Motor Drive Fail-Safe Circuits Prevent Short Circuit Heat
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Solution Overview
Problem
Existing motor driving systems in electric vehicles face challenges in maintaining efficient operation and preventing unnecessary short circuits when a failure occurs, leading to potential braking issues and heat generation due to regeneration torque, especially when power sources are compromised.
Innovation Solution
The electromechanical system incorporates a configuration with a main battery, auxiliary battery, DC bus line capacitor, current sensors, and a motor driving apparatus that includes fail-safe circuits and gate driving circuits to detect motor rotation speed and control switching devices, preventing short circuits by switching states based on detected conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If all upper-arm-side switching devices or all lower-arm-side switching devices are turned on to short circuit the motor during failure, then motor control can be maintained, but unnecessary short circuits and heat generation occur
Solution Approach 1:
The patent applies dynamics by making the switching device states changeable based on operating conditions. Instead of statically maintaining all switching devices in one state, the system dynamically adjusts which switching devices are on or off based on real-time motor rotation speed detection and failure type identification, thereby avoiding unnecessary short circuits while maintaining motor control reliability.
Solution Approach 2:
The patent changes the parameter of switching device states based on detected conditions. By detecting motor rotation speed and determining failure types, the system adjusts the on/off states of switching devices accordingly - for example, turning off switching devices when rotation speed is below a threshold to prevent unnecessary short circuits and heat generation, while maintaining the ability to control the motor when conditions are appropriate.
2Device complexity
If switching devices are kept in fixed states during failure, then motor control is simplified, but braking issues and heat generation occur due to regeneration torque
Solution Approach 1:
The system dynamically adjusts switching device states based on real-time detection of motor rotation speed and failure conditions. This dynamic approach allows the system to respond to changing conditions such as regeneration torque, turning off switching devices when rotation speed is low to prevent heat generation, while maintaining simplified control logic through clear decision criteria.
3Reliability
If power source failure is detected, then system safety is improved, but motor control capability is reduced
Solution Approach 1:
The patent changes the operational parameters of the motor control system based on power source failure detection. By detecting failures in the first power source and adjusting the control strategy accordingly - such as using the second power source and modifying switching device states based on rotation speed thresholds - the system maintains motor control capability while ensuring safety through adaptive parameter changes.
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 configuration effectively prevents unnecessary short circuits and heat generation by ensuring fail-safe operation even when power sources are compromised, maintaining efficient motor control and reducing the risk of braking issues.
Implementation Method 1
DC bus line capacitor
Implementation Method 2
current sensors, and a motor driving apparatus that includes fail-safe circuits and gate driving circuits to detect motor rotation speed
Implementation Method 3
control switching devices, preventing short circuits by switching states
Data Source
AI summary
Provided is a motor driving apparatus including: an upper-arm gate driving circuit; a lower-arm gate driving circuit; a first rotation detection unit powered by a first power source; a second rotation detection unit powered by a second power source; a first fail safe circuit that performs, by use of a detection signal from the first rotation detection unit, a fail safe control on a gate driving circuit powered at least by the first power source, from among the upper-arm gate driving circuit and the lower-arm gate driving circuit; and a second fail safe circuit that performs, by use of a detection signal from the second rotation detection unit, a fail safe control on a gate driving circuit powered at least by the second power source, from among the upper-arm gate driving circuit and the lower-arm gate driving circuit.