Switched Reluctance Machine Power Electronics Circuit
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Solution Overview
Problem
Switched Reluctance machines (SRM) face high costs due to expensive power electronics, particularly because they require multiple power switches and active control, making them less economically viable compared to other motor types like BLDC motors.
Innovation Solution
A power electronics circuit for SRM that uses a circulating current to reduce the power rating of switches, allowing for the use of full transistor bridges and passive components, eliminating the need for additional windings and active control, thereby reducing component count and cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional asymmetric H-bridge power electronics are used for SRM control, then the machine can operate with proper current control, but the system cost increases significantly due to expensive power switches and active control requirements
Solution Approach 1:
The SRM uses its own phase windings to generate the circulating current that provides the magnetic field, eliminating the need for separate excitation windings or permanent magnets. The machine serves its own magnetic field generation needs through the circulating current in the shared windings, reducing external control requirements and component costs
Solution Approach 2:
The phase windings serve dual functions: they generate the circulating current that creates the magnetic field and simultaneously act as the field windings. This multi-functionality eliminates the need for separate excitation systems, reducing the number of components and overall system cost while maintaining proper magnetic field generation for reliable operation
2Power
If multiple power switches and active control are used to maintain magnetic field, then the machine performance is improved, but the component count and system cost increase
Solution Approach 1:
The invention merges the function of separate field windings with the phase windings by using the same windings to carry both the circulating current (which generates the magnetic field) and the phase current. This consolidation reduces the number of separate components and simplifies the overall system architecture while maintaining full machine performance
Solution Approach 2:
The invention extracts and eliminates the need for separate excitation systems, permanent magnets, or additional field control circuitry by using the circulating current through phase windings to generate the necessary magnetic field. This removal of unnecessary components reduces system complexity and cost while preserving power output
3Measurement precision
If conventional SRM topology with separate field windings is used, then the magnetic field control is precise, but the manufacturing cost and system complexity increase
Solution Approach 1:
The SRM generates its own magnetic field using the circulating current through the phase windings, eliminating the need for separate field windings or permanent magnets. This self-sufficient approach simplifies manufacturing by reducing the number of components that need to be assembled and wired, while the circulating current provides sufficient magnetic field control precision for normal 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 solution enables SRM systems to operate efficiently with reduced power switch ratings, lower losses, and without the need for position sensors or controllers, making them more cost-effective and adaptable for various applications, including wind turbines and wheeled vehicles.
Implementation Method 1
A power electronics circuit is proposed for a switched reluctance machine. The circuit comprises a means for generating a circulating current in the ring. The circulating current generates a magnetic field that enables energy conversion from electrical to mechanical form
Implementation Method 2
The invention relates to the field of Switched Reluctance machines (SRM), in particular to a system comprising a Switched Reluctance Machine (SRM) such as a Switched Reluctance Motor or a Switched Reluctance Generator
Data Source
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AI summary
A generator or motor system for converting mechanical power into electrical power or vice versa, comprising: a switched reluctance machine having a rotor and a stator with a number of phase windings (A, B, C), the phase windings being partitioned in groups, each group comprising at least two phase windings connected in series to form a ring structure (R1); a power electronics circuit comprising: for each ring structure, an independently controllable means (V2) for generating a circulating current (I2) in said ring structure; a number of legs (Leg1), each of the legs comprising at least two diodes or switches connected in series between a first and a second voltage rail, each leg having an intermediate node (m1) located between the two diodes or switches, and connected to a corresponding intermediate node (k1) between two phase windings of a ring structure.