Induction Motor Power Conversion 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 generated by multiple power conversion devices, particularly at high rotational speeds, due to interference and accuracy issues in phase coordination.
Innovation Solution
A power conversion device configuration that includes a master control circuit and a slave control circuit, where the slave control circuit corrects its phase based on the master voltage phase to synchronize the rotating magnetic fields, using bidirectional switches and phase correction units to maintain synchronization even at increased rotational speeds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If multiple power conversion devices are used to control induction motors, then torque generation capability is improved, but synchronization accuracy of rotating magnetic fields deteriorates at high rotational speeds
Solution Approach 1:
The slave control circuit receives voltage phase information from the master control circuit and continuously adjusts its output phase to follow the master's phase characteristics. This feedback mechanism ensures that the rotating magnetic fields generated by multiple power conversion devices remain synchronized even at high rotational speeds, resolving the contradiction between improved torque capability and maintained synchronization accuracy.
Solution Approach 2:
The patent introduces an intermediate control layer where the master control circuit generates reference voltage phase information that serves as a mediator for the slave control circuit. This intermediary signal allows the slave device to synchronize its rotating magnetic field without direct interference, enabling multiple devices to work together with high torque capability while maintaining precise synchronization through the mediating phase information.
2Measurement precision
If phase coordination is tightened to prevent interference, then synchronization accuracy is improved, but system complexity increases
Solution Approach 1:
The patent merges the phase control functionality into the voltage command generation process of the master control circuit. Instead of adding separate complex synchronization control systems, the master circuit incorporates phase information that naturally guides the slave circuit's operation. This merging approach achieves high synchronization accuracy while avoiding excessive system complexity by integrating control functions rather than adding separate systems.
3Productivity
If rotational speed is increased to improve productivity, then output performance is improved, but phase coordination accuracy deteriorates
Solution Approach 1:
The system dynamically adjusts the phase coordination mechanism based on rotational speed. The master control circuit continuously provides updated voltage phase information that adapts to changing operational conditions. This dynamic approach allows the system to maintain accurate phase coordination across a wide range of rotational speeds, enabling high productivity while preventing the deterioration of synchronization accuracy that would otherwise occur at higher speeds.
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 configuration ensures high reliability in synchronizing rotating magnetic fields, effectively preventing interference and maintaining accurate phase coordination across varying rotational speeds, thus enhancing torque generation efficiency.
Implementation Method 1
a power conversion circuit (10B) that converts a primary side power into a secondary side power
Implementation Method 2
an induction motor having a first group of primary coils (51, 52, 53) that generate a first rotating magnetic field
Data Source
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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.