Current Injection Mechanism for Brushless Synchronous Machine Excitation
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Solution Overview
Problem
Existing electromagnetic machine systems require a separate dedicated exciter to produce electrical current for rotor windings, which can fail or degrade, leading to compromised synchronous coupling between rotor and stator, especially in applications where reliability and efficiency are critical.
Innovation Solution
A current injection mechanism is coupled with the stator windings to inject secondary electrical currents, changing the stator magnetic field's flux distribution, which interacts with a rotor inductor to produce an electrical excitation current for the rotor windings, eliminating the need for a separate exciter and enhancing system resilience and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a separate dedicated exciter is used to produce electrical current for rotor windings, then the rotor can be electrically excited to produce a rotor magnetic field, but the system complexity increases and reliability decreases due to the additional component that can fail or degrade
Solution Approach 1:
The patent merges the excitation function into the existing stator windings by injecting secondary currents that modify the stator magnetic field flux distribution. The inductor on the rotor interacts with this modified field to generate excitation current, eliminating the need for a separate dedicated exciter component and thereby reducing system complexity while improving reliability.
Solution Approach 2:
The stator windings serve multiple functions: they produce the primary rotating magnetic field for motor operation and simultaneously generate modified flux distribution through injected secondary currents that induces excitation current in the rotor inductor. This multi-functionality eliminates the need for separate excitation components.
2Reliability
If a separate dedicated exciter is used to produce electrical current for rotor windings, then the rotor can be electrically excited, but the system requires additional components that increase the risk of failure and degradation
Solution Approach 1:
The excitation function is merged with the stator windings system, using the same physical structure to perform both motor operation and excitation generation. This eliminates separate exciter components that could fail or degrade, thereby improving system resilience while reducing component count.
3Reliability
If secondary electrical currents are injected into stator windings to change flux distribution, then excitation current is produced for rotor windings, but additional control complexity is introduced
Solution Approach 1:
The system uses the existing stator magnetic field and injected secondary currents to self-generate the excitation current needed for rotor windings through electromagnetic induction in the rotor inductor. This self-service mechanism ensures continuous electrical excitation without requiring complex external excitation control systems.
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 ensures continuous electrical excitation of rotor windings, maintaining synchronous operation even if the external exciter fails, and improves power transfer efficiency by using harmonic currents to optimize flux linkage, reducing asymmetry and current ripple.
Implementation Method 1
A current injection mechanism is coupled with windings of the stator and injects electrical currents into the stator so as to change a flux distribution of a magnetic field produced by the stator
Implementation Method 2
The rotor includes an inductor positioned to interact with the magnetic field when the flux distribution is changed, thereby producing an electrical excitation current for exciting the rotor windings
Data Source
AI summary
A electromagnetic machine system includes a rotor and a stator positioned about the rotor. A current injection mechanism is coupled with windings of the stator and structured to inject electrical currents therein so as to change a flux distribution of a magnetic field produced by the stator. The injected currents may be harmonic currents. The rotor further includes an inductor positioned to interact with the magnetic field when the flux distribution is changed, to produce an electrical excitation current for exciting windings in the rotor. The machine system may be a synchronous motor or generator, and may be brushless. Applications of the current injection strategy to direct torque control and vector control are also disclosed.