Multi-Winding Motor Charging With Zero-Torque Transformer Control
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Solution Overview
Problem
Existing energy transfer systems in vehicles, particularly electric and hybrid vehicles, face inefficiencies in power transfer between battery systems and external energy storage systems, as they require complex components and high current magnitudes for charging, which can lead to power loss and increased system complexity.
Innovation Solution
A multi-winding electric machine with a first and second set of windings connected to respective inverters, controlled by a controller to operate as a transformer during zero-torque conditions, allowing symmetric current vectors for efficient power transfer, utilizing a reference charging current value derived from optimal d-axis and q-axis currents to minimize current magnitude and maximize power transfer capability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If traditional single-winding motor structure is used for power transfer, then device complexity is reduced, but power transfer efficiency decreases and higher current magnitudes are required
Solution Approach 1:
The motor is divided into two independent winding sets (first and second windings) that can be controlled separately. Each winding can be independently managed to optimize power transfer efficiency, allowing the system to function as a transformer during charging mode while maintaining motor functionality during propulsion mode
Solution Approach 2:
The multi-winding motor serves dual functions: it operates as a motor during propulsion mode and as a transformer during charging mode. This eliminates the need for separate dedicated charging hardware, reducing overall system complexity while improving power transfer efficiency
2Power
If higher current magnitudes are used for charging, then charging power is increased, but power loss and system complexity increase
Solution Approach 1:
The system changes operational parameters by controlling current vectors in the d-q reference frame. By optimizing the relationship between d-axis and q-axis currents and maintaining symmetric current vectors about the d-axis, the system achieves efficient power transfer at lower current magnitudes, reducing I²R losses while maintaining required charging power
3Productivity
If multi-winding motor with symmetric current vector control is used, then power transfer efficiency is improved, but control complexity increases
Solution Approach 1:
The controller continuously monitors and adjusts the current vectors in the d-q reference frame, maintaining symmetric relationships about the d-axis. This feedback control ensures optimal power transfer efficiency while managing the complexity through systematic control algorithms that coordinate both winding sets
4Ease of operation
If traditional charging module is used, then system simplicity is maintained, but charging efficiency and power transfer capability are limited
Solution Approach 1:
The charging functionality is merged with the existing multi-winding motor structure. By utilizing the second winding set and controlling current vectors symmetrically, the motor itself performs power transfer functions, eliminating or simplifying the need for separate on-board charging modules while achieving superior charging efficiency
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 solution enables efficient energy transfer by reducing the magnitude of charging current needed, increasing charging efficiency, and simplifying vehicle systems by potentially eliminating components like on-board charging modules, while maintaining or exceeding existing charging efficiency standards.
Implementation Method 1
the multi-winding motor functions as a transformer. The control of the first inverter and the second inverter provides for power transfer between the first set of windings and the second set of windings
Data Source
AI summary
An energy transfer system of a vehicle includes a multi-winding motor, a first inverter connected to a first set of windings, and a second inverter connected to a second set of windings. The system includes a controller configured to control the first inverter and the second inverter to control a charging current through the multi-winding motor at a desired power when the multi-winding motor is in a zero-torque condition. The controller is configured to control the charging current through the first inverter and second inverter so that a first current vector associated with the first set of windings and a second vector associated with the second set of windings are symmetric about a d-axis and the multi-winding motor functions as a transformer, the control of the first inverter and the second inverter providing for power transfer between the first set of windings and the second set of windings.