Electric vehicle charging apparatus

Abstract

According to an embodiment, provided is an electric vehicle charging apparatus comprising: an AC / DC converter for converting AC power supplied from an AC power supply source into DC power; a DC / DC converter for converting the DC power into a charging voltage for an electric vehicle battery; an output filter for transmitting the charging voltage to a charging terminal of the electric vehicle battery; and a discharge circuit unit including a voltage sensor for measuring the remaining voltage of the output filter at the point in time when charging of the electric vehicle battery ends, a switching element for performing an on / off operation in response to a switching signal generated on the basis of the remaining voltage, and a resistor element that discharges the remaining voltage by being applied with a current when the switching element operates in an on state.

Description

electric vehicle charging device

[0001] The embodiment relates to an electric vehicle charging device.

[0002] After an electric vehicle is fully charged, the process of discharging the remaining power within the charging module can cause excessive current to flow within the discharge circuit components within a short period of time, exceeding the specifications. If the discharge switch is not controlled, the remaining current will flow to the discharge resistor as much as possible, increasing the possibility of overheating or damage to the discharge resistor and other components. While increasing component specifications can ensure durability, this also increases the number of components, component size, and system cost. Therefore, a control system that can efficiently perform discharge while preventing component damage and heat generation is needed.

[0003] The technical problem to be achieved by the present invention is to provide an electric vehicle charging device capable of safely removing residual power remaining in a battery and power module.

[0004] According to an embodiment, an electric vehicle charging device is provided, including an AC-DC converter that converts AC power supplied from an AC power source into DC power; a DC-DC converter that converts the DC power into a charging voltage of an electric vehicle battery; an output filter that transmits the charging voltage to a charging terminal of the electric vehicle battery; and a discharge circuit unit that includes a voltage sensor that measures a residual voltage of the output filter at a time point at which charging of the electric vehicle battery ends, a switching element that performs an on-off operation according to a switching signal generated based on the residual voltage, and a resistance element that discharges the residual voltage by applying current when the switching element is operated in an on state.

[0005] The above discharge circuit may further include a controller that generates the switching signal by calculating the duty cycle of the switching element based on the residual voltage.

[0006] The controller can calculate an average current flowing through the resistance element at preset cycles based on the residual voltage, and calculate the duty cycle based on the average current.

[0007] The above controller can calculate the average current based on a preset reference power.

[0008] The above controller can calculate the average current so that a constant amount of power is discharged through the resistance element at each preset cycle.

[0009] The controller can increase the duty cycle according to the amount of decrease in the residual voltage.

[0010] The above discharge circuit may further include a switch driver that controls the on / off operation of the switching element according to the switching signal.

[0011] The above switching element and the above resistance element can be connected in series.

[0012] An electric vehicle charging device according to an embodiment can prevent component damage during a discharging process and improve the reliability of the system.

[0013] In addition, by effectively controlling the current flowing within the discharge circuit, there is no need to use more components than necessary, and thus the number of components can be reduced, which is expected to have the effect of reducing the size and cost of the system.

[0014] As a result, it enables safe discharge after charging of electric vehicles and contributes to ensuring safety during the unplugging process.

[0015] Figure 1 is a conceptual diagram of an electric vehicle charging device according to an embodiment.

[0016] Figure 2 is a block diagram of an electric vehicle charging device according to an embodiment.

[0017] Figure 3 is a drawing for explaining a power module according to an embodiment.

[0018] Figures 4 and 5 are conceptual diagrams of a discharge circuit according to an embodiment.

[0019] FIGS. 6 to 10 are drawings for explaining the operation of an electric vehicle charging device according to an embodiment.

[0020] Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the attached drawings.

[0021] However, the technical idea of ​​the present invention is not limited to some of the embodiments described, but can be implemented in various different forms, and within the scope of the technical idea of ​​the present invention, one or more of the components between the embodiments can be selectively combined or substituted for use.

[0022] In addition, terms (including technical and scientific terms) used in the embodiments of the present invention may be interpreted as having a meaning that can be generally understood by a person of ordinary skill in the technical field to which the present invention belongs, unless explicitly and specifically defined and described, and terms that are commonly used, such as terms defined in a dictionary, may be interpreted in consideration of the contextual meaning of the relevant technology.

[0023] Additionally, the terms used in the embodiments of the present invention are intended to describe the embodiments and are not intended to limit the present invention.

[0024] In this specification, the singular may also include the plural unless specifically stated otherwise in the phrase, and when it is described as “A and / or at least one (or more) of B, C”, it may include one or more of all combinations that can be combined with A, B, C.

[0025] Additionally, in describing components of embodiments of the present invention, terms such as first, second, A, B, (a), (b), etc. may be used.

[0026] These terms are intended only to distinguish one component from another, and are not intended to limit the nature, order, or sequence of the component.

[0027] And, when a component is described as being 'connected', 'coupled' or 'connected' to another component, it may include not only cases where the component is directly connected, coupled or connected to the other component, but also cases where the component is 'connected', 'coupled' or 'connected' by another component between the component and the other component.

[0028] Additionally, when described as being formed or arranged "above or below" each component, "above" or "below" includes not only cases where the two components are in direct contact with each other, but also cases where one or more other components are formed or arranged between the two components. Furthermore, when expressed as "above" or "below", it can include the meaning of a downward direction as well as an upward direction based on one component.

[0029] Hereinafter, embodiments will be described in detail with reference to the attached drawings. Regardless of the drawing numbers, identical or corresponding components are given the same reference numbers, and redundant descriptions thereof will be omitted.

[0030] Figure 1 is a conceptual diagram of an electric vehicle charging device according to an embodiment, and Figure 2 is a block diagram of the configuration of an electric vehicle charging device according to an embodiment.

[0031] Referring to FIGS. 1 and 2, an electric vehicle charging device (100) according to an embodiment is a device that connects to a power outlet installed in an apartment or house, as well as a public place or public building, through a power outlet connection connector (C) formed on the outside, and supplies power supplied from the power outlet to an electric vehicle (200) connected to the electric vehicle (200) connection connector (C) to charge a battery.

[0032] An electric vehicle charging device (100) receives a charging control signal from an external charger operating system (300), switches the power connection between a power outlet and an electric vehicle (200) according to the received control signal, and supplies AC commercial power applied through the power outlet to the electric vehicle (200).

[0033] An electric vehicle charging device (100) may include a communication unit (110), a power module (120), a processor (130), a display unit (140), a user interface unit (150), and a memory (160).

[0034] Additionally, the electric vehicle charging device (100) may be equipped with a connector (C) for connection to an electric vehicle (200).

[0035] The communication unit (110) can transmit and receive data by communicating with a user terminal (400) or charger operating system (300) possessed by an electric vehicle (200) driver.

[0036] The power module (120) can supply commercial power supplied from a power outlet to the electric vehicle (200) according to the switching of the processor (130).

[0037] The power module (120) can be configured to include a rectifier, an AC-DC converter, a DC-DC converter, etc., and can rectify commercial power supplied from a power outlet through the rectifier and then convert it into DC power used in an electric vehicle (200) through the AC-DC converter and the DC-DC converter.

[0038] The power module (120) converts AC power supplied from a power outlet into DC power used by the electric vehicle (200) when the electric vehicle (200) uses DC power and supplies it. When the electric vehicle (200) uses AC power, the power can be supplied to the electric vehicle (200) as is without any additional power conversion.

[0039] The memory (160) stores a program and various data for controlling the charging device, and can load the program or read or write data at the request of the processor (130).

[0040] The processor (130) can perform overall control of the charging device. The processor (130) can be configured to execute programs and instructions stored in the memory (160).

[0041] The processor (130) can control the power connection between the power module (120) and the electric vehicle (200) to be switched according to the charging station operating system or operation mode, so that power is supplied from the power module (120) to the electric vehicle (200) and charging is performed.

[0042] The processor (130) can control whether to supply power to the electric vehicle (200) through the power module (120). The electric vehicle (200) charging device can additionally include a protection circuit that blocks the connection between the power module (120) and the electric vehicle (200) when overcurrent, overvoltage, or overcharging occurs.

[0043] The processor (130) can calculate the amount of charging power supplied from the power module (120) to the electric vehicle (200). For example, the processor (130) can calculate the amount of power by calculating the product of the current supplied to the electric vehicle (200) and the charging voltage.

[0044] When charging is complete, the processor (130) can transmit the calculated charging power amount to the user terminal through the communication unit (110), thereby allowing the user to check the charging power amount compared to the charging cost paid.

[0045] The display unit (140) may be provided on the front of the electric vehicle charging device (100) and may be composed of an LED, LCD, etc., and may display information on the operating status of the electric vehicle charging device (100). In addition, the display unit (140) may be composed of a touch screen capable of detecting input, and may receive a user's request to instruct the charging device.

[0046] The user interface unit (150) may be configured as a hard type interface provided at a predetermined location outside the charging device, or as a soft type interface that can be touched on the display unit (140) to receive various requests related to the operation of the charging device.

[0047] Figure 3 is a drawing for explaining a power module according to an embodiment.

[0048] A charging device according to an embodiment can perform an operation of charging an electric vehicle by receiving power from an AC power supply source (600).

[0049] In an embodiment, an AC power supply source (600) can supply AC power to an electric vehicle charging system using power provided from a national power grid or a local power grid.

[0050] The AC power supply (600) can use various voltages such as 110 V, 220 V, and 380 V, and can supply AC power at a frequency of 50 Hz or 60 Hz.

[0051] The AC power supply source (600) can maintain voltage and frequency so that the electric vehicle charging system can receive power stably and meet the power quality (Voltage, Current THD) standards.

[0052] An AC power supply source (600) may include an AC generator that generates an induced electromotive force (Faraday's law) through the interaction of a magnetic flux (magnetic field) and a coil, and a transformer that converts the voltage level to supply it to transmission, distribution, and end users.

[0053] Power from an AC power supply source (600) can be transmitted to a charging device through a transmission line (high voltage), distribution line (medium voltage, low voltage), etc.

[0054] In addition, the AC power supply source (600) may include a load management device that maintains the stability of the power grid and suppresses voltage fluctuations, thereby balancing power demand and supply in the distribution section, adjusting power distribution during peak loads, or cutting off some loads in emergency situations.

[0055] In addition, the AC power supply source (600) can quickly cut off power in abnormal conditions such as short circuit, overload, and ground fault through a power protection system, and prevent power surges caused by excessive voltage or lightning.

[0056] The power module (120) is a key component that performs power conversion to efficiently charge an electric vehicle battery. Electric vehicle charging devices require a complex power conversion process to ensure charging speed, efficiency, and stability. During this process, the power module (120) can convert input power (AC or DC) into voltage and current suitable for the vehicle's battery.

[0057] The power module (120) can perform multiple power conversion stages and may include an AC-DC converter (121), a PFC circuit (122), a DC-DC converter (123), an output filter (124), and a discharge circuit (125).

[0058] The AC-DC converter (121) is a rectifier that can perform an operation of converting AC power input to the charging device (100) into DC power. The AC-DC converter (121) can convert AC voltage into DC voltage using a diode bridge or an active rectification circuit. Active rectification can generally provide higher efficiency.

[0059] A Power Factor Correction (PFC) circuit (122) can improve power factor, thereby increasing power efficiency in the power grid and reducing electromagnetic interference (EMI). The PFC circuit (122) can reduce power loss and minimize impact on the power grid by matching the input current waveform to the AC power voltage waveform.

[0060] The DC-DC converter (123) can convert the rectified DC voltage into a voltage and current suitable for the battery of an electric vehicle. The DC-DC converter (123) can regulate the DC voltage using a CLLC resonant converter, an LLC resonant converter, or a simple buck converter. The CLLC resonant converter is particularly high in efficiency and low EMI, making it frequently used in electric vehicle charging devices.

[0061] The output filter (124) can remove ripple voltage from the output of the DC-DC converter (123) and provide stable DC power, thereby improving battery protection and charging efficiency. The output filter (124) can reduce voltage ripple and generate pure DC power using an LC filter (inductor and capacitor).

[0062] The power module (120) can process power in the following steps.

[0063] First, AC power input to the charging device (100) can be converted into DC power by an AC-DC converter (121). In this process, a PFC circuit (122) can be used to improve the power factor. This can optimize power usage from the power grid and reduce power loss.

[0064] The rectified DC voltage can be converted into a voltage suitable for the battery of an electric vehicle in a DC-DC converter (123). At this stage, voltage and current control is very important, and the voltage and current can be controlled in real time according to the battery's state of charge by a processor (130).

[0065] The converted DC voltage can be stabilized by passing through an output filter (124). The output filter (124) can remove voltage ripple and noise to provide DC power to the battery.

[0066] The processor (130) manages the entire charging process and can adjust the charging voltage and current according to the battery condition. This prevents overcharging, overheating, or other damage to the battery.

[0067] Through this process, the power module (120) can convert AC or DC power into the power required for the electric vehicle battery with minimal loss. Furthermore, it can supply a constant and stable power to the electric vehicle battery, thereby increasing charging efficiency and extending battery life.

[0068] Additionally, it effectively dissipates heat generated during the charging process, maintaining module performance and stability. Furthermore, it detects overvoltage, overcurrent, and overheating to protect the charging system and ensure safe charging.

[0069] Figures 4 and 5 are conceptual diagrams of a discharge circuit according to an embodiment. Referring to Figures 4 and 5 together, a discharge circuit (500) according to an embodiment may include a voltage sensor (510), a controller (520), a switch driver (530), a switching element (540), and a resistance element (550).

[0070] When the discharge circuit (500) detects a charging completion signal, it measures the residual voltage of the power module under the control of the controller (520), and controls the on / off operation of the switching element (540) according to the residual voltage to discharge the residual voltage through the resistance element (550).

[0071] The voltage sensor (510) is connected to both ends of the output filter, which is the output terminal of the power module, and can measure the voltage of the power line.

[0072] When a charging completion signal is detected under the control of the controller (520), the voltage sensor (510) can measure the voltage of the power line of the output filter at the end of charging of the electric vehicle battery to calculate the residual voltage value.

[0073] The controller (520) can generate a switching signal by calculating the duty cycle of the switching element (540) based on the residual voltage.

[0074] In the embodiment, the duty cycle is a numerical value representing the ratio of time that the switching element (540) operates in the on state in one period of the switching signal, and the period may mean the time it takes for the switching signal to go through one complete on-off cycle.

[0075] The controller (520) can convert the residual voltage measured by the voltage sensor (510) into digital data and calculate an average current based on the current residual voltage. The controller (520) can determine that discharge is necessary if the residual voltage is greater than a preset value, and can generate a switching signal that controls the operation of the switching element (540) for discharge.

[0076] For example, the controller (520) may calculate an average current flowing through the resistance element (550) at preset cycles based on the residual voltage, and may calculate a duty cycle based on the average current. For example, the controller (520) may calculate the average current based on a preset reference power.

[0077] At this time, the controller (520) can calculate an average current so that a constant amount of power is discharged through the resistance element (550) at preset cycles.

[0078] Additionally, the controller (520) can increase the duty cycle depending on the amount of decrease in the residual voltage.

[0079] The controller (520) can calculate the discharge power to be discharged through the resistance element (550) at preset cycles based on the residual voltage. At this time, the controller (520) can calculate the discharge power so as not to exceed the preset reference power. Here, the reference power may mean a power value set in advance so that the components of the power module are not damaged by the power discharged during one cycle. That is, since the components of the power module may be damaged when the power is discharged in excess of the reference power, the controller (520) can calculate the discharge power so that the power is discharged at a value lower than the reference power.

[0080] The controller (520) can calculate the average current based on the discharge power. The average current may refer to the amount of current required to output the discharge power for one cycle through the resistance element (550). Since the power is proportional to the current value, the controller (520) can control the amount of power discharged for each cycle to be constant by increasing the amount of current flowing through the resistance element (550) as the residual voltage increases. That is, the controller (520) can calculate the average current for each cycle so that the amount of current flowing through the resistance element (550) increases as the residual voltage decreases. Therefore, the average current for each cycle can be calculated to be inversely proportional to the residual voltage.

[0081] The controller (520) can calculate the duty cycle based on the average current. The controller (520) can adjust the duty cycle so that the amount of current flowing through the resistance element (550) for each cycle converges to the average current. The controller (520) can calculate a higher duty cycle when the average current is higher, and a lower duty cycle when the average current is lower. That is, the controller (520) can increase the time for which the switching element (540) operates in the on state in a cycle in which the residual voltage is measured to be small and the average current is calculated to be high, and can increase the time for which the switching element (540) operates in the off state in a cycle in which the residual voltage is measured to be large and the average current is calculated to be low.

[0082] The controller (520) can generate a switching signal based on a duty cycle. The controller (520) can output the period during which the switching element (540) operates in an on state and the period during which it operates in an off state as waveform data according to the duty cycle. That is, the controller (520) can control the switching element (540) so that the amount of power discharged through the resistance element (550) for each cycle is constant through PWM control using the switching signal.

[0083] The switch driver (530) can control the on / off operation of the switching element (540) according to a switching signal. For example, the switch driver (530) can be configured as a MOSFET / IGBT driver and can include an insulating interface (Optocoupler, Transformer).

[0084] The switch driver (530) can receive a switching signal generated by the controller (520) and drive the gate of the MOSFET or IGBT of the switching element (540).

[0085] The switching element (540) can perform an on / off operation according to a switching signal generated based on the residual voltage.

[0086] For example, the switching element (540) may be composed of a MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor) or an IGBT (Insulated Gate Bipolar Transistor).

[0087] The switching element (540) can be electrically connected to the resistance element (550) when the switching signal is on to allow current to flow through the resistance element (550), and can be electrically disconnected from the resistance element (550) when the switching signal is off to prevent current from flowing.

[0088] The resistance element (550) can discharge the residual voltage by applying current when the switching element (540) is turned on. For example, the resistance element (550) can be configured as a power resistor for discharge. The resistance element (550) can convert the discharge power according to the current applied when the switching element (540) is turned on into heat. The resistance element (550) can have a constant resistance value, and the resistance value can affect the amount of discharge power. Therefore, the controller (520) can calculate the reference power based on the resistance value of the resistance element (550) stored in the memory. In addition, when the resistance element (550) is a variable resistor, the controller (520) can calculate the reference power based on the current resistance value of the variable resistor.

[0089] FIGS. 6 to 8 are drawings for explaining the operation of an electric vehicle charging device according to an embodiment.

[0090] Referring to Fig. 6(a), it can be confirmed that as the residual voltage (horizontal axis) decreases, the duty cycle (vertical axis) increases. Also, referring to Fig. 6(b), it can be confirmed that as the residual voltage (vertical axis) decreases, the duty cycle (horizontal axis) increases.

[0091] The controller can increase the duty cycle so that the average current flowing through the resistive element increases as the residual voltage value is measured to be smaller. At this time, the duty cycle can have a value between 0 and 1. When the residual voltage decreases below a critical lower limit, the controller can no longer increase the duty cycle and fix the duty cycle to 1.

[0092] The controller can fix the duty cycle to 0 when the residual voltage is above the upper threshold value, and can adjust the duty cycle according to the residual voltage when the residual voltage is measured between the upper threshold value and the lower threshold value. When the residual voltage decreases below the lower threshold value, the controller can no longer increase the duty cycle and can fix the duty cycle to 1.

[0093] Referring to Fig. 7, the controller can calculate the average current based on the residual voltage. The controller can calculate the average current of Fig. 7(a) with a relatively high residual voltage to be lower than the average current of Fig. 7(b). The controller can adjust the duty cycle of Fig. 7(a) to be lower than the duty cycle of Fig. 7(b), thereby adjusting the average current of Fig. 7(a) with a relatively high residual voltage to be lower than the average current of Fig. 7(b).

[0094] Referring to Fig. 8, when the discharge power is applied to the resistive element at a constant current without PWM control, the residual voltage decreases rapidly, whereas referring to Fig. 9, it can be confirmed that the residual voltage decreases along a gentle curve as the discharge power is adjusted periodically by PWM control according to the embodiment. By controlling the residual voltage to decrease gently in this way, it is possible to prevent the power module from being damaged by high discharge power.

[0095] Referring to Fig. 10, the controller can control the switching element so that the amount of power discharged through the resistive element for each cycle is constant through PWM control using a switching signal. Fig. 10(a) shows the amount of power discharged through the resistive element, Fig. 10(b) shows the amount of current flowing through the resistive element, and Fig. 10(c) shows the voltage value applied to the resistive element. Here, the voltage value applied to the resistive element may mean the same value as the residual voltage value within a predetermined error range. The controller can perform PWM control so that the amount of power discharged for each cycle is the same by increasing the average current value flowing through the resistive element for one cycle as the residual voltage decreases through PWM control.

[0096] An electric vehicle charging device according to an embodiment measures the voltage of a power line in real time and calculates the root-mean-square current (I_RMS) flowing per cycle based on the measured voltage. The device then adjusts the on / off duty of a switch based on the remaining voltage based on the I_RMS value, and controls the current by gradually discharging power through a discharge resistor. This limits the instantaneous increase in current flowing to a component, preventing the component from having to handle power exceeding its specifications and enabling safer discharge.

[0097] The term '~ part' used in this embodiment means a software or hardware component such as an FPGA (field-programmable gate array) or an ASIC, and the '~ part' performs certain roles. However, the '~ part' is not limited to software or hardware. The '~ part' may be configured to be on an addressable storage medium and may be configured to play one or more controllers. Thus, as an example, the '~ part' includes components such as software components, object-oriented software components, class components, and task components, processes, functions, attributes, procedures, subroutines, segments of program code, drivers, firmware, microcode, circuits, data, databases, data structures, tables, arrays, and variables. The functionality provided within the components and '~ parts' may be combined into a smaller number of components and '~ parts' or further separated into additional components and '~ parts'. Additionally, components and '~parts' may be implemented to regenerate one or more CPUs within a device or secure multimedia card.

[0098] Although the present invention has been described above with reference to preferred embodiments thereof, it will be understood by those skilled in the art that various modifications and changes may be made to the present invention without departing from the spirit and scope of the present invention as set forth in the claims below.

Claims

1. AC-DC converter that converts AC power supplied from an AC power source into DC power; A DC-DC converter that converts the above DC power into a charging voltage for an electric vehicle battery; An output filter that transmits the charging voltage to the charging terminal of the electric vehicle battery; and An electric vehicle charging device comprising a discharge circuit unit including a voltage sensor that measures the residual voltage of the output filter at the end of charging of the electric vehicle battery, a switching element that performs an on-off operation according to a switching signal generated based on the residual voltage, and a resistance element that discharges the residual voltage by applying current when the switching element is operated in an on state.

2. In paragraph 1, An electric vehicle charging device, wherein the discharge circuit section further includes a controller that generates the switching signal by calculating the duty cycle of the switching element based on the residual voltage.

3. In paragraph 2, An electric vehicle charging device in which the controller calculates an average current flowing through the resistance element at preset cycles according to the residual voltage, and calculates the duty cycle based on the average current.

4. In paragraph 3, The above controller is an electric vehicle charging device that calculates the average current based on a preset reference power.

5. In paragraph 4, The above controller is an electric vehicle charging device that calculates the average current so that a constant amount of power is discharged through the resistance element at each preset cycle.

6. In paragraph 2, An electric vehicle charging device wherein the controller increases the duty cycle according to the amount of decrease in the residual voltage.

7. In paragraph 2, An electric vehicle charging device wherein the discharge circuit section further includes a switch driver that controls the on / off operation of the switching element according to the switching signal.

8. In paragraph 1, An electric vehicle charging device in which the above switching element and the above resistance element are connected in series.

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