Induction Motor Start Frequency Control for High Torque Efficiency

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Solution Overview

Problem

Existing induction motor control methods face challenges in improving operating efficiency and starting capacity without increasing the cost of inverter power semiconductors, as they often require increased current redundancy to enhance starting torque, leading to higher inverter costs.

Innovation Solution

A method for controlling induction motors that involves obtaining initial equivalent parameters, determining optimal starting and operation frequencies, and adjusting driving voltage based on real-time motor speed to maintain steady-state operation, optimizing starting capability and efficiency without increasing inverter costs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the current redundancy of power semiconductors is increased to enhance starting torque and overload capacity, then the starting capability and reliability are improved, but the cost of the inverter increases

Engineering Contradiction:
Improvestarting capabilityVSAvoidinverter cost
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The patent determines optimal starting frequency and operation frequency based on equivalent circuit parameters, transforming the control approach from current redundancy to frequency optimization. This allows achieving better starting performance without increasing power semiconductor current capacity, thereby reducing inverter cost while maintaining reliability

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent performs preliminary determination of equivalent circuit parameters and calculates optimal starting frequency before the motor starts. This preliminary optimization of control parameters enables the motor to achieve maximum starting torque with minimal current, avoiding the need for oversized power semiconductors

Inventive Principle:
Principle #10Preliminary action

2Use of energy by moving object

If variable frequency speed control is used to improve operating efficiency at light loads, then energy efficiency is improved, but the system complexity increases

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

Solution Approach 1:

The patent implements self-service through automatic determination of equivalent circuit parameters and autonomous calculation of optimal frequencies. The system automatically adjusts operating parameters based on real-time motor state without requiring complex external control intervention, thereby improving energy efficiency while keeping control system complexity manageable

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The patent dynamically adjusts the operation frequency based on the motor's equivalent circuit parameters and operating conditions. This dynamic optimization allows the motor to operate at peak efficiency across varying load conditions, improving overall energy utilization without requiring overly complex static control systems

Inventive Principle:
Principle #15Dynamics

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 method enhances starting torque and operating efficiency of induction motors by accurately determining optimal frequencies and voltages, ensuring smooth transitions and reducing energy consumption, thus improving performance and extending the motor's service life without increasing inverter costs.

Implementation Method 1

induction motor

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Data Source

PatentEP4708663A1Method for controlling induction motor, device, equipment, and storage medium
Publication Date: 2026.03.11 FORTIOR TECHNOLOGY (SHANGHAI) CO LTD
  • EP4708663A1 patent drawingFigure 1
  • EP4708663A1 patent drawingFigure 2
  • EP4708663A1 patent drawingFigure 3

AI summary

Disclosed is a method for controlling an induction motor, a device, an equipment and a storage medium. The method includes: determining an optimal starting frequency by acquiring initial equivalent circuit parameters of the induction motor at zero speed, and determining a starting voltage by a preset starting current, so as to enable the induction motor to enter a starting operation phase; then determining that the induction motor switches from the starting operation phase to the steady operation phase when it is determined that the motor starting speed of the induction motor in the starting operation phase is accelerated to be consistent with a preset steady operation speed; and using the optimal frequency with the updated equivalent parameters identified with the operation current and voltage values, and adjusting the drive voltage to maintain the motor speed to the required one.