Vehicle power supply unit
The described system accelerates capacitor precharging by initially using a resistor and then bypassing it, minimizing relay wear through controlled relay switching and current management.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Patents
- Current Assignee / Owner
- AUTONETWORKS TECH LTD
- Filing Date
- 2022-10-26
- Publication Date
- 2026-07-09
AI Technical Summary
Existing power supply systems for vehicles take too long to precharge capacitors due to limited current, which can lead to increased wear on system relays.
Incorporating a series connection of a first relay and resistor with a parallel circuit containing a second relay, allowing for capacitor precharging via the resistor initially and then bypassing it for faster precharging while minimizing relay damage.
Faster capacitor precharging is achieved while reducing damage to system relays, using a control unit to manage relay states and current thresholds for efficient switching.
Smart Images
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Abstract
Description
Technical Field
[0001] The present disclosure relates to an in-vehicle power supply device.
Background Art
[0002] Patent Document 1 discloses a power supply device for a vehicle. This power supply device includes a contactor and a precharge circuit. The contactor switches on and off the power supply from the traveling battery to the load. The precharge circuit is connected in parallel with the contactor and precharges a capacitor. The precharge circuit includes a precharge resistor that limits the precharge current and a precharge switch connected in series with this precharge resistor.
Prior Art Documents
Patent Documents
[0003]
Patent Document 1
Summary of the Invention
Problems to be Solved by the Invention
[0004] In this type of technology, when precharging the capacitor, it takes time for the capacitor voltage to reach the target voltage because the current is limited by the precharge resistor. However, depending on the situation, there may be cases where it is desired to complete the precharge of the capacitor more quickly.
[0005] The present disclosure aims to provide a technology that enables precharging through a resistance portion and can more quickly complete the precharge of the capacitor while suppressing damage to the system main relay.
Means for Solving the Problems
[0006] The in-vehicle power supply device of the present disclosure is An in-vehicle power supply device used in an in-vehicle power supply system comprising a battery, a power line supplied with power based on the battery, and a capacitor connected to the power line, A mechanical system main relay is provided in the power path on the battery side of the capacitor, The system has a configuration in which the first relay and the resistor are connected in series, and a parallel circuit is provided in parallel with the system main relay, A second relay is provided in parallel with the aforementioned resistor, It is equipped with. [Effects of the Invention]
[0007] The technology disclosed herein allows for precharging via a resistor and enables faster completion of capacitor precharging while minimizing damage to the system's main relay. [Brief explanation of the drawing]
[0008] [Figure 1] Figure 1 is a block diagram of an in-vehicle power supply system equipped with an in-vehicle power supply device according to the first embodiment. [Figure 2] Figure 2 is a flowchart showing the processing flow of the in-vehicle power supply device of the first embodiment. [Figure 3] Figure 3 is an explanatory diagram illustrating the change in capacitor voltage over time. [Modes for carrying out the invention]
[0009] The embodiments of this disclosure are listed and illustrated below.
[0010] [1] An in-vehicle power supply device used in an in-vehicle power supply system comprising a battery, a power line supplied with power based on the battery, and a capacitor connected to the power line, A mechanical system main relay is provided in the power path on the battery side of the capacitor, The system has a configuration in which the first relay and the resistor are connected in series, and a parallel circuit is provided in parallel with the system main relay, A second relay is provided in parallel with the aforementioned resistor, Equipped with Automotive power supply device.
[0011] The above-described in-vehicle power supply unit can precharge the capacitor via the resistor when the system main relay and the second relay are off and the first relay is on. Furthermore, when the system main relay is off and the first and second relays are on, the above-described in-vehicle power supply unit can precharge the capacitor more rapidly by bypassing the resistor. Therefore, the above-described in-vehicle power supply unit can precharge via the resistor and complete the precharging of the capacitor more quickly while minimizing damage to the system main relay.
[0012] [2] The system comprises a control unit that controls the system main relay, the first relay, and the second relay, The control unit, When the start condition for starting the charging and discharging of the battery is met, a first control is executed which controls the system main relay and the second relay to the off state and controls the first relay to the on state. If the first switching condition is met during the execution of the first control, the second control is executed to control the system main relay to the off state and the first relay and the second relay to the on state. If the second switching condition is met during the execution of the second control, a third control is executed which controls the first relay and the second relay to the off state and controls the system main relay to the on state. The vehicle power supply device described in [1].
[0013] The in-vehicle power supply device can switch to the second control while increasing the voltage of the capacitor to a certain extent in the first control, so as to switch to a faster pre-charge while avoiding the inflow of inrush current into the first relay. As a result, the in-vehicle power supply device can more quickly complete the pre-charge of the capacitor while suppressing damage to the system main relay.
[0014] 〔3〕The second relay is a semiconductor relay The in-vehicle power supply device according to 〔2〕.
[0015] Since the second relay of the in-vehicle power supply device is a contactless semiconductor relay, damage to the second relay can be avoided when switching from the first control to the second control.
[0016] 〔4〕The first switching condition is that the potential difference between both ends of the system main relay or the value of the current flowing through the parallel circuit becomes less than or equal to the threshold value The in-vehicle power supply device according to 〔2〕 or 〔3〕.
[0017] The in-vehicle power supply device switches to the second control after making the potential difference between both ends of the system main relay or the value of the current flowing through the parallel circuit less than or equal to the threshold value. Therefore, the in-vehicle power supply device can accurately determine the upper limit value of the current flowing through the second relay in the second control. Therefore, as a component of the second relay, it is easy for the in-vehicle power supply device to adopt a component with a rated current suitable for the second relay.
[0018] 〔5〕The first switching condition is that the first time has elapsed since the start of the first control The in-vehicle power supply device according to 〔2〕 or 〔3〕.
[0019] The above-mentioned in-vehicle power supply unit switches to the second control after one hour has elapsed from the start of the first control. In other words, the above-mentioned in-vehicle power supply unit raises the capacitor voltage to a certain extent using the first control before switching to the second control. For this reason, the above-mentioned in-vehicle power supply unit can, with a simple configuration, determine the upper limit of the current flowing to the second relay in the second control with a certain degree of accuracy. Consequently, the above-mentioned in-vehicle power supply unit can easily adopt components with a rated current suitable for the second relay as components of the second relay.
[0020] [6] The second switching condition is that a second time has elapsed, which is shorter than the first time, from the start of the second control. The vehicle-mounted power supply device described in [5].
[0021] Because the above-mentioned in-vehicle power supply unit makes it easier to secure a longer first time, it is easier to increase the capacitor voltage when switching to the second control. Therefore, the above-mentioned in-vehicle power supply unit makes it easier to use components with a low rated current as components of the second relay.
[0022] [7] The first switching condition is that the voltage of the capacitor becomes equal to or greater than the threshold voltage. The vehicle power supply device described in [2] or [3].
[0023] The above-mentioned in-vehicle power supply unit switches to the second control only after the capacitor voltage exceeds a threshold voltage. In other words, the above-mentioned in-vehicle power supply unit switches to the second control only after the difference between the battery voltage and the capacitor voltage has decreased to a certain extent. Therefore, the above-mentioned in-vehicle power supply unit can determine the upper limit of the current flowing through the second relay in the second control with a certain degree of accuracy. Consequently, the above-mentioned in-vehicle power supply unit can easily adopt components with a rated current suitable for the second relay as components of the second relay.
[0024] <First Embodiment> 1. Configuration of the in-vehicle power supply system 100 Figure 1 shows an on-board power supply system 100 equipped with an on-board power supply unit 10. The vehicle in which the on-board power supply system 100 is installed may be an electric vehicle, a fuel cell vehicle (FCV), or a hybrid vehicle. In addition to the on-board power supply unit 10, the on-board power supply system 100 includes a battery 20, a power line 21, and a capacitor 22.
[0025] Battery 20 may be a lithium-ion battery, a lead-acid battery, or any other type of battery.
[0026] The power line 21 is an electrical path through which power is supplied based on the battery 20. The power line 21 has a positive-side power line 30 and a negative-side power line 31. The positive-side power line 30 is electrically connected to the positive terminal of the battery 20. The negative-side power line 31 is electrically connected to the negative terminal of the battery 20. The negative-side power line 31 is electrically connected to ground. The output voltage of the battery 20 is applied to the power line 21 (more specifically, the positive-side power line 30). In this specification, voltage refers to the potential difference with respect to ground potential, and the potential difference with respect to the negative-side power line 31.
[0027] Capacitor 22 is electrically connected to the power line 21. Capacitor 22 is installed between the positive power line 30 and the negative power line 31. One end of capacitor 22 is electrically connected to the positive power line 30. The other end of capacitor 22 is electrically connected to the negative power line 31. Power from the battery 20 is supplied to capacitor 22 via the power line 21. Capacitor 22 smooths the voltage from the battery 20.
[0028] In this embodiment, the capacitor 22 is configured as part of a drive unit 40 provided in the in-vehicle power supply system 100. In addition to the capacitor 22, the drive unit 40 includes an inverter 41 and a motor 42. The capacitor 22 is located on the battery 20 side of the inverter 41. The capacitor 22 smooths the voltage based on the battery 20 and supplies it to the inverter 41. The inverter 41 is electrically connected to the power line 21. The inverter 41 generates an AC voltage (e.g., three-phase AC) from the DC voltage based on the voltage supplied from the battery 20 and supplies it to the motor 42. The motor 42 is, for example, a main engine motor. The motor 42 is a device that rotates based on the power supplied from the battery 20 and provides rotational force to the wheels of the vehicle.
[0029] The in-vehicle power supply unit 10 is used in the in-vehicle power supply system 100. The in-vehicle power supply unit 10 includes a first system main relay 51 (hereinafter referred to as "first SMR51") and a second system main relay 52 (hereinafter referred to as "second SMR52").
[0030] The first SMR51 corresponds to an example of a "system main relay". The first SMR51 is provided in the power line 21 on the battery 20 side of the capacitor 22. The first SMR51 is provided in the positive side power line 30. One end of the first SMR51 is electrically connected to the positive terminal of the battery 20 and short-circuits the positive terminal of the battery 20. The other end of the first SMR51 is electrically connected to one end of the capacitor 22 and short-circuits the one end of the capacitor 22. In this embodiment, the first SMR51 is a mechanical relay. The first SMR51 includes contacts 51A, 51B, and 51C. The first SMR51 includes fixed contacts 51A and 51B, a movable contact 51C, and a coil 51D that operates the movable contact 51C. When the coil 51D is energized, the first SMR51 turns on by bringing the movable contact 51C into contact with the fixed contacts 51A and 51B. Furthermore, when the coil 51D is not energized, the first SMR 51 separates the movable contact 51C from the fixed contacts 51A and 51B, resulting in an off state.
[0031] The second SMR52 is provided in the power line 21 on the battery 20 side of the capacitor 22. The second SMR52 is provided in the negative terminal power line 31. One end of the second SMR52 is electrically connected to the negative terminal of the battery 20, short-circuiting the negative terminal of the battery 20. The other end of the second SMR52 is electrically connected to the other end of the capacitor 22, short-circuiting the other end of the capacitor 22. In this embodiment, the second SMR52 is a mechanical relay. The second SMR52 includes contacts 52A, 52B, and 52C. The second SMR52 includes fixed contacts 52A and 52B, a movable contact 52C, and a coil 52D that operates the movable contact 52C. When the coil 52D is energized, the second SMR52 turns on by bringing the movable contact 52C into contact with the fixed contacts 52A and 52B. Furthermore, when the coil 52D is not energized, the second SMR 52 separates the movable contact 52C from the fixed contacts 52A and 52B, resulting in an off state.
[0032] The positive electrode power line 30 described above includes a first positive electrode power line 32 provided on the battery 20 side relative to the first SMR 51, and a second positive electrode power line 33 provided on the side opposite to the battery 20 relative to the first SMR 51. The negative electrode power line 31 described above includes a first negative electrode power line 34 provided on the battery 20 side relative to the second SMR 52, and a second negative electrode power line 35 provided on the side opposite to the battery 20 relative to the second SMR 52.
[0033] The vehicle power supply unit 10 includes a parallel circuit 53. The parallel circuit 53 is provided in parallel with the first SMR 51. One end of the parallel circuit 53 is electrically connected to the first positive power line 32 and short-circuits the first positive power line 32. The other end of the parallel circuit 53 is electrically connected to the second positive power line 33 and short-circuits the second positive power line 33. The parallel circuit 53 has a configuration in which the first relay 54 and the resistor 55 are connected in series.
[0034] In this embodiment, the first relay 54 is a mechanical relay. The first relay 54 includes contacts 54A, 54B, and 54C. The first relay 54 includes fixed contacts 54A and 54B, a movable contact 54C, and a coil 54D that operates the movable contact 54C. When the coil 54D is energized, the first relay 54 turns on by bringing the movable contact 54C into contact with the fixed contacts 54A and 54B. Conversely, when the coil 54D is not energized, the first relay 54 turns off by separating the movable contact 54C from the fixed contacts 54A and 54B.
[0035] The resistive section 55 is composed of, for example, a well-known resistor.
[0036] The in-vehicle power supply unit 10 includes a second relay 56. The second relay 56 is provided in parallel with the resistor 55. In this embodiment, the second relay 56 is a semiconductor relay. In this embodiment, the second relay 56 is an N-channel MOSFET (Metal-Oxide-Semiconductor Field Effect Transistor). The second relay 56 has an input section 56A (gate in this embodiment). The second relay 56 turns on when an ON signal (high-level signal in this embodiment) is applied to the input section 56A, and turns off when an OFF signal (low-level signal in this embodiment) is applied to the input section 56A. The drain 56B of the second relay 56 is electrically connected to the end of the resistor 55 on the first positive power line 32 side, and short-circuits the end of the resistor 55 on the first positive power line 32 side. The source 56C of the second relay 56 is electrically connected to the end of the resistor 55 on the second positive power line 33 side, and short-circuits the end of the resistor 55 on the second positive power line 33 side.
[0037] 2. Configuration of the control unit 57 of the in-vehicle power supply unit 10 The in-vehicle power supply unit 10 includes a control unit 57. The control unit 57 is configured to include, for example, a control circuit such as an integrated circuit. The control unit 57 includes a processing unit such as a CPU, a storage unit such as memory, an input / output unit, and so on. The control unit 57 controls the first SMR 51, the second SMR 52, the first relay 54, and the second relay 56.
[0038] The control unit 57 executes a first control when the start condition for starting the charging and discharging of the battery 20 is met. The start condition is met when the first SMR 51, second SMR 52, first relay 54, and second relay 56 are in the off state. The first control is a control that controls the first SMR 51 and second relay 56 to the off state, and controls the second SMR 52 and first relay 54 to the on state. Alternatively, the first control is a control that switches the second SMR 52 and first relay 54 to the on state while keeping the first SMR 51 and second relay 56 in the off state. When the first control is performed, power from the battery 20 is supplied to the capacitor 22 via the parallel circuit 53. With this configuration, the current flowing through the power path 21 is suppressed by the resistance 55 of the parallel circuit 53. Therefore, the capacitor 22 can be charged while suppressing damage to the first SMR 51, second SMR 52, and first relay 54. As the voltage across capacitor 22 increases, the difference between the voltage across capacitor 22 and the voltage across battery 20 decreases. As a result, the potential difference across the first SMR 51 decreases, and the potential difference across the second SMR 52 decreases.
[0039] The control unit 57 executes the second control if the first switching condition is met during the execution of the first control. The second control controls the first SMR 51 to the off state and controls the second SMR 52, the first relay 54, and the second relay 56 to the on state. Alternatively, the second control maintains the first SMR 51 in the off state and switches the second relay 56 to the on state while maintaining the second SMR 52 and the first relay 54 in the on state.
[0040] The first switching condition is, for example, a condition that is met when the current flowing through the parallel circuit 53 is less than or equal to the rated current of the second relay 56. The first switching condition is, for example, a condition that is set to be met when the current flowing through the parallel circuit 53 becomes less than or equal to the rated current of the second relay 56.
[0041] A first example of the first switching condition is that the potential difference across the first SMR51 falls below a first threshold. The control unit 57 acquires the potential difference across the first SMR51 and determines whether the acquired potential difference is below the first threshold. The method by which the control unit 57 acquires the potential difference across the first SMR51 is not limited. For example, the control unit 57 may acquire the potential difference across the first SMR51 by receiving a signal amplified by a differential amplifier. Alternatively, the control unit 57 may acquire the voltage of the battery 20 and the voltage of the capacitor 22 separately and acquire the potential difference across the first SMR51 by calculating the difference between them. When the first switching condition is the first example, the on-board power supply unit 10 switches to the second control after reducing the potential difference across the first SMR 51 to below the first threshold. Therefore, the on-board power supply unit 10 can accurately determine the upper limit of the current flowing through the second relay 56 in the second control. Consequently, the on-board power supply unit 10 can easily adopt components with a rated current suitable for the second relay 56 as components of the second relay 56.
[0042] A second example of the first switching condition is that the value of the current flowing through the parallel circuit 53 falls below the first threshold. The control unit 57 acquires the value of the current flowing through the parallel circuit 53 and determines whether the acquired value of the current has fallen below the first threshold. The method by which the control unit 57 acquires the value of the current flowing through the parallel circuit 53 is not limited. For example, the in-vehicle power supply system 100 may be equipped with a current sensor that detects the current flowing through the parallel circuit 53, and the control unit 57 may acquire the value detected by the current sensor. When the first switching condition is the second example, the in-vehicle power supply unit 10 switches to the second control after reducing the value of the current flowing through the parallel circuit 53 to below the first threshold. Therefore, the in-vehicle power supply unit 10 can accurately determine the upper limit of the current flowing through the second relay 56 in the second control. Consequently, the in-vehicle power supply unit 10 can easily adopt components with a rated current suitable for the second relay 56 as components of the second relay 56.
[0043] A third example of the first switching condition is that one hour has elapsed since the start of the first control. If the first switching condition is the third example, the on-board power supply unit 10 switches to the second control after 1 hour has elapsed from the start of the first control. In other words, the on-board power supply unit 10 raises the voltage of the capacitor 22 to a certain extent by the first control before switching to the second control. For this reason, the on-board power supply unit 10 can determine the upper limit of the current flowing through the second relay 56 in the second control with a certain degree of accuracy using a simple configuration. Therefore, the on-board power supply unit 10 can easily adopt components with a rated current suitable for the second relay 56 as components of the second relay 56.
[0044] A fourth example of the first switching condition is that the voltage across capacitor 22 becomes equal to or greater than the first threshold voltage. The control unit 57 acquires the voltage across capacitor 22 and determines whether the acquired voltage is equal to or greater than the first threshold voltage. The method by which the control unit 57 acquires the voltage across capacitor 22 is not limited. For example, the control unit 57 may acquire the voltage across capacitor 22 detected by a known voltage detection circuit. When the first switching condition is the fourth example, the on-board power supply unit 10 switches to the second control only after the voltage of the capacitor 22 becomes equal to or greater than the first threshold voltage. In other words, the on-board power supply unit 10 switches to the second control only after the difference between the voltage of the battery 20 and the voltage of the capacitor 22 has decreased to a certain extent. Therefore, the on-board power supply unit 10 can determine the upper limit of the current flowing through the second relay 56 with a certain degree of accuracy in the second control. Consequently, the on-board power supply unit 10 can easily adopt components with a rated current suitable for the second relay 56 as components of the second relay 56.
[0045] The control unit 57 executes the third control if the second switching condition is met while the second control is being executed. The third control controls the first relay 54 and the second relay 56 to the off state and the first SMR 51 and the second SMR 52 to the on state. Alternatively, the third control keeps the second SMR 52 on while switching the first relay 54 and the second relay 56 to the off state and switching the first SMR 51 to the on state.
[0046] The second switching condition is, for example, a condition that is met when the potential difference across the first SMR51 is less than or equal to a target value. The second switching condition is, for example, a condition set to be met when the potential difference across the first SMR51 becomes less than or equal to a target value. The target value is, for example, 0.
[0047] A first example of the second switching condition is that the potential difference across the first SMR51 falls below the second threshold. The second threshold is smaller than the first threshold when the first switching condition is the first example. The control unit 57 acquires the potential difference across the first SMR51 and determines whether the acquired potential difference is below the second threshold. The method by which the control unit 57 acquires the potential difference across the first SMR51 is not limited and may be the same as, for example, the first example of the first switching condition. When the second switching condition is the first example, the on-board power supply unit 10 reduces the potential difference across the first SMR51 to below the second threshold before switching to the third control. As a result, the on-board power supply unit 10 can more reliably suppress the inrush current flowing through the first SMR51.
[0048] A second example of the second switching condition is that the value of the current flowing through the parallel circuit 53 falls below the second threshold. The second threshold is smaller than the first threshold when the first switching condition is the second example. The control unit 57 obtains the value of the current flowing through the parallel circuit 53 and determines whether the obtained current value is below the second threshold. The method by which the control unit 57 obtains the value of the current flowing through the parallel circuit 53 is not limited and may be the same as, for example, the second example of the first switching condition. When the second switching condition is the second example, the on-board power supply unit 10 reduces the value of the current flowing through the parallel circuit 53 to below the second threshold before switching to the third control. As a result, the on-board power supply unit 10 can more reliably suppress the inrush current flowing through the first SMR 51.
[0049] A third example of the second switching condition is that two hours have elapsed since the start of the second control. The second hour is shorter than the first hour, for example, when the first switching condition is the third example. In this case, the on-board power supply unit 10 can easily ensure a longer first hour, and therefore can easily increase the voltage of the capacitor 22 when switching to the second control. Consequently, the on-board power supply unit 10 can easily use components with a low rated current as components of the second relay 56. If the second switching condition is the third example, the in-vehicle power supply unit 10 can easily simplify the determination of whether or not the second switching condition has been met.
[0050] A fourth example of the second switching condition is that the voltage across capacitor 22 becomes equal to or greater than the second threshold voltage. The second threshold voltage is greater than the first threshold voltage when the first switching condition is the fourth example. The control unit 57 obtains the voltage across capacitor 22 and determines whether the obtained voltage is equal to or greater than the first threshold. The method by which the control unit 57 obtains the voltage across capacitor 22 is not limited and may be the same as, for example, the same as the fourth example of the first switching condition. When the second switching condition is the fourth example, the in-vehicle power supply unit 10 can switch the first SMR 51 to the ON state after reducing the potential difference between the voltage of the capacitor 22 and the voltage of the battery 20 to a certain extent, without monitoring the potential difference. Therefore, the in-vehicle power supply unit 10 can suppress damage to the first SMR 51 associated with switching to the ON state to a certain extent with a simple configuration.
[0051] 3. Operation of the vehicle power supply unit 10 The control unit 57 of the in-vehicle power supply unit 10 performs the processing shown in Figure 2. The control unit 57 starts the processing shown in Figure 2, for example, when the first SMR 51, the second SMR 52, the first relay 54, and the second relay 56 are in the off state.
[0052] In step S101, the control unit 57 determines whether the above-described start condition has been met. For example, the control unit 57 determines that the start condition has been met when it receives an instruction to start charging and discharging from the higher-level ECU. If the control unit 57 determines that the start condition has not been met (the result is No in step S101), it repeats the process in step S101 until the start condition is met.
[0053] If the control unit 57 determines that the start condition has been met (Yes in step S101), it starts the first control in step S102. That is, the control unit 57 keeps the first SMR 51 and the second relay 56 in the off state and switches the second SMR 52 and the first relay 54 to the on state. As a result, power from the battery 20 is charged to the capacitor 22 via the parallel circuit 53. In other words, the current limited by the resistor 55 flows through the power path 21 and charges the capacitor 22.
[0054] The control unit 57 performs the process in step S103 while the first control is being executed. In step S103, the control unit 57 determines whether the first switching condition described above has been met. If the control unit 57 determines that the first switching condition has not been met (No in step S103), it repeats the process in step S103 until the first switching condition is met. During this time, the voltage across the capacitor 22 gradually increases, and the potential difference across the first SMR 51 gradually decreases.
[0055] If the control unit 57 determines that the first switching condition is met (Yes in step S103), it switches to the second control in step S104. That is, the control unit 57 keeps the first SMR 51 in the off state and the second SMR 52 in the on state, and switches the second relay 56 to the on state. As a result, the power from the battery 20 is charged to the capacitor 22 by bypassing the resistor 55. In other words, the current from the battery 20 is supplied to the capacitor 22 without being limited by the resistor 55.
[0056] The control unit 57 performs the process in step S105 while the second control is being executed. In step S105, the control unit 57 determines whether the second switching condition described above has been met. If the control unit 57 determines that the second switching condition has not been met (if the result in step S105 is No), it repeats the process in step S105 until the second switching condition is met. During this time, the voltage across capacitor 22 rises further, and the potential difference across the first SMR 51 becomes even smaller.
[0057] If the control unit 57 determines that the second switching condition is met (Yes in step S105), it switches to the third control in step S106. That is, the control unit 57 keeps the second SMR 52 in the ON state, switches the first relay 54 and the second relay 56 to the OFF state, and switches the first SMR 51 to the ON state. By switching the first SMR 51 to the ON state when the potential difference across the first SMR 51 is reduced, damage to the first SMR 51 is suppressed. When the third control is executed, power based on the battery 20 is supplied to the power line 21 via the first SMR 51, and then supplied to the drive unit 40 via the power line 21.
[0058] After switching to the third control, the control unit 57 terminates the process shown in Figure 2.
[0059] Figure 3 shows the change in the voltage of capacitor 22 over time, indicated by a solid line. When the starting conditions are met and the first control is disclosed, the voltage of capacitor 22 gradually rises from 0V. The rate at which the voltage of capacitor 22 rises slows down as the voltage of capacitor 22 approaches the voltage of battery 20. At timing t1, when the rate at which the voltage of capacitor 22 rises slows down, the control unit 57 switches to the second control. This accelerates the rate at which the voltage of capacitor 22 rises, and at timing t2, the voltage of capacitor 22 reaches the target voltage. If the control unit 57 did not switch to the second control at timing t1, it would take a considerable amount of time for the voltage of capacitor 22 to reach the target voltage, as shown by the dashed curve. In contrast, the in-vehicle power supply unit 10 can significantly reduce the time required for the voltage of capacitor 22 to reach the target voltage by switching to the second control at timing t1.
[0060] 4. Examples of effects The in-vehicle power supply unit 10 can precharge the capacitor 22 via the resistor 55 when the first SMR 51 and the second relay 56 are off and the first relay 54 is on. Furthermore, the in-vehicle power supply unit 10 can precharge the capacitor 22 more rapidly by bypassing the resistor 55 when the first SMR 51 is off and the first relay 54 and the second relay 56 are on. Therefore, the in-vehicle power supply unit 10 can precharge via the resistor 55 and complete the precharging of the capacitor 22 more quickly while minimizing damage to the first SMR 51.
[0061] The in-vehicle power supply unit 10 can switch to a more rapid pre-charge mode while avoiding an inrush current flowing through the first relay 54 by switching to the second control mode after raising the voltage of the capacitor 22 to a certain level in the first control mode. As a result, the in-vehicle power supply unit 10 can complete the pre-charge of the capacitor 22 more quickly while minimizing damage to the first SMR 51.
[0062] Since the in-vehicle power supply unit 10 has a second relay 56 that is a contactless semiconductor relay, damage to the second relay 56 can be avoided when switching from the first control to the second control.
[0063] <Other Embodiments> This disclosure is not limited to the embodiments described above and in the drawings. For example, any combination of the features of the embodiments described above or below is possible as long as it does not contradict each other. Furthermore, any feature of the embodiments described above or below may be omitted unless explicitly stated as essential. In addition, the embodiments described above may be modified as follows.
[0064] In each of the above embodiments, the second SMR52 may not be provided.
[0065] In the embodiments described above, the first SMR51 was configured to be an example of a system main relay, but the second SMR52 may also be an example of a system main relay. In this case, the parallel circuit 53 is provided in parallel with the second SMR52. In this case, the first SMR51 may not be provided.
[0066] In the above embodiments, the first relay 54 was a mechanical relay, but it may also be a semiconductor relay. In the above embodiments, the second relay 56 was a semiconductor relay, but it may also be a mechanical relay.
[0067] It should be noted that the embodiments disclosed herein are illustrative and not restrictive in all respects. The scope of the present invention is not limited to the embodiments disclosed herein, and is intended to include all modifications within the scope set forth in the claims or within the scope equivalent to the claims. [Explanation of Symbols]
[0068] 10…Vehicle power supply unit 20… Battery 21…Power line 22…Capacitor 30…Positive side power line 31... Negative side power line 32…First positive terminal power line 33…Second positive electrode power line 34…First negative electrode power line 35...Second negative electrode power line 40…Drive unit 41…Inverter 42…motor 51…First system main relay (system main relay) 51A…Contact, fixed contact 51B…Contact, fixed contact 51C…Contact, movable contact 51D... Coil 52…Second system main relay 52A... Contact, fixed contact 52B... Contact, fixed contact 52C…Contact, movable contact 52D... Coil 53...Parallel circuit 54…1st Relay 54A... Contact, fixed contact 54B... Contact, fixed contact 54C…Contact, movable contact 54D... Coil 55...Resistance part 56…2nd Relay 56A...Input section 56B...Drain 56C... Source 57…Control Unit 100... Vehicle-mounted power supply system
Claims
1. An in-vehicle power supply device used in an in-vehicle power supply system comprising a battery, a power line supplied with power based on the battery, and a capacitor connected to the power line, A mechanical system main relay is provided in the power path on the battery side of the capacitor, The system has a configuration in which the first relay and the resistor are connected in series, and a parallel circuit is provided in parallel with the system main relay, A second relay is provided in parallel with the aforementioned resistor, The system comprises a control unit that controls the system main relay, the first relay, and the second relay, The control unit, When the start condition for starting the charging and discharging of the battery is met, a first control is executed which controls the system main relay and the second relay to the off state and controls the first relay to the on state. If the first switching condition is met during the execution of the first control, the second control is executed to control the system main relay to the off state and the first relay and the second relay to the on state. If the second switching condition is met during the execution of the second control, a third control is executed which controls the first relay and the second relay to the off state and controls the system main relay to the on state. The first switching condition is that a first time has elapsed since the start of the first control. The second switching condition is that a second time has elapsed, which is shorter than the first time, from the start of the second control. Automotive power supply device.
2. The second relay is a semiconductor relay. The in-vehicle power supply device according to claim 1.