Multi-Winding Machine Flux Control for Fast Torque Response
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Solution Overview
Problem
Existing model predictive pulse pattern control (MP3C) methods are designed for electrical machines with only one set of three-phase windings and cannot be directly applied to machines with multiple sets of windings, leading to suboptimal performance and increased current ripple due to the need for low-pass filtering and constraints on switching angles.
Innovation Solution
A method that extends MP3C to electrical machines with multiple sets of windings by determining average and difference flux references, which are then translated into winding flux references for each winding system, allowing independent model predictive control of each converter branch, and modifying switching instants to minimize flux error.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If low-pass filtering is applied to measured currents to extract fundamental component, then current ripple is reduced, but controller gain is limited and drive dynamic performance deteriorates
Solution Approach 1:
The patent extracts and controls the instantaneous flux directly without filtering out the ripple components. By working with the complete flux signal including harmonics, the method eliminates the need for low-pass filtering while maintaining accurate torque control, thus preserving dynamic performance while avoiding the limitations imposed by filtering.
Solution Approach 2:
The patent pre-calculates the reference flux trajectory including all harmonic components before control execution. This preliminary determination of the complete flux reference (with ripple) allows the controller to anticipate and compensate for harmonics in advance, eliminating the need for post-acquisition filtering and maintaining both low ripple and high dynamic performance.
2Stability of the object's composition
If switching angles of OPPs evolve smoothly without discontinuities, then control stability is improved, but current ripple increases due to suboptimal OPPs
Solution Approach 1:
The patent transitions from static, pre-calculated switching angles to dynamic, real-time optimization of OPPs. By continuously adjusting switching angles based on instantaneous flux error and machine state, the system can accept discontinuities in switching angle evolution, achieving both low current ripple and control stability through adaptive optimization rather than rigid smoothness constraints.
Solution Approach 2:
The patent changes the optimization parameters of OPPs in real-time based on operating conditions and flux error. This dynamic parameter adjustment allows switching angles to discontinuously change when beneficial for ripple reduction, overcoming the limitation of requiring smooth angle evolution while maintaining control stability through the overall feedback structure.
3Speed
If MP3C controls instantaneous flux along reference trajectory including ripple, then torque control speed is improved, but application to multi-winding machines becomes complex
Solution Approach 1:
The patent segments the control of multi-winding machines into independent per-phase flux control loops. Each winding phase has its own flux reference trajectory and MP3C controller, allowing the complex multi-winding system to be managed as multiple simpler single-phase control problems. This segmentation maintains fast torque control while reducing overall system complexity through modular architecture.
Solution Approach 2:
The patent creates a universal MP3C control framework that handles multiple winding types (wye-connected, delta-connected, independent windings) through a single unified approach. The same basic control algorithm applies to each winding regardless of connection type, providing multi-functionality that reduces complexity compared to designing separate control schemes for each winding configuration.
Data Source
AI summary
A method for controlling an electrical converter is disclosed. First, an average flux reference is determined from a reference torque and an estimated torque. At least one difference flux reference is determined from at least one difference current reference. A winding flux reference for each winding system is determined from the average flux reference and the at least one difference flux reference by adding and/or subtracting the at least one difference flux reference to the average flux reference. Switching commands for each converter branch are determined from the winding flux reference and an estimated winding flux for the winding system, which is connected to the respective converter branch. The winding flux reference and the estimated winding flux are provided to a dedicated model predictive controller for the respective converter branch, which determines the switching commands; and applying the switching commands to each converter branch.