Charging system and procedure for vehicles

Abstract

Charging system for a vehicle, comprising: a power transmitter (100) that sends power to charge a battery of a vehicle; a charger (200) including a three-phase motor (210) and an inverter (220) connected to the three-phase motor (210) and receiving the power sent from the power transmitter (100) to charge the battery of the vehicle; an input voltage calculation processor (300) that selects one of a plurality of predetermined load ratios and calculates a value of an input voltage supplied to the charger (200) based on the selected load ratio and a voltage value of the battery of the vehicle; an input current calculation processor (400) that calculates a value of an input current input to the charger (200) based on the calculated value of the input voltage and a value of the current sent by the current transmitter (100); a current transmission controller (500) which instructs the calculated input current to be input to the charger (200) from the current transmitter (100); and a charging controller (600) that instructs the vehicle battery to be charged based on the calculated value of the input voltage and the voltage value of the vehicle battery.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a charging system and method for a vehicle, and more particularly to a charging system and method capable of reducing current ripple generated during a fast charging process of a battery for a vehicle. BACKGROUND

[0002] Eco-friendly vehicles such as electric vehicles (EVs) and plug-in hybrid electric vehicles (PHEVs) use electric vehicle supply equipment (EVSE) installed at a charging station to charge a battery.

[0003] One of the most important indicators for EVSE using a conventional motor inverter is charging efficiency, and one variable that has the greatest impact on charging efficiency is the ripple current of the charging current and the motor current. Since the charging efficiency of a charging system decreases as the amplitude of the ripple current increases, the ripple current should be reduced as much as possible.

[0004] For this reason, according to the state of the art, as in Fig. 1, by additionally connecting an inductor Lch to a neutral terminal of the motor, the ripple of the charging current and the motor current during charging is reduced. However, the method as described above has a limitation that the cost increases and a size is increased due to the additional inductor. In addition, as another prior art method, as shown in Fig. 2, the current ripple during charging is reduced by using three separate inductors and three parallel boost converters along with a boosted PWM switching scheme. However, unlike the conventional three parallel boost amplifiers using the three separate inductors, a multi-input charging system has a limitation in that a bias may vary because each phase uses a motor, which interfere with each other. The contents described as prior art have been provided only to assist in understanding the background of the present disclosure and should not be considered as corresponding to the prior art known to those of ordinary skill in the art.

[0005] DE 10 2016 110 870 A1 relates to a charging system for charging a high-voltage battery of an electrically powered vehicle, comprising at least one electric machine, a pulse-controlled inverter, and a DC charging station connection. The electric machine comprises n stator windings, wherein the n stator windings are interconnected at a common star point, and the star point is connected to a pole of the DC charging station connection.

[0006] DE 11 2011 105 105 T5 relates to a power supply system for a vehicle. When a ground fault occurs in a drive device for driving a motor, high-voltage noise enters a high-voltage detector through a connection node of the Y capacitor formed by a pair of capacitors in a DC / DC converter. A controller of the DC / DC converter limits the duty cycle of the switching elements forming a full-bridge circuit on the primary side in the event that a failure due to a ground fault of the drive device is detected.

[0007] D3 DE 10 2010 027 705 A1 relates to an electric motor drive device. The electric motor drive device includes an inverter that adjusts the voltage applied to an AC electric motor to drive the AC electric motor, a capacitor charged by a current supplied from a DC power supply, and a control circuit that controls the inverter so that the AC electric motor rotates at a specific speed. SUMMARY

[0008] An object of the present disclosure is to provide a charging system and method for a vehicle capable of reducing a current ripple generated during a rapid charging process of the vehicle.

[0009] According to one embodiment of the present disclosure, a charging system for a vehicle includes: a power transmitter that sends power to charge a battery of a vehicle; a charger that includes a three-phase motor and an inverter connected to the three-phase motor and receives the power sent from the power transmitter to charge the battery of the vehicle; an input voltage calculation processor that selects one of a plurality of predetermined load ratios and calculates a value of an input voltage supplied to the charger based on the selected load ratio and a voltage value of the battery of the vehicle; an input current calculation processor that calculates a value of an input current input to the charger based on the calculated value of the input voltage and a value of the current sent by the power transmitter;a current transmitter controller that instructs the calculated input current to be input to the charger from the current transmitter; and a charging controller that instructs the vehicle's battery to be charged based on the calculated input voltage value and the voltage value of the vehicle's battery.

[0010] The charger may include a first capacitor and a second capacitor connected in parallel with the inverter; a second relay connected to a neutral terminal of the three-phase motor; and a first relay and a third relay connected to the inverter.

[0011] The inverter can receive a three-phase signal from the three-phase motor via a variety of drive elements that are connected to each other.

[0012] The current transmitter may include a current generator providing current; and a third capacitor and a fourth capacitor connected in parallel with the current generator.

[0013] The charging controller can connect the first relay and the third relay to charge the vehicle battery when the calculated value of the input voltage is equal to the voltage value of the vehicle battery.

[0014] The charging controller can amplify the input value through the inverter by connecting the second relay and the third relay, thereby charging the vehicle's battery when the calculated value of the input voltage is smaller than the voltage value of the vehicle's battery.

[0015] The charging controller may provide three pulse width modulation (PWM) signals with the selected duty ratio to a plurality of drive elements of the inverter connected to the corresponding phases of the three-phase motor when the calculated value of the input voltage is less than the voltage value of the vehicle's battery.

[0016] The three PWM signals can all have a phase difference of 120°.

[0017] The plurality of predetermined load ratios may include 0, 1 / 3, 2 / 3 and 1.

[0018] According to another embodiment of the present disclosure, a fast charging method for a vehicle includes: determining charging current provided from the power transmitter to charge the vehicle's battery; selecting one of a plurality of predetermined load ratios and calculating a value of an input voltage provided to the charger based on the selected load ratio and a voltage value of the vehicle's battery; calculating a value of an input current input to the charger based on the calculated value of the input voltage and a value of the current provided from the power transmitter; instructing the calculated input current to be input to the charger from the power transmitter; and instructing the vehicle's battery to be charged based on the calculated value of the input voltage and the voltage value of the vehicle's battery.

[0019] The rapid charging method for a vehicle may further include recalculating the input voltage and input current and controlling the recalculated input voltage and input current to be input to the charger when charging current is changed in a process in which the calculated input voltage and input current are input to the charger from the power transmitter to charge the battery of the vehicle. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a diagram illustrating a configuration of a charging system for a vehicle according to a conventional embodiment. Fig. 2 is a diagram illustrating a configuration of a charging system for a vehicle according to another conventional embodiment. Fig. 3 is a diagram illustrating a configuration of a charging system for a vehicle according to an embodiment of the present disclosure. Fig. 4 is a diagram illustrating a pulse width modulation (PWM) signal provided to a drive element of an inverter connected to each of the phases of a three-phase motor and a common mode voltage correspondingly in the charging system for a vehicle according to an embodiment of the present disclosure. Fig. 5 is a diagram illustrating a PWM signal provided to a drive element of an inverter connected to each of the phases of a three-phase motor, and a common mode voltage corresponding thereto, in the charging system for a vehicle according to another embodiment of the present disclosure. Fig. 6A to 6D are graphs illustrating simulation result data showing ripples of a motor current, an input current, an input voltage, and a leakage current in a case where three PWM signals with a duty ratio of 1 / 3 and each having a phase difference of 120°C are provided to an inverter. Fig. 7A to 7D are graphs illustrating simulation result data showing ripples of a motor current, an input current, an input voltage, and a leakage current in a case where the three PWM signals with a duty ratio of 2 / 3 and each having a phase difference of 120° are provided to an inverter. Fig. 8 is a flowchart illustrating a flow of a rapid charging method for a vehicle according to an embodiment of the present disclosure. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0020] Hereinafter, a multi-input charging system and method for an ecological vehicle according to embodiments of the present disclosure will be described with reference to the accompanying drawings.

[0021] Fig. 3 is a diagram illustrating a configuration of a charging system for a vehicle according to an embodiment of the present disclosure, Fig. 4 is a diagram illustrating a pulse width modulation (PWM) signal provided to a drive element of an inverter provided with each of the phases of a three-phase motor in the charging system for a vehicle according to an embodiment of the present disclosure, Fig. 5 is a diagram illustrating a PWM signal provided to a drive element of an inverter connected to each of the phases of a three-phase motor in the charging system for a vehicle according to another embodiment of the present disclosure, Fig. 6A-6D are diagrams illustrating simulation result data showing ripples of a motor current, an input current, an input voltage, and a leakage current in a case where three PWM signals with a duty ratio of 1 / 3 and each having a phase difference of 120° are provided to an inverter, and Fig. 7 is a diagram illustrating simulation result data showing ripples of a motor current, an input current, and a leakage current in a case where three PWM signals with a duty ratio of 2 / 3 and each having a phase difference of 120° are provided to an inverter.

[0022] As in Fig. 3, a charging system for a vehicle according to an embodiment of the present disclosure may include a current transmitter 100, a charger 200, an input voltage calculation processor 300, an input current calculation processor 400, a current transmission controller 500, and a charging controller 600. Here, the input voltage calculation processor 300, the input current calculation processor 400, the current transmission controller 500, and the charging controller 600 are hardware devices connected to or embedded within a processor 10.

[0023] In various embodiments of the present disclosure, processor 10 is a hardware device and may be a central processing unit (CPU) within a computer that executes the instructions of a computer program by performing basic arithmetic, logical control of the input / output (I / O) operations specified by the instructions, and capable of controlling one or more of the electrical systems in a vehicle. Processor 10 may also be an electronic control unit (ECU) or communicate with the ECU installed in the vehicle.

[0024] The power transmitter 100 is designed to provide power for charging a battery of a vehicle. Specifically, the power transmitter 100 may include a power generator 110 that provides the power, and a third capacitor C3 and a fourth capacitor C4 connected in parallel with the power generator 110.

[0025] The charger 200 is supplied with the power provided by the power generator 110 to charge the vehicle's battery. Specifically, the charger 200 may include a three-phase motor 210, an inverter 220 connected to the three-phase motor 210, a first capacitor C1 connected in parallel to the inverter 220, a second capacitor C2, a second relay R2 connected to a neutral terminal of the three-phase motor 210, and a first relay R1 and a third relay R2 connected to the inverter 220, as shown in Fig. 3. Here, inverter 220 may receive a three-phase signal from a three-phase motor 210 via a plurality of drive elements connected to each other within inverter 220. In this case, the three-phase signal may include an input voltage and an input current input to each of the phases of three-phase motor 210. For example, the plurality of drive elements includes switching elements (IGBTs) included in an inverter, as is known.

[0026] The input voltage calculation processor 300 may select any one of a plurality of predetermined duty ratios. Here, the plurality of predetermined duty ratios may include 0, 1 / 3, 2 / 3, and 1. Specifically, the input voltage calculation processor 300 may select a specific duty ratio of the plurality of predetermined duty ratios based on the current supplied by the power transmitter 100. For example, in a case where the vehicle's battery can be sufficiently charged with only the current supplied by the power transmitter 100, the input voltage calculation processor 300 may select a duty ratio of 1 of the plurality of load ratios.In other words, according to one embodiment, in a case where the battery of the vehicle is an 800V battery and the power transmitter 100 can provide sufficient power to charge the 800V battery, the input voltage calculation processor 300 may select the duty ratio of 1. That is, the above-mentioned case corresponds to a case where it is not necessary to boost the voltage by the inverter 220.

[0027] However, according to one embodiment, in a case where the vehicle's battery may not be sufficiently charged with only the current provided by the power transmitter 100, that is, in a case where it is necessary to boost the voltage by the inverter 220, the input voltage calculation processor 300 may select 1 / 3 or 2 / 3, which is a duty ratio less than 1.

[0028] The input voltage calculation processor 300 may calculate an input voltage value provided to the charger by Equation 1 below, based on the load ratio and voltage value of the vehicle's battery selected using the method described above. For example, in a case where the selected load ratio is 1 / 3 and the vehicle's battery is a 600V battery, the input voltage value provided to the charger 200 may be 200V according to the equation below. Vin=D×Vbat Vin: Input voltage, D: Load ratio, Vbat: Voltage of vehicle battery

[0029] When the input voltage value calculated based on the load ratio and the voltage value of the vehicle's battery is equal to the voltage value of the vehicle's battery, the charging controller 600 may connect the first relay R1 to the third relay R3 to thereby charge the vehicle's battery. As described above, the above-mentioned case corresponds to a case where the vehicle's battery can be sufficiently charged with only the power supplied by the power transmitter 100.More specifically, according to one embodiment, in a case where the battery of the vehicle is an 800V battery, the selected load ratio is 1, and the value of the input voltage calculated accordingly in Equation 1 is 800V, the charging controller 600 may be connected to the power transmitter 100 and the battery of the vehicle in series with each other by connecting the first relay R1 and the third relay R3 with each other, thereby charging the battery of the vehicle.

[0030] On the other hand, in a case where the value of the input voltage calculated based on the load ratio and the voltage value of the vehicle's battery is smaller than the voltage value of the vehicle's battery, the charging controller 600 may boost the corresponding input voltage through the inverter 220 by connecting the second relay R2 to the third relay R3, thereby charging the vehicle's battery. As described above, the above-mentioned case corresponds to a case where the vehicle's battery cannot be sufficiently charged with only the power supplied by the power transmitter 100.More specifically, according to one embodiment, in a case where the vehicle battery is a 900V battery, the selected load ratio is 1 / 3, and the value of the input voltage calculated according to Equation 1 is 300V, the charging controller 600 may boost the corresponding input voltage through the inverter 220 by connecting the second relay R2 to the third relay R3, thereby charging the vehicle battery.

[0031] When the value of the input voltage calculated based on the load ratio and the voltage value of the vehicle's battery is smaller than the voltage value of the vehicle's battery, the charging controller 600 may each provide three PWM signals with the load ratio selected at the time of calculating the value of the corresponding input voltage to a plurality of drive elements within the inverter 220 connected to the respective phases of the three-phase motor 210. In this case, the three PWM signals each provided to the plurality of drive elements within the inverter 220 may have a selected specific load ratio and may each have a phase difference of 120°, as shown in Fig. 4 and Fig. 5 illustrated.

[0032] Additionally, in a case where the value of the calculated input voltage is smaller than the voltage value of the vehicle's battery, the duty ratio selected by the charging controller 600 may be 1 / 3 or 2 / 3. That is, in the case where the value of the calculated input voltage is smaller than the voltage value of the vehicle's battery, the charging controller 600 may provide the three PWM signals with the duty ratio of 1 / 3 or 2 / 3 and each having the phase difference of 120° to the inverter 220. In this case, the reason why the charging controller 600 selects the duty ratio of 1 / 3 or 2 / 3 will be described in more detail below.

[0033] The input current calculation processor 400 may calculate a value of the input current input to the charger 200 based on the value of the calculated input voltage and the value of the current provided by the current transmitter 100 after calculating the value of the input voltage, and the current transmission controller 500 may input the calculated input current to the charger 200 from the current transmitter 100. Here, the input current calculation processor 400 may calculate the value of the input current via Equation 2 below. Iin=P / Vin Iin: input current, P: current provided by current transmitter, Vin: input voltage

[0034] Referring to Fig. 3, in the charging system for a vehicle according to the present disclosure, in a case where the power transmitter 100 and the charger 200 are connected to each other to charge the vehicle's battery, a leakage current may be generated, which reduces the efficiency of the charging system. Here, the cause of the leakage current relates to a frequency and amplitude of a common mode voltage Vsn, and when the frequency of the common mode voltage Vsn is 0, the leakage current is not generated. That is, in order to block the generation of leakage, it is necessary to make a variation of the common mode voltage Vsn close to 0. Here, the common mode voltage Vsn, which is a voltage between nodes (S and n), may be a voltage between a neutral terminal of the three-phase motor 210 and a virtual neutral terminal of the DC terminal of the inverter 220.

[0035] More specifically, referring to Fig. 4 to 7, in a case where the three PWM signals with the duty ratio of 1 / 3, each having a phase difference of 120°, are provided to the inverter 220, or the three PWM signals with the duty ratio of 2 / 3, each having a phase difference of 120°, are provided to the inverter 220, the common mode voltage Vsn can be maintained at a single value. That is, the frequency of the common mode voltage Vsn is close to 0, thereby making it possible to block the generation of the leakage current during charging of the vehicle's battery. As a result, the efficiency of the charging system can be further improved.

[0036] Furthermore, with reference to Fig. 6 and Fig. 7 The input current Vin, the motor current, and the leakage current can all be reduced by providing the three PWM signals, each with a duty ratio of 1 / 3 or 2 / 3 and a phase difference of 120°, to the inverter. As a result, the efficiency of the charging system can be improved.

[0037] In other words, according to the present disclosure, in the case where the vehicle's battery is not sufficiently charged with only the current supplied by the power transmitter 100, the charging controller 600 charges the vehicle's battery through the boosting process using the inverter by connecting the second relay R2 and the third relay R3 together. In this case, the charging controller 600 can boost the vehicle's battery to the input voltage by supplying the three PWM signals, each having a duty ratio of 1 / 3 or 2 / 3 and a phase difference of 120°, to the inverter 220 according to the value of the current supplied by the power transmitter 100, and can all reduce the input current Vin, the motor current, and the leakage current during the charging process. As a result, the efficiency and stability of the charging system can be further improved.

[0038] Fig. 8 is a flowchart illustrating a flow of a fast charging method for a vehicle according to an embodiment of the present disclosure. As shown in Fig.8, a fast charging method for a vehicle may include determining the charging current provided by the power transmitter for charging the vehicle's battery, selecting one of a plurality of predetermined load ratios and calculating a value of an input voltage provided to the charger based on the selected load ratio and a voltage value of the vehicle's battery; calculating a value of an input current input to the charger based on the calculated value of the input voltage and a value of the current provided from the power transmitter; and commanding the calculated input current to be input to the charger from the power transmitter; and commanding the vehicle's battery to be charged based on the calculated value of the input voltage and the voltage value of the vehicle's battery.

[0039] In addition, the rapid charging method for a vehicle may further include recalculating the input voltage and the input current and controlling the recalculated input voltage and the input current to be input to the charger in a case where the charging current is changed in a process in which the calculated input voltage and the input current are input to the charger from the power transmitter to charge the battery of the vehicle.

[0040] Since detailed technical characteristics in the respective operations of the rapid charging method for a vehicle are the same as those of the charging system for a vehicle, a detailed description thereof is omitted.

[0041] As described above, according to the present disclosure, the ripple current generated during the rapid charging process of the vehicle's battery can be reduced, making it possible to further improve the charging efficiency of the charging system.

[0042] In addition, the use of elements such as inductor, capacitor and the like is minimized, making it possible to reduce the cost.

[0043] Furthermore, the leakage current in the fast charging process of the vehicle's battery is reduced, which makes it possible to improve the stability of the charging system.

Claims

[1] Charging system for a vehicle, comprising: a power transmitter (100) that sends power to charge a battery of a vehicle; a charger (200) including a three-phase motor (210) and an inverter (220) connected to the three-phase motor (210) and receiving the power sent from the power transmitter (100) to charge the battery of the vehicle; an input voltage calculation processor (300) that selects one of a plurality of predetermined load ratios and calculates a value of an input voltage supplied to the charger (200) based on the selected load ratio and a voltage value of the battery of the vehicle; an input current calculation processor (400) that calculates a value of an input current input to the charger (200) based on the calculated value of the input voltage and a value of the current sent by the current transmitter (100); a current transmission controller (500) which instructs the calculated input current to be input to the charger (200) from the current transmitter (100); and a charging controller (600) that instructs the vehicle battery to be charged based on the calculated value of the input voltage and the voltage value of the vehicle battery. [2] The charging system of claim 1, wherein the charger (200) includes: a first capacitor and a second capacitor connected in parallel to the inverter (220); a first relay connected to the converter (220); a second relay connected to a neutral terminal of the three-phase motor (210); and a third connected to the converter (220). [3] The charging system of claim 1, wherein the inverter (220) receives a three-phase signal from the three-phase motor (210) via a plurality of drive elements connected together. [4] Charging system according to claim 1, wherein the current transmitter (100) includes: a power generator (110) providing power; and a third capacitor and a fourth capacitor connected in parallel to the current generator (110). [5] The charging system according to claim 2, wherein the charging controller (600) connects the first relay and the third relay to charge the battery of the vehicle when the calculated value of the input voltage is equal to the voltage value of the battery of the vehicle. [6] The charging system according to claim 2, wherein the charging controller (600) amplifies the input value via the inverter (220) by connecting the second relay and the third relay to thereby charge the battery of the vehicle when the calculated value of the input voltage is smaller than the voltage value of the battery of the vehicle. [7] The charging system of claim 1, wherein the charging controller (600) provides three pulse width modulation (PWM) signals with the selected duty ratio to a plurality of drive elements of the inverter (220) connected to the corresponding phases of the three-phase motor (210) when the calculated value of the input voltage is less than the voltage value of the battery of the vehicle. [8] Charging system according to claim 7, wherein the three PWM signals each have a phase difference of 120°. [9] The charging system of claim 1, wherein the plurality of predetermined load ratios includes 0, 1 / 3, 2 / 3, and 1. [10] A rapid charging method for a vehicle according to claim 1, comprising: Determining, by a processor, charging current provided from the current transmitter (100) to charge the battery of the vehicle; Selecting, by the processor, one of a plurality of predetermined load ratios and calculating a value of an input voltage provided to the charger (200) based on the selected load ratio and a voltage value of the vehicle's battery; Calculating, by the processor, a value of an input current input to the charger (200) based on the calculated value of the input voltage and a value of the current provided from the current transmitter (100); Instructing, by the processor, the calculated input current to be input to the charger (200) from the current transmitter (100); and Instruct, by the processor, the vehicle's battery to be charged based on the calculated value of the input voltage and the voltage value of the vehicle's battery. [11] Fast charging method according to claim 10, further comprising: Recalculating, by the processor, the input voltage and input current and controlling the recalculated input voltage and input current to be input to the charger (200) when changing charging current in a process in which the calculated input voltage and input current are input to the charger (200) from the current transmitter (100) to charge the battery of the vehicle.

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