Energy distribution system

Abstract

Energy distribution system (110) comprising: a first terminal (116) to be connected to a first battery (101); a second terminal (117) to be connected to a second battery (102); a load terminal (118) to be connected to a load (131, 132); a bidirectional DC-DC converter (114) connected between the first terminal (116) and the second terminal (117); a first relay (111) connected between the first terminal (116) and the load terminal (118); a second relay (112) connected between the second terminal (117) and the load terminal (118);and a control unit (120) for controlling an operating direction of the bidirectional DC-DC converter (114), an opening and closing actuation of the first relay (111) and an opening and closing actuation of the second relay (112), characterized in that the connections between the bidirectional DC-DC converter (114) and the first terminal (116) and the second terminal (117) are each direct and uninterrupted and the control unit (120), when it detects a fault only of the first battery (101), stops the bidirectional DC-DC converter (114), opens the first relay (111) and closes the second relay (112).

Description

Background of the invention Field of invention The present invention relates to a distribution system that connects a main battery and an auxiliary battery to distribute energy to a consumer. Description of the related technique In recent years, technological advancements have been made in the development of ADAS (Advanced Driving Safety Assistance Systems) and automatic transmission systems. Since the control unit and its various sensors operate using electrical energy, their function cannot be adequately maintained if the power supply from the grid is delayed. To prevent such situations, multiple batteries have been installed in the vehicle to ensure a redundant power supply. With regard to the redundancy of the power supply, patent document 1 discloses a power supply device as shown in Fig. 8. In this power supply device, the main battery 301 and the auxiliary battery 302 provide redundant power supply, and both batteries are connected to the power supply box 331. A load 322, such as a motor, and a load 323, such as a light fixture, are connected in parallel in the power supply box 331. A microcomputer 332 is provided in the power supply box 331, and a power supply monitoring unit 333 and a relay control unit 334 are provided. The power supply monitoring unit 333 monitors the output voltages of the main battery 301 and the auxiliary battery 302 and controls the relay control unit 334 based on the monitoring result, thereby controlling the opening and closing of the relay 312 of the main battery system and the relay 313 of the auxiliary battery system. According to the power supply device described in the Japanese unexamined patent application with publication number JP 2015-214274 A, it is possible, for example, to implement controls for comparing the output voltages of the main battery 301 and the auxiliary battery 302 and to supply the load with power from the battery that has the higher output voltage, or to prevent the load from being supplied with power from the battery whose output voltage is lower than the specified threshold. As a result, it becomes possible to supply the load with a constant power supply even if one of the batteries fails. German patent application DE 10 2012 200 804 A1 describes an electrical system for a vehicle with three branches. A first branch includes a first energy storage device and a first electrical consumer. A second branch includes a second energy storage device and (optionally) a second electrical consumer. A third branch includes a third electrical consumer. The electrical system also comprises a DC / DC converter and a generator. German patent application DE 102 51 589 A1 describes an electrical system for a vehicle with two sub-systems. Each sub-system has its own battery. A consumer is connected to both sub-systems in such a way that redundancy of the power supply is guaranteed in the event of a failure. If both sub-systems are capable of supplying power, the system controls the supply so that the power is provided by the more powerful sub-system. A DC-DC converter is provided between the two sub-systems. Overview of the invention When a redundant power supply is used, a lithium-ion battery has been adopted as a backup battery instead of a conventional lead-acid battery. Although a lithium-ion battery offers the advantages of high energy density, small size, and light weight, strict voltage monitoring is required during charging, and therefore a bidirectional DC-DC converter is generally used. The bidirectional DC-DC converter connected to the lithium-ion battery can operate in three states: charging, discharging, and standby. These operating modes require appropriate control depending on the vehicle's condition and other factors. Therefore, in the power supply device shown in Fig. 8, if a bidirectional DC-DC converter and a lithium-ion battery are used instead of the auxiliary battery 302, a simple on / off control for relays, similar to the conventional one, cannot improve the reliability achievable with the redundant battery. Furthermore, to improve reliability, it is also desirable to consider not only the failure of the battery itself, but also the failure of the relay, etc. Therefore, in a case where a bidirectional DC-DC converter is connected to a power supply, and the power supply is designed to be redundant, the objective of the present invention is to improve the reliability of the supply of electrical energy to a consumer. This is achieved by the features of the independent claims. Further features of advantageous embodiments of the present invention are the subject of dependent claims. According to the present invention, if the power supply is designed redundantly, the reliability of the consumer's power supply can be improved in a case where a bidirectional DC-DC converter is connected to a power supply. Brief description of the drawings Fig. 1 is a diagram illustrating a vehicle power supply device according to a present embodiment; Fig. 2 is a functional block diagram of a control unit; Figs. 3A to 3C are diagrams explaining control contents of a relay control unit and a DC-DC converter control unit; Figs. 4A and 4B are diagrams explaining a power transfer path during normal driving; Figs. 5A and 5B are diagrams explaining a power transfer path when a battery fails; Figs. 6A to 6C are diagrams explaining a power transfer path in the event of a fault; Figs. 7A to 7D are diagrams explaining a power transfer path in the event of a double fault; and Fig. 8 is a diagram showing an example of conventional power supply redundancy. Detailed description of the preferred embodiment Embodiments of the present invention are described in detail with reference to the drawings. Fig. 1 is a diagram illustrating a power supply device 100 of a vehicle according to one embodiment. The power supply device 100 is designed such that a power source is redundantly configured with a main battery 101 and an auxiliary battery 102, and both batteries are connected to the power distribution system 110. Furthermore, the energy distribution system 110 is equipped with a first consumer 131, such as a brake ECU, and a second consumer 132, such as an ADAS ECU, which is connected to it. These consumers require a stable energy supply while the vehicle is in motion. However, the consumers connected to the energy distribution system 110 are not limited to these. The main battery 101 can, for example, be a lead-acid battery (Pb). Furthermore, the auxiliary battery 102 can, for example, be a lithium-ion battery (LiB). Since a lithium-ion battery (LiB) requires strict voltage monitoring during charging, the power distribution system 110 includes a bidirectional DC-DC converter 114. However, the battery used as the auxiliary battery 102 is not limited to a lithium-ion battery. For example, a capacitor or the like can be used. Furthermore, the energy distribution system 110 includes an internal control relay 111, a switching relay 112, a control unit 120, a main terminal 116 to be connected to the main battery 101, an auxiliary terminal 117 to be connected to the auxiliary battery 102, and a consumer terminal 118 to be connected to the consumer. In the example shown in this figure, several consumer terminals 118 are connected in parallel, with the first consumer 131 connected to consumer terminal 118a and the second consumer 132 connected to consumer terminal 118b. An AC generator 103 is also connected to the main terminal 116. A relay, power supply wiring, a fuse, a load, etc., which are unnecessary for the description of the present embodiment, are not described here. The power distribution system 110 is further distinguished between a bidirectional DC-DC converter 114 and a power distribution unit, which is formed by components other than the power distribution unit. The bidirectional DC-DC converter 114 and the power distribution unit are structured for integration. This makes it possible to reduce the diameter of the power supply wires connecting the two and to improve noise immunity by minimizing the signal transmission line. The bidirectional DC voltage converter 114 is connected between the main terminal 116 and the auxiliary terminal 117, the IG relay 111 is connected between the main terminal 116 and the consumer terminal 118, and the switching relay 112 is connected between the auxiliary terminal 117 and the consumer terminal 118. For example, the main battery 101 serves as the first battery, the main connection 116 as the first connection, and the IG relay 111 as the first relay. Furthermore, the auxiliary battery 102 serves as the second battery, the auxiliary connection 117 as the second connection, and the switching relay 112 as the second relay. The bidirectional DC-DC converter 114, which is connected to the auxiliary battery 102 via the auxiliary terminal 117, can switch between three operating states: charging, discharging, and standby. In charging mode, energy is transferred from the main terminal 116 to the auxiliary terminal 117, and in discharging mode, energy is transferred from the auxiliary terminal 117 to the main terminal 116. Whether or not the voltage is stepped up or down is irrelevant in this context. Standby mode is a state in which energy is not transferred in either direction. The control unit 120 can be designed using a microcomputer or the like and controls, according to a program or the like, the operating direction of the bidirectional DC voltage converter 114, the opening and closing actuation of the IG relay 111, the closing actuation of the switching relay 112 and the like. Fig. 2 is a functional block diagram of the control unit 120. As shown in the figure, the control unit 120 is equipped with a main battery fault detection unit 121, an auxiliary battery fault detection unit 122, a driving condition determination unit 123, a relay fault detector 124, a DC voltage converter fault detector 125, a relay control unit 126 and a DC voltage converter control unit 127. The main battery fault detection unit 121 detects a fault in the main battery 101. The fault in the main battery 101 is caused by a voltage drop in the main battery 101, an open circuit in a power supply line of the main battery system, a short circuit in the power supply line of the main battery system, etc. The main battery fault detection unit 121 monitors the output voltage of the main battery 101, etc., thereby detecting the fault in the main battery 101. The auxiliary battery fault detector 122 detects a fault in the auxiliary battery 102. The fault in the auxiliary battery 102 is caused by a voltage drop in the auxiliary battery 102, an open circuit in the auxiliary battery system's power supply line, a short circuit in the auxiliary battery system's power supply line, etc. The auxiliary battery fault detector 122 monitors, for example, the output voltage of the auxiliary battery 102, thereby detecting the fault in the auxiliary battery 102. The driving state detection unit 123 determines whether the vehicle is in a normal driving state or a coasting state while driving. Coasting is a state in which the engine is stopped after acceleration and the vehicle is driven at inertial speed. For example, the driving state detection unit 123 exchanges data with the host device, thereby differentiating the driving state. The relay fault detection unit 124 detects whether the IG relay 111 and the switching relay 112 are in a fault state (always open). For example, the relay fault detection unit 124 identifies a relay fault if the control state is not detected, regardless of any closing control. The DC-DC converter fault detection unit 125 detects the fault of the bidirectional DC-DC converter 114. For example, the DC-DC converter fault detection unit 125 detects a fault of the bidirectional DC-DC converter 114 by exchanging data with the bidirectional DC-DC converter 114. The relay control unit 126 controls the opening and closing operations of the internal relay 111 and the switching relay 112. The DC-DC converter control unit 127 controls the operating direction of the bidirectional DC-DC converter. Based on the detection results from the battery fault detection unit 121, the auxiliary battery fault detection unit 122, the driving condition determination unit 123, the relay fault detection unit 124, and the DC-DC converter fault detection unit 125, the relay control unit 126 and the DC-DC converter fault detection unit 127 perform control of each of these, as described below. Fig. 3 illustrates the control contents of the relay control unit 126 and the DC-DC converter control unit 127. In this figure, a state in which the vehicle drives normally (Fig. 3A), a state in which a fault or the like occurs in one of the main battery 101, the auxiliary battery 102, the bidirectional DC-DC converter 114, the IG relay 111 and the switching relay 112 (Fig. 3B), and a state in which a double fault occurs (Fig. 3C) are distinguished. In the present embodiment, it is assumed that there is an extremely low probability that the IG relay 111 and the switching relay 112 will fail simultaneously and that the main battery 101 and the auxiliary battery 102 will fail simultaneously, so these are not assumed. In a state of normal driving (Fig. 3A), that is, when none of the main battery fault detection unit 121, the auxiliary battery fault detection unit 122, the relay fault detection unit 124 and the DC-DC converter fault detection unit 125 has detected an irregularity and when normal driving is taking place, the relay control unit 126 switches the IG relay 111 on (closed) and switches the switching relay 112 off (open), and the DC-DC converter control unit 127 sets the operating direction of the bidirectional DC-DC converter 114 to the charging direction. As a result, the consumer is supplied with energy from the main battery 101 and the AC generator 103. In addition, the auxiliary battery 102 is charged. Fig. 4A schematically illustrates the energy supply path. In contrast, when sailing in a state where the vessel is under normal driving conditions, the relay control unit 126 switches on the IG relay 111 and switches off the switching relay 112, and the DC-DC converter control unit 127 sets the operating direction of the bidirectional DC-DC converter 114 to the discharge direction. This is because the AC generator 103 does not produce any electricity while sailing. As a result, the consumer is supplied with energy from the main battery 101 and the auxiliary battery 102. Fig. 4B schematically illustrates the energy supply path at this point. In a state where a fault occurs at one point (Fig. 3B), that is, when any of the main battery fault detection unit 121, the auxiliary battery fault detection unit 122, the relay fault detection unit 124, the DC voltage converter fault detection unit 125 detects a fault, the following control is carried out. In the event of a main battery fault, the relay control unit 126 switches off the IG relay 111 and switches on the switching relay 112, and the DC voltage converter control unit 127 stops the bidirectional DC voltage converter 114. As a result, the consumer is supplied with energy from the auxiliary battery 102. Fig. 5A schematically illustrates the energy supply path at this point. In the event of an auxiliary battery fault, the relay control unit 126 switches on the IG relay 111 and switches off the switching relay 112, and the DC voltage converter control unit 127 stops the bidirectional DC voltage converter 114. As a result, the consumer is supplied with energy from the main battery 101. Fig. 5B schematically illustrates the energy supply path at this point. In addition to the main battery 101, energy can also be supplied from the AC generator 103. In the event of a fault in the bidirectional DC-DC converter 114, the relay control unit 126 switches on the internal relay 111 and switches off the switching relay 112. As a result, the load is supplied with energy from the main battery 101 and the AC generator 103. Fig. 6A schematically illustrates the power supply path at this point. If the IG relay 111 fails, the relay control unit 126 switches on the switching relay 112, and the DC-DC converter control unit 127 sets the operation of the bidirectional DC-DC converter 114 to the charging direction. As a result, the load is supplied with energy from the main battery 101. In addition, the auxiliary battery 102 is charged. Fig. 6B schematically illustrates the energy supply path at this point. In addition to the main battery 101, energy can be supplied from the AC generator 103. In the event of a fault in the switching relay 112, the relay control unit 126 switches on the internal relay 111. Furthermore, the DC-DC converter control unit 127 sets the operation of the bidirectional DC-DC converter 114 to the charging direction. As a result, the load is supplied with energy from the main battery 101. Additionally, the auxiliary battery 102 is charged. Fig. 6C schematically illustrates the energy supply path at this point. In addition to the main battery 101, energy can also be supplied from the AC generator 103. In a condition where a double fault occurs (Fig. 3C), that is, when two of the main battery fault detection unit 121, the auxiliary battery fault detector 122, the relay fault detector 124, the DC voltage converter fail, the following control is carried out. If the main battery fault and the IG relay fault occur simultaneously, the relay control unit 126 switches on the switching relay 112, and the DC voltage converter control unit 127 stops the bidirectional DC voltage converter 114. As a result, the consumer is supplied with energy from the auxiliary battery 102. Fig. 7A schematically illustrates the energy supply path at this point. If the main battery fault and the switching relay fault occur simultaneously, the relay control unit 126 switches on the IG relay 111, and the DC voltage converter control unit 127 sets the operating direction of the bidirectional DC voltage converter 114 to the discharge direction. As a result, the consumer is supplied with energy from the auxiliary battery 102. Fig. 7B schematically illustrates the energy supply path at this point. If the auxiliary battery fault and the IG relay fault occur simultaneously, the relay control unit 126 switches on the switching relay 112, and the DC voltage converter control unit 127 sets the operating direction of the bidirectional DC voltage converter 114 to the charging direction. As a result, the consumer is supplied with energy from the main battery 101. Fig. 7C schematically illustrates the energy supply path at this point. In addition to the main battery 101, energy can also be supplied from the AC generator 103. If the auxiliary battery fault and the switching relay fault occur simultaneously, the relay control unit 126 switches on the IG relay 111, and the DC voltage converter control unit 127 stops the bidirectional DC voltage converter 114. As a result, the consumer is supplied with energy from the main battery 101. Fig. 7D schematically illustrates the energy supply path at this point. In addition to the main battery 101, energy can also be supplied from the AC generator 103. As described above, in the power supply system 110 of the present embodiment, the bidirectional DC-DC converter is connected between the main terminal 116 and the auxiliary terminal 117, and the switching relay 112 is connected between the auxiliary terminal 117 and the load terminal 118. Consequently, by interrupting the power supply path, taking into account the loss of the battery itself in addition to the malfunction of the relay and the bidirectional DC-DC converter, it is possible to improve the reliability of the load's power supply. Description of the reference symbols: 100 Power supply 101 Main battery 102 Auxiliary battery 103 Alternator 110 Power distribution system 111 Internal relay 112 Switching relay 114 Bidirectional DC-DC converter 116 Main connection 117 Auxiliary connection 118 Consumer connection 120 Control unit 121 Main battery fault detector 122 Auxiliary battery fault detector 123 Driving condition differentiation unit 124 Relay fault detection unit 125 DC-DC converter fault detection unit 126 Relay control unit 127 DC-DC converter control unit 131 First consumer 132 Second consumer

Claims

Energy distribution system (110) comprising: a first terminal (116) to be connected to a first battery (101); a second terminal (117) to be connected to a second battery (102); a load terminal (118) to be connected to a load (131, 132); a bidirectional DC-DC converter (114) connected between the first terminal (116) and the second terminal (117); a first relay (111) connected between the first terminal (116) and the load terminal (118); a second relay (112) connected between the second terminal (117) and the load terminal (118);and a control unit (120) for controlling an operating direction of the bidirectional DC-DC converter (114), an opening and closing actuation of the first relay (111) and an opening and closing actuation of the second relay (112), characterized in that the connections between the bidirectional DC-DC converter (114) and the first terminal (116) and the second terminal (117) are each direct and uninterrupted and the control unit (120), when it detects a fault only of the first battery (101), stops the bidirectional DC-DC converter (114), opens the first relay (111) and closes the second relay (112). Energy distribution system (110) according to claim 1, wherein the control unit (120) detects a state in which energy is supplied from the first battery (101) and a state in which energy is supplied from the second battery (102) in order to perform the controls. Energy distribution system (110) according to claim 2, wherein the control unit (120) further detects an operating state of the bidirectional DC voltage converter (114) in order to perform the controls. Energy distribution system (110) according to claim 2 or 3, wherein the control unit (120) further detects an operating state of the first relay (111) and the second relay (112) in order to perform the controls. Energy distribution system (110) comprising: a first terminal (116) to be connected to a first battery (101); a second terminal (117) to be connected to a second battery (102); a load terminal (118) to be connected to a load (131, 132); a bidirectional DC-DC converter (114) connected between the first terminal (116) and the second terminal (117); a first relay (111) connected between the first terminal (116) and the load terminal (118); a second relay (112) connected between the second terminal (117) and the load terminal (118);and a control unit (120) for controlling the operating direction of the bidirectional DC-DC converter (114), the opening and closing of the first relay (111), and the opening and closing of the second relay (112), characterized in that when the control unit (120) detects faults in the first battery and the second relay (112), it causes the bidirectional DC-DC converter (114) to conduct energy from the second battery (102) to the first terminal (116), closes the first relay (111), and opens the second relay (112).

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