Vehicle Door Driver Circuit for Back-EMF Overvoltage Protection
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Solution Overview
Problem
Automatic vehicle doors generate large back electromotive force (EMF) voltages when manually operated, which can damage the control system without requiring significant physical space for protection components.
Innovation Solution
A system transitions a driver from a disabled to an enabled state when a back EMF voltage exceeds a threshold, using a half-bridge IC with a high-side and low-side switch to short the voltage to ground through the low-side switch.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a passive component (e.g., diode) is included in the control system to protect against back EMF voltages, then the control system is protected from damage, but the physical space required in the control system increases
Solution Approach 1:
The patent introduces an intermediary protection circuit that includes a comparator and transistor to detect and respond to back EMF voltages. This intermediary mechanism monitors the voltage at the driver output and activates protection only when necessary, replacing the need for always-present passive protection components and reducing overall space requirements on the PCB.
Solution Approach 2:
The protection system uses the existing driver circuitry's own components (low-side switch, output stage) to provide protection against back EMF. When overvoltage is detected, the system automatically activates the low-side switch to short the output to ground, utilizing the driver's existing infrastructure rather than requiring separate dedicated protection components.
2Use of energy by moving object
If the driver is kept in disabled state to save power, then energy consumption is reduced, but the system cannot respond quickly when back EMF occurs
Solution Approach 1:
The protection circuit performs preliminary monitoring of the driver output voltage continuously or at regular intervals using the comparator. This preliminary detection mechanism is always active or can be quickly activated, so when back EMF occurs, the system is already prepared to respond immediately without needing to wake from a deep disabled state, thus maintaining both low power consumption and fast response capability.
Solution Approach 2:
The system dynamically transitions the driver between disabled and enabled states based on operational needs. The protection circuit ensures that when transitioning from disabled to enabled state, the system is ready to detect and respond to back EMF conditions. This dynamic state management allows the system to optimize power consumption while maintaining the capability for rapid protection response when needed.
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
Prevents damage to the control system by effectively shorting high EMF voltages to ground, protecting the system without occupying excessive space.
Implementation Method 1
short the back EMF voltage to ground through the low-side switch
Data Source
AI summary
Systems and methods are provided for protecting a door system from damage by a back electromotive force (EMF) voltage generated when a door coupled to a door actuator is manually closed. The door system may include a driver configured to drive the door actuator to move the door, and a back EMF protection circuit. The back EMF protection circuit detects a back EMF voltage generated by the door actuator when the door is moved, and determines whether the back EMF voltage exceeds an overvoltage threshold. In response to determining that the back EMF voltage exceeds the overvoltage threshold, the back EMF protection circuit causes the driver to transition to an enabled state to short the back EMF voltage to ground.