Electric Bicycle Acceleration Control Method
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Solution Overview
Problem
Electric bicycles often experience sudden starts when the throttle is operated, degrading the ride sensation and necessitating a safety measure to prevent such occurrences.
Innovation Solution
A control method and system that compares the user-input acceleration command value with a reference value, adjusting the motor's speed gradient to be gentler and increasing the time for the motor's rotation speed to reach a target speed, thereby preventing sudden starts by varying the speed gradient and time to reach the target speed based on the input acceleration command value.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the throttle is operated to accelerate the electric bicycle, then the motor rotates and the bicycle travels forward, but sudden start occurs degrading ride sensation
Solution Approach 1:
The patent changes the speed gradient parameter dynamically based on the acceleration command value. When the acceleration command value exceeds a reference value, the speed gradient is reduced to be gentler than the target speed gradient, thereby preventing sudden start while still allowing acceleration. This parameter adjustment resolves the contradiction by modifying the speed profile rather than simply limiting acceleration.
2Productivity
If the acceleration command value is increased to improve acceleration performance, then the motor reaches target speed faster, but sudden start occurs
Solution Approach 1:
The patent applies dynamic control by adjusting the speed gradient based on the acceleration command value. The system dynamically determines whether to use the target speed gradient or a gentler speed gradient depending on whether the acceleration command exceeds the reference value. This dynamic adjustment maintains acceleration performance when needed while preventing sudden start when the acceleration command is too high.
Solution Approach 2:
The patent uses feedback control by comparing the acceleration command value with a reference value and adjusting the speed gradient accordingly. The electronic control unit continuously monitors the acceleration command and modifies the motor speed profile based on this comparison, creating a closed-loop control system that prevents sudden start while maintaining acceleration performance.
3Loss of time
If the motor rotation speed increases quickly to reach target speed, then acceleration is improved, but the time taken to reach target speed is too short causing sudden start
Solution Approach 1:
The patent changes the time parameter by increasing the time taken for the motor rotation speed to reach the target speed when the acceleration command value exceeds the reference value. This time extension is achieved by using a gentler speed gradient, which smoothly increases the motor speed over a longer period, thereby preventing sudden start while still achieving the acceleration goal.
Data Source
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AI summary
An electric bicycle and a control method thereof are disclosed. The disclosed control method, which drives the electric bicycle by rotating a motor using electrical energy accumulated in a battery, includes receiving an acceleration command value input by a user to accelerate the electric bicycle upon starting the electric bicycle from a stopped state, comparing the input acceleration command value with a reference value, and increasing a time taken for a rotation speed of the motor to reach a target speed when the input acceleration command value is greater than the reference value.