Motor Driving Control Apparatus for Electric Bicycles
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Solution Overview
Problem
Existing electrically assisted bicycle systems face challenges in providing sufficient assistance when starting from a stop and in tracking torque requests with varying cycles, leading to inefficient assistance and potential loss in electric efficiency.
Innovation Solution
A motor driving control apparatus that includes a smoothing processing unit to calculate a smoothed torque value, an insufficiency output unit to determine insufficient pedal input torque, and an assist torque calculating unit that mixes the smoothed torque value with pedal input torque to calculate assist torque, ensuring sufficient assistance at the start and suitable target torque calculation for varying torque requests.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If assist torque is calculated by simply multiplying pedal input torque by assist ratio, then the control is simple, but the assist is weak at points where pedal pedaling force cannot be applied and the sensation of assistance is not good
Solution Approach 1:
The patent applies preliminary action by calculating a target torque value in advance that includes both the assist torque component and a make-up torque component. This target torque is calculated before the actual torque application, allowing the system to proactively compensate for valleys in pedaling force rather than reactively responding to them. The make-up torque is pre-calculated based on the difference between target torque and actual pedal input torque, ensuring smooth assistance sensation.
Solution Approach 2:
The patent introduces an intermediary calculation process that computes target torque as a mediator between the raw pedal input torque and the final assist torque. This intermediary target torque value smooths out fluctuations in pedaling force by adding a make-up torque component, which acts as a buffer between the irregular pedal input and the motor output, thereby improving the sensation of assistance.
2Loss of energy
If assist torque is calculated by simply multiplying pedal input torque by assist ratio, then the control is simple, but the assist torque is temporarily great and peak motor driving current is great, causing greater loss from electric efficiency perspective
Solution Approach 1:
The system performs preliminary calculation of target torque that incorporates both assist torque and make-up torque components. By calculating the required make-up torque in advance based on the difference between target torque and actual pedal input, the system can smooth out torque fluctuations before they reach the motor, thereby reducing peak current demands and improving electric efficiency.
Solution Approach 2:
The patent changes the torque parameter by introducing a make-up torque component that compensates for valleys in pedaling force. This parameter modification transforms the assist torque calculation from a direct multiplication of pedal torque by assist ratio to a more sophisticated formula that adds a compensatory component, thereby reducing torque ripple and peak current while maintaining assistance effectiveness.
3Stability of the object's composition
If delaying time of assisting driving force is made proportionate to pedaling force cycle, then uniform and constant combined force can be supplied, but the assisting driving force cannot handle starting from a stopped state
Solution Approach 1:
The patent applies preliminary action by calculating the target torque value in advance, which includes both the assist torque component and a make-up torque component. This pre-calculation allows the system to provide immediate assistance from a stopped state by computing the full target torque including the make-up portion, rather than relying on delayed assistance based on detected pedaling cycles.
Solution Approach 2:
The patent introduces dynamics by making the make-up torque calculation adaptive to different operating conditions. The system dynamically adjusts the target torque based on real-time pedal input torque and vehicle speed, allowing it to handle both starting from stopped state and maintaining uniform force during pedaling. This dynamic approach replaces the fixed delay-time mechanism with a flexible, condition-based torque calculation.
4Power
If restricting assisting force when pedal pedaling force is below threshold value, then optimal assist ratio can be decided, but restriction is applied even at the point of starting to pedal when great torque is desired
Solution Approach 1:
The patent applies preliminary action by calculating the target torque value in advance that includes both assist torque and make-up torque components. This pre-calculation ensures that when the rider starts pedaling, the system immediately provides the full target torque including the make-up portion, rather than restricting assistance based on threshold comparisons of detected pedaling force.
Solution Approach 2:
The patent introduces dynamics by making the torque calculation adaptive to different operating conditions including starting from stopped state. The system dynamically adjusts the target torque based on real-time pedal input torque and vehicle speed, allowing it to provide great torque when starting while maintaining optimal assist ratio during normal pedaling, replacing the static threshold-based restriction with a dynamic calculation approach.
Data Source
AI summary
This motor driving control apparatus includes: a smoothing processing unit that executes smoothing processing using values of pedal input torque at plural points to calculate a first smoothed torque value; an insufficiency output unit that obtains a rate of points at which input of the pedal input torque is insufficient among the plural points; an assist torque calculating unit that performs calculation processing of mixing the first torque value calculated by the smoothing processing unit and the pedal input torque in accordance with output of the insufficient output unit to calculate assist torque; and a driving processing unit that performs processing to drive a motor using the assist torque calculated by the assist torque calculating unit.