Multiphase Electric Machine Control With Harmonic-Aware Inductance Modeling
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Solution Overview
Problem
Existing methods for operating electrical machines with machine models require significant computational effort due to the complexity of inverting position-dependent inductance matrices, especially for multi-phase machines with higher order harmonics, which are not accurately accounted for in conventional approaches.
Innovation Solution
A modified machine model using a reshaped inductance matrix that combines phase and coupling inductances, accounting for all terms and harmonics, reduces computational complexity by simplifying the inversion process and allowing precise modeling of electrical machine behavior.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional inversion methods for the inductance matrix are used, then 2nd order harmonics can be taken into account, but higher order harmonics (1st, 3rd, 4th and above) are not accounted for and the computational effort remains high
Solution Approach 1:
The patent segments the inductance matrix inversion problem by introducing an intermediate transformation matrix that separates the handling of different harmonic orders. This allows systematic inclusion of higher order harmonics through structured matrix operations rather than attempting to process all harmonics simultaneously in a single complex inversion.
Solution Approach 2:
The patent transforms the problem from direct inductance matrix inversion to a two-stage process involving transformation matrices that operate in different dimensional spaces. The intermediate matrix serves as a bridge between the phase domain and the harmonic domain, enabling efficient computation of multiple harmonic orders.
2Device complexity
If a star connection of phase strands is used, then the inductance matrix can be reduced to a 2×2 matrix, but this is associated with considerable computational effort
Solution Approach 1:
Instead of directly inverting the reduced 2×2 matrix, the patent applies an intermediate transformation that reformulates the problem. The transformation matrix approach avoids direct inversion operations on the reduced matrix, replacing them with more computationally efficient matrix multiplications and transformations.
3Productivity
If simplification of the machine model by assuming position independent coupling inductances is used, then computational effort is reduced, but this is not expedient for consequential pole machines with higher order harmonics
Solution Approach 1:
The patent changes the parameter representation from position-dependent coupling inductances to a transformation matrix framework that inherently captures position-dependent behavior through harmonic components. This allows the model to maintain accuracy for consequential pole machines while using computationally efficient matrix operations.
Data Source
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AI summary
The invention relates to a method for the controlled operation of a multiphase electric machine (2) with several phase strands (23) connected in a star configuration, comprising the following steps: - providing a control deviation, - controlling the operation of the electric machine (2) depending on computationally determined actual phase currents in order to provide terminal potential values (Sa, Sb, Sc) for controlling an inverter (3), which accordingly applies terminal potentials (Va, Vb, Vc) to the electric machine (2), wherein the actual phase currents (Iaist, Ibist, Icist) are determined using a machine model depending on the terminal potentials (Va, Vb, Vc) and the control deviation, wherein the machine model depends on an inductance matrix that determines the magnetic properties of the electric machine (2) such that these voltage differences between the terminal potentials (Va, Vb, Vc) are mapped to the actual phase currents (Iaist, Ibist, Icist).