Power conversion device

Abstract

A power conversion device according to one embodiment of the present disclosure includes: a power conversion unit that, when connected to an AC power supply, converts AC power into DC power to charge a battery; and an initial charging unit that is connected to the secondary output side of the power conversion unit and that initially charges the load-side capacitor, in which the output terminal of the power conversion unit is connected to the battery and the load-side capacitor.

Description

Technical Field

[0001] The present disclosure relates to a power conversion device, and more particularly, to a power conversion device capable of initial charging and an automatic battery system including the power conversion device. Background Art

[0002] In order to convert the battery power into power suitable for the internal loads of the vehicle, voltage conversion is required. The battery voltage may be in the range of 400V to 800V, and the rated voltage of the internal loads of the vehicle may be 12V.

[0003] When operating the switch to connect the battery with the load, if there is a voltage difference across the switch, surge voltage and current may occur due to the parasitic inductance of the load-side capacitor and the connecting wire, which may cause damage to internal components. To solve this problem, the load-side capacitor is initially charged by connecting a relay and a resistor.

[0004] However, there is a problem in that separate relays and resistors are required, which increases cost and area. Summary of the invention

[0005] Technical issues

[0006] The technical problem to be solved by the present disclosure is to provide a power conversion device capable of initial charging and a vehicle battery system including the power conversion device.

[0007] Technical Solution

[0008] In order to solve the above technical problems, according to one embodiment of the present disclosure, a power conversion device includes: a power conversion unit, which is configured to convert AC power into DC power to charge a battery when connected to an AC power supply; and an initial charging unit, which is connected to the secondary output side of the power conversion unit to initially charge the load side capacitor, and the output terminal of the power conversion unit is connected to the battery and the load side capacitor.

[0009] The power conversion unit may include: a first output terminal connected to a (+) terminal of a battery; a second output terminal connected to a (-) terminal of the battery; and a third output terminal connected to a load-side capacitor. The first output terminal and the third output terminal may be connected via a first switch, the AC power source may be a three-phase four-wire AC power source, the power conversion unit may include three power conversion units respectively connected to the three phases to perform power conversion, and the initial charging unit may be connected to a first output terminal of a first power conversion unit as one of the three power conversion units.

[0010] When the first switch is turned off, the first output terminal and the third output terminal may be connected inside the power conversion unit to initially charge the load-side capacitor.

[0011] The power conversion unit may include: a primary side, into which alternating current is input; a transformer, which is configured to convert the power of the primary side; and a secondary side, which is connected to the output of the transformer. The secondary side of the power conversion unit may include: a full-bridge circuit, which is connected to the output terminal of the transformer; a first high-side switch and a first low-side switch, which are connected in parallel with the full-bridge circuit; and an LC circuit, which is connected to the node connected to the first high-side switch and the first low-side switch. The first output terminal may be connected to the (+) terminal of the full-bridge circuit, the second output terminal may be connected to the (-) terminal of the full-bridge circuit, and the third output terminal may be connected to the node connecting the first inductor and the first capacitor of the LC circuit.

[0012] The initial charging unit may include: a second switch connected in series with the first capacitor; and a first diode connected in parallel with the first capacitor.

[0013] The third switch and the fourth switch having different connection directions may be connected in series to the respective first output terminals of the three power conversion units.

[0014] The power conversion device may further include a first capacitor unit connected in parallel to a node to which the first output terminals of the three power conversion units are connected.

[0015] The first capacitor unit, the fourth switch, the first diode, the first inductor, the first high-side switch, and the second low-side switch may form an H-bridge circuit.

[0016] When the load side capacitor is initially charged, the first switch may be turned off, the fourth switch connected to the first output terminal in the input direction may be turned on, the second switch may be turned off, and the first high side switch may be turned on. The voltage of the battery may be input through the first output terminal and output to the second output terminal to initially charge the load side capacitor.

[0017] When the DC power source is connected to the battery, the battery may be charged by the DC power source, and after the battery is charged, the load side capacitor may be initially charged.

[0018] If the voltage of the battery 220 is lower than the initial charging voltage of the load side capacitor, the second switch is turned off, the third switch and the fourth switch of the first power conversion unit are turned on, the third switch and the fourth switch of the second power conversion unit are turned off, the third switch and the fourth switch of the third power conversion unit are turned off, and the first high side switch of each of the first power conversion unit, the second power conversion unit, and the third power conversion unit is turned on, so that the load side capacitor is charged to the first voltage which is the battery voltage, and the first capacitor of the second power conversion unit and the first capacitor of the third power conversion unit can be charged to the first voltage. Thereafter, when the second switch is turned on, the third switch and the fourth switch of the first power conversion unit are turned off, the third switch and the fourth switch of the second power conversion unit are turned on, the third switch and the fourth switch of the third power conversion unit are turned on, and the first high side switch of each of the first power conversion unit, the second power conversion unit, and the third power conversion unit is turned on, the load side capacitor can be charged to the second voltage which is the sum of the first voltage and the battery voltage, and the first capacitor C1 can be charged to the first voltage. Subsequently, when the second switch is disconnected, the third switch and the fourth switch of the first power conversion unit are turned on, the third switch and the fourth switch of the second power conversion unit are turned on, the third switch and the fourth switch of the third power conversion unit are turned on, and the first high-side switch of each of the first power conversion unit, the second power conversion unit and the third power conversion unit is turned on, and the load side capacitor can be charged to the second voltage.

[0019] A vehicle battery system according to an embodiment of the present disclosure may include one of the power conversion devices.

[0020] Beneficial Effects

[0021] According to an embodiment of the present disclosure, by adding simple components to an on-board charger (OBC), initial charging can be performed without a separate relay and resistor for initial charging. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 is a block diagram of a power conversion device according to an embodiment of the present disclosure.

[0023] Figure 2 is a block diagram of a power conversion device according to an embodiment of the present disclosure.

[0024] Figure 3 An environment of a vehicle battery system to which the power conversion device according to an embodiment of the present disclosure is applied is shown.

[0025] Figures 4 to 6 is a circuit diagram of a power conversion device according to an embodiment of the present disclosure.

[0026] Figures 7 to 182 is a diagram for describing a power conversion device according to an embodiment of the present disclosure. DETAILED DESCRIPTION

[0027] Hereinafter, preferred embodiments of the present disclosure will be described in detail with reference to the accompanying drawings.

[0028] However, the technical concept of the present disclosure is not limited to some of the embodiments to be described below, but can be implemented in various other forms, and within the scope of the technical concept of the present disclosure, one or more components of the embodiments can be selectively combined and used interchangeably.

[0029] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as those commonly understood by those skilled in the art to which the present disclosure belongs. It will be further understood that, for example, terms defined in commonly used dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the relevant technology.

[0030] The terms used in the embodiments of the present disclosure are only used for the purpose of describing specific embodiments and are not intended to limit the inventive concept.

[0031] In the specification, unless the context clearly indicates otherwise, the singular may also include the plural, and “at least one (or more than one) of A, B, and C” used herein may include more than one combination of all possible combinations of A, B, and C.

[0032] When describing components according to embodiments of the present disclosure, terms such as "first", "second", (a), (b), etc. may be used. These terms are intended only to distinguish one component from another, and the terms do not limit the nature, order, or sequence of the constituent components. Such terms are intended only to distinguish one component from another, and the nature, order, sequence, etc. of the corresponding components are not limited by the terms.

[0033] In addition, when it is described that one component is “connected,” “coupled” or “engaged” to another component, it may be interpreted not only as being directly connected, coupled or engaged to another component but also as being “connected,” “coupled” or “engaged” through another component between the one component and the other component.

[0034] In addition, it should be understood that when each component is referred to as being formed or disposed “on (above)” or “under (below)” another component, it may be directly located “on” or “under” another component or one or more intermediate components may be indirectly formed therebetween. In addition, it will also be understood that when each component is referred to as being formed or disposed “on (above)” or “under (below)” another component, it may indicate both the upward and downward directions of the component.

[0035] Modified embodiments according to the present disclosure may include some parts of the various embodiments and some parts of other embodiments together. That is, the modified embodiment may include one embodiment in the various embodiments, but some parts may be omitted, and some parts may be included in other corresponding embodiments. Or, it may be the other way around. The features, structures, effects, etc. described in the embodiments are included in at least one embodiment, and are not necessarily limited to one embodiment. In addition, the features, structures, and effects shown in the various embodiments may be combined or modified by a technician in the field to which the embodiments belong relative to other embodiments. Therefore, the contents related to these combinations and modifications should be interpreted as being included in the scope of the embodiments.

[0036] Figure 1 is a block diagram of a power conversion device according to an embodiment of the present disclosure. Figure 2 is a block diagram of a power conversion device according to an embodiment of the present disclosure, Figure 3 An environment of a vehicle battery system to which a power conversion device is applied according to an embodiment of the present disclosure is shown, Figures 4 to 6 is a circuit diagram of a power conversion device according to an embodiment of the present disclosure, and Figures 7 to 18 2 is a diagram for describing a power conversion device according to an embodiment of the present disclosure.

[0037] The power conversion device 100 according to an embodiment of the present disclosure may be composed of a power conversion unit 110 and an initial charging unit 120 , and may include a controller 130 .

[0038] The power conversion device 100 according to the embodiment of the present disclosure may be a power conversion device 100 applied to a vehicle battery system, or may be an on-board charger (OBC) that charges a battery using power from an AC power source when connected to the AC power source.

[0039] When connected to the AC power source 210, the power conversion unit 110 converts AC power into DC power to charge the battery. The power conversion unit 110 converts AC power from the AC power source 210 into DC power to charge the battery. The power conversion unit 110 may include an input terminal connected to the AC power source 210 and an output terminal at which the converted power is output. The output terminal of the power conversion unit 110 may be connected to the battery 220 and may be connected to the load side capacitor 230. The battery 220 may be a vehicle battery, and the load side capacitor 230 may be a capacitor located at a load terminal connected to an internal load of the vehicle. The load side capacitor 230 may play a role in ensuring that the battery 220 and the load are stably connected.

[0040] The initial charging unit 120 may be connected to the secondary output side of the power conversion unit 110 to initially charge the load side capacitor 230. The initial charging unit 120 may be connected to the secondary output side of the power conversion unit 110 to form an initial charging circuit, and may initially charge the load side capacitor 230 according to the connection state of the power conversion unit 110 and the initial charging unit 120.

[0041] The power conversion device 100 according to the embodiment of the present disclosure can be connected to a vehicle battery system, such as Figure 3 The battery can be made up of a single cell or Figure 3 As shown, it can be composed of multiple batteries, and the battery voltage can be realized in various ways according to the connection state. Figure 3 As shown, for two 400V batteries, if BC1 is in the on state and BC2 and BC3 are in the off state, the two batteries can be connected in series to form an 800V battery. In addition, if BC1 is in the off state and BC2 and BC3 are in the on state, the two batteries can be connected in parallel to form a 400V battery, and if BC1 is in the off state, and one of BC2 and BC3 is in the on state and the other is in the off state, a single 400V battery can be formed.

[0042] When charging the battery, a DC charger (DC CHARGING STATION) can be connected, and when the DC charger is connected, FC1 and FC2 can be turned on. In addition to the DC charger, if the power conversion device 100 according to an embodiment of the present disclosure is connected to an AC power source such as a grid (GRID), AC (alternating current) can be converted into DC (direct current) to charge the battery. The power stored in the battery 220 can be output to the load through the load side capacitor C_L. The load side capacitor 230 can be connected to the high-voltage bus HV BUS. The power conversion device 100 may include three output terminals. Two output terminals can be connected to HV (+) and HV (-) of the high-voltage bus, respectively, and one output terminal (NON-NATIVE) can be connected to the battery.

[0043] The power conversion unit 110 may include a plurality of output terminals. The power conversion unit 110 may include a first output terminal 111 connected to the (+) terminal of the battery 220, a second output terminal 112 connected to the (-) terminal of the battery 220, and a third output terminal 113 connected to the load side capacitor 230. The first output terminal 111 and the third output terminal 113 may be connected to the switch MC1, and the second output terminal may be connected to the (-) terminal of the battery and the switch MC2. The switches MC1 and MC2 may be relays or metal oxide semiconductor field effect transistors (MOSFETs) and may include body diodes.

[0044] The input terminal of the power conversion unit 110 may be connected to the AC power source 210. Here, the AC power source 210 may be a three-phase four-wire AC power source, or may be a single-phase AC power source. When the AC power source 210 is a three-phase four-wire AC power source, the power conversion unit 110 may include three power conversion units connected to the three phases to convert power, respectively. The initial charging unit 120 may be connected to the first output terminal of the first power conversion unit, which is one of the three power conversion units.

[0045] Each power conversion unit may include a primary side to which the AC power of the AC power source 210 is input, a transformer 410 that converts the power of the primary side, and a secondary side connected to the output of the transformer 410. That is, the AC power source 210 may be connected to the primary side (PRIMARY) of the transformer 410, and the output terminal may be connected to the secondary side (SECONDARY) of the transformer 410. The input terminal connected to the AC power source 210 may be as shown in FIG. Figure 6 An EMI filter is shown included, and may include a primary side switch unit, a transformer, and a secondary side switch unit to convert the respective phases of the AC power source 210 .

[0046] The secondary side of the power conversion unit may include a full bridge circuit 420, a first high side switch and a first low side switch 430, and an LC circuit 440. The full bridge circuit 420 may be connected to the output terminal of the transformer 410, the first high side switch S1 and the first low side switch S2 may be connected to the full bridge circuit 420 in parallel, and the LC circuit 440 may be connected to a node to which the first high side switch S1 and the first low side switch S2 are connected.

[0047] The full-bridge circuit 420 may include two high-side switches and two low-side switches, and the high-side switch and the low-side switch are connected in series with each other, and the two nodes connecting the high-side switch and the low-side switch may be connected to the two terminals of the secondary side of the transformer in the power conversion unit, respectively. The high-side switch and the low-side switch connected in series may be complementary to each other and conduct electricity. The first high-side switch S1 and the first low-side switch S2 may be connected to the output terminal side of the full-bridge circuit 420, and the inductor L1 and the capacitor C1 may be connected to the node to which the first high-side switch S1 and the first low-side switch S2 are connected. Here, each switch may be a MOSFET, and may include a body diode.

[0048] In this case, the first output terminal 111 can be connected to the (+) terminal of the full bridge circuit 420, the second output terminal 112 can be connected to the (-) terminal of the full bridge circuit 420, and the third output terminal 113 can be connected to the node connecting the first inductor L1 and the first capacitor C1 of the LC circuit 440.

[0049] The initial charging unit 120 may include a switch S3 connected in series with the first capacitor C1 and a first diode D1 connected in parallel with the first capacitor C1. Switches S4 and S5 having different connection directions may be connected in series with the respective first output terminals of the three power conversion units. Each switch may be a MOSFET and may include a body diode. Depending on the type of MOSFET, switches S4 and S5 having different connection directions may be connected to each other at their sources, or may be connected to each other at their drains. The body diode may also be connected in the opposite direction.

[0050] The power conversion unit 110 may include a capacitor unit connected in parallel to a node to which the first output terminal 111 is connected. Here, the capacitor unit may include a plurality of capacitors connected in series, and may include two capacitors C2 and C3.

[0051] The capacitor unit, the switch S5, the first diode D1, the first inductor L1, the first high-side switch S1 and the second low-side switch S2 may form an H-bridge circuit 500. Figure 5 As shown, the battery 220 and the load side capacitor 230 can be connected through the H-bridge circuit 500, and the H-bridge circuit 500 can operate as a buck-boost converter. That is, the voltage of the battery 220 can be increased or decreased so that the load side capacitor 230 is initially charged according to the voltage level of the battery 220. Thus, the load side capacitor 230 can be initially charged using the voltage of the battery 220.

[0052] When performing initial charging with a boost circuit, a surge current may occur on the output side at the moment of applying a duty cycle. Since a surge current may occur at the beginning of initial charging, the battery 220 and the load side capacitor 230 may be required to work as an H-bridge to prevent the surge current from occurring until the output side capacitor C1 is fully charged. The capacitor unit, the switch S5, the first diode D1, the first inductor L1, the first high side switch S1 and the second low side switch S2 can form an H-bridge circuit 500 to solve the surge current.

[0053] By adding only the switch S3, the diode D1, the switches S4 and S5, and the capacitors C2 and C3 to the configuration of the power conversion unit 110 that converts the AC power of the AC power source 210 into DC power on the first output terminal side, the load side capacitor 230 can be initially charged.

[0054] In a state where the switch MC1 is turned off, the first output terminal 111 and the third output terminal 113 may be connected inside the power conversion unit 110 to initially charge the load side capacitor 230 .

[0055] When the load side capacitor 230 is initially charged, the switch MC1 is turned off, the switch S5 connected to the first output terminal 111 in the output direction is turned on, the switch S3 is turned off, and the first high side switch S1 is turned on. In this case, the voltage of the battery 220 is input through the first output terminal 111 and output to the second output terminal 112 to initially charge the load side capacitor 230.

[0056] In order to prevent damage that may occur due to a voltage difference when the voltage of the battery 220 is directly connected to the load side capacitor 230, it is necessary to initially charge the load side capacitor 230 with a required voltage. To this end, by connecting the battery 220 and the load side capacitor 230 via the initial charging unit 120 and the power conversion unit 110, the load side capacitor 230 can be initially charged by the voltage of the battery 220 before the battery 220 is directly connected to the load side capacitor 230. To achieve this goal, it is necessary to connect the (+) terminal of the battery 220 to the first output terminal 111 instead of directly connecting the (+) terminal of the battery 220 to the load side capacitor 230. Therefore, MC1 is disconnected and MC2 is connected, S5 of switches S4 and S5 is turned on and S4 is disconnected, S2 and S3 are disconnected and S1 is connected, so that a connection is made between the battery 220 and the load side capacitor 230 via a path passing through the body diode of the first output terminal 111, S5 and S4, the first inductor L1, S1 and the third output terminal 113 to initially charge the load side capacitor 230.

[0057] In this case, as described above, the capacitor unit, the switch S5, the first diode D1, the first inductor L1, the first high-side switch S1, and the second low-side switch S2 may form an H-bridge circuit 500 that steps up or steps down the voltage of the battery 220 to initially charge the load-side capacitor 230. By forming a simple circuit with the elements within the power conversion unit 110, the load-side capacitor 230 may be initialized without a separate relay and resistor for initial charging.

[0058] When the load side capacitor 230 is initialized using the battery 220, the control unit 130 may control the switch according to the situation to perform the initial charging of the load side capacitor 230. For example, the order of operations may be different for various situations, such as when the battery 220 is charged with a DC charger, when the battery 220 is charged while the vehicle is running, when the battery 220 is charged with an AC power source 210, when the battery 220 voltage is low, etc.

[0059] When the DC power source is connected to the battery 220 , the battery 220 may be charged via the DC power source, and after the battery 220 is charged, the load side capacitor 230 may be initially charged.

[0060] When the DC charger is connected and the battery 220 is charged, the power from the battery 220 can be used to initially charge the load-side capacitor via the power conversion device 100 (ie, the OBC). Figures 7 to 9 As shown, after the DC charger charges the battery 220 to 800V and the load side capacitor 230 is initially charged to 800V, the battery 220 and the load side capacitor 230 can be connected. To this end, first, when the plug of the 800V DC charger is connected to the vehicle (S101), the DC charging voltage is detected (S102) and it is determined whether the DC charging voltage is the same as the battery voltage of 800V (S103). If the battery voltage and the DC charging voltage are not the same as each other, FC1 and FC2 can be kept disconnected (S104) to prevent the DC charger and the battery 220 from being connected to maintain safety. If the battery voltage and the DC charging voltage are the same as each other, the battery forms a battery pack of 800V, and FC1 and FC2 are turned on to charge the battery (S105). When the battery is charged, MC2 is turned on (S106), and the high voltage bus HV BUS is tested with OBC (S107). If the test on the high-voltage bus fails, an HV BUS error is sent to an external MCU, etc., and the test circuit is disconnected (S108). If the test on the high-voltage bus passes, the high-voltage bus capacitor, which is a load-side capacitor, is initially charged (S109). Initial charging is performed after determining that the initial charging voltage of the high-voltage bus capacitor reaches the target voltage (S110), and when the initial charging is completed, MC1 is turned on (S111), and the initial charging of the OBC is disconnected (S112) to directly connect the battery 220 and the high-voltage bus, thereby supplying the battery voltage to the load (S113). Fig. 9 As shown, MC1 is disconnected and MC2 is turned on to connect the battery 220 and the load-side capacitor 230 through a path formed inside the OBC to test the high-voltage bus and initialize the load-side capacitor, and then MC1 can be turned on to directly connect the battery 220 to the high-voltage bus to supply the battery voltage to the load.

[0061] The load side capacitor can be initially charged with power from the battery 220 through the OBC, i.e., the power conversion device 100, in the current state of the battery 220 without any connection to the battery 220 for charging, for example, when the vehicle is running. Figures 10 to 12As shown, after the load side capacitor 230 is initially charged to 800V, which is the voltage of the battery 220, the battery 220 and the load side capacitor 230 can be connected. To this end, when the vehicle start is detected (S102), MC2 is turned on (S202), and the high-voltage bus HV BUS is tested with OBC (S203). If the test of the high-voltage bus fails, the HVBUS error is sent to an external MCU, etc., and the test circuit is disconnected (S204). If the test of the high-voltage bus passes, the high-voltage bus capacitor as the load side capacitor is initially charged (S205). After determining that the initial charging voltage of the high-voltage bus capacitor reaches the target voltage, the initial charging is performed (S206), and when the initial charging is completed, MC1 is turned on (S207), and the initial charging of the OBC is disconnected (S208) to directly connect the battery 220 and the high-voltage bus to supply the battery voltage to the load (S209). As Fig.12 As shown, MC1 is disconnected and MC2 is turned on to connect the battery 220 and the load-side capacitor 230 through a path formed inside the OBC to test the high-voltage bus and initialize the load-side capacitor, and then MC1 can be turned on to directly connect the battery 220 to the high-voltage bus to supply the battery voltage to the load.

[0062] When the AC power source is connected to the OBC and the battery 220 is charged by the OBC, the power from the battery 220 can be used to initially charge the load-side capacitor by the OBC as the power conversion device 100. For example, Figures 13 to 15 As shown, when the AC power supply 210 is connected, the load side capacitor 230 is initially charged to 800V, and then the battery 220 and the load side capacitor 230 are connected, and the battery 220 can be charged to 800V. To this end, first, when the plug of the AC power supply is connected to the vehicle (S301), MC2 is turned on (S302), and the high-voltage bus HV BUS is tested with OBC (S303). If the test of the high-voltage bus fails, the HV BUS error is sent to an external MCU, etc., and the test circuit is disconnected (S304). If the test of the high-voltage bus passes, the high-voltage bus capacitor as the load side capacitor is initially charged (S305). After determining that the initial charging voltage of the high-voltage bus capacitor reaches the target voltage, the initial charging is performed (S306), and when the initial charging is completed, the MC1 is turned on (S307), and the initial charging of the OBC is turned off (S308), so as to directly connect the battery 220 and the high-voltage bus to supply the battery voltage to the load (S311), the clamping capacitor in the primary side of the OBC is initially charged (S309), and the OBC is turned on (S310) to charge the battery. Fig. 9As shown, after the high voltage bus is tested with an AC power source connected to the OBC and the load side capacitor 230 is initially charged, MC1 can be turned on to directly connect the battery 220 to the high voltage bus to supply the battery voltage to the load.

[0063] If the voltage of the battery 220 is lower than the initial charging voltage of the load side capacitor 230, the voltage of the battery 220 needs to be increased to initially charge the load side capacitor 230. To this end, first, when the switch S3 is turned off, the switch S4 and the switch S5 of the first power conversion unit BLOCK C are turned on, and the switches S4 and the switches S5 of the second power conversion unit BLOCK A and the third power conversion unit BLOCK B are turned off, and the high side switch S1 of the first power conversion unit, the second power conversion unit, and the third power conversion unit is turned on, and the load side capacitor 230 can be charged to the first voltage as the battery voltage, and the first capacitor C1 of the second power conversion unit BLOCK A and the third power conversion unit BLOCK B can be charged to the first voltage.

[0064] Thereafter, when the switch S3 is turned on, the switch S4 and the switch S5 of the first power conversion unit BLOCK C are turned off, and the switch S4 and the switch S5 of the second power conversion unit BLOCK A and the third power conversion unit BLOCK B are turned on, and the high-side switch S1 of the first power conversion unit, the second power conversion unit, and the third power conversion unit is turned on, the load side capacitor can be charged to a second voltage which is the sum of the first voltage and the battery voltage, and the first capacitor C1 can be charged to the first voltage.

[0065] Afterwards, when the switch S3 is turned on, the switch S4 and the switch S5 of the first power conversion unit BLOCK C are turned on, and the switch S4 and the switch S5 of the second power conversion unit BLOCK A and the third power conversion unit BLOCK B are turned off, and the high-side switch S1 of the first power conversion unit, the second power conversion unit and the third power conversion unit is turned on, and the load side capacitor can be charged to the second voltage.

[0066] If the voltage of the battery 220 is lower than the initial charging voltage of the load side capacitor 230, for example, Figures 16 to 18 As shown in FIG. 1 , if it is necessary to charge the battery to 400 V using a 400 V charger as a DC charger and initially charge the load side capacitor to 800 V, the initial charging can be performed as follows. In this case, since the voltage of the battery and the voltage of the load side capacitor are different, the battery and the load side capacitor can be connected through the OBC instead of directly connecting them to supply power to the load.

[0067] To this end, first, when the plug of the DC charger is connected to the vehicle (S401), the DC charging voltage is detected (S402) and it is determined whether the DC charging voltage is 400V (S403). If the DC charging voltage is not 400V, FC1 and FC2 remain disconnected (S404) to prevent the DC charger and the battery (220) from being connected, thereby maintaining safety. If the DC charging voltage is 400V, the battery forms a 400V battery pack, and FC1 and FC2 are turned on to charge the battery (S405). When the battery is charged, MC2 is turned on (S406), and the high-voltage bus HV BUS is tested with OBC (S407). If the test of the high-voltage bus fails, the HVBUS error is sent to an external MCU, etc., and the test circuit is disconnected (S408). If the test of the high-voltage bus passes, the high-voltage bus capacitor as a load-side capacitor is initially charged (S409). After determining that the initial charging voltage of the high-voltage bus capacitor reaches the target voltage, initial charging is performed (S410), and when the initial charging is completed, MC1 is turned on (S411), and the initial charging of the OBC is disconnected (S412) to directly connect the battery 220 and the high-voltage bus to supply the battery voltage to the load (S413).

[0068] like Fig.18 As shown, if the voltage of the battery 220 is lower than the initial charging voltage of the load side capacitor 230, first, MC1 is turned off and MC2 is turned on to initially charge the load side capacitor and the output side capacitor of the second power conversion unit BLOCK A and the third power conversion unit BLOCK B to the first voltage as the battery voltage through the path formed by the first power conversion unit BLOCK C in the OBC. In this case, BLOCK C can operate as an H-bridge circuit. The B2B switches A and B of the second power conversion unit BLOCK A and the third power conversion unit BLOCK B are turned off, the high-side switch (HIGH-SIDE MOSFETS) is turned on, and the auxiliary MOSFET as the switch S3 of the first power conversion unit BLOCK C is turned off to initially charge the load side capacitor to the first voltage of 400V.

[0069] After that, the B2B switches A and B of the second power conversion unit BLOCK A and the third power conversion unit BLOCK B are turned on, and the B2B switch C of the first power conversion unit BLOCK C is turned off, so that the load side capacitor is charged through the path formed by the second power conversion unit BLOCK A and the third power conversion unit BLOCK B, and the first voltage of 400V as the battery voltage is added to the first voltage 400V that has been initially charged to the output side capacitor of the second power conversion unit BLOCK A and the third power conversion unit BLOCK B in the previous stage to initially charge the load side capacitor to the second voltage 800V. In this case, BLOCK A and BLOCK B can operate as a boost circuit. In this case, the auxiliary MOSFET as the switch S3 of the first power conversion unit BLOCK C is turned on to initially charge the output side capacitor of the first power conversion unit BLOCK C to the first voltage of 400V. In this case, the first power conversion unit BLOCK C can operate as a buck circuit.

[0070] After that, the B2B switch C of the first power conversion unit BLOCK C is turned on to charge the load side capacitor through a path formed by the first power conversion unit BLOCK C, the second power conversion unit BLOCK A, and the third power conversion unit BLOCK B. In this case, the first power conversion unit BLOCK C can also operate as a boost circuit similar to BLOCK A and BLOCK B. Thus, the battery voltage of 400V can be increased to 800V to supply a voltage of 800V to the load side capacitor 230. In this case, MC1 can be kept disconnected so that the battery 220 is not directly connected to the load side capacitor 230.

[0071] The vehicle battery system according to the embodiment of the present disclosure may include an OBC as the power conversion device according to the embodiment of the present disclosure. Figures 1 to 18 The vehicle battery system includes a battery, and a power conversion device that converts power from the battery and outputs it to a load, or is connected to an AC power source to convert power from the AC power source into power for charging the battery and outputs the power to the battery.

[0072] In order to solve the above technical problems, the power conversion device according to the embodiment of the present disclosure includes: a power conversion unit, when connected to an AC power source to charge a battery, converts AC power into DC power; and an initial charging unit, connected to the secondary output side of the power conversion unit and initially charging the load side capacitor, and the output terminal of the power conversion unit is connected to the battery and the load side capacitor. In addition, the power conversion unit includes a first output terminal connected to the (+) terminal of the battery, a second output terminal connected to the (-) terminal of the battery, and a third output terminal connected to the load side capacitor. The first output terminal and the third output terminal are connected by a first switch, and the AC power source is a three-phase four-wire AC power source. The power conversion unit includes three power conversion units respectively connected to the three phases to perform power conversion, and the initial charging unit is connected to the first output terminal of the first power conversion unit as one of the three power conversion units. When the first switch is disconnected, the first output terminal and the third output terminal can be connected inside the power conversion unit to initially charge the load side capacitor.

[0073] It will be appreciated by those skilled in the art in relation to the present embodiment that the present embodiment may be implemented in a modified form without departing from the basic features described above. Therefore, the disclosed method should be considered from an explanatory perspective rather than a restrictive perspective. The scope of the present disclosure is presented in the claims, rather than in the above description, and all differences within the scope equivalent thereto should be interpreted as included in the present disclosure.

Claims

1. A power conversion device, comprising: a power conversion unit, the power conversion unit being configured to convert AC power into DC power to charge the battery when connected to an AC power source; as well as an initial charging unit connected to the secondary output side of the power conversion unit and configured to initially charge the load-side capacitor, The output terminal of the power conversion unit is connected to the battery and the load-side capacitor.

2. The power conversion device according to claim 1, wherein: The power conversion unit comprises: a first output terminal connected to a (+) terminal of the battery; a second output terminal connected to a (-) terminal of the battery; and a third output terminal connected to the load-side capacitor, wherein the first output terminal and the third output terminal are connected via a first switch, Wherein, the AC power supply is a three-phase four-wire AC power supply, The power conversion unit includes three power conversion units respectively connected to the three phases to convert power, and The initial charging unit is connected to the first output terminal of a first power conversion unit, and the first power conversion unit is one of the three power conversion units.

3. The power conversion device according to claim 2, wherein: When the first switch is turned off, the first output terminal and the third output terminal are connected inside the power conversion unit to initially charge the load side capacitor.

4. The power conversion device according to claim 2, wherein: The power conversion unit comprises: a primary side into which the alternating current is input; a transformer configured to convert the primary-side power; and a secondary side, the secondary side being connected to the output of the transformer, Wherein, the secondary side of the power conversion unit includes: a full-bridge circuit connected to an output terminal of the transformer; a first high-side switch and a first low-side switch, the first high-side switch and the first low-side switch being connected in parallel with the full-bridge circuit; and an LC circuit connected to a node to which the first high-side switch and the first low-side switch are connected, wherein the first output terminal is connected to the (+) terminal of the full-bridge circuit, wherein the second output terminal is connected to the (-) terminal of the full-bridge circuit, and The third output terminal is connected to a node connecting the first inductor and the first capacitor of the LC circuit.

5. The power conversion device according to claim 4, wherein: The initial charging unit comprises: a second switch connected in series with the first capacitor; and A first diode is connected in parallel with the first capacitor.

6. The power conversion device according to claim 5, wherein: A third switch and a fourth switch having different connection directions are connected in series to the respective first output terminals of the three power conversion units.

7. The power conversion device according to claim 6, comprising: A first capacitor unit is connected in parallel to a node to which the first output terminals of the three power conversion units are connected.

8. The power conversion device according to claim 7, wherein: The first capacitor unit, the fourth switch, the first diode, the first inductor, the first high-side switch, and the second low-side switch form an H-bridge circuit.

9. The power conversion device according to claim 7, wherein: When the load side capacitor is initially charged, the first switch is turned off, the fourth switch connected to the first output terminal in the input direction is turned on, the second switch is turned off, and the first high side switch is turned on, and The voltage of the battery is input through the first output terminal and output to the second output terminal to initially charge the load-side capacitor.

10. The power conversion device according to claim 9, wherein: When a DC power source is connected to the battery, the battery is charged by the DC power source, and Wherein, after the battery is charged, the load-side capacitor is initially charged.

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