阅读说明：本技术 用于对车辆的电池充电的装置及方法 (Apparatus and method for charging battery of vehicle ) 是由 吕寅勇 崔珉诚 梁时熏 梁珍荣 于 2020-11-27 设计创作，主要内容包括：本发明涉及用于对车辆的电池充电的装置及方法。用于对车辆的电池充电的装置包括：PFC电路,所述PFC包括：整流器,其用于将AC电整流为DC电；链路电容,其用于对整流后的DC电进行平滑；双向DC-DC转换器,其包括：第一开关,其用于将PFC电路的DC电转换为AC电；变压器,其用于对在第一开关转换后的AC电的电压进行升压或降压；以及第二开关,其用于将来自变压器的AC电整流为DC电；以及控制器,其配置为：在进入电池充电模式之前,当链路电容的电压低于预定参考电压时,控制施加到第二开关的PWM信号的相位,使得通过来自电池的电力对链路电容充电。(The present invention relates to an apparatus and a method for charging a battery of a vehicle. The apparatus for charging a battery of a vehicle includes: a PFC circuit, the PFC including: a rectifier for rectifying AC power to DC power; a link capacitor for smoothing the rectified DC power; a bi-directional DC-DC converter, comprising: a first switch for converting DC power of the PFC circuit into AC power; a transformer for stepping up or stepping down a voltage of the AC power converted at the first switch; and a second switch for rectifying the AC power from the transformer into DC power; and a controller configured to: before entering the battery charging mode, when the voltage of the link capacitor is lower than a predetermined reference voltage, the phase of the PWM signal applied to the second switch is controlled such that the link capacitor is charged by power from the battery.)

1. An apparatus for charging a battery of a vehicle, comprising:

a power factor correction circuit, comprising:

a rectifier configured to rectify, into direct current, alternating current applied from a commercial alternating current power supply in a battery charging mode in which a battery of a vehicle is charged; and

a link capacitor connected in parallel to the rectifier and configured to smooth the rectified direct current;

a bi-directional dc-dc converter, comprising:

a first switch configured to convert the direct current applied from the power factor correction circuit into an alternating current;

a transformer configured to step up or down a voltage of the alternating current converted at the first switch; and

a second switch configured to rectify the alternating current applied from the transformer into direct current to charge a battery of the vehicle; and

a controller configured to: before entering the battery charging mode, when the voltage of the link capacitance is lower than a predetermined reference voltage, the phase of the PWM signal applied to the second switch is controlled such that the link capacitance is charged with the power discharged from the battery of the vehicle.

2. The apparatus for charging a battery of a vehicle according to claim 1, wherein the second switch comprises:

a first MOSFET;

a second MOSFET, wherein the first MOSFET and the second MOSFET are connected in series between a first electrode and a second electrode of a battery of the vehicle;

a third MOSFET; and

a fourth MOSFET, wherein the third MOSFET and the fourth MOSFET are connected in series between the first terminal of the first MOSFET and the second terminal of the second MOSFET;

wherein a first terminal of a primary coil of the transformer is connected to a first node between a first MOSFET and a second MOSFET;

a second terminal of the primary coil is connected to a second node between the third MOSFET and the fourth MOSFET.

3. The apparatus for charging a battery of a vehicle of claim 2, wherein the controller is configured to:

calculating a magnitude of a charging current to be applied to the link capacitance in order to charge the link capacitance to be higher than or equal to a predetermined reference voltage;

the phases of the third PWM signal for controlling the third MOSFET switch and the fourth PWM signal for controlling the fourth MOSFET switch are shifted so that a voltage corresponding to the calculated charging current is applied to the transformer.

4. The apparatus for charging a battery of a vehicle of claim 3, wherein the controller is configured to:

calculating an increment of the charging current per unit time;

the phases of the third and fourth PWM signals are shifted so that a voltage corresponding to the calculated increment of the charging current is applied to the transformer.

5. The apparatus for charging a battery of a vehicle according to claim 4, wherein:

when the voltage of the link capacitor is charged to be higher than or equal to a predetermined reference voltage, the controller is configured to control the first, second, third, and fourth PWM signals such that:

when the first MOSFET and the third MOSFET are turned on, the second MOSFET and the fourth MOSFET are turned off;

when the first MOSFET and the third MOSFET are turned off, the second MOSFET and the fourth MOSFET are turned on;

the power applied from the commercial ac power source is applied to the battery of the vehicle via a charging path including a power factor correction circuit, a first switch, a transformer, and body diodes of first, second, third, and fourth MOSFETs.

6. A method of charging a battery of a vehicle through a bi-directional dc-dc converter, the method comprising:

sensing a voltage of a link capacitor connected in parallel to an output terminal of a power factor correction circuit in synchronization with a point of time of entering a charging mode for charging a battery of a vehicle;

determining whether the sensed voltage of the link capacitance is lower than a predetermined reference voltage;

charging the link capacitor with power discharged from a battery of the vehicle by controlling a phase of a PWM signal applied to the second switch when the sensed voltage of the link capacitor is lower than a predetermined reference voltage;

charging a battery of the vehicle with power applied from a commercial ac power supply when a voltage of the link capacitor is charged to be higher than or equal to a predetermined reference voltage;

wherein the bidirectional DC-DC converter comprises:

a first switch connected to an output terminal of a power factor correction circuit configured to rectify an alternating current of a commercial alternating current power supply into a direct current and convert the direct current into an alternating current;

a transformer configured to step up or down a voltage of the alternating current converted at the first switch; and

a second switch configured to rectify the alternating current applied from the transformer into direct current to charge a battery of the vehicle.

7. The method of claim 6, wherein the second switch further comprises:

a first MOSFET;

a second MOSFET, wherein the first MOSFET and the second MOSFET are connected in series between a first electrode and a second electrode of a battery of the vehicle;

a third MOSFET; and

a fourth MOSFET, wherein the third MOSFET and the fourth MOSFET are connected in series between the first terminal of the first MOSFET and the second terminal of the second MOSFET;

wherein a first terminal of a primary coil of the transformer is connected to a first node between a first MOSFET and a second MOSFET; a second terminal of the primary coil is connected to a second node between the third MOSFET and the fourth MOSFET.

8. The method of claim 7, wherein charging the link capacitance comprises:

calculating a magnitude of a charging current to be applied to the link capacitance in order to charge the link capacitance to be higher than or equal to a predetermined reference voltage;

the phases of the third PWM signal for controlling the third MOSFET switch and the fourth PWM signal for controlling the fourth MOSFET switch are shifted so that a voltage corresponding to the calculated charging current is applied to the transformer to charge the link capacitor.

9. The method of claim 8, wherein the method comprises:

calculating a magnitude of the charging current based on an increment of the charging current per unit time;

the phases of the third and fourth PWM signals are shifted so that a voltage corresponding to the calculated increment of the charging current is applied to the transformer to charge the link capacitor.

10. The method of claim 9, wherein shifting the phases of the third and fourth PWM signals comprises:

controlling the first, second, third, and fourth PWM signals such that:

when the first MOSFET and the third MOSFET are turned on, the second MOSFET and the fourth MOSFET are turned off;

when the first MOSFET and the third MOSFET are turned off, the second MOSFET and the fourth MOSFET are turned on;

power applied from a commercial ac power source is applied to a battery of a vehicle via a charging path including a power factor correction circuit, a first switch, a transformer, and body diodes of first, second, third, and fourth MOSFETs.

Technical Field

The present invention relates to an apparatus and a method for charging a battery of a vehicle.

Background

Recently, the automobile industry is rapidly developing electric vehicles due to global warming caused by environmental pollution and exhaustion of fossil fuels. Major automobile manufacturers around the world are currently researching and developing electric vehicles as major vehicles.

An Electric Vehicle (EV) may be driven by accumulating electric energy in a battery that is a rechargeable battery and by converting the accumulated electric energy into kinetic energy using a motor. At this time, the method for accumulating electric energy in the battery may be divided into a fast charging scheme in which high-voltage DC power (e.g., about 50KW or more) is directly applied to the battery and a slow charging scheme in which AC power having a commercial Alternating Current (AC) voltage (e.g., about 3-6KW) is applied to the battery.

With respect to the slow charging scheme, an on-board charger (OBC) may damage elements due to the presence of an inrush current (IR), and a precharge relay is generally provided to an input terminal to avoid such a possibility. That is, by switching the pre-charge relay to charge the link capacitor first by the external power supply before charging the battery by driving the DC-DC converter, the occurrence of inrush current (IR) is reduced when the on-board charger (OBC) is connected to the external power supply.

Meanwhile, there is a disadvantage that the precharge relay for primarily charging the link capacitor has a large size, and a design for ensuring durability is required, particularly in the case of three-phase input, three or more precharge relays are required. In addition, the conventional precharge relay has a possibility of deteriorating durability due to a continuous on/off operation.

Therefore, a new scheme for charging the link capacitance while solving the problem of the pre-charge relay is required.

The above information disclosed in this background section is only for enhancement of understanding of the background of the application and therefore the information that it may contain does not constitute prior art that is already known in this country to a person skilled in the art.

Disclosure of Invention

An exemplary apparatus for charging a battery of a vehicle includes: a PFC circuit section including: a rectifier section for: rectifying an alternating current applied from a commercial alternating current power supply into a direct current in a battery charging mode for charging a battery of a vehicle; and a link capacitor connected in parallel to the rectifier part to smooth the rectified direct current; a bi-directional DC-DC converter, comprising: a first switching section configured to convert the direct current applied from the PFC circuit section into alternating current; a transformer configured to step up or down a voltage of the alternating current converted at the first switching part; and a second switching section configured to rectify the alternating current applied from the transformer into direct current to charge a battery of the vehicle; and a controller configured to: before entering the battery charging mode, when the voltage of the link capacitor is lower than a predetermined reference voltage, the phase of the PWM signal applied to the second switching part is controlled such that the link capacitor is charged with the power discharged from the battery of the vehicle.

The second switching part may include first and second MOSFETs connected in series between first and second electrodes of a battery of the vehicle, and third and fourth MOSFETs connected in series between first and second terminals of the first and second MOSFETs. A first terminal of the primary winding of the transformer may be connected to a first node between the first MOSFET and the second MOSFET; a second terminal of the primary coil may be connected to a second node between the third MOSFET and the fourth MOSFET.

The controller may be configured to: calculating a magnitude of a charging current to be applied to the link capacitance in order to charge the link capacitance to be higher than or equal to a reference voltage; the phases of the third PWM signal for controlling the third MOSFET switch and the fourth PWM signal for controlling the fourth MOSFET switch are shifted so that a voltage corresponding to the calculated charging current is applied to the transformer.

The controller may be configured to: an increment of the charging current per unit time is calculated, and phases of the third and fourth PWM signals are shifted such that a voltage corresponding to the calculated increment of the charging current is applied to the transformer.

When the voltage of the link capacitor is charged to be higher than or equal to the predetermined reference voltage, the controller may control the first, second, third, and fourth PWM signals such that: when the first MOSFET and the third MOSFET are turned on, the second MOSFET and the fourth MOSFET are turned off; when the first MOSFET and the third MOSFET are turned off, the second MOSFET and the fourth MOSFET are turned on. The power applied from the commercial ac power source may be applied to the battery of the vehicle via a charging path including the PFC circuit section, the first switching section, the transformer, and the body diodes of the first to fourth MOSFETs.

An exemplary method of charging a battery of a vehicle with a bidirectional DC-DC converter, the bidirectional DC-DC converter comprising: a first switching section connected to an output terminal of a PFC circuit section for rectifying an alternating current of a commercial alternating current power supply into a direct current, and configured to convert the direct current into an alternating current; a transformer configured to step up or down a voltage of the alternating current converted at the first switching part; and a second switching section configured to rectify the alternating current applied from the transformer into direct current to charge a battery of the vehicle. An exemplary method comprises: sensing a voltage of a link capacitor connected in parallel to an output terminal of the PFC circuit part in synchronization with a point of time when a charging mode for charging a battery of a vehicle is entered; determining whether the sensed voltage of the link capacitance is lower than a predetermined reference voltage; charging the link capacitor with power discharged from a battery of the vehicle by controlling a phase of a PWM signal applied to the second switching part when the sensed voltage of the link capacitor is lower than a predetermined reference voltage; when the voltage of the link capacitor is charged to be higher than or equal to a predetermined reference voltage, the battery of the vehicle is charged with the electric power applied from the commercial alternating-current power supply.

The second switching section may include: first and second MOSFETs connected in series between first and second electrodes of a battery of a vehicle; and third and fourth MOSFETs connected in series between the first terminal of the first MOSFET and the second terminal of the second MOSFET. A first terminal of a primary winding of the transformer may be connected to a first node between the first MOSFET and the second MOSFET, and a second terminal of the primary winding may be connected to a second node between the third MOSFET and the fourth MOSFET.

Charging the link capacitance may include: calculating a magnitude of a charging current to be applied to the link capacitance in order to charge the link capacitance to be higher than or equal to a reference voltage; the phases of the third PWM signal for controlling the third MOSFET switch and the fourth PWM signal for controlling the fourth MOSFET switch are shifted so that a voltage corresponding to the calculated charging current is applied to the transformer to charge the link capacitor.

In calculating the magnitude of the charging current, an increment of the charging current per unit time may be calculated. In charging the link capacitor, the phases of the third and fourth PWM signals may be shifted such that a voltage corresponding to the calculated increment of the charging current is applied to the transformer to charge the link capacitor.

When the voltage of the link capacitor is charged to be higher than or equal to the reference voltage at the time of charging the battery of the vehicle, the first to fourth PWM signals may be controlled such that: when the first MOSFET and the third MOSFET are turned on, the second MOSFET and the fourth MOSFET are turned off; when the first MOSFET and the third MOSFET are turned off, the second MOSFET and the fourth MOSFET are turned on.

The power to be applied from the commercial ac power source may be applied to a battery of the vehicle via a charging path including the PFC circuit section, the first switching section, the transformer, and the body diodes of the first to fourth MOSFETs.

According to an exemplary embodiment, an inrush current (IR) may be prevented by initially charging a link capacitor without using a conventional pre-charge relay for charging the link capacitor, thereby simplifying a circuit without an additional design for control of the pre-charge relay.

Drawings

Fig. 1 is a block diagram illustrating an apparatus for charging a battery of a vehicle according to an exemplary embodiment.

Fig. 2 is a circuit diagram of the apparatus for charging a battery of a vehicle in fig. 1.

Fig. 3 is a flowchart illustrating a method for charging a battery of a vehicle according to an exemplary embodiment.

Fig. 4 to 7A, 7B, and 7C respectively show first to fourth PWM signals applied to the second switching part of fig. 2 and a transformer voltage according to the PWM signals.

Fig. 8 illustrates a voltage variation of a link capacitance that is primarily charged by discharged power of a battery of a vehicle according to an exemplary embodiment, compared to the related art.

Fig. 9A and 9B are exemplary diagrams illustrating changes in voltage and current of a link capacitance with and without primary charging of the link capacitance.

Detailed Description

The battery of the vehicle is a power source of an Electric Vehicle (EV), and may be implemented as a rechargeable battery (e.g., typically a lithium ion battery) capable of repeatedly charging and discharging electric energy. Here, the electric vehicle may include any vehicle including a battery that may store electric energy for driving the vehicle, for example, a Hybrid Electric Vehicle (HEV), a plug-in hybrid electric vehicle (PHEV), or the like. For example, a battery of a vehicle is configured by stacking battery cells therein in series, and may have an internal voltage in the range of about 240V to 413V according to a state of charge.

In order to charge a battery of a vehicle, a rapid charging scheme for charging the battery by directly applying high-voltage DC power may be effective. However, at present, an infrastructure for a rapid charging scheme is not sufficiently constructed, and thus, a scheme of charging a vehicle using a commercial AC voltage for home use is also used. For this purpose, the electric vehicle may include an on-board charger (OBC) that rectifies an AC voltage (or current) into a DC voltage (or current) and boosts or steps down the DC voltage (or current) to charge a battery of the vehicle.

Hereinafter, exemplary embodiments disclosed in the present specification will be described in detail with reference to the accompanying drawings. In this specification, the same or similar components will be denoted by the same or similar reference numerals, and a repetitive description thereof will be omitted. The terms "module" and/or "unit" of components used in the following description are only for the purpose of easily describing the present specification. Thus, these terms do not have meanings or roles that distinguish themselves from each other. In describing exemplary embodiments of the present specification, a detailed description of known technologies associated with the present invention will be omitted when it is determined that the detailed description may obscure the subject matter of the present invention. The accompanying drawings are provided only to facilitate understanding of exemplary embodiments disclosed in the specification and should not be construed as limiting the spirit disclosed in the specification, and it is to be understood that the present invention includes all modifications, equivalents, and alternatives without departing from the scope and spirit of the present invention.

Terms including ordinals (e.g., first, second, etc.) are used only to describe various components and should not be construed as limiting the components. These terms are only used to distinguish one component from another.

It will be understood that when an element is referred to as being "connected" or "coupled" to another element, it can be directly connected or coupled to the other element or be connected or coupled to the other element with the other element interposed therebetween. Further, it will be understood that when an element is referred to as being "directly connected" or "directly coupled" to another element, it can be directly connected or coupled to the other element without the other element interposed therebetween.

It will be further understood that the terms "comprises" and "comprising," when used in this specification, specify the presence of stated features, values, steps, operations, elements, components, or combinations thereof, but do not preclude the presence or addition of one or more other features, values, steps, operations, elements, components, or groups thereof.

Fig. 1 is a block diagram illustrating an apparatus for charging a battery of a vehicle according to an exemplary embodiment.

Referring to fig. 1, an apparatus 1 for charging a battery of a vehicle includes: a Power Factor Correction (PFC) circuit part 100, a bidirectional DC-DC converter 200, and a controller 300. The apparatus 1 for charging a battery of a vehicle may include a bidirectional on-board charger (OBC) that charges the battery BT of the vehicle by an input power source (e.g., commercial alternating-current power source AC) and supplies electric power discharged from the battery BT of the vehicle to an electrical load. FIG. 1 shows the link capacitance C_linkAs an element separate from the PFC circuit section 100, but is not limited thereto. Link capacitance C_linkMay be included in the PFC circuit portion 100.

A commercial alternating current power source AC is connected to an input terminal of the PFC circuit portion 100, and a bidirectional DC-DC converter 200 is connected to an output terminal of the PFC circuit portion 100. In the battery charging mode for slowly charging the battery BT of the vehicle, the PFC circuit section 100 rectifies AC power applied from a commercial alternating-current power supply AC into DC power, and transmits the DC power to the bidirectional DC-DC converter 200.

The PFC circuit part 100 is a power factor correction circuit, and may play a role in reducing power loss in converting AC power into DC power.

According to an exemplary embodiment, the PFC circuit part 100 may include a link capacitor C connected in parallel between the output terminal and the bidirectional DC-DC converter 200_link. When the link capacitance C is set before entering the battery charging mode_linkIs charged to a predetermined reference voltage V_refIn this case, an inrush current (IR) immediately after entering the battery charging mode can be prevented. The inrush current (IR) may cause degradation, performance degradation, defects, etc. of other devices.

The commercial alternating-current power supply AC may be a single-phase alternating-current power supply that can be used in homes or businesses. In korea, commercial voltage is generally single-phase AC 220V, and the voltage used may vary from country to country, but ranges from 85V to 265V. The frequency is usually 60Hz, but may be 50 Hz. An alternating current is generated by such a commercial alternating current power supply AC, and electric power of about 3kW to 6kW may be supplied to the battery BT for a vehicle. For example, the commercial alternating-current power supply AC may be an Electric Vehicle Supply Equipment (EVSE).

The battery BT for a vehicle is a power source of an Electric Vehicle (EV), and may be implemented as a rechargeable battery, for example, a lithium ion battery capable of repeatedly charging and discharging electric energy. The battery BT for a vehicle includes a plurality of batteries connected in series or in parallel, and may be a high-voltage battery in the range of about 240V to 413V according to a state of charge.

In a battery charging mode for charging the battery BT of the vehicle by the commercial alternating-current power supply AC, the bidirectional DC-DC converter 200 boosts or steps down the voltage of the DC power output from the PFC circuit section 100 to charge the battery BT of the vehicle. The bidirectional DC-DC converter 200 may charge the battery BT of the vehicle at an appropriate charging voltage of the battery BT of the vehicle (e.g., a voltage in a range of about 240V to 413V).

In the battery discharge mode for supplying the electric power discharged from the battery BT of the vehicle to the load, the bidirectional DC-DC converter 200 may boost or buck the electric power discharged from the battery BT of the vehicle and supply the boosted or stepped-down voltage to the PFC circuit section 100.

According to an exemplary embodiment, before entering the battery charging mode, when the link capacitance C connected in parallel between the output terminal of the PFC circuit part 100 and the input terminal of the bidirectional DC-DC converter 200_linkIs lower than a reference voltage V_refWhen the bidirectional DC-DC converter 200 may couple the link capacitance C with the power discharged from the battery BT of the vehicle under the control of the controller 300_linkAnd carrying out primary charging.

Generally, an apparatus for charging a battery of a vehicle utilizes a pre-charge relay (not shown) provided at an input terminal by applying AC power from a commercial alternating current power sourcePower pair link capacitance C_linkThe initial charging is performed to prevent an inrush current (IR). However, a space for precharging the relay is required in the circuit, and there is a problem such as deterioration in durability due to continuous on/off operation. According to the apparatus 1 for charging a battery of a vehicle of an exemplary embodiment, a link capacitance C may be charged by the bidirectional DC-DC converter 200_linkThe initial charging is performed without including such a precharge relay.

According to an exemplary embodiment, when the apparatus 1 for charging a battery of a vehicle is connected to a commercial alternating current power source AC (e.g., an Electric Vehicle Supply Equipment (EVSE)), the controller 300 determines the link capacitance C before charging the battery BT of the vehicle_linkWhether or not the voltage of (b) is lower than a reference voltage V_ref. When the link capacitance C_linkIs lower than a reference voltage V_refIn time, the controller 300 first controls the bidirectional DC-DC converter 200 such that the link capacitance C is_linkCharging to a reference voltage V_refThe above. When the link capacitance C_linkBecomes the reference voltage V_refIn the above, the controller 300 charges the battery BT of the vehicle with the electric power applied from the commercial alternating-current power supply AC.

Fig. 2 is a circuit diagram of the apparatus for charging a battery of a vehicle in fig. 1.

Referring to fig. 2, the PFC circuit part 100 may include a rectifier part 110 and a link capacitor part 120. In the battery charging mode, the rectifier section 110 rectifies AC power applied from a commercial alternating-current power source AC into DC power. The link capacitance section 120 includes a link capacitance C_linkThe link capacitance C_linkThe rectified DC power rectified by the rectifier unit 110 is smoothed. The link capacitance section 120 (more specifically, the link capacitance C)_link) The DC-DC converter 200 is connected in parallel between the output terminal of the PFC circuit section 100 and the bidirectional DC-DC converter.

The bidirectional DC-DC converter 200 includes a first switching part 210, a transformer 220, and a second switching part 230.

In the battery charging mode, the first switching section 210 converts DC power applied from the PFC circuit section 100 into AC power. The first switching part 210 controls under the control of the controller 300Battery BT and link capacitor C for vehicle control_linkAnd the current magnitude of the output current of the battery BT of the vehicle.

The first switching section 210 includes a fifth MOSFET Q5, a sixth MOSFET Q6, a seventh MOSFET Q7, and an eighth MOSFET Q8. Each of the fifth to eighth MOSFETs Q5, Q6, Q7 and Q8 may include a body diode.

The fifth MOSFET Q5 and the sixth MOSFET Q6 are connected in series in the link capacitor C_linkBetween the first terminal and the second terminal. The seventh MOSFET Q7 and the eighth MOSFET Q8 are connected in series between a first terminal of the fifth MOSFET Q5 and a second terminal of the sixth MOSFET Q6. At this time, a first terminal of the secondary coil 222 of the transformer 220 is connected to the third node C between the fifth MOSFET Q5 and the sixth MOSFET Q6, and a second terminal of the secondary coil 222 is connected to the fourth node D between the seventh MOSFET Q7 and the eighth MOSFET Q8.

The transformer 220 steps up or down the voltage in the battery charging mode and/or the battery discharging mode. The transformer 220 includes a primary coil 221 and a secondary coil 222.

For example, when the link capacitance C is adjusted_linkAt the time of charging, the transformer 220 boosts or lowers the voltage of the AC power applied via the second switching part 230, and transmits the boosted or lowered voltage to the first switching part 210. In another example, when charging the battery BT of the vehicle, the transformer 220 boosts or lowers the voltage of the AC power applied via the first switching part 210 and transmits the boosted or lowered voltage to the second switching part 230.

In the battery charging mode, the second switching part 230 rectifies the AC power applied from the transformer 220 into DC power to charge the battery BT of the vehicle. The second switching part 230 controls the battery BT and the link capacitor C of the vehicle under the control of the controller 300_linkAnd applied to the link capacitance C_linkCharging current I of_linkThe magnitude of the current.

The second switching section 230 may include a first MOSFET Q1, a second MOSFET Q2, a third MOSFET Q3, and a fourth MOSFET Q4. Each of the first to fourth MOSFETs Q1, Q2, Q3 and Q4 may include a body diode.

Generally, the unidirectional DC-DC converter includes unidirectional diodes at positions corresponding to the first to fourth MOSFETs Q1, Q2, Q3 and Q4, and may perform only a function of charging the battery BT of the vehicle. However, the second switching section 230 according to an exemplary embodiment includes first to fourth MOSFETs Q1, Q2, Q3 and Q4 each including a body diode, and may function as a bidirectional DC-DC converter. That is, under the control of the second switching portion 230, the battery BT of the vehicle may be charged, or the electric power discharged from the battery BT of the vehicle may be supplied to the link capacitor C_linkOr an electrical load.

The first MOSFET Q1 and the second MOSFET Q2 are connected in series between a first electrode (+) and a second electrode (-) of a battery of the vehicle. The third MOSFET Q3 and the fourth MOSFET Q4 are connected in series between the first terminal of the first MOSFET Q1 and the second terminal of the second MOSFET Q2. A first terminal of the primary winding 221 of the transformer 220 is connected to a first node a between the first MOSFET Q1 and the second MOSFET Q2, and a second terminal of the primary winding 221 is connected to a second node B between the third MOSFET Q3 and the fourth MOSFET Q4.

That is, the drain terminal of the first MOSFET Q1 is connected to the first electrode (+) of the battery BT of the vehicle, and the source terminal of the first MOSFET Q1 is connected in series with the drain terminal of the second MOSFET Q2. The first terminal of the primary coil 221 is connected to a first node A between the source terminal of the first MOSFET Q1 and the drain terminal of the second MOSFET Q2, and the source terminal of the second MOSFET Q2 is connected to a second electrode (-) of the battery of the vehicle. In addition, a drain terminal of the third MOSFET Q3 is connected to a first electrode (+) of a battery of the vehicle, and a source terminal of the third MOSFET Q3 is connected in series with a drain terminal of the fourth MOSFET Q4. The second terminal of the primary coil 221 is connected to a second node B between the source terminal of the third MOSFET Q3 and the drain terminal of the fourth MOSFET Q4, and the source terminal of the fourth MOSFET Q4 is connected to a second electrode (-) of the battery of the vehicle.

In the battery charging mode, in the first switching section 210, when the fifth MOSFET Q5 and the eighth MOSFET Q8 are turned on, the sixth MOSFET Q6 and the seventh MOSFET Q7 are turned offOff, and when the fifth MOSFET Q5 and the eighth MOSFET Q8 are turned off, the sixth MOSFET Q6 and the seventh MOSFET Q7 are turned on. Thereby, the DC power applied from the PFC circuit section 100 is converted into AC power. At this time, the first to fourth MOSFETs Q1, Q2, Q3 and Q4 included in the second switching section 230 are turned off. The alternating current converted at the first switching section 210 is coupled to the output terminal capacitance C through a charging path of a body diode including the transformer 220 and the first to fourth MOSFETs Q1, Q2, Q3 and Q4_obcAnd (6) charging. Thereafter, the capacitor C is connected to the output terminal_obcThe charged electric power is released to charge the battery BT of the vehicle.

In the battery discharge mode, in the second switching section 230, when the first MOSFET Q1 and the fourth MOSFET Q4 are turned on, the second MOSFET Q2 and the third MOSFET Q3 are turned off, and when the first MOSFET Q1 and the fourth MOSFET Q4 are turned off, the second MOSFET Q2 and the third MOSFET Q3 are turned on. Thereby, the DC power discharged from the battery BT of the vehicle is converted into AC power. At this time, the fifth to eighth MOSFETs Q5, Q6, Q7 and Q8 in the first switching section 210 are turned off. The AC power converted at the second switching section 230 is applied to the link capacitor C through a discharge path including the transformer 220 and the body diodes of the fifth to eighth MOSFETs Q5, Q6, Q7 and Q8_link. Thereafter, at the link capacitance C_linkThe charged power may be discharged to be applied to the commercial alternating-current power supply AC via the PFC circuit section 100.

According to an exemplary embodiment, before entering the battery charging mode, when the link capacitance C_linkVoltage V of_linkBelow the reference voltage V_refAt this time, the apparatus 1 for charging the battery of the vehicle may charge the link capacitance C with the electric power discharged from the battery BT of the vehicle_linkVoltage V of_linkCharged to above reference voltage V_ref. I.e. at the link capacitance C_linkVoltage V of_linkIs charged to a reference voltage V_refAfter the above, the apparatus 1 for charging the battery of the vehicle may charge the battery BT of the vehicle with the electric power applied from the commercial alternating-current power supply AC.

According to an exemplary embodiment, the first switching section 210 and the second switching section 230 may form a full-bridge converter and mayThe control is performed in a phase shift control scheme. For example, in the battery charging mode, the first switching section 210 may control the phases of the seventh MOSFET Q7 and the eighth MOSFET Q8, so that a period in which the fifth MOSFET Q5 and the eighth MOSFET Q8 are simultaneously turned on to flow a current and a period in which the sixth MOSFET Q6 and the seventh MOSFET Q7 are simultaneously turned on to flow a current may be adjusted. At this time, as the period of time for simultaneous conduction increases, the magnitude of the charging current transmitted to the transformer 220 may increase. In another example, in a battery discharge mode or on the link capacitor C_linkIn the charging, the second switching section 230 may control phases of the third MOSFET Q3 and the fourth MOSFET Q4, so that a period in which the first MOSFET Q1 and the fourth MOSFET Q4 are simultaneously turned on to allow the current to flow and a period in which the second MOSFET Q2 and the third MOSFET Q3 are simultaneously turned on to allow the current to flow may be adjusted. At this time, as the period of time for simultaneous conduction increases, the magnitude of the discharge current transmitted to the transformer 220 may increase.

Fig. 3 is a flowchart illustrating a method for charging a battery of a vehicle according to an exemplary embodiment. Fig. 4 to 7A, 7B, and 7C respectively show first to fourth PWM signals applied to the second switching part of fig. 2 and a transformer voltage according to the PWM signals. Fig. 8 illustrates a voltage variation of a link capacitance that is primarily charged by discharged power of a battery of a vehicle according to an exemplary embodiment, compared to the related art.

Hereinafter, an apparatus for charging a battery of a vehicle and a method for charging a battery of a vehicle according to exemplary embodiments will be described in detail with reference to fig. 2 to 8.

First, at step S10, the vehicle is connected to an Electric Vehicle Supply Equipment (EVSE). At this time, in step S20, the controller 300 senses the link capacitance C connected in parallel between the output terminal of the PFC circuit portion 100 and the input terminal of the bidirectional DC-DC converter 200, in synchronization with the point of time of entering the battery charging mode for charging the battery BT of the vehicle_linkVoltage V of_link。

That is, when sensing to commercial alternating current power AC (e.g., electric vehicle supply equipment: (EVSE)) receives the connection signal, the controller 300 may check the link capacitance C_linkThe state of charge of.

Subsequently, the controller 300 determines the link capacitance C at step S30_linkVoltage V of_linkWhether or not it is higher than or equal to the reference voltage V_ref。

That is, when an Electric Vehicle Supply Equipment (EVSE) and the apparatus 1 for charging a battery of a vehicle are physically connected to each other, the controller 300 determines the link capacitance C before charging the battery BT of the vehicle_linkVoltage V of_linkWhether or not it is higher than or equal to the reference voltage V_ref。

Subsequently, in step S40, when the link capacitance C is equal to_linkVoltage V of_linkBelow the reference voltage V_ref(S30-NO), the controller 300 couples the link capacitance C with the electric power discharged from the battery BT of the vehicle_linkAnd carrying out primary charging.

When in the link capacitance C_linkVoltage V of_linkBelow the reference voltage V_refWhen the device 1 for charging the battery of the vehicle is electrically connected to the commercial alternating-current power supply AC to receive electric power, due to the link capacitance C_linkVoltage V of_linkAnd a charging current I_linkMay result in damage to other components.

According to an exemplary embodiment, DC power discharged from the battery BT of the vehicle is converted into AC power by the second switching part 230 of the bidirectional DC-DC converter 200 and the converted AC power is applied to the link capacitor C via the transformer 220 and the body diode of the first switching part 210 under the control of the controller 300_link. After that, when the link capacitor C is used_linkVoltage V of_linkCharging to a reference voltage V_refAfter the above, when the apparatus 1 for charging a battery of a vehicle is electrically connected to an Electric Vehicle Supply Equipment (EVSE), an inrush current (IR) can be prevented, thereby reducing the possibility of damage to other elements.

During step S40, first at step S41, the controller 300 calculates the capacitance to be applied to the link C_linkCharging deviceElectric current I_linkAnd a charging current I per unit time_linkBy an increment of Δ I to change the link capacitance C_linkVoltage V of_linkCharging to a reference voltage V_refThe above.

For example, the controller 300 may calculate the capacitance to be applied to the link capacitance C_linkCharging current I of_linkIs 3A, to connect the link capacitor C_linkIs charged to correspond to the reference voltage V_refVoltage V of_linkAnd the charging current I per unit time can be calculated_linkThe increment Δ I of (a) is 0.1A. That is, the controller 300 controls the charging current I_linkSequentially increasing from 0A to 3A, i.e., increasing in the order of 0.1A, 0.2A, 0.3A, … …, 2.9A, 3A.

Subsequently, the controller 300 controls the first to eighth PWM signals applied to the bidirectional DC-DC converter 200 so as to pass the calculated charging current I at step S42_linkTo link capacitance C_linkAnd (6) charging.

In the battery discharge mode, in the second switching section 230, the second MOSFET Q2 and the third MOSFET Q3 are turned off when the first MOSFET Q1 and the fourth MOSFET Q4 are turned on, and the second MOSFET Q2 and the third MOSFET Q3 are turned on when the first MOSFET Q1 and the fourth MOSFET Q4 are turned off. Thereby, the DC power discharged from the battery BT of the vehicle is converted into AC power. At this time, the fifth to eighth MOSFETs Q5, Q6, Q7 and Q8 in the first switching section 210 are turned off. The AC power converted at the second switching part 230 may be applied to the link capacitor C via a discharge path including the transformer 220 and the fifth to eighth body diodes_link. The fifth to eighth body diodes may be connected in parallel with fifth to eighth MOSFETs Q5, Q6, Q7 and Q8, respectively.

For example, assume that at link capacitance C_linkVoltage V of_linkHigher than or equal to the reference voltage V_refThe controller 300 may first set the first to fourth PWM signals such that power is applied through the charging path.

Referring to fig. 4, the controller 300 may set the first to fourth PWM signals such that the first PWM signalThe PWM signal and the third PWM signal have the same duty ratio of 50% and the same phase, and the second PWM signal and the fourth PWM signal have the same duty ratio of 50% and a phase difference of 180 degrees compared to the first PWM signal and the third PWM signal, so that the power of the battery BT of the vehicle is not applied to the transformer 220 via the discharging path which is the opposite direction of the charging path. That is, the voltage V of the AC power applied from the second switching part 230 to the transformer 220_TFMay be 0V.

More specifically, in the case where the first to fourth PWM signals shown in fig. 4 are applied to the first to fourth MOSFETs Q1, Q2, Q3 and Q4, respectively, the second MOSFET Q2 and the fourth MOSFET Q4 are turned off when the first MOSFET Q1 and the third MOSFET Q3 are turned on, and the second MOSFET Q2 and the fourth MOSFET Q4 are turned on when the first MOSFET Q1 and the third MOSFET Q3 are turned off. Thus, power is not supplied via the discharge path including the first to fourth MOSFETs Q1, Q2, Q3, and Q4.

According to an exemplary embodiment, the link capacitance C is adjusted when needed_linkAt the time of charging, the controller 300 may control the voltage V of the AC power applied from the second switching part 230 to the transformer 220 by controlling the phase shift of the third and fourth PWM signals_TFThe size of (2). Referring to fig. 2, 5 and 6, in response to the phase shift of the third and fourth PWM signals, the power of the battery BT of the vehicle is applied to the transformer 220 through the second switching part 230.

More specifically, referring to fig. 5, during a first period T1_1 (in which the phase of the third PWM signal and the phase of the fourth PWM signal are shifted by PS1), the first PWM signal and the fourth PWM signal of an on level are applied to the first MOSFET Q1 and the fourth MOSFET Q4, thereby turning on the first MOSFET Q1 and the fourth MOSFET Q4, and the second PWM signal and the third PWM signal of an off level are applied to the second MOSFET Q2 and the third MOSFET Q3, thereby turning off the second MOSFET Q2 and the third MOSFET Q3. Thus, the electric power V of the battery BT of the vehicle_TF(+) is applied to the transformer 220 via the second switching part 230.

In addition, during the third period T1_3 (in which the phases of the third and fourth PWM signals are shifted by PS1), the first PWM signal of the off levelThe sign and the fourth PWM signal are applied to the first MOSFET Q1 and the fourth MOSFET Q4 to turn off the first MOSFET Q1 and the fourth MOSFET Q4, and the second PWM signal and the third PWM signal of the turn-on level are applied to the second MOSFET Q2 and the third MOSFET Q3 to turn on the second MOSFET Q2 and the third MOSFET Q3. Thus, the electric power V of the battery BT of the vehicle_TF(-) is applied to the transformer 220 via the second switching section 230.

Referring to fig. 6, when the phase shift of the third and fourth PWM signals becomes large (PS1 < PS2), the power of the battery BT of the vehicle is applied to the transformer 220 via the second switching part 230 during a period of time corresponding to the enlarged phase shift.

Referring to fig. 7A, 7B, and 7C, the controller 300 may control the phase shift of the third and fourth PWM signals to have the same effect of controlling the duty ratio of the PWM signals, thereby controlling the level of power applied to the transformer 220. Accordingly, as the phase shift of the third and fourth PWM signals becomes larger, the average value of the power applied to the transformer 220 becomes larger, and accordingly, the charging current I_linkWill increase in size. The schematic diagrams in fig. 7A, 7B, 7C correspond to the power V showing the transformer 220_TFFig. 4 to 6.

For example, in the pair-link capacitance C_linkWhen charging, the bidirectional DC-DC converter 200 may form a Phase Shift Full Bridge (PSFB) converter. The first to fourth MOSFETs Q1, Q2, Q3 and Q4 of the second switching section 230 may form a primary side full bridge circuit, the fifth to eighth MOSFETs Q5, Q6, Q7 and Q8 of the first switching section 210 are all turned off, and the fifth to eighth body diodes may form a secondary side full wave rectification circuit.

In conjunction with the PSFB converter, the controller 300 may control phases of the third PWM signal and the fourth PWM signal, and thus may control a period in which the first PWM signal and the fourth PWM signal are simultaneously turned on or a period in which the third PWM signal and the fourth PWM signal are simultaneously turned on. As the period of time during which the first PWM signal and the fourth PWM signal are simultaneously turned on increases, the voltage is applied to the link capacitor C_linkCharging current I of_linkMay increase in size.

Subsequently, the controller 300 determines the link capacitance C at step S43_linkVoltage V of_linkWhether or not it is greater than or equal to the reference voltage V_ref。

Then, when the link capacitance C_linkVoltage V of_linkGreater than or equal to a reference voltage V_refWhen (S30-YES; or S43-YES), the controller 300 electrically connects an Electric Vehicle Supply Equipment (EVSE) with the apparatus 1 for charging the battery of the vehicle at step S5, and then may enter a battery charging mode for charging the battery BT of the vehicle at step S60.

In the battery charging mode, in the first switching section 210, when the fifth MOSFET Q5 and the eighth MOSFET Q8 are turned on, the sixth MOSFET Q6 and the seventh MOSFET Q7 are turned off, and when the fifth MOSFET Q5 and the eighth MOSFET Q8 are turned off, the sixth MOSFET Q6 and the seventh MOSFET Q7 are turned on. Thereby, the DC power applied from the PFC circuit section 100 is converted into AC power. At this time, the first to fourth MOSFETs Q1, Q2, Q3 and Q4 in the second switching section 230 are turned off. The AC power converted in the first switching part 210 is applied to the output terminal capacitance C through a charging path including the transformer 220 and the first body diode to the fourth body diode_obcAnd (6) charging. Then, the capacitor C is arranged at the output terminal_obcThe charged electric power may be released to charge the battery BT of the vehicle.

Referring to fig. 8, it is found that the link capacitance C is coupled to the battery of the vehicle via the bidirectional DC-DC converter 200 using the discharge power of the battery according to an exemplary embodiment_linkThe voltage variation B obtained after the initial charging is similar to that of the link capacitor C using a conventional relay_linkThe voltage change a obtained after the charging was performed.

Fig. 9A shows a voltage change of the link capacitance with and without the initial charging of the link capacitance, and fig. 9B shows a current change of the link capacitance with and without the initial charging of the link capacitance.

Referring to fig. 9A and 9B, as shown by a dotted line, if an on-board charger (OBC) is connected to an external power supply after the link capacitor is primarily charged, the voltage V of the link capacitor_linkThe temperature of the mixture is slowly increased, and the temperature of the mixture is slowly increased,and current I_linkThere is also little variation. On the other hand, as shown by the solid line, if the on-board charger (OBC) is connected to the external power supply without primarily charging the link capacitance, the voltage V due to the link capacitance_{link_no}And current I_{link_no}May occur to damage other components.

While the invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments. On the contrary, the invention is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.