Electric vehicle equipped with engine and control method thereof

Abstract

The invention relates to an electric vehicle equipped with an engine and a control method thereof. The electric vehicle may include a battery, an engine, an electric machine configured to generate power by receiving mechanical energy from the engine, a power converter configured to rectify alternating current (AC) power generated by the electric machine to direct current (DC) power, convert a voltage of the rectified direct current to a charging voltage, and control the charging voltage. And a controller configured to determine a voltage conversion duty ratio based on a voltage of the rectified direct current and a voltage of the battery, in which the power converter converts the voltage of the rectified direct current into a charging voltage based on a control signal corresponding to the voltage conversion duty ratio.

Description

Technical Field

[0001] This application relates to an electrified vehicle capable of extending its driving range using a generator engine, and a method for driving control thereof. Background Technology

[0002] With increasing environmental awareness, there is a growing number of environmentally friendly vehicles equipped with electric motors as their power source. These environmentally friendly vehicles are also known as electrified vehicles, with representative examples being hybrid electric vehicles (HEVs) and electric vehicles (EVs).

[0003] Electric vehicles (EVs) operate using an electric motor (e.g., solely) and are powered by electricity supplied by a battery. However, EVs may have issues with limited (e.g., relatively) driving range and long charging times.

[0004] Therefore, range-extended electric vehicles (EREVs) are considered, which incorporate a generator engine to increase driving range. Unlike EVs, EREVs can include an engine and motor to generate electricity to charge the battery, and EREVs can utilize an inverter to supply the battery with the electricity generated during regenerative braking.

[0005] This background section is intended to aid in understanding this application and should not be construed as prior art. Summary of the Invention

[0006] This application aims to provide an electrified vehicle capable of stably converting the voltage range of the generated electricity according to (e.g., optimal) engine operating conditions.

[0007] Furthermore, this application aims to provide an electrified vehicle in which the voltage control of the generated electricity is easy and highly stable.

[0008] This application is not limited to the foregoing, and other purposes not described herein may be understood from the description herein.

[0009] This document provides an electrified vehicle. In an exemplary embodiment, the electrified vehicle may include a battery, an engine, a motor, and a power converter. The motor is configured to generate electricity by receiving mechanical energy from the engine. The power converter is configured to rectify the alternating current (AC) generated by the motor into direct current (DC), convert the voltage of the rectified DC into a charging voltage, and output the converted voltage to the battery. The electrified vehicle may further include a controller configured to determine a voltage conversion duty cycle based on the voltage of the rectified DC and the voltage of the battery. The power converter may convert the voltage of the rectified DC into a charging voltage based on a control signal corresponding to the voltage conversion duty cycle.

[0010] According to an exemplary embodiment, the power converter may include a buck-boost converter configured to boost or buck the charging voltage based on the voltage conversion duty cycle.

[0011] According to an exemplary embodiment, the buck-boost converter may include a switch disposed at an input configured to receive rectified DC power, the switch being controlled to be turned on and off based on the control signal.

[0012] According to an exemplary embodiment, the switch located at the input terminal may include a plurality of switching elements connected in series.

[0013] According to an exemplary embodiment, the motor may include a three-phase motor, and the power converter may include a three-phase rectifier configured to convert the three-phase alternating current generated by the motor into direct current.

[0014] According to an exemplary embodiment, the controller can determine the charging voltage based on the battery voltage, and determine the voltage conversion duty cycle based on the charging voltage and the voltage of the rectified DC power.

[0015] According to an exemplary embodiment, the controller can further determine whether the battery voltage is lower than a predetermined reference voltage, and control engine operation based on the battery voltage being lower than the reference voltage.

[0016] According to an exemplary implementation, the engine can operate in a predetermined drive mode based on the engine's energy efficiency.

[0017] This application provides a method for controlling an electrified vehicle. In an exemplary embodiment, the method may include: operating an engine by a controller; generating electricity by a motor by receiving mechanical energy from the engine; rectifying the alternating current (AC) generated by the motor into direct current (DC) by a power converter; and determining a voltage conversion duty cycle by the controller based on the voltage of the rectified DC and the voltage of the battery, wherein the power converter may convert the voltage of the rectified DC into a charging voltage based on a control signal corresponding to the voltage conversion duty cycle.

[0018] According to an exemplary embodiment, the power converter may include a buck-boost converter configured to boost or buck the charging voltage based on the voltage conversion duty cycle.

[0019] According to an exemplary embodiment, the buck-boost converter may include a switch disposed at an input configured to receive rectified DC power, the switch being controlled to be turned on and off based on the control signal.

[0020] According to an exemplary embodiment, the switch located at the input terminal may include a plurality of switching elements connected in series.

[0021] According to an exemplary embodiment, the motor may include a three-phase motor, and the power converter may include a three-phase rectifier configured to convert the three-phase alternating current generated by the motor into direct current.

[0022] According to an exemplary implementation, determining the voltage conversion duty cycle may include: the controller determining the charging voltage based on the battery voltage, and determining the voltage conversion duty cycle based on the charging voltage and the voltage of the rectified DC power.

[0023] According to an exemplary embodiment, the method may further include: determining whether the battery voltage is lower than a predetermined reference voltage; and operating the engine based on the battery voltage being lower than the reference voltage.

[0024] According to an exemplary implementation, the engine can operate in a predetermined drive mode based on the engine's energy efficiency.

[0025] According to the exemplary embodiments of this application described herein, it may be advantageous to provide an electrified vehicle capable of converting the voltage range of generated electricity according to (e.g., optimally) engine operating conditions (e.g., stably).

[0026] It would also be beneficial to provide an electrified vehicle that offers easy and highly stable voltage control for the generated electricity.

[0027] This application is not limited to the foregoing content, and other uses and details not described herein can be understood from the description herein. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the configuration of the EREV according to the implementation scheme of this application;

[0029] Figure 2 This is a schematic diagram illustrating the process of charging batteries with electricity generated by driving a generator engine;

[0030] Figure 3 This is a schematic diagram of the control system configuration of an EREV according to an embodiment of this application;

[0031] Figure 4 This is a schematic diagram of the configuration of a power converter according to an embodiment of this application;

[0032] Figure 5 It is a voltage curve of the power converter inside the embodiment of this application;

[0033] Figure 6It is a graph of the duty cycle of the buck-boost converter according to the embodiment of this application;

[0034] Figure 7 This is a flowchart illustrating the operation of a VCU controlling battery charging using a generator engine according to an embodiment of this application. Detailed Implementation

[0035] The structural or functional descriptions of the embodiments disclosed herein are illustrative examples intended to describe embodiments of this application, and embodiments of this application may be provided in various forms (e.g., implementations) and should not be construed as limited to the embodiments described herein.

[0036] Although exemplary embodiments are shown in the accompanying drawings and described in detail herein, embodiments of this application may be modified in various ways and may take different forms.

[0037] Unless otherwise defined, all terms used herein, including technical or scientific terms, may have the same meaning as commonly understood. Unless explicitly defined in this specification, terms herein should be interpreted in a manner similar to or consistent with their meaning in the context of the relevant field.

[0038] The following description of exemplary embodiments disclosed in this specification is provided with reference to the accompanying drawings, in which similar or identical components are assigned similar or identical reference numerals, and redundant descriptions thereof are omitted.

[0039] In the description of the implementation scheme, the term "predetermined" means (e.g., implies) that the value of a parameter can be established in advance when it is used in a process or algorithm. The value of the parameter can be set at the beginning of the process or algorithm according to the implementation scheme, or it can be established during the execution of the process or algorithm according to the implementation scheme.

[0040] As used in this article, the suffixes “module” and “unit” can be used interchangeably, but they may not have a distinguishing meaning or function.

[0041] Furthermore, if detailed descriptions of known techniques related to the embodiments disclosed in this specification obscure the subject matter of the disclosed embodiments, such detailed descriptions may be omitted. Additionally, the accompanying drawings provide an understanding of the embodiments disclosed in this specification and do not limit the scope of this disclosure. Embodiments herein may include (e.g., all) modified, equivalent, and alternative embodiments within the scope of this application.

[0042] As used herein, terms including ordinal numbers such as “first” and “second” can be used to describe various components without limiting the scope of the components. These terms can be used to distinguish one component from another.

[0043] When a component is described as "connected to" or "linked to" another component, the component may be (for example, directly) connected to or linked to the other component, or there may be intermediate components. Conversely, when a component is described as "directly connected to" or "directly linked to" another component, there may be no intermediate components.

[0044] Unless the context otherwise indicates, the singular form is intended to include the plural form as well.

[0045] When used in this specification, the terms "comprising" or "having" may mean the presence of the said feature, value, step, operation, component, element or combination thereof, but do not exclude the presence or addition of one or more other features, values, steps, operations, components, elements or combinations thereof.

[0046] Furthermore, the terms “unit” or “control unit” included in the name of a motor control unit (MCU) or vehicle control unit (VCU) may be used to describe a controller responsible for (e.g., specific) functions of the vehicle, rather than indicating a general-purpose functional unit.

[0047] The electrified vehicle in this article can be an EREV, which increases its driving range by adding an engine and a motor to generate electricity to charge the battery.

[0048] Figure 1 This is a schematic diagram of the configuration of the EREV according to the implementation scheme of this application.

[0049] Reference Figure 1 The EREV may include a battery 110, an inverter 120, a drive motor 130, a charging device 140, a generator engine 150, a generator motor 160, and a power converter 170.

[0050] Battery 110 can store electricity and supply power to inverter 120 and drive motor 130 for driving EREV.

[0051] Inverter 120, which includes multiple switches, can convert power output from battery 110 into a form suitable for driving motor 130. For example, inverter 120 can take direct current (DC) power output from battery 110 and convert the DC power into three-phase alternating current (AC) power for driving motor 130.

[0052] The drive motor 130 can drive the EREV based on the power received from the inverter.

[0053] However, the inverter 120 and drive motor 130 may not (e.g., only) be responsible for driving the vehicle. For example, during deceleration, the inverter 120 and drive motor 130 can perform regenerative braking by converting the driving force of the wheels into electrical energy to charge the battery 110. In an exemplary embodiment, during regenerative braking, the drive motor 130 can convert the driving force of the wheels into alternating current, and the inverter 120 can convert the generated alternating current into direct current for charging the battery 110.

[0054] The charging device 140 is connected to an external power source and can charge the battery 110 based on the power received from the external power source.

[0055] The generator engine 150 generates power by burning fuel. The power generated by the generator engine 150 is used (e.g., only) to generate electricity to charge the battery 110 and is not transmitted to the vehicle's wheels to directly drive the EREV. Furthermore, the generator engine 150 can operate in a predetermined driving mode based on its energy efficiency. For example, the predetermined driving mode could be a mode that drives the generator engine 150 at its optimal efficiency point.

[0056] The generator motor 160 can convert the power received from the generator engine 150 into alternating current. The generator motor 160 may include a three-phase motor and may be directly connected to the engine shaft of the generator engine 150 to rotate together.

[0057] The power converter 170 rectifies the alternating current (AC) generated by the generator motor 160 into direct current (DC), and converts the voltage of the rectified DC current into a charging voltage for charging the battery 110. To achieve this, the power converter 170 may include a rectifier that converts the AC current generated by the generator motor 160 into DC current, and a buck-boost converter that boosts or bucks the charging voltage for charging the battery 110.

[0058] Figure 2 This is a schematic diagram illustrating the process of charging batteries with electricity generated by driving a generator engine.

[0059] Figure 2 The diagram illustrates the speed control mode of the generator engine 150 and the relationship between the charging current magnitude and the duty cycle during battery charging voltage control for charging battery 110.

[0060] When controlling the charging voltage of the battery 110, the generator engine 150 can consider the optimal operating point and operate in a predetermined drive mode. The generator engine 150 can rotate at a constant speed corresponding to its optimal operating point.

[0061] The generator motor 160 is configured as a three-phase motor, converting the power generated by the generator engine 150 into electrical energy. The load of the generator motor 160 is controlled by the generator engine 150, which operates at a constant speed, and the torque control of the generator motor 160 based on variable resistance does not need to be performed independently.

[0062] The rectifier of the power converter 170 rectifies the generated alternating current into direct current, and the buck-boost converter can convert the voltage of the rectified direct current into a charging voltage for charging the battery 110.

[0063] In an exemplary embodiment, when the voltage conversion duty cycle of the control signal received by the buck-boost converter decreases, the magnitude of the charging voltage and charging current output from the buck-boost converter decreases; conversely, when the voltage conversion duty cycle increases, the magnitude of the charging voltage and charging current output from the buck-boost converter increases. A power converter 170 including such a rectifier and buck-boost converter may be advantageous in terms of packaging structure and cost (e.g., compared to a six-switch converter including six switches).

[0064] Figure 3 This is a schematic diagram of the control system configuration of an EREV according to an embodiment of this application.

[0065] Reference Figure 3 In the EREV, the inverter 120 and drive motor 130 can be controlled by drive motor controller 230, the generator engine 150 can be controlled by engine controller 250, and the generator motor 160 and power converter 170 can be controlled by generator motor controller 260.

[0066] Each controller is connected to the vehicle control unit (VCU) 210, which controls (e.g., the entire) powertrain system as a higher-level controller, providing the VCU 210 with (e.g., necessary) information to determine the operation and shutdown of the engine or motor, or performing operations based on control commands received from the VCU 210.

[0067] The drive motor controller 230 can control the gate drive unit using a pulse width modulation (PWM) control signal based on the motor angle, phase voltage, phase current, and (e.g., required) torque of the drive motor 130, thereby (e.g., enabling) the gate drive unit to correspondingly control the inverter 120 that drives the drive motor 130.

[0068] The generator controller 260 is connected to the power converter 170 and can control the charging voltage of the battery 110. For example, the generator controller 260 determines the duty cycle of the control signal output to the buck-boost converter of the power converter 170, and outputs the control signal to the buck-boost converter based on the determined duty cycle to control the charging voltage output to the battery 110.

[0069] The connection between the control unit and the functions / categories of each controller is exemplary and may not be limited to names. For example, the VCU210 may be configured (e.g., implemented) so that the corresponding functions are provided by any of the other controllers, or these functions may be distributed among two or more other controllers.

[0070] Figure 4 This is a schematic diagram of the configuration of a power converter according to an embodiment of this application.

[0071] Reference Figure 4 The power converter 170 may include a three-phase rectifier 171 and a step-up / step-down converter 172. The three-phase rectifier 171 rectifies the three-phase AC power generated from the generator engine 150 and the generator motor 160 into DC power. The step-up / step-down converter 172 converts the voltage of the rectified DC power into a charging voltage for output to the battery 110.

[0072] The three-phase rectifier 171 is a device for converting alternating current (AC) to direct current (DC) and may include a plurality of diodes D11, D12, D21, D22, D31, and D32, as well as a capacitor C1. In an exemplary embodiment, the three-phase rectifier may include an a-phase input terminal 11, a b-phase input terminal 21, and a c-phase input terminal 31 that respectively receive power from phases a, b, and c.

[0073] In an exemplary embodiment, the first to sixth diodes D11, D12, D21, D22, D31, and D32 can form branches corresponding to each phase of the generated three-phase alternating current. For example, the first branch can consist of the first diode D11 and the second diode D12 connected to the a-phase input terminal 11, the second branch can consist of the third diode D21 and the fourth diode D22 connected to the b-phase input terminal 21, and the third branch can consist of the fifth diode D31 and the sixth diode D32 connected to the c-phase input terminal 31.

[0074] Furthermore, the first capacitor C1 can stabilize the voltage rectified by the three-phase rectifier 171 and reduce the ripple voltage of the rectified DC power. The voltage measured across the first capacitor C1 will be referred to herein as the rectified voltage V1 of the three-phase rectifier 171.

[0075] Figure 5 It is a voltage curve of the power converter inside the embodiment of this application.

[0076] Reference Figure 5 The horizontal axis represents time, and the vertical axis shows the curves from top to bottom representing the phase voltage, line voltage, rectified voltage with a phase delay angle of 0 degrees, and rectified voltage with a phase delay angle of 30 degrees.

[0077] The phase voltage graph shows the phase voltages corresponding to each phase (e.g., phase a, phase b, and phase c) of the three-phase rectifier 171.

[0078] In an exemplary embodiment, the phase voltage curve shows the time-varying voltages of phase a, phase b, and phase c as periodic fluctuations of an AC waveform, with each phase voltage changing phase by 120 degrees.

[0079] In addition, the line voltage graph shows the line voltages between the corresponding first to third input terminals 11, 21 and 31, namely, the line voltage Vab between the first input terminal 11 and the second input terminal 21, the line voltage Vbc between the second input terminal 21 and the third input terminal 31, and the line voltage Vca between the third input terminal 31 and the first input terminal 11.

[0080] Based on the inductance and capacitance characteristics of the generator engine 150, generator motor 160, and three-phase rectifier 171, the rectified voltage V1 output from the three-phase rectifier 171 may exhibit a delay angle α.

[0081] When viewing the graph of the rectified voltage V1 with a delay angle α of 0 degrees, the rectified voltage V1 is (e.g., relatively) stable with minimal ripple when the delay angle α is 0 degrees.

[0082] Conversely, when the delay angle α is 30 degrees, the curve of the rectified voltage V1 shows that the voltage of each phase is delayed by 30 degrees, resulting in increased ripple of the rectified voltage V1 and reduced effective output power.

[0083] The three-phase AC voltage of the generator 160 is rectified into DC voltage using a three-phase rectifier 171, and phase shifting is performed (e.g., implemented) based on the current magnitude to improve the power factor and control harmonic characteristics. For example, VCU210 can control the voltage conversion duty cycle of the signal output to the buck-boost converter 172 based on the magnitude of the rectified voltage V1, which reflects the delay angle, thereby maximizing the conversion efficiency of the power charged into the battery and providing a stable DC power supply.

[0084] Refer again Figure 4 The buck-boost converter 172 is a device that converts rectified voltage V1 into charging voltage V2 based on a control signal corresponding to the voltage conversion duty cycle, and may include a switch S, an inductor L2, a diode D2, and a second capacitor C2.

[0085] A six-switch converter that converts power by controlling each of the six switches can regulate the magnitude of the regenerative torque of the generator motor based on the signal output to each switch, thereby regulating the power and voltage charged to the battery. In contrast, a power converter 170 that converts power generated by a three-phase rectifier 171 and a buck-boost converter 172 can regulate the magnitude of the voltage of the power output to the battery 110 by controlling the voltage conversion duty cycle of the control signal output to the buck-boost converter 172.

[0086] In an exemplary embodiment, since a relatively high voltage can be applied to the switch S, the switch S can be composed of power devices (e.g., IGBTs or MOSFETs) with relatively high rated voltages. In an exemplary embodiment, the switch S may include multiple switching elements connected in series to reduce the magnitude of the voltage applied to each element.

[0087] In an exemplary embodiment, a control signal corresponding to the voltage conversion duty cycle is applied to switch S, such that the output charging voltage V2 can be boosted or bucked according to the determined voltage conversion duty cycle. When switch S comprises multiple switching elements, the control signal corresponding to the voltage conversion duty cycle can be applied to the gate of each switching element.

[0088] The voltage conversion duty cycle can be determined based on the rectified DC voltage V1 and the charging voltage V2 used to charge battery 110. More specifically, the voltage conversion duty cycle D can be determined by substituting the rectified voltage V1 and the charging voltage V2 into the following equation.

[0089] Equation

[0090]

[0091] In the equation, V1 is the rectified voltage, V2 is the charging voltage, and D is the voltage conversion duty cycle.

[0092] Figure 6 This is a graph showing the duty cycle of the buck-boost converter according to the embodiment of this application.

[0093] Figure 6 A graph of the charging voltage V2 based on the voltage conversion duty cycle D is shown in the buck-boost converter 172.

[0094] In an exemplary embodiment, when the voltage conversion duty cycle D received by the buck-boost converter 172 from the generator controller 260 is less than 0.5, the rectified voltage V1 input to the buck-boost converter 172 can be output as a reduced charging voltage V2. When the duty cycle D is equal to 0.5, the charging voltage V2 can be the same as the rectified voltage V1. When the duty cycle D is greater than 0.5, the rectified voltage V1 can be boosted to generate a charging voltage V2 that is greater than the rectified voltage V1.

[0095] Figure 7 This is a flowchart illustrating the operation of a VCU controlling battery charging using a generator engine according to an embodiment of this application.

[0096] Reference Figure 7 In operation S710, VCU210 can monitor the input and output voltage of each component, and in operation S720, it determines whether the generator engine 150 is running.

[0097] For example, VCU210 can monitor the rectified voltage V1 from the power converter 170, the charging voltage V2 output to the battery 110, and the voltage of the battery 110.

[0098] When it is determined that the generator engine 150 is not running (operation S720 is No), VCU210 can continue to monitor the voltage in operation S710.

[0099] In an exemplary embodiment, VCU210 can determine whether the voltage of battery 110 is lower than a predetermined charging reference voltage and can control the operation of generator 150.

[0100] When it is determined that the generator engine 150 is running (operation S720 is yes), in operation S730, VCU210 can determine whether the voltage of the battery 110 is lower than the predetermined charging reference voltage.

[0101] The charging reference voltage can be based on the voltage corresponding to a specific state of charge (SOC) value for charging the battery 110 (e.g., as required). Furthermore, the VCU210 can determine whether the SOC of the battery 110 is lower than a predetermined charging reference SOC, rather than comparing the voltage of the battery 110 with the charging reference voltage.

[0102] When the voltage of battery 110 is greater than the predetermined charging reference voltage (Operation S730 is no), VCU210 can continue to monitor the voltage in operation S710.

[0103] When the voltage of battery 110 is less than the predetermined charging reference voltage (yes in operation S730), VCU210 can determine the charging voltage V2 in operation S740.

[0104] More specifically, VCU210 can determine the voltage of battery 110 and can determine a charging voltage V2 that is greater than the determined voltage of battery 110.

[0105] Subsequently, in operation S750, VCU210 can determine the voltage conversion duty cycle of the control signal output to power converter 170, and in operation S760, the control outputs a control signal corresponding to the determined voltage conversion duty cycle to power converter 170.

[0106] In an exemplary embodiment, VCU210 determines the voltage conversion duty cycle based on the rectified voltage V1 and the determined charging voltage V2, and can control the generator controller 260 to output a control signal corresponding to the determined voltage conversion duty cycle to the switch S of the buck-boost converter 172.

[0107] Next, in operation S770, VCU210 can determine whether the charging voltage V2 is greater than the voltage of battery 110.

[0108] When the charging voltage V2 is less than the voltage of the battery 110 (Operation S770 is no), VCU210 can re-determine in Operation S720 whether the generator engine 150 is running and whether the generator engine 150 is performing its power generation operation.

[0109] Subsequently, in operation S780, VCU210 can determine whether to maintain control over the charging voltage V2 of battery 110.

[0110] Specifically, VCU210 can control the charging voltage V2 by outputting a control signal corresponding to a determined voltage conversion duty cycle to the buck-boost converter 172 of the power converter 170. In an exemplary embodiment, even if the power output of the generator 160 and the voltage of the battery 110 change, VCU210 can adjust the magnitude of the supplied charging voltage V2 to stably charge the battery 110.

[0111] Furthermore, this application can provide (e.g., implement) code recorded on a computer-readable medium containing a program. Computer-readable media include (e.g., all) types of recording devices that store data readable by a computer system. Examples of computer-readable media include hard disk drives (HDDs), solid-state drives (SSDs), silicon disk drives (SDDs), ROM, RAM, CD-ROMs, magnetic tapes, floppy disks, optical data storage devices, etc. Therefore, the detailed description above should not be construed as limiting in (e.g., all) respects, but rather as exemplary. The scope of this application should be determined by a reasonable interpretation of the claims herein and includes (e.g., all) modifications within the scope of this application.

Claims

1. An electric vehicle comprising: Battery; engine; An electric motor, configured to generate electricity by receiving mechanical energy from an engine; A power converter configured to rectify AC power generated by a motor into DC power, convert the voltage of the rectified DC power into a charging voltage, and output the converted voltage to a battery; as well as The controller is configured to determine the voltage conversion duty cycle based on the rectified DC voltage and the battery voltage. The power converter converts the rectified DC voltage into a charging voltage based on a control signal corresponding to the voltage conversion duty cycle.

2. The electrified vehicle of claim 1, wherein, The power converter includes a buck-boost converter configured to boost or buck the charging voltage based on the voltage conversion duty cycle.

3. The electrified vehicle of claim 2, wherein, The buck-boost converter includes a switch disposed at an input terminal configured to receive rectified DC power, the switch being controlled to be turned on and off based on the control signal.

4. The electrified vehicle of claim 3, wherein, The switch located at the input terminal comprises multiple switching elements connected in series.

5. The electrified vehicle of claim 1, wherein, The motor includes a three-phase motor, and the power converter includes a three-phase rectifier configured to convert the three-phase alternating current generated by the motor into direct current.

6. The electrified vehicle of claim 1, wherein, The controller determines the charging voltage based on the battery voltage, and determines the voltage conversion duty cycle based on the charging voltage and the voltage of the rectified DC power.

7. The electrified vehicle of claim 1, wherein, The controller further determines whether the battery voltage is lower than a preset reference voltage, and controls the engine to run based on the battery voltage being lower than the preset reference voltage.

8. The electrified vehicle of claim 1, wherein, The engine operates in a preset drive mode based on its energy efficiency.

9. A method for controlling an electrified vehicle, the method comprising: The engine is operated by the controller; Electricity is generated by an electric motor by receiving mechanical energy from an engine; The power converter rectifies the alternating current (AC) generated by the motor into direct current (DC); The controller determines the voltage conversion duty cycle based on the rectified DC voltage and the battery voltage. The power converter converts the rectified DC voltage into a charging voltage based on a control signal corresponding to the voltage conversion duty cycle.

10. The method according to claim 9, wherein, The power converter includes a buck-boost converter configured to boost or buck the charging voltage based on the voltage conversion duty cycle.

11. The method according to claim 10, wherein, The buck-boost converter includes a switch disposed at an input terminal configured to receive rectified DC power, the switch being controlled to be turned on and off based on the control signal.

12. The method according to claim 11, wherein, The switch located at the input terminal comprises multiple switching elements connected in series.

13. The method according to claim 9, wherein, The motor includes a three-phase motor, and the power converter includes a three-phase rectifier configured to convert the three-phase alternating current generated by the motor into direct current.

14. The method according to claim 9, wherein, Determining the voltage conversion duty cycle includes: the controller determining the charging voltage based on the battery voltage, and determining the voltage conversion duty cycle based on the charging voltage and the voltage of the rectified DC power.

15. The method of claim 9, further comprising: Determine if the battery voltage is lower than the preset reference voltage; The engine operates based on the battery voltage being lower than a preset reference voltage.

16. The method according to claim 9, wherein, The engine operates in a preset drive mode based on its energy efficiency.

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