vehicle

Abstract

When driving a relay using the output voltage of a boost circuit, ensure the relay is properly connected. [Solution] Relays SMRB and SMRG are driven by the output voltage Vd of a boost circuit that increases the voltage of the auxiliary battery. The boost circuit increases the voltage while the boost command is ON (time t0 to t6). When the output voltage Vd exceeds the threshold A, the connection commands for relays SMRB, SMRP, and SMRG are sequentially turned ON. When the output voltage Vd of the boost circuit exceeds the threshold A, power is supplied to relays SMRB and SMRG, so that the relays can be driven to a fully connected state.

Description

Technical Field

[0001] This disclosure relates to a vehicle.

Background Art

[0002] Japanese Unexamined Patent Application Publication No. 2024-8531 (Patent Document 1) discloses a vehicle equipped with a power storage device (battery). In this vehicle, the DC power of the battery is converted into AC power by a power control unit to drive a driving motor. The battery and the power control unit are electrically connected via a system main relay. When the system main relay is in the connected state, power can be supplied to the driving motor.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Although not explicitly stated in Patent Document 1, a relay (system main relay) mounted on a vehicle is generally driven (connected / disconnected) using an auxiliary battery as a power source. When the operating voltage at which the relay operates stably is higher than the output voltage of the auxiliary battery, a boost circuit is used to boost the output voltage of the auxiliary battery to drive the relay.

[0005] When the output voltage of the boost circuit is low, if the energization of the relay is started, the relay may not be properly connected in some cases.

[0006] An object of this disclosure is to properly connect a relay when driving the relay using the output voltage of a boost circuit.

Means for Solving the Problems

[0007] The vehicle disclosed herein comprises a drive battery, a drive motor powered by the drive battery, a relay provided on the power line connecting the drive battery and the drive motor, an auxiliary battery, a boost circuit for boosting the voltage of the auxiliary battery, and a control device. The relay is configured to be energized and connected to the output voltage of the boost circuit. The control device starts energizing the relay when the output voltage of the boost circuit exceeds a predetermined value.

[0008] In this configuration, the relay connects when the output voltage of the boost circuit is energized. The control device starts energizing the relay when the output voltage of the boost circuit reaches a predetermined value or higher. Since the power supply to the relay starts after the output voltage of the boost circuit has reached a voltage sufficient to connect the relay, the relay can be properly connected. [Effects of the Invention]

[0009] According to this disclosure, when driving a relay using the output voltage of a boost circuit, the relay can be properly connected. [Brief explanation of the drawing]

[0010] [Figure 1] This is an overall configuration diagram of a vehicle according to an embodiment of the present disclosure. [Figure 2] This diagram explains how SMR works. [Figure 3] This flowchart shows an example of the SMR connection control process performed by the battery ECU. [Figure 4] This is a time chart for SMR connection. [Modes for carrying out the invention]

[0011] The embodiments of this disclosure will be described in detail below with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals, and their descriptions will not be repeated.

[0012] Figure 1 is an overall configuration diagram of vehicle 1 according to an embodiment of the present disclosure. In the following description, the case where vehicle 1 is an electric vehicle (BEV (Battery Electric Vehicle)) will be described as representative, but the vehicle of the present disclosure may also be a hybrid vehicle (HEV (Hybrid Electric Vehicle)) or a plug-in hybrid vehicle (PHEV (Plug-in Hybrid Electric Vehicle)).

[0013] Referring to Figure 1, Vehicle 1 comprises a battery 10, a power control unit (hereinafter also referred to as "PCU (Power Control Unit)") 20, a motor generator (hereinafter also referred to as "MG (Motor Generator)") 30, drive wheels 40, and a system main relay (SMR) 50. Vehicle 1 also comprises a smoothing capacitor 55, a battery ECU (Electronic Control Unit) 60, and a vehicle ECU 70.

[0014] Battery 10 is a power storage element configured to be rechargeable. Battery 10 is a battery pack consisting of, for example, a lithium-ion battery or a nickel-metal hydride battery. Battery 10 is configured to be rechargeable (externally charged) from a charging device (not shown). Note that Battery 10 corresponds to an example of a "drive battery" in this disclosure.

[0015] Battery 10 stores power to drive the MG30 and can supply power to the MG30 through the PCU20. Battery 10 is also charged by receiving power generated by the MG30 through the PCU20 when the MG30 is generating electricity.

[0016] The PCU20 performs bidirectional power conversion between the battery 10 and the MG30 according to control signals from the battery ECU60 or the vehicle ECU70. The PCU20 is configured, for example, to include an inverter that drives the MG30 and a converter that boosts the DC voltage supplied to the inverter to an output voltage equal to or greater than that of the battery 10.

[0017] The MG30 is, for example, a three-phase alternating current synchronous motor in which permanent magnets are embedded in the rotor. The MG30 is driven by the PCU20 to generate a rotational driving force, and the driving force generated by the MG30 is transmitted to the driving wheels 40. On the other hand, when the vehicle 1 is braked or when the acceleration is reduced on a downhill slope, the MG30 operates as a generator to perform regenerative power generation. The power generated by the MG30 is supplied to the battery 10 through the PCU20. The MG30 corresponds to the "motor for running" of the present disclosure.

[0018] The smoothing capacitor 55 is electrically connected between the positive electrode line PL and the negative electrode line NL, and smoothes the AC component of the voltage fluctuation between the positive electrode line PL and the negative electrode line NL. Note that the smoothing capacitor 55 may be included in the PCU20.

[0019] The SMR50 includes relays SMRB, SMRG, SMRP and a limiting resistor 52. The relay SMRB is provided on the positive electrode line PL that connects the positive electrode of the battery 10 and the PCU20. The relay SMRG is provided on the negative electrode line NL that connects the negative electrode of the battery 10 and the PCU20. The relay SMRP and the limiting resistor 52 are connected in series and are connected in parallel to the relay SMRG. The relays SMRB and SMRG correspond to an example of the "relay" of the present disclosure.

[0020] In the present embodiment, each relay is a mechanical relay in which a movable contact moves by the electromagnetic force to close the contact by energizing a solenoid (coil). Note that a non-contact relay (semiconductor relay) may be used for the relay SMRP. Each relay is turned on (ON) / off (OFF) in response to a control signal from the battery ECU60.

[0021] The relay SMRP and the limiting resistor 52 form a pre-charge circuit for reducing the inrush current flowing when the SMR50 is turned on. That is, when the SMR50 is turned on, after the relay SMRB is turned on and before the relay SMRG is turned on, the relay SMRP is turned on, and the smoothing capacitor 55 is pre-charged while the current is limited by the limiting resistor 52. As a result, the inrush current flowing from the battery 10 to the smoothing capacitor 55 when the SMR50 is turned on is reduced.

[0022] The auxiliary battery 100 is connected to the positive electrode line PL and the negative electrode line NL via the DC / DC converter 80. The auxiliary battery 100 is used as a power source for the auxiliary machine 200 of the vehicle 1, for example, an electric power steering. In the present embodiment, the output voltage (rated voltage) of the auxiliary battery 100 is 12 [V]. The DC / DC converter 80 charges the auxiliary battery 100 with the power of the battery 10. The battery ECU 60 controls the DC / DC converter 80 so that the SOC (State Of Charge) of the auxiliary battery 100 is maintained within a predetermined range.

[0023] The output voltage of the auxiliary battery 100 is boosted by the boost circuit 90. The relays SMRB and SMRG are driven when the output voltage of the boost circuit 90 is applied (energized). The relay SMRP is driven when the output voltage of the auxiliary battery 100 is applied (energized). A semiconductor switch (IPD (Intelligent Power Device)) 60 is provided between the boost circuit 90 and the relays SMRB and SMRG, and between the auxiliary battery 100 and the relay SMRP. When the corresponding IPD 60 is turned on (connected), the relays SMRB, SMRG, and SMRP are energized.

[0024] Both the battery ECU 60 and the vehicle ECU 70 consist of a CPU (Central Processing Unit), memory (ROM (Read Only Memory) and RAM (Random Access Memory)), and input / output ports for inputting and outputting various signals (neither is shown in the diagram). The battery ECU 60 and the vehicle ECU 70 are able to communicate with each other, for example, via a CAN (Controller Area Network).

[0025] When the power switch (start switch), not shown, is turned ON, the vehicle ECU 70 executes a process (startup process) to put vehicle 1 into a Ready-ON state. In this process, the battery ECU 60 receives a command from the vehicle ECU 70 and turns the SMR 50 ON. When the power switch is turned OFF, the vehicle ECU 70 executes a process (stop process) to put vehicle 1 into a Ready-OFF state. In this process, the battery ECU 60 receives a command from the vehicle ECU 70 and turns the SMR 50 OFF. The battery ECU 60 and the vehicle ECU 70 correspond to an example of a "control device" in this disclosure.

[0026] Figure 2 illustrates the operation of the relay SMRB. In Figure 2, the vertical axis represents the force acting on the movable core r1, and the horizontal axis represents the stroke amount of the movable core r1. When the solenoid (coil) r2 is energized, the magnetic field generated by the solenoid r2 attracts the movable core r1 to the fixed core r3. The attractive force of the movable core r1 is approximately proportional to the magnitude of the voltage (current) applied to the solenoid r2 and approximately inversely proportional to the square of the distance between the movable core r1 and the fixed core r3.

[0027] Referring to Figure 2, when a voltage is applied to the solenoid r2 of the relay SMRB, and an attractive force exceeding the preload F1 (and static friction force) of the return spring s1 is generated on the movable core r1, the movable contact mc moves from the disconnected state (A) to the contact state (B). In the contact state (B), the movable contact mc contacts the fixed contacts fc, fc, and the relay SMRB becomes connected. If the voltage applied to the solenoid r2 is sufficiently high, as shown by the dashed line in Figure 2, the attractive force on the movable core r1 becomes greater than the sum of the reaction force of the return spring s1 and the preload of the compression spring s2 F2, and the movable core r1 moves to the fully connected state (C). In the fully connected state (C), the movable core r1 contacts the fixed core r3, compressing the contact spring s2. The reaction force applied to the movable core r1 is the sum of the reaction force of the return spring s1 and the reaction force of the contact spring s2, as shown by the solid line in Figure 2, which is F3. After the relay SMRB is fully connected (C), the voltage applied to the solenoid r2 can be reduced to a voltage that maintains the attractive force of the movable core r1 at value F3.

[0028] When the voltage applied to solenoid r2 is low, the attractive force of the movable core r1 may be less than the sum of the reaction force of the return spring s1 and the preload of the compression spring s2, F2, in the contact state (B), as shown by the dashed line in Figure 2. In this case, the movable core r1 stops in the contact state (B). When the movable core r1 is stopped in the contact state (B), even if the current to solenoid r2 is stopped, the reaction force of the return spring s1 is small, so the movable core r1 may not move due to friction, etc., and the circuit breaker may not be turned off (A).

[0029] Relay SMRG has the same configuration and operation as relay SMRB. Relay SMRP also has a similar configuration, but is smaller in size than relay SMRB, and its movable core can move to a fully connected state even with a lower voltage applied to the solenoid compared to relay SMRB.

[0030] In this embodiment, when connecting relays SMRB and SMRG, IPD60 is turned ON when the output voltage of the boost circuit 90 exceeds a predetermined value, and power is supplied to relays SMRB and SMRG. This brings relays SMRB and SMRG into a fully connected state (C), ensuring that they are properly connected.

[0031] Figure 3 is a flowchart showing an example of the SMR connection control process performed by the battery ECU 60. This flowchart is executed when the power switch (not shown) is turned ON and the vehicle 1 startup process is executed. In configurations where the SMR 50 needs to be connected when the battery 10 is externally charged, this flowchart is also executed when external charging of the battery 10 is started.

[0032] First, in step 10 (hereinafter, steps are abbreviated as "S"), it is determined whether the boost command is ON or OFF. When the startup process of vehicle 1 is executed, the vehicle ECU 70 outputs a boost command and an SMR50 connection command in order to connect the SMR50. When the vehicle ECU 70 outputs a boost command, the boost command is turned ON. If the boost command is ON, it is determined to be OK in S10 and the process proceeds to S11. If the boost command is OFF, S10 is repeated until the boost command is turned ON.

[0033] In S11, the battery ECU 60 activates the boost circuit 90 to boost the output voltage of the auxiliary battery 100. In the subsequent S12, it is determined whether the output voltage Vd of the boost circuit 90 is greater than or equal to threshold A. The output voltage Vd may be detected by a voltage sensor 5 (see Figure 1) provided on the output side of the boost circuit 90. Threshold A is the voltage that can drive the relays SMRB and SMRG to a fully connected state. For example, threshold A may be 14[V]. Threshold A corresponds to the “predetermined value” in this disclosure. If the output voltage Vd exceeds threshold A, it is determined to be true in S12 and the process proceeds to S13. If the output voltage Vd is less than threshold A, S12 is repeated until the output voltage Vd is greater than or equal to threshold A.

[0034] In S13, the battery ECU60 connects the SMR50 relays sequentially. The battery ECU60 outputs ON commands to relays SMRB, SMRP, and SMRG in that order, sequentially turning on the corresponding IPD60 relays. After energizing relays SMRB, SMRP, and SMRG in that order, the process is completed.

[0035] Figure 4 is a time chart for connecting the SMR50. At time t0, the boost command changes from OFF to ON. When the boost command is ON, the boost circuit 90 operates and the output voltage Vd increases. At time t1, when the output voltage Vd exceeds threshold A, the SMR50s are connected sequentially. At time t2, relay SMRB turns ON and is connected. At time t3, relay SMRP turns ON and the smoothing capacitor 55 is pre-charged, and at time t4, relay SMRG turns ON, and at time t5, relay SMRP turns OFF. Then, at time t6, a command from the vehicle ECU 70 changes the boost command from ON to OFF, and the boosting of the boost circuit 90 stops.

[0036] According to this embodiment, the battery ECU 60 starts supplying power to relays SMRB and SMRG when the output voltage Vd of the boost circuit 90 becomes equal to or greater than the threshold A, thereby enabling the relays to be driven to a fully connected state.

[0037] In the above embodiment, the relay SMRP may be configured to be driven by the output voltage of the boost circuit 90.

[0038] The embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. The scope of the present invention is indicated by the claims rather than by the description of the embodiments above, and all modifications within the meaning and scope equivalent to the claims are intended to be included. [Explanation of symbols]

[0039] 1 Vehicle, 5 Voltage sensor, 6 IPD, 10 Battery, 20 PCU, 30 MG, 40 Drive wheels, 50 SMR, SMRB, SMRP, SMRG Relay, 52 Limiting resistor, 55 Smoothing capacitor, 60 Battery ECU, 70 Vehicle ECU, 80 DC / DC converter, 90 Boost circuit, 100 Auxiliary battery, 200 Auxiliary equipment, fc Fixed contact, mc Movable contact, NL Negative wire, PL Positive wire, r1 Movable core, r2 Solenoid (coil), r3 Fixed core, s1 Return spring, s2 Compression spring.

Claims

[Claim 1] A vehicle comprising a drive battery, a drive motor powered by the power of the drive battery, a relay provided on the power line connecting the drive battery and the drive motor, an auxiliary battery, a boost circuit for boosting the voltage of the auxiliary battery, and a control device, The relay is configured to be energized and connected to the output voltage of the boost circuit. The control device is A vehicle that starts supplying power to the relay when the output voltage of the boost circuit exceeds a predetermined value.

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