KR102087701B1 - Power relay assembly driving apparatus and method for electric vehicle - Google Patents

Abstract

The present invention discloses a method and apparatus for driving a power relay assembly for an electric vehicle. The present invention provides a precharge switching unit and a first switching unit and a second switching unit connected in series with each other in parallel with a relay switch, wherein the first switching unit and the second switching unit include a semiconductor switching element and a diode therein. As a result, not only when the power is supplied from the battery to the load side, but also when charging is performed by supplying a charging current to the battery, power can be supplied or cut off while preventing sparking and arcing at the relay.

Description

Power relay assembly driving apparatus and method for electric vehicle

The present invention relates to a method and apparatus for driving a power relay assembly (PRA), and more particularly, to a method and apparatus for driving a power relay assembly for an electric vehicle.

In general, a power relay assembly (PRA) is a power disconnect device that connects and disconnects power from a battery to a motor through a power control unit (PCU) in an electric vehicle and a hybrid vehicle. It is a core component that plays the role of a main gate.

In addition, the power relay assembly (PRA) plays a very important safety role in electric / hybrid vehicles by acting as a safety device that completely cuts off power in the event of system failure or maintenance.

These power relay assemblies provide high voltage relays such as pre-charging relays (450V, 10A and above) and main relays (450V, 100 ~ 150A and above) and wiring connections to the battery / inverter. It consists of components such as high voltage / high current busbars and terminals.

Dual core components are high voltage relays that connect and disconnect high voltage / high current. As such a high voltage relay, a mechanical relay structure in which a special gas (Gas), for example, H2 gas is injected and sealed is adopted to prevent sparks that may occur at the contacts of the relay.

However, since the high voltage relay is heavy due to a special gas, it increases the total weight of the power relay assembly. As a result, there is a problem that the fuel economy of the vehicle is lowered.

In addition, the high voltage relay not only has a complicated mechanical structure, but also the material cost of the component is high, so that the price of the component is high. As a result, there is a problem that the cost of the power relay assembly is increased.

In addition, a power relay assembly including the high voltage relay requires an increase in wiring due to the addition of peripheral devices. As a result, there is a problem that the wiring arrangement becomes complicated.

As an example of the prior art for solving these problems, as shown in FIG. 1, a smart PRA using a semiconductor switching device has been proposed. Korean Patent No. 10-0559398 shown in FIG. 1 (name of the invention: the power connection control device for a hybrid and fuel cell vehicle) turns on the second main relay 7 connecting the-terminal of the battery and the inverter to each other at the initial start-up. Then, before the first main relay 5 is connected, the power semiconductor 6 is pulse width modulated (PWM) controlled so that the current flows intermittently, and the capacitor 8b is charged in advance, so that the first main relay 5 After the equipotential is formed to have the same voltage at both ends, the first main relay 5 is connected to prevent sparks from occurring at both ends of the first main relay 5 when the first main relay 5 is connected.

In addition, when the power supply is cut off, only the first main relay 5 is first turned off in a state where the first main relay 5, the power semiconductor 6, and the second main relay 7 are simultaneously turned on. Off). At this time, since the current flowing through the first main relay 5 continues to flow through the power semiconductor 6, the first main relay 5 does not generate sparks at the contacts, thereby safely shutting off the power supply.

However, in the prior art, although the general power supply can be cut off while power is supplied from the high voltage battery of the electric vehicle to the load (inverter), the operation of cutting off the power when charging the high voltage battery is not possible, and thus, a power relay for an electric vehicle having a new structure. An assembly drive device is required.

The problem to be solved by the present invention is not only when the high voltage battery of the electric vehicle is discharged to supply power to the load, but also when the charging current is supplied to the high voltage battery, it is possible to perform the power supply and shutdown while preventing the occurrence of sparks of the relay. The present invention provides an apparatus and a method for driving a power relay assembly for an electric vehicle.

An apparatus for driving a power relay assembly for an electric vehicle according to a preferred embodiment of the present invention for solving the above problems includes a first relay connected between a negative terminal of a battery and a negative terminal of a load side; A second relay connected between the positive terminal of the battery and the positive terminal of the load side; A first switching part connected to one end of the second relay on a positive terminal side of the battery and the other end connected to a second switching part; One end of which is connected to the first switching unit, and the other end of which is connected to the load-side end of the second relay; A precharge switching unit having one end connected to one end of the second relay on the positive terminal side of the battery and the other end connected to a protection resistor; A protection resistor connected between the precharge switching unit and a connection node of the first switching unit and the second switching unit; And a controller for outputting a control signal to control on / off of the first relay, the second relay, the first switching unit, the second switching unit, and the precharge switching unit.

The first switching unit and the second switching unit may each include: a switching element turned on / off according to a control signal input from the control unit; And a diode connected in parallel with the switching element.

In addition, the diodes included in each of the first switching unit and the second switching unit may have opposite directions.

In addition, the diode of the first switching unit may be set such that the positive terminal side direction of the battery is forward, and the diode of the second switching unit may be set such that the positive terminal side direction of the load side is forward.

In addition, the switching elements included in the first switching unit and the second switching unit may be implemented by an Insulated Gate Bipolar Transistor (IGBT) or a Field Effect Transistor (FET), and include the first switching unit and the second switching unit. The included diode may be implemented as an internal diode contained inside the IGBT or FET.

In addition, when supplying power from the battery to the load side, the controller turns on the first relay and turns on the precharge switching unit so that the current output from the battery is converted into the precharge switching unit; When precharge is performed by flowing to the load side through the diode of the second switching unit, and if an equipotential is formed between both ends of the second relay, the second relay may be turned on and the precharge switching unit may be turned off.

The controller may turn on a switching element included in the first switching unit when the power supply from the battery is cut off to the load side, so that the current output from the battery is changed to the second relay and the first switching unit. After flowing to the load side through the switching element of the first switching unit and the diode of the second switching unit, the second relay may be turned off, and then the power supply may be cut off by turning off the switching element included in the first switching unit. .

When the charging current is supplied to the battery, the controller turns on the switching element of the second switching unit to the battery through the switching element of the second switching unit and the diode of the first switching unit. After the charging current flows to form an equipotential between both ends of the second relay, the second relay is turned on to allow the charging current to flow through the second relay, and then the switching element of the second switching unit is turned off. Normal charging can be performed by turning OFF.

When the charging current is cut off, the controller turns on the switching element of the second switching unit to charge the current through the battery through the switching element of the second switching unit and the diode of the first switching unit. After the flow, the second relay is turned off (OFF) to cut off the charging current flowing through the second relay, and then by switching off the switching element of the second switching unit can be cut off the charging power supply. .

In addition, the power relay assembly driving apparatus for an electric vehicle according to a preferred embodiment of the present invention is installed between the positive terminal of the battery and one end of the second relay, the current output from the battery and the current flowing into the battery. The electronic device may further include a current sensor configured to measure at least one of the measured output signals to the controller, and the controller may output a control signal according to a current value input from the current sensor.

On the other hand, in order to solve the above-mentioned problems, a method for driving a power relay assembly for an electric vehicle according to a preferred embodiment of the present invention, the first relay connected between the negative terminal of the battery and the negative terminal of the load, A second relay connected between a first node connected and a third node connected to a load side positive terminal, a first switching unit connected between the first node and a second node, a connection between the second node and the third node A second switching unit, a precharge switching unit and a protection resistor connected in series between the first node and the second node, the first switching unit and the second switching unit in parallel with the switching element and the switching element. A method of driving a power relay assembly for an electric vehicle including a diode connected to each other, wherein the power is supplied from the battery to the load side. In the step of turning on the first relay; Performing a precharge by turning on the precharge switching unit so that a current output from the battery flows to the load side through a diode of the precharge switching unit and the second switching unit; And when the equipotential is formed between both ends of the second relay, turning on the second relay and turning off the precharge switching unit.

In addition, the electric vehicle power relay assembly driving method according to an embodiment of the present invention, when the power supply from the battery to the load side is cut off, by turning on the switching element included in the first switching unit, Allowing the current outputted from to flow to the load side through the second relay and the switching element of the first switching unit and the diode of the second switching unit; Turning off the second relay; And shutting off the power supply by turning off the switching element included in the first switching unit.

In addition, in the method for driving a power relay assembly for an electric vehicle according to a preferred embodiment of the present invention, when the charging current is supplied to the battery, the switching element of the second switching unit is turned on to switch the second switching unit. Forming an equipotential between both ends of the second relay by allowing a charging current to flow through the device and the diode of the first switching unit; Turning on the second relay to allow a charging current to flow through the second relay; And performing the normal charging by turning off the switching element of the second switching unit.

In addition, the method for driving a power relay assembly for an electric vehicle according to a preferred embodiment of the present invention, when switching off the charging current, by turning on (ON) the switching element of the second switching unit, the switching element of the second switching unit and Allowing a charging current to flow into the battery through the diode of the first switching unit; Turning off the second relay to block charging current flowing through the second relay; And turning off the switching element of the second switching unit to cut off the charging power supply.

The present invention provides a precharge switching unit and a first switching unit and a second switching unit connected in series with each other in parallel with a relay switch, wherein the first switching unit and the second switching unit include a semiconductor switching element and a diode therein. As a result, not only when the power is supplied from the battery to the load side, but also when charging is performed by supplying a charging current to the battery, power can be supplied or cut off while preventing sparking and arcing at the relay.

1 is a diagram illustrating an example of a smart PRA according to the prior art.
2 is a diagram showing the configuration of a PRA driving apparatus for an electric vehicle according to a preferred embodiment of the present invention.
3A to 3E are diagrams illustrating an operation process in which power is supplied from a battery to a load side according to a preferred embodiment of the present invention.
4A to 4C are diagrams illustrating an operation process of supplying a charging current to a battery according to a preferred embodiment of the present invention.

Hereinafter, exemplary embodiments of the present invention will be described with reference to the accompanying drawings.

2 is a diagram showing the configuration of a PRA driving apparatus for an electric vehicle according to a preferred embodiment of the present invention.

Referring to FIG. 2, a PRA driving apparatus (hereinafter, referred to as “driving apparatus”) for an electric vehicle according to a preferred embodiment of the present invention may include a first relay 210, a second relay 220, and a first switching unit ( 110, the second switching unit 120, the precharge switching unit 130, the current sensor 400, the protection resistor 140 and the control unit 300 is configured. Hereinafter, the operation of each component will be described.

The first relay 210 is connected between the negative terminal of the battery 500 and the negative terminal of the load side 600, and supplies power to the load side 600 and charges the battery 500 according to a control signal of the controller 300. The battery is first turned on to electrically connect the negative terminal of the battery 500 and the load side 600 terminal, and at the end of the power supply interruption and the charging interruption, the battery is turned off. 500-the terminal and the load side 600-the terminal is electrically disconnected.

The second relay 220 is connected between the + terminal of the battery 500 and the load side 600 + terminal, and is turned on according to a control signal of the controller 300 to supply regular power to the load side 600. The charging current is supplied from the charging device (not shown) connected to the load side 600 to the battery 500 side.

The first switching unit 110 and the second switching unit 120 are connected in series with each other, and the first switching unit 110 and the second switching unit 120 connected in series with each other are both ends of the second relay 220. Are connected in parallel.

One end of the first switching unit 110 is connected to one end of the second terminal 220 of the positive terminal side of the battery 500, and the other end of the first switching unit 110 is one end of the second switching unit 120. It is connected to and controls the flow of current in accordance with the control signal of the controller 300.

One end of the second switching unit 120 is connected to the other end of the first switching unit 110, and the other end is connected to one end of the load side 600 of the second relay 220 according to the control signal of the controller 300. Control the flow of current.

The first switching unit 110 and the second switching unit 120 are ON / OFF switching elements 111 and 121 and diodes 113 and 123 connected in parallel with the control signal of the control unit 300, respectively. Is implemented. The switching elements 111 and 121 may be implemented as semiconductor switching elements, and the diodes 113 and 123 connected in parallel with the semiconductor switching elements may have a semiconductor switching element (for example, a direction opposite to a current flowing when the semiconductor switching elements 111 and 121 turn on). 111 and 121 are connected in parallel.

Specifically, in the preferred embodiment of the present invention, the switching elements 111 and 121 may be implemented as an Insulated Gate Bipolar Transistor (IGBT) or a Field Effect Transistor (FET), and the diodes 113 and 123 connected in parallel to the switching elements 111 and 121. May be implemented as a separate diode or may be implemented as a diode inside the semiconductor switching device.

When the diodes 113 and 123 included in the first switching unit 110 and the second switching unit 120 are implemented as internal diodes, when the switching elements 111 and 121 are IGBTs, internal diodes formed between the emitter and the collector may be used. In the case where the switching elements 111 and 121 are FETs, the switching elements 111 and 121 may be implemented as internal diodes formed between the source and the drain.

At this time, the diode 113 of the first switching unit 110 and the diode 123 of the second switching unit 120 are set in opposite directions to each other, and the diode 113 of the first switching unit 110 is made of The positive terminal side of the battery 500 is installed from the second switching unit 120 in the forward direction, and the diode 123 of the second switching unit 120 is connected to the positive side of the load side 600 from the first switching unit 110. The terminal side is installed in the forward direction.

One end of the precharge switching unit 130 is connected to one end of the positive terminal side second relay 220 of the battery 500, and the other end thereof is connected to the protection resistor 140. That is, one end of the precharge switching unit 130 is connected to the first node N1, and the second relay 220, the first switching unit 110, and the precharge switching unit 130 are connected to the first node N1. ) Is connected. In addition, like the first switching unit 110 and the second switching unit 120, the precharge switching unit 130 also turns on / off the semiconductor switching device according to a control signal of the control unit 300 ( Hereinafter), and a diode 133 connected in parallel therewith, the precharge switching element 131 is implemented as an IGBT or an FET. The diode 133 may also be implemented as a separate diode, or may be implemented as a diode inside the precharge switching element 131. In addition, the forward direction of the diode 133 of the precharge switching unit 130 is set opposite to the forward direction of the diode 123 of the second switching unit 120.

The protection resistor 140 is connected between the precharge switching unit 130 and the connection node N2 of the first switching unit 110 and the second switching unit 120 to abruptly through the precharge switching unit 130. Prevents current from flowing

The current sensor 400 is installed at the positive terminal side of the battery 500 to measure the current output from the battery 500 or the charging current input to the battery 500 to output to the controller 300.

The control unit 300 receives the current value from the current sensor 400 and irradiates the current value, and accordingly, the switching elements of the first relay 210, the second relay 220, and the first switching unit 110 (hereinafter, referred to as “the 1) switching on / off of the 111, the switching element of the second switching unit 120 (hereinafter referred to as "second switching element") 121 and the precharge switching element 131 The control signal is output to each component.

Meanwhile, the PRA driving apparatus for an electric vehicle according to the preferred embodiment of the present invention illustrated in FIG. 2 may be briefly expressed as follows by defining a connection point between each component as a node.

The first relay 210 is connected between the negative terminal of the battery 500 and the negative terminal of the load side 600, the second relay 220 is the first node (N1) connected to the positive terminal of the battery 500 ) And the load terminal 600 positive terminal is connected between the connected third node (N3).

The first switching unit 110 is connected between the first node N1 and the second node N2, and the second switching unit 120 is connected between the second node N2 and the third node N3. do. The precharge switching unit 130 and the protection resistor 140 are connected in series with each other between the first node N1 and the second node N2.

In addition, when the precharge switching element 131 and the first switching element 111 are implemented with IGBTs (N type FETs), the collectors (drains) of the switching elements 131 and 111 are connected to the first node N1. The emitter (source) is connected to the second node N2. Similarly, when the second switching element 121 is implemented with an IGBT (N type FET), the collector (drain) is connected to the third node N3, and the emitter (source) is connected to the second node N2. Connected.

Hereinafter, with reference to Figures 3a to 4c, the function of each component of the power relay assembly driving apparatus for an electric vehicle according to a preferred embodiment of the present invention, and the power relay assembly driving method for an electric vehicle will be described.

3A to 3E are diagrams illustrating an operation process in which power is supplied from the battery 500 to the load side 600 according to an exemplary embodiment of the present invention. Hereinafter, referring to FIGS. 3A to 3E, an operation process in which power is supplied to and disconnected from the battery 500 from the battery 500 according to an exemplary embodiment of the present invention will be described.

First, in a state in which all switching elements are open, when the power supply is started from the battery 500 to the load side 600, the controller 300 turns on the first relay 210. Then, the precharge switching element 131 is turned on. Then, the current output from the battery 500 flows to the load side 600 through the precharge switching element 131, the protection resistor 140, and the diode 123 of the second switching unit 120, and the load side 600. Pre-charge the capacitor included in (see Fig. 3a).

After the precharge is completed, the controller 300 turns on the second relay 220, and most of the current flowing through the precharge switching element 131 flows through the second relay 220. 3B) When the precharge is completed, an equipotential is formed between both ends of the second relay 220 so that spark or arc does not occur at the contact point of the second relay 220 even when the second relay 220 is turned on. do.

When a current flows through the second relay 220, the control unit 300 turns off the precharge switching element 131 (see FIG. 3C). In this case, the battery 500 is moved from the battery 500 to the load side 600. Normal current supply is made.

After that, when the power supply is cut off from the battery 500 to the load side 600, the control unit 300 turns on the first switching element 111, and the second relay 220 from the battery 500. A portion of the current supplied to the load side 600 through) flows to the load side 600 through the diode 123 of the first switching element 111 and the second switching unit 120 (see FIG. 3D).

In the next step, the control unit 300 turns off the second relay 220, and the current flowing from the battery 500 to the load side 600 now flows only through the first switching element 111 (FIG. 3E). Reference). In a state where current flows through the second relay 220 and the first switching element 111 together, both ends of the second relay 220 form an equipotential, and thus the second relay 220 is turned off. Even in this case, no spark or arc occurs at the contact of the second relay 220.

4A to 4C are diagrams illustrating an operation process of supplying a charging current to the battery 500 according to an exemplary embodiment of the present invention. 4A to 4C, an operation process of supplying and blocking a charging current to the battery 500 according to an exemplary embodiment of the present invention will be described.

First, in a state in which all switching elements are open, when starting charging current supply to the battery 500 side, the controller 300 turns on the first relay 210 and the second switching element 121. Turn ON. Then, the charging current flows to the battery 500 side through the second switching element 121 and the diode 113 of the first switching unit 110 (see current ①), and then turns on the second relay 220. When turned on, a part of the charging current flowing through the second switching element 121 flows to the battery 500 side through the second relay 220 (see current ②), and the controller 300 controls the second switching element ( By turning OFF 121, the charging current flows only through the second relay 220 so that a normal charging process is performed (see FIG. 4A).

In the process of terminating the charging by blocking the charging current, the controller 300 turns on the second switching element 121, and then the control current of the charging current supplied to the battery 500 through the second relay 220. A part flows to the battery 500 through the second switching element 121 and the diode 113 of the first switching unit 110 (see FIG. 4B).

After that, the controller 300 turns off the second relay 220, and the current flowing to the battery 500 now flows only through the second switching element 121 (see FIG. 4C). In a state in which current flows through the second relay 220 and the second switching element 121 together, both ends of the second relay 220 form an equipotential, so that the second relay 220 is turned off. Even in this case, no spark or arc occurs at the contact of the second relay 220.

Finally, when the controller 300 turns off the second switching element 121, the charging current flowing to the battery 500 is completely blocked, and the charging process of the battery 500 is terminated.

So far I looked at the center of the preferred embodiment for the present invention. Those skilled in the art will appreciate that the present invention can be implemented in a modified form without departing from the essential features of the present invention. Therefore, the disclosed embodiments should be considered in descriptive sense only and not for purposes of limitation. The scope of the present invention is shown in the appended claims rather than the foregoing description, and all differences within the scope will be construed as being included in the present invention.

110: first switching unit
111: first switching element 113: diode
120: second switching unit
121: second switching element 123: diode
130: precharge switching unit
131: precharge switching element 133: diode
140: protection resistance
210: first relay 220: second relay
300: control unit
400: current sensor
500: battery
600: load side

Claims (14)

delete A first relay connected between the negative terminal of the battery and the negative terminal of the load side;
A second relay connected between the positive terminal of the battery and the positive terminal of the load side;
A first switching part connected to one end of the second relay on a positive terminal side of the battery and connected to a second switching part on the other end of the battery;
One end of which is connected to the first switching unit and the other end of which is connected to the load side end of the second relay;
A precharge switching unit having one end connected to one end of the second relay on the positive terminal side of the battery and the other end connected to a protection resistor;
A protection resistor connected between the precharge switching unit and a connection node of the first switching unit and the second switching unit; And
A control unit for outputting a control signal to control on / off of the first relay, the second relay, the first switching unit, the second switching unit, and the precharge switching unit,
Each of the first switching unit and the second switching unit
A switching element turned on / off according to a control signal input from the controller; And
A diode connected in parallel with the switching element,
The control unit
When charging current is supplied to the battery
After the switching element of the second switching unit is turned on, charging current flows to the battery through the switching element of the second switching unit and the diode of the first switching unit to form an equipotential between both ends of the second relay. And turning on the second relay to allow a charging current to flow through the second relay, and then normal charging is performed by turning off the switching element of the second switching unit. Relay assembly drive device. The method of claim 2,
The diodes included in the first switching unit and the second switching unit, respectively, the forward direction of the electric vehicle power relay assembly driving apparatus, characterized in that the opposite. The method of claim 3, wherein
The diode of the first switching unit is set such that the positive terminal side direction of the battery is forward, and the diode of the second switching unit is set such that the positive terminal side direction of the load side is forward. Relay assembly drive device. The method of claim 3, wherein
Switching elements included in the first switching unit and the second switching unit
Implemented as an Insulated Gate Bipolar Transistor (IGBT) or Field Effect Transistor (FET),
Diodes included in the first switching unit and the second switching unit
The power relay assembly driving apparatus for an electric vehicle, characterized in that implemented by the internal diode contained in the IGBT or FET. The method according to any one of claims 2 to 5, wherein the control unit
When power is supplied from the battery to the load side,
Turn on the first relay,
Pre-charging by turning on the precharge switching unit so that the current output from the battery flows to the load side through the diodes of the precharge switching unit and the second switching unit,
When the equipotential is formed between both ends of the second relay, the power relay assembly driving apparatus for an electric vehicle, characterized in that the second relay is turned on and the precharge switching unit is turned off. The method of claim 6, wherein the control unit
When the power supply from the battery to the load side is cut off,
After switching on the switching element included in the first switching unit, the current output from the battery flows to the load side through the second relay, the switching element of the first switching unit and the diode of the second switching unit, And turning off the second relay and then turning off the switching element included in the first switching unit to cut off the power supply. delete The method of claim 2, wherein the control unit
If you cut off the charging current supply,
After switching on the switching element of the second switching unit to allow charging current to flow through the switching element of the second switching unit and the diode of the first switching unit, the second relay is turned off. And cut off the charging current flowing through the second relay, and then turn off the switching element of the second switching unit to cut off the charging power supply. The method according to any one of claims 2 to 5,
A current sensor installed between the positive terminal of the battery and one end of the second relay and measuring at least one of a current output from the battery and a current flowing into the battery and outputting the measured value to the controller;
And the control unit outputs a control signal according to the current value input from the current sensor.
A first relay connected between the negative terminal of the battery and the negative terminal of the load side, a second relay connected between the first node connected with the positive terminal of the battery and a third node connected with the positive terminal of the load side, and the first node A first switching unit connected between a second node, a second switching unit connected between the second node and the third node, a precharge switching unit connected in series between the first node and the second node, and a protection A method of driving a power relay assembly for an electric vehicle including a resistor, wherein the first switching unit and the second switching unit include a switching element and a diode connected in parallel with each other.
When charging current is supplied to the battery
Turning on the switching element of the second switching unit to allow charging current to flow through the switching element of the second switching unit and the diode of the first switching unit to form an equipotential between both ends of the second relay; ;
Turning on the second relay to allow a charging current to flow through the second relay; And
And driving the regular charging by turning off the switching element of the second switching unit. The method of claim 11,
When power is supplied from the battery to the load side,
Turning on the first relay;
Performing a precharge by turning on the precharge switching unit so that a current output from the battery flows to the load side through a diode of the precharge switching unit and the second switching unit; And
And when the equipotential is formed between both ends of the second relay, turning on the second relay and turning off the precharge switching unit. The method of claim 12,
When the power supply from the battery to the load side is cut off,
Turning on the switching element included in the first switching unit so that a current output from the battery flows to the load side through the second relay and the switching element of the first switching unit and the diode of the second switching unit;
Turning off the second relay; And
And turning off the switching element included in the first switching unit to cut off the power supply. The method of claim 11,
If you cut off the charging current supply,
Turning on the switching element of the second switching unit so that charging current flows to the battery through the switching element of the second switching unit and the diode of the first switching unit;
Turning off the second relay to block charging current flowing through the second relay; And
And turning off the switching element of the second switching unit (OFF) to cut off the charging power supply.

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