Charging and discharging devices and electric vehicle chargers

Abstract

The charging / discharging device is connected to a power grid through a first cable and a plug, and to an electric vehicle through a second cable and a connector. The charging / discharging device includes a charging circuit, a reverse flow circuit, and a controller, where the charging circuit provides a charging path that supplies power from the power grid from the plug to the connector, and the reverse flow circuit provides a reverse flow path that supplies power from the connector to the plug. In a charging mode, the controller sets a first current through the charging path, and in a reverse flow mode, the controller sets a second current through the reverse flow path. The present disclosure also relates to a charger for an electric vehicle.

Description

[Technical Field]

[0001] The present disclosure relates to a charging / discharging device and an electric vehicle charger, and more particularly to a portable charging / discharging device and an electric vehicle charger. [Background technology]

[0002] Currently, electric vehicles are transitioning from fuel-powered to electric-powered vehicles in order to conserve energy and reduce carbon emissions. Electric vehicles (generally referred to as electric cars) are powered by batteries, which require charging to maintain their driving range. Electric vehicle chargers typically have the configurations shown in FIGS. 1A to 1C. The charging technology shown in FIG. 1A uses a simple extension cord from a standard power outlet for home charging. In particular, this type of electric vehicle charger 100 connects an electric vehicle 300 to a standard household outlet 200A to supply power. The electric vehicle charger 100 typically includes a single cable for connecting the electric vehicle 300 to the outlet 200A. Due to its simple structure, this type of electric vehicle charger 100 is generally suitable for light vehicles (e.g., electric motorcycles).

[0003] The charging technology shown in FIG. 1B involves charging the electric vehicle 300 using a dedicated charging station or a home wall-mounted charging box (collectively referred to as the grid-side charging device 100B). Because the connection cable is provided by the grid-side charging device 100B, the electric vehicle 300 does not need a dedicated cable for charging, and this has become the mainstream of home charging. On the other hand, the charging technology shown in FIG. 1C is commonly referred to as "DC fast charging" or simply "fast charging." This type of charging typically involves a charging station 100C and can provide high-power charging. Specifically, such an electric vehicle charger 100 typically supplies DC power to charge the electric vehicle 300, with currents reaching hundreds of amperes and powers reaching hundreds of kilowatts.

[0004] However, current electric vehicle chargers 100 only support technology for charging electric vehicles and do not have technology for supplying power to the power grid. Meanwhile, the electric vehicle charger 100 shown in FIG. 1B is fixed to a home or a specific location and is not mobile, so it cannot effectively support the power grid. Therefore, the inventors of the present disclosure are investigating how to design a portable charging / discharging device and an electric vehicle charger that combines the advantages of both and eliminates their drawbacks, as well as how to more easily feed power from electric vehicles back to the power grid and provide bidirectional charging functionality. Summary of the Invention

[0005] The present disclosure provides a charging / discharging device that solves the above-mentioned problems and overcomes the drawbacks of the prior art. The charging / discharging device of the present disclosure is connected to a power grid through a first cable and a plug and to an electric vehicle through a second cable and a connector. The charging / discharging device includes a charging circuit, a reverse flow circuit, and a controller, and the charging circuit and the reverse flow circuit are connected to the first cable and the second cable, respectively. The charging circuit provides a charging path that supplies power from the power grid from the plug to the connector, and the reverse flow circuit provides a reverse flow path that reversely flows vehicle power from the connector to the plug. The controller is connected to the charging circuit and the reverse flow circuit and transmits current information and operation commands to and from the electric vehicle through the second cable. Based on the operation commands, the controller determines whether the electric vehicle operates in a charging mode or a reverse flow mode. In the charging mode, the controller sets a first current flowing through the charging path and charges the electric vehicle based on the first current. In the reverse flow mode, the controller sets a second current flowing through the reverse flow path and reversely flows power to the power grid based on the second current.

[0006] The present disclosure provides an electric vehicle charger that solves the above-mentioned problems and overcomes the drawbacks of the prior art. Accordingly, the portable electric vehicle charger of the present disclosure includes a plug, a first cable, a second cable, and a charging / discharging device. The first cable is connected to the plug, and the second cable is connected to the connector. The charging / discharging device is connected to the first and second cables and includes a charging circuit and a reverse flow circuit. The charging circuit is connected to the first and second cables and includes a first transfer switch. The charging circuit provides a charging path for supplying grid power from the plug to the connector, with one end of the first transfer switch connected to the first cable and the other end of the first transfer switch connected to the second cable. The reverse flow circuit is connected to the first and second cables and includes a second transfer switch, a conversion circuit, and a third transfer switch. The reverse flow circuit provides a reverse flow path for supplying vehicle power from the connector to the plug, with one end of the second transfer switch connected to the first cable and one end of the conversion circuit connected to the second transfer switch. One end of the third changeover switch is connected to the other end of the conversion circuit, and the other end of the third changeover switch is connected to the second cable.

[0007] A main object and effect of the present disclosure is that the electric vehicle charger of the present disclosure can provide a bidirectional charging function, i.e., the charge and discharge operations of the electric vehicle charger can not only charge the electric vehicle using power supplied from the power grid, but also feed back vehicle power supplied from the electric vehicle to the power grid, thereby realizing a bidirectional power supply.

[0008] For a deeper understanding of the present disclosure, the techniques, means, and effects adopted by the present disclosure to achieve the specified objects can be seen in the following detailed description and the accompanying drawings, which are intended to provide a more concrete understanding of the objects, features, and characteristics of the present disclosure. Note that the accompanying drawings are for reference and explanation purposes only and are not intended to limit the present disclosure. [Brief explanation of the drawings]

[0009] [Figure 1A] FIG. 1 is a configuration diagram of a first embodiment of a conventional electric vehicle charger. [Figure 1B] FIG. 10 is a configuration diagram of a second embodiment of a conventional electric vehicle charger. [Figure 1C] FIG. 10 is a configuration diagram of a third embodiment of a conventional electric vehicle charger. [Figure 2] FIG. 2 is a circuit block diagram of the portable electric vehicle charger of the present disclosure. [Figure 3] FIG. 2 is a more detailed circuit block diagram of the portable electric vehicle charger of the present disclosure. [Figure 4A] FIG. 2 is a schematic diagram showing the current direction in the charging mode of the portable electric vehicle charger of the present disclosure. [Figure 4B] FIG. 1 is a schematic diagram illustrating the current direction in a reverse flow mode of the portable electric vehicle charger of the present disclosure. [Figure 5] FIG. 2 is a more detailed circuit block diagram of the portable electric vehicle charger of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0010] The technical contents and detailed description of the present disclosure will be described below with reference to the drawings.

[0011] FIG. 2 is a circuit block diagram of a portable electric vehicle charger according to the present disclosure, and should be referred to in conjunction with FIGS. 1A to 1C. A portable electric vehicle charger 100 according to the present disclosure (hereinafter simply referred to as electric vehicle charger 100) is connected to a power grid 200 and an electric vehicle 300, and includes a plug 1, a first cable 2, a second cable 3, a charging / discharging device 4, and a connector 5. The plug 1 is connected to the power grid 200 by being inserted into an outlet 200A, and the connector 5 is connected to the electric vehicle 300 by being inserted into a connector 300A of the electric vehicle 300. One end of the first cable 2 is connected to the plug 1, and the other end of the first cable 2 is connected to one end of the charging / discharging device 4. One end of the second cable 3 is connected to the connector 5, and the other end of the second cable 3 is connected to the other end of the charging / discharging device 4. Here, the electric vehicle charger 100 does not include the power grid-side charging device 100B shown in FIG. 1B or the charging stand 100C shown in FIG. 1C, but uses a conventional plug 1 (e.g., US standard, European standard, etc.) to connect to a general outlet 200A and obtain power grid power Pac.

[0012] Furthermore, a main object and effect of the present disclosure is that the electric vehicle charger 100 of the present disclosure can provide a bidirectional charging function. That is, the charging and discharging operations of the electric vehicle charger 100 not only enable charging of the electric vehicle 300 using power grid power Pac supplied from the power grid 200, but also enable feeding back vehicle power Pv supplied from the electric vehicle 300 to the power grid 200. Here, the charging and discharging device 4 has a charging path Lc and a reverse flow path Lf. When the electric vehicle 300 is charged by power grid power Pac, the power grid power Pac is supplied to the electric vehicle 300 via the plug 1, the first cable 2, the charging path Lc of the charging and discharging device 4, the second cable 3, and the connector 5. Conversely, when vehicle power Pv is fed back to the power grid 200, the vehicle power Pv is fed back to the power grid 200 via the connector 5, the second cable 3, the reverse flow path Lf of the charging and discharging device 4, the first cable 2, and the plug 1. The plug 1, first cable 2, charging / discharging device 4, second cable 3, and connector 5 can be configured as an integrated electric vehicle charger 100 or as a separate electric vehicle charger 100. Specifically, in the case of a separate electric vehicle charger 100, the plug 1 and first cable 2 have a modular structure, and the connection between the first cable 2 and the charging / discharging device 4 is a detachable (replaceable) connection structure. The charging / discharging device 4 receives specification information Is of the plug 1 through the first cable 2, and this specification information Is is determined based on the type of plug 1 currently connected to the charging / discharging device 4 through the first cable 2. In addition, the charging / discharging device 4 can transmit current information Ic and an operation command Co through the second cable 3 and the electric vehicle 300. Here, based on the standard information Is, the charging / discharging device 4 can obtain information such as whether the currently connected plug 1 complies with the relevant standard for the electric vehicle charger 100, the specifications of the plug 1 (US standard, European standard, etc.), the voltage of the power grid (three-phase / single-phase, 110V / 220V), the upper limit of the current (usually determined according to the voltage), the frequency, and the phase.

[0013] Meanwhile, by transmitting the current information Ic, the electric vehicle 300 and the charging / discharging device 4 can confirm and set the current that the electric vehicle 300 can charge and discharge. The operation command Co is mainly used by the electric vehicle 300 and the charging / discharging device 4 to mutually grasp their current operating states. For example, by using the operation command Co, the electric vehicle 300 and the charging / discharging device 4 can confirm whether the electric vehicle 300 is properly connected to the charging / discharging device 4 and whether the plug 1 is properly inserted into the outlet 200A, and determine whether the electric vehicle 300 is in a standby state, but this is not limitative. Furthermore, by transmitting the operation command Co, the charging / discharging device 4 can determine in which mode the electric vehicle 300 is to operate (e.g., charging mode or reverse flow mode) and selectively provide a corresponding path (i.e., providing a charging path Lc in the charging mode and providing a reverse flow path Lf in the reverse flow mode) to perform an appropriate operation.

[0014] After plug 1 is inserted into outlet 200A, charging / discharging device 4 can receive specification information Is of plug 1 through first cable 2. In the charging mode operation, charging / discharging device 4 first checks whether electric vehicle 300 is properly connected to connector 5 and whether plug 1 is properly inserted into outlet 200A. If both are properly connected, the operation command Co instructs the charging / discharging device 4 to enter a standby state, and the electric vehicle 300 and the charging / discharging device 4 can recognize that the current state is a standby state from the instruction of the operation command Co. Thereafter, the value of the operation command Co is adjusted according to the request of the electric vehicle 300, and the charging / discharging device 4 determines whether the electric vehicle 300 is to operate in a charging mode or a reverse power flow mode based on the value of the operation command Co.

[0015] Here, the charging path Lc is connected in parallel to the reverse flow path Lf, and the charging path Lc and the reverse flow path Lf are not the same (are independent of each other), and the current flows in opposite directions. In the charging mode, the charging / discharging device 4 forms the charging path Lc and blocks the reverse flow path Lf to prevent the current on the charging path Lc from flowing to the reverse flow path Lf and consuming excess power. On the other hand, in the reverse flow mode, the charging / discharging device 4 blocks the charging path Lc and forms the reverse flow path Lf, and converts the vehicle power Pv to the power grid power Pac through the reverse flow path Lf. When the reverse flow path Lf converts the vehicle power Pv to the power grid power Pac, the reverse flow path Lf can convert the three-phase or single-phase vehicle power Pv to the three-phase or single-phase power grid power Pac. For example, the reverse flow path Lf can convert three-phase vehicle power Pv into single-phase power grid power Pac, or convert single-phase vehicle power Pv into three-phase power grid power Pac, but is not limited to this. In this way, adaptive power conversion can be performed according to the demands of the power grid 200 and the electric vehicle 300, and unavailability due to differences in the wiring between the two can be avoided.

[0016] The operation command Co is preferably a voltage value, and adjusting the voltage value can set the current operation state of the charging / discharging device 4. For example, if the electric vehicle 300 is not properly connected to the connector 5 or if the plug 1 is not properly inserted into the outlet 200A, the voltage value of the operation command Co becomes a specific value (e.g., 0 V, but not limited to this), and based on this specific value, the electric vehicle 300 can know that the charging / discharging device 4 is not in a standby state. Conversely, if the voltage value (e.g., 5 V, but not limited to this) becomes a specific value, the electric vehicle 300 can know that the charging / discharging device 4 is in a standby state.

[0017] Furthermore, when the electric vehicle 300 is to be operated in the charging mode or the reverse flow mode, the electric vehicle 300 can set the mode by adjusting the value of the operation command Co. For example, when a typical charging / discharging device 4 is in a standby state (as in the above example, the value of the operation command Co is 5V), the standby state is preset to the charging mode. Conversely, after the charging / discharging device 4 is in a standby state, the electric vehicle 300 can notify the charging / discharging device 4 that it needs to operate in the reverse flow mode by adjusting the value of the operation command Co (for example, but not limited to, the electric vehicle 300 changes the value of the operation command Co from 5V to 3V). Here, the operation command Co is not limited to a voltage value and can be, for example, a digital signal (for example, but not limited to, a logic 0 to 11 corresponds to the reverse flow mode) or a pulse width modulation signal (PWM). The operation mode can also be adjusted by the duty ratio (DUTY) (for example, but not limited to, a duty ratio of 50% corresponds to the reverse flow mode). A detailed description of such a method will be omitted here.

[0018] Taking the charging mode as an example, when the charging / discharging device 4 is connected to the plug 1 via the first cable 2, the charging / discharging device 4 receives the specification information Is of the plug 1 via the first cable 2, and thereby knows the upper limit (e.g., 18 A, but not limited thereto; this value typically varies depending on the voltage of the power grid and the allowable current of the plug 1) of the charging / discharging device 4's charging current. The charging / discharging device 4 then adjusts the current information Ic based on the upper limit of the charging current, and the current information Ic corresponds to the first current I1 flowing through the charging path Lc (typically, a preset upper limit). When the charging / discharging device 4 is connected to the electric vehicle 300 via the second cable 3, the charging / discharging device 4 communicates with the electric vehicle 300 by transmitting the current information Ic to notify the electric vehicle 300 of the upper limit of the current flowing through the charging path Lc. Thereafter, the electric vehicle 300 adjusts the current information Ic to ultimately determine the first current I1 for charging (for example, after the charging / discharging device 4 notifies the electric vehicle 300 of an upper limit value of 18 A, the electric vehicle 300 ultimately selects 15 A for charging, but this is not limiting). Finally, the charging / discharging device 4 sets the first current I1 that flows through the charging path Lc based on the adjusted current information Ic.

[0019] Here, the current information Ic is preferably a pulse-width modulation (PWM) signal, and the magnitude of the first current I1 can be changed by adjusting the duty ratio (for example, a duty ratio of 30% corresponds to the first current I1 of 18 A), but is not limited thereto. The current information Ic can also indicate the magnitude of the first current I1 as a digital signal (for example, but not limited to, a logic 0-11 corresponds to the first current I1 of 18 A) or a voltage value (for example, but not limited to, a voltage of 5 V corresponds to the first current I1 of 18 A). Similarly, other methods are possible, but detailed description thereof will be omitted here. Finally, after the operation mode and the first current I1 are determined, the charging / discharging device 4 provides the corresponding charging path Lc, performs charging operation, and charges the electric vehicle 300 based on the first current I1. Meanwhile, after the operation command Co instructs the charging / discharging device 4 to enter a standby state, the charging / discharging device 4 sets the second current I2 flowing through the reverse flow path Lf according to the current information Ic. Furthermore, after the operation mode and the second current I2 are determined, the charging / discharging device 4 provides a corresponding reverse flow path Lf to perform power supply operation and perform reverse power flow to the power grid 200 according to the second current I2. In addition, the operations of other reverse flow modes are similar to those of the charging mode described above, and therefore will not be described in detail here.

[0020] FIG. 3 is a more detailed circuit block diagram of the portable electric vehicle charger of the present disclosure and should be referred to in conjunction with FIG. 2. FIG. 3 illustrates a preferred embodiment based on the configuration of FIG. 2, but is not limited thereto. As shown in FIG. 3, the charging / discharging device 4 includes a charging circuit 42, a reverse flow circuit 44, and a controller 46. The charging circuit 42 is connected in parallel with the reverse flow circuit 44. The charging circuit 42 is connected to the first cable 2 and the second cable 3 and provides a charging path Lc for supplying grid power Pac from the plug 1 to the connector 5. The reverse flow circuit 44 is connected to the first cable 2 and the second cable 3 and provides a reverse flow path Lf for supplying vehicle power Pv from the electric vehicle 300 to the plug 1 via the connector 5. The controller 46 is connected to the charging circuit 42 and the reverse flow circuit 44 and includes a protection pin, an identification pin, a control pilot pin CP, and a proximity pilot pin PP. The identification pin and the protection pin are connected to the plug 1 through a first cable 2, and the plug 1 may preferably include a thermistor (NTC) and a detection resistor R (Recognize Resistance).

[0021] The protection pin is connected to the thermistor NTC through the first cable 2 and determines whether to perform overtemperature protection for the charging / discharging device 4 based on a change in the resistance value of the thermistor NTC. The identification pin is connected to the detection resistor R through the first cable 2, thereby allowing the controller 46 to obtain specification information Is through the detection resistor R. Therefore, if the plug 1 uses the detection resistor R, the identification pin can, for example, provide a constant current source to generate a specific voltage across the detection resistor R, and this specific voltage becomes the specification information Is, but is not limited to this. The control pilot pin CP is connected to the electric vehicle 300 through the second cable 3. The control pilot pin CP and the electric vehicle 300 mutually transmit current information Ic, thereby allowing the controller 46 and the electric vehicle 300 to set and adjust a first current I1 flowing through the charging path Lc based on the current information Ic and charge the electric vehicle 300 based on the first current I1, or to set and adjust a second current I2 flowing through the reverse flow path Lf based on the current information Ic and perform reverse power flow to the power grid 200 based on the second current I2. The proximity pilot pin PP is connected to the electric vehicle 300 via the second cable 3, and the proximity pilot pin PP and the electric vehicle 300 transmit operation commands Co to each other, whereby the controller 46 and the electric vehicle 300 determine the current operating state based on the operation commands Co.

[0022] In one embodiment, the controller 46 is a control chip, and may be a microcontroller, a signal processor, or the like. Alternatively, the controller 46 may be a control circuit configured with circuits and logic gates. The controller 46 shown in FIG. 3 may include not only a control chip but also circuits and electronic components (e.g., an analog-to-digital conversion circuit, resistors, etc.) that detect and transmit signals. Since these circuits and electronic components are not a key feature of the present disclosure, detailed description thereof will be omitted. Meanwhile, the controller may have wireless communication capabilities, including, but not limited to, Wi-Fi, Bluetooth (registered trademark), and mobile communications (2G / 3G / 4G / 5G, etc.). In this way, the portable electric vehicle charger can be equipped with a function for communicating with the outside world.

[0023] Here, the charging circuit 42 includes a first change-over switch SW1. One end of the first change-over switch SW1 is connected to the first cable 2, and the other end is connected to the second cable 3. A controller 46 is connected to a control end of the first change-over switch SW1 and provides a control signal to control the conduction / cut-off of the first change-over switch SW1. In the charging mode, the controller 46 turns on the first change-over switch SW1, thereby forming the charging circuit 42 and providing a charging path Lc. On the other hand, when the controller 46 cuts off the first change-over switch SW1 (for example, in a standby state or a reverse power flow mode), both ends of the charging circuit 42 are cut off, preventing current from being erroneously supplied from the power grid 200 to the electric vehicle 300. Note that the first change-over switch SW1 is preferably a switch through which a large current flows, such as a relay, and it is desirable that no leakage current occurs when the switch is cut off and that the switch can be implemented with a simple configuration.

[0024] The charging / discharging device 4 further includes an auxiliary circuit 48, which is connected to a path between the first transfer switch SW1 and the first cable 2. Whether the charging / discharging device 4 is operating in standby mode, charging mode, or reverse flow mode, the auxiliary circuit 48 converts the power grid power Pac into operating power Pcc and continues to supply power to the controller 46 after the plug 1 is connected to the power grid 200. Generally, since the controller 46 is a device that receives DC power, the auxiliary circuit 48 may be a converter that converts AC to DC. More preferably, the auxiliary circuit 48 can connect the power grid power Pac to the path between the first transfer switch SW1 and the first cable 2, for example, by connecting an isolation transformer, and electrically isolate the controller 46 from the main power supply path.

[0025] Meanwhile, the reverse power flow circuit 44 includes a second change-over switch SW2, a conversion circuit 442, and a third change-over switch SW3. One end of the second change-over switch SW2 is connected to the first cable 2, and the other end of the second change-over switch SW2 is connected to the conversion circuit 442. One end of the third change-over switch SW3 is connected to the other end of the conversion circuit 442, and the other end of the third change-over switch SW3 is connected to the second cable 3. The controller 46 is connected to the control ends of the second change-over switch SW2 and the third change-over switch SW3, and provides control signals to control the conduction / cut-off of the second change-over switch SW2 and the third change-over switch SW3. In the reverse power flow mode, the controller 46 turns on the second change-over switch SW2 and the third change-over switch SW3 and activates the conversion circuit 442, thereby forming a reverse power flow path Lf. As a result, the vehicle power Pv is supplied to the conversion circuit 442 via the third change-over switch SW3, and after the conversion circuit 442 converts the vehicle power Pv into power grid power Pac, it is supplied to the plug 1 via the second change-over switch SW2. Here, the three-phase or single-phase vehicle power Pv can be converted into three-phase or single-phase power grid power Pac. When the controller 46 turns off the second change-over switch SW2 and the third change-over switch SW3 and disables the conversion circuit 442 (for example, in standby mode or charging mode), both ends of the reverse flow circuit 44 are cut off, preventing current from being erroneously supplied from the electric vehicle 300 to the power grid 200.

[0026] Furthermore, the conversion circuit 442 preferably includes an AC-DC conversion circuit AC / DC, a DC-AC conversion circuit DC / AC, and a storage capacitor (not shown). One end of the AC-DC conversion circuit AC / DC is connected to the third transfer switch SW3, and the other end is connected to the storage capacitor (not shown). One end of the DC-AC conversion circuit DC / AC is connected to the storage capacitor (not shown), and the other end is connected to the second transfer switch SW2. The controller 46 controls the AC-DC conversion circuit AC / DC to convert the vehicle power Pv into DC power Pdc and store the DC power Pdc in the storage capacitor (not shown). Thereafter, the controller 46 controls the DC-AC conversion circuit DC / AC to convert the DC power Pdc into power grid power Pac and perform reverse power flow to the power grid 200.

[0027] Because the conversion circuit 442 includes a storage capacitor (not shown), the conversion circuit 442 can arbitrarily convert three-phase / single-phase power. Preferably, the AC / DC conversion circuit AC / DC converts the three-phase vehicle power Pv into DC power Pdc, and the DC / AC conversion circuit DC / AC further converts the DC power Pdc into single-phase power grid power Pac. Alternatively, the AC / DC conversion circuit AC / DC converts the single-phase vehicle power Pv into DC power Pdc, and the DC / AC conversion circuit DC / AC further converts the DC power Pdc into three-phase power grid power Pac. This makes it possible to realize adaptive power conversion in response to the requirements of the power grid 200 and the electric vehicle 300, and to avoid unusable situations due to differences in the wiring between the two. Note that in one embodiment, the AC / DC conversion circuit AC / DC and the DC / AC conversion circuit DC / AC may be conversion circuits without isolation transformers (e.g., conversion circuits without isolation transformers at the input and output ends of a buck, boost, etc.). The reason for this is, but is not limited to, that the magnitudes of the voltage and current at both ends of the conversion circuit 442 are similar, eliminating the need to use a large isolation transformer. Furthermore, a configuration may be adopted in which the storage capacitor and its DC stage (which may be, but is not limited to, a current source type or matrix type AC / AC converter, for example) are not included between the AC-DC conversion circuit AC / DC and the DC-AC conversion circuit DC / AC, thereby reducing the space occupied by the storage capacitor.

[0028] FIG. 4A is a schematic diagram showing the current direction in the charging mode of the portable electric vehicle charger of the present disclosure, and should be seen in conjunction with FIGS. 2 and 3. FIG. 4A illustrates the current flow in the charging mode, with the arrow A1 indicating the direction of the first current I1. Specifically, when plug 1 is inserted into outlet 200A, auxiliary circuit 48 receives power grid power Pac, converts the power grid power Pac into operating power Pcc, and supplies the power to controller 46. After controller 46 is powered and begins operating normally, controller 46 receives specification information Is of plug 1 via first cable 2, and thereby obtains upper limits of the charging current (i.e., first current I1) and the power supply current (i.e., second current I2) of charging / discharging device 4 (these upper limits typically vary depending on the voltage of the power grid and the allowable current of plug 1).

[0029] When the controller 46 confirms that the electric vehicle 300 is properly connected to the connector 5 and that the plug 1 is properly inserted into the outlet 200A, the controller 46 adjusts the value of the operation command Co to instruct the charging / discharging device 4 to enter a standby state. In the standby state, the controller 46 determines whether the electric vehicle 300 is to operate in a charging mode or a reverse flow mode based on the value of the operation command Co. In addition, in the standby state, the controller 46 can set the first current I1 and the second current I2 that flow through the charging path Lc based on the current information Ic. When the controller 46 determines that the operating mode is the charging mode and has completed setting the magnitude of the first current I1 (by transmitting the current information Ic to and from the electric vehicle 300), the controller 46 turns on the first change-over switch SW1, thereby forming a charging path using the charging circuit 42.

[0030] FIG. 4B is a schematic diagram illustrating the current direction in the reverse flow mode of the portable electric vehicle charger of the present disclosure, and should be viewed in conjunction with FIGS. 2 to 4A. FIG. 4B illustrates the current flow in the reverse flow mode, with arrow A2 indicating the direction of the second current I2. The difference between FIG. 4A and FIG. 4B is that when the controller 46 determines that the operating mode is the reverse flow mode and completes setting of the magnitude of the second current I2 (by transmitting current information Ic to and from the electric vehicle 300), the controller 46 turns on the second and third changeover switches SW2 and SW3 and activates the conversion circuit 442, thereby forming the reverse flow path Lf. Note that, in one embodiment, the operation method not described in FIG. 4B is similar to that in FIG. 4A, and therefore will not be described in detail here.

[0031] FIG. 5 is a more detailed circuit block diagram of the portable electric vehicle charger of the present disclosure, and should be referenced in conjunction with FIGS. 2 to 4B. In addition to the elements described above in FIGS. 2 to 4B, FIG. 5 also includes multiple drivers, detectors (circuits), and the like. These circuits are primarily intended to protect the electric vehicle charger 100 and are not a key feature of the present disclosure, so detailed descriptions of each circuit will be omitted. Therefore, the electric vehicle charger 100 of the present disclosure is equipped with protection functions such as leakage current, overcurrent, voltage, frequency, and ground detection during charging and power supply, ensuring the safety of users, electric vehicles, homes, and commercial power sources. Additionally, in FIG. 5, the second transfer switch SW2 preferably includes a first switch Q1 and a second switch Q2 connected in series, and the third transfer switch SW3 preferably includes a third switch Q3 and a fourth switch Q4 connected in series. When the controller 46 turns on the second transfer switch SW2, the first switch Q1 and the second switch Q2 also turn on; conversely, when the controller 46 turns off the second transfer switch SW2, both switches turn off. The purpose and effect of providing the second changeover switch SW2 with the first switch Q1 and second switch Q2 connected in series is to provide a shutoff function that can back up each other.

[0032] Specifically, when terminating the reverse power flow mode, the controller 46 turns off the second transfer switch SW2. If the second transfer switch SW2 fails and is unable to shut down properly, grid power Pac may be erroneously supplied to the conversion circuit 442. However, due to the backup functions of the first switch Q1 and the second switch Q2, even if one of them fails and is unable to shut down properly, the other switch can function as a backup and successfully shut down the path from the first cable 2 to the conversion circuit 442. Similarly, when the controller 46 turns on the third transfer switch SW3, the third switch Q3 and the fourth switch Q4 also conduct, and conversely, when the controller 46 turns off the third transfer switch SW3, both switches are shut down. The operation method and effect are similar to those of the second transfer switch SW2, so a detailed description will be omitted here.

[0033] Although the preferred embodiments of the present disclosure have been described in detail above with reference to the accompanying drawings, the features of the present disclosure are not limited thereto and are not intended to limit the present disclosure. The technical scope of the present disclosure is based on the following claims, and embodiments that conform to the spirit and to which similar modifications have been made are also included in the technical scope of the present disclosure. Furthermore, variations and modifications that can be easily conceived by those skilled in the art within the technical scope of the present disclosure are also included in the scope of the claims. [Explanation of symbols]

[0034] 100B: Power grid side charging device 100C: Charging stand 100: Electric vehicle charger 1:Plug NTC: Thermistor R: detection resistor 2: First cable 3: Second cable 4: Charge / discharge device 42:Charging circuit SW1: 1st changeover switch 44: Reverse power flow circuit SW2: Second selector switch Q1: First switch Q2: Second switch SW3: Third switch Q3: Third switch Q4: 4th switch 442: Conversion circuit AC / DC: AC / DC conversion circuit DC / AC: DC / AC conversion circuit 46: Controller 48: Auxiliary circuit CP: Control pilot pin PP: Proximity pilot pin 5: Connector Lc: Charging path I1: 1st current Lf: Reverse power flow path I2: 2nd current 200: Power grid 200A: Outlet 300: Electric vehicles 300A: Connector Pac: Power grid power Pv: Vehicle power Pcc: Operating power Pdc: Direct current power Is:Standard information Ic: Current information Co: Operation command A1, A2: Arrow direction

Claims

1. A charging / discharging device connected to a power grid through a first cable and a plug, and connected to an electric vehicle through a second cable and a connector, a charging circuit connected to the first cable and the second cable, the charging circuit providing a charging path that supplies grid power from the plug to the connector; a reverse flow circuit connected to the first cable and the second cable and providing a reverse flow path for reverse flow of vehicle power from the connector to the plug; a controller connected to the charging circuit and the reverse flow circuit, transmitting current information and an operation command to the electric vehicle through the second cable, and determining whether the electric vehicle is to operate in a charging mode or a reverse flow mode based on the operation command; In the charging mode, the controller sets a first current flowing through the charging path and charges the electric vehicle based on the first current, and in the reverse flow mode, the controller sets a second current flowing through the reverse flow path and performs reverse power flow to the power grid based on the second current.

2. 2. The charging / discharging device of claim 1, wherein the plug and the first cable have a modular structure, the first cable and the charging / discharging device are connected in a detachable manner, and the controller receives specification information of the plug through the first cable, provides the current information based on the specification information, and sets the first current and the second current based on the current information.

3. the charging circuit includes a first changeover switch having one end connected to the first cable and the other end connected to the second cable; 2. The charging / discharging device according to claim 1, wherein in the charging mode, the controller causes the first changeover switch to be conductive to form the charging path.

4. further comprising an auxiliary circuit connected to the first changeover switch and the first cable; The charging / discharging device according to claim 3 , wherein in the charging mode or the reverse flow mode, the auxiliary circuit converts the power grid power into operating power to power the controller.

5. The reverse flow circuit includes: a second changeover switch having one end connected to the first cable; a conversion circuit having one end connected to the second changeover switch; a third changeover switch having one end connected to the other end of the conversion circuit and the other end connected to the second cable; The charging / discharging device according to claim 1 , wherein in the reverse flow mode, the controller causes the second changeover switch and the third changeover switch to be conductive, activates the conversion circuit, and forms the reverse flow path.

6. 6. The charging / discharging device according to claim 5, wherein the second changeover switch includes a first switch and a second switch connected in series, and the third changeover switch includes a third switch and a fourth switch connected in series.

7. The conversion circuit an AC / DC conversion circuit connected to the third changeover switch; a DC / AC conversion circuit connected to the second changeover switch and the AC / DC conversion circuit, 6. The charging / discharging device according to claim 5, wherein the controller controls the AC / DC conversion circuit to convert the vehicle power into DC power, and controls the DC / AC conversion circuit to convert the DC power into the power grid power.

8. The charging / discharging device according to claim 5 , wherein the conversion circuit converts three-phase vehicle power to single-phase grid power, or converts single-phase vehicle power to three-phase grid power.

9. 6. The charging / discharging device according to claim 5, wherein after the controller instructs the charging / discharging device to be in a standby state by the operation command, the controller determines whether the electric vehicle is to operate in the charging mode or the reverse flow mode based on a numerical value of the operation command.

10. 10. The charging / discharging device according to claim 9, wherein after the standby state, the controller sets the first current flowing through the charging path according to the current information and turns on the first change-over switch of the charging circuit.

11. 10. The charging / discharging device according to claim 9, wherein after the standby state, the controller sets the second current flowing through the reverse flow path based on the current information, turns on a second transfer switch and a third transfer switch of the reverse flow circuit, and operates the conversion circuit.

12. Plug and a first cable connected to the plug; a second cable connected to the connector; a charging / discharging device connected to the first cable and the second cable, The charging / discharging device is a charging circuit connected to the first cable and the second cable, the charging circuit providing a charging path that supplies grid power from the plug to the connector; a reverse flow circuit connected to the first cable and the second cable, the reverse flow circuit providing a reverse flow path for reverse flow of vehicle power from the connector to the plug, the charging circuit includes a first changeover switch having one end connected to the first cable and the other end connected to the second cable; The reverse flow circuit includes: a second changeover switch having one end connected to the first cable; a conversion circuit having one end connected to the second changeover switch; a third changeover switch having one end connected to the other end of the conversion circuit and the other end connected to the second cable.

13. 13. The electric vehicle charger of claim 12, wherein the charging / discharging device receives specification information of the plug through the first cable, transmits current information and an operation command to and from the electric vehicle through the second cable, and determines whether the electric vehicle is to operate in a charging mode or a reverse flow mode based on the operation command.

14. 14. The electric vehicle charger of claim 13, wherein in the charging mode, the charging / discharging device provides the current information based on the specification information, sets a first current flowing through the charging path, and charges the electric vehicle based on the first current; and in the reverse flow mode, the charging / discharging device provides the current information based on the specification information, sets a second current flowing through the reverse flow path, and performs reverse power flow to the power grid based on the second current.

15. 13. The electric vehicle charger according to claim 12, wherein the charging path is connected in parallel with the reverse flow path, and in a charging mode, a controller of the charging / discharging device turns on the first change-over switch, turns off the second change-over switch and the third change-over switch, and disables the conversion circuit.

16. 13. The electric vehicle charger according to claim 12, wherein the charging path is connected in parallel with the reverse flow path, and in a reverse flow mode, a controller of the charging / discharging device turns off the first change-over switch, turns on the second change-over switch and the third change-over switch, and activates the conversion circuit.

17. 17. The electric vehicle charger of claim 16, wherein the reverse flow path converts three-phase vehicle power to single-phase grid power or converts single-phase vehicle power to three-phase grid power.

18. 15. The electric vehicle charger of claim 14, wherein the plug and the first cable have a modular structure, the first cable and the charging / discharging device are connected in a detachable manner, and the charging / discharging device receives specification information of the plug through the first cable and sets the first current flowing through the charging path or the second current flowing through the reverse flow path based on the specification information.

19. 15. The electric vehicle charger of claim 14, wherein after the operation command instructs the charging / discharging device to enter a standby state, the charging / discharging device determines whether the electric vehicle is to operate in a charging mode or a reverse flow mode based on a numerical value of the operation command.

20. 20. The electric vehicle charger of claim 19, wherein after the standby state, the charging / discharging device sets the first current flowing through the charging path according to the current information and forms the charging path, or after the standby state, the charging / discharging device sets the second current flowing through the reverse flow path according to the current information and forms the reverse flow path.

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