Electric Wheelchair Regenerative Braking Control for Charging Current Limits
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Solution Overview
Problem
Existing electric wheelchairs face challenges in effectively controlling the charging current generated by regenerative braking, particularly when traveling downhill, which can lead to excessive charging currents and reduced battery capacity.
Innovation Solution
A driving system for electric wheelchairs that includes a controller to monitor the charging current and adjust the travel speed based on threshold values, decelerating the wheelchair when the current exceeds a predetermined level to prevent excessive charging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If regenerative braking is used to charge the battery during downhill travel, then the maximum travel distance is increased, but the charging current becomes excessively large
Solution Approach 1:
The controller continuously monitors the charging current generated by regenerative braking and uses this feedback to dynamically adjust the upper limit speed value. When the charging current exceeds a threshold, the controller reduces the upper limit speed to prevent excessive current, thereby resolving the contradiction between maximizing travel distance through regenerative braking and preventing dangerous current levels
Solution Approach 2:
The system dynamically adjusts the upper limit speed value based on real-time charging current conditions rather than maintaining a fixed speed limit. This dynamic adjustment allows the wheelchair to optimize travel distance through regenerative braking while adaptively preventing excessive charging current by reducing speed when necessary
2Quantity of substance
If the upper limit speed value is reduced to prevent excessive charging current, then the charging current is controlled, but the travel speed becomes lower than desired
Solution Approach 1:
The upper limit speed value is dynamically adjusted based on charging current conditions rather than being fixed. When charging current is within acceptable ranges, the upper limit speed remains high to maintain desired travel speed. Only when charging current exceeds thresholds does the system reduce the upper limit speed, thereby minimizing the impact on normal travel while ensuring safety
3Quantity of substance
If the controller continuously monitors and adjusts speed based on charging current, then the charging current is controlled, but the control system becomes more complex
Solution Approach 1:
The controller uses feedback from current sensors to monitor charging current and automatically adjusts the upper limit speed value through a standardized control algorithm. This feedback mechanism provides effective charging current control through software logic rather than complex hardware circuitry, minimizing the increase in overall system complexity
Solution Approach 2:
The system controls charging current by changing the speed parameter (upper limit speed value) rather than directly controlling current through complex circuitry. This parameter-based control approach simplifies the control system by using software adjustments to speed limits rather than requiring complex current regulation hardware
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The system effectively manages the charging current, preventing it from becoming too large, thereby maintaining optimal battery charging and extending the wheelchair's travel distance.
Implementation Method 1
at least one electric motor to generate a driving force to cause the electric wheelchair to travel
Implementation Method 2
the electric motor is caused to generate rotation in response to a user operation on the controller
Implementation Method 3
By generating a braking force by regenerative braking when an electric wheelchair is traveling downhill
Implementation Method 4
By charging the battery with the current generated by regenerative braking
Data Source
AI summary
A driving system for use in an electric wheelchair includes at least one electric motor, a battery to supply power to the at least one electric motor, a controller configured or programmed to control operation of the at least one electric motor, a speed sensor to output a signal regarding a travel speed of the electric wheelchair, and a current sensor to output a signal regarding a current flowing through an electric path between the at least one electric motor and the battery. The controller is configured or programmed to obtain a current value of a charging current generated by regenerative braking to charge the battery and to decelerate the travel speed of the electric wheelchair based on the current value.