2. As a result, as shown in FIG. 2(b), a current loop LP2 is formed that passes through the fourth node N4, the third switching element SW3, the first reactor 14, the first power supply 11, and the first node N1 in this order, and a current loop LP3 is formed that passes through the fourth node N4, the second power supply 12, the second reactor 15, the first switching element SW1, and the first node N1 in this order. In other words, 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. During regeneration, a current flows in the direction opposite to that of the current loops LP2 and LP3 shown in FIG. 2(b).

[0035] <Heating mode> Figure 3 is a diagram showing a current path when a power supply device according to one embodiment of the present invention is operating in a heating mode. Similar to Figure 2, voltage detection units 17 and 18, control device 19, and electrical loads are not shown in Figure 3. In the heating mode, first control unit 19a of control device 19 controls switch circuit 13 to alternately switch between a first state shown in Figure 3(a) and a second state shown in Figure 3(b). The switching frequency between the first state and the second state is, for example, several tens to several hundreds of kHz.

[0036] Here, when switching from the first state shown in Fig. 3(a) to the second state shown in Fig. 3(b), the first control unit 19a first sets the state to the third state shown in Fig. 3(c) and then switches to the second state shown in Fig. 3(b). Also, when switching from the second state shown in Fig. 3(b) to the first state shown in Fig. 3(a), the first control unit 19a first sets the state to the third state shown in Fig. 3(c) and then switches to the first state shown in Fig. 3(a).

[0037] Here, 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 reactor 14, and the second power supply 12 is connected across the second reactor 15. The second state 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 reactor 15, and the first power supply 11 is connected across the first reactor 14. The third 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 reactor 14, and the second power supply 12 is connected between the first node N1 and the fourth node N4 via the second reactor 15. As can be seen from FIGS. 3(a) to 3(c), in the heating mode, 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.

[0038] As shown in FIG. 3A, the first control unit 19a sets the first state described above by opening the first switching element SW1 (OFF) and closing the second switching element SW2 and the third switching element SW3 (ON). In the first state, a current loop LP11 is formed, which passes through the third switching element SW3, the first reactor 14, the first power supply 11, and the capacitor 16 in this order. A current loop LP12 is also formed, which passes through the second power supply 12, the second reactor 15, the second switching element SW2, and the third switching element SW3 in this order. The current loop LP11 is a 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. The current loop LP12 is a current path when the second power supply 12 is connected across the second reactor 15.

[0039] 3(b), the first control unit 19a sets the first switching element SW1 and the second switching element SW2 to a closed state (ON) and the third switching element SW3 to an open state (OFF), thereby setting the second state described above. In the second state, a current loop LP13 is formed, which passes through the first power supply 11, the first switching element SW1, the second switching element SW2, and the first reactor 14 in this order. A current loop LP14 is also formed, which passes through the second power supply 12, the second reactor 15, the first switching element SW1, and the capacitor 16 in this order. The current loop LP13 is a current path when the first power supply 11 is connected to both ends of the first reactor 14. The current loop LP14 is a 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.

[0040] As shown in Fig. 3(c), the first control unit 19a sets the first switching element SW1 and the third switching element SW3 to the open state (OFF) and the second switching element SW2 to the closed state (ON), thereby setting the third state described above. In the third state, a current loop LP11 shown in Fig. 3(a) and a current loop LP14 shown in Fig. 3(b) are formed. 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.

[0041] Figure 4 is a diagram showing current changes when a power supply device according to an embodiment of the present invention is operating in a heating mode. In Figure 4, the period during which the first state shown in Figure 3(a) is set is designated as period Ta1, and the period during which the second state shown in Figure 3(b) is set is designated as period Tb1. Furthermore, when switching from the first state shown in Figure 3(a) to the second state shown in Figure 3(b), the period during which the third state shown in Figure 3(c) is temporarily set is designated as period Ta2. Furthermore, when switching from the second state shown in Figure 3(b) to the first state shown in Figure 3(a), the period during which the third state shown in Figure 3(c) is temporarily set is designated as period Tb2.

[0042] 4, the first control unit 19a controls the first switching element SW1 to the third switching element SW3 of the switch circuit 13 to switch between the states shown in Fig. 3(a) to Fig. 3(c). Specifically, the first control unit 19a sequentially switches between the first state (period Ta1) shown in Fig. 3(a), the third state (period Ta2) shown in Fig. 3(c), the second state (period Tb1) shown in Fig. 3(b), the third state (period Tb2) shown in Fig. 3(c), the first state (period Ta1) shown in Fig. 3(a), and so on.

[0043] During a period Ta1 in the first state shown in FIG. 3(a), the voltage Vs1 of the first power supply 11 is lower than the output voltage Vo of the power supply device 1. Therefore, as shown in FIG. 4, the current Is1 flowing through the first power supply 11 (the current flowing through the current loop LP11 shown in FIG. 3(a)) decreases. Specifically, if the reactance of the first reactor 14 is L1, the rate of decrease of the current Is1 is expressed as dIs1 / dt=(Vs1-Vo) / L1. In contrast, the voltage Vs2 of the second power supply 12 is higher than 0. Therefore, as shown in FIG. 4, the current Is2 flowing through the second power supply 12 (the current flowing through the current loop LP12 shown in FIG. 3(a)) increases. Specifically, if the reactance of the second reactor 15 is L2, the rate of increase of the current Is2 is expressed as dIs2 / dt=Vs2 / L2.

[0044] During a period Tb1 in the second state shown in FIG. 3(b), the voltage Vs1 of the first power supply 11 is higher than 0. Therefore, as shown in FIG. 4, the current Is1 flowing through the first power supply 11 (the current flowing through the current loop LP13 shown in FIG. 3(b)) increases. Specifically, the rate of increase of the current Is1 is expressed as 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 shown in FIG. 4, the current Is2 flowing through the second power supply 12 (the current flowing through the current loop LP14 shown in FIG. 3(b)) decreases. Specifically, the rate of decrease of the current Is2 is expressed as dIs2 / dt=(Vs2-Vo) / L2.

[0045] During periods Ta2 and Tb2 in the third state shown in Fig. 3(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. Therefore, as shown in Fig. 4, the current Is1 flowing through the first power supply 11 (the current flowing through the current loop LP11 shown in Fig. 3(c)) and the current Is2 flowing through the second power supply 12 (the current flowing through the current loop LP14 shown in Fig. 3(c)) decrease. Specifically, the rate of decrease of the current Is1 is expressed as dIs1 / dt = (Vs1 - Vo) / L1, and the rate of decrease of the current Is2 is expressed as dIs2 / dt = (Vs2 - Vo) / L2.

[0046] Here, the voltage Vs1 of the first power supply 11 and the voltage Vs2 of the second power supply 12 are defined as voltages Vs (Vs1 = Vs2 = Vs). The reactance L1 of the first reactor 14 and the reactance L2 of the second reactor 15 are defined as reactances L (L1 = L2 = L). Furthermore, the length Ta of the period Ta1 in the first state shown in FIG. 3(a) and the length Tb of the period Tb1 in the second state shown in FIG. 3(b) are defined as lengths T (Ta = Tb = T). Furthermore, the ratio of the length T of the period Ta1 or Tb1 to the switching period Tf (see FIG. 4) is assumed to be 0.5 or less (T / Tf<0.5). Then, 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 as ΔI_1 = ΔI_2 = Vs × T / L.

[0047] 5 is a diagram showing the relationship between the amplitude of the current flowing when a power supply device according to one embodiment of the present invention is operating in the heating mode and the ratio (T / Tf). Referring to FIG. 5, when operating in the heating mode, 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 is proportional to the ratio (T / Tf). Note that the amplitude ΔI is 0 when the ratio (T / Tf) is 0, and is maximum when the ratio (T / Tf) is 0.5.

[0048] That is, as the proportions of the periods Ta2 and Tb2 in the switching cycle Tf shown in Fig. 4 increase, the amplitude ΔI of the current Is1 flowing in the first power supply 11 and the current Is2 flowing in the second power supply 12 decreases. On the other hand, as the proportions of the periods Ta2 and Tb2 in the switching cycle Tf shown in Fig. 4 decrease, the amplitude ΔI of the current Is1 flowing in the first power supply 11 and the current Is2 flowing in the second power supply 12 increases. For this reason, in order to efficiently heat the first power supply 11 and the second power supply 12, it is desirable to make the proportions of the periods Ta2 and Tb2 in the switching cycle Tf shown in Fig. 4 as small as possible.

[0049] 4, the first power supply 11 and the second power supply 12 alternately perform a boost operation 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 a high frequency current to flow through the first power supply 11 and the second power supply 12, making it possible to heat the first power supply 11 and the second power supply 12 more efficiently than before without increasing costs.

[0050] <Voltage balance mode> <First voltage balance mode> FIG. 6 is a diagram showing current paths when a power supply device according to an embodiment of the present invention is operating in the first voltage balance mode. As with FIGS. 2 and 3, FIG. 6 omits the illustration of voltage detection units 17 and 18, control device 19, and electrical loads. The first voltage balance mode is implemented to equalize voltages Vs1 and Vs2 of first and second power supplies 11 and 12 when voltage Vs1 of first and second power supplies 11 and 12 is higher than voltage Vs2 of second power supplies 12. In the first voltage balance mode, first control unit 19a of control device 19 controls switch circuit 13 to alternate between the energy transfer state shown in FIG. 6(a) and the energy recovery state shown in FIG. 6(b).

[0051] 6(a) is a state in which the first power source 11 and the second power source 12 are connected in parallel. The energy recovery state shown in FIG. 6(b) is a state in which the first power source 11 is connected via the capacitor 16, the third switching element SW3, and the first reactor 14, and the second power source 12 is connected across the second reactor 15.

[0052] 6(a), electrical energy is transferred from the first power supply 11, which has a higher voltage, to the second power supply 12. However, when the voltage difference between the first power supply 11 and the second power supply 12 is large, the peak value Ip of the current flowing through the first power supply 11 and the second power supply 12 becomes large. Therefore, when the magnitude of the current flowing through the first power supply 11 and the second power supply 12 reaches a certain value, the state transitions to an energy recovery state in order to stop the transfer of electrical energy from the first power supply 11, which has a higher voltage, to the second power supply 12.

[0053] 6(b), in order to reduce the increased peak value Ip of the current flowing through the first power source 11 and the second power source 12, the electrical energy stored in the first reactor 14 and the second reactor 15 is recovered to the first power source 11 and the second power source 12, respectively. The energy recovery state shown in FIG. 6 continues until the current IS1 flowing through the first power source 11 and the current Is2 flowing through the second power source 12 both become zero.

[0054] 6(a), the first control unit 19a performs control (first control) to close the first switching element SW1 (ON) and open the second switching element SW2 and the third switching element SW3 (OFF), thereby establishing the above-described energy transfer state. In the energy transfer state, a current loop LP20 is formed that passes through the first power source 11, the first switching element SW1, the second reactor 15, the second power source 12, the third switching element SW3, and the first reactor 14 in this order. The current loop LP20 is a current path in a state in which the first power source 11 and the second power source 12 are connected in parallel.

[0055] 6(b), the first control unit 19a performs control (second control) to open (OFF) the first switching element SW1 to the third switching element SW3, thereby establishing the above-described energy recovery state. In the energy recovery state, a current loop LP21 is formed, which passes through the first power supply 11, the capacitor 16, the third switching element SW3, and the first reactor 14 in this order. In addition, a current loop LP22 is also formed, which passes through the second power supply 12, the third switching element SW3, the second switching element SW2, and the second reactor 15 in this order. The current loop LP21 is a current path when the first power supply 11 is connected to both ends of the first reactor 14, and the current loop LP22 is a current path when the second power supply 12 is connected to both ends of the second reactor 15.

[0056] Fig. 7 is a diagram showing current changes when a power supply device according to one embodiment of the present invention is operating in the first voltage balance mode. In Fig. 7, the period during which the energy transfer state shown in Fig. 6(a) is set is referred to as period Tc1, and the period during which the energy recovery state shown in Fig. 6(b) is set is referred to as period Tc2. As shown in Fig. 7, the first control unit 19a controls the first switching element SW1 to the third switching element SW3 of the switch circuit 13 to alternately switch between the energy transfer state shown in Fig. 6(a) and the energy recovery state shown in Fig. 6(b).

[0057] 6(a), during period Tc1, which is the energy transfer state, current Is1 flowing through first power supply 11 decreases, while current Is2 flowing through second power supply 12 increases. If the time from the start of period Tc1 is t, current Is2 flowing through second power supply 12 is expressed as Is2=(Vs1-Vs2) / (L1+L2)×t. If the length of period Tc1 is t_c1, peak value Ip of current Is flowing through first power supply 11 and second power supply 12 is expressed as Ip=(Vs1-Vs2) / (L1+L2)×t_c1.

[0058] During a period Tc2 in the energy recovery state shown in FIG. 6(b), the current Is1 flowing through the first power supply 11 and the current Is2 flowing through the second power supply 12 both decrease to zero. The time required for the current Is1 flowing through the first power supply 11 to reach zero is expressed as Vs1 / L1×Ip. Similarly, the time required for the current Is2 flowing through the second power supply 12 to reach zero is expressed as Vs2 / L2×Ip. Therefore, the time t_c2 required for the current Is1 flowing through the first power supply 11 and the current Is2 flowing through the second power supply 12 to reach zero is the larger of Vs1 / L1×Ip and Vs2 / L2×Ip.

[0059] 7 is performed, 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. Then, by repeating the switching shown in Figure 7, the voltage Vs1 of the first power supply 11 and the voltage Vs2 of the second power supply 12 become equal. 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 and the voltage Vs2 of the second power supply 12 become equal.

[0060] Second voltage balance mode FIG. 8 is a diagram showing current paths when a power supply device according to an embodiment of the present invention is operating in the second voltage balance mode. As with FIGS. 2, 3, and 6, FIG. 8 omits the illustration of voltage detection units 17 and 18, control device 19, and electrical loads. The second voltage balance mode is implemented to equalize voltages Vs1 and Vs2 of first and second power supplies 11 when voltage Vs2 of second power supply 12 is higher than voltage Vs1 of first power supply 11. In the second voltage balance mode, first control unit 19a of control device 19 controls switch circuit 13 to alternate between the energy transfer state shown in FIG. 8(a) and the energy recovery state shown in FIG. 8(b).

[0061] 8(a) is a state in which the first power source 11 and the second power source 12 are connected in parallel, similar to the energy transfer state shown in Fig. 6(a). The energy recovery state shown in Fig. 8(b) is a state in which the first power source 11 is connected across the first reactor 14, and the second power source 12 is connected via the second reactor 15, the first switching element SW1, and the capacitor 16.

[0062] In the energy transfer state shown in Fig. 8(a), electrical energy is transferred from the second power source 12, which has a higher voltage, to the first power source 11. In the energy recovery state shown in Fig. 8(b), in order to reduce the increased peak value Ip of the current flowing through the first power source 11 and the second power source 12, the electrical energy stored in the first reactor 14 and the second reactor 15 is recovered by the first power source 11 and the second power source 12, respectively.

[0063] 8(a), the first control unit 19a performs control (third control) to open the first switching element SW1 and the second switching element SW2 (OFF) and close the third switching element SW3 (ON), thereby establishing the above-described energy transfer state. In the energy transfer state, a current loop LP30 is formed that passes through the first power source 11, the first reactor 14, the third switching element SW3, the second power source 12, the second reactor 15, and the first switching element SW1 in this order. The current loop LP30 is a current path in a state in which the first power source 11 and the second power source 12 are connected in parallel.

[0064] 8(b), the first control unit 19a performs control (second control) to open (OFF) the first switching element SW1 to the third switching element SW3, thereby establishing the above-described energy recovery state. In the energy recovery state, a current loop LP31 is formed, which passes through the first power supply 11, the first reactor 14, the second switching element SW2, and the first switching element SW1 in this order. In addition, a current loop LP32 is also formed, which passes through the second power supply 12, the second reactor 15, the first switching element SW1, and the capacitor 16 in this order. The current loop LP31 is a current path when the first power supply 11 is connected to both ends of the first reactor 14, and the current loop LP32 is a current path when the second power supply 12 is connected via the second reactor 15 and the capacitor 16.

[0065] Fig. 9 is a diagram showing current changes when a power supply device according to one embodiment of the present invention is operating in the second voltage balance mode. In Fig. 9, the period during which the energy transfer state shown in Fig. 8(a) is set is referred to as period Td1, and the period during which the energy recovery state shown in Fig. 8(b) is set is referred to as period Td2. As shown in Fig. 9, the first control unit 19a controls the first switching element SW1 to the third switching element SW3 of the switch circuit 13 to alternately switch between the energy transfer state shown in Fig. 8(a) and the energy recovery state shown in Fig. 8(b).

[0066] 8(a), the current Is2 flowing through the second power supply 12 decreases, while the current Is1 flowing through the first power supply 11 increases. If the time from the start of the period Td1 is t, the current Is1 flowing through the first power supply 11 is expressed as Is1=(Vs2-Vs1) / (L1+L2)×t. If the length of the period Td1 is t_d1, the peak value Ip of the current Is flowing through the first power supply 11 and the second power supply 12 is expressed as Ip=(Vs2-Vs1) / (L1+L2)×t_d1.

[0067] 8(b), during the period Td2 in the energy recovery state, the current Is1 flowing through the first power supply 11 and the current Is2 flowing through the second power supply 12 both decrease to 0. Note that the time t_d2 required for the current Is1 flowing through the first power supply 11 and the current Is2 flowing through the second power supply 12 to both become 0 is the larger of Vs1 / L1×Ip and Vs2 / L2×Ip, similar to the time t_c2 when operating in the first voltage balance mode.

[0068] 9 is performed, 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. Then, by repeating the switching shown in Fig. 9, the voltage Vs1 of the first power supply 11 and the voltage Vs2 of the second power supply 12 become equal. 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 and the voltage Vs2 of the second power supply 12 become equal.

[0069] Fig. 10 is a flowchart showing the processing when voltage balance control is performed in a power supply device according to one embodiment of the present invention. The flowchart shown in Fig. 10 is started, for example, every time a higher-level device (not shown) issues an instruction to control device 19 of power supply device 1 to transition to a parallel connection. Such an instruction to transition is issued, for example, when the vehicle is started.

[0070] 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 equal to or greater than a predetermined reference value (step S11). If the first control unit 19a determines that the voltage difference is not equal to or greater than the reference value, it ends the process shown in Fig. 10. On the other hand, if the first control unit 19a determines that the voltage difference is equal to or greater than the reference value, it determines whether the status instructed by the higher-level device is a parallel state (step S12).

[0071] If the first control unit 19a determines that the status instructed by the higher-level device is not the parallel state, it ends the process shown in Fig. 10. On the other hand, if the first control unit 19a determines that the status instructed by the higher-level 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).

[0072] If the first control unit 19a determines that the first potential difference is not smaller than the threshold (is equal to or greater than the threshold), the first control unit 19a transitions to the first voltage balance mode described with reference to Figures 6 and 7 and performs the first voltage balance control (step S14). Note that the first control unit 19a performs the first voltage balance control in step S14 until it determines in step S13 that the first potential difference is smaller than the threshold. On the other hand, if the first control unit 19a determines that the first potential difference is smaller than the threshold, the first control unit 19a 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 larger than a predetermined threshold (step S15).

[0073] If the first control unit 19a determines that the second potential difference is not smaller than the threshold (is equal to or greater than the threshold), the first control unit 19a transitions to the second voltage balance mode described with reference to FIGS. 8 and 9 and performs the second voltage balance control (step S16). Note that the first control unit 19a performs the second voltage balance control in step S16 until it determines in step S15 that the second potential difference is smaller than the threshold. In contrast, if the first control unit 19a determines that the second potential difference is smaller than the threshold, it performs control to transition to the parallel state shown in FIG. 2(b) (step S17). When the above processing is completed, the first control unit 19a ends the processing shown in FIG. 10.

[0074] As described above, the power supply device 1 of this embodiment includes the first power supply 11 connected between the first node N1 and the second node N2, and the second power supply 12 connected between the third node N3 and the fourth node N4. The power supply device 1 supplies power to the electrical loads (such as the inverter 21, the auxiliary VCU 23, and the inlet 24) connected between the first node N1 and the fourth node N4.

[0075] The power supply device 1 includes a switch circuit 13, a first reactor 14, a second reactor 15, and a control device 19. The switch circuit 13 has 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 the 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 disposed between the first power supply 11 and the first node N1 or the second node N2, and the second reactor 15 is disposed between the second power supply 12 and the third node N3 or the fourth node N4.

[0076] The control device 19 alternately switches between a first state and a second state. In the first state, the first power supply 11 is connected between the first node N1 and the fourth node N4 via the first reactor 14, and the second power supply 12 is connected across the second reactor 15. In the second state, the first power supply 11 is connected across the first reactor 14.

[0077] When the first state is set, the control device 19 controls the second switching element SW2 and the third switching element SW3 of the switch circuit 13 to a closed state and the first switching element SW1 to an open state.When the second state is set, the control device 19 controls the first switching element SW1 and the second switching element SW2 of the switch circuit 13 to a closed state and the third switching element SW3 to an open state.

[0078] This allows high-frequency current to flow through the first power source 11 and the second power source 12 simply by switching between the open and closed states of the multiple switching elements provided in the switch circuit 13, making it possible to heat the first power source 11 and the second power source 12 more efficiently than before without incurring an increase in costs.

[0079] Although the present invention has been described above using the embodiments, the present invention is not limited to these embodiments, and various modifications and substitutions can be made without departing from the spirit and scope of the present invention. For example, in the above-described embodiment, the first reactor 14 is disposed between the first power source 11 and the second node N2, and the second reactor 15 is disposed between the second power source 12 and the third node N3. However, the first reactor 14 may be disposed between the first power source 11 and the first node N1. Similarly, the second reactor 15 may be disposed between the second power source 12 and the fourth node N4.

[0080] Furthermore, the control device 19 can be realized by a computer such as an embedded computer. When the control device 19 is realized by a computer, the functions of each unit of the control device 19 are realized by a program for realizing those functions being executed by a CPU (Central Processing Unit) provided in the computer. In other words, the functions of each unit of the control device 19 are realized by software and hardware resources working together. The control device 19 may also be realized by using hardware such as an FPGA (Field-Programmable Gate Array), an LSI (Large Scale Integration), or an ASIC (Application Specific Integrated Circuit). [Explanation of symbols]

[0081] 1...power supply device, 11...first power supply, 12...second power supply, 13...switch circuit, 14...first reactor, 15...second reactor, 16...capacitor, 17, 18...voltage detection unit, 19...control device, 21...inverter, 22...auxiliary equipment, 23...auxiliary equipment VCU, 24...inlet, N1...first node, N2...second node, N3...third node, N4...fourth node, SW1...first switching element, SW2...second switching element, SW3...third switching element

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; and configured to supply power to an electrical load connected between the first node and the fourth node, a switch circuit including 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 supply and the first node or the second node; a second reactor disposed between the second power supply and the third node or the fourth node; a control device that alternately switches between 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 across both ends of the second reactor by controlling the second switch and the third switch of the switch circuit to a closed state and the first switch to an open state, 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 across both ends of the first reactor by controlling the first switch and the second switch of the switch circuit to a closed state and the third switch to an open state, A power supply device comprising:

2. 2. The power supply device according to claim 1, wherein, when switching between the first state and the second state, the control device temporarily controls the first switch and the third switch to an open state and the second switch to a closed state to establish a third 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 between the first node and the fourth node via the second reactor.

3. a voltage detection unit that detects the voltages of the first power supply and the second power supply, the control device performs balance control by alternately performing a first control for closing the first switch and opening the second switch and the third switch when the voltage of the first power supply is greater than the voltage of the second power supply, and a second control for opening the first switch, the second switch, and the third switch. The power supply device according to claim 1.

4. a voltage detection unit that detects the voltages of the first power supply and the second power supply, the control device performs balance control by alternately performing a third control in which the first switch and the second switch are in an open state and the third switch is in a closed state, and a second control in which the first switch, the second switch, and the third switch are in an open state, when the voltage of the second power source is greater than the voltage of the first power source. The power supply device according to claim 1.

5. the control device is capable of switching between a parallel state in which the first power supply and the second power supply are connected in parallel between the first node and the fourth node by controlling the first switch and the third switch to a closed state and the second switch to an open state, and a series state in which the first power supply and the second power supply are connected in series between the first node and the fourth node by controlling the first switch and the third switch to an open state and the second switch to a closed state, performing the balance control when a 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; 5. The power supply device according to claim 3 or 4.

6. A control method for a power supply apparatus 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; and the power supply apparatus supplies power to an electrical load connected between the first node and the fourth node, the control method comprising: The power supply device includes 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 supply and the first node or the second node; a second reactor arranged between the second power supply and the third node or the fourth node, a step of alternately switching between a first state in which the second switch and the third switch of the switch circuit are controlled to a closed state and the first switch is controlled to an open state, so that 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 across both ends of the second reactor, and a second state in which the first switch and the second switch of the switch circuit are controlled to a closed state and the third switch is controlled to an open state, so that 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 across both ends of the first reactor. A method for controlling a power supply.

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