Synchronous Motor Torque Control via Reactive Current Correction
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Solution Overview
Problem
Existing synchronous electric motor control systems with permanent magnets face challenges in energy efficiency and speed control accuracy, particularly at low speeds, due to torque pulsations and complex computational requirements, and are limited by the use of sensor-based and sensorless methods that are ineffective at low speeds and inefficient in energy usage.
Innovation Solution
The method involves determining changes in Iq reactive current to generate correction signals for Ud and Uq voltage, using a proportional-integral controller to optimize voltage settings and minimize calculations, allowing for direct control of the electric motor torque without pulse-width modulation, thereby improving energy efficiency and control speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If sensorless control based on back EMF tracking is used, then the system complexity is reduced, but the measurement precision deteriorates at low speeds
Solution Approach 1:
The patent introduces an intermediary observer unit that processes stator currents and voltages to estimate rotor position and speed. This mediator enables sensorless operation by deriving position information from electrical measurements rather than direct sensing, resolving the contradiction between reduced complexity and maintained precision at low speeds through advanced signal processing algorithms.
Solution Approach 2:
The control system dynamically adjusts control parameters including voltage magnitude, frequency, and observer gains based on operating conditions. By changing parameters adaptively, the system maintains measurement precision across the full speed range while keeping the device structure simple, particularly improving low-speed performance through parameter optimization.
2Power
If direct torque control is implemented, then the electromagnetic torque at low speeds is improved, but the device complexity increases due to significant computational operations
Solution Approach 1:
The control algorithm is segmented into discrete computational steps including current measurement, coordinate transformation, torque calculation, and voltage vector selection. This segmentation allows the complex DTC computations to be organized efficiently, reducing processing burden while maintaining high electromagnetic torque output at low speeds through structured calculation sequences.
Solution Approach 2:
The system applies partial computational effort by selecting from predefined voltage vectors and switching states rather than calculating optimal continuous control. This discrete approach provides sufficient torque control performance without requiring full computational resources, balancing torque output with processing complexity.
3Loss of energy
If pulse-width modulation is avoided for direct voltage control, then the energy efficiency is improved, but the manufacturing precision deteriorates due to voltage ripple
Solution Approach 1:
The system employs periodic voltage switching at the inverter level to achieve average voltage control without PWM. By rapidly switching between discrete voltage states in a periodic manner, the system achieves effective voltage regulation and reduces energy losses associated with PWM while minimizing ripple effects through appropriate switching frequency selection.
Solution Approach 2:
The inverter operates in a universal switching mode that combines voltage control and current control functions without requiring separate PWM modulation stages. This multi-functional operation simplifies the control architecture, improves energy efficiency by eliminating redundant modulation, and maintains adequate voltage precision through direct switching control.
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 enhances the accuracy of torque control and energy efficiency of the synchronous electric motor, increasing operational speed and reducing computational complexity while maintaining optimal control across a wide frequency range.
Implementation Method 1
synchronous electric motor with permanent magnets
Implementation Method 2
interaction between stator winding magnetic field and rotor magnetic field
Implementation Method 3
tracking a back electromotive force during a rotation of the motor
Data Source
AI summary
An invention relates to synchronous electric motors, in particular, to a method of controlling a synchronous electric motor with permanent magnets, utilized as a linear drive for an electric submersible pump unit. A technical result achieved from a method embodiment consists in increasing an accuracy of a torque control of the electric motor and improving an energy efficiency of the electric motor, as well as in achieving an increase in an operation speed of control systems by minimizing settings and eliminating complex calculations of motor parameters. An essence of the claimed method consists in an implementation of an algorithm of the control system of the synchronous electric motor with permanent magnets, utilized, in particular, as a linear drive for an electric submersible pump unit.