Rotating Transformer Excitation for Brushless Magnet-Less Synchronous Machines
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Solution Overview
Problem
Current electric vehicle motors, such as asynchronous motors and permanent magnet synchronous motors, face inefficiencies, bulkiness, and sustainability issues due to the use of slip rings and rare earth minerals, necessitating a magnet-less and brush-less solution for improved power density and reduced environmental impact.
Innovation Solution
A magnet-less and brush-less rotating transformer excited synchronous machine design featuring a main rotor with DC field windings and an AC poly-phase distributed stator, utilizing a rotating transformer to convert AC current to DC for excitation, eliminating the need for permanent magnets and slip rings, and incorporating a three-phase rectifier for energy transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If asynchronous motors use slip rings to transfer power to rotor field windings, then power transfer is achieved, but the motor becomes bulky and less efficient with increased copper losses
Solution Approach 1:
The patent replaces the mechanical slip ring system with a magnetic coupling system. The rotor field windings are excited through magnetic induction from the stator, eliminating the need for physical electrical contacts. This substitution removes copper losses associated with slip rings while maintaining power transfer capability through electromagnetic coupling.
2Power
If asynchronous motors use slip rings for power transfer, then rotor excitation is achieved, but the motor requires frequent maintenance due to wear and tear
Solution Approach 1:
The patent eliminates mechanical slip rings by using magnetic coupling for rotor excitation. Without mechanical contacts subject to friction and wear, the system achieves significantly improved reliability and reduced maintenance requirements while maintaining the ability to provide rotor field excitation.
3Loss of energy
If permanent magnet synchronous motors use permanent magnets, then efficiency is improved, but environmental and geopolitical sustainability issues arise
Solution Approach 1:
The patent extracts and removes permanent magnets from the motor design. Instead of using rare earth permanent magnets that cause environmental harm during mining and manufacturing, the system uses electromagnets with DC field windings on the rotor, excited through magnetic coupling from the stator, achieving similar efficiency without the environmental burden.
Solution Approach 2:
The patent changes the fundamental operating parameter of the rotor from permanent magnetic fields to electromagnetic fields. By using controllable DC field windings instead of fixed permanent magnets, the system achieves comparable efficiency while eliminating dependence on rare earth minerals and their associated environmental issues.
4Power
If permanent magnet synchronous motors use permanent magnets, then torque-speed characteristic is improved, but geopolitical dependency increases due to rare earth mineral dominance
Solution Approach 1:
The patent removes permanent magnets containing rare earth minerals from the design. By using DC field windings on the rotor that are electromagnetically coupled from the stator, the system maintains excellent torque-speed characteristics while eliminating geopolitical vulnerability associated with rare earth mineral supply chains.
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 achieves a cost-effective, compact, and long-lasting synchronous machine with reduced wear and tear, enabling full speed range sensor-less control and rotor temperature sensor-less detection, while being environmentally friendly and efficient across various operating conditions.
Implementation Method 1
The RT rotor may include the AC poly-phase distributed winding and a second predefined number of poles. Further, the RT stator may be co-axially assembled over the RT rotor and may include the AC poly-phase distributed winding.
Implementation Method 2
The synchronous machine may include a three-phase rectifier which may be configured to convert an AC current from the RT rotor to a DC current and transmits the DC current to the DC field windings of the main rotor
Implementation Method 3
The main stator of the main motor may be co-axially assembled over the main rotor and mechanically supported by the housing. Further, the main stator may include an electrically coupled Alternating Current (AC) poly-phase distributed windings and a first predefined number of poles.
Implementation Method 4
The synchronous machine may further include a ball bearing coupled to the first end of the shaft
Data Source
AI summary
A synchronous machine (100) includes a housing, a shaft (106) to mount a three-phase rectifier (124), main motor (116) and a rotating transformer (RT) (108). The main rotor (110) is concentrically and co-axially mounted on shaft (106), and main stator (112) is concentrically and co-axially assembled over main rotor (110). Main rotor (110) includes Direct Current field windings and main stator (112) includes Alternating Current poly-phased distributed windings. Further, the RT (108) includes an RT rotor (120) and RT stator (122). RT rotor (120) and RT stator (122) may include AC poly-phase distributed windings and second predefined number of poles. Further, RT rotor (120) may be configured to be rotatably coupled on first end (106A) of shaft (106). The RT stator (122) may be configured to concentrically and co-axially assembled over RT rotor (120).