Parallel Inverter Control via Serial Data Transmission
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Solution Overview
Problem
High-power three-phase inverter stages connected in parallel face challenges with increased cabling complexity, limited scalability, and susceptibility to errors due to long transmission paths and limited data transmission rates, which can lead to faulty activation and reduced service life of switching elements.
Innovation Solution
A method where switching elements are controlled via a central unit using serial data transmission, with each permitted overall switching state assigned a unique 10-bit transmission sequence differing by at least four bits, ensuring reliable and fast control by allowing only bit sequences within a predetermined group to change the switching state, reducing wiring and enabling synchronous control without direct connections between inverter stages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If parallel connection of inverter stages is used to handle high currents, then current handling capability is improved, but cabling complexity and wiring effort increase significantly
Solution Approach 1:
Multiple inverter stages are connected in parallel to a common DC link, merging their current handling capabilities while sharing common busbars and control infrastructure, thereby reducing individual stage complexity and overall system wiring
Solution Approach 2:
The control unit is designed to universally control multiple inverter stages through a single serial interface, eliminating the need for separate control units and their associated wiring for each stage, thus reducing cabling complexity while maintaining scalable current handling
2Power
If more inverter stages are connected in parallel, then current handling capability is improved, but transmission path length increases causing higher error susceptibility
Solution Approach 1:
A robust serial communication protocol acts as an intermediary between the central control unit and multiple inverter stages, providing error detection, synchronization, and reliable data transmission over extended distances, thereby maintaining reliability despite increased transmission path length
Solution Approach 2:
The control system implements feedback mechanisms where measurement data from each inverter stage is transmitted back to the central control unit via the serial interface, enabling real-time monitoring and error correction, which maintains system reliability across extended transmission paths
3Speed
If control unit is placed close to inverter stage, then control speed is improved, but control complexity and wiring requirements increase
Solution Approach 1:
A single central control unit is merged to control all parallel-connected inverter stages through a high-speed serial interface, consolidating control functions and eliminating the need for multiple distributed control units, thereby reducing overall control complexity while maintaining fast response times
4Reliability
If conventional parallel control with direct connections is used, then control reliability is improved, but device complexity and cabling requirements increase
Solution Approach 1:
A carefully designed serial communication protocol serves as an intermediary that provides reliable control signal transmission with built-in error detection and synchronization mechanisms, achieving control reliability equivalent to direct parallel connections while dramatically reducing device complexity and cabling requirements
Data Source
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AI summary
The invention relates to a method for actuating inverter stages (2) connected in parallel, wherein each inverter stage (2) comprises a plurality of switching elements (30), each having two switching states. In accordance with the invention, the actuation of the inverter stages (2) takes place via a central regulation unit (6), which is connected to each inverter stage (2) via a serial data transmission path (5). For the transmission of the selected switching states from the central regulation unit (6) to the corresponding inverter stage (2), measures are proposed firstly for ensuring safe operation of the inverter stages (2) via a multiplicity of switching operations and reliably avoiding functional impairments of the switching elements (3) owing to faulty actuation, but secondly for performing the actuation of the switching elements (3) of the inverter stages (2) also sufficiently quickly in order not to impair the quality of the output current formed by the inverter stage (2).