EV Battery Regenerative Braking PWM Control
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Solution Overview
Problem
In electric vehicles with regenerative braking architectures that do not require additional hardware circuits, excessive charge current during prolonged braking can trigger battery protection mechanisms, risking damage to the motor or battery pack.
Innovation Solution
A battery regenerative breaking control method that determines the battery pack's protection status and adjusts pulse width modulation (PWM) duty cycle and frequency to manage charge current, reducing the risk of damage by converting excessive kinetic energy into heat energy without additional hardware.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If regenerative braking is implemented without additional hardware circuits, then device complexity is reduced and cost is lowered, but excessive charge current during prolonged braking triggers battery protection mechanisms, risking damage to motor or battery pack
Solution Approach 1:
The patent implements dynamic switching between two PWM control modes (first PWM mode and second PWM mode) based on real-time detection of battery protection status. When battery protection is detected, the system switches from the first PWM mode to the second PWM mode, dynamically adjusting control parameters to prevent damage while maintaining regenerative braking functionality without additional hardware circuits.
Solution Approach 2:
The patent changes PWM control parameters (duty cycle and frequency) based on battery protection status. In the first PWM mode, different duty cycles are applied to different phases based on current magnitude. In the second PWM mode, the PWM frequency is increased to a higher frequency range, effectively changing the control parameters to manage excessive charge current and prevent battery or motor damage.
2Use of energy by moving object
If PWM duty cycle is adjusted to manage charge current, then energy recycling efficiency is improved, but complex control logic is required to switch between different PWM modes
Solution Approach 1:
The patent employs parameter changes in PWM control to manage energy recycling. By adjusting duty cycle in the first PWM mode and frequency in the second PWM mode, the system optimizes energy recovery while adapting to different operating conditions, including battery protection states, thereby maintaining high energy recycling efficiency.
Solution Approach 2:
The system incorporates feedback by detecting battery protection status in real-time and using this information to switch between PWM modes. This feedback mechanism enables the control system to adapt its behavior based on battery conditions, ensuring safe operation while maintaining efficient energy recycling without requiring additional hardware circuits.
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 method effectively recycles energy while preventing damage to the motor and battery pack by controlling PWM adjustments to manage charge current, ensuring safe operation during regenerative braking.
Implementation Method 1
adjusts pulse width modulation (PWM) duty cycle and frequency to manage charge current, reducing the risk of damage by converting excessive kinetic energy into heat energy
Data Source
AI summary
A battery regenerative breaking control method applied in an electric vehicle is provided. The battery regenerative breaking control method includes: determining whether a battery pack is at a protection status when the electric vehicle is detected to be at a regenerative breaking status; recording a current battery error time point and obtaining a time threshold according to a current speed of the electric vehicle if it is determined that the battery pack is at the protection status; determining whether a current time is smaller than the time threshold; entering a first stage to adjust a pulse width modulation (PWM) duty cycle if the current time is smaller than the time threshold; and entering a second stage to adjust a PWM frequency if the current time is larger than the time threshold.