Induction Motor Power Converter Phase Synchronization at High Speed
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Solution Overview
Problem
Existing power conversion systems for induction motors face challenges in synchronizing rotating magnetic fields as the rotational speed increases, leading to difficulties in accurately receiving phase information and maintaining reliable synchronization of magnetic fields.
Innovation Solution
The system employs a power conversion device with a master and slave configuration, where the slave device corrects its phase based on the master voltage command to synchronize with the master rotating coordinate system, using bidirectional switches and phase correction units to maintain synchronization even at high rotational speeds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the rotational speed of the induction motor is increased, then the productivity is improved, but the synchronization accuracy of the rotating magnetic fields deteriorates due to phase information reception difficulties
Solution Approach 1:
The patent introduces an intermediary calculation process where the slave power conversion device calculates the rotation phase of its rotating coordinate system based on the command phase difference between master and slave devices. This intermediary calculation allows the slave device to synchronize with the master device's rotating magnetic field without directly receiving high-speed phase information, thereby resolving the contradiction between high rotational speed and phase accuracy.
2Power
If multiple power conversion devices are used to drive the induction motor, then the power output is increased, but the synchronization reliability of the rotating magnetic fields deteriorates
Solution Approach 1:
The patent implements a feedback mechanism where the slave power conversion device receives the master command phase from the master device, calculates the command phase difference, and adjusts its rotation phase accordingly. This feedback loop ensures that multiple power conversion devices maintain synchronized rotating magnetic fields, resolving the contradiction between increased power output and synchronization reliability.
3Productivity
If the rotational speed is increased, then the productivity is improved, but the device complexity increases due to the need for phase correction mechanisms
Solution Approach 1:
The slave power conversion device performs self-correction of its rotation phase by autonomously calculating the command phase difference and adjusting its own rotating coordinate system accordingly. This self-service approach eliminates the need for complex external phase correction mechanisms, thereby resolving the contradiction between high rotational speed and device complexity.
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 ensures reliable synchronization of rotating magnetic fields, maintaining torque generation efficiency and reducing the impact of increasing rotational speeds on phase accuracy.
Implementation Method 1
power conversion circuitry configured to perform a power conversion for outputting a driving power to an induction motor
Data Source
AI summary
The power conversion device may include: power conversion circuitry configured to perform a power conversion for outputting a driving power to an induction motor; and control circuitry. The control circuitry may be configured to: receive a master command phase from a master power conversion device; generate a voltage command having a command phase in a rotating coordinate system based on a torque target value, wherein a rotating magnetic field for driving a rotor of the induction motor is generated to rotate with the rotating coordinate system; calculate a rotation phase of the rotating coordinate system based on a command phase difference between the master command phase and the command phase to reduce the command phase difference; and control the power conversion circuitry to output the driving power to the induction motor, in synchronization with the master power conversion device, based on the rotation phase and the voltage command.