Galvanic Isolation in Electric Drive Inverter Systems
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Solution Overview
Problem
Existing electric drive systems with multiple parallel inverter units are prone to failure, causing the entire system to halt if one unit malfunctions, lacking adequate fault tolerance and requiring shutdown for maintenance or replacement.
Innovation Solution
The system is designed with modular, separable units where supply and inverter units can be galvanically separated from the intermediate circuit and electric machine, allowing for continued operation with redundant units and enabling faulted components to be replaced without shutting down the system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple parallel inverter units are connected to a common intermediate circuit, then the system can provide redundant capacity, but a malfunction in one unit causes the entire system to halt
Solution Approach 1:
The patent divides the electric drive system into separate galvanically isolated units, each with its own intermediate circuit and control. This segmentation allows one unit to fail without affecting others, as each unit operates independently. The electric machine is divided into multiple windings that can be controlled by different inverter units, enabling partial operation when some units fail.
Solution Approach 2:
The patent introduces an intermediary control system that manages multiple galvanically isolated inverter units. This intermediary coordinates the operation of separate units, allowing them to work together to control the electric machine while maintaining galvanic isolation. The intermediary enables seamless switching between units and maintains system operation even when individual units fail.
2Ease of repair
If inverter units are permanently connected to the intermediate circuit, then the system structure is simplified, but faulty components require system shutdown for replacement
Solution Approach 1:
The patent implements dynamic reconfigurability where inverter units can be galvanically connected or disconnected from the intermediate circuit based on operational needs or fault conditions. This dynamic capability allows faulty units to be isolated and replaced without shutting down the entire system, as healthy units continue to operate and can be reconnected when ready.
Solution Approach 2:
The patent prepares the system for potential failures by pre-configuring galvanic isolation capabilities and redundant units. When a fault occurs, the system can immediately isolate the faulty component without requiring shutdown, as the isolation mechanism is already in place. This beforehand preparation minimizes downtime and allows continuous operation with remaining healthy units.
3Reliability
If supply units are galvanically connected to the intermediate circuit, then power transmission is efficient, but a supply fault propagates through the entire system
Solution Approach 1:
The patent segments the power supply system into multiple galvanically isolated supply units, each connected to the intermediate circuit through isolation barriers. This segmentation prevents fault propagation between supply units while maintaining efficient power transmission to their respective loads. Each supply unit operates independently with its own intermediate circuit connection.
Data Source
AI summary
A method and arrangement in connection with an electric drive system are provided. The electric drive system includes an intermediate circuit with two or more supply units and two or more inverter units connected thereto, and an electric machine having two or more three-phase windings galvanically separated from each other. Two or more inverter units are connected to the three-phase windings. The arrangement also includes first main circuit switches to galvanically separate each supply unit from a supply, second main circuit switches to galvanically separate each supply unit from the intermediate circuit, first intermediate circuit switches to galvanically separate each inverter unit from the intermediate circuit, and second intermediate circuit switches to galvanically separate each inverter unit from the electric machine.