Brushless Synchronous Machine Third Harmonic Excitation
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Solution Overview
Problem
Synchronous machines using brushes and slip rings face reliability and maintenance issues due to mechanical failures, while those using permanent magnets are becoming expensive due to material scarcity.
Innovation Solution
A brushless synchronous motor design incorporating a stator with multiple windings and a rotor with third harmonic coils, utilizing a drive circuit to generate alternating and direct current components, which induce a voltage in the rotor windings to create a rotating magnetic field without brushes or slip rings, and a diode bridge to rectify the voltage for rotor rotation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If brushes and slip rings are used to excite the field winding, then the synchronous machine can operate, but reliability deteriorates due to mechanical failure
Solution Approach 1:
The patent extracts and eliminates the brushes and slip rings from the synchronous machine structure. By using a brushless excitation system with a rotating rectifier bridge mounted on the rotor, the field winding is excited through induced voltage from stator windings rather than through mechanical contact, thereby removing the reliability-critical components while maintaining the excitation function
Solution Approach 2:
The patent replaces the mechanical contact-based excitation system (brushes and slip rings) with an electromagnetic induction-based system. The stator windings generate a rotating magnetic field that induces voltage in rotor windings, which is then rectified and applied to the field winding, substituting mechanical energy transfer with electromagnetic energy transfer
2Reliability
If permanent magnets are used in the rotor, then the synchronous machine can operate without brushes, but cost increases due to material scarcity
Solution Approach 1:
The patent changes the excitation method from permanent magnets to electromagnetic induction with rectified output. Instead of using expensive permanent magnet materials, the system uses standard copper windings on the stator that induce voltage in rotor windings, which is then rectified to provide DC excitation, achieving the same brushless operation at lower material cost
3Ease of operation
If brushes and slip rings are used, then the field winding can be excited, but maintenance requirements increase due to mechanical wear
Solution Approach 1:
The patent removes the maintenance-prone brushes and slip rings from the system by implementing a brushless excitation scheme. The rotating rectifier bridge is mounted directly on the rotor and receives power through induction from stator windings, eliminating the need for sliding contacts and their associated wear and maintenance requirements
Solution Approach 2:
The patent substitutes the mechanical contact system with an electromagnetic field-based system. The rotating magnetic field from stator windings induces voltage in rotor windings without mechanical contact, and the rectified voltage provides field excitation, replacing the mechanical wear-based system with a wear-free electromagnetic system
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
The solution enhances the reliability and reduces maintenance costs by eliminating mechanical failures associated with brushes and slip rings, while avoiding the rising costs of permanent magnets, providing efficient and cost-effective operation of synchronous motors.
Implementation Method 1
The generated square waves induce a voltage in the first rotor winding
Implementation Method 2
The diode bridge is mounted to the rotor to rectify the voltage induced in the first rotor winding and to apply the resulting DC voltage to the second rotor winding
Data Source
AI summary
A brushless, synchronous machine is provided. A brushless, synchronous motor includes a rotor, a stator extending around at least a portion of the rotor and separated from the rotor by an air gap, a first stator winding, a second stator winding, a third stator winding, a drive circuit, a first rotor winding, a second rotor winding, and a diode bridge. The first stator winding, the second stator winding, and the third stator winding are mounted to the stator to generate square waves. The drive circuit is configured to provide a current to the first stator winding, the second stator winding, and the third stator winding, wherein the current includes an alternating current (AC) component and a direct current (DC) component. The first rotor winding is mounted to the rotor to form a plurality of third harmonic coils. The second rotor winding is mounted to the rotor. The generated square waves induce a voltage in the first rotor winding that is applied to the second rotor winding to create a brushless, synchronous motor. The diode bridge is mounted to the rotor to rectify the voltage induced in the first rotor winding and to apply the resulting DC voltage to the second rotor winding.