Electric Motorcycle Braking Beyond Battery Charge Limits
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Solution Overview
Problem
The existing braking systems in electrically driven motorcycles are limited by the maximum charging power of the drive energy store, which restricts the braking power available through recuperation, making it difficult to fulfill driver braking intentions, especially when the charging power is low.
Innovation Solution
A method that utilizes an additional braking device separate from the electrical drive motor, which detects the required braking torque and adjusts the electrical drive motor's efficiency and power loss to supplement the braking torque, ensuring that the braking intention is met independently of the charging power, by using an additional braking device such as a friction brake, eddy current brake, or electromechanical parking brake.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the electrical drive motor is operated as a generator for recuperation braking, then energy is recovered and fed into the drive energy store, but the braking power is limited by the maximum charging power of the drive energy store
Solution Approach 1:
The braking system is segmented into multiple independent braking devices: the electrical drive motor (for recuperation), additional braking devices (friction brakes, eddy current brakes, or parking brakes), and power loss generation means. This segmentation allows each component to contribute to braking independently, so when recuperation power is insufficient, other braking devices can supplement without being constrained by the drive energy store's charging capacity.
Solution Approach 2:
The system dynamically changes operational parameters by adjusting the efficiency of the electrical drive motor and controlling power loss generation based on real-time conditions. When maximum charging power is insufficient, the system reduces motor efficiency and generates additional power loss to maintain required braking torque, thereby adapting the braking strategy to available charging capacity.
2Loss of energy
If the maximum charging power is low, then energy recuperation is limited, but the braking torque requirement must still be fulfilled
Solution Approach 1:
The control unit continuously monitors and determines the present maximum charging power of the drive energy store in advance before braking is required. This preliminary assessment allows the system to pre-calculate the available recuperation capability and plan the braking strategy accordingly, ensuring that when braking is needed, the system can immediately deploy the appropriate combination of braking devices to meet the torque requirement.
Solution Approach 2:
The control unit acts as an intermediary that coordinates between the electrical drive motor, additional braking devices, and power loss generation means. It determines the present additional braking torque required and distributes the braking demand across available components, ensuring reliable braking performance even when recuperation capacity is limited by the drive energy store's charging power.
3Power
If additional braking devices are used to supplement braking torque, then braking intention can be fulfilled, but wear and power consumption increase
Solution Approach 1:
The system converts what would normally be wasted energy into useful braking torque by generating power loss through controlled reduction of electrical drive motor efficiency. This approach provides additional braking force without using mechanical friction brakes, thereby preventing wear while still fulfilling the braking torque requirement. The power loss is intentionally generated as a beneficial braking mechanism rather than treated as harmful waste.
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
This method ensures that every braking intention is fulfilled, maintains high braking torque, minimizes the use of the additional braking device, and maximizes energy recuperation, while reducing wear and power consumption, ensuring efficient braking across varying charging power conditions.
Implementation Method 1
the electrical drive motor for decelerating the vehicle can be operated as a generator, wherein part of the kinetic energy of the vehicle is recovered as electrical energy
Implementation Method 2
at least one additional braking device that is separate from the electrical drive motor
Data Source
AI summary
An electrically driven motorcycle includes a drive energy store, an on-board electrical system, a motor, a braking device, and a control unit. A method to brake the motorcycle includes detecting currently required braking torque, current maximum charge power of the drive energy store, current maximum power loss that can be generated in the motor and/or on-board electrical system, currently required power loss resulting from a difference in current maximum charge power and maximum power recovery of the motor for the required braking torque, and an additional braking device braking torque resulting from a difference in required braking torque and motor braking torque resulting from the current maximum charge power and the current maximum power loss that can be applied, and controlling the motor and/or the on-board electrical system with reduced efficiency such that the required power loss is achieved, and actuating the braking device to apply the additional braking torque.