Power supply system

Abstract

To provide a power source system that can be prevented from increasing in size.SOLUTION: A power source system 1 includes: a distribution line L1 supplied with DC power from an external power source; a battery 2 connected to the distribution line L1; DC / DC converters 5, 6 that convert the DC power supplied to the distribution line L1 into different voltage values for output to a load group 50; a filter unit 7 having a first cutoff frequency and connected to the distribution line L1 and the DC / DC converter 5; a filter unit 8 having a second cutoff frequency higher than the first cutoff frequency and connected to the distribution line L1 and the DC / DC converter 6; and a control unit 10 that controls the DC / DC converters 5, 6. The control unit 10 controls the DC / DC converter 5 in a case where the DC power is supplied to the distribution line L1 from the external power source and it is necessary to supply the DC power to the load group 50.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] This disclosure relates to a power supply system.

Background Art

[0002] There is known a vehicle equipped with a charging device capable of charging an in-vehicle battery with electric power supplied from an external power source. Patent Document 1 describes an electric vehicle including a high-voltage battery, a low-voltage battery, and a DC / DC converter provided between the high-voltage battery and the low-voltage battery.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The required noise level varies depending on the operating mode of the vehicle. In order to meet these requirements, a noise filter is mounted on the DC / DC converter. However, as the current of the DC / DC converter increases, the noise filter has become larger.

[0005] This disclosure describes a power supply system capable of suppressing an increase in size.

Means for Solving the Problems

[0006] A power supply system relating to one aspect of this disclosure is a power supply system mounted on a vehicle, comprising: wiring to which DC power is supplied from an external power source; a DC power supply connected to the wiring; a first DC / DC converter that converts the DC power supplied to the wiring into different voltage values ​​and outputs them to a group of loads including at least one load; a first filter unit having a first cutoff frequency and connected to the wiring and the first DC / DC converter; a second DC / DC converter that converts the DC power supplied to the wiring into different voltage values ​​and outputs them to a group of loads; a second filter unit having a second cutoff frequency higher than the first cutoff frequency and connected to the wiring and the second DC / DC converter; and a control unit that controls the first DC / DC converter and the second DC / DC converter. The control unit controls the first DC / DC converter when DC power is supplied to the wiring from an external power source and it is necessary to supply DC power to a group of loads.

[0007] In this power supply system, a wiring to which DC power is supplied from an external power source and a first DC / DC converter that converts the DC power supplied to the wiring to a different voltage value are electrically connected via a first filter section having a first cutoff frequency. The wiring and a second DC / DC converter that converts the DC power supplied to the wiring to a different voltage value are electrically connected via a second filter section having a second cutoff frequency higher than the first cutoff frequency. When DC power is supplied to the wiring from an external power source and it is necessary to supply DC power to a load group, the first DC / DC converter is controlled. As a result, the wiring and the first DC / DC converter are electrically connected via the first filter section, which can reduce noise in the lower frequency band than the second filter section, thus suppressing the transmission of low-frequency noise to the external power source. On the other hand, when the vehicle is in motion, the first and second DC / DC converters are not electrically connected to an external power supply. Therefore, there is no need to suppress low-frequency noise that can be suppressed by the first filter but not by the second filter, and the second DC / DC converter can be driven. As a result, when a large amount of DC power is required by the load group, driving the first and second DC / DC converters makes it possible to supply a large amount of DC power to the load group. Furthermore, although the second filter can only suppress noise in a higher frequency band than the first filter, it has a smaller circuit size than the first filter. Therefore, it is possible to provide an inexpensive power supply system that can supply a large amount of power to the load group and suppress the transmission of low-frequency noise to the external power supply, thereby suppressing the need for a larger power supply system.

[0008] In some embodiments, the first and second cutoff frequencies may be set such that the voltage fluctuation range at the output terminal of the first DC / DC converter and the voltage fluctuation range at the output terminal of the second DC / DC converter fall within the allowable range of the input voltage of the load group. When the first and second DC / DC converters are operated simultaneously, noise generated by the other DC / DC converter is input to one DC / DC converter, and this noise can cause the voltage value at the output terminal to fluctuate. With the above configuration, since the voltage fluctuation range at the output terminal of the first DC / DC converter and the voltage fluctuation range at the output terminal of the second DC / DC converter fall within the allowable range of the input voltage of the load group, stable power can be supplied to the load group.

[0009] In some embodiments, the first and second cutoff frequencies may be set such that the resonant frequency of the first filter when a signal passes through the first filter from the first DC / DC converter toward the wiring does not coincide with the resonant frequency of the second filter when a signal passes through the second filter from the wiring toward the second DC / DC converter, and the resonant frequency of the first filter when a signal passes through the first filter from the wiring toward the first DC / DC converter does not coincide with the resonant frequency of the second filter when a signal passes through the second filter from the second DC / DC converter toward the wiring.

[0010] Noise generated in the first DC / DC converter may be transmitted through a path sequentially passing through the first filter section, wiring, second filter section, and second DC / DC converter. In this case, if the resonant frequency of the first filter section when the signal passes through the first filter section from the first DC / DC converter towards the wiring matches the resonant frequency of the second filter section when the signal passes through the second filter section from the wiring towards the second DC / DC converter, resonance may cause the voltage fluctuation range at the output terminal of the second DC / DC converter to exceed the allowable range of the input voltage of the load group. Similarly, noise generated in the second DC / DC converter may be transmitted through a path sequentially passing through the second filter section, wiring, first filter section, and first DC / DC converter. In this case, if the resonant frequency of the first filter section when the signal passes through the first filter section from the wiring towards the first DC / DC converter coincides with the resonant frequency of the second filter section when the signal passes through the second filter section from the second DC / DC converter towards the wiring, resonance may cause the voltage fluctuation range at the output terminal of the first DC / DC converter to exceed the allowable range of the input voltage of the load group. With the above configuration, since the resonant frequencies of the first filter section and the second filter section in each path do not coincide, it is possible to suppress the voltage fluctuation range at the output terminal of the first DC / DC converter and the voltage fluctuation range at the output terminal of the second DC / DC converter from exceeding the allowable range of the input voltage of the load group. [Effects of the Invention]

[0011] According to this disclosure, it is possible to suppress the increase in size of the power supply system. [Brief explanation of the drawing]

[0012] [Figure 1] Figure 1 is a schematic diagram of a power supply system according to one embodiment. [Figure 2]Figure 2(a) shows the gain characteristics of the filter circuit 71 when a signal passes through the filter circuit 71 from the DC / DC converter 5 toward the wiring L1. Figure 2(b) shows the gain characteristics of the filter circuit 71 when a signal passes through the filter circuit 71 from the wiring L1 toward the DC / DC converter 5. [Figure 3] Figure 3(a) shows the gain characteristics of the filter circuit 81 when a signal passes through the filter circuit 81 from the DC / DC converter 6 toward the wiring L1. Figure 3(b) shows the gain characteristics of the filter circuit 81 when a signal passes through the filter circuit 81 from the wiring L1 toward the DC / DC converter 6. [Figure 4] Figure 4 is a flowchart showing an example of switching control performed by the control unit shown in Figure 1. [Figure 5] Figure 5 is a diagram illustrating an example of the operation of a power supply system. [Figure 6] Figure 6 is a diagram illustrating another example of the operation of the power supply system. [Figure 7] Figure 7 illustrates yet another example of the operation of a power supply system. [Modes for carrying out the invention]

[0013] A power supply system according to one embodiment will be described in detail below with reference to the attached drawings. In the description of the drawings, the same reference numerals are used for the same or equivalent elements, and redundant explanations are omitted.

[0014] The schematic configuration of a power supply system according to one embodiment will be described with reference to Figure 1. Figure 1 is a schematic diagram of the power supply system according to one embodiment. The power supply system 1 shown in Figure 1 is mounted on a vehicle V and supplies DC power to a group of loads 50 mounted on the vehicle V. Examples of the vehicle V include a forklift, a hybrid vehicle, and an electric vehicle. The group of loads 50 includes at least one load 51. Examples of the load 51 include a navigation system and an in-car radio.

[0015] The power supply system 1 includes a battery 2 (DC power supply), an in-vehicle charger 3, a switch 4, a DC / DC converter 5 (first DC / DC converter), a DC / DC converter 6 (second DC / DC converter), a filter section 7 (first filter section), a filter section 8 (second filter section), a control section 10, a connector CN1, a connector CN2, a wiring L1, and a wiring L2.

[0016] The connector CN1 is a connector for connecting a DC charger (external power supply) that outputs DC power. The DC charger supplies DC power to the wiring L1 via the connector CN1. The connector CN2 is a connector for connecting an AC charger (external power supply) that outputs AC power, and is connected to the in-vehicle charger 3. The DC power output from the DC charger is supplied to the wiring L1. Also, the DC power output from the in-vehicle charger 3 is supplied to the wiring L1. The in-vehicle charger 3 converts the AC power supplied from the AC charger via the connector CN2 into DC power and outputs it to the wiring L1. It can be said that the DC power is supplied to the wiring L1 from the AC charger via the connector CN2 and the in-vehicle charger 3. The wiring L2 is a wiring for supplying DC power to the load group 50. The DC power is supplied to the wiring L2 from one or both of the DC / DC converter 5 and the DC / DC converter 6. The voltage value of the DC power supplied to the wiring L2 is different from the voltage value of the DC power supplied to the wiring L1. The voltage value of the DC power supplied to the wiring L2 is, for example, 12V.

[0017] The battery 2 is a rechargeable secondary battery. Examples of the battery 2 include a lithium-ion battery, a lead-acid battery, and a nickel-metal hydride battery. The battery 2 may be a battery module including a plurality of battery cells. The battery 2 is connected to the wiring L1 and is charged by the DC power supplied to the wiring L1 by the DC charger or the in-vehicle charger 3.

[0018] The in-vehicle charger 3 includes an AC / DC converter, and as described above, converts the AC power supplied from the AC charger via the connector CN2 into DC power and outputs it to the wiring L1.

[0019] Switch 4 is a circuit element that can switch the electrical connection state at both ends thereof between a conductive state (on state) and a non-conductive state (off state). Switch 4 may be composed of, for example, a semiconductor such as a metal oxide semiconductor field effect transistor (MOSFET: Metal Oxide Semiconductor Field Effect Transistor) and an insulated gate bipolar transistor (IGBT: Insulated Gate Bipolar Transistor), or may be composed of a relay. Switch 4 is provided between the in-vehicle charger 3 and the wiring L1. When switch 4 is set to the conductive state, the in-vehicle charger 3 is electrically connected to the wiring L1. When switch 4 is set to the non-conductive state, the in-vehicle charger 3 is electrically disconnected from the wiring L1.

[0020] Each of the DC / DC converters 5 and 6 is a circuit that converts the voltage value of the DC power supplied to the wiring L1 into different voltage values and supplies DC power to the load group 50 via the wiring L2. The DC / DC converter 5 includes an input terminal 5a and an output terminal 5b. The input terminal 5a is connected to the wiring L1 via the filter section 7. The output terminal 5b is connected to the wiring L2. The DC / DC converter 6 includes an input terminal 6a and an output terminal 6b. The input terminal 6a is connected to the wiring L1 via the filter section 8. The output terminal 6b is connected to the wiring L2.

[0021] The DC / DC converters 5 and 6 are driven by the control unit 10. The switching frequency of the DC / DC converters 5 and 6 is, for example, about 170 kHz. When the vehicle V is in the charging mode, only the DC / DC converter 5 is used. The charging mode is an operation mode for charging the battery 2. When the vehicle V is in the running mode, either the DC / DC converter 5 or the DC / DC converter 6 may be used, or both may be used. The running mode is an operation mode in which the vehicle V runs.

[0022] The filter section 7 is the part for electrically connecting the wiring L1 and the DC / DC converter 5, and is connected to the wiring L1 and the DC / DC converter 5. The filter section 7 includes a filter circuit 71 (first filter circuit) and a switch 72 (first switch).

[0023] The filter circuit 71 is a low-pass filter and has a cutoff frequency fc1 (first cutoff frequency). Since the DC / DC converter 5 is used when the vehicle V is in charging mode, the cutoff frequency fc1 is set to a frequency that can remove low-frequency noise. The filter circuit 71 includes terminals 71a and 71b. Terminal 71a is connected to wiring L1 via switch 72, and terminal 71b is connected to input terminal 5a of the DC / DC converter 5. The gain characteristics of the filter circuit 71 will be described later.

[0024] The switch 72 is a circuit element that can switch the electrical connection state of its two ends between a conductive state (on state) and a non-conductive state (off state). The switch 72 may be made of semiconductors such as MOSFETs and IGBTs, or it may be made of a relay. One end of the switch 72 is connected between the switch 4 and the battery 2 in the wiring L1, and the other end of the switch 72 is connected to terminal 71a of the filter circuit 71. The filter unit 7 electrically connects the wiring L1 and the DC / DC converter 5 via the filter circuit 71 when the switch 72 is set to the conductive state. The filter unit 7 electrically disconnects the DC / DC converter 5 from the wiring L1 when the switch 72 is set to the non-conductive state.

[0025] The filter section 8 is the part for electrically connecting the wiring L1 and the DC / DC converter 6, and is connected to the wiring L1 and the DC / DC converter 6. The filter section 8 includes a filter circuit 81 (second filter circuit) and a switch 82 (second switch).

[0026] The filter circuit 81 is a low-pass filter and has a cutoff frequency fc2 (second cutoff frequency). The cutoff frequency fc2 is higher than the cutoff frequency fc1. Since the DC / DC converter 6 is used when the vehicle V is in driving mode, the cutoff frequency fc2 is set to a frequency that can remove noise above the FM band, for example. The filter circuit 81 includes terminals 81a and 81b. Terminal 81a is connected to wiring L1 via switch 82, and terminal 81b is connected to input terminal 6a of the DC / DC converter 6. The gain characteristics of the filter circuit 81 will be described later.

[0027] Switch 82 is a circuit element capable of switching the electrical connection state of its two ends between a conductive state (on state) and a non-conductive state (off state). Switch 82 may be made of semiconductors such as MOSFETs and IGBTs, or it may be made of a relay. One end of switch 82 is connected between switch 4 and battery 2 in wiring L1, and the other end of switch 82 is connected to terminal 81a of filter circuit 81. When switch 82 is set to the conductive state, filter unit 8 electrically connects wiring L1 and DC / DC converter 6 via filter circuit 81. When switch 82 is set to the non-conductive state, filter unit 8 electrically disconnects DC / DC converter 6 from wiring L1.

[0028] The control unit 10 is a device (controller) that provides overall control of the power supply system 1. The control unit 10 is composed of a CPU (Central Processing Unit), RAM (Random Access Memory), ROM (Read Only Memory), and input / output interfaces, etc. For example, the control unit 10 controls the onboard charger 3, switch 4, DC / DC converter 5, DC / DC converter 6, switch 72, and switch 82. The control unit 10 switches the connection state of switches 4, 72, and 82 according to the operating mode of the vehicle V. The switching control performed by the control unit 10 will be described later.

[0029] Next, the gain characteristics of filter circuits 71 and 81 will be explained with reference to Figures 2(a), 2(b), 3(a), and 3(b). Figure 2(a) shows the gain characteristics of filter circuit 71 when a signal passes through filter circuit 71 from DC / DC converter 5 toward wiring L1. Figure 2(b) shows the gain characteristics of filter circuit 71 when a signal passes through filter circuit 71 from wiring L1 toward DC / DC converter 5. Figure 3(a) shows the gain characteristics of filter circuit 81 when a signal passes through filter circuit 81 from DC / DC converter 6 toward wiring L1. Figure 3(b) shows the gain characteristics of filter circuit 81 when a signal passes through filter circuit 81 from wiring L1 toward DC / DC converter 6. In each figure, the horizontal axis represents frequency (unit: Hz) and the vertical axis represents gain (unit: dB).

[0030] As shown in Figures 2(a) and 2(b), the filter circuit 71 has different gain characteristics depending on the direction in which the signal passes through the filter circuit 71. When the signal passes through the filter circuit 71 from the DC / DC converter 5 toward the wiring L1 (when the signal passes through the filter circuit 71 from terminal 71b toward terminal 71a), the gain characteristic G11 of the filter circuit 71 shows a resonant frequency fr11 around 7MHz. When the signal passes through the filter circuit 71 from the wiring L1 toward the DC / DC converter 5 (when the signal passes through the filter circuit 71 from terminal 71a toward terminal 71b), the gain characteristic G12 of the filter circuit 71 shows a resonant frequency fr12 around 2.5MHz.

[0031] As shown in Figures 3(a) and 3(b), the filter circuit 81 has different gain characteristics depending on the direction in which the signal passes through the filter circuit 81. When the signal passes through the filter circuit 81 from the DC / DC converter 6 toward the wiring L1 (when the signal passes through the filter circuit 81 from terminal 81b toward terminal 81a), the gain characteristic G21 of the filter circuit 81 shows resonant frequencies fr21 around 900kHz and 13MHz. When the signal passes through the filter circuit 81 from the wiring L1 toward the DC / DC converter 6 (when the signal passes through the filter circuit 81 from terminal 81a toward terminal 81b), the gain characteristic G22 of the filter circuit 81 shows resonant frequencies fr22 around 2.2MHz and 13MHz.

[0032] As described later, the cutoff frequencies fc1 and fc2 are set so that the resonant frequencies fr11 and fr22 do not coincide, and the resonant frequencies fr12 and fr21 do not coincide.

[0033] Next, the operation of the power supply system 1 will be explained with reference to Figures 4 to 7. Figure 4 is a flowchart showing an example of switching control performed by the control unit shown in Figure 1. Figures 5 to 7 are diagrams illustrating an example of the operation of the power supply system. The process shown in Figure 4 is repeated, for example, at predetermined time intervals.

[0034] As shown in Figure 4, the control unit 10 first determines whether the vehicle V is in charging mode (step S1). In step S1, the control unit 10 determines that the vehicle V is in charging mode if it detects that a DC charger is connected to connector CN1, or if it detects that an AC charger is connected to connector CN2. When the control unit 10 detects that an AC charger is connected to connector CN2, it sets switch 4 to a conductive state and operates the on-board charger 3. As a result, if an AC charger is connected to connector CN2, the AC power supplied from the AC charger is converted to DC power and supplied to wiring L1, charging the battery 2. If a DC charger is connected to connector CN1, DC power is supplied from the DC charger to wiring L1, charging the battery 2.

[0035] If it is determined in step S1 that the vehicle V is in charging mode (step S1: YES), the control unit 10 determines whether or not it is necessary to supply DC power to the load group 50 (step S2). For example, if the control unit 10 detects that any of the loads 51 are operating, it determines that it is necessary to supply DC power to the load group 50. Here, even if the DC / DC converters 5 and 6 are not operating, each load 51 is supplied with the DC power necessary to start up the load 51 from an auxiliary battery (not shown).

[0036] If it is determined in step S2 that DC power needs to be supplied to the load group 50 (step S2: YES), the control unit 10 sets switch 72 to a conductive state, sets switch 82 to a non-conductive state, and operates the DC / DC converter 5, as shown in Figure 5 (step S3). At this time, the DC / DC converter 6 is not operating. As a result, the DC power supplied to wiring L1 is converted to a different voltage value by the DC / DC converter 5 and supplied to wiring L2. With this, the series of processes shown in Figure 4 is completed.

[0037] On the other hand, if it is determined in step S2 that it is not necessary to supply DC power to the load group 50 (step S2: NO), the control unit 10 sets switches 72 and 82 to a non-conductive state (step S4). At this time, DC / DC converters 5 and 6 are not operating. With this, the series of processes shown in Figure 4 is completed.

[0038] If it is determined in step S1 that the vehicle V is not in charging mode (step S1: NO), the control unit 10 determines whether or not it is necessary to supply DC power to the load group 50, similar to step S2 (step S5). If it is determined in step S5 that it is necessary to supply DC power to the load group 50 (step S5: YES), the control unit 10 determines whether or not the DC power supplied to the load group 50 is insufficient (step S6). For example, the control unit 10 compares the total power consumption of the operating loads 51 with the maximum power that can be supplied by the DC / DC converter 6, and determines that the DC power supplied to the load group 50 is insufficient if the total power consumption exceeds the maximum power that can be supplied.

[0039] If it is determined in step S6 that there is no shortage of DC power supplied to the load group 50 (step S6: NO), then, as shown in Figure 6, the control unit 10 sets switches 4 and 72 to a non-conductive state, sets switch 82 to a conductive state, and operates the DC / DC converter 6 (step S7). At this time, the DC / DC converter 5 is not operating. As a result, the DC power supplied from the battery 2 to wiring L1 is converted to a different voltage value by the DC / DC converter 6 and supplied to wiring L2. With this, the series of processes shown in Figure 4 is completed.

[0040] If it is determined in step S6 that the DC power supplied to the load group 50 is insufficient (step S6: YES), the control unit 10 sets switch 4 to a non-conductive state and switches 72 and 82 to a conductive state (step S8), as shown in Figure 7. Then, the control unit 10 operates DC / DC converter 5 in addition to DC / DC converter 6. As a result, the DC power supplied from battery 2 to wiring L1 is converted to different voltage values ​​by DC / DC converter 5 and DC / DC converter 6 and supplied to wiring L2. With this, the series of processes shown in Figure 4 is completed.

[0041] If it is determined in step S5 that it is not necessary to supply DC power to the load group 50 (step S5: NO), the control unit 10 sets switches 4, 72, and 82 to a non-conductive state (step S9). At this time, DC / DC converters 5 and 6 are not operating. With this, the series of processes shown in Figure 4 is completed.

[0042] In the power supply system 1 described above, when switch 72 is set to conduct, wiring L1 and DC / DC converter 5 are electrically connected via filter circuit 71, and when switch 82 is set to conduct, wiring L1 and DC / DC converter 6 are electrically connected via filter circuit 81. When DC power output from the onboard charger 3 or DC charger is supplied to wiring L1 (i.e., when the vehicle V is in charging mode), and it is determined that DC power needs to be supplied to the load group 50, switches 4 and 72 are set to conduct, switch 82 is set to non-conductive, and the DC / DC converter 5 is controlled. As a result, wiring L1 and DC / DC converter 5 are electrically connected via filter circuit 71, which can reduce noise in the lower frequency band than filter circuit 81, thus suppressing the transmission of low-frequency noise to the AC charger or DC charger.

[0043] On the other hand, when vehicle V is in motion (vehicle V is in driving mode), DC / DC converters 5 and 6 are not electrically connected to an external power supply. Therefore, there is no need to suppress low-frequency noise that can be suppressed by filter circuit 71 but not by filter circuit 81, and DC / DC converter 6 can be driven. As a result, when the load group 50 requires a lot of DC power, driving DC / DC converters 5 and 6 makes it possible to supply a lot of DC power to the load group 50. Furthermore, although filter circuit 81 can only suppress noise in a higher frequency band than filter circuit 71, it is smaller in scale and less expensive than filter circuit 71. Therefore, a power supply system 1 that can supply a lot of power to the load group and suppress the transmission of low-frequency noise to an external power supply can be provided at a low cost, and the size of the power supply system 1 can be kept down.

[0044] As shown in Figure 7, when switches 72 and 82 are set to conduct, DC / DC converters 5 and 6 operate simultaneously. As a result, noise generated by the other DC / DC converter is input to one DC / DC converter, and this noise can cause the voltage value at the output terminal to fluctuate. Specifically, noise generated by the switching operation of DC / DC converter 5 may be transmitted through path P1, which passes sequentially through filter circuit 71, switch 72, wiring L1, switch 82, filter circuit 81, and DC / DC converter 6. In this case, if the resonant frequency fr11 of filter circuit 71 (the resonant frequency of filter circuit 71 when a signal passes through filter circuit 71 from DC / DC converter 5 toward wiring L1) and the resonant frequency fr22 of filter circuit 81 (the resonant frequency of filter circuit 81 when a signal passes through filter circuit 81 from wiring L1 toward DC / DC converter 6) coincide, the noise may not be sufficiently reduced by resonance, and the fluctuation range of the voltage value at output terminal 6b of DC / DC converter 6 may exceed the allowable range of the input voltage of load group 50.

[0045] Similarly, noise generated by the switching operation of the DC / DC converter 6 may be transmitted through path P2, which passes sequentially through filter circuit 81, switch 82, wiring L1, switch 72, filter circuit 71, and DC / DC converter 5. In this case, if the resonant frequency fr12 of filter circuit 71 (the resonant frequency of filter circuit 71 when a signal passes through filter circuit 71 from wiring L1 toward DC / DC converter 5) and the resonant frequency fr21 of filter circuit 81 (the resonant frequency of filter circuit 81 when a signal passes through filter circuit 81 from DC / DC converter 6 toward wiring L1) coincide, the noise may not be sufficiently reduced by resonance, and the fluctuation range of the voltage value at the output terminal 5b of the DC / DC converter 5 may exceed the allowable range of the input voltage of the load group 50.

[0046] In contrast, in power supply system 1, the cutoff frequencies fc1 and fc2 are set such that the resonant frequency fr11 of filter circuit 71 and the resonant frequency fr22 of filter circuit 81 do not match, and the resonant frequency fr12 of filter circuit 71 and the resonant frequency fr21 of filter circuit 81 do not match. With this configuration, since the resonant frequencies of filter circuit 71 and filter circuit 81 do not match in each path, it is possible to suppress the voltage fluctuation range at the output terminal 5b of DC / DC converter 5 and the voltage fluctuation range at the output terminal 6b of DC / DC converter 6 from exceeding the allowable range of the input voltage of the load group 50. Therefore, power can be supplied stably to the load group 50.

[0047] In power supply system 1, when it is necessary to supply DC power to the load group 50 in driving mode, the DC / DC converter 6 is used first. This control reduces the frequency with which the DC / DC converter 5 is used compared to a configuration in which the DC / DC converter 5 is used first in driving mode, thereby reducing the possibility of failure of the DC / DC converter 5.

[0048] Although one embodiment of the present disclosure has been described in detail above, the power supply system relating to the present disclosure is not limited to the above embodiment.

[0049] In the above embodiment, in step S7, the control unit 10 sets switch 72 to a non-conductive state, sets switch 82 to a conductive state, and drives the DC / DC converter 6. Alternatively, the control unit 10 may set switch 72 to a conductive state, set switch 82 to a non-conductive state, and drive the DC / DC converter 5. In other words, in the driving mode, the DC / DC converter 5 is used first, and the DC / DC converter 6 may be used if the DC / DC converter 5 alone cannot supply sufficient power.

[0050] If it is determined that DC power needs to be supplied to the load group 50 in driving mode (step S5: YES), the control unit 10 may set switches 72 and 82 to a conductive state and drive DC / DC converters 5 and 6, regardless of whether there is insufficient power or not.

[0051] Filter circuits 71 and 81 are not limited to fixed filters, but may also be variable filters.

[0052] Even if the resonant frequency fr11 of filter circuit 71 and the resonant frequency fr22 of filter circuit 81 coincide, depending on the noise level at that frequency, the fluctuation range of the voltage value at the output terminal 6b of DC / DC converter 6 may fall within the allowable range of the input voltage of load group 50. Similarly, even if the resonant frequency fr12 of filter circuit 71 and the resonant frequency fr21 of filter circuit 81 coincide, depending on the noise level at that frequency, the fluctuation range of the voltage value at the output terminal 5b of DC / DC converter 5 may fall within the allowable range of the input voltage of load group 50.

[0053] Therefore, the cutoff frequencies fc1 and fc2 should be set such that the voltage fluctuation range at the output terminal 5b of the DC / DC converter 5 and the voltage fluctuation range at the output terminal 6b of the DC / DC converter 6, when switches 72 and 82 are set to conduct, falls within the allowable range of the input voltage of the load group 50. With this configuration, the voltage fluctuation range at the output terminal 5b of the DC / DC converter 5 and the voltage fluctuation range at the output terminal 6b of the DC / DC converter 6 fall within the allowable range of the input voltage of the load group 50, thus enabling the supply of stable DC power to the load group 50.

[0054] The filter unit 7 does not necessarily have to include switch 72, and the filter unit 8 does not necessarily have to include switch 82. Furthermore, the power supply system 1 does not necessarily have to include switch 4. In other words, at least one of switch 4, switch 72, and switch 82 does not need to be provided.

[0055] The location where switch 4 is provided is not limited to between the onboard charger 3 and the wiring L1. For example, switch 4 may be provided closer to the battery 2 than the connection point on the wiring L1 to which the onboard charger 3 is connected, and closer to the connection point to which the onboard charger 3 is connected than either the connection point on the wiring L1 to which the filter unit 7 is connected or the connection point on the wiring L1 to which the filter unit 8 is connected. In this configuration as well, the filter unit 7 does not have to include switch 72, and the filter unit 8 does not have to include switch 82.

[0056] Switch 4 may be provided between the connection point on wiring L1 to which filter unit 7 is connected and the connection point on wiring L1 to which filter unit 8 is connected, and the connection point on wiring L1 to which battery 2 is connected. In this configuration as well, filter unit 7 does not have to include switch 72, and filter unit 8 does not have to include switch 82. [Explanation of symbols]

[0057] 1...Power supply system, 2...Battery (DC power supply), 3...Onboard charger, 5...DC / DC converter (1st DC / DC converter), 5b...Output terminal, 6...DC / DC converter (2nd DC / DC converter), 6b...Output terminal, 7...Filter section (1st filter section), 8...Filter section (2nd filter section), 10...Control unit, 50...Load group, 51...Load, 71...Filter circuit, 72...Switch, 81...Filter circuit, 82...Switch, L1...Wiring, L2...Wiring, V...Vehicle.

Claims

1. A power supply system installed in a vehicle, Wiring that receives DC power from an external power source, A DC power supply connected to the aforementioned wiring, A first DC / DC converter that converts the DC power supplied to the wiring into different voltage values ​​and outputs them to a group of loads including at least one load, A first filter section having a first cutoff frequency and connected to the wiring and the first DC / DC converter, A second DC / DC converter that converts the DC power supplied to the wiring into a different voltage value and outputs it to the load group, A second filter section having a second cutoff frequency higher than the first cutoff frequency and connected to the wiring and the second DC / DC converter, A control unit that controls the first DC / DC converter and the second DC / DC converter, Equipped with, When DC power is supplied from the external power supply to the wiring and it is necessary to supply DC power to the load group, the control unit controls the first DC / DC converter. A power supply system in which the first cutoff frequency and the second cutoff frequency are set such that the voltage fluctuation range at the output terminal of the first DC / DC converter and the voltage fluctuation range at the output terminal of the second DC / DC converter fall within the allowable range of the input voltage of the load group.

2. The power supply system according to claim 1, wherein the first cutoff frequency and the second cutoff frequency are set such that the resonant frequency of the first filter when a signal passes through the first filter when a signal passes through the first filter when a signal passes through the second filter when a signal passes through the second filter when a signal passes through the second filter when a signal passes through the second DC / DC converter from the first DC / DC converter does not coincide, and the resonant frequency of the first filter when a signal passes through the first filter when a signal passes through the second filter when a signal passes through the second filter when a signal passes through the second filter when a signal passes through the second filter when a signal passes through the second filter when a signal passes through the second filter when a signal passes through the second filter when a signal passes through the second DC / DC converter from the first DC / DC converter.

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