Vehicle charging device

Abstract

We provide vehicle charging equipment. [Solution] The vehicle charging device includes an amplitude detection unit that detects the amplitude of the input grid voltage, a frequency detection unit that detects the frequency of the grid voltage, a PLL (Phase Locked Loop) unit that monitors the phase of the grid voltage, and a gain selection unit that inputs a coefficient calculated using the amplitude and frequency of the grid voltage to the PLL unit, wherein the amplitude detection unit and the frequency detection unit detect multiple points where the state of the grid voltage changes.

Description

[Technical Field]

[0001] This embodiment relates to a vehicle charging device. [Background technology]

[0002] As environmental problems caused by exhaust fumes from internal combustion engine vehicles worsen, the production of environmentally friendly electric vehicles is increasing. Recently, many countries have announced that they will gradually switch all their vehicles to environmentally friendly cars, and are reducing the production of internal combustion engine vehicles while increasing the production and sales of environmentally friendly vehicles such as electric vehicles.

[0003] Electric vehicles (EVs) are cars that primarily use battery power to drive a motor and operate using that power. A charger is necessary to recharge the battery, and since charging is repeatedly performed through the charger, the charger is a very important element for electric vehicles.

[0004] The aging of internal components in electric vehicle chargers, contraction and expansion due to temperature changes over the four seasons, and failure to check for faulty connections due to minute vibrations can lead to situations where chargers are operated without checking for these issues. This can result in high voltage arcing being applied to electric vehicle batteries due to malfunctions during operation, or the charger's operation being interrupted due to a charger malfunction. This directly leads to social losses. [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] This embodiment aims to provide a vehicle charging device with improved phase tracking performance and a vehicle charging device that can prevent circuit damage and malfunctions. [Means for solving the problem]

[0006] The vehicle charging device according to this embodiment includes an amplitude detection unit for detecting the magnitude of the grid voltage input to the vehicle charging device; a frequency detection unit for detecting the frequency of the grid voltage; a PLL (Phase Locked Loop) unit for monitoring the phase of the grid voltage; and a gain selection unit for inputting a coefficient calculated using the magnitude and frequency of the grid voltage to the PLL unit. The amplitude detection unit and the frequency detection unit detect a plurality of points where the state of the grid voltage changes.

[0007] The plurality of points where the state of the system voltage changes are points where the system voltage changes from an increasing direction to a decreasing direction or from a decreasing direction to an increasing direction, and the amplitude detection unit can detect the amplitude of the system voltage by taking the average of the voltages at the plurality of points.

[0008] The plurality of points where the state of the system voltage changes are points where the system voltage changes from an increasing direction to a decreasing direction or from a decreasing direction to an increasing direction, and the frequency detection unit can detect the frequency of the system voltage by averaging the periods of the plurality of points.

[0009] The PLL section includes a phase detection unit that detects the phase error between the phase of the system voltage and the phase of the voltage output from the PLL section; an LPF (Low Pass Filter) section that removes noise from the signal output from the phase detection unit; and a VCO (Voltage Controlled Oscillator) section that adjusts the voltage frequency of the signal output from the LPF. The gain selection unit can input the coefficients to the LPF section and the VCO section.

[0010] The LPF section includes a notch filter and an integrator, and the gain selection section can input the coefficients to the notch filter and the integrator.

[0011] The vehicle charging method according to this embodiment includes the steps of: detecting a plurality of points where the state of the grid voltage changes; detecting the magnitude and frequency of the grid voltage through the plurality of points; and inputting a coefficient calculated using the magnitude and frequency of the grid voltage to the PLL unit.

[0012] The multiple points where the state of the system voltage changes are points where the system voltage changes from an increasing direction to a decreasing direction or from a decreasing direction to an increasing direction, the magnitude of the system voltage can be detected through the average of the voltages at the multiple points, and the frequency of the system voltage can be detected through the average of the periods at the multiple points.

[0013] The PLL unit includes a phase detection unit that detects the phase error between the phase of the system voltage and the phase of the voltage output from the PLL unit; an LPF (Low Pass Filter) unit that removes noise from the signal output from the phase detection unit; and a VCO (Voltage Controlled Oscillator) unit that adjusts the voltage frequency of the signal output from the LPF. The step of inputting a coefficient calculated using the amplitude and frequency of the system voltage to the PLL unit can be performed by inputting the coefficient to the LPF unit and the VCO unit.

[0014] A vehicle charging device according to another embodiment of the present invention includes an amplitude detection unit for detecting the magnitude of a system voltage input to the vehicle charging device; a frequency detection unit for detecting the frequency of the system voltage; and a control unit that sets a plurality of normal operating ranges for the magnitude or frequency of the system voltage and determines whether the magnitude or frequency of the system voltage is within the normal operating range, wherein the amplitude detection unit and the frequency detection unit detect a plurality of points where the state of the system voltage changes.

[0015] The plurality of points where the state of the system voltage changes include points where the magnitude of the system voltage changes from an increasing direction to a decreasing direction, or from a decreasing direction to an increasing direction, and the amplitude detection unit can detect the magnitude of the system voltage by taking the average of the voltages at the plurality of points.

[0016] The plurality of points where the state of the system voltage changes includes a point where the magnitude of the system voltage changes from an increasing direction to a decreasing direction or from a decreasing direction to an increasing direction, and the frequency detection unit can detect the frequency of the system voltage through the average of the periods of the plurality of points.

[0017] The normal operating range of the magnitude of the system voltage includes a plurality of first ranges that do not overlap with each other, and the normal operating range of the frequency of the system voltage can include a plurality of second ranges that do not overlap with each other.

[0018] The amplitude detection unit detects the maximum value and the minimum value of the magnitude of the system voltage during a preset time, the frequency detection unit detects the maximum value and the minimum value of the frequency of the system voltage during the preset time, and the control unit can confirm which range among the plurality of first ranges the magnitude of the system voltage is in and which range among the plurality of second ranges the frequency of the system voltage is in.

[0019] When the magnitude of the system voltage corresponds to at least one of the plurality of first ranges and the frequency of the system voltage corresponds to at least one of the plurality of second ranges, the control unit can perform vehicle charging.

[0020] The control unit can confirm which range among the plurality of first ranges the magnitude of the system voltage is in and select a voltage level for overvoltage protection (OVP) or a voltage level for undervoltage protection (UVP).

[0021] A vehicle charging method according to another embodiment of the present invention includes the steps of detecting a plurality of points where the state of the system voltage changes; detecting the magnitude and frequency of the system voltage through the plurality of points; and determining whether the magnitude or frequency of the system voltage is within the normal operating range, respectively.

[0022] The multiple points where the state of the system voltage changes are points where the magnitude of the system voltage changes from an increasing direction to a decreasing direction, or from a decreasing direction to an increasing direction, the magnitude of the system voltage can be detected through the average of the voltages at the multiple points, and the frequency of the system voltage can be detected through the average of the periods at the multiple points.

[0023] The step of detecting the magnitude and frequency of the system voltage via the plurality of points includes detecting the maximum and minimum values ​​of the magnitude of the system voltage for a predetermined time, detecting the maximum and minimum values ​​of the frequency of the system voltage for a predetermined time, and determining whether the magnitude or frequency of the system voltage is within the normal operating range, by confirming which of a plurality of first ranges the magnitude of the system voltage is within, and confirming which of a plurality of second ranges the frequency of the system voltage is within, wherein the plurality of first ranges are normal operating ranges of the magnitude of the system voltage that do not overlap with each other, and the plurality of second ranges are normal operating ranges of the frequency of the system voltage that do not overlap with each other. [Effects of the Invention]

[0024] According to this embodiment, by adjusting the gain value optimized for the grid voltage, faster tracking performance can be ensured in grid phase tracking.

[0025] Furthermore, even if the grid phase changes due to faults or grid conditions, performance can be improved through rapid response, power factor enhancement, and reverse current prevention.

[0026] Furthermore, the system voltage input to the vehicle charging device can be predetermined, allowing for the selection of voltage levels for overvoltage protection (OVP) and undervoltage protection (UVP), as well as frequency levels for overfrequency protection (OFP) and underfrequency protection (UFP). This prevents circuit damage and malfunctions in the vehicle charging device. [Brief explanation of the drawing]

[0027] [Figure 1] This is a block diagram of a vehicle charging device according to this embodiment. [Figure 2] This diagram illustrates the operation of detecting the amplitude and frequency of the grid voltage of the vehicle charging device according to this embodiment. [Figure 3] This table explains the coefficients calculated using the amplitude and frequency of the vehicle charging device according to this embodiment. [Figure 4] This is a flowchart of the vehicle charging method according to this embodiment. [Figure 5] This figure illustrates the improvement effect of this embodiment on the vehicle charging system against disturbances. [Figure 6] This figure illustrates the improvement effect of this embodiment on the vehicle charging system against disturbances. [Figure 7] This figure illustrates the improvement effect of this embodiment on the vehicle charging system against disturbances. [Figure 8] This figure illustrates the improvement effect of this embodiment on the vehicle charging system against disturbances. [Figure 9] This diagram illustrates the comparison and explanation of the effects of existing vehicle charging devices and the vehicle charging device according to this embodiment. [Figure 10] This is a block diagram of a vehicle charging device according to another embodiment of the present invention. [Figure 11] This is a flowchart of a vehicle charging method according to another embodiment of the present invention. [Figure 12]This figure illustrates the range of the system voltage of a vehicle charging device according to another embodiment of the present invention. [Figure 13] This figure illustrates the frequency range of the system voltage of a vehicle charging device according to another embodiment of the present invention. [Modes for carrying out the invention]

[0028] Preferred embodiments of the present invention will be described in detail below with reference to the attached drawings. However, the technical concept of the present invention is not limited to the embodiments described, and can be embodied in various different forms. Within the scope of the technical concept of the present invention, one or more components between embodiments can be selectively combined or substituted for each other.

[0029] Furthermore, unless explicitly defined and described, terms used in the embodiments of the present invention (including technical and scientific terms) should be interpreted in the sense generally understood by a person skilled in the art to which the invention pertains. Commonly used terms, such as those defined in dictionaries, should be interpreted in consideration of their contextual meaning as described in the invention. In addition, terms used in the embodiments of the present invention are for illustrative purposes only and do not limit the invention.

[0030] In this specification, the singular form includes the plural form unless otherwise specified in the text, and when it is written as "A and / or at least one of B, C," it may include one or more of all possible combinations of A, B, and C. In addition, when describing the components of the embodiments of the present invention, terms such as first, second, A, B, (a), (b), etc. may be used. Such terms are used to distinguish a component from other components and are not limited by the nature, order, or sequence of the component in question.

[0031] Furthermore, when a component is described as “connected,” “joined,” “connected,” or “in contact” with another component, this includes not only cases where the component is directly connected, joined, or connected to the other component, but also cases where it is “connected,” “joined,” “connected,” or “in contact” with another component between it and the other component.

[0032] Furthermore, when described as being formed or positioned "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 positioned between the two components. Also, when expressed as "above or below," it can include not only an upward direction but also a downward direction relative to one component.

[0033] Figure 1 is a block diagram of the vehicle charging device according to this embodiment; Figure 2 is a diagram illustrating the operation of detecting the amplitude and frequency of the system voltage of the vehicle charging device according to this embodiment; Figure 3 is a table illustrating the coefficients calculated using the amplitude and frequency of the vehicle charging device according to this embodiment; Figure 4 is a flowchart of the vehicle charging method according to this embodiment; Figures 5 to 8 are diagrams illustrating the improvement effect of the vehicle charging device according to this embodiment against disturbances; and Figure 9 is a diagram illustrating the comparison of the effects of an existing vehicle charging device and the vehicle charging device according to this embodiment.

[0034] The vehicle charging device according to this embodiment can function as an on-board charger (OBC) by using the power of the AC power supply to charge the battery when connected to an AC power supply. The AC power supply input to the on-board charger has various system voltage amplitudes and frequencies depending on the country, and the on-board charger has been designed to operate with a fixed PLL tuning coefficient even when the magnitude of the frequency and voltage changes. However, this has the problem that errors in phase tracking occur when the system voltage sag (a phenomenon in which the voltage temporarily drops) or swell (a phenomenon in which the voltage temporarily rises), as well as when the phase and frequency change, occur, resulting in the generation of reverse inrush current. In addition, there are problems that can adversely affect PF (Power Factor) and THD (Total Harmonic Distortion), which are the main indicators of on-board charger performance, and can cause product damage.

[0035] The configuration included in the vehicle charging system of this embodiment, described below, can be applied to all power converters connected to grid voltage. For example, power converters may include EVSEs, server power supplies, ESSs, inverters, and converters.

[0036] The vehicle charging device according to this embodiment may include a monitoring unit 10 and a PLL unit 20. The monitoring unit 10 may include an amplitude detection unit 11, a frequency detection unit 12, and a gain selection unit 13. According to another embodiment, the vehicle charging device may not include a separate monitoring unit 10, and may include the amplitude detection unit 11, frequency detection unit 12, and gain selection unit 13 in separate configurations. The PLL unit 20 may include a phase detection unit 21, an LPF unit 22, and a VCO unit 25.

[0037] The amplitude detection unit 11 can detect the magnitude of the grid voltage input to the vehicle charging device.

[0038] The magnitude of the system voltage refers to the amplitude of the voltage. Voltage amplitude is a term that represents the maximum fluctuation range of an electrical signal, and in the case of AC voltage, amplitude can be defined as the distance from the reference line (OV) to the maximum or minimum value of the voltage waveform. System voltage (V=V) will be explained below. grid sin(θ g The magnitude or amplitude of )) is V grid It can mean that.

[0039] The frequency detection unit 12 can detect the frequency of the grid voltage input to the vehicle charging device. Voltage frequency is a term that represents how many times the voltage waveform is repeated over a certain period of time. If the time it takes for one cycle of the voltage waveform is called the period, then the voltage frequency can be defined as the reciprocal of the period.

[0040] The amplitude detection unit 11 and the frequency detection unit 12 can detect multiple points where the state of the grid voltage changes. These multiple points where the state of the grid voltage changes may be points where the grid voltage changes from an increasing direction (Up flag) to a decreasing direction (Down flag), or points where it changes from a decreasing direction to an increasing direction. The amplitude detection unit 11 can detect the magnitude of the grid voltage by averaging the voltages at the multiple points where the state of the grid voltage changes. The frequency detection unit 12 can detect the frequency of the grid voltage by averaging the periods at the multiple points where the state of the grid voltage changes.

[0041] Referring to Figure 2, it is possible to detect points where the state of the system voltage changes from increasing to decreasing (P1, P3) and points where it changes from decreasing to increasing (P2, P4). At this time, the amplitude detection unit 11 can calculate the average of the voltages from P1 to P4 to detect the magnitude of the system voltage, and the frequency detection unit 12 can calculate the period of the system voltage waveform by calculating the time required from P1 to P3 and the time required from P2 to P4, and can then convert this to its reciprocal to detect the frequency of the system voltage.

[0042] The gain selection unit 13 can input coefficients calculated using the magnitude and frequency of the system voltage to the PLL unit 20. The gain selection unit 13 can input the calculated coefficients to the LPF unit 22 and VCO unit 25 of the PLL unit 20. The gain selection unit 13 can input the calculated coefficients to the notch filter 23 and integrator 24 of the LPF unit 22, respectively. The operation by which the gain selection unit 13 calculates the coefficients using the magnitude and frequency of the system voltage will be explained in detail after the explanation of each component included in the PLL unit 20.

[0043] The Phase Locked Loop (PLL) section 20 can monitor the phase of the system voltage. The PLL section 20 is an electronic circuit used to synchronize the frequency and phase of the system voltage, and may include a phase detection section 21, an LPF section 22, and a VCO section 25.

[0044] The Phase Detect (PD) 21 can detect the phase error (ε) between the phase of the system voltage and the phase of the voltage output from the PLL unit 20. The Phase Detect (PD) 21 can convert the phase error (ε) into a voltage signal.

[0045] The LPF (Loop Filter) 22 can remove noise from the signal output from the phase detection unit 21. The LPF 22 can maintain an appropriate bandwidth, and the signal output from the LPF 22 can be used as a control signal for the VCO unit 25. The LPF 22 may include a notch filter 23 and an integrator 24. The notch filter 23 is a filter that selectively attenuates a specific frequency band and is mainly used to reduce frequency interference. The notch filter 23 can improve the quality of the output signal by removing interference and oscillations at specific frequencies. The integrator 24 can generate a voltage signal by accumulating the phase error (ε) over time.

[0046] The VCO section (Voltage Controlled Oscillator) 25 can adjust the voltage frequency of the signal output from the LPF section 22. The VCO section 25 can output a sine wave (sin(θ out )) and a systematic angle (θ out ). The systematic angle (θ out ) is an angle representing how much the frequency signal has moved during a specific time. When the PLL section 20 is stabilized, the difference between the systematic voltage input to the PLL section 20 and the systematic angle (θ out ) of the output signal of the VCO section 25 may become very small. The signal output from the VCO section 25 can be fed back to the phase detection section 21 again. The VCO section 25 can feed back a cosine wave (cos(θ out )) having a 90-degree phase difference from the sine wave (sin(θ out )) to the phase detection section 21.

[0047] Hereinafter, the operations of each component of the PLL section 20 and the process to which the coefficient calculated by the gain selection section 13 is applied will be described.

[0048] Assuming that a sine wave (sin(θ grid )) close to the systematic voltage (V = V g sin(θ out )) is output from the VCO section 25, the VCO section 25 feeds back a cosine wave (V´ = cos(θ out )) having a 90-degree phase difference to the phase detection section 21. The phase detection section 21 multiplies the systematic voltage (V = V grid sin(θ g )) and the cosine wave (V´ = cos(θ out )) to detect the phase error (ε).

[0049]

Number

[0050]

Number

[0051]

number

[0052] Linearizing the phase error (ε) in the above mathematical formula (3), it can be expressed by the following mathematical formula (4).

[0053]

number

[0054] The notch filter 23 is a filter that selectively attenuates a specific frequency band, and the transfer function of the notch filter 23 is given by the following mathematical equation (5).

[0055]

number

[0056] ζ p : Notch filter depth, ζ z : Notch filter width, ω g : G system frequency (cutoff frequency)

[0057] When the Tustin transform is used to convert the s-domain transfer function in the above mathematical equation (5) to a z-domain transfer function, we obtain the following mathematical equation (6).

[0058]

number

[0059] Here, the coefficients of mathematical formula (6) can be rearranged as shown in mathematical formulas (7) and (8) below. The coefficients X, Y, and Z of mathematical formula (8) can be calculated in the gain selection unit 13 through the magnitude and frequency of the system voltage.

[0060]

number

[0061]

number

[0062] In equation (8) above, Tsamp can be the control sampling time of the vehicle charging device. For example, the vehicle charging device can monitor the grid voltage every 10 kHz, in which case the sampling time can be 1 / 10000 sec. c1 can be the attenuation constant, and c2 can be the bandwidth constant.

[0063] Subsequently, when the signal output from the notch filter 23 is input to the integrator 24, the phase error (ε) can be accumulated over time to generate a voltage signal. The transfer function of the integrator 24 is given by the following mathematical equation (9).

[0064]

number

[0065] By using the Tustin transform to convert the s-domain transfer function to the z-domain transfer function in the above mathematical equation (9), it can be transformed into the following mathematical equation 10.

[0066]

number

[0067] When mathematical equation 10 is expressed as a discrete equation for digital computation, it becomes mathematical equation 11.

[0068]

number

[0069] Here, the coefficient of mathematical formula (9) can be rearranged as shown in mathematical formula 12 below. The coefficient of mathematical formula 12 is K. p , K l This can be calculated by the gain selection unit 13 through the magnitude and frequency of the system voltage.

[0070]

number

[0071] Subsequently, the VCO unit 25 can adjust the voltage frequency of the signal output from the LPF unit 22, and the VCO unit 25 adjusts the voltage input to the VCO unit 25 to a specific frequency ω ref It is possible to tune the range. In this case, the necessary coefficient ω ref The gain selection unit 13 selects the frequency ω of the system voltage. g It can be calculated through this. According to another embodiment, the reference frequency for tuning is ω in the VCO section 25. ref This may be the frequency of the system voltage detected by the frequency detection unit 12.

[0072] As described above, the coefficients input to the LPF section 22 and VCO section 25 of the PLL section 20 are pre-calculated by the gain selection section 13 through the magnitude and frequency of the system voltage and can be stored in the form of a lookup table as shown in Figure 3. In other words, when the amplitude detection section 11 and frequency detection section 12 of the monitoring section 10 detect the magnitude and frequency of the system voltage, the gain selection section 13 can input coefficients that match the magnitude and frequency of the system voltage to the PLL section 20.

[0073] The following describes each step of the vehicle charging method according to this embodiment with reference to Figure 4. Since the vehicle charging method according to this embodiment overlaps with the description of the vehicle charging device mentioned above, a detailed explanation will be omitted. Furthermore, the vehicle charging method according to this embodiment does not necessarily need to include all of the steps described below; some steps can be omitted, and some steps can be expressed as integrated steps.

[0074] In this embodiment of the vehicle charging method, the system voltage is input to the vehicle charging device (S1), and a charging start command (CMD) can be received (S2). Subsequently, the directionality (Flag) of the system voltage is checked, and the point where the state of the system voltage changes is checked (S3). The peak voltage at the point where the directionality of the system voltage changes (Edge) is saved (S4), and four peak voltages are collected (S5). Then, the average of the four peak voltages is calculated (S6), the frequency is calculated through the period of the four peak voltages (S7), and the magnitude and frequency of the system voltage are determined (S8). The coefficient (or gain) calculated from the magnitude and frequency of the system voltage is input to the PLL unit (S9).

[0075] The following explanation, using Figures 5 to 9, will describe the improvements made by the vehicle charging device and vehicle charging method according to this embodiment.

[0076] Referring to Figure 5, the grid voltage can experience unstable conditions such as (1) phase changes and distortion, (2) frequency changes, and (3) amplitude changes. When such grid voltage fluctuations occur, the vehicle charging system must quickly track the phase and supply power stably.

[0077] In the uppermost graphs shown in Figures 6 to 8, the waveform of the grid voltage (u / 220 / sqrt(2)) is shown as a green line, the waveform of the PLL output voltage (PLL50_SIN) when the frequency applied to the PLL is fixed at 50Hz is shown as a red line, the waveform of the PLL output voltage (PLL60_SIN) when the frequency applied to the PLL is fixed at 60Hz is shown as a blue line, and the waveform of the voltage output (fastPLL_SINOUT) when a coefficient calculated through the magnitude and frequency of the grid voltage is applied in the PLL section of the vehicle charging device according to this embodiment is shown as a yellow line.

[0078] Figure 6 shows that when a phase change or distortion occurs in the grid voltage, the yellow line follows the green line more quickly than the red and blue lines. Figure 7 shows that when a frequency change occurs in the grid voltage, the yellow line follows the green line more quickly than the red and blue lines. Figure 8 shows that when an amplitude change occurs in the grid voltage, the yellow line follows the green line more quickly than the red and blue lines. In other words, the vehicle charging device and vehicle charging method according to this embodiment can detect the magnitude and frequency of the grid voltage in real time, and by calculating and applying the coefficients to be applied to the PLL section, faster phase tracking performance can be ensured.

[0079] The upper graph in Figure 9 shows the waveform of the voltage output when the system voltage is input at 100Vac and 60Hz, and the output voltage is fixed at 220Vac and 60Hz during PLL operation. The lower graph shows the waveform of the voltage output from the PLL when the system voltage is input at 100Vac and 60Hz, and the coefficients optimized according to the magnitude and frequency of the system voltage are input to the PLL according to this embodiment. When comparing the portion where each voltage waveform zero-crosses in the area where theta value is 0 degrees, it can be confirmed that there is an improvement in phase tracking, as the error (gap) in the lower graph is reduced compared to the upper graph.

[0080] Figure 10 is a block diagram of a vehicle charging device according to another embodiment of the present invention, Figure 11 is a flowchart of a vehicle charging method according to another embodiment of the present invention, Figure 12 is a diagram illustrating the range of the system voltage of a vehicle charging device according to another embodiment of the present invention, and Figure 13 is a diagram illustrating the frequency range of the system voltage of a vehicle charging device according to another embodiment of the present invention.

[0081] Another embodiment of the present invention may be an on-board charger (OBC) that, when connected to an AC power source, uses the power of an AC power source to charge the battery. The AC power input to the on-board charger has various grid voltage amplitudes and frequencies depending on the country, and on-board chargers have been designed to operate regardless of the frequency and voltage magnitude. This is because, considering grid voltage sag (a phenomenon in which the voltage temporarily drops) and swell (a phenomenon in which the voltage temporarily rises), the on-board charger continues to operate even if the grid voltage is outside the acceptable range, which can lead to circuit damage.

[0082] A vehicle charging device according to another embodiment of the present invention includes a monitoring unit 10, which may include an amplitude detection unit 11, a frequency detection unit 12, and a control unit 14. According to another embodiment, the vehicle charging device may not include a separate monitoring unit 10, and may include the amplitude detection unit 11, the frequency detection unit 12, and the control unit 14 in separate configurations. The amplitude detection unit 11 and the frequency detection unit 12 according to another embodiment of the present invention are omitted here as they overlap with the explanation given with reference to Figures 1 and 2.

[0083] The control unit 14 can set multiple normal operating ranges for the magnitude or frequency of the system voltage and determine whether the magnitude or frequency of the system voltage is within the normal operating range. If the control unit 14 determines that the magnitude or frequency of the system voltage is not within the normal operating range, it can shut off the system voltage input or stop the operation of the vehicle charging device. The control unit 14 may be referred to as the Operation Level Setting unit.

[0084] The normal operating range of the grid voltage can include multiple first ranges that do not overlap with each other. Referring to Figure 12, while the allowable range of existing grid voltages is 85V to 265V, the normal operating range of the grid voltage in the vehicle charging device according to this embodiment can be subdivided by country or charging standard. For example, the multiple first ranges can include the ranges of 85V to 140V and 180V to 265V. The control unit 14 can control the vehicle charging device to operate only within one of the multiple first ranges. The control unit 14 can also control the vehicle charging device to operate within all of the multiple first ranges.

[0085] The normal operating range of the grid voltage frequency can include multiple second ranges that do not overlap with each other. Referring to Figure 13, while the allowable range of the existing grid voltage frequency is 45Hz to 65Hz, the normal operating range of the grid voltage frequency in the vehicle charging device according to this embodiment can be subdivided by country or charging standard. For example, the multiple second ranges can include the range of 45Hz to 55Hz and the range of 55Hz to 65Hz. The control unit 14 can control the vehicle charging device to operate only within one of the multiple second ranges. The control unit 14 can also control the vehicle charging device to operate within all of the multiple second ranges.

[0086] The control unit 14 can perform vehicle charging when the magnitude of the grid voltage falls within at least one of a plurality of first ranges, and when the frequency of the grid voltage falls within at least one of a plurality of second ranges.

[0087] The amplitude detection unit 11 can detect the maximum and minimum values ​​of the system voltage for a preset time. Here, the preset time may be a certain period of time before the start of charging by the vehicle charging device, a certain period of time after the start of charging by the vehicle charging device, or a certain period of time after a specific charge amount has been reached during charging. In other embodiments, the amplitude detection unit 11 can detect the maximum and minimum values ​​by monitoring the magnitude of the system voltage during vehicle charging and updating the values. This is merely illustrative and not limited to this.

[0088] The control unit 14 can determine which of several first ranges the magnitude of the grid voltage falls within. Based on this determination, the control unit 14 can select a voltage level for overvoltage protection (OVP) or undervoltage protection (UVP). This allows the control unit 14 to either cut off the grid voltage input or stop the operation of the vehicle charging device if it determines that the grid voltage input to the vehicle charging device falls outside the OVP or UVP range.

[0089] The frequency detection unit 12 can detect the maximum and minimum values ​​of the grid voltage frequency for a preset time. The control unit 14 can determine which of a plurality of second ranges the grid voltage frequency falls within. Here, the preset time may be a certain period of time before the start of charging by the vehicle charging device, a certain period of time after the start of charging by the vehicle charging device, or a certain period of time after a specific charge amount has been reached during charging. In other embodiments, the frequency detection unit 12 can detect the maximum and minimum values ​​by monitoring the grid voltage frequency during vehicle charging and updating the values. This is merely illustrative and not limited to this.

[0090] The control unit 14 can determine which of several second ranges the magnitude of the grid voltage falls within. Based on this determination, the control unit 14 can select a frequency level for over-frequency protection (OFP) or under-frequency protection (UFP). This allows the control unit 14 to either cut off the grid voltage input or stop the operation of the vehicle charging device if it determines that the grid voltage input to the vehicle charging device falls outside the OFP or UFP range.

[0091] The following describes each step of the vehicle charging method according to this embodiment with reference to Figure 11. Since the vehicle charging method according to this embodiment overlaps with the description of the vehicle charging device mentioned above, a detailed explanation will be omitted. Furthermore, the vehicle charging method according to this embodiment does not necessarily need to include all of the steps described below; some steps can be omitted, and some steps can be expressed as integrated steps.

[0092] In this embodiment, the vehicle charging method involves inputting a grid voltage to the vehicle charging device (S11) and receiving a charging start command (CMD) (S12). Subsequently, the directionality (Flag) of the grid voltage is checked, the point where the grid voltage state changes is checked (S13), the peak voltage is saved at the point where the directionality of the grid voltage changes (Edge) (S14), and four peak voltages are collected (S15). Then, the average of the four peak voltages is calculated (S16), the frequency is calculated through the period of the four peak voltages (S17), and the magnitude and frequency of the grid voltage are determined (S18). In addition, the range of OVP, UVP, OFP, and UFP levels is selected to prevent circuit damage to the vehicle charging device and ensure safe operation (S19).

[0093] Although embodiments of the present invention have been described above with reference to the attached drawings, those with ordinary skill in the art to which the present invention pertains should understand that the present invention can be implemented in other specific forms without altering the essential features of its technical idea. Therefore, the embodiments described above should be understood to be illustrative and not limiting in all respects.

Claims

1. Amplitude detection unit for detecting the magnitude of the grid voltage input to the vehicle charging device; A frequency detection unit for detecting the frequency of the aforementioned system voltage; A PLL (Phase Locked Loop) unit for monitoring the phase of the aforementioned system voltage; and The system includes a gain selection unit that inputs a coefficient calculated using the magnitude and frequency of the system voltage to the PLL unit. The amplitude detection unit and the frequency detection unit detect multiple points where the state of the grid voltage changes, in a vehicle charging device.

2. The multiple points where the state of the system voltage changes are points where the system voltage changes from an increasing direction to a decreasing direction, or points where it changes from a decreasing direction to an increasing direction. The vehicle charging device according to claim 1, wherein the amplitude detection unit detects the magnitude of the system voltage by averaging the voltages of the plurality of points.

3. The multiple points where the state of the system voltage changes are points where the system voltage changes from an increasing direction to a decreasing direction, or points where it changes from a decreasing direction to an increasing direction. The vehicle charging device according to claim 1, wherein the frequency detection unit detects the frequency of the system voltage by averaging the periods of the plurality of points.

4. The PLL section is, A phase detection unit that detects the phase error between the phase of the system voltage and the phase of the voltage output from the PLL unit; An LPF (Low Pass Filter) unit that removes noise from the signal output from the phase detection unit; and It includes a VCO (Voltage Controlled Oscillator) section that adjusts the voltage frequency of the signal output from the LPF, The vehicle charging device according to claim 1, wherein the gain selection unit inputs the coefficients to the LPF unit and the VCO unit.

5. The LPF section includes a notch filter and an integrator. The vehicle charging device according to claim 4, wherein the gain selection unit inputs the coefficients to the notch filter and the integrator.

6. Steps to detect multiple points where the state of the grid voltage changes; A step of detecting the magnitude and frequency of the system voltage via the plurality of points; and A vehicle charging method comprising the step of inputting a coefficient calculated using the magnitude and frequency of the aforementioned system voltage to a PLL unit.

7. The multiple points where the state of the system voltage changes are points where the system voltage changes from an increasing direction to a decreasing direction or from a decreasing direction to an increasing direction. The magnitude of the aforementioned system voltage is detected by averaging the voltages at the aforementioned multiple points. The vehicle charging method according to claim 6, wherein the frequency of the system voltage is detected through the average of the periods of the plurality of points.

8. The PLL section is, A phase detection unit that detects the phase error between the phase of the system voltage and the phase of the voltage output from the PLL unit; An LPF (Low Pass Filter) unit that removes noise from the signal output from the phase detection unit; and It includes a VCO (Voltage Controlled Oscillator) section that adjusts the voltage frequency of the signal output from the LPF, The vehicle charging method according to claim 6, wherein the step of inputting a coefficient calculated using the magnitude and frequency of the system voltage to the PLL unit is performed by inputting the coefficient to the LPF unit and the VCO unit.

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