Slot-Less Rotating Electric Machine for High-Speed Current Control
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Solution Overview
Problem
Rotating electric machines with a slot-less structure face challenges in controlling electric current at high speeds due to low d-axis inductance, leading to a lack of overlapping regions for current control, resulting in inadequate performance.
Innovation Solution
The design includes a configuration where the number of electrical conductor sections per phase and poles is optimized to ensure the center of the voltage limit ellipse is outside the electric-current limit circle at maximum rotational speed, and the q-axis inductance is minimized to improve power factor and torque.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a slot-less structure is adopted to minimize q-axis inductance and improve power factor, then power factor and torque are improved, but d-axis inductance becomes low causing the voltage limit ellipse center to move away from the origin in the negative d-axis direction, making current control impossible at high speeds
Solution Approach 1:
The patent changes the electrical parameter configuration by optimizing the number of conductor sections per phase and pole, and adjusting the product of turns per phase and pole pairs. This parameter optimization shifts the voltage limit ellipse position in the d-q coordinate system, ensuring the positive-d-axis-side vertex intersects with the current limit circle while maintaining the slot-less structure benefits.
2Ease of operation
If the number of conductor sections per phase and pole is increased to move the voltage limit ellipse center closer to the origin, then current control capability is improved, but device complexity increases
Solution Approach 1:
The patent applies partial action by optimizing the conductor sections to the minimum necessary amount required to achieve the desired voltage limit ellipse position. Instead of increasing conductor sections excessively, the patent finds the optimal configuration where the product of turns per phase and pole pairs achieves the required performance with minimal complexity.
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 configuration allows for effective current control and high output even at high speeds by ensuring overlapping regions for current control and minimizing q-axis inductance, thereby enhancing power factor and torque.
Implementation Method 1
a magnet section having a plurality of magnetic poles whose polarities alternate in a circumferential direction
Implementation Method 2
the induced voltage in the armature coil has a certain value
Data Source
AI summary
A voltage limit ellipse is defined in a d-q coordinate system of a rotating electric machine by d-axis and q-axis currents flowing through an armature coil when the magnitude of a voltage vector applied to the armature coil is equal to a voltage limit value. The product of the number of electrical conductor sections per pole in each phase and the number of poles of the rotating electric machine is set to have, when the rotational speed of the rotating electric machine is equal to a maximum rotational speed, the center of the voltage limit ellipse located outside an electric-current limit circle and in a negative d-axis region in the d-q coordinate system and a positive-d-axis-side vertex of the voltage limit ellipse located inside or on the electric-current limit circle.