Three-Phase Inverter Control for Single-Phase Motor Platform Positioning
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Solution Overview
Problem
Controlling three single-phase motors acting in a common direction to move a platform precisely in a normal direction is challenging due to uneven distribution and non-identical motor constants, leading to potential tilting and uncontrollability, especially when the force application area is not aligned with the position measuring device.
Innovation Solution
A method using a three-phase inverter to operate the motors, where one motor is driven between two phases and the other two motors are connected in series or parallel between the remaining phases, allowing for adjustment of the force application area to ensure stable and cost-effective control by parameterizing the current distribution to maintain total force centrality and controllability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If three single-phase motors are controlled independently with separate control circuits, then each motor can be precisely controlled, but the control structure becomes complex and costly
Solution Approach 1:
The patent combines three separate control circuits into a single control circuit that manages all three single-phase motors. This is achieved by using a three-phase inverter where the motors are connected to different phase combinations, allowing centralized control while maintaining individual motor control capability. The merging reduces system complexity and cost while preserving positioning precision through coordinated phase control.
Solution Approach 2:
The three-phase inverter is designed to serve multiple functions: it controls all three single-phase motors simultaneously while providing independent control capability for each motor through different phase combinations. This multi-functional approach allows a single device to replace what would traditionally require three separate control circuits, reducing overall system complexity.
2Ease of operation
If the force application area of the motors is not aligned with the position measuring device, then the motors can be distributed evenly around the platform, but the platform may tilt and become uncontrollable
Solution Approach 1:
The patent applies different control strategies to different motors based on their local positions relative to the position measuring device. By adjusting the force distribution locally at each motor while maintaining even physical distribution around the platform, the system achieves both operational flexibility and stability. The control circuit compensates for positional differences to ensure the force application area aligns with the measuring device.
Solution Approach 2:
The system dynamically adjusts control parameters (current distribution, phase timing) to shift the effective force application area to align with the position measuring device. This parameter adjustment allows the platform to maintain stability even when motors are evenly distributed, as the control parameters compensate for any misalignment between force application and measurement points.
3Ease of manufacture
If a conventional three-phase converter is used to control three single-phase motors, then cost is reduced, but control adaptability must be optimized
Solution Approach 1:
The patent optimizes control parameters (switching frequencies, phase angles, current distribution) to adapt the conventional three-phase converter for controlling single-phase motors. By adjusting these parameters, the system maintains cost-effectiveness using standard hardware while achieving the adaptability needed for precise positioning control of single-phase motors.
Solution Approach 2:
The system incorporates feedback from the position measuring device to continuously adjust control parameters of the three-phase inverter. This feedback mechanism enables the conventional converter to adapt to the specific requirements of single-phase motors, optimizing performance while maintaining cost-effectiveness. The feedback loop ensures proper synchronization and force distribution despite using standard hardware.
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 simplifies the control structure, maintains stable positioning, and ensures controllability by shifting the force application area to align with the tilting axis, allowing precise movement without tilting, even under conditions of motor misalignment and non-uniform motor constants.
Implementation Method 1
Voice coil motors, for example, each made up of a coil in a permanent magnetic field, are suitable. The magnetic field and coil axis are parallel to the Z-direction, so that when a current flows through the coil, a force proportional to the current is generated in this direction.
Data Source
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AI summary
A method is described for controlling three single-phase motors (M1, M2, M3) and moving a platform (P) in a normal direction (Z), wherein the motors (M1, M2, M3) are controlled by a three-phase inverter (U), such that a first motor (M1) is operated between a first phase (VA) and a second phase (VB) of the inverter (U), and a series or parallel connection of a second and third motor (M2, M3) is operated between a second phase (VB) and a third phase (VC) of the inverter (U). A platform suitable for carrying out this method is also disclosed.