Inverter-Based FOC Parameter Tuning for Electric Motor Efficiency

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Solution Overview

Problem

Existing electric motor control algorithms face challenges in accurately determining key motor parameters, which are crucial for optimal performance, as these parameters vary between motors and are essential for efficient operation across a wide range of speeds and power levels in vehicles, leading to suboptimal energy efficiency.

Innovation Solution

A computer-implemented method and apparatus that determines parameters of a field-oriented control model for electric power units by sending control signals to the inverter drive, applying predefined voltages, measuring currents, and adjusting signals to accurately determine parameters, including resistance, inductance, and magnetization characteristics, thereby accounting for distortions in the inverter circuit and wiring effects.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If traditional motor control algorithms are used with fixed parameters, then the control system is simple to implement, but the energy efficiency deteriorates because parameters vary between motors and operating conditions

Engineering Contradiction:
Improveenergy efficiencyVSAvoidcontrol system complexity
Core Design Contradiction:
Use of energy by moving objectVSDevice complexity

Solution Approach 1:

The system performs preliminary identification of motor parameters before actual operation begins. The identification routine executes during motor standstill or low-speed operation to determine parameters such as resistance, inductance, and flux linkage constants. These pre-identified parameters are then stored and used during normal operation, eliminating the need for continuous complex measurements while maintaining high energy efficiency across varying operating conditions.

Inventive Principle:
Principle #10Preliminary action

2Measurement precision

If parameter determination is performed offline separately, then measurements can be precise, but the process time increases and parameters may not reflect actual operating conditions

Engineering Contradiction:
Improveparameter determination accuracyVSAvoidparameter determination time
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The system performs parameter identification continuously during motor operation rather than requiring separate offline measurement sessions. The identification routine can execute during standstill periods, low-speed operation, or transitions between operating modes, ensuring parameters are always current without interrupting normal motor function. This continuous approach maintains measurement precision while eliminating time losses associated with separate offline calibration procedures.

Inventive Principle:
Principle #20Continuity of useful action

Solution Approach 2:

The system performs preliminary identification of motor parameters before actual operation begins. The identification routine executes during motor standstill or low-speed operation to determine parameters such as resistance, inductance, and flux linkage constants. These pre-identified parameters are then stored and used during normal operation, eliminating the need for continuous complex measurements while maintaining high energy efficiency across varying operating conditions.

Inventive Principle:
Principle #10Preliminary action

3Measurement precision

If separate offline measurements are used for parameter determination, then equipment complexity is reduced, but the accuracy deteriorates due to distortions in inverter circuit and wiring effects

Engineering Contradiction:
Improveparameter determination accuracyVSAvoidmeasurement system complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The system uses the inverter drive itself as an intermediary measurement tool. The inverter's existing voltage and current sensors, along with its control processing unit, are utilized to perform parameter identification. By leveraging the inverter's inherent measurement capabilities and control algorithms, the system achieves accurate parameter determination that accounts for inverter circuit distortions and wiring effects, without requiring separate external measurement equipment.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The inverter drive performs parameter identification autonomously using its own control processing unit and sensors. The system self-determines its operating parameters without external intervention or separate measurement devices. The inverter's control algorithm executes identification routines, processes measurement data, and updates motor parameters automatically, making the system self-sufficient and eliminating the need for additional external measurement equipment.

Inventive Principle:
Principle #25Self-service

4Adaptability or versatility

If manual parameter tuning is performed, then adaptability to different motors is improved, but productivity decreases due to time-consuming adjustments

Engineering Contradiction:
Improvemotor compatibilityVSAvoidsetup speed
Core Design Contradiction:
Adaptability or versatilityVSProductivity

Solution Approach 1:

The inverter drive performs parameter identification autonomously using its own control processing unit and sensors. The system self-determines its operating parameters without external intervention or separate measurement devices. The inverter's control algorithm executes identification routines, processes measurement data, and updates motor parameters automatically, making the system self-sufficient and eliminating the need for additional external measurement equipment.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The system performs preliminary identification of motor parameters before actual operation begins. The identification routine executes during motor standstill or low-speed operation to determine parameters such as resistance, inductance, and flux linkage constants. These pre-identified parameters are then stored and used during normal operation, eliminating the need for continuous complex measurements while maintaining high energy efficiency across varying operating conditions.

Inventive Principle:
Principle #10Preliminary action

Data Source

PatentEP3713078B1Automatic software tool for tuning of electric motor control parameters
Publication Date: 2024.07.24 ZAPI
  • EP3713078B1 patent drawingFigure 1~2
  • EP3713078B1 patent drawingFigure 3
  • EP3713078B1 patent drawing

AI summary

The invention refers to a computer-implemented method for determining a parameter of a field-oriented control, FOC, model for an electric power unit, the electric power unit comprising a three-phase electric motor and an inverter drive for driving the electric motor, the method comprising the steps of: sending a control signal to the inverter drive; applying a predefined electric voltage to at least two of the phases of the electric motor by the inverter drive in response to the control signal; measuring an electric current that flows in the at least two phases of the electric motor in response to the applied electric voltage; and determining the parameter of the control model for the electric power unit using a value of the applied predefined electric voltage and a value of the measured electric current. Further, a corresponding apparatus for determining a parameter of a control model for an electric power unit is provided. The accuracy of the parameters determined by the method according to the invention is based on the precision of the applied voltages and for this reason it is necessary to foresee a hardware and software function to obtain this precision.