Regenerative Braking Control for Wide-Speed Motor Vehicles
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Solution Overview
Problem
Existing motor vehicles with regenerative braking systems face challenges in generating intended braking torque over a wide rotation range of the motor, particularly due to decreased motor electromotive voltage at low-speed rotation and the need for field weakening control at high-speed rotation, which reduces maximum braking torque.
Innovation Solution
The motor vehicle incorporates a regenerative braking system that generates a predetermined braking torque based on the operation amount of the regenerative brake operator when the motor rotation speed is equal to or higher than a predetermined value, using a power converter with voltage step-up and step-down functions to optimize energy recovery and supply.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If field weakening control is used to suppress inverter DC voltage at high-speed rotation, then the inverter DC voltage is controlled, but the maximum braking torque of regenerative braking decreases
Solution Approach 1:
The patent changes the control parameters by introducing a rotation speed threshold value. When motor rotation speed is below this threshold, field weakening control is not applied, allowing maximum braking torque to be maintained. When rotation speed exceeds the threshold, field weakening control is activated to suppress inverter DC voltage. This parameter-based switching resolves the contradiction by optimizing control strategy based on operating conditions.
2Loss of energy
If regenerative braking is used to recover energy, then energy is stored in the power storage device, but the braking torque intended by the driver cannot be obtained at high rotation speeds
Solution Approach 1:
The patent introduces a rotation speed threshold parameter to determine when field weakening control should be applied. By setting this threshold appropriately, the system ensures that regenerative braking provides intended braking torque across the entire rotation range. Below the threshold, full braking torque is available; above the threshold, field weakening is applied to maintain voltage control while preserving adequate braking capability.
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 enables the generation of intended braking torque by regenerative braking over a wide motor rotation range, improving energy regeneration efficiency and reducing the frequency of mechanical brake use, thus enhancing vehicle performance and extending mechanical brake durability.
Implementation Method 1
a motor configured to perform power driving and regeneration
Implementation Method 2
The motor electromotive voltage decreases in a low-speed rotation range of the motor. Therefore, regenerative braking cannot be used.
Implementation Method 3
An inverter converts a direct current into an alternating current
Implementation Method 4
A mechanical brake performs braking by releasing energy
Data Source
AI summary
A motor performing power driving and regeneration has an inverter, a mechanical brake, a power storage device supplying energy to the motor, an accelerator operator controlling the motor to adjust a drive torque of a driving wheel, a mechanical brake operator controlling the mechanical brake to adjust a braking torque, a regenerative brake operator adjusting a braking torque of the driving wheel and recovering the energy into the power storage device, and a detector detecting a rotation speed of the motor. When the rotation speed of the motor is equal to or higher than a predetermined value, a predetermined braking torque, based on an operation amount of the regenerative brake operator, is generated by regenerative braking.