Control device, vehicle, control method, and recording medium having control program recorded

Abstract

The present application relates to a control device, a vehicle, a control method, and a recording medium on which a control program is recorded. The control device controls a first DCDC converter and a second DCDC converter that supply electric power to an apparatus, and includes a control section that performs feedback control in such a manner that the output of the first DCDC converter is fixed to a maximum value when the output of the first DCDC converter is at a maximum value, and the output of the second DCDC converter satisfies a prescribed condition.

Description

Technical Field

[0001] This disclosure relates to control devices, vehicles, control methods, and recording media containing control programs. Background Technology

[0002] Japanese Patent No. 5387651 discloses a power supply system for coordinated control of multiple DC-DC converters.

[0003] In power supply systems, by assigning a high voltage indication value to one DC-DC converter and a low voltage indication value to the other, it is possible to prioritize the use of that DC-DC converter. However, in this case, if the load on the device increases, there is a concern that the voltage of that device may be fixed at the low voltage indication value of the DC-DC converter side. Summary of the Invention

[0004] The purpose of this disclosure is to provide a control device, vehicle, control method, and recording medium containing a control program that can supply a requested voltage to a device regardless of the device's load when power is supplied to the device via multiple DC-DC converters.

[0005] The first method is a control device that controls a first DC-DC converter and a second DC-DC converter that supply power to a device, wherein the device includes a control unit that performs feedback control by fixing the output of the first DC-DC converter to its maximum when the output of the first DC-DC converter is at its maximum, and by ensuring that the output of the second DC-DC converter meets a predetermined condition.

[0006] The first method involves a control device that controls a first DC-DC converter and a second DC-DC converter. The first and second DC-DC converters are configured to supply power to the same device. In this control device, for example, when the output of the first DC-DC converter, which supplies power to the device before the second DC-DC converter, is at its maximum, the control unit performs feedback control such that the output of the second DC-DC converter meets predetermined conditions. These predetermined conditions could include the device's voltage reaching a desired target value, or the reference voltage of the battery supplying power to the device reaching a target value. According to this control device, when the output of the first DC-DC converter is at its maximum, regardless of the device's load, the requested voltage can be supplied to the device through feedback control based on the second DC-DC converter.

[0007] The control device of the second method is based on the control device of the first method. When the voltage indication value of the first DC-DC converter is less than the maximum value, the control unit performs feedback control in such a way that the voltage indication value of the first DC-DC converter becomes the target value, and controls the voltage indication value of the second DC-DC converter to be a value lower than the voltage indication value of the first DC-DC converter by a predetermined value. When the voltage indication value of the first DC-DC converter reaches the maximum value, the control unit performs control in such a way that the voltage indication value of the first DC-DC converter becomes the maximum value, and performs feedback control in such a way that the voltage indication value of the second DC-DC converter becomes the target value.

[0008] In the control device of the second method, when the output of the first DC-DC converter has a sufficient normal voltage, feedback control is performed to make the power indication value of the first DC-DC converter the target value, and control is performed to make the power indication value of the second DC-DC converter a value lower than the power indication value of the first DC-DC converter, thereby maintaining the voltage to the device. On the other hand, when the output of the first DC-DC converter reaches its maximum overload, feedback control is performed to maximize the power indication value of the first DC-DC converter and make the power indication value of the second DC-DC converter the target value. Therefore, according to this control device, the requested voltage is supplied to the device under normal conditions regardless of the load, and when the load begins to increase and becomes overloaded, the voltage of the device can be quickly made to the target value by means of the second DC-DC converter.

[0009] The control device of the third method is based on the control device of the first method. When the voltage indication value of the first DC-DC converter is less than the maximum value, the control unit performs feedback control in such a way that the voltage indication value of the first DC-DC converter becomes the target value, and performs feedback control in such a way that the voltage indication value of the second DC-DC converter becomes a value lower than the target value by a predetermined value. When the voltage indication value of the first DC-DC converter reaches the maximum value, the control unit performs control in such a way that the voltage indication value of the first DC-DC converter becomes the maximum value, and performs feedback control in such a way that the voltage indication value of the second DC-DC converter becomes the target value.

[0010] In the control device of the third method, when the output of the first DC-DC converter has a sufficient normal voltage, feedback control is performed by setting the power indication value of the first DC-DC converter to a target value, and feedback control is performed by setting the power indication value of the second DC-DC converter to a value lower than the target value by a predetermined value, to maintain the voltage to the device. On the other hand, when the output of the first DC-DC converter reaches its maximum overload, the power indication value of the first DC-DC converter is maximized, and feedback control is performed by setting the power indication value of the second DC-DC converter to a target value. Therefore, according to this control device, the requested voltage can be supplied to the device under normal conditions regardless of the load, and when the load begins to increase, the voltage can be rapidly increased by the second DC-DC converter to keep up with the increase in load.

[0011] The control device of the fourth method is based on the control device of the second method. When the voltage indication value of the first DC-DC converter is less than the maximum value and a specific load is generated in the device, the control unit performs feedback control in such a way that the voltage indication value of the first DC-DC converter becomes the target value, and performs feedback control in such a way that the voltage indication value of the second DC-DC converter becomes a value that is lower than the target value by a predetermined value.

[0012] The fourth type of control device is characterized by a control method for a second DC-DC converter when the output of the first DC-DC converter has a margin of safety. In this control device, the voltage to the device is maintained by controlling the second DC-DC converter so that its power indication value is lower than the power indication value of the first DC-DC converter by a predetermined value. However, when a specific load is generated in the device, the voltage to the device is maintained by feedback control where the power indication value of the second DC-DC converter is lower than a target value by a predetermined value. According to this control device, the voltage following characteristics of the device can be changed according to the type of load.

[0013] The control device of the fifth method is based on the control device of any of the methods 2 to 4, and the above-mentioned specified value is set to take into account the deviation of the output of the DC-DC converter.

[0014] If the specified value is increased excessively, the voltage supported by the output of the second DC-DC converter will decrease due to increased equipment load and insufficient output from the first DC-DC converter. Conversely, if the specified value is decreased excessively, the quality of the output will be compromised based on the deviation between the outputs of the two DC-DC converters, making it impossible to achieve priority output from the first DC-DC converter. In contrast, the control device according to the fifth method can ensure priority output from the first DC-DC converter and ensure the supplementary output from the second DC-DC converter.

[0015] The vehicle of the sixth type includes: a control device of any one of the first to fifth types; a high-voltage battery that supplies power to the first DC-DC converter and the second DC-DC converter respectively; and an auxiliary battery that supplies power to the device and receives power from the first DC-DC converter and the second DC-DC converter respectively.

[0016] According to the vehicle of the sixth method, when the output of the first DC-DC converter becomes maximum, the requested voltage can be supplied to the device through feedback control based on the second DC-DC converter, regardless of the device load, and the auxiliary battery can be kept in the prescribed state of charge.

[0017] The seventh control method is a control method for the first DC-DC converter and the second DC-DC converter that supply power to the equipment. The computer performs the following processing: when the output of the first DC-DC converter is at its maximum, the output of the first DC-DC converter is fixed at its maximum, and feedback control is performed in a manner that the output of the second DC-DC converter meets the specified conditions.

[0018] The seventh control method is a method for controlling the first DC-DC converter and the second DC-DC converter. As described above, the first and second DC-DC converters are configured to supply power to the same device. In this control method, for example, when the output of the first DC-DC converter, which supplies power to the device before the second DC-DC converter, is at its maximum, the computer performs feedback control such that the output of the second DC-DC converter meets a predetermined condition. Here, the predetermined condition is the same as described above. According to this control method, when the output of the first DC-DC converter is at its maximum, the requested voltage can be supplied to the device through feedback control based on the second DC-DC converter, regardless of the device's load.

[0019] The eighth method is a non-temporary recording medium containing a control program. This control program controls the first and second DC-DC converters supplying power to the device. The control program causes the computer to perform the following processing: when the output of the first DC-DC converter is at its maximum, fix the output of the first DC-DC converter at its maximum, and perform feedback control in a manner that ensures the output of the second DC-DC converter meets predetermined conditions.

[0020] The control program recorded on the non-transitory recording medium of the eighth method causes the computer to control the first DC-DC converter and the second DC-DC converter. As described above, the first and second DC-DC converters are configured to supply power to the same device. In this program, for example, when the output of the first DC-DC converter, which supplies power to the device before the second DC-DC converter, is at its maximum, the computer performs feedback control such that the output of the second DC-DC converter meets a predetermined condition. Here, the predetermined condition is the same as described above. According to this program, when the output of the first DC-DC converter is at its maximum, the requested voltage can be supplied to the device through feedback control based on the second DC-DC converter, regardless of the device's load.

[0021] According to this disclosure, when power is supplied to a device via multiple DC-DC converters, the requested voltage can be supplied to the device regardless of the device's load. Attached Figure Description

[0022] An exemplary embodiment of the present invention will be described in detail based on the following figures, wherein:

[0023] Figure 1 This is a simplified structural diagram of the vehicle and power supply system involved in the first embodiment.

[0024] Figure 2 This is a block diagram showing the structure of the ROM in the ECU of the first embodiment.

[0025] Figure 3 This is a block diagram showing the functional structure of the CPU in the ECU of the first embodiment.

[0026] Figure 4 This is a diagram illustrating the relationship between the voltage indication value of the first DC-DC converter and the voltage indication value of the second DC-DC converter in the first embodiment.

[0027] Figure 5 This is a flowchart illustrating the power control process in the first embodiment.

[0028] Figure 6 This is a graph showing the voltage indication values ​​of each DC-DC converter and the voltage values ​​of the auxiliary equipment in the power supply system of the first embodiment as the load of auxiliary equipment increases.

[0029] Figure 7 This is a flowchart illustrating the power control process in the second embodiment.

[0030] Figure 8This is a graph showing the voltage indication values ​​of each DC-DC converter and the voltage values ​​of the auxiliary equipment in the power supply system of the second embodiment as the load of the auxiliary equipment increases.

[0031] Figure 9 This is a flowchart illustrating the power control process in the third embodiment.

[0032] Figure 10 This is a diagram illustrating the method for setting the voltage indication value of the second DC-DC converter in Modification 1. Detailed Implementation

[0033] Hereinafter, an example of an embodiment of the present disclosure will be described in detail with reference to the accompanying drawings.

[0034] [First Implementation]

[0035] (structure)

[0036] like Figure 1 As shown, the power supply system 10 of the first embodiment is mounted on a vehicle 12. The vehicle 12 may be exemplified as an EV (Electric Vehicle) or an HV (Hybrid Vehicle). The vehicle 12 of this embodiment is supplied with power by the power supply system 10. The vehicle 12 includes auxiliary equipment 32 as devices that operate various parts of the vehicle 12, and an ECU group 34 that controls various parts of the vehicle 12 including the auxiliary equipment 32.

[0037] The power supply system 10 is configured to include an ECU 20 as a control device, a high-voltage battery 22, a DC-DC converter 24, and an auxiliary battery 28. Details regarding the ECU 20 will be described later. Furthermore, the DC-DC converter 24 in this embodiment includes a first DC-DC converter 25 and a second DC-DC converter 26.

[0038] The high-voltage battery 22 is a high-voltage battery used to operate the drive motor and other components related to the drive of the vehicle 12. It is composed of, for example, a rechargeable secondary battery such as a lithium battery or a nickel-metal hydride battery. The high-voltage battery 22 is connected to the first DC-DC converter 25 and the second DC-DC converter 26.

[0039] The first DC-DC converter 25 has the function of supplying power from the high-voltage battery 22 to the auxiliary battery 28 and the auxiliary equipment 32. The first DC-DC converter 25 is connected to the high-voltage battery 22 on the input side and to the auxiliary battery 28 and the auxiliary equipment 32 on the output side. When power is supplied, the first DC-DC converter 25 steps down the output voltage of the high-voltage battery 22 (which is the input voltage) to a predetermined voltage based on an instruction from the ECU 20 and outputs it to the auxiliary battery 28 and the auxiliary equipment 32.

[0040] The second DC-DC converter 26 has the same function as the first DC-DC converter 25. That is, the second DC-DC converter 26 has the function of supplying power output from the high-voltage battery 22 to the auxiliary battery 28 and the auxiliary equipment 32. The second DC-DC converter 26 is connected to the high-voltage battery 22 on the input side and to the auxiliary battery 28 and the auxiliary equipment 32 on the output side. When power is supplied, the second DC-DC converter 26 steps down the output voltage of the high-voltage battery 22, which is the input voltage, to a specified voltage based on the instruction from the ECU 20 and outputs it to the auxiliary battery 28 and the auxiliary equipment 32.

[0041] In the power supply system 10 of this embodiment, the ECU 20 described later controls the first DC-DC converter 25 to supply power to the auxiliary equipment 32 in a way that prioritizes the second DC-DC converter 26.

[0042] The auxiliary battery 28 is a battery that enables the operation of the auxiliary equipment 32, and is composed of a rechargeable secondary battery such as a lead-acid battery or a lithium-ion battery. The auxiliary battery 28 is connected to both the first DC-DC converter 25 and the second DC-DC converter 26, and can receive power from each of them. Furthermore, the auxiliary battery 28 is connected to the auxiliary equipment 32 of the vehicle 12, supplying power to the auxiliary equipment 32.

[0043] ECU 20, for example, is composed of a microcomputer and has the function of controlling the first DC-DC converter 25 and the second DC-DC converter 26. Thus, ECU 20 supplies power from the high-voltage battery 22 to the auxiliary battery 28 and the auxiliary equipment 32 via the first DC-DC converter 25 and the second DC-DC converter 26.

[0044] ECU20 is configured to include a CPU (Central Processing Unit) 20A, a ROM (Read Only Memory) 20B, a RAM (Random Access Memory) 20C, an I / O interface (I / F) 20D, and a communication interface (I / F) 20E. The CPU 20A, ROM 20B, RAM 20C, I / O interface (I / F) 20D, and communication interface (I / F) 20E are connected via an internal bus 20F and are capable of communicating with each other. The CPU 20A is an example of a processor, and the RAM 20C is an example of a memory.

[0045] CPU20A is the central processing unit, which executes various programs and controls other components. Specifically, CPU20A reads programs from ROM20B and uses RAM20C as its working area to execute the programs.

[0046] The ROM20B, as part of the storage unit, stores various programs and data. For example... Figure 2 As shown, in this embodiment, ROM20B stores control program 100 and setting data 110.

[0047] Control program 100 is a program used to control ECU 20. ECU 20, controlled by the control program, controls the first DC-DC converter 25 and the second DC-DC converter 26.

[0048] The setting data 110 stores the control parameters used for feedback control in each DC-DC converter.

[0049] like Figure 1 As shown, RAM20C is used as a working area to temporarily store programs or data.

[0050] The input / output I / F20D is an interface used for communication with the first DC-DC converter 25 and the second DC-DC converter 26, respectively.

[0051] Communication I / F20E is an interface used to connect to ECU group 34. This interface can use, for example, a communication standard based on the CAN protocol. Communication I / F20E is connected to external bus 20H. Thus, ECU 20 can obtain the operating status of various parts of vehicle 12 via Communication I / F20E.

[0052] Furthermore, the ECU20 may include a storage unit in addition to the ROM20B, or may include a storage unit instead of the ROM20B. This storage unit may be, for example, an HDD (Hard Disk Drive) or an SSD (Solid State Drive).

[0053] like Figure 3 As shown, in the ECU20 of this embodiment, the CPU20A executes the control program 100 to function as the acquisition unit 200 and the control unit 220.

[0054] The acquisition unit 200 has the function of acquiring the status of the first DC-DC converter 25 and the second DC-DC converter 26. Here, the status acquired from each DC-DC converter 24 includes the output voltage of each DC-DC converter 24. In addition, the acquisition unit 200 acquires the voltage of the auxiliary battery 28. Furthermore, the acquisition unit 200 can acquire the operating status of each part, including the auxiliary equipment type 32 in the vehicle 12, from the ECU group 34.

[0055] The control unit 220 performs power control processing to control the output of each DC-DC converter 24. In this embodiment, the control unit 220 adjusts the output power by setting a voltage indication value for each DC-DC converter 24. Normally, the control unit 220 controls the output of the first DC-DC converter 25 by setting a voltage indication value V that is lower than that of the second DC-DC converter 26.

[0056] Here, if the value of V is increased excessively, the voltage supported by the output of the second DC-DC converter 26 will decrease when the load on the auxiliary unit 32 increases and the output of the first DC-DC converter 25 is insufficient. Conversely, if the value of V is decreased excessively, the quality of the output will be compromised due to the deviation between the outputs of the two DC-DC converters 24, making it impossible to achieve the initially intended priority output of the first DC-DC converter 25. Therefore, in this embodiment, a predetermined value V is set as follows.

[0057] like Figure 4 As shown, the power indication value of the first DC-DC converter 25 is set to V1, and the voltage deviation accompanying the output deviation is set to ±d1. The power indication value of the second DC-DC converter 26 is set to V2, and the voltage deviation accompanying the output deviation is set to ±d2. Furthermore, the minimum voltage difference that should be ensured between the first DC-DC converter 25 and the second DC-DC converter 26 is set to D1. Therefore, V2 = V1 - (d1 + d2 + D1). That is, it is sufficient to set it to the specified value V = d1 + d2 + D1.

[0058] (Control process)

[0059] use Figure 5 The flowchart illustrates the power control processing performed in the ECU 20 of this embodiment. The processing in the ECU 20 is implemented by the CPU 20A, which functions as the aforementioned acquisition unit 200 and control unit 220. In the figures, "DC-CDC converter" is abbreviated as "DDC," and "feedback control" is abbreviated as "FB control."

[0060] The power control processing of the control method in this embodiment controls the output by setting the voltage indication value of each DC-DC converter 24.

[0061] exist Figure 5 In step S100, CPU20A sets the power indication value of the first DC-DC converter 25 to an initial value and sets the power indication value of the second DC-DC converter 26 to an initial value.

[0062] In step S101, CPU 20A determines whether the voltage indication value of the first DC-DC converter 25 is greater than or equal to the maximum value. If it is determined that the voltage indication value of the first DC-DC converter 25 is greater than or equal to the maximum value (if "yes" is true in step S101), CPU 20A proceeds to step S103. On the other hand, if it is determined that the voltage indication value of the first DC-DC converter 25 is not greater than or equal to the maximum value, i.e., less than the maximum value (if "no" is true in step S101), CPU 20A proceeds to step S102.

[0063] In step S102, CPU 20A sets the voltage indication value of the first DC-DC converter 25 using feedback control based on the target value of the auxiliary battery 28, and sets the voltage indication value of the second DC-DC converter 26 to the value of the voltage indication value of the first DC-DC converter 25 minus V. Then, it returns to step S100.

[0064] In step S103, the CPU 20A determines whether the voltage indication value of the second DC-DC converter 26 is less than the voltage indication value -V of the first DC-DC converter 25. If it is determined that the voltage indication value of the second DC-DC converter 26 is less than the voltage indication value -V of the first DC-DC converter 25 (if "Yes" is true in step S103), the CPU 20A proceeds to step S102. On the other hand, if it is determined that the voltage indication value of the second DC-DC converter 26 is not less than the voltage indication value -V of the first DC-DC converter 25, that is, it is greater than or equal to the voltage indication value -V of the first DC-DC converter 25 (if "No" is true in step S103), the CPU 20A proceeds to step S104.

[0065] In step S104, CPU 20A sets the voltage indication value of the first DC-DC converter 25 to its maximum value, and sets the voltage indication value of the second DC-DC converter 26 in a feedback control manner using the target value of the auxiliary battery 28 voltage. Then, it returns to step S100.

[0066] If reference Figure 6 The following example illustrates the role of the power control processing involved in the above flowchart. When the output of the first DC-DC converter 25 has a sufficient normal voltage, the voltage Vb1 of the auxiliary unit 32 is maintained by using the target value of the voltage of the auxiliary battery 28 to perform feedback control on the power indication value V1 of the first DC-DC converter 25 (see step S102).

[0067] Here, if the load of auxiliary unit 32 increases at time X, the voltage Vb1 of auxiliary battery 28 drops sharply. Simultaneously, CPU 20A increases the voltage indication value V1 of the first DC-DC converter 25 and, in a coordinated manner, increases the power indication value V2 of the second DC-DC converter 26 to increase the voltage Vb1 of auxiliary battery 28.

[0068] Then, if at time Y the output of the first DC-DC converter 25 reaches the maximum overload, the power indication value V1 of the first DC-DC converter 25 is set to the maximum, and the power indication value V2 of the second DC-DC converter 26 is controlled by feedback using the target value of the voltage of the auxiliary battery 28, thereby maintaining the voltage Vb1 of the auxiliary unit 32 (see step S104).

[0069] exist Figure 6 In the example, while maintaining the voltage indication value V1 of the first DC-DC converter 25 at its maximum value, the CPU 20A feeds back the power indication value V2 of the second DC-DC converter 26 by restoring the voltage Vb1 of the auxiliary battery 28 to its initial value. Therefore, as the voltage Vb1 recovers and stabilizes, the increase in the power indication value V2 also weakens.

[0070] Furthermore, if the load on auxiliary unit 32 subsequently decreases, the voltage Vb1 of auxiliary unit 32 will approach the voltage indication value V1 (i.e., the maximum value) of the first DC-DC converter 25. As a result, the power indication value V2 of the second DC-DC converter 26, which is performing feedback control, decreases, returning to normal control (see step S103).

[0071] (Summary of Implementation Methods)

[0072] In the power supply system 10 of this embodiment, the ECU 20 is configured to control a first DC-DC converter 25 and a second DC-DC converter 26 to supply power to the auxiliary equipment 32. In the ECU 20 of this embodiment, regardless of the load on the auxiliary equipment 32, the requested voltage can be supplied to the auxiliary equipment 32 through the aforementioned power control processing. Specifically, when the output of the first DC-DC converter 25 has sufficient normal capacity, the requested voltage is supplied to the auxiliary equipment 32 regardless of its load. When the load begins to increase and becomes overloaded, the voltage of the auxiliary equipment 32 can be quickly restored by the second DC-DC converter 26.

[0073] Furthermore, as in the vehicle 12 of this embodiment, since the required voltage can be supplied to the auxiliary equipment 32 regardless of the load on the auxiliary equipment 32, the auxiliary battery 28 can be kept in a predetermined charging state.

[0074] [Second Implementation]

[0075] The second embodiment differs from the first embodiment in that the method for setting the voltage indication value of the second DC-DC converter 26 is generally different. The structure of the power supply system 10 in this embodiment is the same as that in the first embodiment; the same reference numerals denote the same structure, and detailed descriptions are omitted.

[0076] The following uses Figure 7 The power control process of this embodiment will be described. Steps identical to those in the power control process of the first embodiment will be labeled with the same step number and their descriptions omitted.

[0077] exist Figure 7 In step S101, if it is determined that the voltage indication value of the first DC-DC converter 25 is less than the maximum value (if "No" is true in step S101), the CPU 20A performs the following processing in step S200. Additionally, in step S103, if it is determined that the voltage indication value of the second DC-DC converter 26 is less than the value that becomes the voltage indication value -V of the first DC-DC converter 25 (if "Yes" is true in step S103), the CPU 20A also performs the processing of step S200.

[0078] In step S200, CPU 20A sets the voltage indication value of the first DC-DC converter 25 using feedback control based on a target value of the auxiliary battery 28's voltage, and sets the voltage indication value of the second DC-DC converter 26 using feedback control based on a value that is the target value of the auxiliary battery 28's voltage – V. Here, V is set as a predetermined value based on the same idea as in the first embodiment. Then, the process returns to step S100.

[0079] If reference Figure 8 The following example illustrates the operation of the power control process in this embodiment. When the output of the first DC-DC converter 25 has a sufficient normal voltage, the voltage Vb2 of the auxiliary unit 32 is maintained by feedback control of the power indication value V1 of the first DC-DC converter 25 using the target value of the voltage of the auxiliary battery 28 (see step S200).

[0080] Here, if the load of auxiliary unit 32 increases at time X, the voltage Vb2 of auxiliary battery 28 drops sharply. Simultaneously, CPU 20A increases the voltage indication value V1 of the first DC-DC converter 25. Furthermore, with the feedback control in step S200, the power indication value V2 of the second DC-DC converter 26 increases sharply, and the voltage Vb2 of auxiliary battery 28 increases sharply in response.

[0081] Then, if at time Y the output of the first DC-DC converter 25 reaches the maximum overload, the voltage Vb2 of the auxiliary equipment 32 is maintained by making the power indication value V1 of the first DC-DC converter 25 the maximum and using the target value of the voltage of the auxiliary battery 28 to perform feedback control on the power indication value V2 of the second DC-DC converter 26 (see step S104).

[0082] exist Figure 8 In the example, if the voltage indication value V1 of the first DC-DC converter 25 is maintained at its maximum value, then with feedback control, the power indication value V2 of the second DC-DC converter 26 increases sharply again, and the voltage Vb2 of the auxiliary battery 28 increases sharply in response. Then, as the voltage Vb2 recovers and the voltage value stabilizes, the increase in the power indication value V2 also weakens.

[0083] As described above, according to this embodiment, when the output of the first DC-DC converter 25 has sufficient normal voltage, the required voltage is supplied to the auxiliary device 32 regardless of its load. Furthermore, when the load begins to increase, the voltage can be rapidly increased by the second DC-DC converter 26 in line with the increase in load.

[0084] [Third Implementation]

[0085] In the third embodiment, a power control process combining the first and second embodiments is performed. The structure of the power supply system 10 in this embodiment is the same as that in the first embodiment; the same reference numerals denote the same structures, and detailed descriptions are omitted.

[0086] The following uses Figure 9 The power control processing of this embodiment will be explained.

[0087] exist Figure 9 In step S300, CPU20A sets the power indication value of the first DC-DC converter 25 to an initial value and sets the power indication value of the second DC-DC converter 26 to an initial value.

[0088] In step S301, CPU 20A determines whether a specific load is ON. Examples of specific loads in this embodiment include the operation of auxiliary equipment such as the headlights (of type 32) and electric power steering. If the specific load is determined to be ON (if "Yes" in step S301), CPU 20A proceeds to step S306. Conversely, if the specific load is determined to be OFF (if "No" in step S301), CPU 20A proceeds to step S302.

[0089] In step S302, CPU 20A determines whether the voltage indication value of the first DC-DC converter 25 is greater than or equal to the maximum value. If it is determined that the voltage indication value of the first DC-DC converter 25 is greater than or equal to the maximum value (if "yes" is true in step S302), CPU 20A proceeds to step S304. On the other hand, if it is determined that the voltage indication value of the first DC-DC converter 25 is not greater than or equal to the maximum value, i.e., less than the maximum value (if "no" is true in step S302), CPU 20A proceeds to step S303.

[0090] In step S303, CPU 20A sets the voltage indication value of the first DC-DC converter 25 using feedback control based on the target value of the auxiliary battery 28, and sets the voltage indication value of the second DC-DC converter 26 to the value of the voltage indication value of the first DC-DC converter 25 minus V. Then, it returns to step S300.

[0091] In step S304, the CPU 20A determines whether the voltage indication value of the second DC-DC converter 26 is less than the voltage indication value -V of the first DC-DC converter 25. If it is determined that the voltage indication value of the second DC-DC converter 26 is less than the voltage indication value -V of the first DC-DC converter 25 (if "Yes" is true in step S304), the CPU 20A proceeds to step S303. On the other hand, if it is determined that the voltage indication value of the second DC-DC converter 26 is not less than the voltage indication value -V of the first DC-DC converter 25, that is, is greater than or equal to the voltage indication value -V of the first DC-DC converter 25 (if "No" is true in step S304), the CPU 20A proceeds to step S305.

[0092] In step S305, CPU 20A sets the voltage indication value of the first DC-DC converter 25 to its maximum value, and sets the voltage indication value of the second DC-DC converter 26 using feedback control based on the target value of the auxiliary battery 28's voltage. Then, it returns to step S300.

[0093] In step S306, CPU 20A determines whether the voltage indication value of the first DC-DC converter 25 is greater than or equal to the maximum value. If it is determined that the voltage indication value of the first DC-DC converter 25 is greater than or equal to the maximum value (if "yes" is true in step S306), CPU 20A proceeds to step S308. On the other hand, if it is determined that the voltage indication value of the first DC-DC converter 25 is not greater than or equal to the maximum value, i.e., less than the maximum value (if "no" is true in step S306), CPU 20A proceeds to step S307.

[0094] In step S307, CPU 20A sets the voltage indication value of the first DC-DC converter 25 using feedback control based on the target value of the auxiliary battery 28's voltage, and sets the voltage indication value of the second DC-DC converter 26 using feedback control based on the target value of the auxiliary battery 28's voltage -V. Then, it returns to step S300.

[0095] In step S308, the CPU 20A determines whether the voltage indication value of the second DC-DC converter 26 is less than the voltage indication value -V of the first DC-DC converter 25. If it is determined that the voltage indication value of the second DC-DC converter 26 is less than the voltage indication value -V of the first DC-DC converter 25 (if "Yes" is true in step S308), the CPU 20A proceeds to step S307. On the other hand, if it is determined that the voltage indication value of the second DC-DC converter 26 is not less than the voltage indication value -V of the first DC-DC converter 25, that is, it is greater than or equal to the voltage indication value -V of the first DC-DC converter 25 (if "No" is true in step S308), the CPU 20A proceeds to step S305.

[0096] As described above, this embodiment is characterized by a control method for the second DC-DC converter 26 when the output of the first DC-DC converter 25 has a margin of safety. Specifically, in this embodiment, under conditions other than a specific load, the voltage to the auxiliary equipment 32 is maintained (control A) by controlling the second DC-DC converter 26 so that its power indication value is lower than the power indication value of the first DC-DC converter 25 by a predetermined value V.

[0097] On the other hand, when a specific load is generated, such as the headlights and electric power steering unit represented by auxiliary unit 32, the voltage of auxiliary unit 32 is maintained by feedback control (control B) when the power indication value of the second DC-DC converter 26 is lower than the target value of the voltage of the auxiliary battery 28 by a specified value V.

[0098] like Figure 8As shown, while control B (refer to Vb2) recovers from a momentary voltage drop earlier than control A (refer to Vb1), it takes longer to recover to the original voltage value before the load increase. Preferably, headlights and electric power steering units, exemplified as specific loads, are auxiliary equipment type 32 that affect the driving of vehicle 12, and the sudden voltage drop accompanying the load is suppressed as much as possible. Therefore, in this embodiment, control B is configured to be applied to specific loads that affect the driving of vehicle 12, and control A is applied to non-specific loads. According to this embodiment, the voltage following characteristics of auxiliary equipment type 32 can be changed according to the type of load.

[0099] (Modified Example)

[0100] In the above embodiment, when the output of the first DC-DC converter 25 has a sufficient normal voltage, the voltage indication value of the second DC-DC converter 26 is set to the value of the voltage indication value - V of the first DC-DC converter 25. For example, using... Figure 4 As explained, the specified value V is set to take into account the deviation of the output of each DC-DC converter 24. However, the method for setting the voltage indication value of the second DC-DC converter 26 in normal operation is not limited to this.

[0101] For example, in variation 1, such as Figure 10 As shown, the minimum voltage difference that should be ensured between the auxiliary battery 28 and the second DC-DC converter 26 is set to D2. Furthermore, the power indication value of the second DC-DC converter 26 is set to V2, and the voltage deviation accompanying the output deviation is set to ±d2. Thus, V2 = Vb - D2 - d2. That is, by setting the voltage indication value V2 of the second DC-DC converter 26 to Vb - D2 - d2, the first DC-DC converter 25 outputs power preferentially over the second DC-DC converter 26.

[0102] Furthermore, for example, in Modification 2, the voltage obtained by subtracting a certain value from the voltage at the output terminal of the second DC-DC converter 26 is set as the voltage indication value of the second DC-DC converter 26. That is, the voltage value that is always lower than the voltage at the output terminal of the first DC-DC converter 25, which is connected to the auxiliary equipment 32 together with the second DC-DC converter 26, becomes the voltage indication value of the second DC-DC converter 26. As a result, the first DC-DC converter 25 outputs power preferentially over the second DC-DC converter 26.

[0103] [Remark]

[0104] Furthermore, the various processes executed by the CPU 20A after reading the software (program) in the above embodiments can be executed by various processors other than the CPU. Examples of processors in this case include FPGAs (Field-Programmable Gate Arrays) and processors with dedicated circuit structures designed for specific processes, such as PLDs (Programmable Logic Devices) and ASICs (Application Specific Integrated Circuits), whose circuit structures can be modified after manufacturing. Additionally, the aforementioned processes can be executed by one of these various processors, or by a combination of two or more processors of the same or different types (e.g., multiple FPGAs, or a combination of a CPU and an FPGA). Moreover, the hardware structure of these various processors is more specifically a circuit that incorporates circuit elements such as semiconductor components.

[0105] Furthermore, in the above embodiments, the description assumes that each program is pre-stored (installed) on a computer-readable non-transitory recording medium. For example, the control program 100 in ECU 20 is pre-stored in ROM 20B. However, this is not a limitation; each program may also be provided on a non-transitory recording medium such as CD-ROM (Compact Disc Read Only Memory), DVD-ROM (Digital Versatile Disc Read Only Memory), and USB (Universal Serial Bus) memory. Alternatively, the program may be downloaded from an external device via a network.

[0106] The processing flow described in the above embodiments is also an example. Without departing from the main idea, useless steps can be deleted, new steps can be added, and the processing order can be changed.

Claims

1. A control device for controlling a first DC-DC converter and a second DC-DC converter supplying power to a device, wherein the outputs of the first DC-DC converter and the second DC-DC converter are connected in parallel, wherein... The control device includes a control unit that fixes the output of the first DC-DC converter to its maximum when the output of the first DC-DC converter is at its maximum, and performs feedback control in a manner that ensures the output of the second DC-DC converter meets predetermined conditions. When the voltage indication value of the first DC-DC converter is less than the maximum value, the control unit performs feedback control in such a way that the voltage indication value of the first DC-DC converter becomes the target value, and controls the voltage indication value of the second DC-DC converter to be a value lower than the voltage indication value of the first DC-DC converter by a predetermined value. When the voltage indication value of the first DC-DC converter reaches its maximum value, the control unit controls the first DC-DC converter so that its voltage indication value is at its maximum value, and performs feedback control so that the voltage indication value of the second DC-DC converter is at its target value.

2. The control device according to claim 1, wherein, When the voltage indication value of the first DC-DC converter is less than the maximum value, the control unit performs feedback control in such a way that the voltage indication value of the first DC-DC converter becomes the target value, and performs feedback control in such a way that the voltage indication value of the second DC-DC converter becomes a value that is lower than the target value by a predetermined value.

3. The control device according to claim 1, wherein, When the voltage indication value of the first DC-DC converter is less than the maximum value and a specific load is generated in the device, the control unit performs feedback control in such a way that the voltage indication value of the first DC-DC converter becomes the target value, and performs feedback control in such a way that the voltage indication value of the second DC-DC converter becomes a value that is lower than the target value by a predetermined amount.

4. The control device according to any one of claims 1 to 3, wherein, The specified value is set to take into account the deviation of the output of the DC-DC converter.

5. The control device according to claim 4, wherein, The specified value is set to take into account the minimum voltage difference that should be ensured.

6. A vehicle, wherein, have: The control device according to any one of claims 1 to 5; A high-voltage battery supplies power to both the first and second DC-DC converters; and An auxiliary battery supplies power to the device and receives power from the first DC-DC converter and the second DC-DC converter, respectively.

7. A control method for controlling a first DC-DC converter and a second DC-DC converter supplying power to a device, wherein the outputs of the first DC-DC converter and the second DC-DC converter are connected in parallel, wherein... The control method causes the computer to perform the following processing: When the output of the first DC-DC converter is at its maximum, the output of the first DC-DC converter is fixed at its maximum, and feedback control is performed in a manner that ensures the output of the second DC-DC converter meets specified conditions. If the voltage indication value of the first DC-DC converter is less than the maximum value, feedback control is performed so that the voltage indication value of the first DC-DC converter becomes the target value, and the voltage indication value of the second DC-DC converter is controlled to be a value lower than the voltage indication value of the first DC-DC converter by a predetermined value. When the voltage indication value of the first DC-DC converter reaches its maximum value, control is performed in such a way that the voltage indication value of the first DC-DC converter reaches its maximum value, and feedback control is performed in such a way that the voltage indication value of the second DC-DC converter reaches its target value.

8. A non-transitory recording medium recording a control program for controlling a first DC-DC converter and a second DC-DC converter supplying power to a device, wherein the outputs of the first DC-DC converter and the second DC-DC converter are connected in parallel, wherein... The control program causes the computer to perform the following processes: When the output of the first DC-DC converter is at its maximum, the output of the first DC-DC converter is fixed at its maximum, and feedback control is performed in a manner that ensures the output of the second DC-DC converter meets specified conditions. If the voltage indication value of the first DC-DC converter is less than the maximum value, feedback control is performed so that the voltage indication value of the first DC-DC converter becomes the target value, and the voltage indication value of the second DC-DC converter is controlled to be a value lower than the voltage indication value of the first DC-DC converter by a predetermined value. When the voltage indication value of the first DC-DC converter reaches its maximum value, control is performed in such a way that the voltage indication value of the first DC-DC converter reaches its maximum value, and feedback control is performed in such a way that the voltage indication value of the second DC-DC converter reaches its target value.

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