Hill descent control method

Abstract

This invention relates to a hill descent control method for use in an electric vehicle. The electric vehicle includes a power system, a hill descent control switch, and drive wheels. The power system includes a motor and a motor controller. The motor is equipped with a motor angle sensor that senses changes in the motor angle and provides a motor angle sensing signal. The motor controller is electrically connected to the motor and can receive a throttle opening signal from the electric vehicle and output current to the motor. It can also receive the motor angle sensing signal to obtain the vehicle speed and driving status. The hill descent control switch is electrically connected to the motor controller. When the hill descent control switch is activated, it sends a hill descent control signal to the motor controller. The drive wheels are driven by the motor. This invention achieves hill descent control by controlling the vehicle speed when descending a slope or reversing. The driver only needs to control the direction of travel, without needing to control the throttle and brakes, allowing the driver to focus more intently on controlling the electric vehicle's direction of travel on the slope.

Description

Technical Field

[0001] This invention relates to a method for hill descent control, and more particularly to a method for hill descent control applicable to electric vehicles that are not equipped with electronic stability programs and anti-lock braking systems. Prior Technology

[0002] Vehicles commonly found on the market with hill descent control typically utilize the Electronic Stability Program (ESP) and Anti-lock Braking System (ABS) to perform the hill descent control function. When the driver activates the Hill Descent Control (HDC) function, if the vehicle is on a slope and the speed exceeds a certain limit, the ESP and ABS will apply the brakes, using high-frequency braking to control the speed downhill to below the specified limit. At this time, the driver does not need to press the accelerator or brake, and the hill descent control system can use a specific speed to descend the slope.

[0003] However, the cost of vehicles equipped with electronic stability programs and anti-lock braking systems has increased, and most two-wheeled electric vehicles do not have these features. Driven by this, and in the spirit of proactive invention, the inventor sought a method for hill descent control that could solve these problems, and after numerous research and experiments, finally completed this invention. Summary of the Invention

[0004] The main objective of this invention is to provide a method for hill descent control, enabling electric vehicles to achieve hill descent control without the presence of Electronic Stability Program (ESP) and Anti-lock Braking System (ABS). This method controls the vehicle speed when going downhill or reversing, allowing the driver to control only the direction of travel without additional control of the accelerator and brakes. This allows the driver to have greater focus and concentrate more on controlling the direction of travel of the electric vehicle on the slope.

[0005] To achieve the above objectives, the hill descent control method of the present invention is applied to an electric vehicle, which includes a power system, a hill descent control switch, and a drive wheel. The power system includes a motor and a motor controller. The motor is equipped with a motor angle sensor, which can sense changes in the motor angle and provide a motor angle sensing signal. The motor controller is electrically connected to the motor and can receive a throttle opening signal from the electric vehicle and output current to the motor. It can also receive the motor angle sensing signal to obtain the vehicle speed and driving status. The hill descent control switch is electrically connected to the motor controller. When the hill descent control switch is activated, it sends a hill descent control signal to the motor controller. The drive wheel is driven by the motor.

[0006] The method for gentle descent of a slope includes the following steps: (A) The electric vehicle is in a drivable state and proceeds to step (B); (B) Determine whether the ramp descent switch is on. If yes, proceed to step (C); otherwise, proceed to step (G). (C) Determine whether the electric vehicle is moving forward or backward. If it is moving forward, proceed to step (D1); if it is moving backward, proceed to step (D2). (D1) Determine whether the throttle opening of the electric vehicle is equal to 0% and the speed of the electric vehicle is greater than a specific forward speed. If yes, proceed to step (E); otherwise, proceed to step (F). (D2) Determine whether the throttle opening of the electric vehicle is equal to 0% and whether the speed of the electric vehicle is greater than a specific reverse speed. If yes, proceed to step (E); otherwise, proceed to step (F). (E) The power system applies a resistive force to the drive wheels, performs the ramp descent function, and returns to step (D1) or (D2); (F) The power system does not apply resistance to the drive wheels, suspends the hill descent control function, and returns to step (A); and (G) The power system does not apply the resistive force to the drive wheels, terminates the ramp descent function, and returns to step (A).

[0007] The aforementioned electric vehicle may further include a hill descent control indicator light, electrically connected to a motor controller, such that step (B) further includes the following sub-steps: (B1) Determine whether the ramp descent switch is turned on. If yes, proceed to step (B2); otherwise, proceed to step (B3). (B2) The ramp descent indicator light turns on, and step (C) is executed; and (B3) The ramp descent indicator light is turned off, and step (G) is executed.

[0008] The aforementioned specific forward speed can be 10 kph, and the aforementioned specific reverse speed can be 3 kph.

[0009] The above step (D1) can be further defined as: determining whether the throttle opening of the electric vehicle is equal to 0% and whether the speed of the electric vehicle is greater than a certain forward speed by a hysteresis speed. If so, proceed to step (E); otherwise, proceed to step (F). The above step (D2) can be further defined as: determining whether the throttle opening of the electric vehicle is equal to 0% and whether the speed of the electric vehicle is greater than a certain reverse speed by a hysteresis speed. If so, proceed to step (E); otherwise, proceed to step (F).

[0010] The hysteresis speed mentioned above can be 1 kph.

[0011] The aforementioned motor controller may include six power transistors, which are evenly divided into three upper phase arms and three lower phase arms, which are electrically connected to the motor respectively; the resistance force is increased by the motor controller performing reverse drive on the motor, by short-circuiting the three lower phase arms of the motor controller, or by using the above two methods alternately.

[0012] The above step (E) can be further described as follows: the power system applies a resistive force to the drive wheels to perform the hill descent control function, which may cause the electric vehicle to shake or the hill descent control indicator light to flash, and then return to step (D1) or (D2).

[0013] The motor described above can be connected to the drive wheel via a transmission unit, or the motor can be a hub motor, so that the drive wheel system is directly driven by the motor.

[0014] The above overview and the following detailed description are illustrative in nature and are intended to further illustrate the scope of the invention. Other objects and advantages of the invention will be explained in the subsequent description and illustrations. Simple Explanation of the Diagram

[0015] Figure 1 is a system configuration diagram of an electric vehicle according to the first embodiment of the present invention. Figure 2 is a flowchart of the slope descent method according to the first embodiment of the present invention. Figure 3 is a system configuration diagram of an electric vehicle according to the second embodiment of the present invention. Figure 4 is a flowchart of the slope descent method according to the second embodiment of the present invention. Implementation

[0016] Please refer to Figure 1, which is a system configuration diagram of an electric vehicle according to the first embodiment of the present invention. The figure shows an electric vehicle 1, mainly including a power system 2, a hill descent control switch 3, and a drive wheel 4. The power system 2 includes a motor 21 and a motor controller 22. In this embodiment, the motor 21 is connected to the drive wheel 4 via a transmission unit 6, and the transmission unit 6 is a reduction mechanism with a fixed reduction ratio, which can drive the drive wheel 4 to generate power for the electric vehicle 1. However, this is not a limitation; the motor 21 can also be a hub motor, and the motor controller 22 can directly drive the motor 21 without going through the transmission unit 6. Furthermore, the motor 21 is equipped with a motor angle sensor 211, which can sense changes in the angle of the motor 21 and provide a motor angle sensing signal S1 to the motor controller 22. The motor controller 22 is electrically connected to the motor 21, and can receive a throttle opening signal S2 from the electric vehicle 1 and output current to the motor 21. It can also receive the motor angle sensing signal S1 to obtain the vehicle speed and driving status of the electric vehicle 1. The motor controller 22 contains a microcontroller unit (MCU) that can calculate the time to know the change period of the motor angle sensing signal S1, and calculate the vehicle speed through the relationship between the fixed reduction ratio of the transmission unit 6 and the wheel circumference of the drive wheel 4. It can also determine the steering to confirm whether the electric vehicle 1 is moving forward or backward. When the electric vehicle 1 is moving forward downhill, the angle increment of the motor angle sensor 211 is accumulated during the forward rotation. When the electric vehicle 1 is moving backward downhill, the angle increment of the motor angle sensor 211 is accumulated during the reverse rotation. Alternatively, the driving status of the electric vehicle 1 can be obtained by using a motor angle sensor 211 with a specific signal period arrangement for forward / backward movement. The hill descent control switch 3 is electrically connected to the motor controller 22. When the driver needs to use the hill descent control function, the hill descent control switch 3 can be turned on (for example, the hill descent control switch 3 can be in the form of a button, pressing the button will turn on the hill descent control switch 3). The hill descent control switch 3 will send a hill descent control signal S3 to the motor controller 22. After the condition is determined, the hill descent control function can be executed.

[0017] Please refer to Figure 2, which is a flowchart of the slope descent method according to the first embodiment of the present invention. As shown in the figure, the slope descent method includes the following steps: Step (A) The electric vehicle 1 is in a drivable state and step (B) is executed. Step (B) Determine whether the slope descent switch 3 is turned on. If yes, proceed to step (C); otherwise, proceed to step (G). When the slope descent switch 3 is turned on by the driver, the slope descent control signal S3 is transmitted to the motor controller 22 via a wiring connection. Step (C) Determine whether the electric vehicle 1 is moving forward or backward. If it is moving forward, proceed to step (D1); if it is moving backward, proceed to step (D2). This step is used to determine whether the electric vehicle 1 is moving forward or backward downhill. Step (D1) determines whether the throttle opening of electric vehicle 1 is equal to 0% and whether the speed of electric vehicle is greater than a specific forward speed. If so, proceed to step (E); otherwise, proceed to step (F). This step is used to determine whether the driver has turned the throttle and whether the speed has increased due to the drop. The specific forward speed is 10 kph, and this value is stored as a parameter in motor controller 22. It can also be modified by the instrument, or transmitted wirelessly or via wired connection or by the device. Step (D2) determines whether the throttle opening of electric vehicle 1 is equal to 0% and whether the speed of electric vehicle is greater than a specific reverse speed. If so, proceed to step (E); otherwise, proceed to step (F). This step is used to determine whether the driver has turned the throttle and whether the speed has increased due to the reverse speed. The specific reverse speed is 3 kph, and this value is stored as a parameter in motor controller 22. It can also be modified by the instrument, or transmitted wirelessly or via wired connection or by the device. Step (E): Power system 2 applies an impedance force to drive wheel 4, performs hill descent control, and returns to step (D1) or (D2). The impedance force applied to the drive wheel by power system 3 is used to decelerate the electric vehicle 1 downhill. In this embodiment, motor controller 22 includes six power transistors, which are evenly divided into three upper and three lower phases, electrically connected to motor 21. The impedance force is achieved by motor controller 22 driving motor 21 in the opposite direction, by short-circuiting the three lower phases of motor controller 22 to increase resistance, or by alternating between the two methods. Step (F): Power system 2 stops applying an impedance force to drive wheel 4, suspends hill descent control, and returns to step (A). If the conditions of step (D1) or (D2) are not met, power system 3 will no longer apply an impedance force to drive wheel 4, suspending hill descent control. Step (G) The power system 2 does not apply resistance force to the drive wheels 4, ends the execution of the hill descent control function, and returns to step (A). When the hill descent control switch 3 is turned off by the driver, the hill descent control switch 3 will no longer send the hill descent control signal S3 to the motor controller 22, and end the execution of the hill descent control function.

[0018] As can be seen from the above, when the hill descent control function is activated, the deceleration resistance is continuously adjusted. When the electric vehicle 1's speed on a downhill slope exceeds a specific forward or reverse speed, the deceleration resistance is increased to maintain the vehicle speed within that range. However, if the downhill slope exceeds the designed deceleration capacity of the electric vehicle 1, the maximum deceleration resistance is used to assist in slowing down, giving the driver more reaction time to apply the brakes.

[0019] Step (D1) can be further defined as follows: Determine whether the throttle opening of electric vehicle 1 is 0% and whether the vehicle speed is greater than a specific forward speed by a hysteresis speed. If yes, proceed to step (E); otherwise, proceed to step (F). The hysteresis speed setting adds a limitation to the hysteresis zone to prevent repeated switching between hill descent control and pause when the vehicle speed changes near a specific forward speed. The hysteresis speed can be 1 kph. Step (D2) can be further defined as follows: Determine whether the throttle opening of electric vehicle 1 is 0% and whether the vehicle speed is greater than a specific reverse speed by a hysteresis speed. If yes, proceed to step (E); otherwise, proceed to step (F). The hysteresis speed setting adds a limitation to the hysteresis zone to prevent repeated switching between hill descent control and pause when the vehicle speed changes near a specific reverse speed. The hysteresis speed can be 1 kph.

[0020] Step (E) can be further described as follows: the power system 2 applies a resistive force to the drive wheel 4 to perform the hill descent control function, which causes the electric vehicle 1 to shake or the hill descent control indicator 5 to flash, and then returns to step (D1) or (D2). During the operation of the hill descent control function, the magnitude of the deceleration torque of the electric vehicle 1 can be changed rapidly, causing the electric vehicle 1 to shake and the hill descent control indicator 5 to flash, reminding the driver that the hill descent control function is in operation. The frequency of the change in resistance can also vary depending on the vehicle speed.

[0021] Please refer to Figures 3 and 4, which are respectively a system configuration diagram of the electric vehicle according to the second embodiment of the present invention and a flowchart of the method for hill descent control. Figure 3 shows an electric vehicle 1', whose basic structure is the same as that of the first embodiment, except that the electric vehicle 1' further includes a hill descent control indicator 5, which is electrically connected to the motor controller 22; while Figure 4 shows a method for hill descent control, whose basic process is the same as that of the first embodiment, except that step (B) further includes the following sub-steps: (B1) Determine whether the hill descent control switch 3 is turned on, if so, proceed to step (B2), otherwise proceed to step (B3); (B2) Turn on the hill descent control indicator 5 and proceed to step (C); and (B3) Turn off the hill descent control indicator 5 and proceed to step (G). The hill descent control indicator 5 is typically located on the instrument panel. When the hill descent control function is activated, the motor controller 22 sends a signal to illuminate the indicator 5, alerting the driver that the hill descent control function is in operation. The indicator 5 remains illuminated even when the motor controller 22 pauses the hill descent control function. When the hill descent control function is no longer needed, the driver turns off the hill descent control switch 3. The motor controller 22 then terminates the hill descent control function and turns off the indicator 5, returning the vehicle to normal driving conditions.

[0022] The above embodiments are merely examples for the purpose of illustration. The scope of the claims made in this invention should be determined by the claims of the patent application, and not limited to the above embodiments.

[0023] 1,1': Electric vehicles 2: Power System 21: Motor 211: Motor Angle Sensor 22: Motor Controller 3: Ramp Descent Switch 4: Drive wheels 5: Slope Descent Indicator Light 6: Transmission Unit S1: Motor angle sensing signal S2: Throttle opening signal S3: Slope Descent Control Signal

Claims

1. A method for hill descent control, used in an electric vehicle, the electric vehicle comprising: a power system including a motor and a motor controller, the motor being equipped with a motor angle sensor capable of sensing changes in the motor angle and providing a motor angle sensing signal; the motor controller being electrically connected to the motor, capable of receiving a throttle opening signal from the electric vehicle and outputting current to the motor, and also capable of receiving the motor angle sensing signal to obtain the vehicle speed and driving status; the motor controller including six power transistors, which are evenly divided into three upper phase arms and three lower phase arms, respectively electrically connected to the motor; a hill descent control switch electrically connected to the motor controller, the hill descent control switch emitting a hill descent control signal to the motor controller when activated; and a drive wheel driven by the motor; wherein... The ramp descent method includes the following steps: (A) The electric vehicle is in a drivable state and step (B) is executed; (B) It is determined whether the ramp descent switch is turned on. If yes, step (C) is executed; otherwise, step (G) is executed; (C) It is determined whether the electric vehicle is moving forward or backward. If it is moving forward, step (D1) is executed; if it is moving backward, step (D2) is executed; (D1) It is determined whether the throttle opening of the electric vehicle is equal to 0% and the speed of the electric vehicle is greater than a specific forward speed. If yes, step (E) is executed; otherwise, step (F) is executed; (D2) It is determined whether the throttle opening of the electric vehicle is equal to 0% and the speed of the electric vehicle is greater than a specific reverse speed. If yes, step (E) is executed; otherwise, step (F) is executed. (E) The power system applies an impedance force to the drive wheel to perform the ramp descent function. The impedance force is increased by the motor controller driving the motor in the opposite direction, by short-circuiting the three-phase lower arm of the motor controller, or by alternating between the two methods, and returns to step (D1) or (D2); (F) The power system does not apply the impedance force to the drive wheel, suspends the ramp descent function, and returns to step (A); and (G) The power system does not apply the impedance force to the drive wheel, terminates the ramp descent function, and returns to step (A).

2. The slope descent method as described in claim 1, wherein, The electric vehicle further includes a hill descent control indicator light, which is electrically connected to the motor controller, such that step (B) further includes the following sub-steps: (B1) determining whether the hill descent control switch is turned on; if so, proceed to step (B2); otherwise, proceed to step (B3); (B2) turn on the hill descent control indicator light and proceed to step (C); and (B3) turn off the hill descent control indicator light and proceed to step (G).

3. The slope descent method as described in claim 1, wherein, The specific forward speed is 10 kph, and the specific reverse speed is 3 kph.

4. The slope descent method as described in claim 1, wherein, Step (D1) further involves determining whether the throttle opening of the electric vehicle is equal to 0% and whether the speed of the electric vehicle is greater than the specific forward speed by a hysteresis speed. If so, proceed to step (E); otherwise, proceed to step (F). Step (D2) further involves determining whether the throttle opening of the electric vehicle is equal to 0% and whether the speed of the electric vehicle is greater than the specific reverse speed by a hysteresis speed. If so, proceed to step (E); otherwise, proceed to step (F).

5. The slope descent method as described in claim 4, wherein, The hysteresis speed system is 1 kph.

6. The slope descent method as described in claim 2, wherein, Step (E) is further described as follows: the power system applies an impedance force to the drive wheel to perform the hill descent function. This impedance force is achieved by the motor controller driving the motor in the opposite direction, by short-circuiting the three-phase lower arm of the motor controller to increase resistance, or by alternating between the two methods. This causes the electric vehicle to shake or the hill descent indicator light to flash, and then returns to step (D1) or (D2).

7. The slope descent method as described in claim 1, wherein, The motor is connected to the drive wheel via a transmission unit, or the motor is a hub motor, so that the drive wheel is directly driven by the motor.

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