Electric Machine Harmonic Filtering for Stable Motor Control
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Solution Overview
Problem
Existing methods for controlling electric machines struggle to robustly and stably manage harmonics, leading to vibrations and structure-borne sound due to non-ideal sinusoidal magnetic fields and mechanical transmission behaviors.
Innovation Solution
A method involving a first and second filter to isolate and remove harmonic components from the feedback variable in a field-oriented system, allowing for the energization of the electric machine based on a filtered feedback variable without harmonics, using notch filtering and low-pass filtering techniques.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If harmonics are controlled by adjusting phase current harmonics, then harmonic disturbance variables are minimized, but the control becomes less robust and stable
Solution Approach 1:
The patent extracts harmonic components from the feedback variable by subtracting the fundamental component (obtained through filtering) from the total feedback variable. This separation allows independent control of fundamental and harmonic components, enabling robust harmonic minimization without compromising overall control stability. The harmonic component is isolated and can be controlled separately through the controller.
2Reliability
If multiple filter stages are used to remove harmonic components, then control stability is improved, but device complexity increases
Solution Approach 1:
The filtering process is segmented into distinct functional stages: first filter for fundamental component extraction, second filter for harmonic component extraction, and combination stage for reconstructing the controlled feedback variable. This segmentation allows each filter to be optimized independently and simplifies the overall design compared to a single complex filter system.
3Productivity
If the feedback variable contains both fundamental and harmonic components, then complete machine operation is maintained, but vibrations and structure-borne sound increase
Solution Approach 1:
The patent implements a feedback mechanism where the controlled feedback variable (with minimized harmonics) is used to generate control signals that adjust the phase current. The controller continuously monitors the effect of harmonic minimization and adjusts the control signals accordingly, maintaining stable machine operation while reducing vibrations and structure-borne sound through iterative harmonic compensation.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach effectively minimizes harmonic disturbance variables, reducing vibrations and improving the operational stability and flexibility of electric machine control by isolating and removing harmonic components, thereby enhancing the control of electric machines.
Implementation Method 1
filtering a specifiable fundamental DC reference variable by means of the first filter
Implementation Method 2
filtering the filtered feedback variable without a fundamental component by means of at least one second filter
Data Source
AI summary
The invention relates to a method (400) for regulating an electric machine (190), comprising at least one first filter (140) and at least one second filter (142, 144). The method has the steps of: ascertaining (410) a feedback variable (Idq); filtering (412) a specifiable GW matching variable (Idq*); ascertaining (414) the filtered feedback variable without fundamental components (IdqWo-Funda); filtering (416) the filtered feedback variable without fundamental components (IdqWo-Funda); ascertaining (418) a filtered feedback variable without harmonic components (IdqFunda); and energizing (480) at least one winding of the electric machine (190) on the basis of the filtered feedback variable without harmonic components (IdqFunda).