Motor Control System Voltage Stability via Phase Feedback
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Solution Overview
Problem
In motor control systems with multiple alternating-current motors connected to a single converter via inverters, feedback controls can interfere with each other, leading to unstable and stepwise system voltage control, making smooth variable control challenging.
Innovation Solution
A motor control system that includes a converter and two inverters, with a control unit capable of executing sinusoidal PWM, overmodulation, and rectangular wave control, using feedback of the current phase or voltage phase to select the optimal control method for each motor, thereby preventing interference and ensuring stable system voltage control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If feedback control is applied to each motor independently to minimize individual motor losses, then motor efficiency is improved, but feedback controls interfere with each other causing system voltage instability
Solution Approach 1:
The patent merges the feedback control of multiple motors into a unified control system. Instead of applying independent feedback control to each motor, the invention combines the feedback mechanisms to operate as a single coordinated system, thereby preventing interference between controls while maintaining system voltage stability.
Solution Approach 2:
The control system is designed to serve multiple motors simultaneously with a single feedback control mechanism. The universal controller can adapt to different motor requirements and operating conditions, providing stable system voltage control while minimizing overall system losses through coordinated management of all motors.
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
The system achieves stable and smooth variable control of system voltage by selecting the optimal control method for each motor, reducing losses and minimizing interference between feedback controls, allowing for efficient operation across different torque and rotation speed conditions.
Implementation Method 1
a converter that is configured to be able to step up a direct-current voltage, supplied from a power supply
Implementation Method 2
first and second inverters, each of which is configured to convert a direct-current voltage, which is a system voltage output from the converter, to an alternating-current voltage
Implementation Method 3
first and second motors that are driven by the alternating-current voltages respectively applied from the first and second inverters
Data Source
AI summary
A motor control system includes: a converter; two inverters; two alternating-current motors; and a control unit. The control unit is configured to control the system voltage by feedback of a current phase of a current vector of motor current of each of the motors on a d-q coordinate plane so that rectangular wave control of at least one of the first and second motors is performed in a state where the current phase is an optimal current phase, wherein the control unit selects, as a subject of the feedback, the current phase of one of the motors that is larger than the other motor in system voltage deviation obtained based on the current vector.