Inverter Control Circuit Phase Reconfiguration for Motor Drive Fault Tolerance
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional power conversion devices for electric motors face challenges in performing suitable current control under both normal and abnormal conditions, particularly due to power loss and inability to form a closed loop for drive current when a neutral point is formed in a failed inverter.
Innovation Solution
A power conversion device with a control circuit that changes from n-phase conduction control to m-phase conduction control using different phases when a failure is detected, ensuring suitable current control by reconfiguring the control of the first and second inverters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If n-phase conduction control is used under normal conditions, then motor performance is optimized, but the system cannot operate reliably when a switching element fails
Solution Approach 1:
The control circuit dynamically switches between n-phase conduction control mode (under normal conditions) and m-phase conduction control mode (under abnormal conditions with switching element failure). This dynamic adaptation ensures the motor can operate reliably across different operational states, resolving the contradiction between optimized normal performance and fault tolerance.
Solution Approach 2:
The system changes the control parameter from n-phase conduction to m-phase conduction when a failure is detected. By modifying the conduction phase parameter, the system adapts to abnormal conditions while maintaining motor operation, thus improving reliability without sacrificing control effectiveness.
2Reliability
If neutral point is formed in a failed inverter, then motor can continue operation, but power loss occurs and closed loop for drive current cannot be formed
Solution Approach 1:
The detection circuit identifies and extracts the failed switching element from the system, allowing the control circuit to exclude the failed inverter phase from active conduction. By taking out the failed component from the operational loop, the system prevents power loss while maintaining continued operation through the remaining healthy phases.
Solution Approach 2:
The control circuit acts as an intermediary that redirects current flow away from the failed inverter phase. By mediating the power distribution, it prevents energy loss in the failed component while ensuring closed loop current paths are formed through the operational phases, thus resolving both continued operation and power loss issues.
3Reliability
If detection circuit is added to detect switching element failures, then fault tolerance is improved, but device complexity increases
Solution Approach 1:
The detection circuit functions are merged with the existing control circuit, allowing failure detection capabilities to be integrated into the existing control architecture. This merging approach improves fault tolerance while minimizing the increase in device complexity by utilizing shared hardware resources and integrated processing.
Data Source
AI summary
A power conversion device may include a first inverter to which a first end of each phase winding is coupled; a second inverter to which a second end of each phase winding is coupled; a plurality of switching elements provided in the first and second inverters; a control circuit structured to perform n-phase conduction control on the first and second inverters; and a detection circuit structured to detect a failure in the switching elements. The control circuit is structured such that, when the detection circuit has detected a failure in any of the plurality of switching elements, the control circuit changes the control of the first and second inverters from the n-phase conduction control to m-phase conduction control using m phases of the n phases different from the phase of a winding coupled to the failed switching element, m being an integer not smaller than two and smaller than n.