Electric vehicle and control method thereof

Abstract

The invention relates to an electric vehicle and a control method thereof. The electric vehicle includes: a power conversion device configured to perform power conversion between a direct current (DC) voltage and an alternating current (AC) voltage through a switching operation according to a duty cycle; and a controller configured to determine a first phase value that varies according to a sign of an alternating current of the AC voltage based on a phase of the AC voltage during the unit period, and perform duty compensation during a duty compensation period determined based on the first phase value.

Description

Technical Field

[0001] The present disclosure relates to an electric vehicle and a control method thereof. Background Art

[0002] Recently, as environmental concerns have increased, the number of eco-friendly vehicles equipped with electric motors as a power source has increased. Eco-friendly vehicles are also called electric vehicles, and representative examples include hybrid electric vehicles (HEVs) and pure electric vehicles (EVs).

[0003] With the widespread use of vehicles powered by electricity, the demand for electricity has increased dramatically, necessitating the development of technologies to address this issue.

[0004] In addition, as a means of meeting electricity demand, attempts to utilize new and renewable energy sources such as wind power and solar power generation are increasing due to environmental trends that minimize environmental pollution. However, with new and renewable energy sources, supply is unstable, and therefore an energy storage device that can balance supply and demand is needed.

[0005] The battery of an electric vehicle with an electric motor as a driving source can be used as an energy storage device. In order for electric vehicles to perform this function, it is necessary to implement vehicle-to-grid (V2G) technology, which allows the power stored in the vehicle battery to be supplied to the grid. Unlike existing on-board chargers (OBCs), the concept of V2G is to connect rechargeable and environmentally friendly vehicles such as electric vehicles to the grid through a bidirectional OBC, and transmit the energy stored in the battery back to the grid, where the bidirectional OBC can not only receive power from the grid but also supply the vehicle's power to the grid. In this case, the vehicle plays the role of an energy storage system (ESS). Summary of the Invention

[0006] The present disclosure relates to an electric vehicle and a control method thereof. Specific embodiments relate to an electric vehicle and a control method thereof that can improve harmonic distortion caused by dead time during the process of supplying power from the vehicle to the power grid.

[0007] Therefore, the embodiments of the present disclosure take into account the problems in the art, and the exemplary embodiments of the present disclosure improve the harmonic distortion caused by dead time by compensating the duty cycle of power conversion according to the reactive power and active power required by the grid in the process of supplying power from the vehicle to the grid.

[0008] The embodiments of the present disclosure are not limited to the above-mentioned embodiments, and those skilled in the art will clearly understand other embodiments not mentioned from the following description.

[0009] According to an embodiment of the present disclosure, the above and other embodiments can be achieved by providing an electric vehicle, which includes: a power conversion device, configured to perform power conversion between a direct current (DC) voltage and an alternating current (AC) voltage through a switching operation according to a duty cycle; and a controller, configured to determine a first phase value of a sign change of an alternating current according to the AC voltage based on the phase of the AC voltage during a unit cycle, and perform duty cycle compensation during a duty cycle compensation period determined based on the first phase value.

[0010] For example, the power conversion device may be connected to the grid and the battery, and the controller may perform duty cycle compensation when the DC voltage of the battery is converted into an AC voltage by the power conversion device and supplied to the grid.

[0011] For example, the controller may include a phase-locked loop having the AC voltage as an input signal, and may determine the phase of the AC voltage based on an output signal of the phase-locked loop.

[0012] For example, the controller may determine the first phase value by applying a delayed / lagging phase value of the alternating current relative to the phase of the AC voltage to the second phase value of the sign change of the AC voltage.

[0013] For example, the power conversion device may perform power conversion based on an active power command and a reactive power command from a power grid, and the delayed / lag phase value may be determined based on the active power command and the reactive power command.

[0014] For example, the duty ratio compensation period may be a period during the unit cycle excluding a first range of first phase values ​​based on the phase of the alternating current.

[0015] For example, the first range may be determined considering the AC voltage and the current duty cycle of the power conversion device.

[0016] For example, the size of the first range may be proportional to the AC voltage and the current duty cycle.

[0017] For example, the controller may maintain the current duty cycle of the power conversion device during the first range.

[0018] For example, the controller may perform duty cycle compensation by applying a compensation duty cycle determined based on a dead time and a switching frequency of a switching operation according to a current sign of the alternating current to a current duty cycle of the power conversion device.

[0019] According to another embodiment of the present disclosure, a control method for an electric vehicle is provided, the method including: performing power conversion between a DC voltage and an AC voltage through a switching operation according to a duty cycle by a power conversion device; determining a first phase value according to a sign change of an alternating current of the AC voltage based on the phase of the AC voltage during a unit cycle; and performing duty cycle compensation during a duty cycle compensation period determined based on the first phase value.

[0020] For example, the duty cycle compensation may be performed when a DC voltage of a battery is converted into an AC voltage by a power conversion device connected to the grid and the battery and supplied to the grid.

[0021] For example, determining the first phase value may include determining the phase of the AC voltage based on an output signal of a phase locked loop having the AC voltage as an input signal.

[0022] For example, determining the first phase value may include determining the first phase value by applying a delayed / lagging phase value of the alternating current relative to the phase of the AC voltage to the second phase value of the sign change of the AC voltage.

[0023] For example, the power conversion device may perform power conversion based on an active power command and a reactive power command from a power grid, and the delayed / lag phase value may be determined based on the active power command and the reactive power command.

[0024] For example, the duty ratio compensation period may be a period during the unit cycle excluding a first range of first phase values ​​based on the phase of the alternating current.

[0025] For example, the first range may be determined considering the AC voltage and the current duty cycle of the power conversion device.

[0026] For example, the size of the first range may be proportional to the AC voltage and the current duty cycle.

[0027] For example, the method may further include maintaining a current duty cycle of the power conversion device during the first range.

[0028] For example, performing duty cycle compensation may include performing duty cycle compensation by applying a compensation duty cycle determined based on a dead time and a switching frequency of a switching operation to a current duty cycle of the power conversion device according to a current sign of the alternating current. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The above and other objects, features and other advantages of the embodiments of the present disclosure will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which:

[0030] Figure 1 is a diagram for describing the configuration of an electric vehicle according to an embodiment of the present disclosure;

[0031] Figure 2 is a diagram for describing a duty cycle compensation process performed by a controller of an electric vehicle according to an embodiment of the present disclosure; and

[0032] Figure 3 is a diagram for describing a control method of an electric vehicle according to an embodiment of the present disclosure. DETAILED DESCRIPTION

[0033] The specific structural and functional descriptions of the embodiments of the present disclosure disclosed in this specification or application are merely illustrative for the purpose of illustrating the embodiments according to the present disclosure, and the embodiments according to the present disclosure can be implemented in various forms and should not be understood as being limited to the embodiments described in this specification or application.

[0034] Since the embodiments of the present disclosure can be modified in various ways and have various forms, specific embodiments will be shown in the drawings and described in detail in the specification or application. However, this is not intended to limit the embodiments of the concepts of the present disclosure to the specific disclosed forms, but should be understood to include all changes, equivalents and alternatives included in the spirit and technical scope of the present disclosure.

[0035] Unless otherwise noted, all terms, including technical or scientific terms, have the same meaning as commonly understood by those skilled in the art to which this disclosure belongs. Common terms, such as those defined in dictionaries, should be interpreted as consistent with their meaning in the relevant art, depending on the context. Unless otherwise defined in this disclosure, these terms should not be interpreted in an idealistic or overly formal manner.

[0036] Hereinafter, the embodiments disclosed in this specification will be described in detail with reference to the accompanying drawings. However, the same or similar components will be assigned the same reference numerals, and redundant descriptions will be omitted.

[0037] In the following description of the embodiments, the term "preset" means that the value of the parameter is predetermined when the parameter is used in a process or algorithm. Depending on the embodiment, the value of the parameter can be set at the beginning of the process or algorithm, or can be set during the period of execution of the process or algorithm.

[0038] In the following description of the embodiments disclosed in this specification, when a detailed description of known functions and configurations incorporated herein may obscure the subject matter of the present disclosure, such description will be omitted. In addition, the accompanying drawings are provided only to facilitate understanding of the embodiments disclosed in this specification and do not limit the technical spirit disclosed herein, and include all changes, equivalents, and alternatives included in the spirit and scope of the present disclosure.

[0039] The terms "first" and / or "second" are used to describe various components, but these components are not limited by these terms. These terms are used to distinguish one component from another component.

[0040] When a component is “coupled” or “connected” to another component, it should be understood that although the component may be directly coupled or connected to another component, a third component may exist between the two components. When a component is “directly coupled” or “directly connected” to another component, it should be understood that there is no element between the two components.

[0041] Elements described in the singular are intended to include plural elements unless the context clearly indicates otherwise.

[0042] In this specification, it will be further understood that the terms “include” or “comprising” indicate the presence of the stated features, numbers, steps, operations, components, parts or combinations thereof, but do not exclude the presence or addition of one or more other features, numbers, steps, operations, components or combinations thereof.

[0043] In addition, the unit or control unit included in names such as motor control unit (MCU) and hybrid control unit (HCU) is merely a term widely used when naming a control device that controls a specific vehicle function and does not represent a general functional unit.

[0044] The controller may include a communication device for communicating with other controllers or sensors to control the functions of the controller, a memory for storing an operating system, logic instructions, input / output information, etc., and one or more processors for performing the determinations, calculations, and decisions required for the control functions.

[0045] According to an embodiment of the present disclosure, an electric vehicle and a control method thereof compensate for the duty cycle of power conversion according to the reactive power and active power required by the grid during power supply from the vehicle to the grid (vehicle-to-grid (V2G)), thereby improving harmonic distortion caused by dead time while meeting the range of active power and reactive power required by the grid.

[0046] During power conversion, multiple switching elements used in a power conversion device are turned on in complementary fashion. If these complementary switching elements are turned on simultaneously, they may be damaged. Therefore, dead time is implemented to prevent damage to these elements when they are turned on simultaneously, by providing a slight time difference between when these switching elements are turned on.

[0047] On the other hand, when dead time is applied, an error occurs between the command voltage and the output voltage, resulting in a decrease in the fundamental voltage in the output voltage, which may increase total harmonic distortion. Therefore, embodiments of the present disclosure improve the total harmonic distortion caused by dead time through duty cycle compensation to meet the power specifications required by the power grid.

[0048] In the following, we will first refer to Figure 1 A configuration of an electric vehicle according to an embodiment of the present disclosure is described.

[0049] Figure 1 is a diagram for describing the configuration of an electric vehicle according to an embodiment of the present disclosure.

[0050] Reference Figure 1 , the electric vehicle 10 according to an embodiment of the present disclosure may include a power conversion device 100, a controller 200, and a battery 300, and may be connected to a grid 20. However, Figure 1 While components relevant to the described embodiments are shown, an actual electric vehicle may be implemented by including more or fewer components.

[0051] First, the power conversion device 100 can be connected between the battery 300 and the grid 20 and can perform power conversion between DC voltage and AC voltage by switching operations according to the duty cycle. For example, the power conversion device 100 can charge the battery 300 by converting AC power from the grid 20 into DC voltage and transmitting the DC voltage to the battery 300. In addition, the power conversion device 100 can convert DC voltage into AC power and provide the AC power to the grid 20. That is, in one embodiment, the power conversion device 100 can perform V2G functions.

[0052] To this end, the power conversion apparatus 100 may include an inverter that performs conversion between an AC voltage and a DC voltage through a switching operation of a switching element, and a bidirectional DC-DC converter that steps up or steps down a DC voltage.

[0053] In the embodiment of the present disclosure, the controller 200 controls the power conversion device 100 , and in particular, may compensate and determine a duty cycle of a switching operation of the power conversion device 100 .

[0054] More specifically, the controller 200 may determine a first phase value according to a sign change of the alternating current of the AC voltage based on the phase during a unit cycle of the AC voltage applied to the power conversion device 100. Thereafter, the controller 200 may determine a duty cycle compensation period based on the determined first phase value and perform duty cycle compensation during the duty cycle compensation period.

[0055] In this case, the controller 200 can perform duty cycle compensation when the power conversion device 100 converts the DC voltage of the battery 300 into an AC voltage and supplies the AC voltage to the grid 20. That is, during V2G operation, the controller 200 can perform duty cycle compensation on the power conversion device 100. When supplying power to the grid 20, it may be necessary to meet specifications regarding the range of active power and reactive power, as well as total harmonic distortion. During V2G operation, duty cycle compensation can be used to meet the power specifications required for the power supplied to the grid 20.

[0056] To perform such duty cycle compensation, the controller 200 may include a phase locked loop 210 , a delay / lag phase value determination unit 220 , a compensation period determination unit 230 , and a duty cycle controller 240 .

[0057] First, before performing duty cycle compensation, the controller 200 determines a duty cycle compensation period during which the duty cycle will be compensated. To this end, the controller 200 may determine the phase θ of the AC voltage based on an output signal of a phase locked loop 210 having the AC voltage Vac as an input signal. Vac The phase-locked loop 210 can obtain the AC voltage Vac from the power grid 20 as an input signal, and then outputs a phase θ corresponding to the input AC voltage Vac through processes such as d and q conversion, proportional integral (PI) control and voltage range limitation. Vac .

[0058] The delay / lag phase value determination unit 220 determines the delay / lag phase value of the AC current relative to the AC voltage phase, and can thereby obtain the reactive power command Q and the active power command P of the grid 20. For example, the delay / lag phase value θ Ishift It can be determined using the following equation 1.

[0059] Equation 1 :

[0060] In this case, the reactive power command Q and the active power command P of the grid 20 may be transmitted to the delay / lag phase value determination unit 220 via a vehicle charge management system (VCMS). Such a vehicle charge management system may be provided on the electric vehicle 10 side or in a charger connecting the grid 20 and the electric vehicle 10.

[0061] The power conversion device 100 performs power conversion based on the active power command P and the reactive power command Q from the power grid 20, and the delay / lag phase value determination unit 220 can determine the delay / lag phase value θ of the phase of the AC current relative to the AC voltage based on the active power command P and the reactive power command Q. Ishift .

[0062] The compensation period determination unit 230 may be based on the phase θ during a unit cycle of the AC voltage as the output signal of the phase locked loop 210. Vac A first phase value according to a sign change of the alternating current of the AC voltage is determined, and a duty ratio compensation period is determined based on the determined first phase value.

[0063] More specifically, the compensation period determination unit 230 may first determine the phase θ during a unit cycle of the AC voltage as the output signal of the phase locked loop 210. Vac Determine the second phase value of the sign change of the AC voltage, and use the delay / lag phase value θ determined by the delay / lag phase value determination unit 220 to determine the second phase value of the AC voltage. Ishift The first phase value is applied to the second phase value to determine a change in sign of the alternating current.

[0064] That is, the first phase value may refer to the zero-crossing point where the AC current value reaches "0," and the second phase value may refer to the zero-crossing point where the AC voltage value reaches "0." Therefore, determining the compensation period based on the first and second phase values ​​can be understood as detecting the zero-crossing point of the AC power from the zero-crossing point of the AC voltage, and determining the compensation period based on the zero-crossing point of the AC power.

[0065] Once the first phase value is determined, compensation period determination unit 230 may determine a first range based on the determined first phase value and determine a period during the unit cycle that does not include the first range as the duty cycle compensation period. Here, the first range includes a period during which the AC current value is "0." This period is a period during which the fundamental voltage does not drop compared to the command voltage due to the dead time, and therefore is not included in the duty cycle compensation period.

[0066] In this case, the first range may be determined considering the AC voltage Vac and the current duty cycle of the power conversion apparatus 100. More specifically, the first range may be based on the first phase value, and its size may be determined to be proportional to the AC voltage Vac and the current duty cycle.

[0067] When the compensation period is determined, the duty cycle controller 240 may transmit a final duty cycle obtained by applying the compensation duty cycle to the current duty cycle during the compensation period to the power conversion device 100 and control the power conversion device 100 to perform power conversion according to the final duty cycle.

[0068] In this case, the compensation duty cycle can be determined based on the dead time and the switching frequency of the switching operation. For example, the product of the dead time and the switching frequency can be determined as the compensation duty cycle. In addition, the duty cycle controller 240 can apply the compensation duty cycle to the current duty cycle according to the current sign of the alternating current. For example, the duty cycle controller 240 can perform duty cycle compensation by adding the compensation duty cycle to the current duty cycle when the current sign of the alternating current is (+), and by subtracting the compensation duty cycle from the current duty cycle when the current sign of the alternating current is (-).

[0069] On the other hand, the duty cycle controller 240 may maintain the current duty cycle of the power conversion device 100 within the first range that does not correspond to the duty cycle compensation period without performing duty cycle compensation. In this case, the current duty cycle is used as the final duty cycle to determine the switching operation of the power conversion device 100.

[0070] In the following, reference will be made to Figure 2 The duty cycle compensation process is described in more detail.

[0071] Figure 2 is a diagram for describing a duty cycle compensation process performed by a controller of an electric vehicle according to an embodiment of the present disclosure.

[0072] Figure 2 The AC voltage Vac and the AC current Iac and the compensation duty ratio D are shown when the unit cycle 2π is repeated. comp Graph of the behavior.

[0073] First, the controller 200 determines the phase θ of the AC voltage Vac based on the AC voltage Vac of the power grid 20. vac The controller 200 determines the second phase values ​​π / 2 and 3π / 2 of the sign change of the AC voltage Vac. Then, the controller 200 determines the second phase values ​​π / 2 and 3π / 2 of the sign change of the AC voltage Vac. Ishift The first phase value π / 2-θ of the alternating current is determined from the determined second phase values ​​π / 2 and 3π / 2. Ishift and 3π / 2-θ Ishift .

[0074] Determine the first phase value π / 2-θ Ishift and 3π / 2-θ Ishift As a standard for the duty cycle compensation period. More specifically, the controller 200 may be based on the first phase value π / 2-θ Ishift and 3π / 2-θ Ishift Determine the first range (π / 2-θ Ishift )-α to (π / 2-θ Ishift )+α and (3π / 2-θ Ishift)-α to (3π / 2-θ Ishift )+α, and will be different from the first range (π / 2-θ Ishift )-α to (π / 2-θ Ishift )+α and (3π / 2-θ Ishift )-α to (3π / 2-θ Ishift )+α is determined as the duty cycle compensation period.

[0075] In this case, the size 2α of the first range may be proportional to the size of the AC voltage Vac and the current duty cycle, and may be determined by the following Equation 2, for example.

[0076] Equation 2 :α=β*Vac*Duty

[0077] Here, α is a factor that determines the size of the first range, Vac is the size of the AC voltage, Duty represents the current duty cycle, and β represents a proportional constant between the AC voltage and the current duty cycle.

[0078] When the compensation period is determined as above, the controller 200 adjusts the compensation duty ratio D according to the current sign of the AC current during the compensation period. comp The duty cycle compensation is performed by reflecting it in the current duty cycle. Therefore, in the period when the sign of the AC current is (+), the duty cycle D is compensated. comp can have a positive value, and in the period when the sign of the AC current is (-), the compensation duty cycle D comp In addition, since duty cycle compensation is not performed in the first range that does not correspond to the compensation period, the compensation duty cycle D is comp The value of can be "0".

[0079] Hereinafter, a control method of an electric vehicle according to an embodiment will be described using a flowchart.

[0080] Figure 3 is a diagram for describing a control method of an electric vehicle according to an embodiment of the present disclosure.

[0081] Reference Figure 3 First, the controller 200 can obtain the phase θ of the AC voltage through the output of the phase-locked loop 210. vac (S311), and obtain the delayed / lag phase value θ based on the active power command P and the reactive power command Q Ishift (S312).

[0082] The controller 200 can obtain the phase θ of the AC voltage based on the vac and the delayed / lag phase value θ Ishift Determine the first range (π / 2-θ Ishift)-α to (π / 2-θ Ishift )+α and (3π / 2-θ Ishift )-α to (3π / 2-θ Ishift )+α, and determine the phase θ of the AC voltage vac Is it included in the first range (π / 2-θ Ishift )-α to (π / 2-θ Ishift )+α) and (3π / 2-θ Ishift )-α to (3π / 2-θ Ishift )+α (S313) to determine whether to perform duty cycle compensation. For example, if the phase θ of the AC voltage vac Included in the first range (π / 2-θ Ishift )-α to (π / 2-θ Ishift )+α and (3π / 2-θ Ishift )-α to (3π / 2-θ Ishift )+α (Yes in S313), the controller 200 may determine that it is not a compensation period. If the phase θ of the AC voltage vac Not included in the first range (π / 2-θ Ishift )-α to (π / 2-θ Ishift )+α and (3π / 2-θ Ishift )-α to (3π / 2-θ Ishift )+α (No in S313), the controller 200 may determine that it corresponds to the compensation period (S317).

[0083] If it is determined that it is not the compensation period (S314), the controller 200 compensates the duty cycle D comp The current duty ratio Duty is determined to be “0” ( S315 ), and the power conversion device 100 is controlled using the current duty ratio Duty as the final duty ratio Duty′ ( S316 ).

[0084] On the other hand, in the compensation period (S317), the controller 200 calculates the compensation period based on the dead time T dead and the switching frequency fsw determine the compensation duty cycle D comp (S318), and by the AC current I ac The current sign (S319) will compensate the duty cycle D comp The duty cycle compensation is performed by reflecting it in the current duty cycle Duty.

[0085] For example, if the AC current I ac If the current sign is positive (“Yes” in S319), the controller 200 can compensate the duty cycle D comp Added to the current duty cycle Duty to perform duty cycle compensation (S320), if the AC current I acIf the current sign is negative ("No" in S319), the controller 200 can compensate the duty cycle D by subtracting the current duty cycle Duty from the current duty cycle Duty. comp To perform duty cycle compensation (S321).

[0086] After the duty cycle compensation, the controller 200 controls the power conversion apparatus 100 using a final duty cycle Duty′ determined by the duty cycle compensation.

[0087] According to various embodiments of the present disclosure described above, during the process of supplying power from a vehicle to a power grid, duty cycle compensation of power conversion can be used to improve harmonic distortion while meeting the range of reactive power and active power required by the power grid.

[0088] In addition, duty cycle compensation can be performed through a phase-locked loop to ensure the above-mentioned harmonic distortion improvement performance without additional hardware, and to expand the applicable power factor range to improve robustness in the application process.

[0089] Effects obtainable from the embodiments of the present disclosure are not limited to the above-mentioned effects, and those skilled in the art can clearly understand other effects not mentioned from the description herein.

[0090] As apparent from the above description, embodiments of the present disclosure provide an electric vehicle and a control method thereof.

[0091] Although the preferred embodiments of the present disclosure have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the disclosure as disclosed in the accompanying claims.

Claims

1. An electric vehicle comprising: a power conversion device that performs power conversion between a direct current voltage (DC voltage) and an alternating current voltage (AC voltage) by switching operations according to a duty cycle; as well as A controller determines a first phase value according to which a sign of an alternating current of the AC voltage changes based on a phase of the AC voltage during a unit cycle, and performs duty ratio compensation during a duty ratio compensation period determined based on the first phase value.

2. The electric vehicle according to claim 1, wherein: The controller includes a phase-locked loop having the AC voltage as an input signal, and determines a phase of the AC voltage based on an output signal of the phase-locked loop.

3. The electric vehicle according to claim 1, wherein: The power conversion device is connected to a grid and a battery, and the controller performs the duty ratio compensation when a DC voltage of the battery is converted into the AC voltage by the power conversion device and supplied to the grid.

4. The electric vehicle according to claim 3, wherein: The controller determines the first phase value by applying a delayed / lagging phase value of the alternating current with respect to the phase of the AC voltage to a second phase value of the AC voltage whose sign is changed.

5. The electric vehicle according to claim 4, wherein: The power conversion device performs the power conversion based on an active power command and a reactive power command from the power grid, and the delayed / lag phase value is determined based on the active power command and the reactive power command.

6. The electric vehicle according to claim 1, wherein The duty ratio compensation period is a period during the unit cycle excluding a first range of the first phase value based on the phase of the alternating current.

7. The electric vehicle according to claim 6, wherein: The first range is determined further considering the AC voltage and a current duty cycle of the power conversion device.

8. The electric vehicle according to claim 7, wherein: The size of the first range is proportional to the AC voltage and the current duty cycle.

9. The electric vehicle according to claim 6, wherein: The controller maintains a current duty cycle of the power conversion device during the first range.

10. The electric vehicle according to claim 1, wherein The controller performs the duty cycle compensation by applying a compensation duty cycle determined based on a dead time and a switching frequency of the switching operation according to a current sign of the alternating current to a current duty cycle of the power conversion device.

11. A method for controlling an electric vehicle, comprising: Performing power conversion between a direct current voltage, i.e., a DC voltage, and an alternating current voltage, i.e., an AC voltage, by switching operations according to a duty cycle; determining a first phase value according to a sign change of an alternating current of the AC voltage based on a phase of the AC voltage during a unit period; as well as Duty cycle compensation is performed during a duty cycle compensation period determined based on the first phase value.

12. The method according to claim 11, wherein Determining a first phase value includes determining a phase of the AC voltage based on an output signal of a phase locked loop having the AC voltage as an input signal.

13. The method according to claim 11, wherein Duty cycle compensation is performed when a DC voltage of the battery is converted into the AC voltage by a power conversion device connected to the grid and the battery and supplied to the grid.

14. The method according to claim 13, wherein: Determining a first phase value includes determining the first phase value by applying a delayed / lagging phase value of the alternating current relative to the phase of the AC voltage to a second phase value of the change in sign of the AC voltage.

15. The method according to claim 14, wherein Performing power conversion includes performing the power conversion based on an active power command and a reactive power command from the grid, and the delayed / lag phase value is determined based on the active power command and the reactive power command.

16. The method according to claim 11, wherein The duty ratio compensation period is a period during the unit cycle excluding a first range of the first phase value based on the phase of the alternating current.

17. The method according to claim 16, wherein The first range is determined taking into account the AC voltage and a current duty cycle of the power conversion device.

18. The method according to claim 17, wherein: The size of the first range is proportional to the AC voltage and the current duty cycle.

19. The method of claim 16, further comprising maintaining a current duty cycle of a power conversion device during the first range.

20. The method according to claim 11, wherein Performing duty cycle compensation includes performing the duty cycle compensation by applying a compensation duty cycle determined based on a dead time and a switching frequency of the switching operation to a current duty cycle of a power conversion device according to a current sign of the alternating current.

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