Vehicle power supply system

Abstract

The vehicle power system includes a main DC-DC converter and an auxiliary battery, a secondary DC-DC converter, a first switch and a second switch connected in series between the main power system and the secondary power system, and a control unit. The main DC-DC converter and the auxiliary battery are connected to a first load connected to the main power system in a manner capable of supplying power. The secondary DC-DC converter is connected to a second load connected to the secondary power system in a manner capable of supplying power. In the event of a failure of the main DC-DC converter, the control unit controls the first and second switches to stop the load that does not need to operate during the failure, and supplies power to the first load after the voltage of the secondary DC-DC converter returns to normal.

Description

Technical Field

[0001] This disclosure relates to a power system installed in a vehicle. Background Technology

[0002] Japanese Patent Application Publication No. 2023-032346 discloses a vehicle power system with the following structure: a main power system connected to a main power source and an auxiliary battery, and an auxiliary power system connected to a secondary power source, which are electrically connected via a switch. In this vehicle power system, if an abnormality occurs in one of the power systems, the switch is turned off to disconnect that power system, and the vehicle continues to operate using the normal power system of the other.

[0003] There are situations where, in the event of a main power supply failure in the main power system, power is supplied from the auxiliary power system to the loads of the main power system as a backup. In this case, if loads that do not need to operate during backup power supply to the auxiliary power system remain operational, the power supply capacity of the auxiliary power system may be insufficient.

[0004] Additionally, there are cases where a DC-DC converter is used to control the output of the auxiliary power supply. In this case, if the auxiliary power supply is connected to the main power system before the DC-DC converter's voltage control is complete, there is a possibility of overcharging the auxiliary battery of the main power system. Summary of the Invention

[0005] This disclosure was made in view of the above-mentioned problems, and its object is to provide a vehicle power system that can reduce the possibility of insufficient power supply capacity of the auxiliary power source and prevent overcharging of the auxiliary battery.

[0006] To address the aforementioned issues, one aspect of the present disclosure is a vehicle power system that supplies power to a load mounted on a vehicle. This vehicle power system includes: a main DC-DC converter connected to a first load in a manner capable of supplying power; an auxiliary battery connected to the first load in a manner capable of supplying power; a secondary DC-DC converter connected to a second load in a manner capable of supplying power; a first switch and a second switch connected in series between the main power system and the secondary power system; and a control unit that controls the first switch, the second switch, and the secondary DC-DC converter. In the event of a failure of the main DC-DC converter, the control unit controls the first switch and the second switch to stop the load that does not require operation during the failure, and supplies power to the first load after the voltage of the secondary DC-DC converter returns to normal.

[0007] According to the vehicle power system disclosed above, the possibility of insufficient power supply capacity of the auxiliary power source can be reduced, and overcharging of the auxiliary battery can be prevented. Attached Figure Description

[0008] The features, advantages, and technical and industrial significance of exemplary embodiments of the present invention will be described below with reference to the accompanying drawings, wherein like reference numerals denote like parts, wherein:

[0009] Figure 1 This is a schematic diagram of the structure of a vehicle power system and its peripheral components, which includes an embodiment of the present disclosure.

[0010] Figure 2 This is a diagram showing a variation of the auxiliary power source;

[0011] Figure 3A This is a flowchart of the auxiliary power connection control process executed by the vehicle power system.

[0012] Figure 3B This is a flowchart of the auxiliary power supply connection control process executed by the vehicle's power system; and

[0013] Figure 4 This diagram illustrates an application example of connecting a vehicle's power system to the loads of a partitioned structure. Detailed Implementation

[0014] In the event of a main power system failure, the vehicle power system disclosed herein reduces the load on the auxiliary system to a level that can be handled by the auxiliary battery and the secondary DC-DC converter. Furthermore, it verifies that the voltage of the secondary DC-DC converter is normal and connects a relay that connects the secondary DC-DC converter to the auxiliary battery.

[0015] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings.

[0016] Implementation

[0017] constitute

[0018] Figure 1 This is a schematic diagram illustrating an example of the structure of a vehicle power system 100 and its peripheral components, which includes an embodiment of the present disclosure. Figure 1 The illustrated vehicle power system 100 includes a main DC-DC converter (main DDC) 110 as the main power system, an auxiliary battery 120, a main power distribution control unit 130, and an auxiliary power supply 200 as the auxiliary power system. This vehicle power system 100 is, for example, mounted in a vehicle.

[0019] The main DC-DC converter 110 is a power converter. This power converter converts the voltage (e.g., 48V) of the power input from a high-voltage battery such as a lithium-ion battery (not shown) to the required voltage (e.g., 12V) and outputs it to the main power distribution control unit 130.

[0020] The auxiliary battery 120 is a rechargeable battery, such as a lithium-ion battery. This auxiliary battery 120 can supply the power it stores to the main power distribution control unit 130.

[0021] The main power distribution control unit 130 is a structure (such as a power distribution ECU) used to supply and control power to multiple loads 140-160 (first loads) of various devices and equipment mounted on the vehicle. This power supply source (main power supply source) is the main DC-DC converter 110 and the auxiliary battery 120. The main power distribution control unit 130 supplies power via multiple switches 131-137 based on the control unit 138. The multiple switches 131-137 are semiconductor relays. Furthermore, this... Figure 1 The number and configuration of the multiple switches 131-137 shown are for illustrative purposes only and are not limited thereto.

[0022] The auxiliary power supply 200 functions as a power source for multiple loads 230-250. Furthermore, the auxiliary power supply 200 functions as a backup power source in the event of a failure of the main power system. This auxiliary power supply 200 includes a secondary DC-DC converter (secondary DDC) 210 and a secondary power distribution control unit 220.

[0023] The secondary DC-DC converter 210 is a power converter. This power converter converts the voltage (e.g., 48V) of the power input from the same high-voltage battery (not shown) as the primary DC-DC converter 110 to the required voltage (e.g., 12V) and outputs it to the secondary power distribution control unit 220.

[0024] The secondary power distribution control unit 220 is a structure (such as a power distribution ECU) used to supply and control power to multiple loads 230-250 (secondary loads) by using the secondary DC-DC converter 210 as a power supply source (secondary power supply source). This secondary power distribution control unit 220 supplies power via multiple switches 221-224 based on the control of the control unit 225. The multiple switches 221-224 are semiconductor relays. Furthermore, this... Figure 1 The number and configuration of the multiple switches 221-224 shown are for illustrative purposes only and are not limited thereto.

[0025] Variations

[0026] Figure 2 This is a variation of the vehicle power system 100 that uses an auxiliary power supply 300 with a different structure than the auxiliary power supply 200. The auxiliary power supply 300 involved in this variation can be applied to situations where multiple loads 230-250 (secondary loads) include loads that operate at different voltages.

[0027] The auxiliary power supply 300 includes a first auxiliary DC-DC converter (first auxiliary DDC) 311 and an auxiliary power distribution control unit 320. The auxiliary power distribution control unit 320 includes a second auxiliary DC-DC converter (second auxiliary DDC) 312, multiple switches 221-224, and a control unit 225.

[0028] The first DC-DC converter 311 adjusts the voltage of the power input from the high-voltage battery to the voltage required by loads 230 and 240 (e.g., 48V) and outputs it to the secondary power distribution control unit 320. The second DC-DC converter 312 converts the voltage of the power input from the first DC-DC converter 311 (e.g., 48V) to the voltage required by load 250 (e.g., 12V).

[0029] By employing a secondary power supply 300 with a structure having multiple first secondary DC-DC converters 311 and second secondary DC-DC converters 312, it is possible to supply power with optimal voltage to multiple loads 230-250 respectively.

[0030] control

[0031] Next, further reference Figure 3A and Figure 3B This describes an example of control implemented in a vehicle power system 100 according to one embodiment of the present disclosure. Figure 3A and Figure 3B This is a flowchart illustrating the processing steps of the auxiliary power supply connection control performed by the control unit 138 of the main power distribution control unit 130 and the control unit 225 of the auxiliary power distribution control unit 220 (or 320). Figure 3A processing and Figure 3B The processing is done through the connection symbol X.

[0032] Should Figure 3A as well as Figure 3B The illustrated auxiliary power supply connection control begins when the power supply from the main DC-DC converter 110 to the main power distribution control unit 130 stops due to an abnormality in the main DC-DC converter 110, etc. When the power supply stops, the control unit 138 controls the switch 133 to the off state.

[0033] S301

[0034] Control unit 138 controls switch 137 (hereinafter referred to as "first switch 137") of main power distribution control unit 130 to the off state (OFF). Additionally, control unit 225 controls switch 221 (hereinafter referred to as "second switch 221") of auxiliary power distribution control unit 220 to the off state (OFF). This control unit 225 performs control based on instructions from control unit 138 that detects a power supply stoppage to main DC-DC converter 110 (the same applies in the following steps).

[0035] If both the first switch 137 and the second switch 221 are controlled to the cut-off state (open), the process proceeds to S302.

[0036] S302

[0037] Control units 138 and 225 switch the vehicle to a degraded driving state. For example, degraded driving refers to driving used to safely pull a vehicle that has malfunctioned to a curb or similar location. During the transition to degraded driving, control unit 138 restricts only the operating loads from loads 140-160 (auxiliary system loads) connected to the main power distribution control unit 130 to the loads required for degraded driving. Control unit 225 restricts only the operating loads from loads 230-250 (secondary system loads) connected to the auxiliary power distribution control unit 220 to the loads required for degraded driving. The restriction method can be to cut off the power supply to the load by disconnecting a switch, or to issue a stop instruction to the load.

[0038] When the vehicle's state changes to degraded driving and the workload is limited, the process enters S303.

[0039] S303

[0040] The control unit 225 sets the output voltage (sub-DC voltage Vs) of the auxiliary DC-DC converter 210 to voltage V1. This voltage V1 can be set, for example, to a voltage (e.g., Vb-1 volt) based on the output voltage (battery voltage Vb) of the auxiliary battery 120, taking into account the Vf voltage of the transistor used for the semiconductor relay.

[0041] If the output voltage (sub-DC voltage Vs) of the secondary DC-DC converter 210 is set to voltage V1, then the process proceeds to S304.

[0042] S304

[0043] The control unit 225 determines whether the output voltage (sub-DDC voltage Vs) of the sub-DC converter 210 is controlled to the set voltage V1. This determination can be made, for example, by setting the tolerance of the control deviation to α (0.5 volts, etc.) according to the conditions of Equation 1 below.

[0044] V1-α<Vs<V1+α …[Equation 1]

[0045] If the output voltage (sub-DC voltage Vs) of the sub-DC converter 210 satisfies the condition of Equation 1 above (S304, Yes), the process proceeds to S306. On the other hand, if the output voltage (sub-DC voltage Vs) of the sub-DC converter 210 does not satisfy the condition of Equation 1 above (S304, No), the process proceeds to S305.

[0046] S305

[0047] Control units 138 and 225 control the vehicle by notifying its display device or other devices that it cannot continue driving when an abnormality occurs in the output voltage control of the auxiliary DC-DC converter 210 (DDC voltage control abnormality). Additionally, this notification may be accompanied by prompting the vehicle to stop immediately or secure itself.

[0048] When notification that operation cannot continue due to an abnormality in the output voltage control of the auxiliary DC-DC converter 210 (DDC voltage control abnormality), the auxiliary power supply connection control ends.

[0049] S306

[0050] The control unit 225 controls the second switch 221 of the auxiliary power distribution control unit 220 to the ON state. In addition, the first switch 137 of the main power distribution control unit 130 remains in the OFF state.

[0051] If the second switch 221 is controlled to be in the ON state, the process proceeds to S307.

[0052] S307

[0053] Control unit 138 obtains the voltage applied to main power distribution control unit 130 from auxiliary power distribution control unit 220. More specifically, control unit 138 obtains the voltage (input voltage Vm) appearing at the terminal of first switch 137 in the wiring connecting first switch 137 and second switch 221. Additionally, control unit 225 obtains the current supplied from auxiliary power distribution control unit 220 to main power distribution control unit 130. More specifically, control unit 225 obtains the current flowing out from the terminal of second switch 221 in the aforementioned wiring (output current Is).

[0054] If the voltage (input voltage Vm) appearing at the first switch 137 terminal and the current flowing out from the second switch 221 terminal (output current Is) are obtained, the process proceeds to S308.

[0055] S308

[0056] The control unit 138 determines whether the voltage (input voltage Vm) appearing at the first switch 137 exceeds a predetermined threshold voltage Vth. This determination is made to determine whether the wiring connecting the first switch 137 and the second switch 221 is broken. Therefore, the threshold voltage Vth is set based on the voltage appearing at the first switch 137 assuming the aforementioned wiring is broken (e.g., 3 volts).

[0057] If the voltage (input voltage Vm) appearing at the first switch 137 exceeds the threshold voltage Vth (S308, Yes), the process proceeds to S310. On the other hand, if the voltage (input voltage Vm) appearing at the first switch 137 does not exceed the threshold voltage Vth (S308, No), the process proceeds to S309.

[0058] S309

[0059] Control units 138 and 225 control the vehicle to notify its display device or similar device that it cannot continue driving when an abnormality (disconnection) occurs in the wiring connecting the first switch 137 and the second switch 221. Additionally, this notification may be accompanied by prompting the vehicle to stop immediately or secure itself.

[0060] When a notification is received that the vehicle cannot continue to operate due to a broken wire (broken wire fault) in the wiring connecting the first switch 137 and the second switch 221, the auxiliary power supply connection control is terminated.

[0061] S310

[0062] The control unit 225 determines whether the current flowing out of the second switch 221 (output current Is) is below a predetermined threshold current Ith. This determination is made to determine whether the wiring connecting the first switch 137 and the second switch 221 is grounded. Therefore, the threshold current Ith is set based on the current flowing out of the second switch 221 assuming that the wiring is grounded (e.g., 5 amps).

[0063] If the current flowing out of the second switch 221 (output current Is) is below the threshold current Ith (S310, Yes), the process proceeds to S312. On the other hand, if the current flowing out of the second switch 221 (output current Is) exceeds the threshold current Ith (S310, No), the process proceeds to S311.

[0064] S311

[0065] Control units 138 and 225 control the vehicle to notify its display device or similar device that it cannot continue driving when there is a grounding abnormality (circuit grounding abnormality) in the wiring connecting the first switch 137 and the second switch 221. Additionally, this notification may be accompanied by prompting the vehicle to stop immediately or secure itself.

[0066] When a grounding anomaly (circuit grounding anomaly) occurs in the wiring connecting the first switch 137 and the second switch 221, indicating that the vehicle cannot continue to operate, the auxiliary power supply connection control ends.

[0067] S312

[0068] The control unit 225 controls the second switch 221 of the auxiliary power distribution control unit 220 to the OFF state. In addition, the first switch 137 of the main power distribution control unit 130 remains in the OFF state.

[0069] When the second switch 221 is controlled to be in the off state (OFF), the process enters S313.

[0070] S313

[0071] The control unit 225 sets the output voltage (sub-DC voltage Vs) of the auxiliary DC-DC converter 210 to a predetermined voltage V2. The predetermined voltage V2 is between the output voltage (battery voltage Vb) of the auxiliary battery 120 and an upper limit voltage (battery upper limit voltage Vmax) to prevent overcharging of the auxiliary battery 120. This voltage V2 can be set, for example, according to the conditions in Equation 2 below. Additionally, α is the control deviation tolerance.

[0072] Vb + α < V2 < Vmax … [Equation 2]

[0073] If the output voltage (sub-DC voltage Vs) of the sub-DC converter 210 is set to voltage V2, the process proceeds to S314. Furthermore, since there is a response delay between the voltage and the setting, it is preferable to proceed to the process in S314 after confirming that the sub-DC voltage Vs has risen to voltage V2.

[0074] S314

[0075] Control unit 138 controls the first switch 137 of the main power distribution control unit 130 to the ON state. In addition, control unit 225 controls the second switch 221 of the auxiliary power distribution control unit 220 to the ON state.

[0076] Furthermore, the control that puts the first switch 137 and the second switch 221 into the conducting state is implemented while the vehicle is in motion. This is to prevent the voltage of the main power distribution control unit 130 from dropping due to inrush current flowing from the auxiliary power distribution control unit 220 to the main power distribution control unit 130, thereby causing the loads 140-160 to reset.

[0077] If both the first switch 137 and the second switch 221 are controlled to the ON state, the process proceeds to S315.

[0078] S315

[0079] The control unit 138 acquires the current supplied from the secondary power distribution control unit 220 to the main power distribution control unit 130. More specifically, the control unit 138 acquires the current (input current Im) flowing into the first switch 137 terminal from the wiring connecting the first switch 137 and the second switch 221.

[0080] When the current (input current Im) flowing into the first switch 137 is obtained, the process enters S316.

[0081] S316

[0082] The control unit 138 determines whether the current flowing into the first switch 137 (input current Im) is not zero, i.e., not "0". This determination is made to determine whether the main power distribution control unit 130 is being supplied with power normally from the auxiliary power supply 200.

[0083] If the current flowing into the first switch 137 (input current Im) is not zero (S316, yes), the process proceeds to S318. On the other hand, if the current flowing into the first switch 137 (input current Im) is zero (S316, no), the process proceeds to S317.

[0084] S317

[0085] Control units 138 and 225 control the vehicle to notify its display devices that it cannot continue driving. Additionally, this notification may be accompanied by prompts to urge the vehicle to stop immediately or secure itself.

[0086] When notified that the vehicle cannot continue to operate, terminate the control of this auxiliary power supply connection.

[0087] S318

[0088] Control units 138 and 225 perform control to notify the system of an anomaly. Furthermore, upon receiving this notification, the vehicle can be urged to stop while continued driving is permitted.

[0089] When a power system malfunction is detected, the connection control of this auxiliary power supply is terminated.

[0090] Functions and effects

[0091] As described above, a vehicle power system 100 according to one embodiment of this disclosure includes a main DC-DC converter 110, an auxiliary battery 120, and a secondary DC-DC converter 210. The main DC-DC converter 110 and the auxiliary battery 120 are connected to a plurality of loads 140-160 (first loads) connected to a main power distribution control unit 130 in a manner capable of supplying power. The secondary DC-DC converter 210 is connected to a plurality of loads 230-250 (second loads) connected to a secondary power distribution control unit 220 in a manner capable of supplying power. In the event of a failure of the main DC-DC converter 110, loads that do not require operation during the failure are stopped. Furthermore, control is performed to supply power to the plurality of loads 140-160 (first loads) via switches 137 and 221 after the voltage of the secondary DC-DC converter 210 returns to normal.

[0092] This control reduces the likelihood of insufficient power supply to the auxiliary power source 200 for degraded operation in the event of a failure (stop) of the main DC-DC converter 110 due to a malfunction or other reasons. Simultaneously, it prevents overcharging of the auxiliary battery 120 by the power supplied from the auxiliary power source 200.

[0093] Application examples

[0094] When the auxiliary power supply 200 (or 300) is added to the vehicle power system 100, a portion of the load 140-160 connected to the main power distribution control unit 130 can also be connected to the auxiliary power distribution control unit 220 (or 320). Alternatively, a portion of the second load 230-250 connected to the auxiliary power supply 200 (or 300)'s auxiliary power distribution control unit 220 (or 320) can also be connected to the main power distribution control unit 130. Such load replacement can be arbitrarily implemented depending on the load's mounting location and installation site within the vehicle.

[0095] Furthermore, the vehicle power system 100 of this embodiment can also be connected to... Figure 4 The load connection of the area structure is shown. Figure 4 In the illustrated area structure, the load 140 connected to the main power distribution control unit 130 (area 1) is replaced by multiple loads 141 and 142 connected to the power distribution control unit 410 (area 2). Furthermore, the load 150 connected to the main power distribution control unit 130 (area 1) is replaced by multiple loads 151, 152, and 153 connected to the power distribution control unit 420 (area 3). The vehicle power system 100 of this embodiment can also be applied to loads with such an area structure.

[0096] The vehicle power system disclosed herein can be applied to vehicles that can operate in a degraded manner by utilizing the power of the auxiliary power system in the event of a failure of the main power system.

Claims

1. A vehicle power supply system for supplying power to a load mounted on a vehicle, wherein, The vehicle power system includes: The main DC-DC converter is connected to the first load of the main power system in a manner that enables it to supply power. An auxiliary battery is connected to the first load in a manner that enables it to supply power. A secondary DC-DC converter is connected to a second load connected to the secondary power supply system in a manner that enables it to supply power. The first switch and the second switch are connected in series between the main power system and the auxiliary power system; as well as The control unit controls the first switch, the second switch, and the secondary DC-DC converter. In the event of a failure of the main DC-DC converter, the control unit controls the first switch and the second switch to stop the load that does not need to operate during the failure, and supplies power to the first load after the voltage of the secondary DC-DC converter returns to normal.

2. The vehicle power system according to claim 1, wherein, The control unit controls the second switch when the first switch on the main power system side is turned off to determine whether there are any voltage control abnormalities, open circuit abnormalities, or grounding abnormalities in the auxiliary DC-DC converter. If it is determined that none of the aforementioned abnormalities exist, the control unit turns on the first switch and the second switch.

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