PMSM Loss-Power Control Using Tracking Differentiator

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Solution Overview

Problem

Existing electric machine control algorithms for permanent-magnet synchronous machines are inefficient due to high computational requirements and significant dependence on machine parameters, leading to suboptimal efficiency and slow optimization processes.

Innovation Solution

A control method that calculates loss power based on input and output power differences, using a tracking differentiator to quickly determine a target d-axis current, reducing dependence on machine parameters and optimizing efficiency by adjusting the duty ratio for the inverter to minimize loss power.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the search algorithm is used to optimize efficiency by adjusting control variables, then the algorithm is robust to parameter changes, but it involves large computational amounts and takes long time to optimize

Engineering Contradiction:

Improverobustness to parameter changesVSAvoidoptimization speed

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The patent pre-calculates and stores the relationship between loss power and d-axis current in a lookup table during system initialization or offline operation. During real-time control, the controller directly queries this pre-computed table to obtain optimal d-axis current values, eliminating the need for complex real-time calculations while maintaining optimization accuracy and robustness

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent creates a simplified computational model by copying the essential relationship between loss power and d-axis current into a lookup table structure. This copy allows rapid retrieval of optimal parameters without performing the full computational algorithm, achieving fast response while preserving the optimization logic

Inventive Principle:

Principle #26Copying

2Productivity

If the loss model algorithm is used to build a loss model based on electric machine parameters, then the algorithm responds quickly with good dynamic performance, but the optimization effect depends greatly on the parameters of the electric machine

Engineering Contradiction:

Improveresponse speedVSAvoiddependence on machine parameters

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent implements a feedback mechanism where the actual loss power (calculated from measured input and output power) is continuously compared with the loss power predicted by the model. The lookup table is updated or adjusted based on this feedback to compensate for parameter variations, ensuring accurate optimization even when machine parameters change due to temperature, aging, or manufacturing tolerances

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent transforms the optimization problem from directly controlling d-axis current to controlling loss power as the intermediate parameter. By using loss power (derived from measurable input and output power) as the control target and querying the lookup table with actual loss power values, the system adapts to parameter changes without requiring precise knowledge of machine parameters

Inventive Principle:

Principle #35Parameter changes

3Reliability

If complex control algorithms are used to optimize efficiency, then the optimization effect can be improved, but the computational burden increases

Engineering Contradiction:

Improveefficiency optimization effectVSAvoidcomputational complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent performs the computationally intensive optimization calculations offline or during system initialization, building a lookup table that maps loss power values to optimal d-axis current values. During real-time operation, the controller simply queries this pre-computed table, reducing real-time computational burden to minimal table lookup operations while maintaining optimal efficiency control

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent replaces complex real-time computational algorithms with a simple lookup table structure that requires minimal processing resources. The lookup table acts as a pre-computed solution that can be quickly queried without demanding high computational power during operation, making the system suitable for embedded controllers with limited processing capabilities

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

Data Source

PatentEP4164115B1Control method, apparatus and system for electric motor, and electric vehicle

Publication Date: 2023.09.27 CONTEMPORARY AMPEREX TECHNOLOGY CO LTD

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AI summary

This application provides an electric machine control method and device, a system, and an electric vehicle. The method includes: obtaining an input power and an output power of an electric machine; calculating a loss power based on the input power and the output power; determining a target d-axis current of the electric machine, where the target d-axis current is calculated by a calculation module based on the loss power, the calculation module includes a tracking differentiator, and the calculation module operates in a controller; and determining a duty ratio based on the target d-axis current and a preset q-axis current, and inputting the duty ratio into an inverter so that the inverter drives, based on the duty ratio, the electric machine to operate. In the embodiments of this application, the loss power of the permanent-magnet synchronous machine is input into the tracking differentiator. The tracking differentiator can obtain the target d-axis current quickly, thereby greatly reducing the dependence on parameters of the permanent-magnet synchronous machine and reducing the amount of computing.