Electric Drive Train Control via Selective Stator Coil Short-Circuiting
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In electric vehicle propulsion systems, particularly with synchronous rotating electric machines, failures in the inverter can lead to excessively high voltages at the stator terminals, causing untimely braking or deterioration of switching cells, as existing solutions like reducing the maximum no-load electromotive force (emf0 max) result in unsafe current levels.
Innovation Solution
A method for controlling the electric propulsion system by applying an auxiliary command to short-circuit specific coils of the stator winding, ensuring the voltage across non-short-circuited coils remains below a threshold, thereby preventing excessive voltage and potential damage, using a switching system with multiple arms and DC/AC voltage converter architecture.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the maximum no-load electromotive force (emf0 max) of the electric machine is reduced to limit terminal voltage, then the voltage induced at the terminals remains below dangerous values, but the electrical current increases significantly to dangerous levels
Solution Approach 1:
The patent segments the stator winding into multiple independent coils that can be selectively short-circuited. Instead of treating the entire winding as a single unit, the control system can individually manage specific coils based on operating conditions, allowing precise voltage control without affecting the entire system's current-carrying capacity.
Solution Approach 2:
The patent applies partial short-circuiting of coils rather than complete short-circuiting of the entire stator winding. By short-circuiting only specific coils when needed, the system limits voltage to safe levels during abnormal operations while maintaining adequate current capacity for normal propulsion functions.
2Ease of operation
If the autonomous electrical energy source is connected to the inverter, then the system can operate normally, but the voltage at the terminals can become higher than the source voltage and charge the source causing untimely braking
Solution Approach 1:
The patent implements preliminary protective action by detecting abnormal voltage conditions and automatically short-circuiting specific stator coils before the reverse charging effect can occur. This preventive measure blocks the harmful feedback to the battery while maintaining system operation.
Solution Approach 2:
The patent introduces an intermediary control mechanism (the selective coil short-circuiting system) between the inverter and the autonomous energy source. This intermediary action regulates the voltage interaction, allowing normal operation while preventing harmful reverse charging effects.
3Reliability
If the inverter operates as a rectifier due to failure, then the system continues to function, but high voltages are induced at the stator terminals causing safety issues
Solution Approach 1:
The patent implements a feedback control mechanism that continuously monitors the operating mode of the inverter and the voltage levels at the stator terminals. When the inverter fails to operate in inversion mode and instead functions as a rectifier, the system detects this condition and automatically activates coil short-circuiting to limit induced voltages to safe levels.
Solution Approach 2:
The patent introduces dynamic adaptability by enabling the stator winding configuration to change in real-time based on operating conditions. The selective coil short-circuiting capability allows the system to dynamically adjust its electrical characteristics, maintaining safety margins even when operating in abnormal rectifier mode.
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 approach enhances safety by preventing untimely braking and switching cell deterioration, maintaining voltage within safe limits while managing current levels effectively.
Implementation Method 1
a switching system interposed between the autonomous electrical energy source and the electrical stator winding
Implementation Method 2
the voltage induced across the terminals of each phase of the stator can reach high values
Data Source
Figure 1~2
Figure 3~6b
AI summary
A method for controlling the electric drive train (1) of a vehicle, said train comprising: - a polyphase electrical machine (4), comprising a stator electrical winding having a plurality of coils each forming an electrical phase of the stator, - a self-contained electric power source (2) powering the stator electrical winding of the machine (4), and - a switching system (3) interposed between the self-contained electric power source (2) and the stator electrical winding and comprising a plurality of switching cells (10), method which involves: - applying a control to the switching system (3) in order to operate the electric drive train (1) according to a predefined mode, - detecting a difference between the actual operating mode of the drive train (1) and the predefined operating mode, and - applying an auxiliary control to the switching system (3), said auxiliary control short-circuiting only a portion of the coils of the stator electrical winding such that the voltage at the terminals of each non-short-circuited coil is lower than a given threshold value.