Open-Winding Motor Startup Control to Eliminate Zero-Axis Current
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Solution Overview
Problem
Open-winding motors experience increased motor loss due to zero-axis currents during startup, which are not contributing to the motor's drive and occur when DC exciting currents flow through the phase windings.
Innovation Solution
A motor drive apparatus that includes a controller to manage the flow of DC exciting currents, ensuring zero-axis currents in each phase winding are minimized by strategically controlling the switching of inverters during startup, thereby reducing motor loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If DC exciting currents are supplied to phase windings for initial positioning during startup, then the rotor can be positioned at the initial rotational position, but zero-axis current increases causing increased motor loss
Solution Approach 1:
The patent extracts and eliminates the harmful zero-axis current component from the DC exciting current by controlling the electrification of both ends of each phase winding through two separate inverters, allowing only the useful current components to flow while preventing the zero-axis current that causes motor loss
Solution Approach 2:
The patent changes the control parameters by independently controlling the voltage applied to each end of the phase windings through separate inverter control, enabling precise control of current flow pathways to eliminate zero-axis current while maintaining positioning accuracy
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 solution effectively reduces motor loss by eliminating zero-axis currents during startup, enhancing motor efficiency and reducing energy wastage.
Implementation Method 1
a first inverter configured to control electrification to one end of each phase winding of the motor, and second inverter configured to control electrification to the other one of each phase winding of the motor, and drives the motor by switching of these first and second inverters
Implementation Method 2
currents flowing through the windings are detected, rotational speed of the rotor and rotor rotational position are detected or estimated on the basis of the detected currents
Data Source
AI summary
According to one embodiment, a motor drive apparatus includes a first inverter, a second inverter, and a controller. This controller rotationally moves, at the time of startup of a motor, a rotor of the motor to an initial position by DC excitation of supplying DC exciting currents from the first and second inverters to the phase windings of the motor and, after this rotational movement, PWM-controls switching of the first and second inverters in such a manner that a rotational speed of the rotor becomes a target rotational speed. Then, the controller carries out the DC excitation fey which a zero-axis current in each of the phase windings becomes approximately zero.