KR20220158505A - Bidirectional charging system for vehicle - Google Patents

Abstract

Disclosed is a bidirectional charging system for a vehicle, capable of conducting power conversion to provide power stored in a battery in the vehicle to a system, load, or motor provided in the vehicle using a minimum of electrical components. The bidirectional charging system for a vehicle comprises: a first bridge circuit having a plurality of legs each including two first switching elements connected in series between both ends of a battery; a second bridge circuit having a plurality of legs each including two second switching elements connected in series between both ends of the battery; a transformer having a plurality of primary wires connected to a system or a load side and a plurality of secondary wires insulated from the plurality of primary wires; a plurality of relays selectively connecting the plurality of secondary wires to one among a connection node between two first switching elements included in one leg in the first bridge circuit and a connection node between two second switching elements included in one leg in the second bridge circuit; a motor connected to each connection node of the two first switching elements included in each of the plurality of legs of the first bridge circuit to receive respective voltages of each phase; and a controller controlling connection states of the plurality of relays according to preset operating modes.

Description

Bidirectional charging system for vehicles {BIDIRECTIONAL CHARGING SYSTEM FOR VEHICLE}

The present invention relates to a bidirectional charging system for a vehicle, and more particularly, to a vehicle capable of converting power to charge a battery in a vehicle and converting power to provide power stored in a battery in a vehicle to a system, a load, or a motor included in the vehicle. It relates to a two-way charging system.

Recently, demand for electric vehicles that generate driving power by driving a motor with electric energy stored in an energy storage device such as a battery instead of a typical internal combustion engine vehicle that generates driving power through burning fossil fuels according to the global trend of reducing carbon dioxide emissions. is increasing significantly.

In the case of an electric vehicle, a battery is provided to store electric energy supplied to a motor for generating driving power of the vehicle, and an on-board charger is provided to convert external power into power used for charging the battery to charge the battery. do.

On the other hand, as the battery capacity of electric vehicles has recently increased, the development of V2G (Vehicle to Grid) or V2L (Vehicle to Load) technology for supplying the energy stored in the battery of the vehicle to the grid or electric load is required. have. In addition, torque vectoring technology is being researched and developed to secure driving stability by providing auxiliary motors to wheels connected to both sides of a driving shaft to individually control the speed of each driving wheel.

As described above, electric vehicles require circuits for various power conversions, such as a circuit for realizing V2G or V2L, a circuit for driving an auxiliary motor for torque vectoring, as well as a charger for simply charging a battery.

When these various power conversion circuits are individually provided in a vehicle, a large number of electrical parts are required to implement each power conversion circuit, and accordingly, not only the circuit structure is complicated, but also the cost for circuit implementation increases. problems can arise.

The matters described as the background art are only for improving understanding of the background of the present invention, and should not be taken as an admission that they correspond to prior art already known to those skilled in the art.

KR 10-2017-0126053 A KR 10-2013-0138954 A

Therefore, the present invention is a two-way vehicle that can implement power conversion for charging the battery in the vehicle and power conversion for providing power stored in the battery in the vehicle to the system, load, or motor provided in the vehicle using a minimum of electrical components. Providing a charging system is a technical challenge to be solved.

As a means for solving the above technical problem, the present invention,

a first bridge circuit having a plurality of legs each including two first switching elements connected in series between both ends of the battery;

a second bridge circuit having a plurality of legs each including two second switching elements connected in series between both ends of the battery;

a transformer having a plurality of primary windings connected to a system or a load side and a plurality of secondary windings insulated from the plurality of primary windings;

The plurality of secondary windings are selected from among a connection node of two first switching elements included in one leg in the first bridge circuit and a connection node between two second switching elements included in one leg in the second bridge circuit. A plurality of relays each selectively connected to one;

a motor connected to connection nodes of two first switching elements included in each of the plurality of legs of the first bridge circuit to receive voltages of each phase; and

a controller controlling the connection state of the plurality of relays according to a preset operation mode;

It provides a two-way charging system for a vehicle comprising a.

In one embodiment of the present invention, the controller, in a first operation mode of charging the battery while the vehicle is stopped and a second operation mode of supplying power from the battery to an external system or load while the vehicle is stopped, the plurality of A secondary side winding may be respectively connected to connection nodes of two first switching elements included in one leg in the first bridge circuit.

In one embodiment of the present invention, the controller may control the first switching element to rectify the voltage of the secondary side winding and provide it to the battery in the first operation mode.

In one embodiment of the present invention, in the second operation mode, the controller may control the first switching element to convert the voltage of the battery into an AC voltage and provide the converted AC voltage to the secondary winding.

In one embodiment of the present invention, in a third operation mode in which the motor is driven or power is supplied to a load while the vehicle is running, the controller includes the plurality of secondary windings in one leg in the second bridge circuit. Each of the connection nodes of the two second switching elements may be connected.

In one embodiment of the present invention, the controller controls the first switching element so that the first bridge circuit operates as an inverter generating driving power for driving the motor, and the second bridge circuit operates as the battery It is possible to control the second switching switching element to convert the voltage of AC voltage to the secondary side winding.

In one embodiment of the present invention, the first bridge circuit may include three legs, and the second bridge circuit may include two legs.

In one embodiment of the present invention, the plurality of relays connect two of the plurality of secondary windings to a connection node of two first switching elements respectively included in two legs in the first bridge circuit and the second Two three-point relays selectively connected to one of the connection nodes of two second switching elements respectively included in two legs in the bridge circuit, and one of the plurality of secondary windings to one leg in the first bridge circuit It may include one two-way relay that connects to/opens the connection node of the two included first switching elements.

According to the bidirectional charging system for a vehicle, torque vectoring for securing vehicle driving performance and power supply to a small load inside the vehicle are simultaneously performed in a motor driving/V2L mode while driving, thereby improving vehicle performance and marketability.

In addition, according to the bidirectional charging system for a vehicle, a separate inverter for the auxiliary driving motor is not required by driving the auxiliary driving motor for torque vectoring using the bridge circuit of the DC-DC converter provided in the charger. Accordingly, according to the bidirectional charging system for a vehicle, an increase in circuit size and cost due to the addition of a motor driving circuit can be suppressed.

The effects obtainable in the present invention are not limited to the effects mentioned above, and other effects not mentioned can be clearly understood by those skilled in the art from the description below. will be.

1 and 2 are circuit diagrams showing states for each operation mode of a bidirectional charging system for a vehicle according to an embodiment of the present invention.
FIG. 3 is a waveform diagram illustrating voltage/current at major positions in a circuit in a battery charging mode while the vehicle is stopped in a bidirectional charging system according to an embodiment of the present invention.
FIG. 4 is a waveform diagram illustrating voltage/current at a main position in a circuit in a V2G/V2L mode while a vehicle bidirectional charging system according to an embodiment of the present invention is stopped.

Hereinafter, a bidirectional charging system for a vehicle according to various embodiments will be described in more detail with reference to the accompanying drawings.

1 and 2 are circuit diagrams showing states for each operation mode of a bidirectional charging system for a vehicle according to an embodiment of the present invention.

1 and 2, the bidirectional charging system for a vehicle according to an embodiment of the present invention includes a plurality of legs 41 each including two first switching elements connected in series to each other between both ends of a battery 100; A first bridge circuit 40 having 42 and 43, and a second bridge circuit having a plurality of legs 51 and 52 each including two second switching elements connected in series to each other between both ends of the battery 100. 50, a transformer 30 having a plurality of primary windings connected to the system or load side and a plurality of secondary windings insulated from the plurality of primary windings, and one of the plurality of secondary windings, A connection node of two first switching elements included in one leg 41, 42, and 43 in one bridge circuit 40 and two second switching elements included in one leg 51 and 52 in the second bridge circuit 50 A plurality of relays (R1, R2, R3) selectively connected to one of the connection nodes of the two switching elements, and two relays included in the plurality of legs 41, 42, and 43 of the first bridge circuit 40, respectively. It consists of a controller 300 that controls the connection state of a plurality of relays (R1, R2, R3) according to a motor 200 connected to the connection node of one switching element and receiving the voltage of each phase and a preset operation mode. It can be.

In general, a bidirectional charger is a charger equipped with a DC-DC converter capable of powering in both directions, and receives AC power for battery charging from a system to compensate for the power factor and form a DC voltage (Power Factor Correction: PFC). ) circuit and a bidirectional DC-DC converter that converts the size of the DC voltage output from the power factor correction circuit into a size capable of charging the battery. For V2G or V2L operation that supplies power from the battery, the bidirectional DC-DC converter appropriately converts the voltage of the battery and the power factor correction circuit operates as an inverter to provide AC power to an external system or load. .

The bi-directional charging system according to various embodiments of the present invention may also include the bridge circuits 20 and 40 and the transformer 30 constituting the power factor correction circuit 10 and the bi-directional DC-DC converter.

The power factor correction circuit 10 may be implemented with an inductor and switching elements. The power factor correction circuit 10 shown in FIGS. 1 and 2 is shown as a circuit configuration for responding to single-phase and three-phase AC inputs.

More specifically, the power factor correction circuit 10 may have a form including a plurality of inductors having one end connected to a system or load of each phase and a plurality of switching elements constituting a bridge circuit. The other end of one inductor may be connected to a connection node of two switching elements constituting one leg 11, 12, and 13 of the bridge circuit. Both ends of each leg 11, 12, and 13 of the power factor correction circuit 10 may be connected to both ends of a capacitor Cdc for forming a DC voltage.

Due to this connection relationship, the connection relationship between the inductor and the switching circuit corresponding to each phase forms a boost converter topology applied to the conventional power factor correction circuit 10 .

Among the bridge circuits constituting the bidirectional DC-DC converter, the bridge circuit 20 directly connected to the grid or load side, that is, the power factor correction circuit 10, has a plurality of legs 21 connected in parallel to each other at both ends of the capacitor Cdc. , 22, 23), and each leg 21, 22, 23 may include two switching elements connected in series with each other.

A primary winding of the transformer 30 may be connected to a connection node of a switching element included in each of the legs 21 , 22 , and 23 .

In one embodiment of the present invention, the bridge circuit 20 connected to the primary winding of the transformer 30 of the bidirectional DC-DC converter is configured to have three legs and can be implemented to generate AC voltages of three different phases. have.

Accordingly, the bridge circuit (first bridge circuit) 40 connected to the secondary side winding of the bidirectional DC-DC converter is also for rectifying the AC voltage of three different phases scaled by the transformer 30 into a DC voltage. It may be composed of three legs (41, 42, 43).

In particular, in various embodiments of the present invention, an additional bridge circuit 50 for generating a small load power source provided inside the vehicle is added, and the phase voltage input terminal of the auxiliary motor 200 for torque vectoring is DC. -The secondary side of the transformer 30, that is, the battery side winding, which is directly connected to the battery-side bridge circuit 40 of the DC converter and constitutes a bi-directional DC-DC converter according to the operation mode by adding separate relays (R1-R3) and the bridge circuits 40 and 50 may be selectively connected.

The additional bridge circuit (second bridge circuit) 50 is for providing power to small loads used in a vehicle, and may have two legs 51 and 52 considering that most small loads are single-phase. That is, the bridge circuit 50 may be an inverter circuit that generates single-phase alternating current.

As described above, in order to transfer power between the bridge circuits 20 and 40 having at least three legs, the transformer 30 is composed of at least three primary and secondary windings, respectively, so that electromagnetic induction is formed with each other. It can be implemented as a multi-phase transformer in the form of

The battery 100 is an element that stores electric energy to provide high-voltage DC power to a motor for driving a vehicle in an eco-friendly vehicle driven by electric energy, such as an electric vehicle. The battery 100 may be charged by receiving the charging power provided through the power factor correction circuit 10 and the DC-DC converter as described above.

In one embodiment of the present invention, the battery 100 may be a power supply source for supplying power to a grid or a load through a charger capable of bi-directional powering, and is driven by an auxiliary driving motor 200 provided for torque vectoring. It may also be a power supply source that supplies energy.

In one embodiment of the present invention, the motor 200 may be an auxiliary driving motor installed on each driving wheel for torque vectoring. Of course, the motor 200 may be another motor provided in the vehicle and operated by a high voltage. In the motor 200, input terminals of each phase to which driving voltage and driving current are input may be directly connected to connection nodes of two switching elements included in each leg of the bridge circuit 40, respectively.

The relays R1 to R3 may be operated under the control of the controller 300 according to the driving mode, and the secondary side winding of the transformer 30 is a connection node of two switching elements included in each leg of the bridge circuit 40. And it may be a three-point relay selectively connected to the connection node of the two switching elements included in each leg of the bridge circuit 50.

As described above, since the bridge circuit 40 has three legs corresponding to three phases and the bridge circuit 50 can have two legs for single-phase output, one of the relays (R3) is a secondary winding. And it can be implemented as a two-way relay that determines only the connection state between the connection nodes of the two switching elements in one leg in the bridge circuit 40.

The controller 300 may receive an operation mode determined by a higher level controller based on a driving state of the vehicle and a driver's input, and may control the states of the relays R1 to R3 according to the input operation mode. In addition, the controller 300 can appropriately control the switching element included in each component to correspond to each operation mode so that powering corresponding to each operation mode can be performed.

Hereinafter, the control of the relays R1, R2, and R3 performed by the controller 300 for each operation mode and the operation control operation of each circuit will be described in detail.

The interactive charging system for a vehicle according to an embodiment of the present invention can operate in a battery charging mode while stopping, a V2G/V2L mode while stopping, and a motor driving/V2L mode while driving.

Battery charging mode while stationary

In the battery charging mode while the vehicle is stopped, the controller 300 may receive an instruction for the corresponding mode from the upper controller and control the state of the relay as shown in FIG. 1 . More specifically, the controller 300 relays ( R1, R2, R3) state can be controlled.

By this control, the secondary winding of the transformer 30 can form an electrical connection with the bridge circuit 40, and as the bridge circuit 40 operates as a rectifier, the energy transferred to the secondary winding from the system side is transferred to the battery. 100 is provided so that the battery 100 can be charged.

In this charging mode, each component circuit can operate as a component of a typical charger. That is, the controller 10 can properly control the switching elements in the power factor correction circuit 10 so that a DC voltage of a preset magnitude is applied to the capacitor Cdc, and the bridge circuit 20, the transformer 30, and the bridge The switching elements in the bridge circuits 20 and 40 can be appropriately controlled so that the output voltage and output current of the DC-DC converter constituted by the circuit 40 correspond to preset command values.

The switching device control of the power factor correction circuit 10 and the switching device control of the bridge circuits 20 and 40 provided in the DC-DC converter may be performed by various methods known in the art.

FIG. 3 is a waveform diagram illustrating voltage/current at major positions in a circuit in a battery charging mode while the vehicle is stopped in a bidirectional charging system according to an embodiment of the present invention.

As shown in (a) of FIG. 3, the voltage Vout provided to the battery 100 becomes a constant DC voltage value, and as shown in (b), the current (I( L1), I(L2), and I(L3)) appear in the form of three-phase alternating current, and (c) indicates that the charging system is constantly operating so that the output power is maximum.

In one embodiment of the present invention, since the connection node of the two switching elements in each leg 41, 42, 43 of the bridge circuit 40 is always connected to the motor input terminal, the voltage/current provided from the secondary winding of the transformer 40 It is important whether or not affects the motor. This is because, if torque is generated in the motor 200 by the supply of charging power during charging in a stopped state, the vehicle may move, causing problems such as an accident.

As shown in (d) and (e) of FIG. 3, although a small amount of current (Iu, Iv, Iw) is generated at the input terminal of the motor 200, the bridge circuit (20, 40) in the DC-DC converter ) uses a high frequency region that is much higher than the frequency for driving the motor, so it can be confirmed that the actual motor cannot be rotated (speed = 0).

V2G/V2L mode while stopped

In the V2G/V2L mode during stop, the controller 300 may control the states of the relays R1, R2, and R3 in the same manner as in the battery charging mode during stop as described above.

That is, in the V2G/V2L mode during stop, the controller 300 receives an instruction for the corresponding mode from the upper controller, controls the state of the relay as shown in FIG. 1, and directs the battery 100 side to the grid side. The power factor correction circuit 10 may be operated to control the DC-DC converter so that powering is performed and to convert the DC voltage formed in the DC capacitor Cdc into AC power corresponding to the system or load power supply.

The switching element control of the power factor correction circuit 10 applied in such reverse powering and the switching element control of the bridge circuits 20 and 40 provided in the DC-DC converter may be performed by various methods known in the art. can

FIG. 4 is a waveform diagram illustrating voltage/current at a main position in a circuit in a V2G/V2L mode while a vehicle bidirectional charging system according to an embodiment of the present invention is stopped.

As shown in (a) to (c) of FIG. 4, during the reverse operation of the DC-DC converter, the alternating current (I(L4), I( L5) and I(L6)) are provided, and a constant DC voltage Vlink may be formed in the DC capacitor Cdc by the bridge circuit 20 rectifying the voltage induced in the primary side. In addition, through a switching operation of a switching element in the power factor correction circuit 10, the direct current voltage (Vlink) may be converted into an alternating voltage/current (Vgrid/Igrid) form and provided to the system or load.

Similar to the battery charging mode, it is important whether the voltage/current provided to the secondary winding of the transformer 40 affects the motor even in the V2G/V2L mode during stopping.

As shown in (d) and (e) of FIG. 4, although a small amount of current (Iu0, Iv0, Iw0) is generated at the input terminal of the motor 200, as in the battery charging mode, the bridge in the DC-DC converter Since the switching frequency of the circuits 20 and 40 uses a high frequency region much higher than the frequency for driving the motor, it can be seen that the actual motor cannot be rotated (speed = 0).

Motor drive/V2L mode while driving

In the motor driving/V2L mode while driving, the controller 300 may receive an instruction for the corresponding mode from the upper controller and control the state of the relay as shown in FIG. 2 . More specifically, the controller 300, the relay (R1, R1, the relay (R1), so that the connection nodes of the two switching elements in the legs (51, 52) of the bridge circuit 50 and each of the secondary winding of the transformer 30 form an electrical connection with each other. The states of R2 and R3) can be controlled. When the bridge circuit 50 has two legs, the relay R3 may be in a state where the connection with the bridge circuit 40 is only open.

By this control, the secondary side winding of the transformer 30 can form an electrical connection with the bridge circuit 50, and the bridge circuit 50 converts the DC voltage of the battery 100 into an AC voltage so that the transformer 30 ) can be provided on the secondary side of Similar to the V2G/V2L mode, the controller 300 controls the DC-DC converter so that powering is performed from the battery 100 side to the grid side, and the DC voltage formed in the DC capacitor Cdc is applied to the load power supply. By operating the power factor correction circuit 10 to convert into corresponding alternating current power, power supply power can be supplied to the load inside the vehicle through a load connection port provided in the vehicle during vehicle driving.

In addition, the controller 300 may drive the motor 200 for torque vectoring during vehicle driving by controlling the bridge circuit 40 to operate as an inverter for driving the motor 200 .

As such, according to an embodiment of the present invention, torque vectoring for securing vehicle driving performance in the motor driving/V2L mode while driving and power supply to a small load inside the vehicle can be simultaneously performed.

In particular, in one embodiment of the present invention, a separate inverter for the auxiliary driving motor is not required because the auxiliary driving motor for torque vectoring is driven by utilizing the bridge circuit of the DC-DC converter provided in the charger. Accordingly, an increase in circuit size and cost due to the addition of a motor driving circuit can be suppressed.

Although the above has been shown and described in relation to specific embodiments of the present invention, it will be apparent to those skilled in the art that the present invention can be variously improved and changed within the scope of the claims. .

10: power factor correction circuit 20, 40, 50: bridge circuit
30: transformer 100: battery
200: motor for auxiliary drive 300: controller
R1-R3: relay

Claims (8)

a first bridge circuit having a plurality of legs each including two first switching elements connected in series between both ends of the battery;
a second bridge circuit having a plurality of legs each including two second switching elements connected in series between both ends of the battery;
a transformer having a plurality of primary windings connected to a system or a load side and a plurality of secondary windings insulated from the plurality of primary windings;
The plurality of secondary windings are selected from among a connection node of two first switching elements included in one leg in the first bridge circuit and a connection node between two second switching elements included in one leg in the second bridge circuit. A plurality of relays each selectively connected to one;
a motor connected to connection nodes of two first switching elements included in each of the plurality of legs of the first bridge circuit to receive voltages of each phase; and
a controller controlling the connection state of the plurality of relays according to a preset operation mode;
A two-way charging system for a vehicle comprising a. The method according to claim 1, wherein the controller,
In a first operation mode in which the battery is charged while the vehicle is stopped and in a second operation mode in which power is supplied from the battery to an external system or load while the vehicle is stopped, the plurality of secondary windings are connected to one leg in the first bridge circuit. Two-way charging system for a vehicle, characterized in that each connected to the connection node of the two first switching elements included in. The method according to claim 2, wherein the controller,
The bidirectional charging system for a vehicle, characterized in that, in the first operation mode, the first switching element is controlled to rectify the voltage of the secondary side winding and provide the rectified voltage to the battery. The method according to claim 2, wherein the controller,
The bidirectional charging system for a vehicle, characterized in that, in the second operation mode, the first switching element is controlled to convert the voltage of the battery into AC voltage and provide the converted AC voltage to the secondary winding. The method according to claim 1, wherein the controller,
In a third operation mode in which the motor is driven or power is supplied to a load while the vehicle is running, the plurality of secondary windings are respectively connected to connection nodes of two second switching elements included in one leg in the second bridge circuit. A bidirectional charging system for a vehicle, characterized in that for doing. The method according to claim 5, wherein the controller,
Controlling the first switching element so that the first bridge circuit operates as an inverter generating driving power for driving the motor;
The bi-directional charging system for a vehicle, characterized in that the second bridge circuit controls the second switching switching element to convert the voltage of the battery into AC voltage and provide it to the secondary winding. The method of claim 1,
The bi-directional charging system for a vehicle, characterized in that the first bridge circuit includes three legs, and the second bridge circuit consists of two legs. The method of claim 7,
The plurality of relays include two of the plurality of secondary windings in a connection node of two first switching elements respectively included in two legs in the first bridge circuit and two legs in the second bridge circuit, respectively. two 3-point relays selectively connected to one of the connecting nodes of the two second switching elements, and two first switching elements included in one leg of the first bridge circuit with one of the plurality of secondary windings A two-way charging system for a vehicle, characterized in that it includes one two-point relay that connects / opens to the connection node of the.

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