Motor Control Device Back-EMF Management
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Solution Overview
Problem
In automotive applications, electric motors face challenges with excessive back electromotive force (EMF) and heat generation, which can damage controllers and other electronics, and existing thermal protection systems like PTC thermal breakers can cause sudden operational halts and are not suitable for compact packaging.
Innovation Solution
The use of electronic control methods to manage back EMF by diverting excessive voltage to the vehicle battery and regulating heat generation through cycle limitation, energy consumption monitoring, and failure mode detection, eliminating the need for physical components like clutches and PTC thermal breakers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If electronic control mechanisms are used to replace structural control mechanisms like clutches and PTC thermal breakers, then device complexity is reduced and space is saved, but thermal protection and heat management become more challenging
Solution Approach 1:
The patent replaces mechanical and thermal structural control mechanisms (clutches, PTC thermal breakers) with electronic control systems that use sensors, microcontrollers, and electronic switching devices to monitor and manage motor operation, thermal conditions, and power delivery, thereby eliminating bulky mechanical components while maintaining or improving control precision and thermal management capability
Solution Approach 2:
The patent introduces electronic intermediaries such as current sensors, temperature sensors, and electronic control units that act as mediators between the motor and the control system, enabling precise monitoring and regulation of thermal and electrical parameters without requiring direct mechanical or thermal contact, thus achieving thermal protection through electronic means rather than structural mechanisms
2Volume of moving object
If electronic control mechanisms replace structural control mechanisms, then space within motor housing is saved, but heat dissipation and thermal management become more difficult
Solution Approach 1:
The patent replaces thermal management mechanisms that occupy physical space (such as PTC thermal breakers and mechanical clutches) with electronic control systems that monitor temperature via sensors and manage heat through electronic power regulation, allowing for more compact motor housing while maintaining effective thermal management through software-based thermal models and real-time parameter adjustment
3Loss of energy
If back EMF is allowed to exceed battery voltage, then energy can be recovered and stored in the battery, but excessive voltage can damage the controller and electronics
Solution Approach 1:
The patent employs feedback control mechanisms where current sensors continuously monitor the current flowing from the motor during regenerative braking, and the microcontroller adjusts the switching duty cycle of the power electronics to regulate the voltage level, ensuring that energy is recovered and stored in the battery while preventing excessive back EMF voltage from damaging the controller and electronic components
Solution Approach 2:
The patent introduces electronic intermediaries including current sensors, voltage regulators, and electronic switching devices (such as MOSFETs or IGBTs in an H-bridge configuration) that act as mediators between the motor and the battery, enabling controlled energy transfer during regenerative braking while protecting the system from voltage spikes and excessive back EMF through active voltage clamping and current limiting
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 from excessive back EMF and heat-related issues, allowing for compact motor designs with advanced thermal management that anticipates and mitigates overheating, reducing unexpected system failures.
Implementation Method 1
excessive back electromotive force (EMF) and heat generation
Implementation Method 2
clamping the circuit path to the battery such that an excess voltage above the battery voltage is transferred from the electric motor to the battery
Implementation Method 3
heat generated by an electric motor
Data Source
AI summary
A system and method for preventing thermal damage to an electric motor in a vehicle includes arrangements for monitoring the motor and detecting a cycle of the motor. If the cycle occurred within a predetermined increment time, a cycle count is incremented. If no cycle occurs for a predetermined decrement time, the cycle count is decremented if the cycle count is greater than zero. If the cycle count is at least equal to a cycle limit, power operation of the motor is deactivated for at least the decrement time. The method may include continuously calculating energy consumed by the motor and, if the energy consumed exceeds one or more allowable energy thresholds, setting the cycle count equal to the cycle limit. The method may further include detecting a failure condition and setting the cycle count equal to the cycle limit when the failure condition is detected.