Steering wheel locking control device and method

Abstract

A steering wheel locking control device and method are provided. The device may include: a power switch for receiving power from a battery when the vehicle ignition switch is off; and a switching unit connected to a motor, which is activated when power is received through the power switch and is used to lock the steering wheel through a closed circuit formed by short-circuiting the motor phases. The device and method provided in this disclosure can prevent the steering wheel from spinning freely when the vehicle ignition switch is off.

Description

Technical Field

[0001] Exemplary embodiments of this disclosure relate to a steering wheel locking control device and method, and more specifically, to a steering wheel locking control device and method capable of preventing the steering wheel from spinning freely when the vehicle ignition switch is turned off. Background Technology

[0002] SBW (Steer-By-Wire) system refers to a steering system that eliminates the mechanical connection between the steering wheel and the vehicle wheels. The SBW system receives the rotation signal from the steering wheel through the ECU (Electronic Control Unit) and, based on the received rotation signal, operates the steering assist motors connected to the wheels to steer the vehicle.

[0003] Because the SBW system eliminates the mechanical connection structure of the existing steering system, the SBW system can increase the degree of freedom of layout according to the configuration of the steering system, improve fuel efficiency, and eliminate interference from the reverse input from the wheels.

[0004] When the ignition switch of a vehicle equipped with an SBW system is off, the ECU cannot operate. Therefore, the steering wheel is not locked and instead spins freely. In this situation, if the driver stands up while holding the steering wheel, they may face a risk of injury.

[0005] Therefore, there is a need to develop technology that can prevent the steering wheel from spinning freely when the vehicle's ignition switch is off.

[0006] The related technology disclosed herein is from Korean Patent No. 10-1987703, published on June 11, 2019, entitled "Steering-by-wire system and control method thereof". Summary of the Invention

[0007] Various embodiments relate to steering wheel locking control devices and methods that can prevent the steering wheel from spinning freely when the vehicle ignition switch is turned off.

[0008] The problems to be solved by this disclosure are not limited to those described above, and those skilled in the art will clearly understand other unmentioned problems through the following description.

[0009] In one embodiment, the steering wheel locking control device may include: a power switch configured to receive power from a battery when the vehicle ignition switch is off; and a switching unit connected to a motor, the switching unit being turned on when receiving power through the power switch and configured to lock the steering wheel through a closed circuit formed by short-circuiting the phases of the motor.

[0010] When the vehicle ignition switch is off, the power switch is turned on in response to a low signal applied thereto, which is set to a default value by a pull-down resistor in the ECU (electronic control unit).

[0011] The power switch can be implemented as an EFT (Electric Field Transistor), which has a gate electrically connected to the MCU (Micro Controller Unit) and a source electrically connected to the battery. The power switch is turned on when a low signal set by the pull-down resistor in the ECU is applied to the gate.

[0012] Based on the operation of the steering wheel, the switching unit can lock the steering wheel by applying a reaction torque to the steering wheel, the reaction torque being caused by the back electromotive force generated by the motor in the closed circuit.

[0013] The switching unit may include one or more switches, each of which is electrically connected to a corresponding phase of the motor.

[0014] The switching unit may include three switches electrically connected to each phase of the motor. Each of the three switches may be implemented as an EFT, having a gate electrically connected to a line of the power switch, a drain electrically connected to the corresponding phase of the motor, and a source grounded. When power is received through the power switch, the three switches open to form the closed circuit.

[0015] The switching unit may include two switches configured to electrically connect a phase of the motor. The two switches may be electrically connected to each other, and when power is received through the power switch, the two switches open to form the closed circuit.

[0016] The steering wheel locking control device may also include a protection circuit unit. When the MCU receives a control signal corresponding to the opening of the vehicle ignition switch, the protection circuit unit is configured to control the switch unit to stop working, so that the power switch does not need to work.

[0017] The protection circuit unit can be implemented as an EFT, which has a gate electrically connected to the MCU, a drain electrically connected to the battery, and a grounded source.

[0018] In one embodiment, the steering wheel locking control method includes: receiving power from a battery via a power switch, the power switch being turned on when the vehicle ignition switch is off; and when power is received via the power switch, a switching unit connected to the motor is turned on, thereby locking the steering wheel through a closed circuit formed by short-circuiting the motor phases.

[0019] When receiving power from the battery, the power switch can be turned on in response to a low signal applied thereto when the vehicle ignition switch is off, the low signal being set to a default value via a pull-down resistor within the ECU.

[0020] During the steering wheel locking process, the switching unit may include three switches electrically connected to each phase of the motor. Each of the three switches is implemented as an EFT, which has a gate electrically connected to a line of the power switch, a drain electrically connected to the corresponding phase of the motor, and a source grounded. When power is received through the power switch, the three switches open to form the closed circuit.

[0021] During the steering wheel locking process, the switching unit may include two switches configured to be electrically connected to a phase of the motor, wherein the two switches are electrically connected to each other, and the two switches are turned on to form the closed circuit when power is received through the power switch.

[0022] The steering wheel locking control method may further include, when the MCU receives a control signal corresponding to the opening of the vehicle ignition switch, controlling the switch unit to stop working through the protection circuit unit, so that the power switch does not need to work.

[0023] According to embodiments of this disclosure, when the vehicle ignition switch is off, the steering wheel locking control device and method can prevent the steering wheel from spinning freely. Therefore, when the driver stands up to grip the steering wheel or strengthens his / her grip on the steering wheel, the steering wheel locking control device and method can prevent the vehicle from turning rapidly, thereby protecting the driver from the risk of injury.

[0024] Compared to systems with mechanical devices applied thereto (e.g., key locking systems), steering wheel locking controls and methods can reduce manufacturing costs.

[0025] The effects of this disclosure are not limited to those described above, but may include a variety of effects derived from the following, provided that such effects are obvious to those skilled in the art. Attached Figure Description

[0026] Figure 1 This is a diagram illustrating a schematic configuration of an SBW (steer-by-wire) system according to an embodiment of the present disclosure;

[0027] Figure 2 This is a diagram illustrating a steering wheel locking control device according to an embodiment of the present disclosure;

[0028] Figure 3 This is a diagram used to describe a switching unit according to an embodiment of the present disclosure;

[0029] Figure 4 This is a diagram used to describe a switching unit according to another embodiment of the present disclosure. Detailed Implementation

[0030] As is customary in the relevant field, some exemplary embodiments may be illustrated in the accompanying drawings as functional blocks, units, and / or modules. Those skilled in the art will understand that these blocks, units, and / or modules are physically implemented by electronic (or optical) circuitry, such as logic circuits, discrete components, processors, hardwired circuits, memory elements, wiring connections, etc. When blocks, units, and / or modules are implemented by processors or similar hardware, they can be programmed and controlled using software (e.g., code) to perform the various functions discussed herein. Alternatively, each block, unit, and / or module may be implemented by dedicated hardware or as a combination of dedicated hardware to perform some functions, and processors (e.g., one or more programmed processors and associated circuitry) to perform other functions. Without departing from the scope of the inventive concept, each block, unit, and / or module of some exemplary embodiments may be physically separated into two or more interactive and discrete blocks, units, and / or modules. Furthermore, without departing from the scope of the inventive concept, blocks, units, and / or modules of some exemplary embodiments may be physically combined into more complex blocks, units, and / or modules.

[0031] In the following description, the steering wheel locking control device and method will be illustrated with reference to the accompanying drawings through various exemplary embodiments. It should be noted that the drawings are not drawn to exact scale, and the thickness of lines or the dimensions of components may be exaggerated for ease of description and clarity only. Furthermore, the terminology used herein is defined in consideration of the functionality of the invention and may be changed according to the habits or intentions of the user or operator. Therefore, the definitions of terminology should be based on the overall disclosure set forth herein.

[0032] The embodiments described in this specification can be implemented, for example, by methods or processes, devices, software programs, data streams, or signals. Although features are discussed only in a single context (e.g., only in a method), the discussed features can be implemented in another type (e.g., apparatus or program). An apparatus can be implemented in suitable hardware, software, or firmware. The method can be implemented in a device such as a processor, which generally refers to a processing device including a computer, microprocessor, integrated circuit, or programmable logic device. The processor also includes a communication device, such as a computer, cellular phone, PDA (Personal Digital Assistant), and another device facilitating information communication between end users.

[0033] Figure 1 This is a diagram illustrating a schematic configuration of an SBW (steer-by-wire) system according to an embodiment of the present disclosure.

[0034] Reference Figure 1 The SBW system according to embodiments of this disclosure may include a steering wheel 11, a steering shaft 12 configured to support the steering wheel 11, a motor 120 mounted on one side of the steering shaft 12 and driven by an ECU (electronic control unit) 130, a sensing unit 110 located on one side of the steering shaft 12, the motor 120 or rack 20, the ECU 130, and one or more actuators 140, each actuator 140 being configured to steer the front wheels 18 of the vehicle according to a control signal from the ECU 130. The motor 120 and actuators 140 may be interconnected via communication such as CAN (Controller Area Network), FlexRay, or Ethernet.

[0035] This SBW system has no mechanical connection between the steering wheel 11 and the rack 20. A motor 120 capable of applying a reaction force to the steering wheel 11 is coupled to a column connected to the steering wheel 11. The rack 20 is coupled to an actuator 140 to control the front wheels 18. The actuator 140 is coupled to a steering motor (not shown) to move the rack 20 to control the front wheels 18.

[0036] The sensing unit 110 may receive sensing information from one or more of the steering angle sensor 13 and the torque sensor 14, or may include both the steering angle sensor 13 and the torque sensor 14. The steering angle sensor 13 may sense changes in the rotation of the steering shaft 12 caused by the driver's operation on the steering wheel 11, and the torque sensor 14 may be mounted on one side of the steering shaft 12 and sense the torque output from the motor 120.

[0037] When the vehicle ignition switch is off, the ECU 130 of the SBW system cannot be driven. Therefore, the steering wheel 11 spins freely. In this situation, the driver may be at risk of injury. Therefore, a device is needed to prevent the steering wheel 11 from spinning freely when the vehicle ignition switch is off.

[0038] Therefore, the ECU 130 may include a steering wheel lock control device 200, which locks the steering wheel 11 by short-circuiting (controlling) the three phases of the electric motor 120 when the vehicle ignition switch is off.

[0039] When the vehicle ignition switch is off, the steering wheel locking control device 200 can lock the steering wheel 11 by applying a reaction torque to the steering wheel 11, the reaction torque being caused by the back electromotive force generated by the motor 120. That is, when the vehicle ignition switch is off, the steering wheel locking control device 200 can prevent the steering wheel 11 from spinning freely. This operation can prevent the vehicle from turning rapidly when the driver stands up to grip the steering wheel or increases his / her grip on the steering wheel 11, thereby protecting the driver from injury.

[0040] This steering wheel locking control device 200 can be implemented as an integrated control device installed in the vehicle or as a part of the ECU 130 module.

[0041] The vehicle’s integrated control device or ECU 130 may include a processor, a storage device such as a memory, and a computer program capable of performing specific functions, and the steering wheel lock control device 200 may be implemented as a software module capable of performing unique functions.

[0042] A detailed description of the steering wheel locking control device 200 will be provided in [reference]. Figure 2 Describe it.

[0043] The ECU 130 controls the operation of the motor 120 and controls the output of the actuator 140 to steer the front wheels 18, thereby steering the vehicle.

[0044] In embodiments of this disclosure, an ECU 130 is installed. However, the ECU 130 can be divided into a first ECU for controlling the motor 120 and a second ECU for controlling the actuator 140. In this case, the first ECU can control the operation of the motor 120, while the second ECU can control the output of the actuator 140, which is configured to steer the front wheels 18 of the vehicle.

[0045] When the driver operates the steering wheel 11, the motor 120 provides the driver with an appropriate steering feel by generating a force in the opposite direction of the steering wheel 11, and current is supplied to the motor 120 to generate an appropriate reaction torque to produce a steering feel.

[0046] The motor 120 may include multiple wirings. Based on sensing information from the sensing unit 110, the motor 120 can rotate to generate a back electromotive force.

[0047] The motor 120 is mounted on one side of the steering shaft 12 and is used to provide the driver with appropriate steering feel by generating a reaction torque according to the control signal applied from the ECU 130 to counteract the steering force applied by the driver to the steering wheel 11.

[0048] This motor 120 may include one or more of a three-phase motor and a five-phase motor. However, the motor 120 is not limited to this, but may include any motor as long as it is capable of providing a reaction force to the steering wheel 11.

[0049] Figure 1 R-EPS (Rack-Electric Power Steering) is shown as an SBW system. However, hydraulic EPS, CEPS (Column EPS), DP-EPS (Dual Pinion EPS), etc., can also be used.

[0050] Figure 2 This is a diagram illustrating a steering wheel locking control device according to an embodiment of the present disclosure. Figure 3 This is a diagram used to describe a switching unit according to an embodiment of the present disclosure, and Figure 4 This is a diagram illustrating a switching unit according to another embodiment of the present disclosure.

[0051] Reference Figure 2 According to an embodiment of the present disclosure, the steering wheel locking control device 200 includes an MCU (microcontroller unit) 132, a power switch 210, a switching unit 220, and a protection circuit unit 230.

[0052] Battery 150 supplies power to electronic control devices installed in the vehicle. Generally, battery 150 can provide 12V to 24V DC (Direct Current) power.

[0053] In this disclosure, the battery 150 can be used as a conventional power source and supply power to the steering wheel lock control device 200 when the vehicle ignition switch is off.

[0054] When the vehicle ignition switch is turned off, the power switch 210 is turned on to receive power from the battery 150.

[0055] When the vehicle ignition switch is off, no power is supplied to the MCU 132, and the power switch 210 can be turned on by a low signal received from the ECU 130, which is set by a pull-down resistor within the ECU 130. The ECU pull-down resistor can be a resistor that is set by default between the MCU 132 and the power switch 210.

[0056] When the vehicle ignition switch is turned on, power can be supplied to the MCU 132, and the power switch 210 can be turned on or off according to the control signal from the MCU 132.

[0057] This power switch 210 can be implemented as various switches, such as PFET (P-channel Field Effect Transistor), NFET (N-channel FET), transistor, and relay. However, in this embodiment, the case where the power switch 210 is implemented as a PFET is described as an example. That is, the power switch 210 can be a PFET, which has a gate electrically connected to the MCU 132 and a source electrically connected to the battery 150.

[0058] When the vehicle ignition switch is turned on, power is supplied to the MCU 132. When power is supplied to the MCU 132, it can output a high-level or low-level control signal to control the power switch 210 to turn on / off. That is, when the vehicle ignition switch is on, the MCU 132 can control the power switch 210 to turn on / off according to driving conditions / fault-safe conditions. Furthermore, when the vehicle ignition switch is off, no power is supplied to the MCU 132. Therefore, the gate driver (not shown) configured to control the operation of the motor 120 is turned off. Consequently, the inverter 134 is turned off, and the motor 120 is uncontrolled. Moreover, since power is supplied to the MCU 132 when the vehicle ignition switch is on, the MCU 132 can control the power switch 210 to turn on / off to control the motor 120 according to the condition (on / off condition or fault-safe condition).

[0059] Switching unit 220 can be connected to motor 120. When power is received via power switch 210, switching unit 220 can be turned on to short-circuit a phase of motor 120. A closed circuit can then be formed to lock steering wheel 11. At this time, switching unit 220 can apply a reaction torque to steering wheel 11 to lock it. The reaction torque is generated by the back electromotive force produced by motor 120 in the closed circuit, based on the operation of steering wheel 11.

[0060] This switching unit 220 may include one or more switches electrically connected to the respective phases of the motor 120.

[0061] For example, such as Figure 3 As shown, the switching unit 220 may include three switches connected in parallel between the inverter 134 and the respective phases of the motor 120, such as a first switch, a second switch, and a third switch. In this case, the switching unit 220 can be implemented as various switches, such as PFETs, NFETs, transistors, and relays. However, in this embodiment, the case where the switching unit 220 is implemented as an NFET will be described as an example. That is, each switch of the switching unit 220 can be implemented as an EFT, having a gate electrically connected to the line of the power switch 210, a drain electrically connected to the corresponding phase of the motor 120, and a source grounded (GND). In this case, each switch of the switching unit 220 can be implemented as an NFET.

[0062] For example, when the switching unit 220 includes a first switch NFET1, a second switch NFET2 and a third switch NFET3, the first switch NFET1 can be electrically connected to phase a of the three-phase motor, the second switch NFET2 can be electrically connected to phase b of the three-phase motor, and the third switch NFET3 can be electrically connected to phase c of the three-phase motor.

[0063] When power is received via power switch 210, the switch unit 220 can be turned on to short-circuit each phase of motor 120 to ground, thereby forming a three-phase closed circuit. Based on the back electromotive force generated by motor 120 according to the operation of steering wheel 11, the three-phase closed circuit can supply current to each phase of motor 120.

[0064] When the motor 120 rotates in a three-phase closed circuit formed by the opening of the switching unit 220 and the operation of the steering wheel 11, the motor 120 generates a back electromotive force (EMF). This back EMF acts as a power source, connected to each wire of the motor 120 and supplying current to each wire. When current is supplied to each wire, the motor 120 generates a reaction torque. The motor 120 can apply this reaction torque to the steering wheel 11. The motor 120 can lock the steering wheel 11 using this reaction torque, preventing it from rotating. The reaction torque for locking the steering wheel 11 can be generated based on the reduction ratio (gear ratio of the column reducer) and the torque generated by the back EMF of the motor 120. For example, the reaction torque for locking the steering wheel 11 can be generated by multiplying the reduction ratio (gear ratio of the column reducer) by the torque generated by the back EMF of the motor 120.

[0065] like Figure 4As shown, the switching unit 220 may include two switches electrically connected to a phase of the motor 120. The two switches (e.g., a first switch and a second switch) can be electrically connected to each other. When power is received through the power switch 210, the two switches can be turned on to form a closed circuit. This switching unit 220 can be implemented as various switches, such as PFETs, NFETs, transistors, and relays.

[0066] For example, when the switching unit 220 includes a first switch and a second switch, the first switch can be electrically connected between phase a and phase b of the three-phase motor 120, and the second switch can be electrically connected between phase b and phase c of the three-phase motor 120. In this way, the first and second switches can be electrically connected to each other.

[0067] When power is received from power switch 210, the first and second switches of switching unit 220 can be turned on and electrically connected to each other, and switching unit 220 can be electrically connected to form a three-phase closed circuit. Based on the back electromotive force generated by motor 120 according to the operation of steering wheel 11, the three-phase closed circuit can supply current to each phase of motor 120.

[0068] When the motor 120 rotates in a three-phase closed circuit formed by the opening of the switching unit 220 and the operation of the steering wheel 11, the motor 120 generates a back electromotive force (EMF). This back EMF acts as a power source, connected to each wire of the motor 120 and supplying current to each wire. When current is supplied to each wire, the motor 120 generates a reaction torque. The motor 120 can apply this reaction torque to the steering wheel 11. The motor 120 can lock the steering wheel 11 using this reaction torque, preventing it from rotating. The reaction torque for locking the steering wheel 11 can be generated based on the reduction ratio (gear ratio of the column reducer) and the torque generated by the back EMF of the motor 120. For example, the reaction torque for locking the steering wheel 11 can be generated by multiplying the reduction ratio (gear ratio of the column reducer) by the torque generated by the back EMF of the motor 120.

[0069] When the MCU 132 receives a control signal indicating that the vehicle ignition switch is on, the protection circuit unit 230 can control the switching unit 220 to not operate, without requiring the operation of the power switch 210. In this case, the protection circuit unit 230 can be implemented as various switches, such as PFETs, NFETs, transistors, and relays. However, in this embodiment, the case where the protection circuit unit 230 is implemented as an NFET will be described as an example.

[0070] The protection circuit unit 230 can be a FET, having a gate electrically connected to the MCU 132, a drain electrically connected to the battery 150, and a source electrically connected to ground. In this case, the protection circuit unit 230 can be implemented as an NFET.

[0071] When the vehicle ignition switch is off, no power is supplied to the MCU 132, thus the MCU 132 is not operated. However, when the vehicle ignition switch is on, power can be supplied to the MCU 132, causing the MCU 132 to output control signals to control the operation of the power switch 210 and the protection circuit unit 230. The control signals may include high and low signals.

[0072] When the MCU 132 outputs a high signal and the vehicle ignition switch is turned on, the power switch 210 is turned off, and the protection circuit unit 230 is turned on. Therefore, the switch unit 220 does not work. That is, when a high signal is received from the MCU 132, the protection circuit unit 230 can be turned on to prevent the steering wheel 11 from locking while the vehicle is in motion.

[0073] Thus, when the vehicle ignition switch is off, the steering wheel locking control device and method according to embodiments of the present disclosure can prevent the steering wheel from spinning freely. Therefore, when the driver stands up to grip the steering wheel or strengthens his / her grip on the steering wheel, the steering wheel locking control device and method can prevent the vehicle from turning rapidly, thereby protecting the driver from the risk of injury.

[0074] Compared to systems that utilize mechanical devices (e.g., key locking systems), the steering wheel locking control device and method according to embodiments of this disclosure can reduce manufacturing costs.

[0075] Although exemplary embodiments of this disclosure have been disclosed for illustrative purposes, those skilled in the art will understand that various modifications, additions, and substitutions are possible without departing from the scope and spirit of this disclosure as defined in the appended claims. Therefore, the true technical scope of this disclosure should be defined by the appended claims.

Claims

1. A steering wheel locking control device, comprising: The power switch is configured to receive power from the battery when the vehicle ignition switch is off. A switching unit, connected to the motor, is activated when it receives power through the power switch and is configured to lock the steering wheel via a closed circuit formed by short-circuiting the phases of the motor. as well as When the microcontroller unit (MCU) receives a control signal corresponding to the opening of the vehicle ignition switch, the protection circuit unit is configured to control the switch unit to stop working, so that the power switch does not need to be operated.

2. The steering wheel lock control device according to claim 1, wherein When the vehicle ignition switch is off, the power switch turns on in response to a low signal applied thereto, which is set to a default value by a pull-down resistor in the electronic control unit (ECU).

3. The steering wheel lock control device according to claim 2, wherein The power switch is implemented as an electric field transistor (EFT), which has a gate electrically connected to the MCU and a source electrically connected to the battery. The power switch is turned on when a low signal set by the pull-down resistor in the ECU is applied to the gate.

4. The steering wheel lock control device according to claim 1, wherein Based on the operation of the steering wheel, the switching unit locks the steering wheel by applying a reaction torque to the steering wheel, the reaction torque being caused by the back electromotive force generated by the motor in the closed circuit.

5. The steering wheel lock control device according to claim 1, wherein The switching unit includes one or more switches, each of which is electrically connected to a corresponding phase of the motor.

6. The steering wheel lock control device according to claim 5, wherein The switching unit includes three switches, which are electrically connected to each phase of the motor. The three switches are all implemented as EFTs. ​​Each EFT has a gate electrically connected to the power switch, a drain electrically connected to the corresponding phase of the motor, and a grounded source. When power is received through the power switch, the three switches are turned on to form the closed circuit.

7. The steering wheel locking control device according to claim 5, wherein, The switching unit includes two switches configured to electrically connect a phase of the motor. The two switches are electrically connected to each other, and when power is received through the power switch, the two switches are turned on to form the closed circuit.

8. The steering wheel locking control device according to claim 1, wherein, The protection circuit unit is implemented as an EFT, which has a gate electrically connected to the MCU, a drain electrically connected to the battery, and a source grounded.

9. A steering wheel locking control method, comprising: Power is received from the battery via a power switch that is turned on when the vehicle ignition switch is off. When power is received through the power switch, the switching unit connected to the motor is turned on, thereby locking the steering wheel through a closed circuit formed by short-circuiting the phases of the motor; as well as When the microcontroller unit (MCU) receives the control signal corresponding to turning on the vehicle ignition switch, the protection circuit unit controls the switch unit to stop working, eliminating the need for the power switch to operate.

10. The steering wheel locking control method according to claim 9, wherein, When receiving power from the battery When the vehicle ignition switch is off, the power switch turns on in response to a low signal applied thereto, which is set to a default value by a pull-down resistor in the electronic control unit (ECU).

11. The steering wheel locking control method according to claim 9, wherein, During the steering wheel locking process, According to the operation of the steering wheel, the switching unit locks the steering wheel by applying a reaction torque to the steering wheel, the reaction torque being caused by the back electromotive force generated by the motor in the closed circuit.

12. The steering wheel locking control method according to claim 9, wherein, During the steering wheel locking process, The switching unit includes three switches electrically connected to each phase of the motor. Each of the three switches is implemented as an electric field transistor (EFT). The EFT has a gate electrically connected to the power switch, a drain electrically connected to the corresponding phase of the motor, and a grounded source. When power is received through the power switch, the three switches are turned on to form the closed circuit.

13. The steering wheel locking control method according to claim 9, wherein, During the steering wheel locking process, The switching unit includes two switches configured to be electrically connected to a phase of the motor, wherein the two switches are electrically connected to each other, and the two switches are turned on to form the closed circuit when power is received through the power switch.

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