Star-Connected Power Semiconductors for Synchronous Machine Fault Protection
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Solution Overview
Problem
Existing drive systems for battery-powered vehicles experience unintended braking torque and overvoltage issues due to faults in the self-commutated converter or its control and regulating device, particularly in field weakening mode, leading to instability and potential damage or injury.
Innovation Solution
A drive system utilizing three disconnectable power semiconductors connected in star configuration with a high-resistance resistor to the DC voltage-side connection of the self-commutated converter, allowing for controlled short-circuiting of stator-side connections of a permanently excited synchronous machine, thereby minimizing braking torque and enabling external control of armature short-circuiting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the self-commutated converter or control device fails, then the drive system experiences unintended braking torque and overvoltage, but the vehicle stability and driver safety are compromised
Solution Approach 1:
The patent applies preliminary anti-action by providing an external armature short-circuit device that can preemptively counteract the harmful braking torque and overvoltage effects before they fully manifest. When converter faults are detected or anticipated, the external short-circuit device activates to neutralize the unintended braking torque and protect the vehicle stability, rather than waiting for the system to fail completely.
Solution Approach 2:
The external armature short-circuit device serves as a cushioning mechanism that absorbs and mitigates the harmful effects of converter failures. By providing a predetermined protective pathway for current discharge, the system cushions against the shock of sudden failures, preventing catastrophic instability and driver injury while maintaining overall system reliability.
2Reliability
If armature short-circuiting is used to prevent overvoltage, then overvoltage is minimized, but sudden braking torque occurs causing vehicle instability
Solution Approach 1:
The patent introduces an intermediary external armature short-circuit device that mediates between the converter system and the motor armature. This external device provides a controlled pathway for current during short-circuit conditions, allowing overvoltage protection to be achieved while the control system can manage the braking torque effects separately, thus decoupling the two harmful effects.
Solution Approach 2:
The patent replaces the traditional mechanical braking system with an electrical control mechanism. Instead of relying on mechanical brakes to control vehicle deceleration, the system uses electronic control of the armature short-circuit timing and duration to manage braking torque, allowing for smoother and more controllable deceleration that maintains vehicle stability.
3Productivity
If the self-commutated converter is used for frequency conversion, then the synchronous machine can operate efficiently, but faults in the converter cause unintended braking and overvoltage
Solution Approach 1:
The patent segments the frequency conversion function into two independent parts: the self-commutated converter for normal efficient operation, and the external armature short-circuit device for fault protection. This segmentation allows the main converter to operate at high efficiency while the external protective device remains dormant during normal operation and activates only when needed, maintaining productivity while improving reliability.
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 solution allows for targeted switching and cancellation of armature short-circuits, maintaining vehicle stability and preventing sudden braking, thus protecting the driver and other vehicles from unexpected braking events caused by converter or control device faults.
Implementation Method 1
drei schaltbaren Leistungshalbleitern, die elektrisch sternförmig geschaltet sind und deren freie Verbindungen jeweils mit einer statorseitigen Verbindung einer Permanentmagnet-Synchronmaschine verbunden sind, wobei ein Sternpunkt der drei elektrisch sternförmig geschalteten schaltbaren Leistungshalbleiter über einen Hochohmigen Widerstand mit einer Gleichspannungsseitigen Verbindung eines pulsweitenmodulierten Umrichters verbunden ist
Implementation Method 2
drei schaltbaren Leistungshalbleitern, die elektrisch sternförmig geschaltet sind und deren freie Verbindungen jeweils mit einer statorseitigen Verbindung einer Permanentmagnet-Synchronmaschine verbunden sind
Data Source
Figure 1
Figure 2~3
Figure 4
AI summary
The system has a control device (26) controlling short circuit of stator-side terminals (U-W) of a permanent magnet synchronous machine (10). Three disconnectable power semiconductors (T12, T14, T16) of the control device are electrically connected in a star connection. Idle terminals (48, 50, 52) of the semiconductors are connected to the stator-side terminals in an electrically conducting manner. A neutral point (44) of the connection is connected to direct voltage (DC) terminals (DC, DC+) of a self-commutated converter (8) by a high-ohmic resistor (46) in an electrically conductive manner. The power semiconductors are designed as insulated gate bipolar transistors or MOSFETs. The self-commutated converter is designed as a three-phase self-commutated converter.