Variable-Pole Electric Motor With Switching Actuator
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Solution Overview
Problem
Existing electric motors face limitations in achieving high efficiency operation in both low-speed high-torque and high-speed low-torque regions due to constraints in field weakening control, which restricts their application range and power density.
Innovation Solution
The electric motor design incorporates a variable-pole structure with an excitation stator, salient-pole rotor, and excitation rotor, where the switching actuator selectively fixes their relative positions, allowing for adjustment of rotor pole number and operational frequency without changing the winding connection, enabling efficient operation across a wide range of speeds and torques.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If field weakening control is used to achieve high-speed operation, then the motor can operate at higher speeds, but the efficiency deteriorates and the operational range is limited
Solution Approach 1:
The patent applies dynamics by making the rotor pole number variable through a switching actuator that can selectively fix different relative positions between the excitation stator, salient-pole rotor, and excitation rotor. This allows the motor to dynamically adjust its pole pairs (e.g., switching between 4/6/8 pole pairs) to match different operational requirements, enabling high-speed operation without field weakening control and thus maintaining high efficiency across a wide speed range.
2Adaptability or versatility
If field weakening control is used to expand operational range, then the motor can cover both low-speed high-torque and high-speed low-torque regions, but the efficiency deteriorates in low-speed high-torque region
Solution Approach 1:
The switching actuator enables dynamic reconfiguration of the rotor structure by selectively fixing different combinations of the excitation stator, salient-pole rotor, and excitation rotor. This allows the motor to switch between different operational modes (e.g., single rotor mode for high-speed operation, dual rotor mode for low-speed high-torque operation) without energy loss, achieving both wide adaptability and high efficiency across all operational regions.
3Force
If the motor structure is designed for high torque output, then the torque density improves, but the device complexity increases
Solution Approach 1:
The patent employs nesting by placing the excitation rotor inside the salient-pole rotor, with both rotors sharing a common stator. The excitation rotor is positioned concentrically within the salient-pole rotor structure, creating a compact nested configuration. This nested design achieves high torque density without significantly increasing external dimensions or overall structural complexity, as the components are integrated in a space-efficient manner.
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 design enhances torque density and power density, expands the motor's application range, and allows for controlled adjustment between low-speed high-torque and high-speed low-torque regions, improving efficiency and performance.
Implementation Method 1
an excitation stator 10, a salient-pole rotor 20 and an excitation rotor 30
Implementation Method 2
a switching actuator configured to select at least one of the salient-pole rotor and the excitation rotor to serve as a rotor rotatable relative to the excitation stator by selectively fixing relative positions of two of the excitation stator, the salient-pole rotor and the excitation rotor
Data Source
AI summary
An electric motor (100) includes an excitation stator (10), a salient-pole rotor (20) and an excitation rotor (30), any two of the excitation stator (10), the salient-pole rotor (20) and the excitation rotor (30) being rotatable relative to each other; and a switching actuator (50) configured to select at least one of the salient-pole rotor (20) and the excitation rotor (30) to serve as a rotor rotatable relative to the excitation stator (10) by selectively fixing relative positions of two of the excitation stator (10), the salient-pole rotor (20) and the excitation rotor (30).