Power conversion device

Abstract

A power conversion device according to an embodiment of the present invention comprises: an input unit for receiving input power; a power conversion unit for converting the input power; an output unit for outputting power to a battery; a diode connected between the power conversion unit and the output unit; and a control unit that uses the voltages of the front and rear ends of the diode to control an output current output to the output unit.

Description

power converter

[0001] The present invention relates to a power converter, and more specifically, to a power converter capable of zero-current output and an electric vehicle charging device.

[0002] Fast chargers for electric vehicles configure power modules with capacities of tens of kW in parallel to support high-speed charging of several hundred kW, thereby outputting a large amount of power. When connected to an electric vehicle, the power modules receive AC power from the grid and output DC power to charge the vehicle's battery.

[0003] Significant heat is generated during power conversion within the power module. The resonant inductor in the resonant circuit constituting the power module is one of the heat-generating components; therefore, to ensure product reliability, technology capable of enhancing the heat dissipation effect of the resonant inductor is required.

[0004] The technical problem that the present invention aims to solve is to provide a power converter capable of zero current output and an electric vehicle charging device.

[0005] To solve the above technical problem, a power conversion device according to one embodiment of the present invention includes: an input unit that receives an input power source; a power conversion unit that converts the input power source; an output unit that outputs power to a battery; a diode connected between the power conversion unit and the output unit; and a control unit that controls an output current output to the output unit using the voltages at the front and rear ends of the diode.

[0006] In addition, the control unit can control the power converter such that the first voltage, which is the voltage at the front end of the diode, is lower than the second voltage, which is the voltage at the rear end of the diode, thereby making the output current 0 A.

[0007] In addition, the control unit can control the power converter such that the value obtained by subtracting the threshold voltage of the diode from the first voltage, which is the voltage at the front end of the diode, is lower than the second voltage, which is the voltage at the rear end of the diode.

[0008] In addition, the control unit can control the value obtained by subtracting the first voltage, which is the voltage at the front of the diode, from the second voltage, which is the voltage at the rear of the diode, so that it is lower than the breakdown voltage of the diode.

[0009] In addition, the voltage at the rear end of the diode can correspond to the voltage of the battery.

[0010] In addition, the anode of the diode may be connected to the power converter, and the cathode may be connected to the output unit.

[0011] Additionally, it may include a first output voltage measuring unit for measuring the voltage at the front end of the diode; and a second output voltage measuring unit for measuring the voltage at the rear end of the diode.

[0012] In addition, it may include an output current measuring unit for measuring the output current of the above output unit.

[0013] In addition, the above battery may include an electric vehicle battery.

[0014] To solve the above technical problem, an electric vehicle charging device according to one embodiment of the present invention comprises: an input unit that receives an input power source; a power conversion unit that converts the input power source; an output unit that outputs power to an electric vehicle battery; a diode connected between the power conversion unit and the output unit; and a control unit that controls an output current output to the output unit using the voltages at the front and rear ends of the diode.

[0015] According to embodiments of the present invention, zero current output is possible upon request of an electric vehicle.

[0016] FIG. 1 illustrates a power conversion device according to one embodiment of the present invention.

[0017] FIG. 2 is a block diagram of a power conversion device according to an embodiment of the present invention.

[0018] FIG. 3 is a circuit implementation example of a power conversion device according to an embodiment of the present invention.

[0019] FIGS. 4 and FIGS. 5 are drawings for explaining the operation of a power converter according to an embodiment of the present invention.

[0020] FIG. 6 is a block diagram of an electric vehicle charging device according to an embodiment of the present invention.

[0021] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the attached drawings.

[0022] However, the technical concept of the present invention is not limited to some of the described embodiments but can be implemented in various different forms, and within the scope of the technical concept of the present invention, one or more of the components among the embodiments may be selectively combined or substituted.

[0023] In addition, terms used in the embodiments of the present invention (including technical and scientific terms) may be interpreted in a meaning that is generally understood by those skilled in the art to which the present invention belongs, unless explicitly and specifically defined otherwise. Terms that are commonly used, such as terms defined in advance, may be interpreted in consideration of their meaning in the context of the relevant technology.

[0024] Furthermore, the terms used in the embodiments of the present invention are for the purpose of describing the embodiments and are not intended to limit the present invention.

[0025] In this specification, the singular form may include the plural form unless specifically stated otherwise in the text, and when described as "at least one of A and B and C (or more than one)," it may include one or more of all combinations that can be formed from A, B, and C.

[0026] In addition, terms such as first, second, A, B, (a), (b), etc., may be used when describing the components of the embodiments of the present invention. These terms are used merely to distinguish the components from other components and are not intended to limit the essence, order, or sequence of the components.

[0027] And, where it is stated that a component is 'connected', 'combined', or 'connected' to another component, this may include not only cases where the component is directly 'connected', 'combined', or 'connected' to the other component, but also cases where it is 'connected', 'combined', or 'connected' due to another component located between the component and the other component.

[0028] Furthermore, when described as being formed or placed "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 placed between the two components. Additionally, when expressed as "above" or "below," it may include the meaning of a downward direction as well as an upward direction relative to a single component.

[0029] FIG. 1 illustrates a power conversion device according to an embodiment of the present invention. A power conversion device (100) according to an embodiment of the present invention is composed of an input unit (110), a power conversion unit (120), an output unit (140), a diode (130), and a control unit (150), and may include a first output voltage measuring unit (160), a second output voltage measuring unit (170), and an output current measuring unit (180).

[0030] A power converter (100) according to an embodiment of the present invention may be a power converter for an electric vehicle charging device. Here, the power converter (100) may be a power module for an electric vehicle charging device. The power module may receive AC power from a grid (50 / 60Hz), convert it into DC power for charging an electric vehicle battery, and output it. Alternatively, it may receive DC power from an energy storage system (ESS), convert it into DC power for charging a battery, and output it. It may receive power from an external power source, such as a solar power generation module. The power module may include an AC-DC rectifier and a DC-DC converter, and the power converter (100) according to an embodiment of the present invention may include an isolated DC-DC converter or a non-isolated converter. Among isolated DC-DC converters, it may include a Phase Shift Full Bridge (PSFB) converter, a Resonant LLC converter, a CLLC resonant converter, and a Dual Active Bridge (DAB) converter. Non-isolated DC-DC converters may include buck converters, boost converters, and buck-boost converters.

[0031] The input unit (110) receives power from the input power source (210), and the power conversion unit (120) converts the input power source and outputs it.

[0032] The power conversion unit (120) includes one or more switching elements and can convert and output voltage according to the switching operation of the switching elements. The power conversion unit (120) may include an isolated DC-DC converter or a non-isolated converter. Among the isolated DC-DC converters, it may include a PSFB converter, an LLC resonant converter, a CLLC resonant converter, and a DAB converter. Among the non-isolated DC-DC converters, it may include a buck converter, a boost converter, and a buck-boost converter.

[0033] The output unit (140) can output power converted by the power conversion unit (120) to the battery (220). The battery (220) may be an electric vehicle battery.

[0034] A diode (130) may be connected between the power conversion unit (120) and the output unit (140). The diode (130) may be connected such that its anode is connected to the power conversion unit (120) and its cathode is connected to the output unit (140). That is, the direction from the power conversion unit (120) to the output unit (140) is the forward direction, and the opposite direction is the reverse direction.

[0035] The control unit (150) controls the output current output to the output unit (140) using the voltages at the front and rear ends of the diode (130). The control unit (150) can control the power conversion unit (120) to convert the input power and can control the voltage of the power output from the power conversion unit (120).

[0036] The control unit (150) can receive a charging request from the battery management device (BMS) of the battery (220) or, if the battery (220) is an electric vehicle battery, control the power conversion unit (120).

[0037] When a charging request is received from an electric vehicle, the control unit (150) can control the output voltage, output current, output power, frequency, etc., according to the request. The electric vehicle may request fast charging or slow charging, and the control unit (150) can control the charging current accordingly. In addition, among the operations requested by the electric vehicle, a 'zero current' or 'no load' condition in which the current input to the battery is "0 A" may be included. When a zero current output of 0 A is requested from the electric vehicle, the control unit (150) can control the power conversion unit (120) to control the output current output to the output unit (140) to 0 A.

[0038] The control unit (150) can control the power converter (120) so that the first voltage, which is the voltage at the front end of the diode (130), is lower than the second voltage, which is the voltage at the rear end of the diode (130), thereby making the output current 0 A. The control unit (150) can lower the gain of the power converter (120) to lower the output voltage, thereby controlling the first voltage, which is the voltage at the front end of the diode (130), to be lower than the second voltage, which is the voltage at the rear end of the diode (130).

[0039] An output current of 0 A means that no current flows to the output section (140), so no current should flow to the output section (130). To this end, the control section (150) can control the power conversion section (120) such that the value obtained by subtracting the threshold voltage of the diode (130) from the first voltage, which is the voltage at the front of the diode (130), is lower than the second voltage, which is the voltage at the output of the diode (130). As shown in FIG. 5, the diode (130) has a characteristic of having a threshold voltage, and current flows only when there is a potential difference greater than the threshold voltage in the forward direction. Since the diode is driven in the forward direction above the threshold voltage, the threshold voltage can be called the turn-on voltage. That is, when the value obtained by subtracting the threshold voltage of the diode (130) from the first voltage, which is the voltage at the front end of the diode (130), is lower than the second voltage, which is the voltage at the rear end of the diode (130), the diode (130) does not operate in the forward direction, so no current flows to the output section (140), and a current of 0 A can be achieved.

[0040] The control unit (150) can control the diode (130) such that the value obtained by subtracting the first voltage at the front end of the diode (130) from the second voltage at the rear end of the diode (130) is lower than the breakdown voltage of the diode (130). As shown in FIG. 5, the diode (130) has a breakdown voltage other than the threshold voltage. When a reverse potential difference greater than the breakdown voltage is applied, current flows in the reverse direction. That is, since the diode is driven in the reverse direction below the breakdown voltage, the diode can be controlled so that the value obtained by subtracting the first voltage at the front end of the diode (130) from the second voltage at the rear end of the diode (130) is lower than the breakdown voltage of the diode (130), thereby preventing current from flowing in the reverse direction.

[0041] That is, the control unit (150) can control such that the value obtained by subtracting the threshold voltage of the diode (130) from the first voltage at the front end of the diode (130) is lower than the second voltage at the rear end of the diode (130), and the value obtained by subtracting the first voltage at the front end of the diode (130) from the second voltage at the rear end of the diode (130) is lower than the breakdown voltage of the diode (130).

[0042] The first voltage, which is the voltage at the front end of the diode (130), corresponds to the output voltage of the power conversion unit (120), and the second voltage, which is the voltage at the rear end of the diode (130), can correspond to the voltage of the battery (220).

[0043] The control unit (150) can receive the first voltage and the second voltage from the first output voltage measuring unit (160) and the second output voltage measuring unit (170) that measure the voltages of the front and rear ends of the diode (130).

[0044] The first output voltage measuring unit (160) can measure the voltage at the front end of the diode (130), and the second output voltage measuring unit (170) can measure the voltage at the rear end of the diode (130). As shown in FIG. 3, the first output voltage measuring unit (160) and the second output voltage measuring unit (170) can measure the voltage between the (+) power line and the (-) power line through a comparator and can be implemented as a voltage sensor.

[0045] Additionally, it may include an output current measuring unit (180) for measuring the output current of the output unit (140). The control unit (150) can check whether the output current becomes 0 A by using the measured output current. Additionally, it can monitor the output power by measuring the output voltage, which is a second voltage, and the output current.

[0046] In addition, an input voltage measuring unit (not shown) and an input current measuring unit (not shown) are included between the input unit (110) and the power conversion unit (120) to monitor information of the input power supply.

[0047] According to the current required by the electric vehicle, the control unit (150) controls the power converter, and at this time, the battery voltage, the power converter output voltage, the diode state, and the output current may operate as shown in FIG. 4. Here, the power converter output voltage may be a first voltage which is the voltage at the front end of the diode (130), and the battery voltage may be a second voltage which is the voltage at the rear end of the diode (130).

[0048] State 1 is a state in which a large current is requested from the electric vehicle to rapidly charge the electric vehicle battery. At this time, the output voltage of the power converter is higher than the battery voltage, so that the diode conducts in the forward direction, and current is output from the power converter (120) to the battery (220), thereby allowing charging of the battery (220). The power converter (120) can generate an output voltage higher than the battery voltage to form a forward bias on the diode. At this time, it can generate a voltage of approximately 1V higher than the threshold voltage of the diode (e.g., 0.7V).

[0049] State 2 is a state in which the electric vehicle battery is charged with low power as the current requested by the electric vehicle is reduced, and the output voltage of the power converter is still higher than the battery voltage, so the diode conducts and current is output to the battery (220), allowing the battery (220) to be charged. The power converter (120) can generate an output voltage higher than the battery voltage to form a forward bias on the diode (130).

[0050] State 3 is a state where the electric vehicle requests '0 A' and the electric vehicle battery is not charged. As a result, the output voltage of the power converter is lowered, the diode does not conduct, and current is not output from the power converter (120) to the battery (220), so charging may not occur. The power converter (120) can generate an output voltage lower than the battery voltage by forming a reverse bias on the diode (130). The power converter (120) can generate an output voltage such that the value obtained by subtracting the threshold voltage of the diode (130) from the output voltage of the power converter is lower than the battery voltage.

[0051] FIG. 6 is a block diagram of an electric vehicle charging device according to an embodiment of the present invention. The detailed description of each component corresponds to the detailed description of the components in FIG. 1 to 5, so redundant descriptions will be omitted below. The electric vehicle charging device (1000) according to an embodiment of the present invention may include a power module which is a plurality of power conversion devices (100, 200, 300), and each power conversion device may receive power from an input power source (210), convert it, and charge an electric vehicle battery (220). At this time, each power conversion device may include an input unit that receives the input power source, a power conversion unit that converts the input power source, an output unit that outputs power to the battery, a diode connected between the power conversion unit and the output unit, and a control unit that controls the output current output to the output unit using the voltages at the front and rear ends of the diode. The control unit can control the power converter so that the first voltage, which is the voltage at the front end of the diode, is lower than the second voltage, which is the voltage at the rear end of the diode, thereby making the output current 0 A, and can control the power converter so that the value obtained by subtracting the threshold voltage of the diode from the first voltage, which is the voltage at the front end of the diode, is lower than the second voltage, which is the voltage at the rear end of the diode.

[0052] Each power converter can individually control the output current to 0 A, and if a malfunction occurs in a specific power converter, the output current of that power converter can be controlled to 0 A to enable safe charging of the electric vehicle battery.

[0053] Those skilled in the art related to the embodiments described above will understand that they may be implemented in modified forms without departing from the essential characteristics of the description. Therefore, the disclosed methods should be considered in an illustrative rather than a restrictive sense. The scope of the invention is defined by the claims, not by the foregoing description, and all variations within the scope of equivalence should be interpreted as being included in the invention.

Claims

1. Input section receiving input power; A power conversion unit that converts the above input power; Output unit that outputs power from a battery; A diode connected between the power conversion unit and the output unit; and A power converter comprising a control unit that controls the output current output to the output unit using the voltages at the front and rear ends of the diode.

2. In Paragraph 1, The above control unit is, A power converter that controls the power converter so that the first voltage, which is the voltage at the front end of the diode, is lower than the second voltage, which is the voltage at the rear end of the diode, thereby making the output current 0 A.

3. In Paragraph 1, The above control unit is, A power converter that controls the power converter such that the value obtained by subtracting the threshold voltage of the diode from the first voltage, which is the voltage at the front end of the diode, is lower than the second voltage, which is the voltage at the rear end of the diode.

4. In Paragraph 1, The above control unit is, A power converter that controls the value obtained by subtracting the first voltage, which is the voltage at the front of the diode, from the second voltage, which is the voltage at the rear of the diode, so that it is lower than the breakdown voltage of the diode.

5. In Paragraph 1, The voltage at the rear end of the above diode is a power converter corresponding to the voltage of the above battery.

6. In Paragraph 1, The above diode is, A power converter in which the anode is connected to the power converter and the cathode is connected to the output unit.

7. In Paragraph 1, A first output voltage measuring unit for measuring the voltage across the diode; and A power converter comprising a second output voltage measuring unit for measuring the voltage after the diode.

8. In Paragraph 1, A power converter comprising an output current measuring unit for measuring the output current of the above-mentioned output unit.

9. In Paragraph 1, The above battery is a power conversion device including an electric vehicle battery.

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