Inverter Control Device Homopolar Vector Selection
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Solution Overview
Problem
Existing control methods for inverters connected to multi-phase electrical engines either fail to apply homopolar components when needed or introduce parasitic homopolar components, leading to inefficiencies and potential engine damage.
Innovation Solution
A control device for an inverter that selects a combination of statuses associated with both zero-sum and non-zero-sum vectors in the vector space, allowing for the generation of setpoint vectors with or without homopolar components, thereby reducing the risk of parasitic homopolar component application while enabling necessary homopolar component application.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the Z-SVM Vector MLI control method is used to ensure phase voltages have no homopolar component, then the reliability of the engine is improved, but the adaptability to apply homopolar components when needed is lost
Solution Approach 1:
The control method dynamically adapts between two operational modes: using only non-homopolar vectors (N vectors) when homopolar component is not needed, and incorporating homopolar vectors (N+1 vectors) when homopolar component is required. This dynamic switching resolves the contradiction between reliability and adaptability.
Solution Approach 2:
The method changes the parameter of vector selection by detecting whether a homopolar component is present in the setpoint vector. Based on this detection, it adjusts the set of available vectors from N non-homopolar vectors to N+1 vectors including homopolar vectors, thereby adapting to different operational requirements.
2Adaptability or versatility
If the 3-Level Intersective MLI control method is used to allow homopolar component application, then the adaptability is improved, but parasitic homopolar components are introduced causing harmful effects
Solution Approach 1:
The method extracts and separates the homopolar component detection from the vector selection process. By detecting the homopolar component in the setpoint vector and conditionally selecting only appropriate vectors, it eliminates the introduction of parasitic homopolar components while maintaining the ability to apply legitimate homopolar components when needed.
Solution Approach 2:
The control method incorporates feedback by detecting whether the setpoint vector contains a homopolar component and using this information to adjust the vector selection. This feedback mechanism ensures that vectors are chosen to match the actual requirements, preventing parasitic homopolar components from being introduced.
3Ease of operation
If all 27 inverter statuses are used to maximize control flexibility, then the ease of operation is improved, but the manufacturing precision of voltage application deteriorates due to parasitic components
Solution Approach 1:
The method applies local quality by treating different regions of the vector space differently. Based on the detected homopolar component in the setpoint vector, it selects vectors with appropriate properties: non-homopolar vectors when precision is critical and homopolar vectors when flexibility is needed, thereby optimizing both ease of operation and voltage application precision locally.
Data Source
AI summary
The control device includes: a unit for receiving, for a time period, phase voltage setpoints forming a setpoint vector in vector space; a unit for selecting at least N+1 states of the inverter which are associated, respectively, with at least N+1 predetermined vectors (M1 . . . M27) defining a volume in the vector space (Esp) containing the setpoint vector; a unit for controlling the inverter, over the time period, in order to place it successively in the selected states so that it substantially applies, on average over the time period, the phase voltage setpoints. The at least N+1 states of the inverter are selected from among groups of at least N+1 states of the inverter, the at least N+1 states of the inverter of at least one of the groups being associated, respectively, with at least N+1 predetermined vectors (M1 . . . M27), at least N of which are formed by predetermined zero-sum phase voltages and at least one of which is formed by predetermined nonzero-sum phase voltages.