Electric Machine Transition Control Reducing Transient Phase Currents
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Solution Overview
Problem
Existing methods for transitioning an electric machine from freewheel to active short circuit operation result in high transient phase currents, which can reduce component lifespan and require over-dimensioning of components, leading to increased costs.
Innovation Solution
A device and method that control the transition from freewheel to active short circuit by monitoring voltage ratios and rotor position, initiating the change when voltage reaches a predetermined value, using semiconductor switches and freewheel diodes to manage electrical connections, thereby reducing transient phase currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the transition from freewheel to active short circuit is initiated immediately when voltage exceeds a limit value, then the response time is fast, but high transient phase currents occur which reduce component lifespan and require over-dimensioning
Solution Approach 1:
The control device monitors voltage ratios in advance and waits for the optimal moment (when voltage ratio is maximum) before initiating the transition from freewheel to active short circuit. This preliminary monitoring and timing strategy prevents high transient phase currents while maintaining fast response, thereby extending component lifespan without sacrificing response speed.
2Reliability
If components are over-dimensioned to handle high transient phase currents, then reliability is improved, but device complexity and cost increase
Solution Approach 1:
The invention changes the timing parameter of the transition from freewheel to active short circuit to occur when the voltage ratio is maximum. This parameter optimization reduces transient phase currents to acceptable levels, allowing components to be dimensioned appropriately rather than over-dimensioned, thereby maintaining reliability while reducing device complexity and cost.
3Object-generated harmful factors
If the transition is delayed until voltage ratio is maximum, then transient phase currents are reduced, but response time increases
Solution Approach 1:
The control device continuously monitors voltage ratios in real-time and uses this feedback to determine the optimal transition moment. This feedback mechanism ensures the transition occurs precisely when voltage ratio is maximum, minimizing transient phase currents while maintaining the fastest possible response time given the electrical conditions.
4Object-generated harmful factors
If voltage monitoring is performed continuously to determine optimal transition moment, then transient phase currents are reduced, but measurement and control complexity increases
Solution Approach 1:
The control device performs voltage ratio monitoring as part of its existing control functions for the electric machine. By integrating the monitoring of voltage ratios into the existing control architecture that already manages freewheel and active short circuit operations, the patent reduces measurement and control complexity while still achieving optimal transition timing to minimize transient phase currents.
Data Source
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AI summary
The invention results in improved switching from the idling mode to an active short circuit mode of an electric machine. According to the invention, the switch from the idling mode to the active electric short circuit mode is delayed until predefined voltage conditions have been reached on the external terminals of an electric machine or until the rotor of the electric machine is in a predetermined position corresponding to the required voltage conditions.