Brushless Wound Field Synchronous Machine With Pulsed Rotor Excitation
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Solution Overview
Problem
Wound field synchronous machines face inefficiencies due to varying operational loads, and conventional methods using brushes for rotor excitation lead to mechanical friction and wear, reducing overall efficiency.
Innovation Solution
The implementation of a power converter system with a transformer and energy storage components allows for pulsed control of the rotor winding, optimizing magnetic field control and reducing energy wastage by managing back EMF.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If brushes are used for rotor excitation, then mechanical contact is established for power transmission, but mechanical friction and wear increase reducing efficiency
Solution Approach 1:
The patent replaces the mechanical brush-contact system with a brushless excitation system using a transformer and rectifier. The transformer couples the stator circuit to the rotor circuit magnetically, eliminating the need for physical brushes and slip rings. This substitution removes mechanical friction and wear while maintaining electrical power transmission to the rotor winding.
Solution Approach 2:
The patent introduces a transformer as an intermediary device between the stator and rotor circuits. The transformer provides magnetic coupling to transfer excitation power to the rotor without direct electrical contact, serving as a mediator that eliminates harmful mechanical contact while enabling energy transfer.
2Reliability
If continuous excitation is provided to rotor winding, then magnetic field is maintained, but energy wastage increases due to back EMF
Solution Approach 1:
The patent implements periodic pulsing of the rotor excitation instead of continuous excitation. The controller periodically switches the excitation on and off, creating pulsed magnetic fields that maintain average field strength while reducing energy losses from continuous back EMF generation. This periodic action reduces energy wastage while maintaining sufficient magnetic field stability for machine operation.
Solution Approach 2:
The patent changes the excitation parameter from continuous DC to pulsed DC with variable duty cycle. By controlling the pulse width and frequency, the system optimizes the average magnetic field strength while minimizing energy losses. The variable excitation level adapts to different operating conditions, reducing energy wastage during partial load operation.
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 approach enhances energy conversion efficiency by optimizing magnetic field control and reducing mechanical friction, thereby improving operational efficiency across varying load conditions.
Implementation Method 1
A transformer comprises at least one magnetic coupling
Implementation Method 2
a rectifier electrically connected across the secondary winding
Implementation Method 3
an energy storage arranged to store energy provided by the rectifier and the rotor winding and provide a voltage to the rotor winding in a second direction opposite the first direction when the switch switches off voltage
Implementation Method 4
When a machine is operating as a motor, it converts electrical energy into mechanical energy. When operating as a generator, the machine converts mechanical energy into electrical energy.
Data Source
AI summary
An electric machine is provided. A transformer comprises a magnetic coupling. A wound field synchronous machine comprises a rotor winding, a secondary circuit of the transformer electrically connected to the rotor winding, and a stator winding. The secondary circuit comprises a secondary winding, a rectifier electrically, a switch for switching voltage between the rotor winding and the rectifier in a first direction, and an energy storage arranged to store energy provided by the rectifier and the rotor winding and provide a voltage to the rotor winding in a second direction. A power converter is coupled between the power supply and the wound field synchronous machine. The power converter comprises a stator winding power supply arranged to provide multiple phase AC excitation to the stator winding and a primary circuit of the transformer comprising a primary winding arranged to provide AC power to the primary winding.