Vehicle power supply system

Abstract

This vehicle power supply system provides a mechanism that can appropriately limit the operation of auxiliary loads regardless of whether a malfunction occurs in the alternator or the DC-DC converter. [Solution] A power supply system mounted on a vehicle, comprising a DC-DC converter that supplies battery power to an auxiliary load, an alternator connected in parallel with the DC-DC converter so as to be able to supply power generated by the engine drive to the auxiliary load, and a control device that controls the auxiliary load based on the state of the DC-DC converter and the alternator, wherein the control device restricts the operation of the auxiliary load if the power consumption of the auxiliary load exceeds the maximum value of the rated output power of the DC-DC converter, if the engine speed is below a first threshold, or if the engine speed is above the first threshold but the alternator is not operating, or if the alternator is operating but the operating rate is above a second threshold.

Description

Technical Field

[0006] , , , ,

[0001] The present disclosure relates to a vehicle power supply system mounted on a vehicle.

Background Art

[0002] Patent Document 1 discloses a vehicle power supply system that supplies power to auxiliary loads using an alternator and a DCDC converter as power sources. This power supply system describes restricting the operation of auxiliary loads when an abnormality occurs in the alternator.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the power supply system described in Patent Document 1 above, since the case where an abnormality occurs in the DCDC converter is not assumed, there is a problem that the operation of the auxiliary load cannot be appropriately restricted when an abnormality occurs in the DCDC converter.

[0005] The present disclosure has been made in view of the above problems, and an object thereof is to provide a vehicle power supply system capable of appropriately restricting the operation of an auxiliary load even when an abnormality occurs in either the alternator or the DCDC converter.

Means for Solving the Problems

[0006] To solve the above problems, one aspect of the disclosed technology is a vehicle power supply system comprising: a DC-DC converter that supplies battery power to an auxiliary load; an alternator connected in parallel with the DC-DC converter so as to be able to supply power generated by the engine drive to the auxiliary load; and a control device that controls the auxiliary load based on the state of the DC-DC converter and the alternator, wherein the control device restricts the operation of the auxiliary load if the power consumption of the auxiliary load exceeds the maximum value of the rated output power of the DC-DC converter, if the engine speed is below a first threshold, or if the engine speed is above the first threshold but the alternator is not operating, or if the alternator is operating but the operating rate is above a second threshold. [Effects of the Invention]

[0007] According to the vehicle power supply system described above, since the state of both the alternator and the DC-DC converter is determined, the operation of auxiliary loads can be appropriately limited regardless of whether a malfunction occurs in the alternator or the DC-DC converter. [Brief explanation of the drawing]

[0008] [Figure 1] Block diagram of a vehicle power supply system and its surrounding area according to one embodiment of the present disclosure. [Figure 2] Flowchart of the process for auxiliary equipment load operation control performed by the vehicle power system [Modes for carrying out the invention]

[0009] The vehicle power supply system of this disclosure monitors the engine speed (driving state), the operating rate of the alternator, and the output state of the DCDC converter, and appropriately applies necessary operating limits to the auxiliary load based on these. The embodiments of this disclosure will be described in detail below with reference to the drawings.

[0010] <Embodiment> [composition] Figure 1 is a functional block diagram showing the schematic configuration of a vehicle power supply system 100 and its surrounding parts according to one embodiment of the present disclosure. The functional block illustrated in Figure 1 includes an engine 110, an alternator 120, a drive battery 130, a DC-DC converter 140, an auxiliary battery 150, an auxiliary load 160, an engine control device 170, and an HEV control device 180. In Figure 1, wiring for power transmission is shown with solid lines, and wiring for information and instructions is shown with dotted lines.

[0011] This vehicle power supply system 100 can be installed in vehicles such as hybrid electric vehicles (HEVs) and plug-in hybrid electric vehicles (PHEVs) that use an internal combustion engine 110 and an electric motor (not shown) as power sources.

[0012] Engine 110 is an internal combustion engine that generates the rotation necessary for the alternator 120 to generate electricity. The power of engine 110 may be used to drive the vehicle, or it may be used to charge the drive battery 130 or the auxiliary battery 150 via the alternator 120. The operation of engine 110 is controlled by engine control device 170. In addition, information on the engine speed [rpm] indicating the operating status of engine 110 is output (transmitted) from engine 110 to engine control device 170. The above information can be detected by a predetermined sensor provided in engine 110.

[0013] The alternator 120 is a generator that can produce electricity in accordance with the rotation of the engine 110. This alternator 120 is connected in parallel with the DC-DC converter 140 so that it can supply its own generated power, along with the power from the DC-DC converter 140, to the auxiliary battery 150 and auxiliary loads 160. Whether or not the alternator 120 can output generated power is controlled by the engine control device 170. In addition, information on the operating rate [%], which indicates the current power generation status relative to the alternator 120's maximum power generation capacity, is output (transmitted) from the alternator 120 to the engine control device 170. The above information can be detected by a predetermined sensor provided on the alternator 120.

[0014] The drive battery 130 is a rechargeable secondary battery, such as a lithium-ion battery. The drive battery 130 can output the power it has stored to the DC-DC converter 140. The drive battery 130 can also charge the power generated by the alternator 120 or the power stored in the auxiliary battery 150 via the DC-DC converter 140.

[0015] The DC-DC converter 140 is installed between the drive battery 130 and the auxiliary load 160. It is a generator that converts the power from the drive battery 130, which is the power supply source, into power of a voltage suitable for the auxiliary load 160 and outputs it to the auxiliary load 160. The operation of this DC-DC converter 140 is controlled by the HEV control device 180. Information [V,A] regarding the output status of the DC-DC converter (DDC) 140 is also output (transmitted) to the HEV control device 180. This information can be detected by a predetermined sensor provided in the DC-DC converter 140.

[0016] The auxiliary battery 150 is a rechargeable secondary battery, such as a lithium-ion battery or a lead-acid battery. The auxiliary battery 150 can output the power it stores to the auxiliary load 160. This auxiliary battery 150 uses a battery with a lower rated voltage than the drive battery 130.

[0017] The auxiliary load 160 is one or more power-consuming auxiliary electronic devices or equipment mounted on the vehicle. This auxiliary load 160 is configured, in principle, to operate using power from the drive battery 130 supplied via the DCDC converter 140 and power generated by the alternator 120, and is configured to operate using power from the auxiliary battery 150 in certain situations. Furthermore, the operation of the auxiliary load 160 is appropriately limited according to instructions from the HEV control device 180 based on the states of the engine 110, alternator 120, and DCDC converter 140.

[0018] The engine control device 170 acquires information regarding the driving state (engine speed, alternator operating rate) from the engine 110 and alternator 120, respectively, and controls the operation of the engine 110 and alternator 120 based on this information. The information acquired from the engine 110 and alternator 120 is output (transmitted) to the HEV control device 180.

[0019] The HEV control device 180 acquires information regarding the drive state (DDC output state) from the DCDC converter 140 and information regarding engine speed and alternator operating rate from the engine control device 170, and controls the operation of the DCDC converter 140 based on this information. In addition, the HEV control device 180 restricts the operation of the auxiliary load 160 based on the above information. Examples of restrictions on operation include disabling some functions of the auxiliary load 160 or setting upper and lower limits on its operating range.

[0020] Part or all of the above-described engine control device 170 and HEV control device 180 can typically be configured by one or more electronic control units (ECUs) including a processor such as a microcomputer, a memory, and an input / output interface. By the processor reading and executing the program stored in the memory, part or all of the functions performed by the above-described engine control device 170 and HEV control device 180 can be realized.

[0021] [Control] Next, referring further to FIG. 2, the control performed by the vehicle power supply system 100 according to an embodiment of the present disclosure will be described. FIG. 2 is a flowchart for explaining the processing procedure of auxiliary load operation control executed by the engine control device 170 and the HEV control device 180 of the vehicle power supply system 100.

[0022] The auxiliary load operation control illustrated in FIG. 2 is started when the vehicle power supply system 100 is activated (Ready-ON) and is repeatedly executed until the vehicle power supply system 100 is stopped (Ready-OFF).

[0023] (Step S201) The HEV control device 180 determines whether the DCDC converter 140 has reached its power generation limit. More specifically, the HEV control device 180 determines whether the power consumed by the auxiliary load 160 exceeds the maximum value of the rated output power of the predetermined DCDC converter 140. That is, when the power consumption of the auxiliary load 160 exceeds the maximum rated output power of the DCDC converter 140, it is determined that the DCDC converter 140 has reached its power generation limit. This determination can be made based on the DDC output state (voltage, current) obtained from the DCDC converter 140.

[0024] If it is determined that the DC-DC converter 140 has reached its power generation limit (step S201, yes), the process proceeds to step S202. On the other hand, if it is determined that the DC-DC converter 140 has not reached its power generation limit (step S201, no), the process proceeds to step S203.

[0025] (Step S202) The engine control device 170 instructs the alternator 120 to drive in order to satisfy the power demand of the auxiliary load 160, because the DCDC converter 140 has reached its power generation limit. If the alternator 120 is already driving, it instructs it to continue driving. Once the alternator 120 is instructed to drive, the process proceeds to step S204.

[0026] (Step S203) The engine control device 170 instructs the alternator 120 to stop driving because the DCDC converter 140 has not reached its power generation limit and the power demand of the auxiliary load 160 can be met by the DCDC converter 140 alone. If the alternator 120 has already stopped driving, it instructs it to continue stopping. Once the alternator 120 is instructed to stop, the process proceeds to step S209.

[0027] (Step S204) The HEV control device 180 determines whether the state in which the DCDC converter 140 has reached its power generation limit continues for a predetermined time. This determination takes into account the delay time (time lag) from when the engine control device 170 gives a drive command to the alternator 120 in step S202 until the alternator 120 actually starts moving. Therefore, the predetermined time is set to any value that is greater than or equal to this time lag.

[0028] If it is determined that the DC-DC converter 140 has been in a state of power generation limit for a predetermined time (step S204, yes), the process proceeds to step S205. On the other hand, if it is determined that the DC-DC converter 140 has not been in a state of power generation limit for a predetermined time (step S204, no), the process proceeds to step S209.

[0029] (Step S205) The engine control device 170 determines whether the rotational speed of the engine 110 is below a first threshold. This determination is made to confirm whether the engine 110 is running after waiting for a time lag. The first threshold is set to a predetermined value that confirms the engine 110 is running, based on the structure and performance of the engine 110.

[0030] If it is determined that the rotational speed of engine 110 is below the first threshold (step S205, yes), it is determined that the alternator 120 is not being driven based on the drive instruction, and the process proceeds to step S208. On the other hand, if it is determined that the rotational speed of engine 110 is equal to or greater than the first threshold (step S205, no), it is determined that the alternator 120 is being driven based on the drive instruction, and the process proceeds to step S206.

[0031] (Step S206) The engine control device 170 determines whether the alternator 120 is operating in response to the engine 110 being driven. This determination is made to confirm whether the engine 110 is rotating normally at a rotational speed at which the alternator 120 can generate power. Whether the alternator 120 is operating can be determined by whether the operating rate of the alternator 120 is zero or not.

[0032] If it is determined that the alternator 120 is operating (step S206, yes), it is determined that there is no abnormality in the alternator 120, and the process proceeds to step S207. On the other hand, if it is determined that the alternator 120 is not operating (step S206, no), it is determined that there is an abnormality in the alternator 120, or that the engine 110 is not being driven at a rotational speed above the speed at which the alternator 120 can generate electricity, and the process proceeds to step S208.

[0033] (Step S207) The engine control device 170 determines whether the operating rate of the alternator 120 is above a second threshold. This determination is made to check whether the alternator 120 is operating close to its power generation limit. Therefore, this second threshold is arbitrarily set based on the operating rate at which the alternator 120 reaches its power generation limit.

[0034] If it is determined that the operating rate of alternator 120 is above the second threshold (step S207, yes), it is determined that alternator 120 is operating close to its power generation limit, and the process proceeds to step S208. On the other hand, if it is determined that the operating rate of alternator 120 is below the second threshold (step S207, no), it is determined that there is still some margin before alternator 120 reaches its power generation limit, and the process proceeds to step S209.

[0035] (Step S208) The HEV control device 180 issues an instruction to limit the operation of the auxiliary load 160. This limitation instruction reduces the power consumed by the auxiliary load 160. The power consumption of the auxiliary load 160 after the reduction may be less than or equal to the power generation limit of the DCDC converter 140 alone, or less than or equal to the power generation limit of the DCDC converter 140 and the alternator 120 combined. In the former case, only the DCDC converter 140 operates, and in the latter case, both the DCDC converter 140 and the alternator 120 operate. When an instruction to limit the operation of the auxiliary load 160 is issued (operation restriction), the process returns to step S201.

[0036] (Step S209) The HEV control device 180 does not issue an instruction to restrict the operation of the auxiliary load 160. Therefore, in this case, power is consumed according to the demand of the auxiliary load 160. If there is no restriction on the operation of the auxiliary load 160, the process returns to step S201.

[0037] <Effects and Actions> As described above, according to the vehicle power supply system 100 according to one embodiment of the present disclosure, in a power supply configuration in which a DCDC converter 140 and an alternator 120 are connected in parallel as a power supply source for an auxiliary load 160, if the power consumption of the auxiliary load 160 exceeds the maximum value of the rated output power of the DCDC converter 140, the operation of the auxiliary load 160 is restricted if the rotational speed of the engine 110 is less than a first threshold, or if the rotational speed of the engine 110 is above the first threshold but the alternator 120 is not operating, or if the alternator 120 is operating but its operating rate is above a second threshold.

[0038] This limitation on the operation of the auxiliary load 160 ensures that the limitation on the operation of the auxiliary load 160 is properly implemented regardless of whether a malfunction occurs in the alternator 120 or the DC-DC converter 140.

[0039] Although one embodiment of the present disclosure has been described above, the present disclosure can be understood not only as a vehicle power supply system, but also as a method executed by a vehicle power supply system equipped with a processor, memory, etc., a program for executing this method, a computer-readable non-temporary storage medium storing the program, and a vehicle equipped with the vehicle power supply system. [Industrial applicability]

[0040] The vehicle power supply system of this disclosure can be used in vehicles equipped with a power supply system comprising a DC-DC converter and an alternator, etc. [Explanation of symbols]

[0041] 100 Vehicle Power System 110 engine 120 Alternator 130 Power Battery 140 DC-DC converters 150 Auxiliary Battery 160 Auxiliary load 170 Engine control unit 180 HEV control unit

Claims

1. A power supply system installed in a vehicle, A DC-DC converter that supplies battery power to auxiliary loads, An alternator connected in parallel with the DC-DC converter so that it can supply the power generated by the engine's operation to the auxiliary load, The system includes a control device that controls the auxiliary load based on the state of the DC-DC converter and the alternator, The control device restricts the operation of the auxiliary load if the power consumption of the auxiliary load exceeds the maximum value of the rated output power of the DC-DC converter, if the engine speed is below a first threshold, or if the engine speed is above the first threshold but the alternator is not operating, or if the alternator is operating but the operating rate is above a second threshold. Vehicle power system.

2. The first threshold is the rotational speed at which the alternator can generate electricity. The vehicle power supply system according to claim 1.

3. The second threshold is the operating rate that indicates the power generation limit of the alternator. The vehicle power supply system according to claim 1.

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