Electric vehicle charging device

Abstract

According to an embodiment, there is provided an electric vehicle charging device 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 for an electric vehicle battery; an output filter that sends the charging voltage to a charging terminal of the electric vehicle battery; and a discharge circuit unit including: a voltage sensor that measures a residual voltage of the output filter at a point in time at which charging of the electric vehicle battery ends; a switching element that performs on-off operation in accordance with a switching signal generated based on the residual voltage; and a resistance element that discharges the residual voltage by being applied with a current when the switching element is operated in an on state.

Description

Technical Field

[0001] Embodiments of the present invention relate to a charging device for electric vehicles. Background Technology

[0002] After an electric vehicle has finished charging, during the discharge process of the residual power in the charging module, excess power flows through the components of the discharge circuit for a short period of time, causing the current flowing through the components to exceed their specifications. If the discharge switch is not controlled, the current from the residual power will flow to the discharge resistor to the maximum extent, which may cause the discharge resistor and other components to overheat or be damaged. To prevent this, increasing the component specifications can ensure durability; however, this leads to problems such as an increase in the number of components, an increase in component size, and an increase in the overall system cost. Therefore, a control system that can effectively perform discharge while preventing such component damage and overheating is needed. Summary of the Invention

[0003] Technical issues

[0004] The technical problem to be solved by the present invention is to provide an electric vehicle charging device that can safely remove residual power remaining in the battery and power module.

[0005] Technical solution

[0006] According to an embodiment, an electric vehicle charging device is provided, comprising: 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 for an electric vehicle battery; an output filter that transmits the charging voltage to the charging terminals of the electric vehicle battery; and a discharge circuit unit comprising: a voltage sensor that measures the residual voltage of the output filter at a point in time when charging of the electric vehicle battery is terminated; a switching element that performs an on-off operation based on a switching signal generated based on the residual voltage; and a resistive element to which current is applied when the switching element is in an on state to discharge the residual voltage.

[0007] The discharge circuit unit may further include a controller that calculates the duty cycle of the switching element based on the residual voltage to generate a switching signal.

[0008] The controller can calculate the average current flowing through the resistive element for each predetermined time period based on the residual voltage, and calculate the duty cycle based on the average current.

[0009] The controller can calculate the average current based on a predetermined reference power.

[0010] The controller can calculate the average current, so that a constant power is released through the resistive element for each predetermined time period.

[0011] The controller can increase the duty cycle based on the amount of reduction in residual voltage.

[0012] The discharge circuit unit may further include a switch driver that controls the on-off operation of the switching element according to a switching signal.

[0013] Switching elements and resistive elements can be connected in series.

[0014] Beneficial effects

[0015] The electric vehicle charging device according to the embodiment can prevent component damage during the discharge process and improve system reliability.

[0016] Furthermore, by effectively regulating the current flowing in the discharge circuit, it becomes unnecessary to use more components than required, thereby reducing the number of components and achieving the effect of reducing system size and cost.

[0017] Therefore, being able to safely discharge an electric vehicle after it has finished charging helps ensure safety during the disconnection process. Attached Figure Description

[0018] Figure 1 This is a conceptual diagram of an electric vehicle charging device according to an embodiment.

[0019] Figure 2 This is a block diagram illustrating the configuration of an electric vehicle charging device according to an embodiment.

[0020] Figure 3 This is a diagram illustrating the power module according to an embodiment.

[0021] Figure 4 and Figure 5 This is a conceptual diagram of a discharge circuit unit according to an embodiment.

[0022] Figure 6 to Figure 10 This is a diagram illustrating the operation of an electric vehicle charging device according to an embodiment. Detailed Implementation

[0023] Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0024] However, the technical concept of the present invention is not limited to the embodiments described herein, and can be implemented in various different forms; within the scope of the technical concept of the present invention, one or more components in the embodiments can be selectively combined or substituted.

[0025] Furthermore, unless otherwise explicitly and specifically defined and described, the terms (including technical and scientific terms) used in the embodiments of the present invention may be interpreted as meaning commonly understood by one of ordinary skill in the art to which the present invention pertains, and commonly used terms such as those defined in dictionaries may be interpreted in light of the contextual meaning of the relevant art.

[0026] Furthermore, the terminology used in the embodiments of the present invention is for illustrative purposes and is not intended to limit the invention.

[0027] In this specification, unless the context otherwise requires, the singular form may also include the plural form, and being described as “at least one (or one or more) of A, B, and C” may include one or more of all combinations that can be made using A, B, and C.

[0028] Furthermore, when describing the components of embodiments of the present invention, the terms first, second, A, B, (a) and (b) may be used.

[0029] These terms are used only to distinguish the corresponding components from other components, and the nature, order, or sequence of the corresponding components are not limited by such terms.

[0030] When a component is described as being “connected,” “coupled,” or “joined” to another component, the component can be “connected,” “coupled,” or “joined” not only directly to the other component, but also via another component existing between the component and the other component.

[0031] Furthermore, when described as forming or setting "above" or "below" each component, "above" or "below" includes not only cases where two components are in direct contact with each other, but also cases where one or more other components are formed or set between two components. Additionally, when expressed as "above" or "below," based on a component, it can include not only an upward direction but also a downward direction.

[0032] The embodiments will now be described in detail with reference to the accompanying drawings; regardless of the drawing numbers, the same or corresponding components are given the same reference numerals, and redundant descriptions will be omitted.

[0033] Figure 1 This is a conceptual diagram of an electric vehicle charging device according to an embodiment, and Figure 2 This is a block diagram illustrating the configuration of an electric vehicle charging device according to one embodiment.

[0034] Reference Figure 1 and Figure 2According to the embodiment, the electric vehicle charging device (100) is connected to a power outlet installed in a public place or public building, or an apartment or residence via a power outlet connection connector (C) formed on the outside, and supplies power from the power outlet to the electric vehicle (200) connected to the electric vehicle (200) connection connector (C) to charge the battery.

[0035] The electric vehicle charging device (100) receives charging control signals from the external charger operating system (300), switches the power connection between the power socket and the electric vehicle (200) according to the received control signals, and can supply AC commercial power applied through the power socket to the electric vehicle (200).

[0036] The 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).

[0037] In addition, the electric vehicle charging device (100) may have a connector (C) for connecting the electric vehicle (200).

[0038] The communication unit (110) can communicate with a user terminal (400) held by the driver of the electric vehicle (200) or the charger operating system (300) to send and receive data.

[0039] The power module (120) can supply commercial power from the power outlet to the electric vehicle (200) depending on the switching of the processor (130).

[0040] The power module (120) can be configured to include a rectifier, an AC-DC converter, a DC-DC converter, etc.; after the commercial power applied from the power outlet is rectified by the rectifier, the power can be converted into DC power used in the electric vehicle (200) by the AC-DC converter and the DC-DC converter.

[0041] When the electric vehicle (200) uses DC power, the power module (120) converts the AC power supplied from the power outlet into the DC power used in the electric vehicle (200) and supplies it; when the electric vehicle (200) uses AC power, power can be supplied directly to the electric vehicle (200) without specific power conversion.

[0042] The memory (160) stores programs and various data for controlling the charging device, and is able to load programs or read and write data according to the request of the processor (130).

[0043] The processor (130) is capable of performing overall control of the charging device. The processor (130) can be configured to execute programs and instructions stored in memory (160).

[0044] The processor (130) switches the power connection between the power module (120) and the electric vehicle (200) according to the charging station operating system or operating mode, and controls the power supply from the power module (120) to the electric vehicle (200) to perform charging.

[0045] 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 may additionally include a protection circuit that disconnects the connection between the power module (120) and the electric vehicle (200) in the event of overcurrent, overvoltage or overcharge.

[0046] 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 multiplying the current supplied to the electric vehicle (200) by the charging voltage.

[0047] When charging is complete, the processor (130) can send the calculated charging power to the user terminal through the communication unit (110), so that the user can verify the charging power based on the charging cost paid.

[0048] The display unit (140) is composed of LEDs, LCDs, etc., and is provided on the front surface of the electric vehicle charging device (100), and is capable of displaying information about the operating status of the electric vehicle charging device (100). In addition, the display unit (140) can be configured as a touch screen capable of input detection to receive user requests instructing the charging device.

[0049] The user interface unit (150) can be configured as a hardware-type interface provided at a predetermined location outside the charging device or a touchable software-type interface on the display unit (140) to receive various requests related to the operation of the charging device.

[0050] Figure 3 This is a diagram illustrating the power module according to an embodiment.

[0051] The charging device according to the embodiment is capable of receiving power from an AC power source (600) to perform the operation of charging an electric vehicle.

[0052] In this embodiment, the AC power source (600) is able to supply AC power to the electric vehicle charging system using electricity provided from the national grid or regional grid.

[0053] The AC power supply (600) can use various voltages such as 110V, 220V and 380V, and can supply AC power at a frequency of 50Hz or 60Hz.

[0054] The AC power supply (600) maintains the voltage and frequency, enabling the electric vehicle charging system to receive power stably, thereby meeting power quality (voltage, current THD) standards.

[0055] The AC power supply (600) may include an AC generator and a transformer. The AC generator generates an induced electromotive force through the interaction between magnetic flux (magnetic field) and coils (Faraday's Law), and the transformer transforms the voltage level to supply power suitable for transmission, distribution and end-user use.

[0056] Power from the AC power source (600) can be transmitted to the charging device via transmission lines (high voltage), distribution lines (medium voltage / low voltage), etc.

[0057] In addition, the AC power supply (600) may include a load management device that maintains the stability of the power grid and suppresses voltage fluctuations. The load management device can maintain a balance between power demand and supply in the power distribution unit, regulate power distribution during peak load periods, or disconnect part of the load in an emergency.

[0058] In addition, the AC power supply (600) can quickly cut off power in abnormal conditions such as short circuits, overloads and ground faults through the power protection system to prevent power surges caused by transient voltages or lightning.

[0059] The power module (120) is a key component that performs power conversion to efficiently charge the electric vehicle battery; electric vehicle charging devices require a complex power conversion process in terms of charging speed, efficiency, and stability. During this process, the power module (120) is able to convert the input power (AC or DC) into voltage and current suitable for the vehicle battery.

[0060] The power module (120) is capable of performing 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 unit (125).

[0061] The AC-DC converter (121) is a rectifier and is capable of converting AC power input to the charging device (100) into DC power. The AC-DC converter (121) can convert AC voltage to DC voltage using a diode bridge or an active rectifier circuit. Active rectification typically provides higher efficiency.

[0062] The PFC (Power Factor Correction) circuit (122) improves the power factor to increase the power efficiency in the power grid and reduce electromagnetic interference (EMI). The PFC circuit (122) aligns the waveform of the input current with the voltage waveform of the AC power to minimize power loss and impact on the power grid.

[0063] The DC-DC converter (123) is capable of converting rectified DC voltage to a voltage and current suitable for electric vehicle batteries. The DC-DC converter (123) can use a CLLC resonant converter, an LLC resonant converter, or a simple Buck converter to regulate the DC voltage. CLLC resonant converters offer particularly high efficiency and low EMI, making them frequently used in electric vehicle charging devices.

[0064] The output filter (124) removes the ripple voltage at the output of the DC-DC converter (123) and provides stable DC power, thereby improving battery protection and charging efficiency. The output filter (124) can reduce voltage ripple using LC filters (inductors and capacitors) to generate pure DC power.

[0065] The power module (120) can process electricity through the following steps: First, the AC power input to the charging device (100) can be converted into DC power in the AC-DC converter (121). During this process, a PFC circuit (122) can be used to improve the power factor. In this way, the use of power from the grid can be optimized and power loss can be reduced.

[0066] The rectified DC voltage can be converted into a voltage suitable for the electric vehicle battery in a DC-DC converter (123). In this step, the regulation of voltage and current is extremely important and can be adjusted in real time by the processor (130) according to the state of charge of the battery.

[0067] The converted DC voltage can be stabilized by an output filter (124). The output filter (124) removes voltage ripple and noise to supply DC power to the battery.

[0068] The processor (130) manages the entire charging process and can adjust the charging voltage and current according to the battery status. This prevents the battery from being overcharged, overheated, or otherwise damaged.

[0069] Through these processes, the power module (120) can convert AC or DC power into the power required by the electric vehicle battery with minimal loss. Furthermore, by supplying a constant and stable power to the electric vehicle battery, charging efficiency can be improved and battery life extended.

[0070] Furthermore, the heat generated during the charging process is effectively dissipated, maintaining module performance and stability. Additionally, overvoltage, overcurrent, and overheating are detected to protect the charging system and ensure safe charging.

[0071] Figure 4 and Figure 5 This is a conceptual diagram of a discharge circuit unit according to an embodiment. See also: Figure 4 and Figure 5 The discharge circuit unit (500) according to the embodiment may include a voltage sensor (510), a controller (520), a switch driver (530), a switching element (540), and a resistive element (550).

[0072] When a charging completion signal is detected, the discharge circuit unit (500) 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 resistive element (550).

[0073] A voltage sensor (510) is connected to both ends of an output filter that serves as the output terminal of a power module to measure the voltage of the power line.

[0074] When a charging completion signal is detected under the control of the controller (520), the voltage sensor (510) is able to measure the voltage of the power line of the output filter at the point when the charging of the electric vehicle battery ends, in order to calculate the residual voltage value.

[0075] The controller (520) can calculate the duty cycle of the switching element (540) based on the residual voltage to generate a switching signal.

[0076] In an embodiment, the duty cycle is a value representing the percentage of time during which the switching element (540) operates in the on state within a period of the switching signal, and the period may refer to the time required for the switching signal to complete a full on-off cycle.

[0077] The controller (520) converts the residual voltage measured by the voltage sensor (510) into digital data and can calculate the average current based on the current residual voltage. When the residual voltage is equal to or greater than a predetermined value, the controller (520) determines that discharge is required and is able to generate a switching signal to control the operation of the switching element (540) to discharge.

[0078] For example, the controller (520) can calculate the average current flowing through the resistive element (550) for each predetermined time period based on the residual voltage, and calculate the duty cycle based on the average current. For example, the controller (520) can calculate the average current based on a predetermined reference power.

[0079] At this time, the controller (520) is able to calculate the average current, so that a constant power is released through the resistive element (550) for each predetermined period.

[0080] In addition, the controller (520) can increase the duty cycle according to the amount of reduction in the residual voltage.

[0081] The controller (520) can calculate the discharge power for discharging through the resistive element (550) for each predetermined time period based on the residual voltage. At this time, the controller (520) can calculate the discharge power so as not to exceed a predetermined reference power. Here, the reference power may refer to a pre-set power value such that the components of the power module are not damaged by the power released during a time period. That is, since the components of the power module may be damaged if discharged at a power exceeding the reference power, the controller (520) can calculate the discharge power such that the discharge is equal to or less than the reference power.

[0082] The controller (520) can calculate the average current based on the discharge power. The average current can be defined as the amount of current required to output the discharge power through the resistive element (550) during a given period. Since power is proportional to current, the controller (520) increases the current flowing through the resistive element (550) as the residual voltage decreases to maintain a constant discharge power for each period. That is, the controller (520) can calculate the average current for each period such that the current flowing through the resistive element (550) increases as the residual voltage decreases. Therefore, the average current for each period can be calculated as inversely proportional to the residual voltage.

[0083] 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 resistive element (550) for each time period converges to the average current. The controller (520) calculates that the duty cycle increases as the average current increases and decreases as the average current decreases. That is, in time periods when the measured residual voltage is small and the calculated average current is high, the controller (520) increases the time when the switching element (540) operates in the on state; in time periods when the measured residual voltage is large and the calculated average current is low, the controller (520) can increase the time when the switching element (540) operates in the off state.

[0084] The controller (520) can generate a switching signal based on the duty cycle. The controller (520) can output waveform data for the duration of the switching element (540) operating in the on state and the duration of its operating in the off state, according to the duty cycle. That is, by using PWM control of the switching signal, the controller (520) can control the switching element (540) so that the amount of power released through the resistive element (550) remains constant for each time period.

[0085] The switch driver (530) can control the on-off operation of the switching element (540) according to the switching signal. For example, the switch driver (530) can be composed of a MOSFET / IGBT driver and can include an isolation interface (optocoupler, transformer).

[0086] The switch driver (530) receives the switching signal generated by the controller (520) and is used to drive the gate of the MOSFET or IGBT of the switching element (540).

[0087] The switching element (540) can perform on-off operations based on a switching signal generated based on the residual voltage.

[0088] For example, the switching element (540) can be composed of a MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor) or an IGBT (Insulated Gate Bipolar Transistor).

[0089] When the switch signal is ON, the switch element (540) is connected to the resistor element (550) to allow current to flow through the resistor element (550); when the switch signal is OFF, the switch element (540) is electrically disconnected from the resistor element (550) to prevent current from flowing.

[0090] When the switching element (540) operates in the ON state to discharge residual voltage, the resistive element (550) receives current. For example, the resistive element (550) can be composed of a power resistor for discharge. When the switching element (540) is operated ON, the resistive element (550) is able to convert discharge power into heat according to the applied current. The resistive 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 a reference power based on the resistance value of the resistive element (550) stored in the memory. Furthermore, when the resistive element (550) is a variable resistor, the controller (520) can calculate the reference power based on the current resistance value of the variable resistor.

[0091] Figure 6 to Figure 10 This is a diagram illustrating the operation of an electric vehicle charging device according to an embodiment.

[0092] Referring to Figure 6(a), it can be seen that as the residual voltage on the horizontal axis decreases, the duty cycle on the vertical axis increases. Referring to Figure 6(b), it can be seen that as the residual voltage on the vertical axis decreases, the duty cycle on the horizontal axis increases.

[0093] The controller can increase the duty cycle, causing the average current flowing through the resistive element to increase as the measured residual voltage decreases. In this case, the duty cycle can have a value between 0 and 1. When the residual voltage drops to or below the lower threshold limit, the controller cannot further increase the duty cycle and can fix it at 1.

[0094] When the residual voltage is equal to or greater than the upper threshold limit, the controller fixes the duty cycle at 0. When the measured residual voltage is between the upper and lower threshold limits, it can adjust the duty cycle according to the residual voltage. When the residual voltage drops to equal to or less than the lower threshold limit, the controller cannot further increase the duty cycle and can fix the duty cycle at 1.

[0095] Referring to Figure 7, the controller can calculate the average current based on the residual voltage. The controller is able to calculate the average current in Figure 7(a), where the residual voltage is relatively high, as lower than the average current in Figure 7(b). By adjusting the duty cycle in Figure 7(a) to be less than the duty cycle in Figure 7(b), the controller is able to adjust the average current in Figure 7(a), where the residual voltage is relatively high, to be lower than the average current in Figure 7(b).

[0096] Reference Figure 8 Without PWM control, when a constant current is applied to the resistive element to discharge power, the residual voltage decreases rapidly; on the other hand, referring to Figure 9 Since the discharge power is adjusted to a constant level for each time period using PWM control according to the embodiment, it can be confirmed that the residual voltage decreases along a smooth curve. By controlling the residual voltage to decrease smoothly in this way, damage to the components of the power module due to high discharge power can be prevented.

[0097] Reference Figure 10 The controller can control the switching elements by using PWM control of the switching signal, so that the power released through the resistive element remains constant for each time period. Figure 10 (a) is the power released through the resistive element. Figure 10 (b) is the amount of current flowing through the resistive element, and Figure 10(c) is the voltage value applied to the resistive element. Here, the voltage value applied to the resistive element can mean a value equal to the residual voltage value within a predetermined error range. The controller can perform PWM control by increasing the average current value flowing through the resistive element during a time period as the residual voltage decreases through PWM control, thereby keeping the amount of discharge power the same for each time period.

[0098] According to the embodiment, the electric vehicle charging device measures the voltage of the power line in real time and calculates the RMS current (I_RMS) flowing in each time period based on the measured voltage. Then, based on the I_RMS value, the on / off duty cycle of the switch is adjusted according to the residual voltage, and the current can be controlled by gradually discharging the power through a discharge resistor. This limits the rate of increase of the instantaneous current flowing through the component, preventing the component from having to handle power exceeding specifications, thereby enabling safer discharge.

[0099] The term "~unit" (or "~section") used in this embodiment refers to software or hardware components such as FPGAs (Field-Programmable Gate Arrays) or ASICs, and "~units" perform a specific function. However, "~units" are not limited to software or hardware. "~units" can be configured to reside in addressable storage media or to execute one or more controllers. Thus, as an example, "~units" include components such as software components, object-oriented software components, class components, and task components; processes; functions; attributes; procedures; subroutines; program code segments; drivers; firmware; microcode; circuits; data; databases; data structures; tables; arrays; and variables. The functionality provided in components and "~units" can be combined into a smaller number of components and "~units," or can be further separated into additional components and "~units." Furthermore, components and "~units" can be implemented as one or more CPUs within an execution device or secure multimedia card.

[0100] Although the invention has been described above with reference to preferred embodiments, those skilled in the art will understand that various modifications and alterations can be made to the invention without departing from the spirit and scope of the invention as set forth in the appended claims.

Claims

1. An electric vehicle charging device, comprising: An AC-DC converter that converts AC power supplied by an AC power source into DC power; A DC-DC converter that converts the DC power into the charging voltage of the electric vehicle battery; An output filter that sends the charging voltage to the charging terminal of the electric vehicle battery; as well as A discharge circuit unit, comprising: a voltage sensor that measures the residual voltage of the output filter at a point in time when charging of the electric vehicle battery is terminated; a switching element that performs an on-off operation based on a switching signal generated based on the residual voltage; and a resistive element to which current is applied when the switching element is in an on state to discharge the residual voltage.

2. The electric vehicle charging device according to claim 1, in, The discharge circuit unit further includes a controller that calculates the duty cycle of the switching element based on the residual voltage to generate the switching signal.

3. The electric vehicle charging device according to claim 2, in, The controller calculates the average current flowing through the resistive element for each predetermined time period based on the residual voltage, and calculates the duty cycle based on the average current.

4. The electric vehicle charging device according to claim 3, in, The controller calculates the average current based on a predetermined reference power.

5. The electric vehicle charging device according to claim 4, in, The controller calculates the average current so that a constant power is released through the resistive element for each predetermined time period.

6. The electric vehicle charging device according to claim 2, in, The controller increases the duty cycle based on the amount of reduction in the residual voltage.

7. The electric vehicle charging device according to claim 2, in, The discharge circuit unit further includes a switch driver, which controls the on-off operation of the switching element according to the switch signal.

8. The electric vehicle charging device according to claim 1, in, The switching element and the resistive element are connected in series.

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