Hybrid Vehicle Regenerative Braking Control for Transformer Thermal Limits
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Solution Overview
Problem
In vehicles equipped with transformers for regenerative braking, the increased power generated during deceleration can lead to limited regenerative braking torque, causing a mismatch with the driver's intended setting and resulting in an uncomfortable driving experience due to the need to protect components from heat-related issues.
Innovation Solution
A travel driving apparatus that includes an electrical motor, a battery, a transformer with limited maximum input/output power based on temperature, a regenerative braking force selecting section, and a computing section to adjust the braking force stepwisely, ensuring minimal required regenerative braking force while protecting the transformer, and optionally notifying the driver of excessive selections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the transformer is used to step up voltage for driving the electric motor during regenerative braking, then power can be transformed and stored in the battery, but the transformer's maximum input/output power is limited due to heat protection, causing regenerative braking torque to be limited and braking force to decrease
Solution Approach 1:
The system dynamically adjusts the regenerative braking force based on the transformer's temperature condition and power limits. When the transformer is not limited, the full selected regenerative braking force is applied. When the transformer is limited, the system computes a reduced regenerative braking force that keeps the transformer input power below its maximum limit, while still maintaining a minimum necessary braking force for safety and drivability.
Solution Approach 2:
The system changes the regenerative braking force parameter based on the transformer's operational state. The regenerative braking force computing section calculates an appropriate braking force that adapts to the transformer's temperature and power capacity, ensuring the transformer operates within safe parameters while maintaining acceptable braking performance.
2Reliability
If the regenerative braking torque is limited to protect the transformer, then the transformer is protected from overheating, but the braking force becomes insufficient and does not match the driver's intended operation, causing uncomfortable driving experience
Solution Approach 1:
When the transformer is limited, the system applies partial regenerative braking force rather than the full force selected by the driver. The regenerative braking force computing section calculates a reduced force that is sufficient to protect the transformer while still providing meaningful braking assistance, rather than completely disabling regenerative braking.
Solution Approach 2:
The notification section provides feedback to the driver when the selected regenerative braking force cannot be fully applied due to transformer limitations. This feedback mechanism informs the driver of the mismatch between their selection and the actual applied braking force, managing expectations and improving the perceived ease of operation.
3Force
If the regenerative braking force is increased beyond the transformer's power limit, then the driver's intended braking force is achieved, but the transformer may overheat and be damaged
Solution Approach 1:
The system takes preliminary action to prevent transformer overheating by computing and limiting the regenerative braking force before the transformer is subjected to excessive power. The regenerative braking force computing section proactively calculates a safe braking force that keeps the transformer input power below its maximum limit, preventing heat generation that could lead to damage.
Solution Approach 2:
The system performs preliminary computation of the appropriate regenerative braking force based on the transformer's current temperature and power capacity. This preliminary action ensures that the transformer operates within safe parameters from the start, preventing harmful heat accumulation before it can cause damage.
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 solution ensures minimal regenerative braking force during deceleration, maintaining drivability and protecting the transformer, while allowing for adjustable regenerative braking force settings that match the vehicle's traveling range, and notifies the driver of non-matching selections, thus enhancing the driving experience.
Implementation Method 1
a transformer for transforming the power regenerated by the electrical motor and supplying the power to the battery
Implementation Method 2
the electric motor generates power as well as brakes the vehicle during deceleration of the vehicle
Data Source
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AI summary
In a hybrid vehicle including: a step-up converter (15) for stepping-up the voltage from a battery (8) and supplying power to the front motor (3) for driving front wheels; as well as a paddle switch (31) for setting regenerative braking torque stepwisely, and a hybrid control unit (20) for calculating a regenerative braking force based on a selection stage set by the paddle switch (31), the hybrid control unit (20) decreases the regenerative braking force to be less than the regenerative braking force while the maximum input/output power of the step-up converter (15) is not limited, when a selection stage in which regenerative braking force is more than that in a D range is selected while the maximum input/output power of the step-up converter (15) is limited.