Three-Phase Inverter Short-Circuit Detection Without Full Shutdown
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Solution Overview
Problem
In electric motor drivetrains, particularly in vehicles and aircraft, existing technologies fail to promptly detect phase-to-phase short circuits in inverters, leading to potential motor failure and system crashes due to hazardous overcurrents, which can result in inverter damage and loss of drive function.
Innovation Solution
A method and arrangement for identifying and compensating inverter short circuits between two phases by measuring AC current values across all three phases, determining temporal current changes, and reconfiguring the energy supply network to prevent damage and maintain system functionality by modifying inverter modulation to avoid overcurrents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional overcurrent protection is used to detect phase-to-phase short circuits, then inverter damage is prevented, but system functionality is completely lost due to total shutdown
Solution Approach 1:
The invention segments the protection response by identifying which specific phase pair is short-circuited and only blocking the affected switches rather than shutting down the entire inverter. This allows the healthy phases to continue operating, maintaining partial system functionality while protecting the inverter from damage.
Solution Approach 2:
The system dynamically adapts its operation mode based on the detected fault condition. Instead of a static all-or-nothing shutdown, the inverter transitions to a degraded mode where it continues operating with reduced capacity, adjusting its switching strategy to avoid the short-circuited phase pair while maintaining drive function.
2Reliability
If prompt detection of short circuits is implemented to prevent inverter destruction, then inverter reliability is improved, but drive function is completely lost
Solution Approach 1:
The protection mechanism is segmented to affect only the specific phase pair involved in the short circuit rather than the entire three-phase system. By identifying the affected phases and selectively blocking only those switches, the system maintains drive function in the healthy phases while protecting the inverter.
Solution Approach 2:
The system changes its operational parameters dynamically based on the fault condition. It modifies the switching states of specific phases while maintaining normal operation in healthy phases, allowing continued drive function at reduced capacity rather than complete shutdown.
3Object-affected harmful factors
If all switches are blocked to prevent overcurrent damage, then inverter safety is ensured, but system adaptability is reduced
Solution Approach 1:
The switch blocking is segmented to affect only the specific switches associated with the short-circuited phase pair rather than all switches in the inverter. This selective approach protects the inverter from overcurrent damage while maintaining adaptability through continued operation of healthy phases.
Solution Approach 2:
The system dynamically adjusts its switching configuration based on the detected fault, transitioning from normal three-phase operation to a degraded mode with modified switching patterns. This maintains system adaptability by allowing continued operation in healthy phases while protecting against damage.
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
The solution allows for the prompt identification and mitigation of short circuits, preventing inverter damage and maintaining system functionality, ensuring safety and operational integrity, especially in critical applications like electric aircraft.
Implementation Method 1
a second current circuit of which includes a three-phase current circuit that is supplied with phase-offset AC voltages by the bridge circuit of the inverter
Implementation Method 2
AC current values of all three phases in an energy supply network are measured. Values of a temporal current change are also identified based on the measured AC current values
Implementation Method 3
The short circuit bridges the inductance of the motor installed in the IT network; as a result of this, the effective overall inductance is considerably reduced. A current that rises very quickly per cycle is thereby generated
Data Source
AI summary
A method for identifying an inverter short circuit between two phases includes measuring AC current values of three phases. Values of a temporal current change are also identified based on the measured AC current values. A short circuit between two phases is then assumed if, in one phase at DC+ and one phase at DC−, the current rises more quickly or falls more quickly than a predetermined threshold value. In order to check this assumption, it is identified whether the value of the identified rise in a first phase possibly affected by the short circuit corresponds to the value of the identified fall in a second phase possibly affected by the short circuit. In the event that the assumption has been positively confirmed, it is also checked whether a current sum of the phases is still unchanged. A short circuit is established when the two checks have proven positive.