Inductive Rotary Transformer for Synchronous Machine Rotor
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Solution Overview
Problem
Existing synchronous machines lack improved control properties and efficiency, particularly in high-speed operations and power management, with limitations in wear-free supply of field windings and rapid excitation control.
Innovation Solution
The design features coil windings on the rotor supplied by an inductive rotary transformer with a controller unit and sensors for current and temperature regulation, enabling direct control of excitation current and torque, and using an active rectifier for unipolar current supply, which allows for efficient energy transmission and reduced losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If coil windings are supplied via traditional sliding contacts or commutators, then electrical connection is established, but wear and maintenance issues occur
Solution Approach 1:
The patent replaces mechanical electrical connections (sliding contacts, commutators) with an inductive rotary transformer system. The stationary primary winding and rotating secondary winding establish electrical connection through magnetic coupling across the air gap, eliminating mechanical wear while transmitting power to the rotor coil windings
Solution Approach 2:
The inductive rotary transformer acts as an intermediary between the stationary power supply and the rotating coil windings. The magnetic field in the air gap serves as the medium for energy transfer, enabling wear-free power transmission to the rotating part
2Ease of operation
If excitation current is controlled from the primary side, then control is simplified, but control dynamics are reduced
Solution Approach 1:
The controller unit on the rotor receives feedback from sensors detecting current through the coil windings and rotor temperature. This feedback enables the controller to regulate excitation current dynamically by controlling the active rectifier, achieving both simplicity and fast response through closed-loop control
3Weight of moving object
If passive rectifier is used on the rotor, then moment of inertia is kept low, but control capability is limited
Solution Approach 1:
The patent uses an active rectifier with controllable power switches instead of a passive rectifier. This enables dynamic control of the rectified current waveform, allowing precise regulation of excitation current while managing the increased moment of inertia through efficient switching control
4Loss of energy
If resonance circuit is added to the secondary winding, then efficiency is improved with distance fluctuations, but device complexity increases
Solution Approach 1:
The patent connects a capacitance in series or parallel with the secondary winding to create a resonance circuit. This tunes the secondary side to resonate at the operating frequency, compensating for variations in air gap distance and maintaining high energy transmission efficiency despite the added 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 solution enables high-speed operation up to 100,000 revolutions per minute with reduced no-load losses, efficient power management, and precise control of torque and excitation, optimizing power consumption and output performance.
Implementation Method 1
coil windings, in particular as excitation coils, are arranged on the rotor, with the coil windings being supplied with electricity by means of an inductive rotary transformer whose secondary winding is connected to the rotor and whose primary winding is inductively coupled to the secondary winding
Implementation Method 2
such a capacitance is connected in series or in parallel that the associated resonant frequency essentially corresponds to the frequency of the current fed into the primary winding
Data Source
Figure 1
Figure 2
AI summary
Separately excited electrical synchronous machine and method for operating a synchronous machine, wherein coil windings, in particular in the form of field coils, are arranged on the rotor, wherein the coil windings are electrically supplied by means of an inductive rotary transformer, the secondary winding of which is connected to the rotor and the primary winding of which is arranged in a stationary manner, in particular is connected to the stator of the synchronous machine, said primary winding being inductively coupled to the secondary winding.