Charging device

Abstract

To provide a charger which can perform a charging operation with high charging efficiency.SOLUTION: A charger 1 includes: a PFC circuit 20 containing inductors 25 to 27 connected to input terminals IN1 to IN3, respectively, and three switch legs 21 to 23 connected to the respective inductors; and a relay network 2 including a plurality of relays. When the input terminals IN1-IN3 are linked to respective phases of a three-phase power supply, the relay network 2 connects to each phase of the three-phase power supply to the corresponding one of the respective switch legs, and the PFC circuit 20 operates as a three-phase boost PFC. When a single-phase power source is connected to one of the input terminals IN1 to IN3, the relay network 2 connects the single-phase power source to the switch legs 21 and 22, and connects the switch leg 23 to a neutral point, and the PFC circuit 20 operates as a single-inductor type interleaved single-phase full-bridge PFC.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a charging device. [Background technology]

[0002] Charging the high-voltage battery is essential for electric vehicles to operate. The charger installed inside the vehicle can convert the power input from a commercial AC power source into the voltage required by the battery. This is called an OBC (On Board Charger).

[0003] An OBC includes a PFC (Power Factor Correction) circuit that corrects the power factor (PF) and a DC-DC converter that converts the voltage required by the battery. A wide range of AC commercial AC power is input to the PFC circuit. The OBC's DC-DC converter is realized by a boost converter without a transformer. However, due to the characteristics of the boost converter, charging is only possible when the output voltage is higher than the input voltage.

[0004] Additionally, an OBC can be implemented by combining a PFC implemented in a buck converter with a boost converter. This OBC can convert a wide range of input voltages and provide a wide range of output voltages, but it has limitations such as high output current ripple being applied to the battery because the boost converter is directly connected to the battery, different operating points due to differences between the motor output and the OBC output, and low charging efficiency. Summary of the Invention [Problem to be solved by the invention]

[0005] To provide a charging device capable of performing charging operation with high charging efficiency in accordance with a wide range of input power sources and a wide range of battery charging voltages. [Means for solving the problem]

[0006] A charging device according to the present invention includes a power factor correction (PFC) circuit including first to third inductors connected to first to third input terminals, respectively, and first to third switch legs connected to the first to third inductors, and a relay network including a plurality of relays. When the first to third input terminals are connected to each phase of a three-phase power supply, the relay network connects each phase of the three-phase power supply to a corresponding one of the first to third switch legs, and the PFC circuit operates as a three-phase boost PFC. When a single-phase power supply is connected to any one of the first to third input terminals, the relay network connects the single-phase power supply to the first and second switch legs and connects the third switch leg to a neutral point, and the PFC circuit operates as an interleaved single-phase full-bridge PFC of a single inductor type.

[0007] The relay network may include a first relay having one end connected to the first input terminal and the first inductor and the other end connected to the second input terminal and the second inductor, a second relay connected between the second input terminal and the second inductor, a third relay connected between the third input terminal and the third inductor, a fourth relay connected between a neutral point and the third inductor, and a fifth relay connected in parallel to the third inductor.

[0008] When the first to third input terminals are connected to the respective phases of a three-phase power supply, the charging device turns off the first relay, the fourth relay, and the fifth relay, and turns on the second relay and the third relay.

[0009] When a single-phase power supply is connected to the first input terminal, the charging device turns on the first relay, the fourth relay, and the fifth relay, and turns off the second relay and the third relay.

[0010] The charging device may further include a power conversion circuit coupled between the PFC circuit and a battery to transfer power from the battery to the PFC circuit.

[0011] The first switch leg includes a first switch coupled between the first inductor and a first input terminal of the power conversion circuit and a second switch coupled between the first inductor and a second input terminal of the power conversion circuit, the second switch leg includes a third switch coupled between the second inductor and the first input terminal of the power conversion circuit and a fourth switch coupled between the second inductor and the second input terminal of the power conversion circuit, and the third switch leg includes a fifth switch coupled between the third inductor and the first input terminal of the power conversion circuit and a sixth switch coupled between the third inductor and the second input terminal of the power conversion circuit.

[0012] When a single-phase power supply is connected to the first input terminal, the charging device can turn on the first relay, the fourth relay, and the fifth relay and turn off the second relay and the third relay. During a period when the single-phase power supply has a positive voltage, a period when the first switch, the third switch, and the sixth switch are in an on state and a period when the second switch, the fourth switch, and the sixth switch are in an on state are repeated. During a period when the single-phase power supply has a negative voltage, a period when the second switch, the fourth switch, and the fifth switch are in an on state and a period when the first switch, the third switch, and the fifth switch are in an on state are repeated.

[0013] The relay network may further include a sixth relay connected in parallel to a resistor connected between the first input terminal and the first inductor, and the charging device may turn on the sixth relay after a peak of a voltage input to the PFC circuit.

[0014] The charging device may further include a relay control circuit connected to the first to third input terminals, detecting an input terminal to which a power source is connected among the first to third input terminals, and controlling the relay network.

[0015] According to another aspect of the present invention, a charging device includes a PFC (Power Factor Correction) circuit including first to third inductors respectively connected to first to third input terminals and first to third switch legs respectively connected to the first to third inductors, and a relay network including a plurality of relays. When the first to third input terminals are connected to each phase of a three-phase load, the relay network connects each phase of the three-phase power supply to a corresponding one of the first to third switch legs, and the PFC circuit operates as a three-phase inverter. When a single-phase load is connected to any one of the first to third input terminals, the relay network connects the single-phase load to the first and second switch legs and connects the third switch leg to a neutral point, and the PFC circuit operates as a single-phase inverter.

[0016] The relay network may include a first relay having one end connected to the first input terminal and the first inductor and the other end connected to the second input terminal and the second inductor, a second relay connected between the second input terminal and the second inductor, a third relay connected between the third input terminal and the third inductor, a fourth relay connected between a neutral point and the third inductor, and a fifth relay connected in parallel to the third inductor.

[0017] When the first to third input terminals are connected to the respective phases of a three-phase load, the charging device can turn off the first relay, the fourth relay, and the fifth relay, and turn on the second relay and the third relay.

[0018] When a single-phase load is connected to the first input terminal, the charging device may turn on the first relay, the fourth relay, and the fifth relay, and turn off the second relay and the third relay.

[0019] The charging device may further include a relay control circuit connected to the first to third input terminals, detecting an input terminal to which a load is connected among the first to third input terminals, and controlling the relay network.

[0020] The charging device may further include a power conversion circuit coupled between the PFC circuit and a battery to transfer power from the battery to the PFC circuit.

[0021] The first switch leg includes a first switch coupled between the first inductor and a first input terminal of the power conversion circuit and a second switch coupled between the first inductor and a second input terminal of the power conversion circuit, the second switch leg includes a third switch coupled between the second inductor and the first input terminal of the power conversion circuit and a fourth switch coupled between the second inductor and the second input terminal of the power conversion circuit, and the third switch leg includes a fifth switch coupled between the third inductor and the first input terminal of the power conversion circuit and a sixth switch coupled between the third inductor and the second input terminal of the power conversion circuit.

[0022] When a single-phase load is connected to the first input terminal, the charging device may turn on the first relay, the fourth relay, and the fifth relay and turn off the second relay and the third relay. The first switch and the second switch may alternately switch, the third switch and the fourth switch may alternately switch, an on period of the first switch may entirely overlap with an on period of the fourth switch, an on period of the third switch may entirely overlap with an on period of the second switch, the fifth switch may be in an off state, and the sixth switch may be in an on state. [Effects of the Invention]

[0023] The present invention provides a charging device that is capable of performing charging operations with high charging efficiency in accordance with a wide range of input power sources and a wide range of battery charging voltages, and has a simpler circuit structure than conventional devices. [Brief explanation of the drawings]

[0024] [Figure 1] 1 is a diagram illustrating a charging device according to an embodiment. [Figure 2] FIG. 2 is a circuit diagram for explaining operation when the AC commercial power supply is three-phase. [Figure 3] FIG. 2 is a circuit diagram for explaining operation when the AC commercial power supply is single-phase. [Figure 4A] FIG. 2 is a circuit diagram for explaining the operation of a PFC circuit when an input power supply is single-phase according to an embodiment. [Figure 4B] FIG. 2 is a circuit diagram for explaining the operation of a PFC circuit when an input power supply is single-phase according to an embodiment. [Figure 4C] FIG. 2 is a circuit diagram for explaining the operation of a PFC circuit when an input power supply is single-phase according to an embodiment. [Figure 4D] FIG. 2 is a circuit diagram for explaining the operation of a PFC circuit when an input power supply is single-phase according to an embodiment. [Figure 5] 10A and 10B are diagrams for explaining the operation when the charging device according to the embodiment supplies power to a three-phase load in the reverse direction. [Figure 6] 10A and 10B are diagrams for explaining the operation when the charging device according to the embodiment supplies power to a single-phase load in the reverse direction. [Figure 7] FIG. 2 is a diagram illustrating a switching operation of a PFC circuit according to an embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0025] Hereinafter, the embodiments disclosed herein will be described in detail with reference to the accompanying drawings. Identical or similar components will be designated by the same or similar reference numerals, and redundant descriptions thereof will be omitted. The suffixes "module" and / or "section" for components used in the following description are given or used interchangeably solely for the convenience of writing the specification, and do not have any distinct meanings or functions. Furthermore, when describing the embodiments disclosed herein, if it is determined that a detailed description of such well-known technology may obscure the gist of the embodiments disclosed herein, such a detailed description will be omitted. Furthermore, the accompanying drawings are merely intended to facilitate understanding of the embodiments disclosed herein, and it should be understood that the accompanying drawings do not limit the technical ideas disclosed herein, and all modifications, equivalents, and alternatives within the spirit and technical scope of the present invention are included.

[0026] Terms including ordinal numbers such as first, second, etc. are used to describe various components, but the components are not limited by the terms. The terms are used only to distinguish one component from another.

[0027] When a component is referred to as being "coupled" or "connected" to another component, it should be understood that the component may be directly coupled or connected to the other component, but that there may be other components in between. Conversely, when a component is referred to as being "directly coupled" or "directly connected" to another component, it should be understood that there are no other components in between.

[0028] In this application, the use of terms such as "comprise" or "have" is intended to specify the presence of any feature, number, step, operation, component, part, or combination thereof described in the specification, but it should be understood that it does not preclude the possibility of the presence or addition of one or more other features, numbers, steps, operations, components, parts, or combinations thereof.

[0029] FIG. 1 is a diagram showing a charging device according to an embodiment.

[0030] The charging device 1 includes a relay network 2, a relay control circuit 3, a power control circuit 4, an AC input filter 10, a PFC circuit 20, and a power conversion circuit 30. The charging device 1 can convert AC commercial power to generate charging power for charging a battery 40. For example, a positive terminal (+) of the battery 40 is connected to the output terminal OUT1, and a negative terminal (-) of the battery 40 is connected to the output terminal OUT2.

[0031] The relay network 2 controls the on / off of a plurality of relays RL1-RL6 according to the phase of the AC commercial power supply, thereby controlling the connection relationship between the PFC circuit 20 and the AC commercial power supply.

[0032] The relay network 2 includes a plurality of relays RL1-RL6, and the relay control circuit 3 is connected to a plurality of input terminals IN1-IN3 connected to an AC commercial power supply, detects the phase of the AC commercial power supply, and controls the plurality of relays RL1-RL6 according to the detected phase. The relay control circuit 3 generates a plurality of relay control signals RLS1-RLS6 for controlling the on / off of the plurality of relays RL1-RL6 according to the detected phase, and supplies the generated signals to the plurality of relays RL1-RL6. The plurality of relays RL1-RL6 are turned on (closed) or off (open) by the plurality of relay control signals RLS1-RLS6.

[0033] For example, when the AC commercial power supply is three-phase, the relay control circuit 3 can generate relay control signals RLS2 and RLS3 that turn on the multiple relays RL2 and RL3 and relay control signals RLS1, RLS4, and RLS6 that turn off the multiple relays RL1, RL4, and RL6, and supply these signals to the multiple relays RL1-RL6. At this time, the relay control circuit 3 can also generate a phase detection signal SL that indicates the three phases and transmit it to the power control circuit 4.

[0034] Alternatively, when the AC commercial power supply is single-phase, the relay control circuit 3 can generate relay control signals RLS1, RLS4, RLS6 that turn on the multiple relays RL1, RL4, RL6 and relay control signals RLS2, RLS3 that turn off the multiple relays RL2, RL3, and supply these signals to the multiple relays RL1-RL6. In this case, the relay control circuit 3 can also generate a phase detection signal SL that indicates single phase and transmit it to the power control circuit 4.

[0035] The relay control circuit 3 can generate and supply to the relay RL5 a relay control signal RLS5 that turns on the relay RL5 when a predetermined period of time has elapsed since the start of the charging operation, regardless of whether the charging is single-phase or three-phase.

[0036] One end of relay RL1 is connected to one end of inductor 25 and input terminal IN1, and the other end of relay RL1 is connected between input terminal IN2 and one end of inductor 26. Relay RL2 is connected to input terminal IN2 and one end of inductor 26, relay RL3 is connected to input terminal IN3 and one end of inductor 27, and relay RL4 is connected between neutral point N and one end of inductor 27. Relay RL5 is connected between input terminal IN1 and one end of inductor 25, and relay RL6 is connected in parallel with inductor 27. The multiple relays RL1-RL6 can be realized by electromagnetic relays or mechanical relays.

[0037] The AC input filter 10 removes electromagnetic interference (EMI) from AC commercial power supplied via multiple input terminals IN1-IN3. The AC input filter 10 includes multiple inductors provided in input lines between each input terminal and the PFC circuit 20, and multiple capacitors connected to the input lines, with the multiple capacitors connected to each input line in a Y-CAP structure. However, this is just one example of an AC input filter, and the invention is not limited thereto. AC input filters that can be realized with various known circuits can be applied.

[0038] Fuse F1 is coupled between input terminal IN1 and inductor 25, and fuse F2 is coupled between input terminal IN3 and inductor 27.

[0039] PFC circuit 20 includes three switch legs 21-23, three inductors 25-27, and a PFC link capacitor 24. PFC circuit 20 can be operated by a switch control signal supplied from power control circuit 4. Power control circuit 4 can control the switching operation of PFC circuit 20 according to whether the AC commercial power supply is single-phase or three-phase, using phase detection signal SL.

[0040] When the AC commercial power supply is three-phase, the PFC circuit 20 receives a three-phase line voltage and operates as a 3-leg boost PFC. When the AC commercial power supply is single-phase, the PFC circuit 20 receives a voltage between input terminal IN1 and neutral point N and operates as a PFC with a single-inductor interleaved single-phase full-bridge structure. That is, in the three-phase case, the PFC circuit 20 uses each of the three input terminals IN1, IN2, and IN3 as a power source, and in the single-phase case, it uses the voltage between input terminal IN1 and neutral point N as a power source. In the single-phase case, the relay RL1 is turned on and all three switch legs 21-23 are used for power transmission. Of these, switch leg 23 is connected to neutral point N, and the inductor 27 is deactivated by turning on the relay RL6. Then, the PFC circuit 20 is transformed into a single inductor structure between the input terminal IN1 and the neutral point N, and has an interleaved single-phase full-bridge structure. In this case, the PFC circuit 20 can operate under unipolar totem pole control.

[0041] The PFC link capacitor 24 includes two capacitors C1 and C2, and generates a DC voltage by charging the current transmitted by the operation of each of the three switch legs 21-23.

[0042] The power conversion circuit 30 converts the voltage charged in the PFC link capacitor 24 to generate and supply a DC voltage suitable for a load. Two input terminals DCN1 and DCN2 of the power conversion circuit 30 are connected to both ends of the PFC link capacitor 24. Although a load is not shown in Fig. 1, an example of a load is a battery, which is connected between the two output terminals OUT1 and OUT2 and can be charged.

[0043] The power conversion circuit 30 includes two DC-DC converters connected in parallel between two input terminals DCN1, DCN2 and two output terminals OUT1, OUT2. The structure in which two DC-DC converters are connected in parallel is an example according to one embodiment, and the invention is not limited thereto. The power conversion circuit 30 may be realized with an appropriate number of DC-DC converters depending on the size of the load.

[0044] The DC-DC converter 31 includes four switching elements T1-T4 connected in a full bridge configuration on one side, four switching elements T5-T8 connected in a full bridge configuration on the other side, an isolation transformer TR1 between the one side and the other side, and a capacitor C3.

[0045] The DC-DC converter 32 includes four switching elements P1-P4 connected in a full bridge configuration on one side, four switching elements P5-P8 connected in a full bridge configuration on the other side, an isolation transformer TR2 between the one side and the other side, and a capacitor C4.

[0046] Power control circuit 4 can control the power conversion operations of DC-DC converter 31 and DC-DC converter 32. For example, power control circuit 4 receives feedback of the output voltage supplied to battery 40, and can generate control signals for controlling the switching frequency or duty ratio of DC-DC converter 31 and DC-DC converter 32, and supply these to DC-DC converter 31 and DC-DC converter 32. The specific control method is the same as the control method for a converter with an LLC resonant full-bridge structure, so a detailed description will be omitted.

[0047] 1, the DC-DC converters 31 and 32 are implemented as LLC resonant full-bridges, but the invention is not limited to this and may be implemented as other types. The operation of the DC-DC converters is obvious to those skilled in the art of the present invention, so a detailed description will be omitted.

[0048] FIG. 2 is a circuit diagram for explaining the operation when the AC commercial power supply is three-phase.

[0049] As shown in FIG. 2, a three-phase power supply is transmitted to three input terminals IN1, IN2, and IN3 via three inductors L1, L2, and L3, respectively.

[0050] Relay control circuit 3 detects that the AC commercial power supply is three-phase, turns on relays RL2 and RL3, turns off relays RL1, RL4, and RL6, and turns on relay RL5 after the voltage input to PFC circuit 20 reaches its peak. Relay RL5 protects elements such as PFC link capacitor 24 when an inrush current flows due to a high voltage at the input terminal. Relay RL5 remains off until the voltage input to PFC circuit 20 reaches its peak, and the input from input terminal IN1 is supplied to PFC circuit 20 via resistor 11. After the peak is reached, relay RL5 is turned on, and the input from input terminal IN1 is supplied to PFC circuit 20 via relay RL5, not via resistor 11. Relay RL5 remains off until the voltage input to PFC circuit 20 reaches its peak, regardless of whether it is single-phase or three-phase, and turns on after the peak.

[0051] When the AC commercial power supply is three-phase, input terminals IN1, IN2, and IN3 are connected to inductors 25, 26, and 27, respectively, and PFC circuit 20 operates as a 3-leg boost PFC. Current flowing through inductors 25, 26, and 27 is transferred to PFC link capacitor 24 by the switching operations of first to third switch legs 21, 22, and 23. For example, input terminal IN1 is connected to inductor 25, and inductor 25 and first switch leg 21 operate as a boost PFC. A current flows through inductor 25 due to the voltage at input terminal IN1. The current flowing through inductor 25 charges PFC link capacitor 24 during the on-period of switch Q1, and current flows through inductor L1 and switch Q2 during the off-period of switch Q1 and the on-period of switch Q2.

[0052] FIG. 3 is a circuit diagram for explaining the operation when the AC commercial power supply is single-phase.

[0053] As shown in FIG. 3, a single-phase power supply is transmitted to an input terminal IN1 via an inductor L1.

[0054] The relay control circuit 3 detects that the AC commercial power supply is single-phase, turns on relays RL1, RL4, and RL6, turns off relays RL2 and RL3, and turns on relay RL5 after the peak of the voltage input to the PFC circuit 20.

[0055] When the relay RL1 is turned on, the input terminal IN1 is connected to the first switch leg 21 and the second switch leg 22, and the current flowing through the inductor L1 branches to the first and second switch legs 21, 22, and the first and second switch legs 21, 22 operate in an interleaved manner.

[0056] Relay RL4 is turned on to connect the neutral point N to the third switch leg 23, and relay RL6 is turned on, causing the PFC circuit 20 to perform interleaved full-bridge PFC operation with a single-phase single-inductor structure. That is, relay RL1 is turned on, and the first to third switch legs 21-23 transmit power. The third switch leg 23 is connected to the neutral point N, and the inductor 27 is deactivated by turning on relay RL6.

[0057] 4A to 4D are circuit diagrams illustrating the operation of the PFC circuit when the input power supply is single-phase according to one embodiment.

[0058] 4A and 4B are diagrams showing current paths resulting from the operation of the first to third switch legs 21-23 when the sinusoidal single-phase power supply has a positive voltage. FIGS. 4C and 4D are diagrams showing current paths resulting from the operation of the first to third switch legs 21-23 when the sinusoidal single-phase power supply has a negative voltage. FIGS. 4A and 4C are diagrams showing the power supply operation of the PFC circuit 20, and FIGS. 4B and 4D are diagrams showing the power recovery operation of the PFC circuit 20. As shown in FIG. 4A, while the switches Q1, Q2, and Q6 are in the on state, current flows through the inductors 25 and 26, the switches Q1 and Q2, the capacitors C1 and C2, and the switch Q6 due to the voltage of the single-phase power supply. During this period, power is supplied to the capacitors C1 and C2.

[0059] 4B, while the switches Q4, Q5, and Q6 are in the on state, a current flows through the inductors 25 and 26 and the switches Q4, Q5, and Q6 due to the voltage of the single-phase power supply. During this period, a power recovery operation is performed in which energy is stored in the inductors 25 and 26.

[0060] 4C, during the period when the switches Q3, Q4, and Q5 are in the on state, current flows due to the voltage of the single-phase power supply through the switch Q3, capacitors C1 and C2, switches Q4 and Q5, and inductors 25 and 26. During this period, power is supplied to the capacitors C1 and C2.

[0061] 4D, while the switches Q1, Q2, and Q3 are in the on state, a current flows through the inductors 25 and 26 and the switches Q1, Q2, and Q3 due to the voltage of the single-phase power supply. During this period, a power recovery operation is performed in which energy is stored in the inductors 25 and 26.

[0062] As the driving distance per charge of electric vehicles (EVs) is increasing, there is a demand for increased battery capacity. This has led to demand for large-capacity charging of OBCs (On Board Chargers), necessitating increased charging power.

[0063] Conventional chargers have a two-stage structure consisting of a PFC circuit and a DC / DC converter and can only operate with a single-phase input power supply. To charge with a three-phase input power supply, three chargers must be connected in parallel, one for each phase of the three-phase power supply. This increases the circuit complexity, material costs, and volume / weight. Chargers that only include a PFC circuit implemented with a boost converter have a simple circuit structure, but are unable to charge normally when the battery's required voltage is lower than the input voltage. Buck-boost type chargers can charge across the entire range of output voltage required by the battery, but their control is complex, there are ranges where the AC input voltage is lower than the output voltage, resulting in poor power factor (PF) characteristics. Furthermore, because the boost converter is directly connected to the battery, high output current ripple is applied to the battery, negatively affecting heat generation and battery life.

[0064] The present invention relates to a charging device including a relay network that converts a PFC circuit as a charging system optimized for various AC power supply conditions, i.e., various power supply situations by country. The present invention provides a charging device that can perform charging operations with high charging efficiency in accordance with a wide range of input power supplies and a wide range of battery charging voltages, and has a simpler circuit structure than existing devices.

[0065] In the case of conventional OBCs designed for three-phase input, it was difficult to generate and supply sufficient charging power for single-phase input. For example, conventional OBCs could only supply 3.6 kW of charging power for single-phase input. However, a charging device 1 according to one embodiment can adjust the link voltage supplied to the power conversion circuit 30 using a three-phase, three-leg inverter-type PFC circuit 20. Therefore, the charging device 1 can supply sufficient charging power (e.g., 7.2 kW) to the battery 40 even for single-phase input.

[0066] In addition, because the charging device 1 according to one embodiment can adjust the link voltage, the winding ratio, which is the ratio between the number of windings on one side of the transformers TR1 and TR2 and the number of windings on the other side, can be designed to be close to 1:1. As a result, the charging device 1 can supply power from the battery 40 to a three-phase load or a single-phase load connected to the input terminal of the charging device 1 in a direction opposite to the power supply direction (hereinafter referred to as the forward direction) for charging the battery 40 (hereinafter referred to as the reverse direction).

[0067] Hereinafter, with reference to FIGS. 5 to 7, an operation of the charging device 1 for supplying power from the battery 40 to the load will be described.

[0068] FIG. 5 is a diagram for explaining the operation of the charging device according to one embodiment when supplying power to a three-phase load in the reverse direction.

[0069] Each phase of the three-phase load 50 is shown in Fig. 5 as three inductors 51-53. The inductor 51 is connected between the input terminal IN1 and the neutral point N, the inductor 52 is connected between the input terminal IN2 and the neutral point N, and the inductor 53 is connected between the input terminal IN3 and the neutral point N. Although Fig. 5 shows the three-phase load 50 as three inductors 51-53, the invention is not limited thereto. Each load in the three-phase load 50 may be realized by one of a resistor, an inductor, and a capacitor, or a combination of at least two of them.

[0070] The same components as those in FIG. 1 are denoted by the same reference numerals, and duplicated explanations will be omitted below.

[0071] The relay control circuit 3 detects the load connected to the multiple input terminals IN1-IN3 and determines whether it is a three-phase load or a single-phase load. If the load connected to the multiple input terminals IN1-IN3 is a three-phase load, the relay control circuit 3 generates relay control signals RLS2 and RLS3 that turn on the multiple relays RL2 and RL3 and relay control signals RLS1, RLS4, and RLS6 that turn off the multiple relays RL1, RL4, and RL6, and supplies these signals to the multiple relays RL1, RL4, and RL6. At this time, the relay control circuit 3 can also generate a phase detection signal SL that indicates three phases and transmit it to the power control circuit 4. The relay control circuit 3 turns on relay RL5 when a predetermined period has elapsed since the start of reverse charging.

[0072] The positive terminal (+) and negative terminal (-) of a battery 40 are connected to the two output terminals OUT1 and OUT2, and power is supplied from the battery 40 to the power conversion circuit 30 via the two output terminals OUT1 and OUT2. First, an operation in which power is supplied from the battery 40 to the PFC circuit 20 via the power conversion circuit 30 will be described. Only one of the DC-DC converter 31 and the DC-DC converter 32 can perform a power supply operation. For example, an operation in which the DC-DC converter 31 supplies power from the battery 40 to the PFC circuit 20 will be described. In this case, the switches P5-P8 of the DC-DC converter 32 can be replaced with diodes.

[0073] The voltage between the positive terminal (+) and negative terminal (-) of the battery 40 is supplied as the input voltage to the DC-DC converter 31. When the DC-DC converter 31 converts the input voltage in the reverse direction and supplies it to the PFC circuit 20, all of the switches T1-T4 located on one side are in the off state. The switching operations of the switches T5-T8 located on the other side form a current path via the body diodes of the switches located on one side.

[0074] For example, during the on-period of switches T5 and T8 and the off-period of switches T6 and T7, a resonant current flowing through the other side of transformer TR1 flows through switches T5 and T8, transferring power to one side of transformer TR1. At this time, current flows through the body diodes of switches T1 and T4, supplying power to PFC circuit 20. Next, a dead time occurs during which all switches T5 to T8 are off. After the dead time, during the on-period of switches T6 and T7 and the off-period of switches T5 and T8, a resonant current flowing through the other side of transformer TR1 flows through switches T6 and T7, transferring power to one side of transformer TR1. At this time, current flows through the body diodes of switches T2 and T3, transferring power to PFC circuit 20. Next, a dead time occurs during which all switches T5 to T8 are off. This operation is repeated, and power is supplied from battery 40, connected to the other side of power conversion circuit 30, to PFC circuit 20, connected to one side of power conversion circuit 30.

[0075] The PFC link capacitor 24 is charged with energy supplied from the DC-DC converter 31 and can smooth the voltage input to the PFC circuit 20. The PFC circuit 20 can supply AC power to a three-phase load 50 by the switching operations of the first to third switch legs 21-23. For example, the power control circuit 4 controls the PFC circuit 20 to operate as a three-phase inverter using the phase detection signal SL. That is, the first to third switch legs 21-23 perform switching operations with a phase difference of 120 degrees, and the switching operations of two switches (e.g., Q1 and Q4) in each of the first to third switch legs 21-23 are complementary switching with a phase difference of 180 degrees. The operation of a three-phase inverter is a well-known technique, and a detailed description thereof will be omitted.

[0076] FIG. 6 is a diagram for explaining the operation when the charging device according to the embodiment supplies power to a single-phase load in the reverse direction.

[0077] The single-phase load 60 may be realized by one of a resistor, an inductor, and a capacitor, or a combination of at least two of them. The same components as those in FIG. 1 are designated by the same reference numerals, and redundant descriptions will be omitted below.

[0078] The relay control circuit 3 detects the loads connected to the multiple input terminals IN1-IN3 and determines whether they are three-phase or single-phase loads. If the loads connected to the multiple input terminals IN1-IN3 are single-phase loads, the relay control circuit 3 generates relay control signals RLS1, RLS4, and RLS6 that turn on the multiple relays RL1, RL4, and RL6 and relay control signals RLS2 and RLS3 that turn off the multiple relays RL2 and RL3, and supplies these signals to the multiple relays RL1-RL6. At this time, the relay control circuit 3 can also generate a phase detection signal SL indicating single-phase and transmit it to the power control circuit 4. The relay control circuit 3 turns on relay RL5 when a predetermined period has elapsed since the start of reverse charging.

[0079] The method of supplying power to the PFC circuit 20 via the power conversion circuit 30 is the same as in the embodiment in which a three-phase load is connected, and therefore a detailed description thereof will be omitted. Hereinafter, the operation of the PFC circuit 20 in the embodiment in which a single-phase load 60 is connected will be described with reference to Fig. 7. As shown in Fig. 7, the PFC circuit 20 operates as a single-phase inverter.

[0080] FIG. 7 is a diagram illustrating the switching operation of the PFC circuit according to one embodiment.

[0081] 7, the on-state switches Q1 and Q4 of the first switch leg 21 are shown in the waveform diagram "TON1," the on-state switches Q2 and Q5 of the second switch leg 22 are shown in the waveform diagram "TON2," and the on-state switches Q3 and Q6 of the third switch leg 23 are shown in the waveform diagram "TON3." Under a single-phase load condition, in the third switch leg 23, the switch Q3 is in the off state and the switch Q6 is in the on state.

[0082] During a period T1 in which the switch Q1 is in an ON state and the switch Q4 is in an OFF state in the first switch leg 21, a current flows through the inductor 25 due to the input voltage charged in the PFC link capacitor 24. The current in the inductor 25 flows through the load 60, the relay RL6, and the switch Q6, and power is supplied to the load 60. Next, during a period T2 in which the switch Q1 is in an OFF state and the switch Q4 is in an ON state in the first switch leg 21, the current in the inductor 25 flows through the relay RL6, the switch Q6, and the switch Q4. A dead time exists between the periods T1 and T2 in which the two switches Q1 and Q4 are all in an OFF state.

[0083] During a period T3 in which the switch Q2 is on and the switch Q5 is off in the second switch leg 22, a current flows through the inductor 26 due to the input voltage charged in the PFC link capacitor 24. The current in the inductor 26 flows through the load 60, the relay RL6, and the switch Q6, and power is supplied to the load 60. Next, during a period T4 in which the switch Q4 is off and the switch Q5 is on in the second switch leg 22, a current in the inductor 25 flows through the relay RL6, the switch Q6, and the switch Q5. Between the periods T3 and T4, there is a dead time in which the two switches Q2 and Q5 are all off.

[0084] The charging device 1 according to the embodiment can supply power to a load from the battery 40. The charging device 1 according to the embodiment can be applied to an electric vehicle, and the battery 40 supplies the power required to operate the electric vehicle.

[0085] The charging device according to one embodiment can charge a battery regardless of its rated voltage. The charging device can also supply power from the battery to a load (Vehicle to Load, V2L) or from the battery to a grid (V2G). Furthermore, the frequency variable range of the charging device is narrower than the operating frequency range of the LLC converter, allowing for a smaller transformer. In the PFC circuit according to one embodiment, the current stress on the switches of the PFC circuit is constant regardless of the boost ratio. Therefore, the charging device according to one embodiment can achieve a high boost ratio.

[0086] In particular, when implementing V2G, the link voltage variable method is applied to the charging device, resulting in a very wide range of output voltages that can be supplied to the grid. In addition, the winding ratio is almost the same for reverse and forward power supply, so the resonant gain of the LLC converter does not change. In reverse power supply, power of 380V or more can be supplied without a separate converter on the load side.

[0087] Although the embodiments of the present invention have been described in detail above, the scope of the present invention is not limited to these examples, and various modifications and improvements made by those skilled in the art to which the present invention pertains also fall within the scope of the present invention. [Explanation of symbols]

[0088] 1: Charging device 2: Relay network 3: Relay control circuit 10: AC input filter 20:PFC circuit 30: Power conversion circuit

Claims

1. a PFC (Power Factor Correction) circuit including first to third inductors respectively connected to the first to third input terminals, and first to third switch legs respectively connected to the first to third inductors; a relay network including a plurality of relays; when the first to third input terminals are connected to each phase of a three-phase power supply, the relay network connects each phase of the three-phase power supply to a corresponding one of the first to third switch legs, and the PFC circuit operates as a three-phase boost PFC; When a single-phase power source is connected to any one of the first to third input terminals, the relay network connects the single-phase power source to the first and second switch legs and connects the third switch leg to a neutral point, and the PFC circuit operates as a single-inductor type interleaved single-phase full-bridge PFC having a single inductor structure between one input terminal to which the single-phase power source is connected and the neutral point; The relay network includes: a first relay having one end connected to the first input terminal and the first inductor and another end connected to a second input terminal and a second inductor; a second relay connected between the second input and the second inductor; a third relay connected between the third input terminal and the third inductor; a fourth relay connected between the neutral point and the third inductor; a fifth relay connected in parallel with the third inductor.

2. When the first to third input terminals are connected to respective phases of a three-phase power supply, The charging device according to claim 1 , wherein the first relay, the fourth relay, and the fifth relay are turned off, and the second relay and the third relay are turned on.

3. When a single-phase power source is connected to the first input terminal, The charging device according to claim 1 , wherein the first relay, the fourth relay, and the fifth relay are turned on, and the second relay and the third relay are turned off.

4. The relay network includes: a sixth relay connected in parallel with a resistor connected between the first input terminal and the first inductor; The charging device is The charging device according to claim 3 , wherein the sixth relay is turned on after a peak of the voltage input to the PFC circuit occurs.

5. The charging device of claim 1 , further comprising a power conversion circuit coupled between the PFC circuit and a battery to transfer power from the battery to the PFC circuit.

6. the first switch leg includes a first switch coupled between the first inductor and a first input terminal of the power conversion circuit, and a second switch coupled between the first inductor and a second input terminal of the power conversion circuit; the second switch leg includes a third switch coupled between the second inductor and a first input of the power conversion circuit, and a fourth switch coupled between the second inductor and a second input of the power conversion circuit; 6. The charging device of claim 5, wherein the third switch leg includes a fifth switch coupled between the third inductor and a first input terminal of the power conversion circuit, and a sixth switch coupled between the third inductor and a second input terminal of the power conversion circuit.

7. When a single-phase power source is connected to the first input terminal, turning on the first relay, the fourth relay, and the fifth relay, and turning off the second relay and the third relay; a period in which the first switch, the third switch, and the sixth switch are in an on state and a period in which the second switch, the fourth switch, and the sixth switch are in an on state are repeated during a period in which the single-phase power supply has a positive voltage; 7. The charging device according to claim 6, wherein, during a period in which the single-phase power supply has a negative voltage, a period in which the second switch, the fourth switch, and the fifth switch are in an on state and a period in which the first switch, the third switch, and the fifth switch are in an on state are repeated.

8. The relay network includes: a sixth relay connected in parallel with a resistor connected between the first input terminal and the first inductor; The charging device is The charging device according to claim 1 , wherein the sixth relay is turned on after a peak of the voltage input to the PFC circuit.

9. 2. The charging device of claim 1, further comprising a relay control circuit connected to the first to third input terminals, detecting an input terminal to which a power source is connected among the first to third input terminals, and controlling the relay network.

10. a PFC (Power Factor Correction) circuit including first to third inductors respectively connected to the first to third input terminals, and first to third switch legs respectively connected to the first to third inductors; a relay network including a plurality of relays; a power conversion circuit coupled between the PFC circuit and a battery to transfer power from the battery to the PFC circuit; when the first to third input terminals are connected to respective phases of a three-phase load, the relay network connects each phase of the three-phase load to a corresponding one of the first to third switch legs, and the PFC circuit operates as a three-phase inverter; when a single-phase load is connected to any one of the first to third input terminals, the relay network connects the single-phase load to the first and second switch legs and connects the third switch leg to a neutral point, and the PFC circuit operates as a single-phase inverter; The relay network includes: a first relay having one end connected to the first input terminal and the first inductor and another end connected to a second input terminal and a second inductor; a second relay connected between the second input and the second inductor; a third relay connected between the third input terminal and the third inductor; a fourth relay connected between the neutral point and the third inductor; a fifth relay connected in parallel with the third inductor.

11. When the first to third input terminals are connected to respective phases of a three-phase load, The charging device according to claim 10, wherein the first relay, the fourth relay, and the fifth relay are turned off, and the second relay and the third relay are turned on.

12. When a single-phase load is connected to the first input terminal, The charging device according to claim 10, wherein the first relay, the fourth relay, and the fifth relay are turned on, and the second relay and the third relay are turned off.

13. 11. The charging device of claim 10, further comprising a relay control circuit connected to the first to third input terminals, detecting an input terminal to which a load is connected among the first to third input terminals, and controlling the relay network.

14. the first switch leg includes a first switch coupled between the first inductor and a first input terminal of the power conversion circuit, and a second switch coupled between the first inductor and a second input terminal of the power conversion circuit; the second switch leg includes a third switch coupled between the second inductor and a first input of the power conversion circuit, and a fourth switch coupled between the second inductor and a second input of the power conversion circuit; 11. The charging device of claim 10, wherein the third switch leg includes a fifth switch coupled between the third inductor and a first input terminal of the power conversion circuit, and a sixth switch coupled between the third inductor and a second input terminal of the power conversion circuit.

15. When a single-phase load is connected to the first input terminal, turning on the first relay, the fourth relay, and the fifth relay, and turning off the second relay and the third relay; the first switch and the second switch alternately switch on and off, the third switch and the fourth switch alternately switch on and off, an on period of the first switch overlaps with an entire on period of the fourth switch, and an on period of the third switch overlaps with an entire on period of the second switch, The charging device according to claim 14 , wherein the fifth switch is in an off state and the sixth switch is in an on state.

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