Auxiliary power supply unit, control method of auxiliary power supply unit, and steering control device

Abstract

The auxiliary power supply unit (1) of the present application is provided with an auxiliary power supply device (71) and a downstream power supply line set (72) connecting the auxiliary power supply device to a motor unit (13, 32). The auxiliary power supply device (71) is provided with an auxiliary power supply (111) provided in a power supply path for assisting power supply from an external power supply (45) to the motor unit, and a switching circuit (114) configured to switch the connection state of the auxiliary power supply with respect to the power supply path. The connection state of the auxiliary power supply includes a step-up state in which the auxiliary power supply is connected in series with the external power supply between the external power supply and the motor unit. The downstream power supply line set (72) includes a branched first downstream drive line (161, 162) and a branched second downstream drive line (163, 164). Furthermore, the respective upstream end portions of the branched first downstream drive line and the branched second downstream drive line are connected to the power supply path closer to the downstream side than the auxiliary power supply.

Description

Technical Field

[0001] This disclosure relates to an auxiliary power supply unit, a control method for the auxiliary power supply unit, and a steering control device. Background Technology

[0002] Conventionally, for example, Patent Document 1, from a safety perspective, has described vehicle steering systems with redundant drive systems. This vehicle steering system includes: two steering motors that generate steering force, two control units that control the corresponding steering motors, and two power supplies. Normally, each control unit drives its corresponding steering motor based on power from one of the two power supplies. However, if one of the power supplies malfunctions, each control unit drives its corresponding steering motor based on power from the other power supply. Thus, even if one power supply malfunctions, the steering wheels can continue to be steered using both steering motors.

[0003] Patent Document 1: Japanese Patent Application Publication No. 2004-276833

[0004] However, in situations such as static maneuvers (steering while the vehicle is stationary) or emergency steering maneuvers to avoid obstacles while the vehicle is moving, a large amount of power needs to be temporarily supplied to the steering motor from the power source to generate a larger steering force. To meet such power demands, a power source with a larger capacity must be used, resulting in a larger power supply.

[0005] Furthermore, this problem is not limited to supplying power to motors used as drive sources for steering mechanisms; it can also occur with any power source, such as motors used for other purposes, when the power demand temporarily increases. Summary of the Invention

[0006] One aspect of this disclosure discloses an auxiliary power supply unit that supplies power from an external power source to a power supply object having multiple power supply systems. The auxiliary power supply unit includes: an auxiliary power supply device disposed midway in a power supply path from the external power source to the power supply object; and a power supply line assembly, forming part of the power supply path, connecting the auxiliary power supply device to the power supply object. The auxiliary power supply device includes: an auxiliary power source disposed in the power supply path to assist in the power supply from the external power source to the power supply object; and a switching circuit configured to switch the connection state of the auxiliary power source relative to the power supply path. The connection state of the auxiliary power source includes a boost state in which the auxiliary power source and the power supply object are connected in series. The power supply line assembly includes multiple discrete power supply lines connected to the multiple power supply systems. The upstream end of each of the multiple discrete power supply lines is connected to the power supply path closer to the downstream end than the auxiliary power source.

[0007] One aspect of the auxiliary power supply unit control method disclosed herein is a method for supplying power from an external power source to a power supply object having multiple power supply systems. The auxiliary power supply unit includes: an auxiliary power supply device disposed midway in a power supply path from the external power source to the power supply object; and a power supply line group, forming part of the power supply path, connecting the auxiliary power supply device to the power supply object. The auxiliary power supply device includes: an auxiliary power source disposed in the power supply path to assist in the power supply from the external power source to the power supply object; and a switching circuit configured to switch the connection state of the auxiliary power source relative to the power supply path. The connection state of the auxiliary power source includes a boost state in which the auxiliary power source is connected in series with the external power source between the external power source and the power supply object. The power supply line group includes multiple discrete power supply lines connected to the multiple power supply systems. Each of the multiple discrete power supply lines is connected to the power supply path closer to a downstream side than the auxiliary power source. The control method includes: determining whether the external power supply is normal; determining whether the condition for supplying a large amount of power to the power source is met; and controlling the switching circuit so that the connection state of the auxiliary power supply becomes the boost state when the voltage of the external power supply is normal and the condition is met.

[0008] One aspect of the steering control device of this disclosure includes: a motor unit having multiple power supply systems; and an auxiliary power supply unit of any aspect of this disclosure, which supplies power from an external power source to the motor unit. Attached Figure Description

[0009] Figure 1 This is a schematic diagram showing the structure of a steering control device having an auxiliary power supply unit according to the first embodiment.

[0010] Figure 2 It means Figure 1 A block diagram of the electrical structure of the steering control device.

[0011] Figure 3 It means Figure 2 A block diagram of the electrical structure of the auxiliary power supply unit.

[0012] Figure 4 It means by Figure 2 The flowchart shows the processing steps performed by the auxiliary power control unit of the auxiliary power supply unit to determine the connection status of the auxiliary power supply.

[0013] Figure 5 It means to make Figure 2 A diagram illustrating the power supply when the auxiliary power supply in the auxiliary power supply unit is in a charging state.

[0014] Figure 6 It means to make Figure 2 A diagram illustrating the power supply when the auxiliary power supply in the auxiliary power supply unit is in standby mode.

[0015] Figure 7 It means to make Figure 2 The diagram illustrates the power supply when the auxiliary power supply in the auxiliary power supply unit is connected in a boost state.

[0016] Figure 8 This is a block diagram showing the electrical structure of the auxiliary power supply unit in the second embodiment.

[0017] Figure 9 It means to make Figure 8 A diagram illustrating the power supply when the connection states of the first auxiliary power supply and the second auxiliary power supply in the auxiliary power supply unit are in a charging state.

[0018] Figure 10 It means to make Figure 8 The diagram illustrates the power supply when the connection state of the first auxiliary power supply in the auxiliary power supply unit is in standby mode and the connection state of the second auxiliary power supply is in charging mode.

[0019] Figure 11 It means to make Figure 8 The diagram illustrates the power supply when the connection state of the first auxiliary power supply in the auxiliary power supply unit is in the charging state and the connection state of the second auxiliary power supply is in the standby state.

[0020] Figure 12 It means to make Figure 8A diagram illustrating the power supply when the connection states of the first auxiliary power supply and the second auxiliary power supply in the auxiliary power supply unit are in a boost state. Detailed Implementation

[0021] (First Implementation)

[0022] Hereinafter, a first embodiment of the auxiliary power supply unit, the control method of the auxiliary power supply unit, and the steering control device will be described with reference to the accompanying drawings. In this embodiment, the auxiliary power supply unit 1 supplies power to the steering control device 2 mounted on the vehicle.

[0023] (Overall structure)

[0024] like Figure 1 As shown, the steering control device 2 is a steer-by-wire type steering control device. The steering control device 2 includes a reaction force unit 4 operated by the driver via the steering wheel 3, and a steering unit 6 that turns the steering wheels 5 according to the driver's operation of the reaction force unit 4. The steering control device 2 has a structure in which the power transmission paths between the reaction force unit 4 and the steering unit 6 are always mechanically separated.

[0025] The reaction force unit 4 includes a steering shaft 11 connected to the steering wheel 3 and a reaction force actuator 12 that applies an operating reaction force to the steering wheel 3 to resist steering operations.

[0026] The reaction force actuator 12 includes a reaction force motor unit 13 and a reaction force-side reducer 14. The reaction force motor unit 13 includes a reaction force motor 15 and a reaction force control device 16 for controlling the reaction force motor 15. The reaction force motor 15 is connected to the steering shaft 11 via the reaction force-side reducer 14. Thus, the motor torque of the reaction force motor 15 is supplied to the steering wheel 3 via the steering shaft 11.

[0027] The steering unit 6 includes a first pinion shaft 21 and a rack shaft 22 connected to the first pinion shaft 21. The first pinion shaft 21 is configured to intersect the rack shaft 22 at a predetermined angle. The first pinion shaft 21 has first pinion teeth 21a, and the rack shaft 22 has first rack teeth 22a. The first pinion shaft 21 and the rack shaft 22 are connected by the meshing of the first pinion teeth 21a and the first rack teeth 22a. That is, the first pinion shaft 21 and the rack shaft 22 constitute a first rack and pinion mechanism. Thus, the first pinion shaft 21 rotates by the reciprocating motion of the rack shaft 22. At both ends of the rack shaft 22, tie rods 24 are connected via ball joints 23. The front end of each tie rod 24 is connected to a steering knuckle (not shown) on which the steering wheel 5 is assembled.

[0028] Additionally, the steering unit 6 includes a steering actuator 31, which provides a steering force to turn the steering wheel 5. The steering actuator 31 includes a steering motor unit 32, a steering-side reducer 33, and a second pinion shaft 34. The steering motor unit 32 includes a steering motor 35 and a steering control device 36 for controlling the steering motor 35. The steering motor 35 is connected to the second pinion shaft 34 via the steering-side reducer 33. The second pinion shaft 34 has second pinion teeth 34a, and the rack shaft 22 has second rack teeth 22b. The second pinion shaft 34 is connected to the rack shaft 22 through the meshing of the second pinion teeth 34a and the second rack teeth 22b. In other words, the second pinion shaft 34 and the rack shaft 22 constitute a second rack and pinion mechanism.

[0029] The motor torque of the steering motor 35 is transmitted to the second pinion shaft 34 via the steering-side reducer 33. The torque transmitted to the second pinion shaft 34 is converted into the reciprocating motion of the rack shaft 22 via the second rack and pinion mechanism. As a result, the steering actuator 31 imparts steering force to the steering unit 6.

[0030] In the steering control device 2 configured as described above, steering force is applied from the steering actuator 31 by the driver's steering operation. As a result, the rack shaft 22 reciprocates, and the steering angle of the steering wheel 5 is changed. At this time, an operating reaction force is applied to the steering wheel 3 from the reaction force actuator 12 to resist the driver's steering operation.

[0031] Next, the electrical structure of the steering control device 2 will be explained.

[0032] like Figure 1 and Figure 2 As shown, the reaction force control device 16 and the steering control device 36 are communicatively connected. Various sensor detection results are input to the reaction force control device 16 and the steering control device 36. These sensors include, for example, the vehicle speed sensor 41, the voltage sensor 42, and the rotation angle sensor 43 of the reaction force motor 15 (described later). Other sensors include, for example, the rotation angle sensor of the steering motor 35 (not shown), and a torque sensor.

[0033] Vehicle speed sensor 41 detects the vehicle's speed, i.e., vehicle speed SP. Voltage sensor 42 detects the power supply voltage Vb of external power supply 45. External power supply 45 is a secondary battery installed in the vehicle. Rotation angle sensor 43 of reaction motor 15 detects the rotation angle θs of the rotation shaft of reaction motor 15 within a 360° range. Rotation angle sensor of steering motor 35 detects the rotation angle of the rotation shaft of steering motor 35 within a relative angle range. Torque sensor detects the steering torque applied to steering shaft 11.

[0034] The reaction force control device 16 calculates the target value of the reaction force, i.e., the reaction force control quantity, based on the detection results of the various sensors mentioned above. Based on the reaction force control quantity, the reaction force control device 16 controls the power supply to the reaction force motor 15. The steering control device 36 calculates the target value of the steering force, i.e., the steering control quantity, based on the detection results of the various sensors mentioned above. Based on the steering control quantity, the steering control device 36 controls the power supply to the steering motor 35. The power supplied to the reaction force motor 15 and the power supplied to the steering motor 35 are respectively supplied from an external power source 45 via the auxiliary power supply unit 1.

[0035] Next, the structure of the auxiliary power supply unit 1 and the motor units 13 and 32, which are the power supply objects of the auxiliary power supply unit 1, will be described.

[0036] (Reaction motor unit 13)

[0037] like Figure 2 As shown, the reaction force motor 15 of the reaction force motor unit 13 includes a rotor 51 and a first coil group 52a and a second coil group 52b wound on a stator (not shown). As an example, the reaction force motor 15 is a three-phase surface magnet synchronous motor. The first coil group 52a and the second coil group 52b each have three-phase coils of U, V, and W, respectively. The reaction force control device 16 includes a first drive circuit 53a, a second drive circuit 53b, and a reaction force control unit 54 that controls the first drive circuit 53a and the second drive circuit 53b. The reaction force control unit 54 includes a central processing unit (CPU) (not shown) and a memory. Various controls of the reaction force control unit 54 are executed by the CPU executing a program stored in the memory each predetermined operating cycle. As an example, the first drive circuit 53a and the second drive circuit 53b are typical PWM inverters with multiple switching elements.

[0038] The first coil group 52a is connected to the first drive circuit 53a via the first connecting line 55a. The second coil group 52b is connected to the second drive circuit 53b via the second connecting line 55b. Thus, power is supplied independently to the first coil group 52a and the second coil group 52b. In other words, the reaction force motor unit 13 has multiple power supply systems. As an example, it is required that the operating reaction force generated by the reaction force motor 15 is provided by half of the torque generated through the first coil group 52a and half of the torque generated through the second coil group 52b.

[0039] A first power supply system supplying power to the first coil group 52a includes a first drive circuit 53a and a first connecting line 55a. A second power supply system supplying power to the second coil group 52b includes a second drive circuit 53b and a second connecting line 55b. Furthermore, in Figure 2 For ease of explanation, the first connecting line 55a and the second connecting line 55b of each phase are combined into one diagram.

[0040] In calculating the aforementioned reaction force control quantity, the reaction force control unit 54 calculates the steering speed ωh of the steering wheel 3 and outputs it to the auxiliary power supply unit 1. Specifically, the rotation angle θs of the reaction force motor 15 detected by the rotation angle sensor 43 is input to the reaction force control unit 54. The reaction force control unit 54 calculates the accumulated angle, for example, by counting the rotational speed of the reaction force motor 15 from the steering midpoint and accumulating the rotation angle θs with the steering midpoint as the origin. Furthermore, the steering midpoint is the steering angle θh when the steering wheel 3 is at the center of the steering range. Next, the reaction force control unit 54 calculates the steering angle θh by multiplying the accumulated angle by a conversion factor based on the rotational speed ratio of the reaction force side reducer 14. Then, the steering speed ωh is calculated by differentiating the steering angle θh.

[0041] (Steering motor unit 32)

[0042] The steering motor unit 32 is configured similarly to the reaction force motor unit 13. Specifically, the steering motor 35 includes a rotor 61 and a first coil group 62a and a second coil group 62b wound around a stator (not shown). The steering control device 36 includes a first drive circuit 63a, a second drive circuit 63b, and a steering control unit 64 that controls the first drive circuit 63a and the second drive circuit 63b. Furthermore, the first coil group 62a is connected to the first drive circuit 63a via a first connecting line 65a, and the second coil group 62b is connected to the second drive circuit 63b via a second connecting line 65b. In other words, the steering motor unit 32 has multiple power supply systems.

[0043] A first power supply system supplying power to the first coil group 62a includes a first drive circuit 63a and a first connecting line 65a. A second power supply system supplying power to the second coil group 62b includes a second drive circuit 63b and a second connecting line 65b. Furthermore, in Figure 2 For ease of explanation, the first connecting line 65a and the second connecting line 65b of each phase are combined into one diagram.

[0044] (Auxiliary power supply unit 1)

[0045] The auxiliary power supply unit 1 supplies power from the external power supply 45 to the motor units 13 and 32. The auxiliary power supply unit 1 includes an auxiliary power supply device 71 and a downstream power supply line group 72.

[0046] The auxiliary power supply unit 71 is located midway through the power supply path from the external power source 45 to the motor units 13 and 32. The power supply path includes an upstream power supply line group 73 connecting the external power source 45 to the auxiliary power supply unit 71, a downstream power supply line group 72 connecting the auxiliary power supply unit 71 to the motor units 13 and 32, and an intermediate power supply line group 74 within the auxiliary power supply unit 71 (described later). In other words, the downstream power supply line group 72 constitutes part of the power supply path. Furthermore, there are cases where the structure including the auxiliary power supply unit 1, the reaction force control device 16, and the steering control device 36 is considered as a power system.

[0047] The upstream power supply line group 73 includes an upstream control line 81, an upstream drive line 82, and an upstream ground line 83. The upstream drive line 82 and the upstream control line 81 respectively connect the auxiliary power supply unit 71 to the high-potential terminal of the external power supply 45. A relay switch 84, which is switched on and off according to the vehicle's start switch, is provided midway along the upstream control line 81. As an example, the start switch is an ignition switch. The upstream ground line 83 grounds the auxiliary power supply unit 71.

[0048] The downstream power supply line group 72 includes a first downstream drive line 91a, a second downstream drive line 91b, and a downstream control line 92. The first downstream drive line 91a connects the auxiliary power supply device 71 to the respective first power supply systems of the reaction force motor unit 13 and the steering motor unit 32. That is, the first downstream drive line 91a connects the auxiliary power supply device 71 to the first drive circuits 53a and 63a. The second downstream drive line 91b connects the auxiliary power supply device 71 to the respective second power supply systems of the reaction force motor unit 13 and the steering motor unit 32. That is, the second downstream drive line 91b connects the auxiliary power supply device 71 to the second drive circuits 53b and 63b. The downstream control line 92 connects the auxiliary power supply device 71 to the reaction force control unit 54 and the steering control unit 64.

[0049] The auxiliary power supply unit 71 receives detection results from various sensors, including a vehicle speed sensor 41 and a voltage sensor 42. In other words, the auxiliary power supply unit 71 receives the vehicle speed SP and the power supply voltage Vb. Additionally, the steering speed ωh is input from the reaction force control unit 54 to the auxiliary power supply unit 71. Based on these status variables, the auxiliary power supply unit 71 supplies power to the motor units 13 and 32.

[0050] Next, the structure of the auxiliary power supply unit 71 and the downstream power supply line group 72 will be described in detail.

[0051] (Auxiliary power supply device 71)

[0052] like Figure 3As shown, the auxiliary power supply device 71 includes an intermediate power supply line group 74, which interconnects the upstream power supply line group 73 and the downstream power supply line group 72. The intermediate power supply line group 74 includes an intermediate control line 101 connected to the upstream control line 81, an intermediate drive line 102 connected to the upstream drive line 82, and an intermediate ground line 103 connected to the upstream ground line 83. Furthermore, the auxiliary power supply device 71 includes an auxiliary power supply 111, an auxiliary power supply control unit 112, a regulator 113, a switching circuit 114, a buck circuit 115, a boost circuit 116, an internal selection circuit 117, and an external selection circuit 118. These various circuits are connected to their corresponding lines. In the following description, the side of the intermediate power supply line group 74 connected to the upstream power supply line group 73 is referred to as the upstream side, and the opposite side is referred to as the downstream side.

[0053] In detail, the intermediate control line 101 has an internal intermediate control line 121 connected to the regulator 113, and an external intermediate control line 122 branching off from the internal intermediate control line 121. The external intermediate control line 122 is connected to the downstream control line 92.

[0054] The regulator 113 adjusts the power supply voltage Vb supplied from the external power supply 45 to a preset control voltage. An auxiliary power control unit 112 is connected to the regulator 113.

[0055] The auxiliary power control unit 112 operates based on the voltage supplied from the regulator 113. The auxiliary power control unit 112 includes a central processing unit (CPU) (not shown) and a memory. Various controls of the auxiliary power control unit 112 are executed by the CPU executing programs stored in the memory each predetermined operation cycle. Vehicle speed SP, power supply voltage Vb, and steering speed ωh are input to the auxiliary power control unit 112. Based on these state quantities, the auxiliary power control unit 112 controls various circuits, including the switching circuit 114 provided within the auxiliary power device 71. In other words, the auxiliary power control unit 112 is equivalent to a switching control circuit. Furthermore, for ease of explanation, the lines of signals output from the auxiliary power control unit 112 are not shown. The specific control method will be described later.

[0056] An auxiliary power supply 111 and a switching circuit 114 are configured between the intermediate drive line 102 and the intermediate ground line 103. The auxiliary power supply 111 assists in supplying power from the external power supply 45 to the motor units 13 and 32. The auxiliary power supply 111 is a capacitor that functions similarly to a secondary battery. As an example, the auxiliary power supply 111 is a lithium-ion capacitor.

[0057] The switching circuit 114 is configured to switch the power supply path, that is, the connection state of the auxiliary power supply 111 relative to the intermediate drive line 102 and the intermediate ground line 103. The connection states of the auxiliary power supply 111 include a charging state, a standby state, and a boost state. The charging state is the state in which the auxiliary power supply 111 is connected in parallel with the motor units 13 and 32 to the external power supply 45. The standby state is the state in which the auxiliary power supply 111 is disconnected from the external power supply 45 and connected to the motor units 13 and 32. The boost state is the state in which the auxiliary power supply 111 is connected in series with the external power supply 45 between the external power supply 45 and the motor units 13 and 32.

[0058] Specifically, the switching circuit 114 includes a boost line 131, a charging line 132, an output line 133, and a first switch 134 to a fifth switch 138. One end of the boost line 131 is connected to the intermediate drive line 102, and the other end is connected to the intermediate ground line 103. One end of the charging line 132 is connected to the intermediate drive line 102 at a connection point located downstream of the connection point of the boost line 131, and the other end is connected to the high-potential terminal of the auxiliary power supply 111. One end of the output line 133 is connected to the intermediate drive line 102 at a connection point located downstream of the connection point of the charging line 132, and the other end is connected to the high-potential terminal of the auxiliary power supply 111. The low-potential terminal of the auxiliary power supply 111 is connected to the intermediate ground line 103 at a connection point located downstream of the connection point of the boost line 131.

[0059] The first switch 134 is located on the intermediate grounding wire 103, near the upstream side of the connection point of the boost line 131. The second switch 135 is located midway through the boost line 131. The third switch 136 is located midway through the charging line 132. The fourth switch 137 is located midway through the output line 133. The fifth switch 138 is located on the intermediate drive line 102, between the connection point of the charging line 132 and the connection point of the output line 133.

[0060] Therefore, when the third switch 136 and the fifth switch 138 are on, and the first switch 134, the second switch 135, and the fourth switch 137 are off, the auxiliary power supply 111 is in a charging state. When the first switch 134 and the fourth switch 137 are on, and the second switch 135, the third switch 136, and the fifth switch 138 are off, the auxiliary power supply 111 is in a standby state. When the second switch 135 and the fourth switch 137 are on, and the first switch 134, the third switch 136, and the fifth switch 138 are off, the auxiliary power supply 111 is in a boost state.

[0061] A step-down circuit 115 is positioned on the charging line 132 between the third switch 136 and the auxiliary power supply 111. As an example, the step-down circuit 115 is a DC-DC converter. The step-down circuit 115 is configured to change the ratio of the output voltage to the input voltage within a specified range by adjusting the ratio of the internal switches being turned on and off. The step-down circuit 115 steps down the power supply voltage Vb input from the external power supply 45 to a preset charging output voltage and outputs it.

[0062] The boost circuit 116 is positioned on the intermediate drive line 102, closer to the downstream side than the connection point of the output line 133. As an example, the boost circuit 116 is a DC-DC converter. The boost circuit 116 is configured to change the ratio of the output voltage to the input voltage within a specified range by adjusting the ratio of the internal switches. In other words, the maximum output voltage that the boost circuit 116 can output depends on the magnitude of the input voltage. The boost circuit 116 boosts the input voltage according to the connection state of the auxiliary power supply 111.

[0063] Specifically, when the auxiliary power supply 111 is in charging or standby mode, the auxiliary power supply control unit 112 boosts the input voltage to a preset normal output voltage and outputs it. When the auxiliary power supply 111 is in boost mode, the auxiliary power supply control unit 112 boosts the input voltage to a preset boost output voltage and outputs it. The boost output voltage is preset to be such that if it is not greater than the normal output voltage and is greater than the power supply voltage Vb when the input voltage is normal, then the boost circuit 116 cannot boost the voltage.

[0064] The intermediate drive line 102 has an internal spare line 141 and an external spare line 142 connected to the downstream side of the boost circuit 116. The internal spare line 141 is connected to the regulator 113 via an internal intermediate control line 121. The external spare line 142 is connected to the external intermediate control line 122.

[0065] An internal selection circuit 117 is configured to span the internal spare line 141 and the internal intermediate control line 121. The internal selection circuit 117 includes a diode 143 and a backup switch 144. The diode 143 is positioned on the internal intermediate control line 121 such that it is closer to the downstream side than the connection point of the external intermediate control line 122 and closer to the upstream side than the connection point of the internal spare line 141. The diode 143 allows the flow of power from the upstream side to the downstream side and restricts the flow of power from the downstream side to the upstream side. The backup switch 144 is located midway along the internal spare line 141. The backup switch 144 is controlled by the auxiliary power supply control unit 112 according to the connection state of the auxiliary power supply 111. Specifically, when the auxiliary power supply 111 is in a charging state or a boost state, the backup switch 144 is disconnected. When the auxiliary power supply 111 is in a standby state, the backup switch 144 is turned on.

[0066] An external selection circuit 118 is configured to span the external spare line 142 and the external intermediate control line 122. The external selection circuit 118 includes selection switches 145 and 146. Selection switch 145 is positioned on the external intermediate control line 122 closer to the upstream side than the connection point of the external spare line 142. Selection switch 146 is positioned midway along the external spare line 142. Selection switches 145 and 146 are controlled by the auxiliary power control unit 112 based on the connection state of the auxiliary power supply 111. Specifically, when the auxiliary power supply 111 is in a charging or boosting state, selection switch 145 is turned on and selection switch 146 is turned off. When the auxiliary power supply 111 is in a standby state, selection switch 145 is turned off and selection switch 146 is turned on. In other words, selection switches 145 and 146 are turned on and off complementaryly.

[0067] The intermediate drive line 102 branches into two branches closer to the downstream side than the connection point of the external spare line 142, i.e., closer to the downstream side than the boost circuit 116. Thus, the intermediate drive line 102 has a first intermediate drive line 151 and a second intermediate drive line 152. No circuit elements for actively changing the voltage are provided in the first intermediate drive line 151 and the second intermediate drive line 152. Therefore, the potential at the downstream end of the first intermediate drive line 151 is approximately equal to the potential at the downstream end of the second intermediate drive line 152. The first intermediate drive line 151 is connected to the first downstream drive line 91a, and the second intermediate drive line 152 is connected to the second downstream drive line 91b. In other words, the intermediate drive line 102 has only wiring for transmitting power between the boost circuit 116 and the respective upstream ends of the first downstream drive line 91a and the second downstream drive line 91b.

[0068] (Downstream power supply line group 72)

[0069] The first downstream drive line 91a branches into two downstream branches. Thus, the first downstream drive line 91a has two branch first downstream drive lines 161 and 162. In other words, the branch first downstream drive lines 161 and 162 converge into one upstream branch. The branch first downstream drive lines 161 and 162 are respectively equivalent to discrete power supply lines. The downstream end of the branch first downstream drive line 161 is connected to the first drive circuit 53a of the reaction force motor unit 13. The downstream end of the branch first downstream drive line 162 is connected to the first drive circuit 63a of the steering motor unit 32. The upstream end of the first downstream drive line 91a is connected to the first intermediate drive line 151 as described above. That is, the upstream ends of the respective branch first downstream drive lines 161 and 162 are connected to the power supply path closer to the downstream side than the auxiliary power supply 111. Specifically, when the switching circuit 114 is in boost mode or standby mode, the upstream ends of the respective first downstream drive lines 161 and 162 are located closer to the downstream side than the auxiliary power supply 111. When the switching circuit 114 is in charging mode, the upstream ends of the respective first downstream drive lines 161 and 162 are located closer to the downstream side than the connection point of the charging line 132 in the intermediate drive line 102. Therefore, power is supplied to the first drive circuits 53a and 63a from the intermediate drive line 102, which is closer to the downstream side than the boost circuit 116, without passing through other circuit elements, only through the first intermediate drive line 151 and the first downstream drive line 91a.

[0070] The second downstream drive line 91b branches into two downstream branches. Thus, the second downstream drive line 91b has two branch second downstream drive lines 163 and 164. In other words, the branch second downstream drive lines 163 and 164 converge into one upstream branch. The branch second downstream drive lines 163 and 164 are respectively equivalent to separate power supply lines. The downstream end of the branch second downstream drive line 163 is connected to the second drive circuit 53b of the reaction force motor unit 13. The downstream end of the branch second downstream drive line 164 is connected to the second drive circuit 63b of the steering motor unit 32. The upstream end of the second downstream drive line 91b is connected to the second intermediate drive line 152 as described above. That is, the respective upstream ends of the branch second downstream drive lines 163 and 164 are connected to the power supply path closer to the downstream side than the connection point of the auxiliary power supply 111. Specifically, when the switching circuit 114 is in boost mode or standby mode, the upstream ends of the respective second downstream drive lines 163 and 164 are located closer to the downstream side than the auxiliary power supply 111. When the switching circuit 114 is in charging mode, the upstream ends of the respective second downstream drive lines 163 and 164 are located closer to the downstream side than the connection point of the charging line 132 in the intermediate drive line 102. Therefore, power is supplied to the second drive circuits 53b and 63b from the boost circuit 116 in the intermediate drive line 102, only via the second intermediate drive line 152 and the second downstream drive line 91b, without passing through other circuit elements.

[0071] The downstream control line 92 branches into two downstream branches. Thus, the downstream control line 92 has a reaction force control line 165 and a steering control line 166. In other words, the reaction force control line 165 and the steering control line 166 converge into one upstream branch. The downstream end of the reaction force control line 165 connects to the reaction force control unit 54. The downstream end of the steering control line 166 connects to the steering control unit 64. The upstream end of the downstream control line 92 connects to the external intermediate control line 122.

[0072] (Control of auxiliary power supply control unit 112)

[0073] When the external power supply 45 is normal and a large amount of power is supplied to the motor units 13 and 32, i.e., when the first or second condition is met, the auxiliary power supply control unit 112 controls the switching circuit 114 to make the connection state of the auxiliary power supply 111 a boost state. As an example, the auxiliary power supply control unit 112 determines that the external power supply 45 is normal when the power supply voltage Vb of the external power supply 45 is above the normal voltage threshold Vth. The normal voltage threshold Vth is the power supply voltage Vb that can be considered normal for the external power supply 45, and it is preset. The so-called large amount of power is power greater than the maximum power that can be supplied by the external power supply 45 in its normal state.

[0074] The first condition includes a vehicle speed SP below the driving judgment threshold SPth and a steering wheel 3 steering speed ωh above the steering operation execution judgment threshold ωth1. The driving judgment threshold SPth is a preset threshold representing when the vehicle is stopped or traveling at a very low speed. The steering operation execution judgment threshold ωth1 is a preset threshold representing the angular velocity of the steering wheel 3 as rotated by the driver's steering operation.

[0075] The second condition includes the steering speed ωh of the steering wheel 3 being greater than or equal to the high-speed steering judgment threshold ωth2. The high-speed steering judgment threshold ωth2, for example, represents the high-speed angular velocity of the steering wheel 3 as in an emergency steering maneuver to avoid an obstacle while the vehicle is in motion. The high-speed steering judgment threshold ωth2 is preset to a value greater than the steering execution judgment threshold ωth1.

[0076] When the external power supply 45 is normal and neither the first nor the second condition is met, the auxiliary power supply control unit 112 controls the switching circuit 114 to switch the auxiliary power supply 111 to a charging state. When the external power supply 45 is abnormal, the auxiliary power supply control unit 112 controls the switching circuit 114 to switch the auxiliary power supply 111 to a standby state.

[0077] Next, according to Figure 4 The flowchart describes the processing steps performed by the auxiliary power control unit 112 to determine the connection status of the auxiliary power supply 111.

[0078] Specifically, if the auxiliary power supply control unit 112 acquires various status quantities (step S1), it determines whether the power supply voltage Vb is above the normal voltage threshold Vth (step S2). If the power supply voltage Vb is below the normal voltage threshold Vth (step S2: no), the connection state of the auxiliary power supply 111 is changed to standby state (step S3).

[0079] On the other hand, if the power supply voltage Vb is above the normal voltage threshold Vth (step S2: Yes), the auxiliary power supply control unit 112 determines whether the steering speed ωh is above the steering execution determination threshold ωth1 (step S4). If the steering speed ωh is above the steering execution determination threshold ωth1 (step S4: Yes), it determines whether the vehicle speed SP is below the driving determination threshold SPth (step S5). If the vehicle speed SP is below the driving determination threshold SPth (step S5: Yes), since the external power supply 45 is normal and the first condition is met, the connection state of the auxiliary power supply 111 is set to boost state (step S6).

[0080] If the vehicle speed SP is greater than the driving determination threshold SPth (step S5: No), the auxiliary power control unit 112 determines whether the steering operation speed ωh is greater than or equal to the high-speed steering operation determination threshold ωth2 (step S7). Then, if the steering operation speed ωh is greater than or equal to the high-speed steering operation determination threshold ωth2 (step S7: Yes), since the external power supply 45 is normal and the second condition is met, the process moves to step S6, and the connection state of the auxiliary power supply 111 is changed to a boost state.

[0081] In contrast, if the steering speed ωh is less than the steering operation determination threshold ωth1 (step S4: No), or if the steering speed ωh is less than the high-speed steering determination threshold ωth2 (step S7: No), the auxiliary power control unit 112 sets the connection state of the auxiliary power supply 111 to the charging state (step S8).

[0082] (Power supply method to reaction force motor unit 13 and steering motor unit 32)

[0083] Next, the power supply methods of motor units 13 and 32 will be explained according to the connection status of each auxiliary power supply 111.

[0084] like Figure 5As shown, when the auxiliary power supply 111 is in a charging state, the power supply voltage Vb of the external power supply 45 is input to the boost circuit 116 via the intermediate drive line 102. The normally used output voltage from the boost circuit 116 is output to the first downstream drive line 91a via the first intermediate drive line 151, and to the second downstream drive line 91b via the second intermediate drive line 152. Furthermore, the normally used output voltage output to the first downstream drive line 91a is supplied to the first drive circuit 53a of the reaction force control device 16 via the branch first downstream drive line 161, and to the first drive circuit 63a of the steering control device 36 via the branch first downstream drive line 162. The normally used output voltage output to the second downstream drive line 91b is supplied to the second drive circuit 53b of the reaction force control device 16 via the branch second downstream drive line 163, and to the second drive circuit 63b of the steering control device 36 via the branch second downstream drive line 164.

[0085] In the charging state, the output voltage for charging is supplied from the step-down circuit 115 to the auxiliary power supply 111 via the charging line 132. Therefore, the auxiliary power supply 111 remains in a charging state. When the auxiliary power supply 111 is in a charging state, since the standby switch 144 is open, power is supplied to the auxiliary power supply control unit 112 via the upstream control line 81 and the internal intermediate control line 121. In addition, since the selector switch 145 is turned on and the selector switch 146 is turned off, the power supply voltage Vb supplied from the upstream control line 81 is output to the downstream control line 92 via the external intermediate control line 122. Moreover, the power supply voltage Vb output to the downstream control line 92 is supplied to the reaction force control unit 54 via the reaction force control line 165 and to the steering control unit 64 via the steering control line 166.

[0086] Next, as Figure 6 As shown, in the event of an abnormality in the external power supply 45, the auxiliary power supply 111 becomes a standby state. In this case, no power is supplied from the external power supply 45 to the auxiliary power supply device 71. Instead of the power supply voltage Vb of the external power supply 45, the voltage of the auxiliary power supply 111 is input to the boost circuit 116 via the output line 133. The boost circuit 116 boosts the voltage of the auxiliary power supply 111 and outputs a normally used output voltage. The output voltage output from the boost circuit 116 is supplied to the first drive circuits 53a, 63a and the second drive circuits 53b, 63b in the same manner as in the charging state. Thus, even without power from the external power supply 45, power can be temporarily supplied to the motor units 13, 32, allowing the application of operating reaction force and the steering of the steering wheel 5 to continue.

[0087] In standby mode, power is supplied to the auxiliary power control unit 112 via the intermediate drive line 102 and the internal backup line 141 because the backup switch 144 is turned on. Additionally, the voltage output from the intermediate drive line 102 is output to the downstream control line 92 via the external backup line 142 and the external intermediate control line 122 because the selector switch 145 is turned off and the selector switch 146 is turned on. The power supply voltage Vb output to the downstream control line 92 is supplied to the reaction force control unit 54 and the steering control unit 64 in the same manner as in the charging state.

[0088] Next, as Figure 7 As shown, when the auxiliary power supply 111 is connected in boost mode, the power supply voltage Vb of the external power supply 45 is not input to the boost circuit 116, but is input to the low-potential terminal of the auxiliary power supply 111 via the intermediate drive line 102, the boost line 131, and the intermediate ground line 103. That is, the external power supply 45 and the auxiliary power supply 111 are connected in series. Furthermore, the total voltage obtained by adding the voltage of the auxiliary power supply 111 to the power supply voltage Vb of the external power supply 45 is input to the boost circuit 116. The boost circuit 116 boosts this total voltage and outputs a boost output voltage that is larger than the normally used output voltage. The output voltage output from the boost circuit 116 is supplied to the first drive circuits 53a, 63a and the second drive circuits 53b, 63b in the same manner as in the charging state. Therefore, a larger amount of power can be supplied to the motor units 13, 32.

[0089] In the boosted state, the backup switch 144 is disconnected in the same way as in the charging state. Similarly, when the auxiliary power supply 111 is in the boosted state, the selector switch 145 is turned on and the selector switch 146 is turned off, just as in the charging state. Therefore, power is supplied to the auxiliary power control unit 112, the reaction force control unit 54, and the steering control unit 64 in the same way as in the charging state.

[0090] As described above, the magnitude of the output voltage from the boost circuit 116 varies depending on the connection state of the auxiliary power supply 111, but approximately equal voltages are supplied to the first drive circuits 53a and 63a and the second drive circuits 53b and 63b. That is, since approximately equal power is supplied to the first coil group 52a and the second coil group 52b of the reaction force motor 15, the reaction force motor 15 is driven stably. Similarly, since approximately equal voltages are supplied to the first coil group 62a and the second coil group 62b of the steering motor 35, the steering motor 35 is driven stably.

[0091] Next, the function and effects of this implementation method will be explained.

[0092] (1) The auxiliary power supply unit 1 includes an auxiliary power supply device 71 disposed midway in the power supply path from an external power supply 45 to the motor units 13 and 32, and a downstream power supply line group 72 connecting the auxiliary power supply device 71 to the motor units 13 and 32. The auxiliary power supply device 71 includes an auxiliary power supply 111 that assists in the power supply from the external power supply 45 to the motor units 13 and 32, and a switching circuit 114 configured to switch the connection state of the auxiliary power supply 111 relative to the power supply path. The connection state of the auxiliary power supply 111 that can be switched by the switching circuit 114 includes a boost state. The downstream power supply line group 72 includes branch first downstream drive lines 161 and 162, and branch second downstream drive lines 163 and 164. The upstream ends of the respective branch first downstream drive lines 161 and 162 and branch second downstream drive lines 163 and 164 are connected to the power supply path closer to the downstream side than the auxiliary power supply 111.

[0093] By switching the auxiliary power supply 111 to a boost state, the auxiliary power supply device 71 outputs a boosted output voltage based on the voltage obtained by adding the voltage of the auxiliary power supply 111 to the power supply voltage Vb of the external power supply 45. This supplies a larger power based on the boosted output voltage to each of the first and second power supply systems of the reaction motor unit 13, and to each of the first and second power supply systems of the steering motor unit 32. Since a larger power supply can be temporarily provided to the motor units 13 and 32 using the power of the auxiliary power supply 111, larger power demands can be met even without using a large-capacity external power supply 45.

[0094] (2) The intermediate drive line 102 has only wiring for transmitting power between the boost circuit 116 and the respective upstream ends of the first downstream drive line 91a and the second downstream drive line 91b. Therefore, a larger amount of power can be supplied to each power supply system of the motor units 13 and 32 based on approximately equal boost output voltages. As a result, power supply discrepancies to each power supply system can be suppressed, enabling the motor units 13 and 32 to operate stably.

[0095] (3) Since the connection state of the auxiliary power supply 111, which can be switched by the switching circuit 114, includes a charging state, the auxiliary power supply 111 can be charged by the external power supply 45. As a result, the connection state of the auxiliary power supply 111 is repeatedly changed to a boost state, which can supply a large amount of power to the motor units 13 and 32.

[0096] (4) The connection state of the auxiliary power supply 111, which can be switched by the switching circuit 114, includes a standby state. Therefore, in the event of an abnormality in the external power supply 45, the motor units 13 and 32 can continue to be driven by supplying power from the auxiliary power supply 111.

[0097] (5) When the external power supply 45 is normal and the first condition described above is met, the auxiliary power supply control unit 112 sets the connection state of the auxiliary power supply 111 to a boost state. Therefore, for example, when a large amount of power is required by performing static operation, a large amount of power can be supplied to the motor units 13 and 32.

[0098] (6) When the external power supply 45 is normal and the second condition described above is met, the auxiliary power supply control unit 112 sets the connection state of the auxiliary power supply 111 to a boost state. Therefore, for example, when a larger amount of power is required by performing emergency steering, a larger amount of power can be supplied to the motor units 13 and 32.

[0099] (Second Implementation)

[0100] Next, a second embodiment of the auxiliary power supply unit, the control method of the auxiliary power supply unit, and the steering control device will be described with reference to the accompanying drawings. Furthermore, for ease of explanation, the same reference numerals are used for the same structures as in the first embodiment described above, and their descriptions are omitted.

[0101] like Figure 8 As shown, in the vehicle equipped with the auxiliary power supply unit 1 and the steering control device 2, there are two power supplies, a first power supply 201a and a second power supply 201b, which serve as external power sources. Therefore, the power supply path includes a first power supply path that supplies power from the first power supply 201a to the motor units 13 and 32, and a second power supply path that supplies power from the second power supply 201b to the motor units 13 and 32. The auxiliary power supply device 202 of the auxiliary power supply unit 1 is disposed midway along both the first and second power supply paths, spanning both sides of the first and second power supply paths.

[0102] The first power supply path includes a first upstream power supply line group 211a connecting the first power source 201a to the auxiliary power supply device 202, a first downstream power supply line group 212a connecting the auxiliary power supply device 202 to the motor units 13 and 32, and a first intermediate power supply line group 74a within the auxiliary power supply device 202 (described later). That is, the first downstream power supply line group 212a constitutes part of the first power supply path. The second power supply path includes a second upstream power supply line group 211b connecting the second power source 201b to the auxiliary power supply device 202, a second downstream power supply line group 212b connecting the auxiliary power supply device 202 to the motor units 13 and 32, and a second intermediate power supply line group 74b within the auxiliary power supply device 202 (described later). That is, the second downstream power supply line group 212b constitutes part of the second power supply path.

[0103] The first upstream power supply line group 211a includes a first upstream control line 221a, a first upstream drive line 222a, and a first upstream ground line 223a. The first upstream drive line 222a and the first upstream control line 221a respectively connect the auxiliary power supply device 202 to the high-potential terminal of the first power supply 201a. A first relay switch 224a, which is switched on and off according to the vehicle's start switch, is provided midway along the first upstream control line 221a. The first upstream ground line 223a grounds the auxiliary power supply device 202.

[0104] The second upstream power supply line group 211b includes a second upstream control line 221b, a second upstream drive line 222b, and a second upstream ground line 223b. The second upstream drive line 222b and the second upstream control line 221b respectively connect the auxiliary power supply device 202 to the high-potential terminal of the second power supply 201b. A second relay switch 224b, which is switched on and off according to the vehicle's start switch, is provided midway along the second upstream control line 221b. The second upstream ground line 223b grounds the auxiliary power supply device 202.

[0105] The first downstream power supply line group 212a includes the first downstream drive line 91a and the first downstream control line 232a described in the first embodiment. The first downstream drive line 91a connects the first power supply systems of the auxiliary power supply device 202, the reaction force motor unit 13, and the steering motor unit 32. The first downstream control line 232a connects the auxiliary power supply device 202 and the reaction force control unit 54. The branches of the first downstream drive line 91a, the first downstream drive lines 161 and 162, respectively correspond to the first discrete power supply lines.

[0106] The second downstream power supply line group 212b includes the second downstream drive line 91b and the second downstream control line 232b described in the first embodiment. The second downstream drive line 91b connects to the second power supply systems of the auxiliary power supply unit 202, the reaction force motor unit 13, and the steering motor unit 32, respectively. The second downstream control line 232b connects to the auxiliary power supply unit 202 and the steering control unit 64. The branches of the second downstream drive line 91b, the second downstream drive lines 163 and 164, respectively correspond to the second discrete power supply lines.

[0107] In addition to the auxiliary power control unit 203 and the structure for supplying power to the auxiliary power control unit 203, the auxiliary power supply device 202 of this embodiment includes a first auxiliary power system and a second auxiliary power system configured substantially the same as the auxiliary power supply device 71 of the first embodiment. The first auxiliary power system supplies power from the first power supply 201a to the respective first power supply systems of the reaction force motor unit 13 and the steering motor unit 32, as well as to the reaction force control unit 54. The second auxiliary power system supplies power from the second power supply 201b to the respective second power supply systems of the reaction force motor unit 13 and the steering motor unit 32, as well as to the steering control unit 64. The first auxiliary power system is disposed between the first upstream power supply line group 211a and the first downstream power supply line group 212a, and the second auxiliary power system is disposed between the second upstream power supply line group 211b and the second downstream power supply line group 212b.

[0108] Hereinafter, for the structure of the first auxiliary power system, repeated descriptions will be omitted by adding "first" to the beginning of the component names of each component of the auxiliary power device 71 in the first embodiment and adding "a" to the reference numerals indicating each component. Similarly, for the structure of the second auxiliary power system, repeated descriptions will be omitted by adding "second" to the beginning of the component names of each component of the auxiliary power device 71 in the first embodiment and adding "b" to the reference numerals indicating each component.

[0109] That is, the auxiliary power supply device 202 includes a first intermediate power supply line group 74a that connects the first upstream power supply line group 211a and the first downstream power supply line group 212a to each other, and a second intermediate power supply line group 74b that connects the second upstream power supply line group 211b and the second downstream power supply line group 212b to each other. The first intermediate power supply line group 74a includes a first intermediate control line 101a connected to the first upstream control line 221a, a first intermediate drive line 102a connected to the first upstream drive line 222a, and a first intermediate ground line 103a connected to the first upstream ground line 223a. The second intermediate power supply line group 74b includes a second intermediate control line 101b connected to the second upstream control line 221b, a second intermediate drive line 102b connected to the second upstream drive line 222b, and a second intermediate ground line 103b connected to the second upstream ground line 223b.

[0110] However, the first intermediate drive line 102a has a first external spare line 142a, but no first internal spare line. Therefore, the auxiliary power supply device 202 does not have a first internal selection circuit. Furthermore, the first intermediate drive line 102a may not branch at a point closer to the downstream side than the connection point of the first external spare line 142a. Similarly, the second intermediate drive line 102b has a second external spare line 142b, but no second internal spare line. Therefore, the auxiliary power supply device 202 does not have a second internal selection circuit. Furthermore, the second intermediate drive line 102b does not branch at a point closer to the downstream side than the connection point of the second external spare line 142b.

[0111] In addition to the auxiliary power control unit 203, the auxiliary power supply device 202 also includes a first auxiliary power supply 111a, a second auxiliary power supply 111b, a first regulator 113a, a second regulator 113b, a first switching circuit 114a, a second switching circuit 114b, a first buck circuit 115a, a second buck circuit 115b, a first boost circuit 116a, a second boost circuit 116b, a first external selection circuit 118a, and a second external selection circuit 118b. The first auxiliary power supply 111a, the first regulator 113a, the first switching circuit 114a, the first buck circuit 115a, the first boost circuit 116a, and the first external selection circuit 118a are connected to the lines corresponding to the first intermediate power supply line group 74a in the same manner as in the first embodiment described above. The second auxiliary power supply 111b, the second regulator 113b, the second switching circuit 114b, the second buck circuit 115b, the second boost circuit 116b, and the second external selection circuit 118b are connected to the lines corresponding to the second intermediate power supply line group 74b in the same manner as in the first embodiment described above.

[0112] The first downstream drive line 91a of the first downstream power supply line group 212a is connected to the first intermediate drive line 102a. That is, the upstream ends of the respective branch first downstream drive lines 161 and 162 are connected to the first intermediate drive line 102a in a manner that is closer to the downstream side than the first auxiliary power supply 111a, i.e., closer to the first boost circuit 116a. The upstream end of the first downstream control line 232a is connected to the first external intermediate control line 122a of the first intermediate control line 101a.

[0113] The second downstream drive line 91b of the second downstream power supply line group 212b is connected to the second intermediate drive line 102b. That is, the upstream ends of the respective branch second downstream drive lines 163 and 164 are connected to the second intermediate drive line 102b in a manner that is closer to the downstream side than the second auxiliary power supply 111b, i.e., closer to the downstream side than the second boost circuit 116b. The upstream end of the second downstream control line 232b is connected to the second external intermediate control line 101b via intermediate control line 122b.

[0114] The first regulator 113a and the second regulator 113b are respectively connected to the auxiliary power control unit 203. The auxiliary power control unit 203 operates based on the power supplied from at least one of the first regulator 113a and the second regulator 113b.

[0115] The auxiliary power control unit 203 receives inputs of vehicle speed SP, steering speed ωh, power supply voltage Vba of the first power supply 201a, and power supply voltage Vbb of the second power supply 201b. Furthermore, power supply voltage Vba is detected by the first voltage sensor 271a and the second voltage sensor 271b. Based on these state values, the auxiliary power control unit 203 controls various circuits, including the first switching circuit 114a, the second switching circuit 114b, the first boost circuit 116a, and the first boost circuit 116a, all located within the auxiliary power device 202. In other words, the auxiliary power control unit 203 functions as both the switching control circuit and the boost control circuit. For clarity, the signal lines output from the auxiliary power control unit 203 are not shown in the diagram.

[0116] The auxiliary power control unit 203 controls the connection state of the first auxiliary power supply 111a in the same way as the auxiliary power control unit 112 in the first embodiment, except that it uses the power supply voltage Vba of the first power supply 201a instead of the power supply voltage Vb of the external power supply 45. Similarly, the auxiliary power control unit 203 controls the connection state of the second auxiliary power supply 111b in the same way as the auxiliary power control unit 112 in the first embodiment, except that it uses the power supply voltage Vbb of the second power supply 201b instead of the power supply voltage Vb of the external power supply 45.

[0117] Furthermore, the auxiliary power supply control unit 203 controls the first boost circuit 116a and the second boost circuit 116b so that the normally used output voltage from the first boost circuit 116a and the normally used output voltage from the second boost circuit 116b are equal. Additionally, the auxiliary power supply control unit 203 controls the first boost circuit 116a and the second boost circuit 116b so that the boost output voltage from the first boost circuit 116a and the boost output voltage from the second boost circuit 116b are equal.

[0118] (Power supply method to reaction force motor unit 13 and steering motor unit 32)

[0119] Next, the power supply methods to the motor units 13 and 32 will be described according to each connection state of the first auxiliary power supply 111a and the second auxiliary power supply 111b.

[0120] like Figure 9 As shown, when both the first auxiliary power supply 111a and the second auxiliary power supply 111b are in a charging state, the power supply voltage Vba of the first power supply 201a is input to the first boost circuit 116a via the first intermediate drive line 102a, and the power supply voltage Vbb of the second power supply 201b is input to the second boost circuit 116b via the second intermediate drive line 102b. The normally used output voltage output from the first boost circuit 116a is input to the first downstream drive line 91a via the first intermediate drive line 102a, and the normally used output voltage output from the second boost circuit 116b is output to the second downstream drive line 91b via the second intermediate drive line 102b. Furthermore, the output voltage output to the first downstream drive line 91a is supplied to the first drive circuits 53a and 63a in the same manner as in the first embodiment described above. The output voltage output to the second downstream drive line 91b is supplied to the second drive circuits 53b and 63b in the same manner as in the first embodiment described above.

[0121] When both the first auxiliary power supply 111a and the second auxiliary power supply 111b are in a charging state, the first auxiliary power supply 111a is supplied with a charging output voltage from the first step-down circuit 115a via the first charging line 132a, and the second auxiliary power supply 111b is supplied with a charging output voltage from the second step-down circuit 115b via the second charging line 132b. Since the selection switch 145a of the first external selection circuit 118a is turned on and the selection switch 146a is turned off, the power supply voltage Vba supplied from the first upstream control line 221a is output to the first downstream control line 232a via the first external intermediate control line 122a and supplied to the reaction force control unit 54. In addition, since the selection switch 145b of the second external selection circuit 118b is turned on and the selection switch 146b is turned off, the power supply voltage Vbb supplied from the second upstream control line 221b is output to the second downstream control line 232b via the second external intermediate control line 122b and supplied to the steering control unit 64.

[0122] Next, as Figure 10 As shown, when the first power supply 201a malfunctions and the second power supply 201b is normal, the connection state of the first auxiliary power supply 111a becomes a standby state, and the connection state of the second auxiliary power supply 111b becomes a charging state. At this time, no power is supplied from the first power supply 201a to the auxiliary power supply device 202. On the other hand, the power supply voltage Vbb of the second power supply 201b is input to the second boost circuit 116b via the second intermediate drive line 102b. In this case, the power supply to the second drive circuits 53b and 63b and the steering control unit 64 is the same as in the charging state. In the first auxiliary power system, the power supply voltage Vba of the first auxiliary power supply 111a is input to the first boost circuit 116a via the first output line 133a. The normally used output voltage from the first boost circuit 116a is output to the first downstream drive line 91a via the first intermediate drive line 102a. The output voltage output to the first downstream drive line 91a is supplied to the first drive circuits 53a and 63a in the same way as in the charging state.

[0123] When the connection state of the first auxiliary power supply 111a is in standby mode, the selection switch 145a of the first external selection circuit 118a is turned off, and the selection switch 146a is turned on. Therefore, the voltage output from the first intermediate drive line 102a is output to the first downstream control line 232a via the first external standby line 142a and the first external intermediate control line 122a, and is supplied to the reaction force control unit 54.

[0124] Next, as Figure 11As shown, when the first power supply 201a is normal and the second power supply 201b malfunctions, the connection state of the first auxiliary power supply 111a becomes the charging state, and the connection state of the second auxiliary power supply 111b becomes the standby state. At this time, the power supply voltage Vba of the first power supply 201a is input to the first boost circuit 116a via the first intermediate drive line 102a, while no power is supplied from the second power supply 201b to the auxiliary power supply device 202. In this case, the power supply to the first drive circuits 53a and 63a and the reaction force control unit 54 is the same as in the charging state. In the second auxiliary power supply system, the voltage of the second auxiliary power supply 111b is input to the second boost circuit 116b via the second output line 133b. The normally used output voltage from the second boost circuit 116b is output to the second downstream drive line 91b via the second intermediate drive line 102b. The output voltage output to the second downstream drive line 91b is supplied to the second drive circuits 53b and 63b in the same way as in the charging state.

[0125] When the connection state of the second auxiliary power supply 111b is in standby mode, the selection switch 145b of the second external selection circuit 118b is turned off, and the selection switch 146b is turned on. Therefore, the voltage output from the second intermediate drive line 102b is output to the second downstream control line 232b via the second external standby line 142b and the second external intermediate control line 122b, and is supplied to the steering control unit 64.

[0126] Next, as Figure 12As shown, the case where both the first auxiliary power supply 111a and the second auxiliary power supply 111b are in boost mode will be explained. In this case, the power supply voltage Vba of the first power supply 201a is input to the low-potential terminal of the first auxiliary power supply 111a via the first intermediate drive line 102a, the first boost line 131a, and the first intermediate ground line 103a. The power supply voltage Vbb of the second power supply 201b is input to the low-potential terminal of the second auxiliary power supply 111b via the second intermediate drive line 102b, the second boost line 131b, and the second intermediate ground line 103b. That is, the first power supply 201a and the first auxiliary power supply 111a are connected in series, and the second power supply 201b and the second auxiliary power supply 111b are connected in series. Furthermore, the total voltage obtained by adding the voltage of the first auxiliary power supply 111a to the power supply voltage Vba of the first power supply 201a is input to the first boost circuit 116a. Therefore, a boost output voltage larger than the normally used output voltage is output from the first boost circuit 116a. Furthermore, the combined voltage obtained by adding the voltage of the second auxiliary power supply 111b to the power supply voltage Vbb of the second power supply 201b is input to the second boost circuit 116b. Therefore, the second boost circuit 116b outputs a boost output voltage that is larger than the normally used output voltage. Since these output voltages from the first boost circuit 116a and the second boost circuit 116b are supplied to the first drive circuits 53a and 63a and the second drive circuits 53b and 63b in the same manner as in the charging state, a larger power supply can be provided to the motor units 13 and 32.

[0127] When the connection states of the first auxiliary power supply 111a and the second auxiliary power supply 111b are in the boost state, power is supplied to the auxiliary power control unit 203, the reaction force control unit 54 and the steering control unit 64 in the same way as in the charging state.

[0128] In addition to the same functions and effects as those of (1), (3) to (6) in the first embodiment described above, this embodiment also has the following functions and effects.

[0129] (7) The first downstream power supply line group 212a includes branch first downstream drive lines 161 and 162 and branch second downstream drive lines 163 and 164. The upstream ends of each of the branch first downstream drive lines 161 and 162 are connected to the first intermediate drive line 102a closer to the downstream side than the first boost circuit 116a. The upstream ends of each of the branch second downstream drive lines 163 and 164 are connected to the second intermediate drive line 102b closer to the downstream side than the second boost circuit 116b. The auxiliary power control unit 203 controls the first boost circuit 116a and the second boost circuit 116b so that the boost output voltage from the first boost circuit 116a and the boost output voltage from the second boost circuit 116b are equal to each other. Therefore, based on the approximately equal boost output voltages, a larger amount of power can be supplied to each power supply system of the motor units 13 and 32. Therefore, deviations in the power supplied to each power supply system can be suppressed, enabling motor units 13 and 32 to operate stably.

[0130] The above embodiments can be modified and implemented as follows. The above embodiments and the following variations can be combined and implemented with each other to the extent that they are not technically contradictory.

[0131] In the second embodiment described above, the auxiliary power supply device 202 may replace the single auxiliary power supply control unit 203, and may include a first auxiliary power supply control unit for controlling the first auxiliary power supply system and a second auxiliary power supply control unit for controlling the second auxiliary power supply system.

[0132] In the second embodiment described above, the first boost circuit 116a and the second boost circuit 116b may not be controlled in a manner where the output voltage from the first boost circuit 116a and the output voltage from the second boost circuit 116b are not equal. In this case, the auxiliary power supply device 202 may not include the first boost circuit 116a and the second boost circuit 116b. Furthermore, in the first embodiment described above, the auxiliary power supply device 71 may not include the boost circuit 116.

[0133] In the second embodiment described above, the auxiliary power supply device 202 may also include: a first internal spare line and a first internal selection circuit that connect the first intermediate drive line 102a and the first internal intermediate control line 121a to each other; and a second internal spare line and a second internal selection circuit that connect the second intermediate drive line 102b and the second internal intermediate control line 121b to each other. In this configuration, even if an abnormality occurs in either the first power supply 201a or the second power supply 201b, the motor units 13 and 32 can continue to be driven.

[0134] In the second embodiment described above, the power supply to the reaction force control unit 54 and the steering control unit 64 can also be made redundant. Specifically, for example, the first downstream control line 232a can be branched into two downstream branches, and the auxiliary power supply unit 202 can be connected to the reaction force control unit 54 and the steering control unit 64 through the first downstream control line 232a. In addition, the second downstream control line 232b can be branched into two downstream branches, and the auxiliary power supply unit 202 can be connected to the reaction force control unit 54 and the steering control unit 64 through the second downstream control line 232b. Moreover, the wiring in the auxiliary power supply unit 202 can be controlled in such a way that when the first power supply 201a is normal, the connection between the second power supply 201b and the second downstream control line 232b is disconnected, and when the first power supply 201a is abnormal, the connection between the second power supply 201b and the second downstream control line 232b is connected.

[0135] • In the first embodiment described above, the auxiliary power supply device 71 may not include the step-down circuit 115. • In the second embodiment described above, the auxiliary power supply device 202 may not include the step-down circuits 115a and 115b.

[0136] In the first embodiment described above, the fifth switch 138 may also be positioned on the intermediate drive line 102 between the connection point of the boost line 131 and the connection point of the charging line 132. This modification can also be applied to the first switching circuit 114a and the second switching circuit 114b of the second embodiment.

[0137] In the first embodiment described above, a branch of the first downstream drive line 91a, the first downstream drive line 161, can be connected to the first drive circuit 53a of the reaction force motor unit 13, and a branch of the first downstream drive line 162 can be connected to the second drive circuit 53b of the reaction force motor unit 13. Alternatively, a branch of the second downstream drive line 91b, the second downstream drive line 163, can be connected to the first drive circuit 63a of the steering motor unit 32, and a branch of the second downstream drive line 164 can be connected to the second drive circuit 63b of the steering motor unit 32.

[0138] In the first embodiment described above, the intermediate drive line 102 branches into two lines closer to the downstream side than the connection point of the auxiliary power supply 111, but this is not a limitation; it may not branch at all. In this case, the first downstream drive line 91a constituting the downstream power supply line group 72 can, for example, have a structure with four branches to the downstream side. Alternatively, the intermediate drive line 102 may also have three or more branches closer to the downstream side than the connection point of the auxiliary power supply 111. In this case, the first downstream drive line 91a may, for example, have a structure without branches to the downstream side.

[0139] Similarly, in the second embodiment described above, the first intermediate drive line 102a may be branched into two or more branches closer to the downstream side than the first boost circuit 116a, and the second intermediate drive line 102b may be branched into two or more branches closer to the downstream side than the second boost circuit 116b.

[0140] In the first embodiment described above, the switching circuit 114 may be configured to switch the connection state of the auxiliary power supply 111 only to the boost state and the charging state, and not to the standby state. Alternatively, the switching circuit 114 may be configured to switch the connection state of the auxiliary power supply 111 only to the boost state and the standby state, and not to the charging state. In this case, the auxiliary power supply 111 may also be a primary battery. Furthermore, the switching circuit 114 may be configured to switch the connection state of the auxiliary power supply 111 only to states other than the boost state, the charging state, and the standby state, and not to the charging state or the standby state. As an example, another state is when the external power supply 45 is connected to the power source and the auxiliary power supply 111 is disconnected from the intermediate drive line 102. In this case, the auxiliary power supply 111 may also be a primary battery. This variation can also be applied to the first switching circuit 114a and the second switching circuit 114b.

[0141] • In the above embodiments, both the determination of whether the first condition is met and the determination of whether the second condition is met are performed. However, the system is not limited to this. The auxiliary power control units 112 and 203 may perform only one of the determinations. The auxiliary power control units 112 and 203 may also use conditions other than the first and second conditions as conditions for supplying a larger amount of power to the power supply object.

[0142] In the first embodiment described above, the auxiliary power supply 111 can be, for example, an electric double-layer capacitor (EDLC) or a lithium-ion battery (LIB). This variation can also be applied to the first auxiliary power supply 111a and the second auxiliary power supply 111b in the second embodiment described above.

[0143] In the above embodiments, the auxiliary power control units 112 and 203 control the various circuits in the auxiliary power devices 71 and 202. However, it is not limited to this. The auxiliary power devices 71 and 202 may not have the structure of the auxiliary power control units 112 and 203, and the various circuits may be controlled by an external control device (e.g., the reaction force control unit 54).

[0144] In the above embodiments, the reaction force control unit 54 controls both the first drive circuit 53a and the second drive circuit 53b, but is not limited to this. For example, the reaction force control device 16 may also include a first reaction force control unit that controls the first drive circuit 53a and a second reaction force control unit that controls the second drive circuit 53b. In this case, the first reaction force control unit may operate on command values ​​such as current and send command values ​​to the second reaction force control unit, which then operates according to the received command values. That is, it may also be configured as a master-slave control device where the first reaction force control unit is the master control unit and the second reaction force control unit is the slave control unit. Furthermore, this modification can also be applied to the steering control device 36.

[0145] In the above embodiments, the reaction force control unit 54 may also be configured as a processing circuit consisting of (1) one or more processors that operate according to a computer program (software), (2) one or more dedicated hardware circuits such as an application-specific integrated circuit (ASIC) that performs at least a portion of the various processes, or (3) a combination of these. This variation can also be applied to the steering control unit 64 and the auxiliary power control units 112 and 203. The processor includes a CPU and memories such as RAM and ROM, which store program code or instructions configured to cause the CPU to perform processes. Memory, i.e., non-transitory computer-readable medium, includes all available media accessible to general-purpose or special-purpose computers.

[0146] In the above embodiments, the steering control device 2 is a linkageless structure where the reaction force unit 4 and the steering unit 6 are mechanically and permanently separated, but it is not limited to this. For example, it can also be as follows: Figure 1 As indicated by the double-dotted line, the reaction force unit 4 and the steering unit can be mechanically separated via the clutch 301. Furthermore, the steering control device 2 is not limited to a steer-by-wire type; it can also be an electric power steering device that imparts torque to the auxiliary motor unit on the steering shaft 11 or rack shaft 22. In this case, the auxiliary motor unit, as the power source, has multiple power supply systems.

[0147] In the above embodiments, the power supply is not limited to a motor unit in which the motor and control device are integrated, but may also be a motor separately provided from the control device. Furthermore, it is not limited to a motor that serves as the drive source for the steering control device 2; for example, it may also be a motor used as a driving drive source in an electric vehicle. Moreover, for example, an airbag device, a braking device, or any device mounted outside the vehicle may be used as the power supply.

Claims

1. An auxiliary power supply unit, which supplies power from an external power source to a power supply object having multiple power supply systems, comprising: An auxiliary power supply device is disposed midway in the power supply path from the external power source to the object being powered; and The power supply line assembly is a power supply line assembly that forms part of the aforementioned power supply path, connecting the aforementioned auxiliary power supply device to the aforementioned power supply object. The aforementioned auxiliary power supply device includes: An auxiliary power supply, located in the aforementioned power supply path, is used to assist in the power supply from the aforementioned external power source to the aforementioned power-supplying object; and The switching circuit is configured to switch the connection state of the auxiliary power supply relative to the power supply path. The aforementioned auxiliary power supply connection state includes a boost state in which the auxiliary power supply is connected in series with the external power supply and the object being powered. The aforementioned power supply line group includes multiple discrete power supply lines connected to the aforementioned multiple power supply systems. The upstream ends of each of the aforementioned discrete power supply lines are connected to the aforementioned power supply path closer to the downstream side than the aforementioned auxiliary power supply. The aforementioned auxiliary power supply device also includes a boost circuit, which is arranged in the power supply path such that, in the boosted state, it is located closer to the downstream side than the auxiliary power supply. The upstream ends of each of the aforementioned discrete power supply lines are connected to the aforementioned power supply path closer to the downstream side than the aforementioned boost circuit. The aforementioned power supply path, between the aforementioned boost circuit and the aforementioned upstream end, only has wiring for transmitting power.

2. The auxiliary power supply unit according to claim 1, wherein, The connection state of the aforementioned auxiliary power supply also includes a charging state, in which the auxiliary power supply is connected in parallel with the power supply object for the aforementioned external power supply.

3. The auxiliary power supply unit according to claim 1 or 2, wherein, The connection state of the auxiliary power supply also includes a standby state, in which the auxiliary power supply is disconnected from the external power supply and connected to the power supply object.

4. The auxiliary power supply unit according to claim 1 or 2, wherein, The aforementioned auxiliary power supply device also includes a switching control circuit, which is configured to control the aforementioned switching circuit. When the external power supply is normal and a large amount of power is supplied to the power source, the switching control circuit controls the switching circuit so that the connection state of the auxiliary power supply becomes the boost state.

5. The auxiliary power supply unit according to claim 4, wherein, The aforementioned power supply is for the motor unit, which serves as the drive source for the vehicle's steering control system. The above condition is the first condition, which includes: The vehicle speed is below the driving determination threshold; and The steering wheel speed is above the steering operation execution threshold.

6. The auxiliary power supply unit according to claim 4, wherein, The aforementioned power supply is for the motor unit, which serves as the drive source for the vehicle's steering control system. The above condition is the second condition, which includes the steering speed of the steering wheel being above the high-speed steering judgment threshold.

7. A steering control device, comprising: The motor unit has multiple power supply systems; and The auxiliary power supply unit according to claim 1 or 2 supplies power from an external power source to the motor unit.

8. An auxiliary power supply unit, which supplies power from an external power source to a power supply object having multiple power supply systems, comprising: An auxiliary power supply device is disposed midway in the power supply path from the external power source to the object being powered; and The power supply line assembly is a power supply line assembly that forms part of the aforementioned power supply path, connecting the aforementioned auxiliary power supply device to the aforementioned power supply object. The aforementioned auxiliary power supply device includes: An auxiliary power supply, located in the aforementioned power supply path, is used to assist in the power supply from the aforementioned external power source to the aforementioned power-supplying object; and The switching circuit is configured to switch the connection state of the auxiliary power supply relative to the power supply path. The aforementioned auxiliary power supply connection state includes a boost state in which the auxiliary power supply is connected in series with the external power supply and the object being powered. The aforementioned power supply line group includes multiple discrete power supply lines connected to the aforementioned multiple power supply systems. The upstream ends of each of the aforementioned discrete power supply lines are connected to the aforementioned power supply path closer to the downstream side than the aforementioned auxiliary power supply. The aforementioned external power supply includes a first power supply and a second power supply. The aforementioned power supply path includes a first power supply path and a second power supply path, wherein, The first power supply path supplies power from the first power source to the power supply object, and the second power supply path supplies power from the second power source to the power supply object. The aforementioned power supply line group includes: The first power supply line group, which forms part of the aforementioned first power supply path, connects the aforementioned auxiliary power supply device to the aforementioned power supply object; and The second power supply line group, which forms part of the second power supply path, connects the auxiliary power supply device to the object being powered. The aforementioned auxiliary power supply includes: A first auxiliary power supply is provided in the first power supply path to assist in the power supply from the first power source to the power supply object; and A second auxiliary power source is provided in the second power supply path to assist in the power supply from the second power source to the power supply object. The switching circuit mentioned above includes: The first switching circuit is configured to switch the connection state of the first auxiliary power supply relative to the first power supply path; and The second switching circuit is configured to switch the connection state of the second auxiliary power supply relative to the second power supply path. The aforementioned first power supply line group includes multiple first discrete power supply lines. The aforementioned second power supply line group includes multiple second discrete power supply lines. The upstream ends of each of the aforementioned plurality of first discrete power supply lines are connected to the aforementioned first power supply path closer to the downstream side than the aforementioned first auxiliary power supply. The upstream ends of each of the aforementioned plurality of second discrete power supply lines are connected to the aforementioned second power supply path closer to the downstream side than the aforementioned second auxiliary power supply. The aforementioned auxiliary power supply device also includes: The first boost circuit is provided in the first power supply path such that, in the boost state, it is located closer to the downstream side than the first auxiliary power supply. The second boost circuit is provided in the second power supply path in such a way that, in the boost state, it is located closer to the downstream side than the second auxiliary power supply. as well as The boost control circuit is configured to control the first boost circuit and the second boost circuit so that the output voltage from the first boost circuit is equal to the output voltage from the second boost circuit. The upstream ends of each of the aforementioned plurality of first discrete power supply lines are connected to the aforementioned first power supply path closer to the downstream side than the aforementioned first boost circuit. The upstream ends of each of the aforementioned plurality of second discrete power supply lines are connected to the aforementioned second power supply path closer to the downstream side than the aforementioned second boost circuit.

9. The auxiliary power supply unit according to claim 8, wherein, The connection state of the aforementioned auxiliary power supply also includes a charging state, in which the auxiliary power supply is connected in parallel with the power supply object for the aforementioned external power supply.

10. The auxiliary power supply unit according to claim 8 or 9, wherein, The connection state of the auxiliary power supply also includes a standby state, in which the auxiliary power supply is disconnected from the external power supply and connected to the power supply object.

11. The auxiliary power supply unit according to claim 8 or 9, wherein, The aforementioned auxiliary power supply device also includes a switching control circuit, which is configured to control the aforementioned switching circuit. When the external power supply is normal and a large amount of power is supplied to the power source, the switching control circuit controls the switching circuit so that the connection state of the auxiliary power supply becomes the boost state.

12. The auxiliary power supply unit according to claim 11, wherein, The aforementioned power supply is for the motor unit, which serves as the drive source for the vehicle's steering control system. The above condition is the first condition, which includes: The vehicle speed is below the driving determination threshold; and The steering wheel speed is above the steering operation execution threshold.

13. The auxiliary power supply unit according to claim 11, wherein, The aforementioned power supply is for the motor unit, which serves as the drive source for the vehicle's steering control system. The above condition is the second condition, which includes the steering speed of the steering wheel being above the high-speed steering judgment threshold.

14. A steering control device, comprising: The motor unit has multiple power supply systems; and The auxiliary power supply unit according to claim 8 or 9 supplies power from an external power source to the motor unit.

15. A control method for an auxiliary power supply unit, which is a control method for supplying power from an external power source to an auxiliary power supply unit that has multiple power supply systems. The aforementioned auxiliary power supply unit includes: An auxiliary power supply device is disposed midway in the power supply path from the external power source to the object being powered; and The power supply line assembly is a power supply line assembly that forms part of the aforementioned power supply path, connecting the aforementioned auxiliary power supply device to the aforementioned power supply object. The aforementioned auxiliary power supply device includes: An auxiliary power supply, located in the aforementioned power supply path, is used to assist in the power supply from the aforementioned external power source to the aforementioned power-supplying object; and The switching circuit is configured to switch the connection state of the auxiliary power supply relative to the power supply path. The aforementioned auxiliary power supply connection state includes a boost state in which the auxiliary power supply is connected in series with the external power supply and the object being powered. The aforementioned power supply line group includes multiple discrete power supply lines connected to the aforementioned multiple power supply systems. The upstream ends of each of the aforementioned discrete power supply lines are connected to the aforementioned power supply path closer to the downstream side than the aforementioned auxiliary power supply. The aforementioned auxiliary power supply device also includes a boost circuit, which is arranged in the power supply path such that, in the boosted state, it is located closer to the downstream side than the auxiliary power supply. The upstream ends of each of the aforementioned discrete power supply lines are connected to the aforementioned power supply path closer to the downstream side than the aforementioned boost circuit. The aforementioned power supply path, between the aforementioned boost circuit and the aforementioned upstream end, only has wiring for transmitting power. The above control methods include: Determine if the external power supply is functioning correctly. Determine whether the conditions for supplying a large amount of electricity to the aforementioned power source are met; and When the voltage of the external power supply is normal and the above conditions are met, the switching circuit is controlled so that the connection state of the auxiliary power supply becomes the boost state.

16. A control method for an auxiliary power supply unit, which is a control method for supplying power from an external power source to an auxiliary power supply unit that has multiple power supply systems. The aforementioned auxiliary power supply unit includes: An auxiliary power supply device is disposed midway in the power supply path from the external power source to the object being powered; and The power supply line assembly is a power supply line assembly that forms part of the aforementioned power supply path, connecting the aforementioned auxiliary power supply device to the aforementioned power supply object. The aforementioned auxiliary power supply device includes: An auxiliary power supply, located in the aforementioned power supply path, is used to assist in the power supply from the aforementioned external power source to the aforementioned power-supplying object; and The switching circuit is configured to switch the connection state of the auxiliary power supply relative to the power supply path. The aforementioned auxiliary power supply connection state includes a boost state in which the auxiliary power supply is connected in series with the external power supply and the object being powered. The aforementioned power supply line group includes multiple discrete power supply lines connected to the aforementioned multiple power supply systems. The upstream ends of each of the aforementioned discrete power supply lines are connected to the aforementioned power supply path closer to the downstream side than the aforementioned auxiliary power supply. The aforementioned external power supply includes a first power supply and a second power supply. The aforementioned power supply path includes a first power supply path and a second power supply path, wherein, The first power supply path supplies power from the first power source to the power supply object, and the second power supply path supplies power from the second power source to the power supply object. The aforementioned power supply line group includes: The first power supply line group, which forms part of the aforementioned first power supply path, connects the aforementioned auxiliary power supply device to the aforementioned power supply object; and The second power supply line group, which forms part of the second power supply path, connects the auxiliary power supply device to the object being powered. The aforementioned auxiliary power supply includes: A first auxiliary power supply is provided in the first power supply path to assist in the power supply from the first power source to the power supply object; and A second auxiliary power source is provided in the second power supply path to assist in the power supply from the second power source to the power supply object. The switching circuit mentioned above includes: The first switching circuit is configured to switch the connection state of the first auxiliary power supply relative to the first power supply path; and The second switching circuit is configured to switch the connection state of the second auxiliary power supply relative to the second power supply path. The aforementioned first power supply line group includes multiple first discrete power supply lines. The aforementioned second power supply line group includes multiple second discrete power supply lines. The upstream ends of each of the aforementioned plurality of first discrete power supply lines are connected to the aforementioned first power supply path closer to the downstream side than the aforementioned first auxiliary power supply. The upstream ends of each of the aforementioned plurality of second discrete power supply lines are connected to the aforementioned second power supply path closer to the downstream side than the aforementioned second auxiliary power supply. The aforementioned auxiliary power supply device also includes: The first boost circuit is provided in the first power supply path such that, in the boost state, it is located closer to the downstream side than the first auxiliary power supply. The second boost circuit is provided in the second power supply path in such a way that, in the boost state, it is located closer to the downstream side than the second auxiliary power supply. as well as The boost control circuit is configured to control the first boost circuit and the second boost circuit so that the output voltage from the first boost circuit is equal to the output voltage from the second boost circuit. The upstream ends of each of the aforementioned plurality of first discrete power supply lines are connected to the aforementioned first power supply path closer to the downstream side than the aforementioned first boost circuit. The upstream ends of each of the aforementioned plurality of second discrete power supply lines are connected to the aforementioned second power supply path closer to the downstream side than the aforementioned second boost circuit. The above control methods include: Determine if the external power supply is functioning correctly. Determine whether the conditions for supplying a large amount of electricity to the aforementioned power source are met; and When the voltage of the external power supply is normal and the above conditions are met, the switching circuit is controlled so that the connection state of the auxiliary power supply becomes the boost state.

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