Method and device for calculating vehicle speed by vehicle controller

Abstract

The invention discloses a method and device for calculating a vehicle speed by a vehicle controller, and the method comprises the following steps: detecting whether a current vehicle has a gearbox ornot if detecting that a motor rotating speed message is offline; assigning the motor rotating speed as a first preset value if the current vehicle does not have the gearbox, and calculating the vehicle speed according to the first preset value; detecting whether a gearbox output shaft rotating speed message is offline or not if the current vehicle has the gearbox; and assigning the gearbox outputshaft rotating speed as a second preset value if it is detected that the gearbox output shaft rotating speed message is offline, and calculating the vehicle speed according to the second preset value.Based on the method and device, when the motor rotating speed message is detected to be offline or the gearbox output shaft rotating speed message is detected to be offline, the motor rotating speedor the gearbox output shaft rotating speed are assigned, so the situation that the vehicle speed calculated by the vehicle controller is 0 is avoided; the situation that the vehicle is at a high vehicle speed and emergency braking occurs can be further avoided, and driving safety is guaranteed.

Description

technical field [0001] The present application relates to the technical field of new energy vehicles, and more specifically, relates to a method and a device for calculating vehicle speed by a vehicle controller. Background technique [0002] EPB (Electrical Park Brake, Electronic Parking Brake) system has several functions of conventional parking, intelligent parking and emergency auxiliary parking, and it is more and more widely used in new energy vehicles. When the new energy vehicle is running, if the driver does not trigger the parking button or the parking switch on the vehicle, the vehicle controller calculates the vehicle speed according to the vehicle motor speed or the transmission output shaft speed, and calculates the vehicle speed Provided to the EPB system, if the EPB system determines that the vehicle speed is lower than a certain threshold, it will activate the intelligent parking function to realize parking. [0003] However, the power system of new energy ...

AI Technical Summary

Problems solved by technology

[0003] However, the power system of new energy vehicles is due to electric current The beating in a very short time and the fast movement of high-power semiconductor switches will emit strong radiation and electromagnetic interference

In this case, the motor speed message may be disconnected, or the gearbox output shaft speed message may be dropped, and when the vehicle controller cannot obtain the motor speed message, or the gearbox output shaft speed message cannot be obtained, The calculated vehicle speed is 0, and the information that the vehicle speed is 0 is provided to the EPB system. After receiving the information that the vehicle speed is 0, the EPB system will start the intelligent parking function to realize parking, and the vehicle actually has At a higher speed, the EPB system activates the smart parking function to park the vehicle, which will cause the vehicle to brake suddenly and endanger driving safety.

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