Power supply system

Abstract

This system suppresses frequent switching between series and disconnected connections of the two batteries when charging them using power from an onboard generator. [Solution] The power supply system comprises a first battery, a second battery having the same configuration as the first battery, an auxiliary device connected to a low-voltage power line connected to an auxiliary battery, a series-parallel switching circuit capable of switching between series and parallel connections of the first and second batteries by switching on and off multiple relays, and a power converter connected to the series-parallel switching circuit and the low-voltage power line. When charging the first and second batteries with power from a power generator, the first and second batteries are charged in series when the power consumption of the auxiliary device is above a predetermined power, and the first and second batteries are charged in non-series connection when the power consumption of the auxiliary device is below the predetermined power.

Description

Technical Field

[0001] The present disclosure relates to a power supply system, and more particularly to an in-vehicle power supply system including two batteries capable of charging and discharging by series connection and charging and discharging by parallel connection.

Background Art

[0002] Conventionally, as this type of power supply system, a series-parallel battery system in which a plurality of batteries can be switched between series and parallel has been proposed (see, for example, Patent Document 1). In this system, the connection method at the start of charging is selected based on the temperature and SOC of the power supply device, and the charging current for the parallel connection method is controlled using an upper limit value larger than the upper limit value of the charging current for the series connection method input to the power supply device.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] When charging two batteries with power from on-board solar panels, the power required to drive the auxiliary equipment may frequently exceed the power generated by the solar panels, depending on the operating status of the auxiliary equipment and the weather. When the power required to drive the auxiliary equipment exceeds the power generated by the solar panels, a DC / DC converter is used to reduce the voltage of the power from the two batteries and supply it to the auxiliary equipment. However, to simplify the configuration of the DC / DC converter, it is often designed to supply power to the auxiliary equipment by reducing the voltage of the two batteries when they are connected in series. In this case, if the power required to drive the auxiliary equipment exceeds the power generated by the solar panels while charging the two batteries connected in parallel or only one of them with power generated by the solar panels, it becomes necessary to switch the two batteries to a series connection in order to reduce the voltage of the power from the two batteries and supply it to the auxiliary equipment using the DC / DC converter. When the power required to drive the auxiliary equipment frequently exceeds the power generated by the solar panels, the parallel connection and series connection of the two batteries will be switched periodically.

[0005] The primary purpose of the power supply system disclosed herein is to suppress frequent switching between series and non-series connections of two batteries when charging two batteries, which can be connected in series or not, using power from an onboard generator. [Means for solving the problem]

[0006] The power supply system disclosed herein employs the following measures to achieve the primary objectives described above.

[0007] The power supply system disclosed herein comprises: a first battery; a second battery having the same configuration as the first battery; an auxiliary battery having a voltage lower than the rated voltage of the first battery; an auxiliary device connected to a low-voltage power line connected to the auxiliary battery; an on-board power generator connected to the low-voltage power line; a series-parallel switching circuit having a plurality of relays, which can switch between a series connection of the first battery and the second battery and a parallel connection of the first battery and the second battery by switching the plurality of relays on and off; a power converter connected to the series-parallel switching circuit and the low-voltage power line; and a control device that drives and controls the plurality of relays of the series-parallel switching circuit and controls the power converter. The control device is characterized in that, when charging the first battery and the second battery with power from the power generator, if the power consumption of the auxiliary equipment is greater than or equal to a predetermined power, it performs series connection charging control, which controls the plurality of relays and the power converter so that the first battery and the second battery are connected in series and charged with power from the power generator; and if the power consumption of the auxiliary equipment is less than the predetermined power, it performs non-series connection charging control, which controls the plurality of relays and the power converter so that the first battery and the second battery are charged with power from the power generator with the series connection between the first battery and the second battery disconnected.

[0008] The power supply system disclosed herein is mounted in a vehicle and comprises: a first battery; a second battery having the same configuration as the first battery; an auxiliary battery with a voltage lower than the rated voltage of the first battery; an auxiliary device connected to a low-voltage power line connected to the auxiliary battery; a vehicle-mounted power generator connected to the low-voltage power line; a series-parallel switching circuit having multiple relays, which can switch between a series connection of the first and second batteries and a parallel connection of the first and second batteries by switching the multiple relays on and off; a power converter connected to the series-parallel switching circuit and also connected to a low-voltage power line; and a control device that drives and controls the multiple relays of the series-parallel switching circuit and controls the power converter. When the control device charges the first and second batteries with power from the power generator, if the power consumption of the auxiliary device exceeds a predetermined power, it performs series connection charging control, which controls the multiple relays and controls the power converter so that the first and second batteries are connected in series and charged with power from the power generator. On the other hand, when the power consumption of the auxiliary equipment is less than a predetermined power, non-series connection charging control is performed, which controls multiple relays and the power converter so that the first and second batteries are charged by power from the generator with the series connection between the first and second batteries disconnected. By setting a relatively low power generation power from the generator as the predetermined power, it is possible to suppress frequent switching from non-series connection to series connection between the first and second batteries, which would occur if the power consumption of the auxiliary equipment frequently exceeded the power generation power from the generator.

[0009] In the power supply system of this disclosure, the control device may perform, as the non-series connection charging control, a first battery charging process which alternately performs the following: a first battery charging process which turns on and off the plurality of relays to charge only the first battery with power from the power generator, thereby charging only the first battery; and a storage ratio equalization process which turns on and off the plurality of relays to charge the second battery with power from the first battery, thereby equalizing the storage ratio of the first battery and the storage ratio of the second battery. Since the equalization of the storage ratio of the first battery and the storage ratio of the second battery is performed in a relatively short time, the first battery and the second battery can be charged in the same short time as the time it takes to charge only the first battery with power from the power generator or external power source, thereby improving charging efficiency. In this case, the control device may supply power from the power generator or external power source to the auxiliary battery or auxiliary battery while the storage ratio equalization process is being performed. This allows the power from the power generator to be effectively utilized even while the storage ratio equalization process is being performed.

[0010] In the power supply system of the present disclosure, the series-parallel switching circuit includes a series connection line connecting the negative terminal of the first battery and the positive terminal of the second battery, a series connection relay attached to the series connection line, a positive bus connected to the positive terminal of the first battery, a negative bus connected to the negative terminal of the second battery, an inverter connected to the positive bus and the negative bus, a three-phase AC motor driven by the inverter, a positive-side relay attached to the positive bus, a negative-side relay attached to the negative bus, and the series connection relay on the series connection line. The power converter may be configured to include a first parallel connection line connecting the first battery side and the negative busbar, a first parallel connection relay attached to the first parallel connection line, a second parallel connection line connecting the positive terminal of the second battery and the neutral point of the three-phase AC motor, and a second parallel connection relay and a third parallel connection relay attached to the second parallel connection line in order from the second battery side, wherein the power converter is connected via charging relays from the positive side relay of the positive busbar to the first battery side and from the negative side relay of the negative busbar to the second battery side. [Brief explanation of the drawing]

[0011] [Figure 1] This is a schematic diagram showing the configuration of a power supply system 20 in one embodiment of the present disclosure. [Figure 2] This flowchart shows an example of a solar charging process performed by the electronic control unit 60. [Figure 3] This flowchart shows an example of charge equalization control performed by the electronic control unit 60. [Figure 4] This is an explanatory diagram showing an example of a circuit for charging the first battery 26a and the second battery 26b when they are connected in series. [Figure 5] This is an explanatory diagram showing an example of a circuit when charging only the first battery 26a. [Figure 6] This is an explanatory diagram showing an example of a circuit used in the equalization process. [Modes for carrying out the invention]

[0012] Next, embodiments for implementing this disclosure will be described. Figure 1 is a schematic diagram showing the configuration of an in-vehicle power supply system 20 as one embodiment of this disclosure. The power supply system 20 of this embodiment is mounted on an electric vehicle as a device that exchanges power between a battery 26 and an inverter 24 that drives a motor 22, and charges and discharges the battery 26 using the motor 22 and inverter 24 as needed. The power supply system 20 comprises a battery 26, a motor 22, an inverter 24, a main power supply circuit 30, an AC charging circuit 40, a DC charging circuit 50, and an electronic control unit 60. The motor 22 functions as an electric motor for driving the electric vehicle.

[0013] The motor 22 is configured as a well-known three-phase AC motor, comprising, for example, a rotor with permanent magnets attached to its outer surface and a stator around which three-phase coils are wound. The inverter 24 is composed of six transistors T1 to T6 as switching elements and six diodes D1 to D6 connected in parallel to the transistors T1 to T6 in the opposite direction. The transistors T1 to T6 are arranged in pairs such that the inverter 24 is on the source side and the sink side with respect to the positive bus 31B and negative bus 31G of the battery 26. Each of the three-phase coils (U-phase, V-phase, W-phase) of the motor 22 is connected to each of the connection points between the pairs of transistors T1 to T6. The inverter 24 rotates the motor 22 by controlling the ratio of the on-times of the pairs of transistors T1 to T6 while a voltage is acting between the positive bus 31B and the negative bus 31G, thereby forming a rotating magnetic field in the three-phase coils. A first smoothing capacitor 32 is installed between the positive busbar 31B and the negative busbar 31G.

[0014] The battery 26 comprises a first battery 26a and a second battery 26b configured similarly to the first battery 26a. The first battery 26a and the second battery 26b are configured as, for example, lithium-ion secondary batteries or nickel-metal hydride secondary batteries. The positive terminal of the first battery 26a is connected to the positive busbar 31B, and the negative terminal of the second battery 26b is connected to the negative busbar 31G. The negative terminal of the first battery 26a is connected to the positive terminal of the second battery 26b by a series power line 35 to which a relay DCRNN, which is included in the configuration of the main power circuit 30, is attached. Therefore, by turning on the relay DCRNN, the first battery 26a and the second battery 26b function as a single battery connected in series.

[0015] The main power supply circuit 30 includes a positive busbar 31B, a negative busbar 31G, a series power line 35, a first parallel power line 36 connecting the negative terminal of the first battery 26a to the negative busbar 31G, and a second parallel power line 37 connecting the positive terminal of the second battery 26b to the neutral point of the motor 22. A positive-side relay SMRB is attached to the positive busbar 31B, and a negative-side relay SMRG is attached to the negative busbar 31G. In addition, a pre-charge circuit consisting of a pre-charge relay SMRP and a resistor R is provided in parallel with the negative-side relay SMRG on the negative busbar 31G. These positive-side relay SMRB, negative-side relay SMRG, and pre-charge circuit constitute the system main relay. Specifically, when the first battery 26a and the second battery 26b are connected in series, the positive side relay SMRB is turned on and the pre-charge relay SMRP is turned on to charge the first capacitor 32. When the charging of the first capacitor 32 is complete, the negative side relay SMRG is turned on and the pre-charge relay SMP is turned off, thereby enabling power from the battery 26, consisting of the first battery 26a and the second battery 26b connected in series, to be supplied to the inverter 24, or conversely, the battery 26 to be charged by regenerative power from the motor 22.

[0016] A relay DCRNG is attached to the first parallel power line 36. A relay DCRNB is attached to the second battery 26b side of the second parallel power line 37, and a relay DCRN is attached to the neutral point side of the motor 22. A second capacitor 38 is attached between relay DCRNB and relay DCRN on the second parallel power line 37 and to the negative busbar 31G.

[0017] The AC charging circuit 40 includes an AC charging power line 41 connected to a positive bus 31B and a negative bus 31G, an on-board charger (OBC) 43 connected to the AC charging power line 41 via a filter 42, an AC charging connector 45 connected to the on-board charger 43 by a power line 44, a DC / DC converter 46 connected to the AC charging power line 41 in parallel with the on-board charger 43 via a filter 42, and an auxiliary battery, accessories 48a, and a solar panel 49 connected to the DC / DC converter 46 by a power line 47. A relay SSRB is attached to the positive side line of the AC charging power line 41, and a relay SSRG is attached to the negative side line.

[0018] The DC charging circuit 50 includes a DC charging power line 51 connected to a positive bus 31B and a negative bus 31G, and a DC charging connector 55 connected to the DC charging power line 51. A relay DCRB is attached to the positive side line of the DC charging power line 51, and a relay DCRG is attached to the negative side line.

[0019] The electronic control unit 60 is configured as a microcomputer centered around a CPU, although not shown in the figure. Signals from various sensors are input to the electronic control unit 60. Examples of the various sensors include a voltage sensor 33 that detects the voltage VH between the terminals of the first capacitor 32, a voltage sensor 39 that detects the voltage VD between the terminals of the second capacitor 38, a current sensor 31a that detects the current Ib1 flowing through the first battery 26a, a current sensor 37a that detects the current Id flowing through the second parallel power line 37, a phase current sensor (not shown) that detects the phase currents Iu, Iv, Iw flowing through the three phases of the motor 22, a voltage sensor (not shown) that detects the voltage Vb1 between the terminals of the first battery 26a, and a voltage sensor (not shown) that detects the voltage Vb2 between the terminals of the second battery 26b. Since the electronic control unit 60 also functions as a control device that drives the motor 22, drive commands and the like are also input. When the power system 20 is mounted on a vehicle and the motor 22 is used as a traveling motor, the accelerator opening and vehicle speed may be input to the electronic control unit 60, and the electronic control unit 60 may generate a torque command for the motor 22.

[0020] Drive control signals to each relay and switching control signals to the inverter 24 are output from the electronic control unit 60. Examples of the various relays include the positive-side relay SMRB, the negative-side relay SMRG, the precharge relay SMRP, the relay DCRNN, the relay DCRNG, the relay DCRNB, the relay DCRN, the relay SSRB, the relay SSRB, the relay DCRB, and the relay DCRG.

[0021] When the power system 20 of the embodiment configured in this way drives the motor 22 as a traveling motor and is running, the positive-side relay SMRB, the negative-side relay SMRG, the relay SSRB, the relay SSRG, and the relay DCRNN are turned on, and the relays DCRB, DCRG, DCRN, DCRB, and DCRG are turned off. The six transistors T1 to T6 of the inverter 24 are switched and controlled by PWM control or the like based on a torque command corresponding to the accelerator opening and vehicle speed V.

[0022] Next, the operation when charging the battery 26 with the electric power generated by the solar panel 49 will be described. FIG. 2 is a flowchart showing an example of the solar charging process executed by the electronic control unit 60 when charging the battery 26 with the electric power from the solar panel 49, and FIG. 3 is a flowchart showing an example of the charge equalization control executed by the electronic control unit 60. The charge equalization control will be described later.

[0023] When the solar charging process is executed, the electronic control unit 60 first determines whether it is charging the battery 26 with the electric power from the solar panel 49 (step S100). When it is determined that it is not charging the battery 26 with the electric power from the solar panel 49, for example, when an external DC power source is connected to the DC charging connector 55 and the battery 26 is being charged with the electric power from the external DC power source, since it is outside the scope of this process, this process is terminated.

[0024] In step S100, if it is determined that the battery 26 is being charged by power from the solar panel 49, it is determined whether the load (power consumption) of the auxiliary equipment 48a is less than a predetermined power (step S110). The predetermined power can be, for example, the power that can be generated by the solar panel 49 on a cloudy day. If it is determined that the load (power consumption) of the auxiliary equipment 48a is equal to or greater than the predetermined power, the first battery 26a and the second battery 26b are charged by series connection charging control (step S140), and this process is terminated. As shown in Figure 4, charging of the first battery 26a and the second battery 26b by series connection charging control is performed by turning on relays SSRB, SSRG, and DCRNN, while turning off the positive side relay SMRB, negative side relay SMRG, relay DCRB, relay DCRG, relay DCRN, relay DCRNB, relay DCRB, and relay DCRG, thereby forming a circuit that returns from filter 42 via relay SSRB to the positive bus 31B, the first battery 26a, the series power line 35, relay DCRNN, the second battery 26b, the negative bus 31G, and relay SSRG, and returning to filter 42. While the battery 26 is being charged by the power from the solar panel 49, even if the power generated by the solar panel 49 decreases or the load (power consumption) of the auxiliary equipment 48a increases and the load (power consumption) of the auxiliary equipment 48a becomes greater than the power generated by the solar panel 49, the power from the battery 26 can be stepped down and supplied to the auxiliary equipment 48a without driving a relay, simply by changing the switching control of the DC / DC converter 46.

[0025] If it is determined in step S110 that the load (power consumption) of the auxiliary equipment 48a is less than a predetermined power, the loss L1 when series connection charging control is performed to charge the first battery 26a and the second battery 26b in series is calculated, and the loss L2 when charge equalization control is performed to charge the first battery 26a and the second battery 26b by alternately repeating a first battery charging process that charges only the first battery 26a and an equalization process that equalizes the charge level SOC1 of the first battery 26a and the charge level SOC1 of the second battery 26b (step S120). The loss L1 is the loss when charging the battery 236 using a circuit that returns from the filter 42 via relay SSRB to positive bus 31B, first battery 26a, relay DCRNN, second battery 26b, negative bus 31G, relay SSRG and back to the filter 42. Charge equalization control and its loss L2 will be described later.

[0026] Next, the loss L1 when series connection charging control is performed is compared with the loss L2 when charge equalization control is performed (step S130). If it is determined that the loss L1 when series connection charging control is performed is less than the loss L2 when charge equalization control is performed, the series connection charging control is performed (step S140) and the process ends. On the other hand, if it is determined in step S130 that the loss L1 when series connection charging control is performed is greater than or equal to the loss L2 when charge equalization control is performed, the charge equalization control is performed (step S150) and the process ends.

[0027] In charge equalization control, as shown in the flowchart of Figure 3, the electronic control unit 60 first charges only the first battery 26a (step S200). This charging of only the first battery 26a is performed by turning on relays SSRB, SSRG, and DCRNG, while turning off the positive side relay SMRB, negative side relay SMRG, DCRNN, DCRB, DCRG, DCRN, DCRNB, DCRB, and DCRG, as shown in the explanatory diagram of Figure 5. This creates a circuit that returns from filter 42 to filter 42 via relay SSRB, positive bus 31B, first battery 26a, relay DCRNG, first parallel power line 36, negative bus 31G, and relay SSRG.

[0028] Next, it is determined whether the difference between the charge storage ratio SOC1 of the first battery 26a and the charge storage ratio SOC1 of the second battery 26b (SOC1-SOC2) is greater than or equal to the threshold Sref (step S210). If it is determined that the difference between the charge storage ratio SOC1 of the first battery 26a and the charge storage ratio SOC1 of the second battery 26b (SOC1-SOC2) is greater than or equal to the threshold Sref, a process is performed to equalize the charge storage ratio SOC1 of the first battery 26a and the charge storage ratio SOC1 of the second battery 26b (step S220), and during the equalization process, power from the solar panel 49 is supplied to the auxiliary battery 48 and auxiliary 48a (step S230). As shown in the explanatory diagram in Figure 6, the equalization process is performed by turning on the positive side relays SMRB, DCRNG, DCRN, and DCRNB, while turning off the relays SSRB, SSRG, positive side relay SMRB, negative side relay SMRG, DCRNN, DCRB, and DCRG, and further turning on one, two, or all of the transistors T1, T2, and T3 of the inverter 24, thereby forming a circuit from the positive terminal of the first battery 26a to the positive bus 31B, positive side relay SMRB, transistors T1, T2, and T3 of the inverter 24, motor 22, second parallel power line 37, relay DCRN, relay DCRNB, second battery 26b, negative bus 31G, first parallel power line 36, relay DCRNG, and the negative terminal of the first battery 26a. Power from the solar panel 49 can be supplied to the auxiliary battery 48 and auxiliary 48a via the power line 47. If, in step S210, it is determined that the difference between the charge storage ratio SOC1 of the first battery 26a and the charge storage ratio SOC1 of the second battery 26b (SOC1-SOC2) is less than the threshold Sref, then the equalization process is not performed.

[0029] Next, it is determined whether or not charging of battery 26 is complete (step S240). Completion of battery 26 charging includes when the first battery 26a and the second battery 26b are fully charged, or when preparations for starting driving are made. If it is determined that charging of battery 26 is not complete, the process returns to step S200, which charges only the first battery 26a. The process from step S200 to step S240 alternately repeats the following processes until it is determined that charging is complete: charging only the first battery 26a until the difference between the charge level SOC1 of the first battery 26a and the charge level SOC2 of the second battery 26b is equal to or greater than the threshold Sref; equalizing the charge level SOC1 of the first battery 26a and the charge level SOC2 of the second battery 26b; and supplying power from the solar panel 49 to the auxiliary battery 48 and auxiliary 48a during the equalization process. Furthermore, the charge equalization control and its loss L2 are losses incurred when alternating between the process of charging only the first battery 26a and the process of equalizing the charge level SOC1 of the first battery 26a and the charge level SOC2 of the second battery 26b.

[0030] When it is determined in step S230 that charging is complete, an equalization process is performed (step S250) to terminate this process. The equalization process is performed at the end in order to make the charge level SOC1 of the first battery 26a and the charge level SOC2 of the second battery 26b the same.

[0031] While charge equalization control is being performed, the power generated by the solar panel 49 may decrease or the load (power consumption) of the auxiliary equipment 48a may increase, resulting in the load (power consumption) of auxiliary equipment 48a becoming greater than the power generated by the solar panel 49. In such cases, the first battery 26a and the second battery 26b may be connected in series to reduce the voltage of the battery 26 and supply it to the auxiliary equipment 48a. However, since the power consumption of auxiliary equipment 48a is basically below a predetermined power, this occurs infrequently.

[0032] In the power supply system 20 of the embodiment described above, when charging the battery 26 with power from the solar panel 49, if the load (power consumption) of the auxiliary equipment 48a is greater than or equal to a predetermined power, the first battery 26a and the second battery 26b are charged by series connection charging control. As a result, even if the power generated by the solar panel 49 decreases or the load (power consumption) of the auxiliary equipment 48a increases and the load (power consumption) of the auxiliary equipment 48a becomes greater than the power generated by the solar panel 49, the power of the battery 26 can be stepped down and supplied to the auxiliary equipment 48a without driving a relay, simply by changing the switching control of the DC / DC converter 46. As a result, it is possible to suppress frequent switching between series connection and non-series connection of the first battery 26a and the second battery 26b when charging the first battery 26a and the second battery 26b.

[0033] In the power supply system 20 of this embodiment, when charging the battery 26 with power from the solar panel 49, if the load (power consumption) of the auxiliary equipment 48a is less than a predetermined power, and the loss L1 when executing series connection charging control is greater than or equal to the loss L2 when executing charge equalization control, then charge equalization control is executed to charge the battery 26. Compared to the case where alternating charging control is performed, which alternately charges only the first battery 26a and only the second battery 26b, the charging time can be shortened and the charging efficiency can be increased. Moreover, by supplying power from the solar panel 49 to the auxiliary battery 48 and auxiliary equipment 48a during the equalization process, the power from the solar panel 49 can be utilized more effectively.

[0034] In the power supply system 20 of this embodiment, when charging the battery 26 with power from the solar panel 49, if the load (power consumption) of the auxiliary equipment 48a is less than a predetermined power, the system selects the smaller of the loss L1 when series connection charging control is performed and the loss L2 when charge equalization control is performed to charge the battery 26. This makes it possible to further increase the charging efficiency.

[0035] The correspondence between the main elements of the embodiment and the main elements of the invention described in the section on means for solving the problem will be explained. In the embodiment, the first battery 26a corresponds to the "first battery", the second battery 26b corresponds to the "second battery", the auxiliary battery 48 corresponds to the "auxiliary battery", the auxiliary 48a corresponds to the "auxiliary", the solar panel 49 corresponds to the "power generation device", the main power supply circuit 30 corresponds to the "series-parallel switching circuit", the DC / DC converter 46 corresponds to the "voltage converter", the electronic control unit 60 corresponds to the "control device", and the power supply system 20 corresponds to the "power supply system".

[0036] Furthermore, the correspondence between the main elements of the embodiment and the main elements of the invention described in the section on means for solving the problem is merely an example to specifically explain the form in which the embodiment implements the invention described in the section on means for solving the problem, and does not limit the elements of the invention described in the section on means for solving the problem. In other words, the interpretation of the invention described in the section on means for solving the problem should be based on the description in that section, and the embodiment is merely one specific example of the invention described in the section on means for solving the problem.

[0037] Although the present disclosure has been described above using embodiments, the present disclosure is not limited in any way to these embodiments, and can of course be implemented in various forms without departing from the gist of the present disclosure. [Industrial applicability]

[0038] This disclosure can be used in industries such as the manufacturing of power supply systems. [Explanation of Symbols]

[0039] 20 Power system, 22 Motor, 24 Inverter, 26 Battery, 26a First battery, 26b Second battery, 30 Main power circuit, 31a Current sensor, 31B Blue busbar, 31G Negative busbar, 32 First capacitor, 33 Voltage sensor, 35 Series power line, 36 First parallel power line, 37 Second parallel power line, 37a Current sensor, 38 Second capacitor, 39 Voltage sensor, 40 AC charging circuit, 41 AC charging power line, 42 Filter, 43 Onboard charger, 44 Power line, 45 AC charging connector, 46 DC / DC converter, 47 Power line, 48 Auxiliary battery, 48a Auxiliary, 49 Solar panel, 50 DC charging circuit, 51 DC charging power line, 55 DC charging connector, 60 Electronic control unit.

Claims

1. The first battery and A second battery having the same configuration as the first battery, An auxiliary battery with a voltage lower than the rated voltage of the first battery, The auxiliary equipment is connected to the low-voltage power line connected to the aforementioned auxiliary battery, A vehicle-mounted power generator connected to the aforementioned low-voltage power line, A series-parallel switching circuit having multiple relays, which can switch between a series connection of the first battery and the second battery and a parallel connection of the first battery and the second battery by turning the multiple relays on and off, A power converter connected to the series-parallel switching circuit and also connected to the low-voltage power line, A control device that drives and controls the plurality of relays in the series-parallel switching circuit and controls the power converter, An in-vehicle power supply system equipped with, When the control device charges the first battery and the second battery with power from the power generator, When the power consumption of the auxiliary equipment exceeds a predetermined power, the series connection charging control is performed, which involves connecting the first battery and the second battery in series and controlling the multiple relays and the power converter so that the first battery and the second battery are charged by the power from the generator. When the power consumption of the auxiliary equipment is less than the predetermined power, the series connection between the first battery and the second battery is disconnected, and non-series connection charging control is performed by controlling the plurality of relays and the power converter so that the first battery and the second battery are charged by power from the generator. A power supply system characterized by the following features.

2. A power supply system according to claim 1, The control device performs, as the non-series connection charging control, a first battery charging process which alternately performs the following: a first battery charging process which charges only the first battery by turning on and off the plurality of relays so that only the first battery is charged by the power from the power generator; and a storage ratio equalization process which equalizes the storage ratio of the first battery and the storage ratio of the second battery by turning on and off the plurality of relays so that the second battery is charged by the power from the first battery so that the second battery is charged by the power from the first battery. Power supply system.

3. The power supply system according to claim 2, While the control device is performing the energy storage ratio equalization process, it supplies power from the power generator or the external power source to the auxiliary equipment or the auxiliary battery. Power supply system.

4. A power supply system according to any one of claims 1 to 3, The series-parallel switching circuit comprises a series connection line connecting the negative terminal of the first battery and the positive terminal of the second battery, a series connection relay attached to the series connection line, a positive bus connected to the positive terminal of the first battery, a negative bus connected to the negative terminal of the second battery, an inverter connected to the positive bus and the negative bus, a three-phase AC motor driven by the inverter, a positive-side relay attached to the positive bus, a negative-side relay attached to the negative bus, a first parallel connection line connecting the first battery side and the negative bus from the series connection relay on the series connection line, a first parallel connection relay attached to the first parallel connection line, a second parallel connection line connecting the positive terminal of the second battery and the neutral point of the three-phase AC motor, and a second parallel connection relay and a third parallel connection relay attached to the second parallel connection line in order from the second battery side. The power converter is connected via charging relays to the first battery side of the positive busbar's positive side relay and to the second battery side of the negative busbar's negative side relay. Power supply system.

Images