Electric vehicle and method for controlling charge and discharge operation of electric vehicle

Abstract

The invention discloses an electric vehicle and a method for controlling charging and discharging operations of the electric vehicle. An electric vehicle includes: an AC connector; a motor connected to the first AC terminal at a neutral point of the motor; an inverter including a plurality of first branches connected between the two DC terminals, each arm of the plurality of first branches being connected to a corresponding winding of the plurality of windings of the electric machine; a second branch, both ends of which are connected to the two DC terminals, while an arm of the second branch is connected to the second AC terminal; and a controller configured to control the switching elements of the first branch and the second branch.

Description

Technical Field

[0001] The present disclosure relates to an electric vehicle including an inverter configured to convert AC power into DC power during charging or discharging of a battery and a method for controlling charging and discharging operations of the electric vehicle. Background Art

[0002] Conventional electric vehicles are equipped with a motor configured to generate driving force and a battery configured to supply power required for the operation of the motor. The vehicle is also equipped with an on-board charger (OBC) configured to charge the battery of the vehicle using standard AC power.

[0003] An on-board charger (OBC) performs operations related to converting AC voltage into DC voltage to charge the battery of the vehicle. In addition, the OBC may perform operations related to converting DC power from the battery during discharge.

[0004] Typically, an on-board charger (OBC) consists of a power factor correction circuit (PFC) configured to correct the power factor of standard AC power and a DC / DC converter configured to convert a voltage from a link capacitor into a DC voltage required by a battery of the vehicle. Summary of the invention

[0005] The present disclosure relates to an electric vehicle capable of performing the function of the above-mentioned on-board charger (OBC) through an inverter equipped therein and a method for controlling charging and discharging operations of the electric vehicle.

[0006] According to one aspect of the present disclosure, an electric vehicle may include: an AC connector electrically connected to a first AC terminal and a second AC terminal; a motor including a plurality of windings, the motor being connected to the first AC terminal at a neutral point of the motor formed by the plurality of windings; an inverter including two DC terminals and a plurality of first branches connected between the two DC terminals, respective arms of the plurality of first branches being connected to corresponding windings among the plurality of windings; a second branch, both ends of the second branch being connected to the two DC terminals, and an arm of the second branch being connected to a second AC terminal; and a controller configured to control switching elements of the first branch and the second branch.

[0007] The AC connector may be selectively connected to an AC power source.

[0008] The controller may control the plurality of switch elements connected to the remaining branches except one of the plurality of first branches to be opened under the condition that the AC power source is connected to the AC connector.

[0009] The controller may control switching of a switch element of one branch of the plurality of first branches and a switch element of a second branch.

[0010] The AC connector may include a capacitor connected between the first AC terminal and the second AC terminal.

[0011] The AC connector may further include a resistor connected in series with the capacitor between the first AC terminal and the second AC terminal.

[0012] The electric vehicle may further include: a switch configured to selectively interconnect the neutral point and the first AC terminal according to a closed / open state of the switch.

[0013] The controller may close the switch when AC power is connected to the AC connector.

[0014] The controller may control the switching of the switch elements of the plurality of first branches under a condition that the AC power source is not connected to the AC connector.

[0015] The controller can control the switching of the switch elements of the plurality of first branches according to the driving request of the motor.

[0016] According to another aspect of the present disclosure, a method for controlling charging and discharging operations of an electric vehicle may include: disconnecting, by a controller, switching elements of the remaining first branches of an inverter except for one first branch among the multiple first branches under the condition that an AC power source is connected to an AC connector; and switching, by the controller, switching elements of the one first branch and switching elements of a second branch.

[0017] The method may further include closing, by the controller, a switch before the switch is opened, the switch being configured to interconnect a neutral point formed by a plurality of windings of the motor and the first AC terminal.

[0018] Switching the switch element of the first branch and the switch element of the second branch may include: switching the switch element of the first branch and the switch element of the second branch according to a charge request or a discharge request of the battery through a controller.

[0019] The method may further include: performing, by the controller, switching of the switching elements of the plurality of first branches under a condition that the AC power source is not connected to the AC connector.

[0020] Switching the switch elements of the plurality of first branches may include: switching the switch elements of the plurality of first branches according to a driving request of the motor through a controller.

[0021] According to various embodiments of the present disclosure as described above, through the drive inverter equipped in the electric vehicle, it is possible to convert AC power into DC power during a charging operation of a battery and convert DC power into AC power during a discharging operation of the battery.

[0022] Therefore, a separate on-board charger (OBC) for charging and discharging operations of the battery may be omitted.

[0023] Furthermore, since power conversion is performed by an inverter having a relatively large current capacity, damage caused by overcurrent during power conversion can be reduced and charging and discharging performance of a battery can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 is a diagram showing an example of a circuit configuration of an electric vehicle.

[0025] Figure 2 is a diagram showing an example of a circuit of an electric vehicle associated with charging and discharging operations of the electric vehicle.

[0026] Figure 3 yes Figure 2 Equivalent circuit diagram of the circuit.

[0027] Figure 4A and Figure 4B is a graph illustrating an exemplary charging and discharging operation of an electric vehicle.

[0028] Figure 5 is a flowchart illustrating an example of a method for controlling charging and discharging operations of an electric vehicle. DETAILED DESCRIPTION

[0029] In this specification, the term "unit" or "control unit" used in specific terms such as motor control unit (MCU), hybrid control unit (HCU), etc. is merely a term widely used to designate a controller used to control specific functions of a vehicle, and therefore does not refer to a general functional unit.

[0030] The controller may include: a communication device configured to communicate with another controller or a sensor to thereby control the function to be performed; a memory configured to store an operating system, logic commands, input / output information, etc.; and at least one processor configured to perform the judgment, calculation, determination, etc. required to control the function to be performed.

[0031] The electric vehicle and the method for controlling the charging and discharging operations of the electric vehicle disclosed herein propose that an inverter provided for driving operation performs conversion between AC power and DC power during the charging and discharging operations of the battery to replace an on-board charger (OBC), thereby enabling simplification of the configuration of the vehicle while achieving improvement in the charging and discharging performance of the vehicle.

[0032] In the following, reference will be made to Figures 1 to 3 A configuration of an electric vehicle is described, and then a method for controlling charging and discharging operations of the electric vehicle is described.

[0033] Figure 1 is a circuit diagram showing a circuit configuration of an electric vehicle. Figure 2 is a circuit diagram showing a circuit of an electric vehicle associated with charging and discharging operations of the electric vehicle. Figure 3 yes Figure 2 Equivalent circuit diagram of the circuit.

[0034] Reference Figure 1 The electric vehicle includes an AC connector 100, a motor 200, an inverter 300, a second branch 400, a controller 500, and a switch 600. Of course, Figure 1 The constituent elements associated with the description of the embodiment of the present disclosure are mainly shown, but the charging and discharging device can be actually implemented by including a larger or smaller number of constituent elements than the number of constituent elements shown. Next, each constituent element will be described in detail.

[0035] First, the AC connector 100 is electrically connected to the first AC terminal A1 and the second AC terminal A2.

[0036] The motor 200 includes a plurality of windings L1 to L3 , and is connected to a first AC terminal at a neutral point N of the motor 200 formed by the plurality of windings L1 to L3 .

[0037] The inverter 300 includes two DC terminals D1 and D2, and a plurality of first branches 310, 320, and 330 connected between the two DC terminals D1 and D2. Each arm 311, 321, and 331 of the plurality of first branches 310, 320, and 330 is connected to a corresponding winding among the plurality of windings L1 to L3. In this case, the two DC terminals D1 and D2 may be connected to the positive terminal of the battery 10.

[0038] In more detail, the plurality of switching elements S11 to S16 may be connected to the first branches 310 , 320 , and 330 , and respective arms 311 , 321 , and 331 of the first branches 310 , 320 , and 330 may be formed between corresponding ones of the switching elements S11 to S16 .

[0039] For example, the switching elements S11 and S12 may be connected to the 1-1 branch 310, and the 1-1 branch 310 may be connected to the winding L1 of the motor 200 through the arm 311 between the switching elements S11 and S12. The switching elements S13 and S14 may be connected to the 1-2 branch 320, and the 1-2 branch 320 may be connected to the winding L2 of the motor 200 through the arm 321 between the switching elements S13 and S14. Similarly, the switching elements S15 and S16 may be connected to the 1-3 branch 330, and the 1-3 branch 330 may be connected to the winding L3 of the motor 200 through the arm 331 between the switching elements S15 and S16.

[0040] Corresponding switching elements among the plurality of switching elements S11 to S16 included in each of the first branches 310, 320, and 330 may be complementarily switched to adjust the direction of current input to the battery 10 connected to the two DC terminals D1 and D2 to the switching elements S11 to S16, or to adjust the direction of current input to the first AC terminal A1 and the second AC terminal A2.

[0041] On the other hand, in addition to the first branches 310, 320 and 330 of the inverter 300, the electric vehicle may further include a second branch 400 whose both ends are connected to the two DC terminals D1 and D2, while an arm 401 of the second branch 400 is connected to the second AC terminal A2.

[0042] The plurality of switching elements S21 and S22 may be connected to the second branch 400, and the second branch 400 may be connected to the second AC terminal A2 through an arm 401 between the plurality of switching elements S21 and S22. The second branch 400 may be connected to the battery 10 through two DC terminals D1 and D2 connected to the second branch 400, and may adjust the direction of current input to the battery 10 or the direction of current input to the first AC terminal A1 and the second AC terminal A2 sides together with the plurality of first branches 310, 320, and 330 of the inverter 300.

[0043] Each of the switching elements S11 to S16 of the inverter 300 and the switching elements S21 and S22 of the second branch 400 may be implemented as an IGBT or a MOSFET, but is not limited thereto.

[0044] The closed / open states of the switching elements S11 to S16 of the inverter 300 and the switching elements S21 and S22 of the second branch 400 can be controlled by the controller 500. The controller 500 can be implemented by including at least a portion of a vehicle charge management system (VCMS), a battery management system (BMS), a motor control unit (MCU), or a vehicle control unit (VCU), or can be implemented by including a separate configuration under the condition that the separate configuration performs cooperative control together with the above configuration. However, such an embodiment is merely illustrative, and the implementation type of the controller applicable to the embodiments of the present disclosure is not limited to the above implementation type.

[0045] On the other hand, an AC power source may be selectively connected to the AC connector 100. The AC power source may be implemented as a system power source or the like, for example.

[0046] The controller 500 may control the plurality of switch elements connected to the remaining branches 310 , 320 , and 330 excluding one branch among the first branches 310 , 320 , and 330 to be turned off under the condition that the AC power source 20 is connected to the AC connector 100 .

[0047] For example, the controller 500 may control the switching of the switch elements S11 and S12 of the 1-1 branch 310 by repeatedly closing / opening under the condition that the AC power source 20 is connected to the AC connector 100, and may control the switching elements S13 and S14 of the 1-2 branch 320 and the switching elements S15 and S16 of the 1-3 branch 330 to be opened. In this case, the circuit of the electric vehicle may be as follows Figure 2 , and thus can have Figure 3 The equivalent circuit configuration is shown.

[0048] That is, the controller 500 can control the switching elements of the inverter 300 under the condition that the AC power source 20 is connected to the AC connector 100, so that the inverter 300 and the second branch 400 form a full-bridge circuit, and thus, the inverter 300 and the second branch 400 can be used as a single-phase inverter.

[0049] In this case, the controller 500 may control switching of a switch element of one of the plurality of first branches 310, 320, and 330 and the switch elements S21 and S22 of the second branch 400. In particular, the controller 500 may control the switching according to a charge request or a discharge request of the battery 10.

[0050] On the other hand, the AC connector 100 may further include a capacitor C connected between the first AC terminal A1 and the second AC terminal A2. In addition, the AC connector 100 may further include a resistor R connected in series with the capacitor C between the first AC terminal A1 and the second AC terminal A2.

[0051] That is, a capacitor filter may be formed at the AC connector 100. In this case, the AC connector 100 may smooth the DC voltage through the charging and discharging operations of the capacitor C, thereby achieving a reduction in ripples.

[0052] On the other hand, the switch 600 may be provided between the neutral point N and the first AC terminal A1, and may selectively interconnect the neutral point N and the first AC terminal A1 according to the closed / open state of the switch 600. The switch 600 may be implemented as a relay, for example, but is not limited thereto.

[0053] In this case, the controller 500 may close the switch 600 under the condition that the AC power source 20 is connected to the AC connector 100 , thereby electrically interconnecting the AC power source 20 and the battery 10 .

[0054] In a state where the AC power source 20 and the battery 10 are interconnected, the battery 10 can receive power from the AC power source 20 to be charged with the received power, or can discharge the power stored in the battery 10 to supply the discharged power to the AC power source 20 side.

[0055] During charging of the battery 10, the inverter 300 and the second branch 400 may convert the AC voltage output from the AC power source 20 into a DC voltage, and then may transmit the converted DC voltage to the positive terminal side of the battery 10. On the other hand, during discharging of the battery 10, the inverter 300 and the second branch 400 may alternately transmit the DC voltage output from the battery 10 to the first AC terminal A1 and the second AC terminal A2.

[0056] Reference Figure 1 For example, during charging of the battery 10, the current input from the AC power source 20 to the first AC terminal A1 can be input to the positive terminal of the battery 10 along the first AC terminal A1-switch 600, winding L1-arm 311 of the 1-1 branch 310-switching element S11, and the current input from the AC power source 20 to the second AC terminal A2 can be input to the positive terminal of the battery 10 along the arm 401 of the second branch 400-switching element S21.

[0057] On the other hand, during the discharge of the battery 10, the current output from the positive terminal of the battery 10 can be input to the first AC terminal A1 along the switching element S11-arm 311 of the 1-1 branch 310-winding L1-switch 600, or can be input to the second AC terminal A2 along the switching element S21-arm 401 of the second branch 400.

[0058] On the other hand, the controller 500 may control the switching of the switching elements S11 to S16 of the plurality of first branches 310 under the condition that the AC power source 20 is not connected to the AC connector 100. That is, under the condition that the AC power source 20 is not connected to the AC connector 100, the inverter 300 may be used as an inverter for three-phase driving. The controller 500 may control the switching states of the switching elements S11 to S16 of the inverter 300 according to the driving request of the motor 200.

[0059] In the following, reference will be made to Figure 4A and Figure 4B The process of charging and discharging the battery 10 through the inverter 300 and the second branch 400 is described.

[0060] Figure 4A and Figure 4B is a graph showing charging and discharging operations of an electric vehicle.

[0061] exist Figure 4A and Figure 4B , a graph is shown having a vertical axis representing the voltage Vbat of the battery 10, the current Iac of the AC power source 20, and the state of charge (SOC) of the battery 10 and a horizontal axis representing time during the charging and discharging operations of the battery 10.

[0062] First, refer to Figure 4A , shows changes in the voltage Vbat of the battery 10, the current Iac of the AC power source 20, and the SOC of the battery 10 during the charging operation of the battery 10.

[0063] When charging control of the battery 10 starts at time t1, the AC power source 20 outputs an AC current that repeatedly changes direction, and the voltage Vbat of the battery 10 can increase, but the amplitude is small, through power conversion of the inverter 300 and the second branch 400. In this process, the SOC of the battery 10 continues to increase.

[0064] Next, refer to Figure 4B , shows changes in the voltage Vbat of the battery 10, the current Iac of the AC power source 20, and the SOC of the battery 10 during the discharge operation of the battery 10.

[0065] When the discharge control of the battery 10 starts at time t1', the voltage Vbat of the battery 10 can be reduced by power conversion of the inverter 300 and the second branch 400, but the amplitude is small, and the AC current that repeatedly changes direction is input to the AC power source 20. In this process, the SOC of the battery 10 continues to decrease.

[0066] like Figure 4A and Figure 4B As shown, the inverter 300 and the second branch 400 can perform the function of an on-board charger (OBC) configured to charge the battery 10 using power received from the AC power source 20 or supply power from the battery 10 to the AC power source 20, and therefore, the electric vehicle can omit the need to set up a separate on-board charger (OBC).

[0067] Figure 5 is a flow chart illustrating a method for controlling charging and discharging operations of an electric vehicle.

[0068] Reference Figure 5 First, the AC power source 20 is connected to the AC connector 100 (S510). In this case, the controller 500 may close the switch 600 configured to selectively interconnect the first AC terminal A1 and the neutral point N according to the closed state (S520), thereby electrically interconnecting the battery 10 and the AC power source 20.

[0069] In addition, the controller 500 may disconnect the switch elements of the remaining branches except one of the plurality of first branches 310, 320, and 330, thereby shorting the remaining branches except one of the plurality of first branches 310, 320, and 330. Thus, the single-phase inverter may be configured (S530).

[0070] When a charge request or a discharge request is generated in the above state (Yes in S540 ), the controller 500 may switch the switch element of one of the first branches 310 , 320 , and 330 that is not disconnected, thereby enabling the charging operation or the discharging operation of the battery 10 to start ( S550 ).

[0071] In some embodiments, through a drive inverter equipped in an electric vehicle, AC power may be converted into DC power during a charging operation of a battery, and DC power may be converted into AC power during a discharging operation of the battery.

[0072] Therefore, a separate on-board charger (OBC) for charging and discharging operations of the battery may be omitted.

[0073] Furthermore, since power conversion is performed by an inverter having a relatively large current capacity, damage caused by overcurrent during power conversion can be reduced and charging and discharging performance of a battery can be improved.

Claims

1. An electric vehicle, comprising: an AC connector electrically connected to the first AC terminal and the second AC terminal; an electric machine including a plurality of windings, the electric machine being connected to the first AC terminal at a neutral point defined by the plurality of windings; An inverter comprising (i) two DC terminals and (ii) a plurality of first branches connected between the two DC terminals, each of the plurality of first branches having an arm connected to a corresponding winding among the plurality of windings; a second branch connected to the two DC terminals and having an arm connected to the second AC terminal; as well as A controller controls each branch of the plurality of first branches and the plurality of switch elements of the second branch.

2. The electric vehicle according to claim 1, wherein: The AC connector is selectively connected to an AC power source.

3. The electric vehicle according to claim 2, wherein: The controller deactivates a first set of switching elements connected to a subset of the plurality of first branches and maintains activation of a plurality of switching elements of one of the plurality of first branches based on the AC power source being connected to the AC connector.

4. The electric vehicle according to claim 3, wherein: The controller switches the plurality of switching elements of the one of the plurality of first branches and the plurality of switching elements of the second branch based on the AC power source being connected to the AC connector.

5. The electric vehicle according to claim 2, wherein: The AC connector includes a capacitor connected between the first AC terminal and the second AC terminal.

6. The electric vehicle according to claim 5, wherein: The AC connector further includes a resistor connected in series with the capacitor between the first AC terminal and the second AC terminal.

7. The electric vehicle according to claim 2, further comprising: A switch selectively interconnects the neutral point and the first AC terminal based on a closed / open state of the switch.

8. The electric vehicle according to claim 7, wherein: The controller closes the switch based on the AC power source being connected to the AC connector.

9. The electric vehicle according to claim 2, wherein: The controller controls switching of the plurality of switch elements of the plurality of first branches based on the AC power source being disconnected from the AC connector.

10. The electric vehicle according to claim 9, wherein: The controller controls switching of the plurality of switch elements of the plurality of first branches based on a driving request of the motor.

11. A method for controlling an electric vehicle, comprising: deactivating, by a controller, a first set of switching elements of a subset of a plurality of first branches of an inverter of the electric vehicle based on the AC power source being connected to the AC connector, and maintaining a plurality of switching elements of one of the plurality of first branches activated; as well as The controller switches a plurality of switch elements of the one branch among the plurality of first branches of the electric vehicle and a plurality of switch elements of a second branch.

12. The method according to claim 11, further comprising: The controller closes the switch, which interconnects a neutral point defined by a plurality of windings of the motor and the first AC terminal, before the switch is opened.

13. The method according to claim 11, wherein: Switching the plurality of switch elements of the one branch among the plurality of first branches and the plurality of switch elements of the second branch comprises: The controller switches the plurality of switch elements of the one branch among the plurality of first branches and the plurality of switch elements of the second branch based on a charge request or a discharge request of the battery.

14. The method according to claim 11, further comprising: The controller switches the plurality of switch elements of the plurality of first branches based on the AC power source being disconnected from the AC connector.

15. The method according to claim 14, wherein: The plurality of switch elements for switching the plurality of first branches comprises: The controller switches the plurality of switch elements of the plurality of first branches based on a drive request of the motor.

Images