Inverter Control for Electric Machine Back-EMF Fault Protection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
High-voltage electric power circuits with electric machines face challenges in managing open circuit and short circuit faults, which can lead to uncontrolled generator modes, compromising system stability and efficiency.
Innovation Solution
A control system that monitors back-emf voltage levels and adjusts the inverter operation to a three-phase open state when the back-emf is below a maximum setpoint voltage and to a three-phase short state when it exceeds this level, preventing uncontrolled generator modes and ensuring stable operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the inverter operates in uncontrolled generator mode due to open circuit or short circuit faults, then the electric machine can continue to generate power, but system stability is compromised and demagnetization may occur
Solution Approach 1:
The control system continuously monitors back-emf voltage levels and uses this feedback to determine the appropriate inverter operating state. When back-emf exceeds the maximum setpoint voltage, the system transitions to three-phase short state; when below the setpoint, it transitions to three-phase open state. This closed-loop feedback mechanism prevents uncontrolled generator mode while maintaining system stability.
Solution Approach 2:
The inverter operating state is dynamically adjusted based on real-time back-emf voltage conditions. The system transitions between three-phase open state and three-phase short state depending on whether the back-emf voltage is below or above the maximum setpoint voltage, respectively. This dynamic adaptation allows the system to respond appropriately to changing operational conditions and prevent fault states.
2Reliability
If the inverter is controlled to three-phase open state when back-emf is below maximum setpoint voltage, then system stability is maintained, but energy management efficiency may be reduced
Solution Approach 1:
The control system changes the operating parameters of the inverter based on the back-emf voltage level. When back-emf is below the maximum setpoint voltage, the system adopts three-phase open state with specific voltage and current parameters; when back-emf exceeds the setpoint, it switches to three-phase short state. This parameter adaptation optimizes energy management while maintaining stability.
3Reliability
If the inverter is controlled to three-phase short state when back-emf exceeds maximum setpoint voltage, then demagnetization is prevented, but energy losses increase
Solution Approach 1:
The control system takes preliminary protective action by detecting when back-emf voltage approaches the maximum setpoint level and preemptively transitioning to three-phase short state. This prevents the harmful effect of demagnetization before it can occur, while the temporary increase in energy losses is acceptable compared to the catastrophic damage of demagnetization.
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 effectively mitigates faults by maintaining system stability, preventing demagnetization, and minimizing energy addition to the DC power source, thus avoiding uncontrolled generator states and ensuring efficient power management.
Implementation Method 1
monitors back-emf voltage level from the electric machine. The inverter is controlled to a three-phase open state when the back-emf voltage level is less than the maximum setpoint voltage level. The inverter is controlled to a three-phase short state when the back-emf voltage level is greater than the maximum setpoint voltage level.
Data Source
AI summary
An electric power system for supplying power to a permanent magnet electric machine includes a high-voltage DC power source that is disposed to supply electric power to a front-end converter connected via a high-voltage DC bus to an electric inverter that is connected to the electric machine. A method for operating a control system includes monitoring the electric machine. Upon detecting a fault associated with the electric machine, a controller commands operation of the front-end converter to generate a voltage level on the high-voltage DC bus that is a maximum setpoint voltage level and monitors back-emf voltage level from the electric machine. The inverter is controlled to a three-phase open state when the back-emf voltage level is less than the maximum setpoint voltage level. The inverter is controlled to a three-phase short state when the back-emf voltage level is greater than the maximum setpoint voltage level.