KR20190065814A - Integrated charger for electric vehicle - Google Patents

Abstract

The present invention relates to an integrated charger for an electric vehicle capable of increasing the charging capacity. The integrated charger for an electric vehicle comprises: a plurality of battery packs serving as energy storage; a plurality of inverters connected to the plurality of battery packs; and a plurality of winding wires connected to the plurality of inverters, wherein the plurality of winding wires can be used for electric motor rotation or electric power system connection.

Description

{INTEGRATED CHARGER FOR ELECTRIC VEHICLE}

The present invention relates to an integrated charger for an electric vehicle.

With the expansion of the environment-friendly automobile market, the supply of battery electric vehicles is steadily increasing. One of the biggest obstacles to the commercialization of electric vehicles is the lack of charging infrastructure. Various efforts are underway to build charging infrastructure. In addition, the V2G (Vehicle to Grid) technology that uses the unidirectional charger from the system to the electric vehicle and the energy stored in the electric car battery in conjunction with the system, and the Vehicle to Home (V2H) Development and demonstration are progressing steadily. Recently, studies are being conducted to apply electric vehicles to the smart grid area in various ways, and commercialization is accelerating due to active diffusion of rapid charging systems. For this purpose, it is essential to develop a bi-directional battery charger and a power conversion device. One of the key technologies is to shorten the charging time and improve the charging efficiency in a rapid charger. In addition to battery performance, the optimum design and optimal control technique of bi- Have been studied and applied.

International Publication No. WO 2010/057893 A1; International Publication No. WO 2011/159241 A1 US registered patent: US 9,018,809; US registered patent: US 5,099,186 US registered patent: US 8,847,555; US Published Patent: US 2011/0187185

It is an object of the present invention to provide a novel integrated charger for an electric vehicle.

An integrated charger for an electric vehicle according to an embodiment of the present invention includes a plurality of battery packs serving as energy storage, a plurality of inverters connected to the plurality of battery packs, a plurality of windings connected to the plurality of inverters, Or to power grid interconnections.

In an embodiment, there may be a connection in which the plurality of battery packs are electrically disconnected from each other or electrical flow is significantly disturbed through any impedance.

In an embodiment, the plurality of inverters may enable bi-directional power conversion using power semiconductors between the plurality of battery packs and the plurality of windings.

In an embodiment, the plurality of windings may be a conductor material that can be electrically connected directly to the plurality of inverters, which can produce a rotating magnetic flux in the motor drive mode and an electrical connection between the inverter and the power system Pathway can be provided.

In an embodiment, the plurality of windings can be connected and disconnected between the integrated charger and the power system using a separate device.

In an embodiment, the power grid interconnect may refer to an operation of receiving or receiving electrical energy between the battery and the power grid.

In the embodiment, the harmonic content rate of the voltage or the current applied to the plurality of windings is controlled by the configuration in which the plurality of battery packs are electrically separated from each other or the electric flow is significantly disturbed, The harmonic content rate of the voltage or current when a plurality of inverters are used individually can be lowered.

In an embodiment, the harmonic content rate is a ratio of all frequency components except for a fundamental frequency component that is actually visible in the plurality of windings with respect to a fundamental frequency component that the plurality of inverters intend to make through the plurality of windings.

In this embodiment, even if a failure occurs in some of the plurality of inverters, due to a configuration in which the plurality of battery packs are electrically disconnected from each other or an electric current is significantly disturbed, Motor drive or power grid connection is possible.

The integrated charger according to the embodiment of the present invention utilizes an inverter and an electric motor, which are essential for the power generation of an electric vehicle, for the purpose of charging the battery of an electric vehicle, thereby increasing the charging capacity while minimizing a separate charging device, .

The integrated charger according to the embodiment of the present invention and the operation method thereof can reduce the operating voltage of the battery and improve the harmonic characteristic of the voltage applied to the motor winding so as to reduce the overall cost for production, can do.

BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this application, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention. However, the technical features of the present embodiment are not limited to the specific drawings, and the features disclosed in the drawings may be combined with each other to constitute a new embodiment.
1 is a block diagram of an electric vehicle connected to an AC power system for battery charging.
2 is a view showing a general integrated charger.
FIG. 3 is a view showing an example of an integrated charger utilizing a winding of a general motor.
4 is an exemplary illustration of an integrated charger according to an embodiment of the present invention.
5 is a more detailed view of the configuration of inverters 110 and 120 of the integrated charger 100 shown in FIG.
FIG. 6 is a diagram illustrating an example of a motor winding voltage and current by a general integrated charger.
7 is a diagram illustrating an exemplary motor winding voltage and current of the integrated charger 100 according to an embodiment of the present invention.
FIG. 8 is a diagram illustrating an example of a pole voltage command and an output current when the SVPWM of a general integrated charger is used.
9 is a diagram illustrating an exemplary change in the frequency spectrum of the output current before and after using the SVPWM of the integrated charger 100 according to an embodiment of the present invention.
10 is a flow chart illustrating an exemplary method of operation of the integrated charger 100 according to an embodiment of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS The above and other objects, features and advantages of the present invention will be more apparent from the following detailed description taken in conjunction with the accompanying drawings, in which: FIG.

The present invention is capable of various modifications and various forms, and specific embodiments are illustrated in the drawings and described in detail in the text. It is to be understood, however, that the invention is not intended to be limited to the particular forms disclosed, but on the contrary, is intended to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention. The terms first, second, etc. may be used to describe various components, but the components should not be limited by the terms.

The terms may be used for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, the first component may be referred to as a second component, and similarly, the second component may also be referred to as a first component. It is to be understood that when an element is referred to as being "connected" or "connected" to another element, it may be directly connected or connected to the other element, . On the other hand, when an element is referred to as being "directly connected" or "directly connected" to another element, it should be understood that there are no other elements in between.

Other expressions that describe the relationship between components, such as "between" and "between" or "neighboring to" and "directly adjacent to" should be interpreted as well. The terminology used in this application is used only to describe a specific embodiment and is not intended to limit the invention. The singular expressions include plural expressions unless the context clearly dictates otherwise.

In this application, the terms "comprises" or "having" are intended to specify the presence of stated features, integers, steps, operations, components, parts, or combinations thereof, wherein one or more other features, , Steps, operations, components, parts, or combinations thereof, as a matter of course. Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Terms such as those defined in commonly used dictionaries should be construed as meaning consistent with meaning in the context of the relevant art and are not to be construed as ideal or overly formal in meaning unless expressly defined in the present application .

By using inverters and motors, which are essential for the power generation of an electric vehicle, for the purposes of battery charging of an electric vehicle, it is possible to increase the charging capacity while minimizing a separate charging device that was previously required for electric vehicle charging. The proposed invention can lower the operating voltage of the battery and improve the harmonic characteristics of the voltage applied to the motor winding, thus reducing the overall cost of production, operation and maintenance of the electric vehicle.

Instead of using fossil fuels for operation, electric vehicles store electrical energy in the battery and gain power from it. In order to store electrical energy in the battery of an electric vehicle, a method of separately installing a power conversion device therefor is mainly used. In the future, it is expected that the electric energy capacity of the electric vehicle will increase significantly in order to secure the mileage that is comparable to that of the gasoline vehicle. In order to improve the user convenience through shortening the charging time, the instantaneous charging capacity of the battery also needs to be greatly increased. Such a change entails a large capacity of the power conversion device for charging the battery, so that there are many limitations in cost, weight, and volume when a separate device is installed as in the conventional charging method. Since the essential use of the vehicle is the movement of the passenger through power generation, the electric vehicle essentially includes an electric motor and an inverter, which is a power conversion device for driving the electric motor, in order to generate power from the battery. Since these motors and inverters are capable of large-capacity power conversion, if the hardware can be used for battery charging as it is, it is expected that it will contribute to the expansion of electric vehicles by greatly reducing the burden of installing the charging device separately. The present invention relates to a circuit configuration and a control method for use with an electric motor and an inverter, which are essential components in electric power generation of an electric vehicle, for battery charging. It reduces serial connection in the battery pack and improves harmonic characteristics applied to the motor winding .

A battery charging apparatus and a control method thereof for an electric vehicle according to an embodiment of the present invention can be used to increase the capacity of a bidirectional power converter for vehicle to grid (V2G) .

1 is a block diagram of an electric vehicle connected to an AC power system for battery charging. The AC-DC power rectifier converts electrical energy from the system into a battery. It is classified as an on-board and off-board charger depending on whether the rectifier is included in the electric vehicle or not. The inverter, which performs DC-AC power conversion, is connected to the motor to convert the energy stored in the battery to the kinetic energy of the motor. The inverter also stores the recovered energy in the battery when the motor is used for braking.

A typical electric vehicle is being developed at a level where the charger has a power conversion capacity of 10kW or less and an energy capacity of the battery is 40kWh or less. However, it is expected that the battery energy capacity of electric vehicles will increase to more than 90kWh in order to secure a distance of 400 ~ 500km, which is comparable to that of ordinary gasoline vehicles. If there is no change in the charger capacity of the electric vehicle, an increase in the battery energy capacity immediately means an increase in the charging time of the electric vehicle. Therefore, it is inevitable to increase the capacity of the charger to shorten the charging time in terms of user convenience. Generally, an increase in the power conversion capacity means an increase in the weight and volume of the power conversion apparatus. Accordingly, according to the configuration as shown in FIG. 1, as the spread of electric vehicles spreads, it is expected that social / personal expenses for installation and operation of a large capacity charger will increase.

An inverter of an electric vehicle is an essential element for driving a motor and has a different meaning from a battery charging device. That is, since the charger is not expected to operate during the movement of the electric vehicle, when the weight and volume of the electric charger increase during the capacity increasing process, it is preferable to install the charger separately from the vehicle in terms of fuel economy improvement and space securing. However, in the case of an inverter, since it is an essential element for the movement of the electric vehicle, even if the electric power conversion capacity is increased for the purpose of improving the performance of the electric vehicle, it is necessarily included in the electric vehicle. In order to expand the supply of electric vehicles, the rated capacity of inverters and motors is also expected to increase. Considering the instantaneous maximum torque output of the motors, large-capacity inverters of 150 kW or more are expected to be used.

Inverters and motors are inevitable elements of an electric vehicle, and in order to provide a user experience that was possible in traditional cars, a significant increase in the power conversion capacity is inevitable. Therefore, a method of utilizing the hardware of the inverter and the motor, which are mainly used for generating power, for charging a large capacity battery, can be considered. Many researches and developments have been made on integrated chargers using inverters and motors.

2 is a view showing a general integrated charger. Referring to FIG. 2, the integrated charger may include a battery, an inverter, a motor, and a grid. An inductor / transformer is required to connect the power converter to the power system. However, a common integrated charger replaces the role of an inductor / transformer with the windings of the motor. There are a wide variety of specific ways to utilize the windings of the motor. A common characteristic is that the power converter is connected to one battery bank to perform motor driving and battery charging according to the operating mode.

FIG. 3 is a view showing an example of an integrated charger utilizing a winding of a general motor. Referring to FIG. 3, the integrated charger connects a motor having six windings and an inverter to a three-phase system to charge the battery. For example, two windings between the A leg and the B leg flow in the same direction and the same magnitude at the time of driving the motor, with respect to the dot indicating the polarity. When the battery is charged, current flows in the opposite direction and the same magnitude. This method can prevent the rotation of the motor rotor when the battery is charged. This is a bidirectional power conversion system that can charge and discharge the battery.

However, the inverters used for power conversion are connected only to one battery bank. For this reason, the level of the voltage applied to the windings at the time of driving the motor is limited to only three levels of ± Vdc (magnitude of DC voltage) and zero. In spite of using multiple windings and multiple legs compared with general 3 - phase inverter configuration for integrated charger implementation, it shows limitation on improvement of harmonic characteristics of output to motor winding. In addition, if one of the battery and the inverter is defective by having one battery bank and one inverter configuration, such an integrated charger has disadvantages in terms of reliability because it can not drive an electric vehicle.

In order to use the electric motor winding in an electric vehicle for grid connection for charging the battery, a plurality of windings are required in addition to a general three-phase winding. Otherwise, the current flowing between the battery and the system through the motor winding causes the rotation of the motor. Therefore, a separate clutch device for mechanically separating the rotation shaft of the electric motor and the vehicle drive shaft is required for charging the battery. Also, even if a clutch is used, the rotation speed of the motor under no-load condition should be limited by the mechanical limit. Therefore, the conventional integrated charger has a complicated control sequence. If the stator of the motor is designed to have three or more windings and then used for charging the battery, it is possible to charge the battery while the motor is stopped without mechanical assistance by controlling the magnetic fluxes generated in each winding to cancel each other.

The increase in the number of turns of the motor requires an increase in the number of power semiconductors of the inverter to drive the motor. And the increase in the number of windings of the motor is required in the switching process more power semiconductors than the general three-phase inverter configuration. That is, the use of a plurality of windings and a plurality of inverters is essential for the implementation of an integrated charger without motions of the motor shaft. Therefore, by utilizing such hardware conditions well, the harmonic characteristics of the inverter output applied to the windings can be improved.

4 is an exemplary illustration of an integrated charger according to an embodiment of the present invention. Referring to FIG. 4, the integrated charger 100, which improves the harmonic characteristics of the inverter output, may include a first inverter 110, a second inverter 120, and an electric motor M 130. Unlike a conventional integrated charger in which one battery bank is used, the integrated charger 100 of the present invention drives one electric motor 130 by using a plurality of separated battery packs 101 and 102 having a ground GND , Bidirectional power conversion connected to the system can be performed using the motor winding.

In an embodiment, there may be a connection where the plurality of battery packs 101, 102 are electrically disconnected from each other or electrical flow is significantly disturbed through any impedance.

In an embodiment, the plurality of inverters 110 and 120 may enable bi-directional power conversion using a power semiconductor between a plurality of battery packs 101 and 102 and a plurality of windings. In an embodiment, the plurality of windings may be a conductor material that can be electrically connected directly to the plurality of inverters 110, 120, which can create a rotating magnetic flux in the motor drive mode, and between the inverter and the power system As shown in FIG. In an embodiment, the plurality of windings can be connected and disconnected between the integrated charger and the power system using a separate device.

Each of the inverters 110 and 120 is used for each of the battery packs 101 and 102. The multiple inverter structures 110 and 120, which are separated from the DC power source, can improve the harmonic characteristic by increasing the voltage level of the inverter output applied to the motor windings. Harmonics enhancements in the inverter output can reduce overall operating costs by increasing system-wide efficiency, reducing electromagnetic interference (EMI), and reducing leakage currents.

If several isolated grounded batteries are used to drive one motor, the inverter voltage required for the same motor design can be reduced. This has the effect of reducing the number of cells connected in series within the battery pack. Although it is expected that the battery management system (BMS) circuit cost will increase when the same capacity of the battery is divided into several packs, reducing the number of serial / parallel connections of the battery cell will reduce the cost of battery production, maintenance and repair . In addition, since the batteries 101 and 102 and the inverters 110 and 120 of the multi-structure structure can drive the electric motor 130 even if only one set has a problem, the reliability of the electric vehicle can be improved Can also help.

In the embodiment, a plurality of battery packs 101 and 102 are electrically disconnected from each other, or a configuration in which the electric current is significantly disturbed, and a plurality of inverters 110 and 120, The harmonic content rate of the voltage or current can be made smaller than the harmonic content rate of the voltage or current when the plurality of inverters 110 and 120 are used individually. In an embodiment, the harmonic content rate is the ratio of all frequency components except for the fundamental frequency component actually seen in the plurality of windings for the fundamental frequency component that was intended to be produced through the plurality of inverters 110, 120 in the plurality of windings.

Even if a failure occurs in some of the plurality of inverters 110 and 120 due to the configuration in which the plurality of battery packs 101 and 102 are electrically disconnected from each other or the electrical flow is remarkably disturbed in the embodiment, By stopping the site operation, motor drive or power grid connection is possible to the remaining normal inverters.

On the other hand, in FIG. 4, the structure of two batteries 101 and 102 and two inverters 110 and 120 and six windings is described as an example, but it is understood that the structure of the present invention is not limited thereto . It should be understood that the integrated charger of the present invention may utilize batteries, inverters, and windings having a greater number to improve harmonic characteristics.

5 is a more detailed view of the configuration of inverters 110 and 120 of the integrated charger 100 shown in FIG. Referring to FIG. 5, the integrated charger 100 may include first and second inverters 110 and 120.

The first inverter 110 may include six transistors T11 to T16 and six diodes D11 to D16. In an embodiment, the first transistor T11 and the second transistor T12 may be connected in series between the two ends of the first battery pack 101. In the embodiment, corresponding diodes D11 and D12 may be connected between both ends of each of the first and second transistors T11 and T12. In the embodiment, each gate of the transistors T11 to T16 may receive the corresponding control signal S11 to S16.

The first inverter 110 includes a first transistor T11 connected between the positive voltage terminal of the first battery pack 101 and the first winding C11, a first winding C11, A third transistor T13 connected between the positive voltage terminal of the first battery pack 101 and the second winding C12 and a second transistor T12 connected between the negative voltage terminal of the pack 101 and the second winding C12 A fifth transistor T15 connected between the positive terminal of the first battery pack 101 and the third terminal T13 of the first battery pack 101, And a sixth transistor T16 connected between the third winding T13 and the negative voltage terminal of the first battery pack 101. [

In the embodiment, the negative voltage terminal of the first inverter 110 may be connected to the first ground terminal GND1.

The first inverter 110 includes a first diode D11 connected to both ends of the first transistor T11, a second diode D12 connected to both ends of the second transistor T12, A fourth diode D14 connected to both ends of the fourth transistor T14, a fifth diode D15 connected to both ends of the fifth transistor T15, And a sixth diode D16 connected to both ends of the sixth transistor T16.

The second inverter 120 may include six transistors T21 to T26 and six diodes D21 to D26. The second inverter 120 may be implemented similarly to the first inverter 110.

In an embodiment, the second inverter 120 includes a seventh transistor T21 connected between the positive voltage terminal of the second battery pack 102 and the fourth winding C21; An eighth transistor T22 connected between the negative voltage terminal of the fourth winding C21 and the negative voltage terminal of the second battery pack 102 and a seventh transistor T22 connected between the positive voltage terminal of the second battery pack 102 and the fifth winding C22, A transistor T23; A tenth transistor T24 connected between the negative voltage terminal of the fifth winding C22 and the negative voltage terminal of the second battery pack 102 and a thirteenth transistor T24 connected between the positive voltage terminal of the second battery pack 102 and the sixth winding C23. And a twelfth transistor T26 connected between the negative voltage terminal of the second battery pack 102 and the sixth winding C23 of the transistor T25.

The second inverter 120 includes a seventh diode D21 connected to both ends of the seventh transistor T21, an eighth diode D22 connected to both ends of the eighth transistor T22, A tenth diode D24 connected to both ends of the tenth transistor T24, an ninth diode D25 connected to both ends of the eleventh transistor T25, And a twelfth diode D26 connected to both ends of the twelfth transistor T26.

In the embodiment, the negative voltage terminal of the second inverter 120 may be connected to the second ground terminal GND2. Here, the second ground terminal GND2 may be electrically disconnected from the first ground terminal GND1.

Although not shown in FIG. 5, the integrated charger 100 according to the embodiment of the present invention may further include a controller for controlling the first and second inverters 110 and 120. This control device can control on / off and on / off times of the transistors T11 to T16, T21 to T26 of the first and second inverters 110 and 120, and the like.

The electric motor 130 may include six windings C11, C12, C13, C21, C22, and C23. In the embodiment, the first windings C11, C12, and C13 may be coupled to the first inverter 110 and the second windings C21, C22, and C23 may be coupled to the second inverter 120. [

5, the electric motor 130 is connected to a grid (not shown) for transmitting and receiving an AC voltage / current between the first windings C11, C12 and C13 and the corresponding second windings C21, C22 and C23 140, respectively.

It can be seen that the integrated charger 100 according to the embodiment of the present invention has battery packs 101, 102 having the same number of windings and power semiconductors but separated from each other as compared to that shown in Fig. 3 .

On the other hand, since the three phases operate on the same principle for each phase, a phase will be described as an example below. In the embodiment, when the motor 130 is operated in the drive mode, the output currents of the inverters can be controlled to have the same magnitude and opposite phases (ia1 = ia2). In the embodiment, when the motor 130 is operated in the battery charge / discharge mode, the output currents of the respective inverters can be controlled so as to be equal in magnitude and phase (ia1 = ia2). The grid-connected operation can be performed while preventing the rotation of the electric motor 130.

In the embodiment, although not shown in Fig. 5, a further breaker may be installed between the motor and the system. There is no circuit connection with the system when moving the electric car.

A crucial difference between a typical integrated charger and the integrated charger 100 of the present invention is that the grounded battery is used. However, the resulting application effects may be noticeable in the voltage and output currents applied to the motor windings.

FIG. 6 is a diagram illustrating an example of a motor winding voltage and current by a general integrated charger. The motor winding voltage and current shown in Fig. 6 are the result of the integrated charger of Fig. The integrated charger of Fig. 3 has an inverter voltage applied to the motor windings consisting of only three levels of ± Vdc and 0. In FIG. 6, the fundamental wave component of the voltage applied to the winding is 247.9 V, and RMS and THD are 221 V and 76.8%, respectively. 6 is an example of a current that can flow when such a winding voltage is applied. When the fundamental wave component is 39.6 A, RMS and THD are 28 A and 1.85%, respectively.

7 is a diagram illustrating an exemplary motor winding voltage and current of the integrated charger 100 according to an embodiment of the present invention. The winding voltage and output voltage shown in Fig. 7 are the result when using the same switching frequency and direct-current voltage in Fig.

Vdc, ±Vdc, ±

Vdc, ±

Vdc, 0의 9개 전압 레벨을 활용할 수 있다. 전압 출력 합성에 있어서 3배 더 많은 전압 레벨을 활용할 수 있기 때문에 고조파 특성이 도 6의 그것과 비교하여 눈에 띄게 향상시킬 수 있다. 그 결과, 도 7에서 권선에 인가되는 전압의 기본파 성분은 247.8V이고 RMS와 THD는 각각 190V와 42.6%이다. 또한, 도 7의 아래 파형에 보이듯 출력 전류는 기본파 성분이 39.6A일 때 RMS와 THD는 각각 28A와 1.3%이다.Since the integrated charger 100 according to the embodiment of the present invention has a separate battery structure,

Vdc, ± Vdc, ±

Vdc, ±

9 voltage levels of Vdc, 0 can be utilized. The harmonic characteristic can be improved remarkably compared with that of FIG. 6 since the voltage level of 3 times higher can be utilized in the voltage output synthesis. As a result, in FIG. 7, the fundamental wave component of the voltage applied to the winding is 247.8 V, and RMS and THD are 190 V and 42.6%, respectively. 7, when the fundamental wave component is 39.6 A, RMS and THD are 28 A and 1.3%, respectively.

Vdc로 일반적인 방식의 Vdc에 비해 dv/dt가 작아 전압 스트레스, 누설 전류나 EMI 측면에서도 이점을 갖는다.The integrated charger 100 according to the embodiment of the present invention can reduce the THD of the voltage and current by 44.5% and 29.7%, respectively, when compared with the conventional invention, and greatly improve the harmonic characteristic when the same fundamental wave component is output. In addition, the integrated charger 100 according to the embodiment of the present invention may be configured such that the voltage level interval

Vdc has a smaller dv / dt than Vdc in the conventional method, which is advantageous in terms of voltage stress, leakage current, and EMI.

Also, the integrated charger 100 according to the embodiment of the present invention has an advantage in the fundamental wave voltage output due to the separated grounded battery.

In a typical three-phase inverter, three harmonic components are used for improving the harmonic characteristics of the switching frequency by applying space vector pulse-width modulation (SVPWM) or maximizing the linear synthesis area.

FIG. 8 is a diagram illustrating an example of a pole voltage command and an output current when the SVPWM of a general integrated charger is used. The upper waveform in Fig. 8 shows an example in which a voltage command is generated by adding a third harmonic component to the fundamental wave for SVPWM. The lower waveform in Fig. 8 shows the output current in the conventional method when such a command is used. Since the conventional method uses one battery power, when a zero-sequence voltage such as the third harmonic is used for command synthesis, the corresponding harmonic current may flow. The output current of FIG. 8 shows that when the fundamental wave component is 39.5 A, the third harmonic component of 3.1 A corresponding to 7.9% is generated, and the lower harmonic characteristic is worse than that of FIG. 6. Since the main power transfer to the motor is via the fundamental wave component, these three harmonic components can lead to unnecessary loss and torque pulsation.

9 is a diagram illustrating an exemplary change in the frequency spectrum of the output current before and after using the SVPWM of the integrated charger 100 according to an embodiment of the present invention. The integrated charger 100 according to the embodiment of the present invention can use the separated battery power even if the third harmonic voltage is used for command synthesis, so that the third harmonic current can not flow.

In addition, since the SVPWM utilizing the third harmonic component can be applied, a further improved high-frequency characteristic appears at the same switching frequency. As shown in FIG. 9, the frequency spectrum of the output current before and after applying the SVPWM shows that the high frequency component near the switching frequency is reduced. As a result, through the application of SVPWM, the integrated charger 100 of the present invention can further reduce the THD from 1.3% to 1.2%.

In addition, the availability of three harmonic voltages is very important. 3 harmonic components are used in the voltage command synthesis, the voltage range in which the inverter linearly synthesizes can be increased by 15.5% compared to the case where the harmonic components are used in the voltage command synthesis. In an electric vehicle it is very important to produce as much output as possible at the same battery voltage and the same output current. Since the integrated charger 100 of the present invention can utilize the third harmonic component, the output of the inverter capable of outputting without harmonic distortion can be 15.5% larger than that of the conventional method.

As a result, the integrated charger 100 of the present invention can improve the harmonic characteristics at the same switching frequency as compared with the conventional one, and can output a larger output with the same inverter hardware.

The integrated charger 100 according to the embodiment of the present invention can increase the power conversion efficiency by enhancing the harmonic characteristic while incorporating the large-capacity charger of the electric vehicle itself. Also, since the integrated charger 100 according to the embodiment of the present invention is capable of bidirectional power conversion, it can contribute to activation of the V2G technology that links the electric vehicle to the system.

The integrated charger 100 according to the embodiment of the present invention is connected to the system through the motor winding by the inverter-motor integrated charger, and the inside of the electric vehicle improves the characteristics of the current flowing through the motor winding and the voltage applied thereto through the battery separation . In addition, the integrated charger 100 according to the embodiment of the present invention can enable the continuous operation of the electric vehicle even though the problem of one battery and power conversion device occurs due to the battery separation.

10 is a flow chart illustrating an exemplary method of operation of the integrated charger 100 according to an embodiment of the present invention. Referring to FIGS. 4 to 10, the integrated charger 100 may operate as follows.

A normal operable inverter may be selected (S110). Thereafter, it can be determined whether or not the system is connected (S120). If the grid connection is not established, the integrated charger 110 may operate in the motor drive mode (S130). On the other hand, if the system is linked, the integrated charger 110 may operate in the battery charge / discharge mode 140 (S140). Then, it is determined whether the shutdown has been performed (S150). If it has not been shut down, step S110 will proceed. Otherwise, if shut down, the operation of the integrated charger 100 will be terminated.

The steps and / or operations in accordance with the present invention may occur in different orders, in parallel, or concurrently in other embodiments for other epochs or the like, as may be understood by one of ordinary skill in the art .

Depending on the embodiment, some or all of the steps and / or operations may be performed on one or more non-transitory computer-readable media, including instructions, programs, interactive data structures, At least some of which may be implemented or performed using one or more processors. The one or more non-transitory computer-readable media can be, by way of example, software, firmware, hardware, and / or any combination thereof. Further, the functions of the "module" discussed herein may be implemented in software, firmware, hardware, and / or any combination thereof.

One or more non-transitory computer-readable media and / or means for implementing / performing one or more operations / steps / modules of embodiments of the present invention may be implemented as application-specific integrated circuits (ASICs), standard integrated circuits, But are not limited to, controllers that perform appropriate instructions, including microcontrollers, and / or embedded controllers, field-programmable gate arrays (FPGAs), complex programmable logic devices (CPLDs) .

An integrated charger for an electric vehicle according to an embodiment of the present invention includes: a first inverter connected to both ends of a first battery pack; A second inverter connected to both ends of the second battery pack; And three first windings connected to the first inverter and three second windings connected to the second inverter, and an AC voltage between the first windings and the second windings corresponding to the first windings, And an electric motor provided to the grid or provided from the grid.

In an embodiment, the ground terminal of the first battery pack and the ground terminal of the second battery pack may be separated from each other.

In the embodiment, the first and second inverters can be controlled so that the magnitudes of the output currents of the respective inverters in the motor drive mode are the same and have opposite phases.

In the embodiment, the first and second inverters can be controlled so that the magnitude and phase of the output current of each inverter are equal in the battery charge / discharge mode.

In an embodiment, a circuit breaker may further be provided between the electric motor and the grid.

In an embodiment, the first and second inverters may be controlled so that the output voltage of each of the first and second inverters has nine voltage levels.

In an embodiment, when controlling the first and second inverters, three high frequency components may be used for voltage command composition.

A method of operating an integrated charger for an electric vehicle according to an embodiment of the present invention includes: driving an electric motor using output voltages of a plurality of inverters generated by a battery separated in a motor driving mode; And stopping the electric motor by controlling the output current and the magnitude of each of the plurality of inverters equally in the battery charge / discharge mode.

In an embodiment, each of the plurality of inverter voltages may be a three-phase voltage.

In an embodiment, each of the plurality of inverters may be connected to the motor by three windings.

In an embodiment, the step of driving the motor may comprise the step of reversing the phase with the output magnitude of each of the plurality of inverters.

The above-described contents of the present invention are only specific examples for carrying out the invention. The present invention will include not only concrete and practical means themselves, but also technical ideas which are abstract and conceptual ideas that can be utilized as future technologies.

100: Integrated charger
101: First battery pack
102: Second battery pack
110: first inverter
120: Second inverter
130: electric motor
140: grid

Claims (9)

An integrated charger for an electric vehicle,
A plurality of battery packs serving as energy storage;
A plurality of inverters connected to the plurality of battery packs; And
And a plurality of windings connected to the plurality of inverters,
Wherein the plurality of windings are used for motor rotation or power system linkage. The method according to claim 1,
Wherein the plurality of battery packs are electrically disconnected from each other or connected to each other through an impedance. The method according to claim 1,
Further comprising a power semiconductor in which the plurality of inverters perform bi-directional power conversion between the plurality of battery packs and the plurality of windings. The method according to claim 1,
Wherein the plurality of windings is a conductor material electrically connected directly to the plurality of inverters to produce a rotating magnetic flux in a motor drive mode and to provide an electrical connection path between the inverter and the power system in a battery charge and discharge mode. The method according to any one of claims 1 to 4,
Said plurality of windings being connectable and separable between an integrated charger and a power system using a separate device. The method according to claim 1,
Wherein the power grid connection performs an operation of giving or receiving electrical energy between the battery and the power grid. The method according to claim 1,
Wherein the harmonic content rate of the voltage or current applied to the plurality of windings is controlled by the use of the plurality of inverters individually by controlling a configuration in which the plurality of battery packs are electrically disconnected from each other, The harmonic content of the voltage or current in the case of the integrated charger. 8. The method of claim 7,
Wherein the harmonic content rate is a ratio of all frequency components except for a fundamental frequency component actually seen in the plurality of windings with respect to a fundamental frequency component that is intended to be made through the plurality of inverters in the plurality of windings. The method according to claim 1,
Even if a failure occurs in a part of the plurality of inverters due to the configuration in which the plurality of battery packs are electrically disconnected from each other or interfere with the electric flow, Possible, integrated charger.

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