Charging system, charger and charging system control method

Abstract

The charging system (11) includes: a main battery (4) that stores power for vehicle travel; an inlet (1) that is connected to a charging connector (910); a charging relay (31) that switches the path of power from the inlet to the main battery; a converter (25) that steps down the voltage of the power from the inlet; and an ECU (10) that controls the charging relay and the converter. The ECU: controls the converter so that the converter starts to step down the voltage of the power from the inlet to an auxiliary voltage after receiving power from the inlet (steps S114, S124); supplies the power from the converter to the charging relay as operating power for switching to the connected state before the charging relay switches to the connected state (steps S114, S124); and controls the charging relay so that the charging relay switches from the disconnected state to the connected state using the operating power (steps S117, S127).

Description

Technical Field

[0001] The present disclosure relates to a charging system, a charger, a charging system control method, and more particularly, to: a charging system including a charging relay for switching a power path from an inlet to a main battery between a connected state and a disconnected state; a charger connected to the charging relay; and a method for controlling the charging system. Background Art

[0002] An electric vehicle generally includes a main direct-current (DC)-to-DC converter, which is used to step down the power of the main battery of the high-voltage system to drive the vehicle and supply the power to the auxiliary system (see, for example, Japanese Patent Publication No. 2020-072591). It is conventionally known that, in view of the improvement in efficiency, a sub-DC-DC converter different from the main DC-DC converter is used to supply power to the auxiliary system during external charging of the main battery. The sub-DC-DC converter is a DC-DC converter that is separately provided from the main DC-DC converter in the charger. The sub-DC-DC converter converts power from an external power supply for supply to the auxiliary system.

[0003] The circuit for external charging of electric vehicles generally includes a charging relay capable of switching an electrical connection state and an electrical disconnection state between a charger and a main battery. The charging relay operates using power supplied from an auxiliary system. Conventionally, before external charging begins, the charging relay operates using power stored in an auxiliary battery. Summary of the invention

[0004] Whenever the main battery is externally charged, the charging relay switches from the disconnected state to the connected state at least once. The more times the charging relay performs the switching operation, the higher the minimum required operating voltage for the switching operation. At the same time, the voltage supplied by the auxiliary battery may decrease depending on the state of charge (SOC) of the auxiliary battery when power is supplied and the aging of the auxiliary battery. There is a concern that if the voltage supplied by the auxiliary battery is insufficient as the operating voltage of the charging relay, the charging relay may not be switched to the connected state before the start of external charging.

[0005] The present disclosure is made to solve the above-mentioned problem, and an object of the present disclosure is to provide a charging system, a charger, and a control method of the charging system that can prevent a charging relay from failing to switch to a connection state before external charging starts.

[0006] The charging system according to the present disclosure includes: a main battery that stores power for vehicle travel; an inlet that is connected to a charging connector for supplying power to charge the main battery; a charging relay that switches the path of power from the inlet to the main battery between a connected state and a disconnected state; an inlet-side voltage converter that steps down the voltage of the power from the inlet to an auxiliary voltage; and a controller that controls the charging relay and the inlet-side voltage converter. The controller: controls the inlet-side voltage converter so that the inlet-side voltage converter starts to step down the voltage of the power from the inlet to the auxiliary voltage after receiving power from the inlet; supplies the power from the inlet-side voltage converter to the charging relay as an operating power for switching to the connected state before the charging relay switches to the connected state; and controls the charging relay so that the charging relay switches from the disconnected state to the connected state using the operating power.

[0007] According to such a configuration, after power is supplied to the vehicle from the external power via the inlet and before external charging starts, the inlet-side voltage converter starts to step down the voltage to the auxiliary voltage; the charging relay is supplied with power from the inlet-side voltage converter as operating power for switching to the connected state before switching to the connected state; and the charging relay switches from the disconnected state to the connected state using the operating power. As a result, a charging system can be provided that can prevent the charging relay from failing to switch to the connected state before external charging starts.

[0008] The charging system may further include: an auxiliary battery storing power having the auxiliary voltage, wherein the inlet-side voltage converter may be connected in parallel to the auxiliary battery.

[0009] The charging system may further include a main battery side power converter which is different from the inlet side voltage converter and steps down the voltage of the power of the main battery to the auxiliary voltage to supply the power stored in the main battery to the auxiliary battery.

[0010] The controller may control the inlet-side voltage converter so that the inlet-side voltage converter is actuated to supply the operating power to the charging relay regardless of a voltage of the auxiliary battery.

[0011] The charging system may further include a voltage sensor that senses the voltage of the auxiliary battery, wherein, when the voltage sensed by the voltage sensor is less than a predetermined voltage, the controller may control the inlet side voltage converter so that the inlet side voltage converter is actuated to supply the operating power to the charging relay.

[0012] After the inlet-side voltage converter is activated, when the voltage sensed by the voltage sensor is greater than or equal to the predetermined voltage, the controller may supply the operating power to the charging relay.

[0013] The controller may supply the operating power to the charging relay after a predetermined period of time has elapsed from activation of the inlet-side voltage converter.

[0014] According to another aspect of the present disclosure, a charger includes: a power supply unit that supplies power from an inlet connected to a charging connector for supplying power to charge a main battery storing power for vehicle travel to a charging relay, the charging relay switching a path of power to the main battery between a connected state and a disconnected state; and an inlet-side voltage converter that steps down a voltage of power from the inlet to an auxiliary voltage. After receiving power from the inlet, the inlet-side voltage converter steps down a voltage of power from the inlet to the auxiliary voltage so that the power from the inlet is supplied to the charging relay as an operating power for switching to the connected state before the charging relay switches to the connected state.

[0015] According to such a configuration, it is possible to provide a charger capable of preventing the charging relay from failing to switch to the connection state before external charging starts.

[0016] According to another aspect of the present disclosure, in a method for controlling a charging system, the charging system includes: a main battery that stores power for vehicle travel; an inlet that is connected to a charging connector for supplying power to charge the main battery; a charging relay that switches a path of power from the inlet to the main battery between a connected state and a disconnected state; an inlet-side voltage converter that steps down a voltage of power from the inlet to an auxiliary voltage; and a controller that controls the charging relay and the inlet-side voltage converter. The method includes: controlling the inlet-side voltage converter by the controller so that the inlet-side voltage converter starts to step down a voltage of power from the inlet to the auxiliary voltage after receiving power from the inlet; supplying power from the inlet-side voltage converter to the charging relay as an operating power for switching to the connected state before the charging relay switches to the connected state; and controlling the charging relay so that the charging relay switches from the disconnected state to the connected state using the operating power.

[0017] According to such a configuration, it is possible to provide a charging system control method capable of preventing the charging relay from failing to switch to the connection state before external charging starts.

[0018] The foregoing and other objects, features, aspects and advantages of the present disclosure will become more apparent from the following detailed description of the present disclosure when taken in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 is a block diagram schematically showing the overall configuration of a vehicle according to the embodiment.

[0020] Figure 2 : is a flowchart showing the flow of the battery charging start process according to the first embodiment.

[0021] Figure 3 is a graph of operating voltages of a charging relay according to an embodiment.

[0022] Figure 4 : is a flowchart showing the flow of battery charging start processing according to the second embodiment. DETAILED DESCRIPTION

[0023] [Example 1]

[0024] Hereinafter, embodiments according to the present disclosure will be described with reference to the accompanying drawings. In the following description, similar reference numerals refer to similar components. Their names and functions are also the same. Therefore, their detailed description will not be repeated.

[0025] Figure 1 is a block diagram schematically showing the overall configuration of the vehicle 100 according to the present embodiment. Figure 1 , the vehicle 100 can be externally charged using power supplied from the external device 900. In this example, the vehicle 100 is a pure electric vehicle (battery electric vehicle). However, the vehicle 100 may be a plug-in hybrid electric vehicle or a fuel cell electric vehicle, etc.

[0026] The vehicle 100 includes a charging system 11, a system main relay (System Main Relay, SMR) 32, a high voltage load 51, an auxiliary load 52, a power control unit (Power Control Unit, PCU) 8, a motor generator 9, and an electronic control unit (Electronic Control Unit, ECU) 10. The charging system 11 includes an inlet 1, a charger 2, a charging relay 31, a main battery 4, a voltage sensor 41, a current sensor 42, an auxiliary battery 6, a voltage sensor 61, a current sensor 62, a main DC-DC converter 7, a sub DC-DC converter 25, and an electronic control unit (ECU) 10.

[0027] The inlet 1 is connected to a charging connector 910 provided at the end of a charging cable. The inlet 1 receives alternating-current (AC) power supplied from an external device 900 such as a charging station via the charging connector 910. The AC power received by the inlet 1 is transmitted to the charger 2.

[0028] The charger 2 includes a filter circuit 21 , a power factor correction (PFC) circuit 22 , smoothing capacitors 23 and 28 , a high-voltage DC-DC converter 24 , a sub-DC-DC converter 25 , and voltage sensors 26 and 27 .

[0029] The filter circuit 21 removes noise from the AC power transmitted from the inlet 1, and outputs the AC power from which the noise is removed to the PFC circuit 22. The voltage sensor 26 detects the voltage at the input of the charger 2, that is, the voltage to be input to the filter circuit 21, and outputs the detection result to the ECU 10.

[0030] The PFC circuit 22 is controlled by the ECU 10, rectifies, boosts, and then outputs the AC power from which noise is removed by the filter circuit 21 to the smoothing capacitor 23, while making the input current close to a sine, thereby improving the power factor. As is well known, the PFC circuit 22 can adopt various types of PFC circuits. Note that, instead of the PFC circuit 22, a rectifier without a power factor improvement function may be adopted.

[0031] The smoothing capacitor 23 smoothes the voltage variation of the DC power received from the PFC circuit 22. The smoothed DC power is supplied to the high-voltage DC-DC converter 24 and the sub-DC-DC converter 25. The voltage sensor 27 detects the voltage across the smoothing capacitor 23, that is, the voltage to be supplied to the high-voltage DC-DC converter 24 and the sub-DC-DC converter 25, and outputs the result detection to the ECU 10.

[0032] The high-voltage DC-DC converter 24 is controlled by the ECU 10 to convert the voltage of the DC power that has been smoothed by the smoothing capacitor 23 into a voltage suitable for charging the main battery 4 (for example, higher than 200 V).

[0033] The smoothing capacitor 28 smoothes voltage variations of the DC power received from the high-voltage DC-DC converter 24 .

[0034] The sub DC-DC converter 25 is controlled by the ECU 10 to convert the voltage of the DC power smoothed by the smoothing capacitor 23 into a voltage (for example, 14 V) suitable for charging the auxiliary battery 6 .

[0035] The charging relay 31 is electrically connected between the high-voltage DC-DC converter 24 and the main battery 4. During external charging, the charging relay 31 is basically closed in accordance with the control command from the ECU 10. The closed state of the relay will be referred to as the connected state, and the open state of the relay will be referred to as the disconnected state. This enables the main battery 4 to be supplied with power from the charger 2.

[0036] The system main relay 32 is electrically connected between the main battery 4 and the high-voltage load 51 and between the main battery 4 and the PCU 8. While the vehicle 100 is running, the system main relay 32 is closed according to a control command from the ECU 10. Thus, power is supplied from the main battery 4 to the high-voltage load 51 and the PCU 8, so that the motor generator 9 can be driven.

[0037] The main battery 4 is electrically connected between the charging relay 31 and the system main relay 32. The main battery 4 is an assembled battery formed of a plurality of unit cells. Each unit cell is a secondary battery such as a lithium-ion battery or a nickel-hydrogen battery. The main battery 4 has a high output voltage of, for example, about 200 V. The main battery 4 supplies power for generating a driving force of the vehicle 100. The main battery 4 also stores power obtained by power regeneration of the motor generator 9.

[0038] The voltage sensor 41 detects the voltage of the main battery 4 and outputs the detection result to the ECU 10. The current sensor 42 detects the current input / output to / from the main battery 4 and outputs the detection result to the ECU 10. Based on the detection results output from the voltage sensor 41 and the current sensor 42, the ECU 10 can calculate the state of charge (SOC) of the main battery 4.

[0039] The high voltage load 51 is electrically connected to the main battery 4 via the system main relay 32, and is electrically connected to the main DC-DC converter 7. For example, the high voltage load 51 may include an air conditioner, a seat heater, and an inverter for a socket provided inside the vehicle.

[0040] The auxiliary loads 52 are electrically connected to the auxiliary battery 6. For example, the auxiliary loads 52 may include lights (headlights, fog lights, turn signals, cornering lights, etc.), audio equipment, a car navigation system, an anti-lock brake system (ABS), an oil pump, an instrument, a defogger, and a windshield wiper.

[0041] The auxiliary battery 6 is electrically connected between the sub-DC-DC converter 25 and the main DC-DC converter 7. The auxiliary battery 6 is a lithium-ion battery such as a lead battery or a rechargeable battery. The auxiliary battery 6 has a lower output voltage than the main battery 4, for example, about 12V.

[0042] The voltage sensor 61 detects the voltage of the auxiliary battery 6 and outputs the detection result to the ECU 10. The current sensor 62 detects the current input / output to / from the auxiliary battery 6 and outputs the detection result to the ECU 10. Based on the detection results by the voltage sensor 61 and the current sensor 62, the ECU 10 can calculate the SOC of the auxiliary battery 6.

[0043] The main DC-DC converter 7 is electrically connected between the auxiliary battery 6 and the main battery 4 via the system main relay 32. The main DC-DC converter 7 converts the voltage of the power from the main battery 4 and supplies the converted voltage of the power to the auxiliary battery 6. The main DC-DC converter 7 has a larger power capacity (capability of supplying current to a load) than the sub-DC-DC converter 25.

[0044] According to control commands from the ECU 10, the PCU 8 converts power between the main battery 4 and the motor generator 9. The PCU 8 may include an inverter for driving the motor generator 9 with power supplied from the main battery 4 and a converter for adjusting the level of a DC voltage supplied to the inverter, both of which are not shown.

[0045] The motor generator 9 is an AC rotary electric machine, for example, a permanent magnet synchronous motor including a rotor having a permanent magnet embedded therein. The output torque of the motor generator 9 is transmitted to the drive wheels via a mechanical power transmission gear composed of a speed reducer and a power distribution device (neither of which are shown in the figure), so that the vehicle 100 travels. When the vehicle 100 is regeneratively braked, the motor generator 9 can generate electric power by the rotational force of the drive wheels. The electric power thus generated is converted by the PCU 8 into electric power for charging the main battery 4.

[0046] The ECU 10 includes a processor such as a central processing unit (CPU), a memory such as a read-only memory (ROM) and a random access memory (RAM), and an input / output port, all of which are not shown. The ECU 10 controls and monitors each device included in the vehicle 100 based on signals received from the above-mentioned sensors and programs and maps stored in the memory. Figure 1 An exemplary configuration is shown in which all devices included in the vehicle 100 are controlled by the ECU 10, but it should be noted that the ECU 10 may be divided into a plurality of ECUs according to functions. Various controls performed by the ECU 10 are not limited to processing by software, and they may be constructed in dedicated hardware (circuit) and processed.

[0047] Conventionally, before external charging starts, the charging relay 31 is operated using the power stored in the auxiliary battery 6. Whenever the main battery 4 is externally charged, the charging relay 31 is switched from the disconnected state to the connected state at least once. The more times the charging relay 31 performs the switching operation, the higher the minimum required operating voltage for the switching operation. Meanwhile, the voltage supplied by the auxiliary battery 6 may decrease depending on the SOC when the power is supplied and the aging of the auxiliary battery 6. There is a concern that if the voltage supplied by the auxiliary battery 6 is insufficient as the operating voltage of the charging relay 31, the charging relay 31 may not be switched to the connected state before the external charging starts.

[0048] Therefore, the ECU 10: controls the sub-DC-DC converter 25 so that the sub-DC-DC converter 25 starts to step down the voltage to a voltage suitable for charging the auxiliary battery after receiving power from the inlet 1; supplies the power output from the sub-DC-DC converter 25 to the charging relay 31 as the operating power for switching the charging relay 31 to the connected state before the charging relay 31 switches to the connected state; and controls the charging relay 31 so that the charging relay 31 uses the operating power to switch from the disconnected state to the connected state.

[0049] This allows: after power is supplied to the vehicle 100 from the external power via the inlet 1 and before external charging starts, the sub-DC-DC converter 25 starts to step down the voltage to a voltage suitable for charging the auxiliary battery 6; the charging relay 31 is supplied with power from the sub-DC-DC converter 25 as operating power for switching to the connected state before switching to the connected state; and the charging relay 31 switches from the disconnected state to the connected state using the operating power. As a result, it is possible to prevent the charging relay 31 from failing to switch to the connected state before external charging starts.

[0050] Figure 2 : is a flowchart showing the flow of the battery charging start process according to the first embodiment. Figure 2 , the battery charging start process is called from the upper layer process at predetermined intervals and executed. The CPU included in the ECU 10 determines whether the sub DC-DC converter 25 is not activated (step S111).

[0051] If it is determined that the sub-DC-DC converter 25 is not activated ("Yes" in step S111), the CPU included in the ECU 10 uses the result of detection by the voltage sensor 61 to determine whether the voltage of the auxiliary battery 6 is less than a predetermined voltage (step S112). The predetermined voltage is at least greater than or equal to the voltage required for the charging relay 31 to switch from the disconnected state to the connected state (hereinafter, referred to as "on voltage"), for example, the voltage described below. Figure 3 The voltage Va shown in .

[0052] Figure 3 is a graph of the operating voltage of the charging relay 31 according to the present embodiment. Figure 3 , the number of operations of the charging relay 31 is represented on the horizontal axis, and the on-voltage of the charging relay 31 is represented on the vertical axis. The curve points show the transition of the on-voltage in response to the number of operations of the charging relay 31. As represented by the line of the graph connecting the curve points, as the number of operations of the charging relay 31 increases, the on-voltage tends to increase.

[0053] If the voltage Vb is supplied to the charging relay 31, the supply voltage Vb at the third curve point from the left is greater than the conduction voltage in response to the number of operations of the charging relay 31. Therefore, the charging relay 31 can be switched from the disconnected state to the connected state. In contrast, the supply voltage Vb at the fourth curve point from the left is less than the conduction voltage in response to the number of operations of the charging relay 31. Therefore, the charging relay 31 cannot be switched from the disconnected state to the connected state.

[0054] If the supply voltage is the voltage Va, the supply voltage Va is greater than the on-voltage even if the number of operations of the charging relay 31 increases. Therefore, the charging relay 31 can be switched from the disconnected state to the connected state. For this reason, at step S112, the CPU determines whether the voltage of the auxiliary battery 6 cannot switch the charging relay 31 from the disconnected state to the connected state, rather than determining whether the voltage of the auxiliary battery 6 supplied to the charging relay 31 is less than the voltage Va, for example.

[0055] return Figure 2 If it is determined that the voltage of the auxiliary battery 6 is less than the predetermined voltage ("Yes" in step S112), the CPU included in the ECU 10 determines whether a voltage is applied to the inlet of the charger 2 by applying a voltage from the external device 900 to the inlet 1 using the detection result of the voltage sensor 26 (step S113).

[0056] If it is judged that the voltage is applied to the inlet of the charger 2 ("Yes" in step S113), the CPU included in the ECU 10 controls the sub DC-DC converter 25 so that the sub DC-DC converter 25 is activated (step S114). This applies a voltage suitable for charging the auxiliary battery 6 to the auxiliary battery 6. The voltage of the auxiliary battery 6 is supplied to the ECU 10, which in turn applies the voltage from the auxiliary battery 6 to the components to be controlled (e.g., the charging relay 31, the system main relay 32) in response to the program execution.

[0057] If it is judged that the sub-DC-DC converter 25 is not activated ("No" in step S111), if it is judged that the voltage of the auxiliary battery 6 is not less than the predetermined voltage ("No" in step S112), if it is judged that no voltage is applied to the inlet of the charger 2 (No in step S113), or after step S114, the CPU included in the ECU 10 judges whether the voltage of the auxiliary battery 6 is greater than or equal to the predetermined voltage (step S116).

[0058] Note that if the sub-DC-DC converter 25 is activated in step S114 and the voltage of the auxiliary battery 6 is thereby increased to be greater than or equal to the predetermined voltage, step S116 is "Yes". If it is determined in step S111 that the sub-DC-DC converter 25 is not activated, and it is determined in step S112 that the voltage of the auxiliary battery 6 is not less than the predetermined voltage, then in step S114 the sub-DC-DC converter 25 is not activated, but step S116 is "Yes".

[0059] If it is determined that the voltage of the auxiliary battery 6 is greater than or equal to the predetermined voltage ("Yes" in step S116), the CPU included in the ECU 10 turns on the charging relay 31, that is, controls the charging relay 31 so that the charging relay 31 is switched from the disconnected state to the connected state (step S117). Specifically, by performing this control, the ECU 10 applies the voltage of the auxiliary battery 6 to the charging relay 31 as the operating voltage of the charging relay 31.

[0060] If it is determined that the voltage of the auxiliary battery 6 is not greater than or equal to the predetermined voltage (NO in step S116), then after step S117, the CPU included in the ECU 10 returns the process to the upper processing that calls the battery charging start processing.

[0061] This increases the voltage for operating the charging relay 31 to be greater than or equal to a predetermined voltage required for the charging relay 31 to switch from the disconnected state to the connected state. As a result, the charging relay 31 can be reliably switched from the disconnected state to the connected state.

[0062] [Example 2]

[0063] In Embodiment 1, when it is judged that the voltage supplied to the charging relay 31 is greater than or equal to the predetermined voltage by actually detecting the voltage of the auxiliary battery 6, the charging relay 31 is switched to the connection state. In Embodiment 2, after a predetermined period of time has elapsed from the start of the supply of electric power from the sub-DC-DC converter 25 to the auxiliary battery 6, the voltage supplied to the charging relay 31 is deemed to be greater than or equal to the predetermined voltage, and the charging relay 31 is allowed to switch to the connection state.

[0064] Figure 4: is a flowchart showing the flow of battery charging start processing according to Embodiment 2. Figure 4 , calling and executing the battery charging start process from the upper layer process at a predetermined interval. Processing steps S121, S123 and S124 are the same as those in reference Figure 2 The described processing steps S111 , S113 , and S114 are the same, and therefore redundant descriptions will not be repeated.

[0065] After step S124, the CPU included in the ECU 10 starts counting by the timer. In other words, counting of the elapsed time period starts at the moment when the sub DC-DC converter 25 applies a voltage suitable for charging the auxiliary battery 6 to the auxiliary battery 6.

[0066] The CPU included in the ECU 10 determines whether the elapsed time period counted by the timer indicates that a predetermined time period has elapsed since the sub-DC-DC converter 25 applied the voltage to the auxiliary battery 6 (step S126). The predetermined time period is long enough so that the voltage of the auxiliary battery 6 is greater than or equal to 100% after the sub-DC-DC converter 25 applies the voltage to the auxiliary battery 6. Figure 2 In practice, when the sub-DC-DC converter 25 applies voltage to the auxiliary battery 6, the voltage of the auxiliary battery 6 quickly becomes equal to the supply voltage of the sub-DC-DC converter 25. Therefore, the predetermined time period is about several minutes at most.

[0067] If it is determined that the timed elapsed time period has passed the predetermined time period ("YES" in step S126), the CPU included in the ECU 10 turns on the charging relay 31, and Figure 2 The ECU 10 controls the charging relay 31 so that the charging relay 31 is switched from the disconnected state to the connected state (step S127). Specifically, by executing this control, the ECU 10 applies the voltage of the auxiliary battery 6 as the operating voltage of the charging relay 31.

[0068] If it is determined that the timed elapsed time period has not passed the predetermined time period (NO in step S126), then after step S127, the CPU included in the ECU 10 returns the processing to the upper layer processing that called the battery charging start processing.

[0069] This increases the voltage for operating the charging relay 31 to be greater than or equal to a predetermined voltage required for the charging relay 31 to switch from the disconnected state to the connected state. As a result, the charging relay 31 can be reliably switched from the disconnected state to the connected state.

[0070] [Modifications]

[0071] (1) In the above embodiments, Figure 2 and Figure 3 As shown, the predetermined voltage is constant. However, the present disclosure is not limited thereto. The predetermined voltage may increase in response to the number of operations of the charging relay 31. In this case, the predetermined voltage is greater than Figure 3 The on-voltage in response to the number of operations of the charging relay 31 is shown.

[0072] (2) In the above embodiment, if Figure 1 As shown, when the voltage of the auxiliary battery 6 or the sub-DC-DC converter 25 is applied to the ECU 10, the ECU 10 outputs a voltage for switching the charging relay 31, which is a component to be controlled, from a disconnected state to a connected state. However, the present disclosure is not limited thereto. The voltage (e.g., 5V) from the ECU 10 may be applied to the base of the transistor, and the transistor may thereby apply the voltage of the auxiliary battery 6 or the sub-DC-DC converter 25 to the charging relay 31.

[0073] (3) In the above embodiment, if Figure 1 As shown, the sub-DC-DC converter 25 is disposed inside the charger 2 . However, the present disclosure is not limited thereto. The sub-DC-DC converter 25 may be disposed outside the charger 2 .

[0074] (4) In the above embodiment, if Figure 1 As shown, the charging system 11 includes the auxiliary battery 6. However, the present disclosure is not limited thereto. The charging system 11 may not include the auxiliary battery 6.

[0075] (5) In the above embodiment, if Figure 1 As shown, the external power is AC power. However, the present disclosure is not limited thereto. The external power may be DC power.

[0076] (6) In the above embodiments, for example, solar cells or fuel cells may be connected in parallel. Figure 1 between the charger 2 and the charging relay 31.

[0077] (7) In the above embodiment, if Figure 2 As shown in step S112 and step S114, if the voltage of the auxiliary battery 6 is less than a predetermined voltage at the start of external charging, the sub-DC-DC converter 25 is activated. However, the present disclosure is not limited thereto. If the voltage at which the charging relay 31 switches from the disconnected state to the connected state at the start of external charging is less than the upper limit range of the voltage variation of the auxiliary battery 6, the sub-DC-DC converter 25 may be activated. Alternatively, the sub-DC-DC converter 25 may be continuously activated at the start of external charging.

[0078] (8) In the above embodiment, the charging relay 31 is a relay whose terminals are connected when voltage is applied to the coil (power on) and whose terminals are disconnected when no voltage is applied to the coil (power off). However, the present disclosure is not limited to this. The charging relay 31 may be a latching relay whose terminals are connected when voltage is applied to the set coil and keep the terminals connected even when voltage is no longer applied. In this case, when voltage is applied to the reset coil, the terminals are disconnected.

[0079] (9) In the above embodiment, if Figures 1 to 4 As shown, at the start of external charging, the voltage of the auxiliary battery 6 is increased by activating the sub DC-DC converter 25. However, the present disclosure is not limited thereto. At the start of external charging, if the system main relay 32 is in a connected state, the voltage of the auxiliary battery 6 can be increased by driving the main DC-DC converter 7.

[0080] (10) The above-described embodiments may be regarded as disclosure of the charging system 11 , disclosure of the charger 2 , disclosure of the vehicle 100 , or disclosure of a method or program for controlling the charging system 11 , the charger 2 , or the vehicle 100 .

[0081] [Overview]

[0082] (1) Figure 1 As shown, the charging system 11 includes: a main battery 4, which stores electricity for driving the vehicle 100; an inlet 1, which is connected to a charging connector 910 for supplying electricity to charge the main battery 4; a charging relay 31, which switches the path of electricity from the inlet 1 to the main battery 4 between a connected state and a disconnected state; a sub-DC-DC converter 25, which steps down the voltage of the electricity from the inlet 1 to an auxiliary voltage (for example, a voltage suitable for charging the auxiliary battery 6); and an ECU 10, which controls the charging relay 31 and the sub-DC-DC converter 25.

[0083] like Figure 2 and 4 As shown, the ECU 10 controls the sub-DC-DC converter 25 so that the sub-DC-DC converter 25 starts to step down the voltage of the power from the inlet 1 to the auxiliary voltage (for example, Figure 2 Step S114, Figure 4 before the charging relay 31 is switched to the connected state, the power from the sub-DC-DC converter 25 is supplied to the charging relay 31 as the operating power for switching to the connected state (for example, Figure 2 Step S114, Figure 4 and using the operating power to control the charging relay 31 so that the charging relay 31 is switched from the disconnected state to the connected state (eg, Figure 2 Step S117, Figure 4 Step S127).

[0084] This allows: after power is supplied from the external power to the vehicle 100 via the inlet 1 and before external charging starts, the sub DC-DC converter 25 starts to step down the voltage to the auxiliary voltage; the charging relay 31 is supplied with power from the sub DC-DC converter 25 as operating power for switching to the connected state before switching to the connected state; and the charging relay 31 switches from the disconnected state to the connected state using the operating power. As a result, it is possible to prevent the charging relay 31 from failing to switch to the connected state before external charging starts.

[0085] (2) Figure 1 As shown, the charging system 11 may further include an auxiliary battery 6 storing power having an auxiliary voltage, wherein the sub DC-DC converter 25 may be connected in parallel to the auxiliary battery 6 .

[0086] (3) Figure 1 As shown, the charging system 11 may further include a main DC-DC converter 7 that is different from the sub-DC-DC converter 25 and steps down the voltage of the power stored in the main battery 4 to an auxiliary voltage to supply the power stored in the main battery 4 to the auxiliary battery 6.

[0087] (4) Figure 4 As shown, the ECU 10 may control the sub DC-DC converter 25 so that the sub DC-DC converter 25 is activated to supply operating power to the charging relay 31 regardless of the voltage of the auxiliary battery 6 (eg, step S124 ).

[0088] (5) Figure 1 As shown, the charging system 11 may further include a voltage sensor 61 for sensing the voltage of the auxiliary battery 6. Figure 2 As shown, if the voltage sensed by the voltage sensor 61 is less than a predetermined voltage (for example, if Figure 2 If step S112 of the control circuit 10 is “Yes”), the ECU 10 may control the sub-DC-DC converter 25 so that the sub-DC-DC converter 25 is actuated to supply the operating power to the charging relay 31 (for example, Figure 2 Step S114).

[0089] (6) Figure 2 As shown, after the sub-DC-DC converter 25 is activated, when the voltage sensed by the voltage sensor 61 thereafter is greater than or equal to a predetermined voltage (for example, if Figure 2 If step S116 is “YES”), the ECU 10 may supply the operating power to the charging relay 31 (for example, Figure 2Step S117).

[0090] (7) Figure 4 As shown, after a predetermined period of time has passed since the activation of the sub-DC-DC converter 25 (for example, if Figure 4 If step S126 is “YES”), the ECU 10 may supply the operating power to the charging relay 31 (for example, Figure 4 Step S117).

[0091] (8) Figure 1 As shown, the charger 2 includes: a high-voltage DC-DC converter 24 that supplies power from the inlet 1 connected to the charging connector 910 to the charging relay 31, the charging connector 910 is used to supply power to charge the main battery 4 storing power for driving the vehicle 100, and the charging relay 31 switches the path of the power to the main battery 4 between a connected state and a disconnected state; and a sub-DC-DC converter 25 that steps down the voltage of the power from the inlet 1 to an auxiliary voltage (for example, a voltage suitable for charging the auxiliary battery 6). Figure 2 and Figure 4 As shown, after receiving power from the inlet 1, the sub DC-DC converter 25 steps down the voltage of the power from the inlet 1 to the auxiliary voltage, and before the charging relay 31 switches to the connection state, the power from the inlet 1 is supplied to the charging relay 31 as the operating power for switching to the connection state (for example, Figure 2 Step S114, Figure 4 Step S124).

[0092] This can prevent the charging relay 31 from failing to switch to the connected state before external charging starts.

[0093] (9) Figure 1 As shown, in a method for controlling a charging system 11, the charging system 11 includes: a main battery 4, which stores electricity for driving the vehicle 100; an inlet 1, which is connected to a charging connector 910 for supplying electricity to charge the main battery 4; a charging relay 31, which switches the path of electricity from the inlet 1 to the main battery 4 between a connected state and a disconnected state; a sub-DC-DC converter 25, which steps down the voltage of the electricity from the inlet 1 to an auxiliary voltage (for example, a voltage suitable for charging the auxiliary battery 6); and an ECU 10, which controls the charging relay 31 and the sub-DC-DC converter 25.

[0094] like Figure 2 and Figure 4As shown, the method includes: controlling the sub-DC-DC converter 25 by the ECU 10 so that the sub-DC-DC converter 25 starts to step down the voltage of the power from the inlet 1 to the auxiliary voltage (for example, Figure 2 Step S114, Figure 4 before the charging relay 31 is switched to the connected state, the power from the sub-DC-DC converter 25 is supplied to the charging relay 31 as the operating power for switching to the connected state (for example, Figure 2 Step S114, Figure 4 and using the operating power to control the charging relay 31 so that the charging relay 31 is switched from the disconnected state to the connected state (eg, Figure 2 Step S117, Figure 4 Step S127).

[0095] This can prevent the charging relay 31 from failing to switch to the connected state before external charging starts.

[0096] While the present disclosure has been described and illustrated in detail, it should be clearly understood that the present disclosure is by way of illustration and example only and is not to be regarded as limiting, the scope of the present disclosure being interpreted by the terms of the appended claims.

Claims

1. Charging system, including: a main battery, which stores electricity for driving the vehicle; an inlet connected to a charging connector for supplying power to charge the main battery; a charging relay that switches a path of power from the inlet to the main battery between a connected state and a disconnected state; an inlet-side voltage converter that steps down the voltage of the power from the inlet to an auxiliary voltage; a controller that controls the charging relay and the inlet-side voltage converter; an auxiliary battery storing electric power having the auxiliary voltage, the inlet-side voltage converter being connected in parallel to the auxiliary battery; as well as A voltage sensor is provided to sense the voltage of the auxiliary battery, wherein: The controller: controlling the inlet-side voltage converter so that the inlet-side voltage converter starts to step down the voltage of the power from the inlet to the auxiliary voltage after receiving the power from the inlet; supplying power from the inlet-side voltage converter to the charging relay as operating power for switching to the connected state before the charging relay switches to the connected state; and controlling the charging relay so that the charging relay switches from the disconnected state to the connected state using the operating power; Wherein, when the voltage sensed by the voltage sensor is less than a predetermined voltage, the controller controls the inlet side voltage converter so that the inlet side voltage converter is actuated to supply power from the inlet side voltage converter to the charging relay, and the predetermined voltage is greater than the voltage required for the charging relay to switch from the disconnected state to the connected state in response to the number of operations of the charging relay, and increases in response to the number of operations of the charging relay.

2. The charging system according to claim 1, further comprising: A main battery side power converter is different from the inlet side voltage converter and steps down the voltage of the power of the main battery to the auxiliary voltage to supply the power stored in the main battery to the auxiliary battery.

3. The charging system according to claim 1, wherein: After the inlet-side voltage converter is activated, when the voltage sensed by the voltage sensor is greater than or equal to the predetermined voltage, the controller supplies the operating power to the charging relay.

4. The charging system according to claim 1, wherein: The controller supplies the operating power to the charging relay after a predetermined period of time has elapsed from activation of the inlet-side voltage converter.

5. Charger, including: a power supply unit that supplies power from an inlet connected to a charging connector for supplying power to charge a main battery storing power for running the vehicle to a charging relay that switches a path of power to the main battery between a connected state and a disconnected state; as well as an inlet-side voltage converter that steps down the voltage of the power from the inlet to an auxiliary voltage, wherein After receiving power from the inlet, the inlet-side voltage converter steps down the voltage of the power from the inlet to the auxiliary voltage so that the power from the inlet is supplied to the charging relay as operating power for switching to the connected state before the charging relay switches to the connected state; and The inlet side voltage converter is actuated to supply power from the inlet side voltage converter to the charging relay when a voltage sensed by a voltage sensor configured to sense a voltage of an auxiliary battery connected in parallel with the inlet side voltage converter is less than a predetermined voltage, wherein the predetermined voltage is greater than a voltage required for the charging relay to switch from the disconnected state to the connected state in response to the number of operations of the charging relay and increases in response to the number of operations of the charging relay.

6. A method for controlling a charging system, The charging system comprises: a main battery, which stores electricity for driving the vehicle; an inlet connected to a charging connector for supplying power to charge the main battery; a charging relay that switches a path of power from the inlet to the main battery between a connected state and a disconnected state; an inlet-side voltage converter that steps down the voltage of the power from the inlet to an auxiliary voltage; an auxiliary battery storing electric power having the auxiliary voltage, wherein the inlet-side voltage converter is connected in parallel to the auxiliary battery; a voltage sensor that senses a voltage of the auxiliary battery; and A controller controls the charging relay and the inlet-side voltage converter, the method comprising: Through the controller, controlling the inlet-side voltage converter so that the inlet-side voltage converter starts to step down the voltage of the power from the inlet to the auxiliary voltage after receiving the power from the inlet; supplying power from the inlet-side voltage converter to the charging relay as operating power for switching to the connected state before the charging relay switches to the connected state; controlling the charging relay so that the charging relay switches from the disconnected state to the connected state using the operating power; and When the voltage sensed by the voltage sensor is less than a predetermined voltage, the inlet side voltage converter is controlled so that the inlet side voltage converter is actuated to supply power from the inlet side voltage converter to the charging relay, wherein the predetermined voltage is greater than a voltage required for the charging relay to switch from the disconnected state to the connected state in response to the number of operations of the charging relay, and increases in response to the number of operations of the charging relay.

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