Permanent-Magnet Rotary Machine Geometry for Low-Load PWM Efficiency
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Solution Overview
Problem
Existing rotary electric machines experience increased energy losses and reduced efficiency at low load when using a full-wave control strategy, leading to higher electrical consumption in motor mode and reduced energy generation in generator mode.
Innovation Solution
The rotary electric machine is designed with specific geometric ratios and magnetic pole configurations, including buried permanent magnets with radial magnetization, to optimize efficiency across varying rotational speeds using pulse-width modulation and full-wave control strategies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If full-wave control strategy is used, then inverter efficiency is improved, but electrical consumption increases in motor mode
Solution Approach 1:
The optimized geometric parameters of the rotary electric machine enable it to maintain high efficiency under full-wave control strategy, thereby reducing overall electrical consumption in motor mode while keeping inverter losses low
2Loss of energy
If full-wave control strategy is used, then inverter efficiency is improved, but energy generation is reduced in generator mode
Solution Approach 1:
The patent optimizes the geometric ratios (first ratio ≥0.40 and <0.7, second ratio ≥0.8 and ≤1.5) to enable the rotary electric machine to maintain high efficiency under full-wave control strategy, thereby maximizing energy generation in generator mode while minimizing inverter losses
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 reduces energy losses at low load and enhances overall efficiency, reducing electrical consumption in motor mode and increasing energy generation in generator mode.
Implementation Method 1
a rotor (3) inscribed in a cylinder of revolution having for axis the axis of rotation (A) and having an external radius (L), and comprising: a rotor body (24), in particular a second stack of magnetic laminations, comprising cavities (38), permanent magnets (29, 30) arranged inside the cavities (38) so as to form a succession of north magnetic poles (25) and south magnetic poles (26)
Implementation Method 2
a first magnetic material of the stator body (9), in particular the first stack of magnetic laminations, and a first magnetic material of the rotor (3), in particular the second stack of magnetic laminations or one of the permanent magnets
Data Source
AI summary
A rotary electric machine includes a stator including a stator body and a winding, the winding passing through slots of the stator body, the slots having an isthmus. A rotor includes a rotor body with cavities and permanent magnets, arranged in the cavities, forming magnetic poles having a central axis, a quadrature axis being equidistant from two successive central axes. The ratio between the width of the isthmus and the width of the slot being greater than or equal to 0.40 and less than or equal to 0.7, and the ratio between an air gap at the central axis and an air gap at the quadrature axis being greater than or equal to 0.8 and less than or equal to 1.5. An electrical assembly includes such a rotary electric machine and an inverter.