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

Abstract

A control device according to the present invention is a control device for controlling a first DC-DC converter and a second DC-CDC converter that supplies power to a device, and includes: a determination unit that determines whether a predetermined condition is satisfied; and a control unit that, when the determination unit determines that the predetermined condition is satisfied, switches control of the DC-CDC converter that preferentially supplies power to the device.

Description

Technical Field

[0001] The present disclosure relates to a control device, a vehicle, a control method, and a recording medium having a control program recorded thereon. Background Art

[0002] Japanese Patent No. 5387651 discloses a power supply system that coordinately controls a plurality of DCDC converters.

[0003] If only one DCDC converter is used, the power consumption may be biased towards that DCDC converter, causing premature failure. Summary of the Invention

[0004] An object of the present disclosure is to provide a control device, a vehicle, a control method, and a recording medium having a control program recorded thereon, which suppress the early occurrence of a failure by utilizing a plurality of DC-DC converters in a well-balanced manner.

[0005] A first embodiment of a control device is a control device that controls a first DCDC converter and a second DCDC converter that supplies power to a device, wherein the control device includes: a determination unit that determines whether a predetermined condition is satisfied; and a control unit that controls switching the DCDC converter that preferentially supplies power to the device when the determination unit determines that the predetermined condition is satisfied.

[0006] A control device in a first embodiment controls a first DC-DC converter and a second DC-DC converter. The first DC-DC converter and the second DC-CDC converter are each configured to supply power to the same device. In this control device, a determination unit determines whether a predetermined condition is satisfied. If the predetermined condition is satisfied, the control unit switches the DC-CDC converter that preferentially supplies power to the device. This control device switches the DC-CDC converter to be used preferentially based on the predetermined condition, enabling balanced utilization of the DC-CDC converters and preventing premature failures.

[0007] The control device of the second aspect is configured as follows: in addition to the control device of the first aspect, when the temperature involved in the above-mentioned first DCDC converter rises and reaches the first temperature, the above-mentioned determination unit determines that a predetermined condition is satisfied, and the above-mentioned control unit switches the main DCDC converter that prioritizes power supply from the above-mentioned first DCDC converter to the above-mentioned second DCDC converter.

[0008] In the control device of the second aspect, when the temperature of the first DCDC converter rises and reaches the first temperature, the control device switches to the second DCDC converter, thereby preventing the first DCDC converter from being used more heavily.

[0009] The control device of the third aspect is configured as follows: in addition to the control device of the second aspect, when the temperature related to the above-mentioned first DCDC converter decreases and reaches a second temperature lower than the above-mentioned first temperature, the above-mentioned determination unit determines that a predetermined condition is satisfied, and the above-mentioned control unit switches the main DCDC converter that prioritizes power supply from the above-mentioned second DCDC converter to the above-mentioned first DCDC converter.

[0010] In the third aspect of the control device, the second temperature, which serves as a condition for switching from the second DCDC converter to the first DCDC converter due to a decrease in the temperature of the first DCDC converter, is set to a temperature lower than the first temperature. In other words, this control device provides a temperature difference between the conditions for switching from the first DCDC converter to the second DCDC converter and the conditions for switching from the second DCDC converter to the first DCDC converter. Therefore, this control device can suppress oscillation caused by frequent switching between the two DCDC converters.

[0011] A control device according to a fourth aspect is configured as the control device according to any one of the first to third aspects, wherein the control unit gradually increases the output power of the slave DCDC converter and then reduces the output power of the master DCDC converter to switch the DCDC converter that prioritizes power supply.

[0012] According to the control device of the fourth aspect, by gradually increasing the output of the slave DCDC converter and switching to the master DCDC converter, it is possible to suppress a sudden change in the power supplied to the device when switching the DCDC converter.

[0013] The control device of the fifth aspect is configured as follows: based on the control device described in technical solution 4, when switching the DCDC converter that prioritizes power supply, after gradually increasing the voltage indication value of the slave DCDC converter, when the voltage indication value of the slave DCDC converter reaches the voltage indication value of the master DCDC converter, the above-mentioned control unit controls the voltage indication value of the master DCDC converter to a value lower than the voltage indication value of the slave DCDC converter.

[0014] According to the control device of the fifth aspect, by performing switching control of the DCDC converters based on the voltage instruction values of the respective DCDC converters, it is possible to suppress a sudden change in the voltage of the device and ensure the stability of the operation of the device.

[0015] A control device according to a sixth aspect is configured as follows: in addition to the control device according to any one of the first to fifth aspects, when the voltage indicated value of the main DCDC converter is less than a maximum value, the control unit performs feedback control so that the voltage indicated value of the main DCDC converter becomes a target value, and controls the voltage indicated value of the slave DCDC converter to a value lower than the voltage indicated value of the main DCDC converter; and when the voltage indicated value of the main DCDC converter reaches a maximum value, the control unit performs control so that the voltage indicated value of the main DCDC converter becomes the maximum value, and performs feedback control so that the voltage indicated value of the slave DCDC converter becomes the target value.

[0016] The target value may be, for example, a reference voltage value of a battery supplied to the device. According to the control device of the sixth aspect, when the output of the main DCDC converter is maximized, the voltage of the device can be maintained by feedback control using the slave DCDC converter.

[0017] A vehicle according to a seventh aspect comprises: a control device according to any one of the first to sixth aspects; a high-voltage battery that supplies power to each of the first and second DC-DC converters; and an auxiliary battery that supplies power to the aforementioned equipment and receives power from each of the first and second DC-CDC converters.

[0018] According to the vehicle of the seventh aspect, by switching the DCDC converter to be used preferentially in response to a predetermined condition, it is possible to suppress unbalanced use of one DCDC converter and stabilize the voltage of the auxiliary battery.

[0019] The eighth form of the control method is a control method for controlling a first DCDC converter and a second DCDC converter that supplies power to a device, wherein a computer performs the following processing: determining whether a prescribed condition is satisfied, and switching control of the DCDC converter that preferentially supplies power to the above-mentioned device when it is determined that the prescribed condition is satisfied.

[0020] An eighth aspect of the control method is a method for controlling a first DCDC converter and a second DCDC converter. As described above, the first DCDC converter and the second DCDC converter are each configured to supply power to the same device. In this control method, a computer determines whether a predetermined condition is satisfied. If the predetermined condition is satisfied, the computer switches the DCDC converter that preferentially supplies power to the device. This control method achieves balanced utilization of the DCDC converters by switching the prioritized DCDC converter in response to the predetermined condition, thus preventing premature failures.

[0021] A ninth aspect is a non-transitory recording medium having a control program recorded thereon. The control program controls a first DC-DC converter and a second DC-DC converter that supply power to a device, wherein the control program causes a computer to execute a process of determining whether a predetermined condition is satisfied and, if the predetermined condition is satisfied, switching control of the DC-DC converter that preferentially supplies power to the device.

[0022] A control program recorded on a non-transitory recording medium in the ninth aspect causes a computer to control a first DC-DC converter and a second DC-DC converter. As described above, the first DC-DC converter and the second DC-CDC converter are each configured to supply power to the same device. Based on this program, the computer determines whether a predetermined condition is met. If the predetermined condition is met, the computer switches the DC-CDC converter that preferentially supplies power to the device. By using this program, the computer switches the DC-CDC converter to be used preferentially based on the predetermined condition, achieving balanced utilization of the DC-CDC converters and preventing premature failures.

[0023] According to the present disclosure, by utilizing a plurality of DCDC converters in a well-balanced manner, it is possible to suppress the early occurrence of failures. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Exemplary embodiments of the present disclosure will be described in detail based on the following drawings, wherein:

[0025] Figure 1 It is a schematic configuration diagram of a vehicle and a power supply system according to the first embodiment.

[0026] Figure 2 This is a block diagram showing the configuration of a ROM in the ECU according to the first embodiment.

[0027] Figure 3 This is a block diagram showing the functional configuration of the CPU in the ECU according to the first embodiment.

[0028] Figure 4 This is a flowchart showing the flow of the power control process in the first embodiment.

[0029] Figure 5 This is a flowchart showing the flow of power control processing in the first embodiment (followed by Figure 4 ).

[0030] Figure 6 This is a flowchart showing the flow of the transition process in the first embodiment.

[0031] Figure 7 This is a flowchart showing the flow of transition processing in the second embodiment. DETAILED DESCRIPTION

[0032] Hereinafter, an example of an embodiment of the present disclosure will be described in detail with reference to the drawings.

[0033] [First embodiment]

[0034] (structure)

[0035] like Figure 1 As shown, the power supply system 10 of the first embodiment is mounted on a vehicle 12. The vehicle 12 is exemplified by an EV (Electric Vehicle) or an HV (Hybrid Vehicle). The vehicle 12 of this embodiment is supplied with electric power via the power supply system 10. The vehicle 12 includes auxiliary machines 32, which are devices that operate various components of the vehicle 12, and an ECU group 34 that controls various components of the vehicle 12, including the auxiliary machines 32.

[0036] The power supply system 10 includes an ECU 20 as a control device, a high-voltage battery 22, a DC-DC converter 24, and an auxiliary battery 28. The details of the ECU 20 will be described later. The DC-DC converter 24 of this embodiment includes a first DC-DC converter 25 and a second DC-DC converter 26.

[0037] The high-voltage battery 22 is a high-voltage battery used to operate the driving motor of the vehicle 12 and is composed of 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 .

[0038] The first DC-DC converter 25 supplies power output from the high-voltage battery 22 to the auxiliary battery 28 and the auxiliary equipment 32. The first DC-DC converter 25 has the high-voltage battery 22 connected to its input side and the auxiliary battery 28 and the auxiliary equipment 32 connected to its output side. When supplying power, the first DC-CDC converter 25 steps down the output voltage of the high-voltage battery 22, which serves as its input voltage, to a predetermined voltage based on instructions from the ECU 20, and then outputs the voltage to the auxiliary battery 28 and the auxiliary equipment 32.

[0039] The second DC-DC converter 26 has the same function as the first DC-DC converter 25. Specifically, it supplies the electric power output from the high-voltage battery 22 to the auxiliary battery 28 and the auxiliary devices 32. The second DC-DC converter 26 has the high-voltage battery 22 connected to its input side and the auxiliary battery 28 and the auxiliary devices 32 connected to its output side. When supplying electric power, the second DC-CDC converter 26 steps down the output voltage of the high-voltage battery 22, which serves as its input voltage, to a predetermined voltage based on instructions from the ECU 20, and then outputs the resulting power to the auxiliary battery 28 and the auxiliary devices 32.

[0040] Furthermore, in the power supply system 10 of the present embodiment, the DCDC converter 24 that supplies power preferentially to the auxiliary machines 32 is controlled by the ECU 20 described later.

[0041] The auxiliary battery 28 is a battery capable of operating the auxiliary devices 32 and is comprised of a rechargeable and dischargeable 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 the first and second DC-DC converters 25 and 26. Furthermore, the auxiliary battery 28 is connected to the auxiliary devices 32 of the vehicle 12 to supply power to the auxiliary devices 32.

[0042] ECU 20 is constituted by, for example, a microcomputer and has a function of controlling first and second DCDC converters 25 and 26 . ECU 20 thereby supplies power from high-voltage battery 22 to auxiliary battery 28 and auxiliary devices 32 via first and second DCDC converters 25 and 26 .

[0043] ECU 20 includes a CPU (Central Processing Unit) 20A, a ROM (Read Only Memory) 20B, a RAM (Random Access Memory) 20C, an input / output interface (I / F) 20D, and a communication I / F 20E. CPU 20A, ROM 20B, RAM 20C, I / O I / F 20D, and communication I / F 20E are interconnected for communication via an internal bus 20F. CPU 20A is an example of a processor, and RAM 20C is an example of a memory.

[0044] The CPU 20A is a central processing unit that executes various programs and controls various components. Specifically, the CPU 20A reads programs from the ROM 20B and executes the programs using the RAM 20C as a work area.

[0045] The ROM 20B as a storage unit stores various programs and various data. Figure 2 As shown, the ROM 20B of this embodiment stores a control program 100 and setting data 110 .

[0046] The control program 100 is a program for controlling the ECU 20. The ECU 20 controlled by the control program controls the first DCDC converter 25 and the second DCDC converter 26.

[0047] The setting data 110 stores control parameters for feedback control in each DCDC converter. Furthermore, the setting data 110 stores setting values for a first temperature that serves as a condition for switching from the first DCDC converter 25 to the second DCDC converter 26, and a second temperature that serves as a condition for switching from the second DCDC converter 26 to the first DCDC converter 25.

[0048] like Figure 1 As shown, the RAM 20C serves as a working area to temporarily store programs or data.

[0049] The input / output I / F 20D is an interface for communicating with the first DCDC converter 25 and the second DCDC converter 26 .

[0050] The communication I / F 20E is an interface for connecting to the ECU group 34. This interface uses, for example, a communication standard based on the CAN protocol. The communication I / F 20E is connected to the external bus 20H. Thus, the ECU 20 can obtain the operating status of each component of the vehicle 12 via the communication I / F 20E.

[0051] Furthermore, the ECU 20 may include a storage device as a storage unit in addition to or in place of the ROM 20B. The storage device may be formed of, for example, a HDD (Hard Disk Drive) or an SSD (Solid State Drive).

[0052] like Figure 3 As shown, in the ECU 20 of the present embodiment, the CPU 20A functions as an acquisition unit 200 , a determination unit 210 , and a control unit 220 by executing the control program 100 .

[0053] The acquisition unit 200 has the function of acquiring the respective states of the first DC-DC converter 25 and the second DC-DC converter 26. The states acquired from each DC-DC converter 24 include the output voltage and cooling water temperature of each DC-DC converter 24. Furthermore, the acquisition unit 200 acquires the voltage of the auxiliary battery 28. Furthermore, the acquisition unit 200 can acquire the operating states of various components in the vehicle 12, including the auxiliary devices 32, from the ECU group 34.

[0054] Determination unit 210 has a function for determining whether predetermined conditions for switching the prioritized DCDC converter 24 are satisfied. These predetermined conditions include switching condition 1, which is a condition for switching from the first DCDC converter 25 to the second DCDC converter 26, and switching condition 2, which is a condition for switching from the second DCDC converter 26 to the first DCDC converter 25. Determination unit 210 in this embodiment determines that switching condition 1 is satisfied when the cooling water temperature of the first DCDC converter 25 rises and reaches a first temperature. Determination unit 210 determines that switching condition 2 is satisfied when the temperature of the first DCDC converter 25 decreases and reaches a second temperature that is a predetermined value T lower than the first temperature.

[0055] If the value of T is set too low, the priority DCDC converter 24 will be frequently replaced during the transition process described later. Therefore, the value of T is set to a value that does not frequently replace the priority DCDC converter 24 and does not excessively favor either the first DCDC converter 25 or the second DCDC converter 26. When determining that switching condition 1 or switching condition 2 has been newly satisfied, determination unit 210 changes the control flag. Specifically, when switching condition 1 is satisfied, determination unit 210 changes the control flag from 0 to 1, and when switching condition 2 is satisfied, it changes the control flag from 1 to 0.

[0056] The control unit 220 performs power control processing to control the output of each DCDC converter 24. Here, the DCDC converter 24 that is prioritized for power supply is referred to as the master DCDC converter 24, and the DCDC converter 24 prioritized by the master DCDC converter 24 is referred to as the slave DCDC converter 24. In this embodiment, the control unit 220 adjusts the output power by adjusting the voltage command value for each DCDC converter 24. Normally, the control unit 220 sets a voltage command value for the slave DCDC converter 24 that is lower by a predetermined value V than that of the master DCDC converter 24, thereby controlling the output of the master DCDC converter 24.

[0057] If the value of V is set too high, the voltage supported by the output of the second DCDC converter 26 will decrease if the load on the auxiliary equipment 32 increases and the output of the first DCDC converter 25 is insufficient. If the value of V is set too low, the output order will be disrupted due to variations in the outputs of the two DCDC converters 24, and the originally assumed priority output of the DCDC converter 24 will not be achieved. Therefore, in this embodiment, V is set within a range that is less likely to cause the above-mentioned problems.

[0058] Furthermore, the control unit 220 performs a transition process when switching the DCDC converter 24. Details of the transition process will be described later.

[0059] (Control process)

[0060] use Figures 4 to 6 The flowchart of FIG. 1 illustrates the flow of processing executed by ECU 20 of this embodiment. The processing in ECU 20 is implemented by CPU 20A functioning as the aforementioned acquisition unit 200, determination unit 210, and control unit 220. In the drawings, "DCDC converter" is abbreviated as "DDC," and "feedback control" is abbreviated as "FB control."

[0061] First, yes Figure 4 and Figure 5 The power control process as a control method controls the output by setting the voltage instruction value of each DCDC converter 24.

[0062] exist Figure 4 In step S100 , the CPU 20A sets the power instruction value of the first DCDC converter 25 to an initial value, and also sets the power instruction value of the second DCDC converter 26 to an initial value.

[0063] In step S101, the CPU 20A determines whether the control flag is 1. If the CPU 20A determines that the control flag is 1 (if the answer is yes in step S101), the CPU 20A proceeds to step S101 according to the connector A. Figure 5 On the other hand, when CPU 20A determines that the control flag is not 1 (in the case of NO in step S101), the process proceeds to step S102.

[0064] In step S102, the CPU 20A determines whether the switching condition 1 is satisfied. In this embodiment, the switching condition 1 is set when the cooling water temperature of the first DCDC converter 25 reaches a preset first temperature. If the CPU 20A determines that the switching condition 1 is satisfied (if the answer is yes in step S102), the CPU 20A proceeds to step 103 according to the connector B. Figure 5 On the other hand, when CPU 20A determines that the switching condition 1 is not satisfied (in the case of NO in step S102 ), the process proceeds to step S103 .

[0065] In step S103 , the CPU 20A sets the control flag to 0.

[0066] In step S104, the 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 the CPU 20A determines that the voltage indication value of the first DC-DC converter 25 is greater than or equal to the maximum value (if the answer is yes in step S104), the process proceeds to step S106. On the other hand, if the CPU 20A determines that the voltage indication value of the first DC-DC converter 25 is not greater than or equal to the maximum value, that is, is less than the maximum value (if the answer is no in step S104), the process proceeds to step S105.

[0067] In step S105 , the CPU 20A sets the voltage command value of the first DCDC converter 25 so as to perform feedback control based on the target voltage value of the auxiliary battery 28 , and sets the voltage command value of the second DCDC converter 26 to a value obtained by subtracting the voltage command value of the first DCDC converter 25 from V. Then, the process returns to step S101 according to connector D.

[0068] In step S106, the CPU 20A determines whether the voltage command value of the second DC-DC converter 26 is equal to the voltage command value -V of the first DC-DC converter 25. If the CPU 20A determines that the voltage command value of the second DC-DC converter 26 is less than the voltage command value -V of the first DC-CDC converter 25 (if the answer is "Yes" in step S106), the process proceeds to step S105. On the other hand, if the CPU 20A determines that the voltage command value of the second DC-CDC converter 26 is equal to or greater than the voltage command value -V of the first DC-CDC converter 25 (if the answer is "No" in step S106), the process proceeds to step S107.

[0069] In step S107, CPU 20A sets the voltage command value of first DCDC converter 25 to the maximum value and sets the voltage command value of second DCDC converter 26 to perform feedback control based on the target voltage value of auxiliary battery 28. Then, according to connector D, the process returns to step S101.

[0070] exist Figure 5 In step S108, the CPU 20A determines whether the switching condition 2 is satisfied. In this embodiment, the switching condition 2 is set when the cooling water temperature of the first DCDC converter 25 reaches a second temperature lower than the first temperature, which is a preset temperature. If the CPU 20A determines that the switching condition 2 is satisfied (if the answer is yes in step S108), the CPU 20A proceeds to step C according to the connector. Figure 4On the other hand, when CPU 20A determines that the switching condition 2 is not satisfied (in the case of NO in step S108), the process proceeds to step S109.

[0071] In step S109 , the CPU 20A sets the control flag to 1.

[0072] In step S110, the CPU 20A determines whether the voltage indication value of the second DC-DC converter 26 is greater than or equal to the maximum value. If the CPU 20A determines that the voltage indication value of the second DC-DC converter 26 is greater than or equal to the maximum value (if the answer is yes in step S110), the process proceeds to step S112. On the other hand, if the CPU 20A determines that the voltage indication value of the second DC-DC converter 26 is not greater than or equal to the maximum value, that is, is less than the maximum value (if the answer is no in step S110), the process proceeds to step S111.

[0073] In step S111, the CPU 20A sets the voltage instruction value of the first DCDC converter 25 to a value obtained by setting the voltage instruction value of the second DCDC converter 26 to -V, and sets the voltage instruction value of the second DCDC converter 26 to perform feedback control based on the target voltage value of the auxiliary battery 28. Figure 4 Step S101.

[0074] In step S112, the CPU 20A determines whether the voltage command value of the first DC-DC converter 25 is less than the value obtained by the voltage command value -V of the second DC-DC converter 26. If the CPU 20A determines that the voltage command value of the first DC-DC converter 25 is less than the value obtained by the voltage command value -V of the second DC-CDC converter 26 (if the answer is yes in step S112), the process proceeds to step S111. On the other hand, if the CPU 20A determines that the voltage command value of the first DC-DC converter 25 is not less than the value obtained by the voltage command value -V of the second DC-CDC converter 26, that is, is greater than or equal to the value obtained by the voltage command value -V of the second DC-CDC converter 26 (if the answer is no in step S112), the process proceeds to step S113.

[0075] In step S113 , CPU 20A sets the voltage command value of first DCDC converter 25 and sets the voltage command value of second DCDC converter 26 to the maximum value so as to perform feedback control based on the target voltage value of auxiliary battery 28 .

[0076] As described above, the functions of the power control process can be summarized as follows: Under normal conditions, when there is margin in the output of the main DC-DC converter 24, the power command value of the main DC-DC converter 24 is feedback-controlled based on the target voltage value of the auxiliary battery 28 to maintain the voltage supplied to the auxiliary devices 32 (see steps S105 and S111).

[0077] On the other hand, when the output of the master DCDC converter 24 reaches its maximum overload, the power command value of the master DCDC converter 24 is maximized, and feedback control of the power command value of the slave DCDC converter 24 is performed based on the target voltage value of the auxiliary battery 28 to maintain the voltage supplied to the auxiliary devices 32 (see steps S107 and S113). If the overload condition occurs, the voltage of the auxiliary devices 32 decreases. However, if the load on the auxiliary devices 32 subsequently decreases, the voltage of the auxiliary devices 32 approaches the voltage command value of the master DCDC converter 24 (i.e., the maximum value). As a result, the power command value of the slave DCDC converter 24, which is currently undergoing feedback control, decreases, returning to normal control (see steps S106 and S112).

[0078] Furthermore, in the power control process, if switching condition 1 is satisfied, the priority DCDC converter 24 is switched from the first DCDC converter 25 to the second DCDC converter 26. If switching condition 2 is satisfied, the priority DCDC converter 24 is switched from the second DCDC converter 26 to the first DCDC converter 25. During this switching, the following transition process is performed.

[0079] Next, use Figure 6 The following describes a transition process when the prioritized DCDC converter 24 is switched from the first DCDC converter 25 to the second DCDC converter 26. Note that switching from the second DCDC converter 26 to the first DCDC converter 25 can be performed by replacing the first DCDC converter 25 and the second DCDC converter 26 in the flowchart, so the description is omitted.

[0080] exist Figure 6In step S200, the CPU 20A determines whether the power indication value of the first DCDC converter 25 is greater than or equal to the power indication value of the second DCDC converter 26. If the CPU 20A determines that the power indication value of the first DCDC converter 25 is greater than or equal to the power indication value of the second DCDC converter 26 (if the answer is yes in step S200), the process proceeds to step S201. On the other hand, if the CPU 20A determines that the power indication value of the first DCDC converter 25 is not greater than or equal to the power indication value of the second DCDC converter 26, that is, that the power indication value of the first DCDC converter 25 is less than the power indication value of the second DCDC converter 26 (if the answer is no in step S200), the process proceeds to step S202.

[0081] In step S201, the CPU 20A sets the voltage command value of the first DC-DC converter 25 to perform feedback control based on the target voltage value of the auxiliary battery 28. It also sets the voltage command value of the second DC-DC converter 26 to the previously set value + α. The initial values of the previously set values are the values set in steps S105 and S107 of the power control process described above. Furthermore, the added value α is set to a value sufficiently smaller than the voltage command value of each DC-DC converter 24, for example, a value less than 1 / 10. The process then returns to step S200.

[0082] In step S202, the CPU 20A determines whether the voltage indication value of the second DC-DC converter 26 is greater than or equal to the maximum value. If the CPU 20A determines that the voltage indication value of the second DC-DC converter 26 is greater than or equal to the maximum value (if the answer is yes in step S202), the process proceeds to step S204. On the other hand, if the CPU 20A determines that the voltage indication value of the second DC-DC converter 26 is not greater than or equal to the maximum value, that is, is less than the maximum value (if the answer is no in step S202), the process proceeds to step S203.

[0083] In step S203 , CPU 20A sets the voltage command value of first DCDC converter 25 to a value obtained by setting the voltage command value of second DCDC converter 26 to -V, and also sets the voltage command value of second DCDC converter 26 to perform feedback control based on the target voltage value of auxiliary battery 28 . CPU 20A then terminates the transition process.

[0084] In step S204 , CPU 20A sets the voltage command value of first DCDC converter 25 and sets the voltage command value of second DCDC converter 26 to the maximum value so as to perform feedback control based on the target voltage value of auxiliary battery 28 . CPU 20A then ends the transition process.

[0085] (Summary of Implementation Methods)

[0086] In the power supply system 10 of this embodiment, the ECU 20 is configured to control the first DCDC converter 25 and the second DCDC converter 26 that supply power to the auxiliary devices 32. In the ECU 20 of this embodiment, a determination unit 210 determines whether a predetermined condition is satisfied. If the predetermined condition is satisfied, the control unit 220 switches the DCDC converter 24 that preferentially supplies power to the auxiliary devices 32. According to this embodiment, by switching the prioritized DCDC converter 24 in response to the predetermined condition, balanced utilization of the first and second DCDC converters 25, 26 is achieved, thereby preventing premature failures.

[0087] Furthermore, in vehicle 12 of the present embodiment, the voltage of auxiliary battery 28 can be stabilized by switching DCDC converter 24 to be used preferentially in response to a predetermined condition.

[0088] The ECU 20 of this embodiment is configured to switch the DCDC converter 24 being used preferentially to the second DCDC converter 26 when the cooling water temperature of the first DCDC converter 25 rises and reaches a first temperature while the first DCDC converter 25 is being used preferentially. This can prevent the first DCDC converter 25 from being used more frequently in the power supply system 10.

[0089] Furthermore, in the ECU 20 of the present embodiment, the second temperature at which the cooling temperature of the first DCDC converter 25 is lowered and the second DCDC converter 26 is switched to the first DCDC converter 25 is set to a temperature lower than the first temperature. According to the present embodiment, by providing a temperature difference between the conditions for switching from the first DCDC converter 25 to the second DCDC converter 26 and the conditions for switching from the second DCDC converter 26 to the first DCDC converter 25, oscillation caused by frequent switching between the two DCDC converters 24 can be suppressed.

[0090] Furthermore, when the voltage command value of the main DCDC converter 24 is less than the maximum value, the ECU 20 of the present embodiment performs feedback control so that the voltage command value of the main DCDC converter 24 reaches the target value of the voltage of the auxiliary battery 28, and controls the voltage command value of the slave DCDC converter 24 to a value lower than the voltage command value of the main DCDC converter 24. On the other hand, when the voltage command value of the main DCDC converter 24 reaches the maximum value, the ECU 20 performs control so that the voltage command value of the main DCDC converter 24 reaches the maximum value, and performs feedback control so that the voltage command value of the slave DCDC converter 24 reaches the target value of the voltage of the auxiliary battery 28.

[0091] As described above, according to this embodiment, when the output of main DCDC converter 24 reaches a maximum, feedback control is performed so that the voltage command value of DCDC converter 24 becomes the target value of the voltage of auxiliary battery 28 , thereby maintaining the voltage of auxiliary devices 32 .

[0092] Furthermore, according to this embodiment, when performing the switching process of the DCDC converter 24 , the output of the slave DCDC converter 24 is gradually increased to switch to the master DCDC converter 24 , thereby suppressing a sudden change in the power supplied to the auxiliary devices 32 when switching the DCDC converter 24 .

[0093] In particular, in this embodiment, switching control of the DCDC converters 24 is performed based on the voltage command values of the respective DCDC converters 24, thereby suppressing abrupt changes in the voltage of the auxiliary devices 32. This ensures operational stability of the auxiliary devices 32.

[0094] [Second embodiment]

[0095] The second embodiment differs from the first embodiment in the flow of the transition process. The configuration of the power supply system 10 of this embodiment is the same as that of the first embodiment, and the same reference numerals denote the same configuration, and detailed descriptions thereof will be omitted.

[0096] Below, use Figure 7 The transition process of this embodiment will be described. Note that this figure shows an example in which the prioritized DCDC converter 24 is switched from the first DCDC converter 25 to the second DCDC converter 26. Furthermore, when switching from the second DCDC converter 26 to the first DCDC converter 25, the first and second DCDC converters 25, 26 in the flowchart can be replaced, and therefore, description thereof will be omitted.

[0097] exist Figure 7 In step S300, CPU 20A sets the voltage command value of first DC-DC converter 25 so as to perform feedback control based on the target voltage value of auxiliary battery 28, and sets the voltage command value of second DC-DC converter 26 so as to perform feedback control based on the target voltage value of auxiliary battery 28 + α. Furthermore, as described above, the added value α is set to a value sufficiently smaller than the voltage command value of each DC-DC converter 24, for example, a value smaller than 1 / 10.

[0098] In step S301 , the CPU 20A sets a counter to zero.

[0099] In step S302, the CPU 20A determines whether the counter is equal to or greater than a certain value t. If the CPU 20A determines that the counter is equal to or greater than the certain value t (if the answer is yes in step S302), the process proceeds to step S304. On the other hand, if the CPU 20A determines that the counter is not equal to or greater than the certain value t, that is, that the counter is less than the certain value t (if the answer is no in step S302), the process proceeds to step S303.

[0100] In step S303 , the CPU 20A adds one control cycle to the counter and then returns to step S302 .

[0101] In step S304 , CPU 20A sets the voltage command value of first DCDC converter 25 so as to perform feedback control based on a target voltage value −V of auxiliary battery 28 , and sets the voltage command value of second DCDC converter 26 so as to perform feedback control based on a target voltage value +α of auxiliary battery 28 .

[0102] In step S305 , the CPU 20A sets the counter to zero.

[0103] In step S306, the CPU 20A determines whether the counter has reached or exceeded a certain value t. If the CPU 20A determines that the counter has reached or exceeded the certain value t (if the answer is yes in step S306), the process proceeds to step S308. On the other hand, if the CPU 20A determines that the counter is not greater than the certain value t, that is, that the counter is less than the certain value t (if the answer is no in step S306), the process proceeds to step S307.

[0104] In step S307 , the CPU 20A adds one control cycle to the counter and then returns to step S306 .

[0105] In step S308 , CPU 20A sets the voltage command value of first DCDC converter 25 so as to perform feedback control based on the target voltage value −V of auxiliary battery 28 , and sets the voltage command value of second DCDC converter 26 so as to perform feedback control based on the target voltage value of auxiliary battery 28 .

[0106] According to this embodiment, the same effects as those of the first embodiment can be achieved. In particular, according to this embodiment, feedback control is performed both when the voltage command value is increased and when the voltage command value is decreased. This further reduces the abrupt change in the voltage of the auxiliary equipment 32 when the DCDC converter 24 is switched.

[0107] (Variation)

[0108] In the above-described embodiment, a threshold value is set for the cooling temperature of the first DCDC converter 25 as the "predetermined condition" that triggers the switching of the DCDC converter 24. Specifically, a first temperature is set as the threshold value for the switching condition 1 for switching from the first DCDC converter 25 to the second DCDC converter 26, and a second temperature is set as the threshold value for the switching condition 2 for switching from the second DCDC converter 26 to the first DCDC converter 25. However, the "predetermined condition" that triggers the switching of the DCDC converter 24 is not limited to this.

[0109] For example, in Modification 1, a threshold value for the element temperature of the first DCDC converter 25 can be set as the "predetermined condition." In this case, similar to the above-described embodiment, a first temperature is set as the threshold value for switching condition 1, and a second temperature is set as the threshold value for switching condition 2. Also in this modification, similar to the above-described embodiment, oscillation caused by frequent switching between the two DCDC converters 24 can be suppressed.

[0110] For example, in Modification 2, a "predetermined condition" based on the relationship between the element temperature of the first DCDC converter 25 and the element temperature of the second DCDC converter 26 can be set. In this case, for example, switching condition 1 can be set when the element temperature of the first DCDC converter 25 exceeds the element temperature of the second DCDC converter 26. On the other hand, switching condition 2 can be set when the element temperature of the first DCDC converter 25 falls below the element temperature -T of the second DCDC converter 26. Furthermore, as described above, by setting the value of T to a value that does not excessively favor either the first DCDC converter 25 or the second DCDC converter 26 as the preferred DCDC converter 24, oscillation caused by frequent switching between the two DCDC converters 24 can be suppressed, similar to the above-described embodiment.

[0111] For example, in Modification 3, the activation and deactivation of auxiliary machines 32 constituting any load in the vehicle 12 can be set as "predetermined conditions." In this case, the activation of any load can be set as Switching Condition 1, while the deactivation of any load can be set as Switching Condition 2. According to this Modification, by appropriately selecting any load, specifically, by appropriately selecting a combination of activated auxiliary machines 32, it is possible to prevent the use of a single DC-DC converter 24 from being overweight.

[0112] [Remark]

[0113] In addition, the various processes executed by CPU 20A reading the software (program) in the above-mentioned embodiment may also be executed by various processors other than the CPU. Examples of processors in this case include FPGAs (Field-Programmable Gate Arrays) and PLDs (Programmable Logic Devices) whose circuit structures can be changed after manufacturing, and ASICs (Application Specific Integrated Circuits) as dedicated electronic circuits having processors with circuit structures specifically designed to execute specific processes. Furthermore, the aforementioned processes may 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). More specifically, the hardware structure of these various processors is an electronic circuit composed of a combination of circuit elements such as semiconductor elements.

[0114] In the above embodiment, each program is pre-stored (installed) on a computer-readable, non-temporary recording medium. For example, the control program 100 in the ECU 20 is pre-stored in the ROM 20B. However, this is not limiting. Each program may also be provided by recording it on a non-temporary recording medium such as a CD-ROM (Compact Disc Read Only Memory), a DVD-ROM (Digital Versatile Disc Read Only Memory), or a USB (Universal Serial Bus) memory device. Alternatively, the program may be downloaded from an external device via a network.

[0115] The processing flow described in the above embodiment is merely an example, and unnecessary steps may be deleted, new steps may be added, or the processing order may be changed without departing from the spirit of the invention.

Claims

1. A control device for controlling a first DC-DC converter and a second DC-DC converter for supplying power to a device, wherein: The control device comprises: a determination unit that determines whether a predetermined condition is satisfied; and a control unit that controls switching of the DCDC converter that preferentially supplies power to the device when the determination unit determines that a predetermined condition is satisfied, The control unit is composed of: When the voltage instruction value of the main DCDC converter is less than the maximum value, feedback control is performed so that the voltage instruction value of the main DCDC converter reaches the target value, and the voltage instruction value of the slave DCDC converter is controlled to a value obtained by subtracting a predetermined value from the voltage instruction value of the main DCDC converter. When the voltage instruction value of the master DCDC converter reaches a maximum value, determining whether the voltage instruction value of the slave DCDC converter is less than a value obtained by subtracting the predetermined value from the voltage instruction value of the master DCDC converter; if it is determined that the voltage instruction value of the slave DCDC converter is less than a value obtained by subtracting the predetermined value from the voltage instruction value of the master DCDC converter, feedback control is performed so that the voltage instruction value of the master DCDC converter reaches a target value, and the voltage instruction value of the slave DCDC converter is controlled to a value obtained by subtracting the predetermined value from the voltage instruction value of the master DCDC converter; if it is determined that the voltage instruction value of the slave DCDC converter is greater than or equal to the voltage instruction value of the master DCDC converter, feedback control is performed so that the voltage instruction value of the master DCDC converter reaches a maximum value, and feedback control is performed so that the voltage instruction value of the slave DCDC converter reaches the target value. When the temperature of the first DCDC converter rises and reaches a first temperature, the determination unit determines that a predetermined condition is satisfied, and the control unit switches the main DCDC converter that prioritizes power supply from the first DCDC converter to the second DCDC converter.

2. The control device according to claim 1, wherein: When the temperature of the first DCDC converter decreases and reaches a second temperature lower than the first temperature, the determination unit determines that a predetermined condition is satisfied, and the control unit switches the main DCDC converter that prioritizes power supply from the second DCDC converter to the first DCDC converter.

3. The control device according to claim 2, wherein: The second temperature is a temperature obtained by subtracting a predetermined value from a device temperature associated with the second DCDC converter.

4. The control device according to any one of claims 1 to 3, wherein: The control unit gradually increases the output power of the slave DCDC converter and then reduces the output power of the master DCDC converter to switch the DCDC converter to prioritize power supply.

5. The control device according to claim 4, wherein: When the DCDC converter giving priority to power supply is switched, after gradually increasing the voltage instruction value of the slave DCDC converter, when the voltage instruction value of the slave DCDC converter reaches the voltage instruction value of the master DCDC converter, the control unit controls the voltage instruction value of the master DCDC converter to be lower than the voltage instruction value of the slave DCDC converter.

6. A vehicle, wherein: The vehicle has: The control device according to any one of claims 1 to 5; a high-voltage battery that supplies power to each of the first DCDC converter and the second DCDC converter; and The auxiliary battery supplies electric power to the device and receives electric power from each of the first DCDC converter and the second DCDC converter.

7. A control method for controlling a first DCDC converter and a second DCDC converter for supplying power to a device, wherein: The computer performs the following processing: Determine whether the specified conditions are met, When it is determined that a predetermined condition is satisfied, control is performed to switch the DCDC converter that preferentially supplies power to the device. When the voltage instruction value of the main DCDC converter is less than the maximum value, feedback control is performed so that the voltage instruction value of the main DCDC converter reaches the target value, and the voltage instruction value of the slave DCDC converter is controlled to a value obtained by subtracting a predetermined value from the voltage instruction value of the main DCDC converter. When the voltage instruction value of the master DCDC converter reaches a maximum value, determining whether the voltage instruction value of the slave DCDC converter is less than a value obtained by subtracting the predetermined value from the voltage instruction value of the master DCDC converter; if it is determined that the voltage instruction value of the slave DCDC converter is less than a value obtained by subtracting the predetermined value from the voltage instruction value of the master DCDC converter, feedback control is performed so that the voltage instruction value of the master DCDC converter reaches a target value, and the voltage instruction value of the slave DCDC converter is controlled to a value obtained by subtracting the predetermined value from the voltage instruction value of the master DCDC converter; if it is determined that the voltage instruction value of the slave DCDC converter is greater than or equal to the voltage instruction value of the master DCDC converter, feedback control is performed so that the voltage instruction value of the master DCDC converter reaches a maximum value, and feedback control is performed so that the voltage instruction value of the slave DCDC converter reaches the target value. When the temperature of the first DCDC converter rises and reaches a first temperature, it is determined that a predetermined condition is satisfied, and a main DCDC converter prioritizing power supply is switched from the first DCDC converter to the second DCDC converter.

8. A non-transitory recording medium having a control program recorded thereon, the control program controlling a first DC-DC converter and a second DC-DC converter for supplying power to a device, wherein: The control program causes the computer to execute the following processing: Determine whether the specified conditions are met, When it is determined that a predetermined condition is satisfied, control is performed to switch the DCDC converter that preferentially supplies power to the device. When the voltage instruction value of the main DCDC converter is less than the maximum value, feedback control is performed so that the voltage instruction value of the main DCDC converter reaches the target value, and the voltage instruction value of the slave DCDC converter is controlled to a value obtained by subtracting a predetermined value from the voltage instruction value of the main DCDC converter. When the voltage instruction value of the master DCDC converter reaches a maximum value, determining whether the voltage instruction value of the slave DCDC converter is less than a value obtained by subtracting the predetermined value from the voltage instruction value of the master DCDC converter; if it is determined that the voltage instruction value of the slave DCDC converter is less than a value obtained by subtracting the predetermined value from the voltage instruction value of the master DCDC converter, feedback control is performed so that the voltage instruction value of the master DCDC converter reaches a target value, and the voltage instruction value of the slave DCDC converter is controlled to a value obtained by subtracting the predetermined value from the voltage instruction value of the master DCDC converter; if it is determined that the voltage instruction value of the slave DCDC converter is greater than or equal to the voltage instruction value of the master DCDC converter, feedback control is performed so that the voltage instruction value of the master DCDC converter reaches a maximum value, and feedback control is performed so that the voltage instruction value of the slave DCDC converter reaches the target value. When the temperature of the first DCDC converter rises and reaches a first temperature, it is determined that a predetermined condition is satisfied, and a main DCDC converter prioritizing power supply is switched from the first DCDC converter to the second DCDC converter.

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