MEMS Switch On-Load Tap Changer for Transformer Voltage Regulation
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Solution Overview
Problem
Conventional on-load tap changers for high voltage transformers face issues such as mechanical switch contact failure, parasitic energy losses, and high maintenance costs due to their mechanical and semiconductor-based switching mechanisms, which are also large, slow, and noisy.
Innovation Solution
The implementation of micro-electromechanical system (MEMS) switch modules coupled with a controller to manage the switching operations in high power transformers, allowing for rapid and arcless switching with reduced failure modes and energy losses, by directly controlling MEMS switch transitions to achieve desired turns ratios and prevent circulating currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If mechanical switching assembly is used for on-load tap changer, then switching capability is achieved, but switch contact failure occurs frequently and maintenance costs are high
Solution Approach 1:
The patent replaces the conventional mechanical switching assembly with a magnetic field-based switching mechanism. The magnetic field is generated by a coil that actuates a movable arm to make or break electrical contacts, eliminating the need for complex mechanical interlocks, motors, and spring mechanisms. This substitution of mechanical systems with electromagnetic actuation reduces the number of mechanical moving parts and improves switching reliability.
2Speed
If semiconductor switching devices are used, then switching speed is improved, but parasitic energy losses and off-state leaks increase
Solution Approach 1:
The patent changes the switching mechanism from solid-state semiconductor devices to an electromagnetic actuation system. By adjusting parameters such as coil current, magnetic field strength, and arm movement velocity, the system achieves fast switching speeds comparable to semiconductors while avoiding their parasitic losses and off-state leakage problems. The magnetic field can be rapidly established and collapsed, enabling quick contact make/break without the continuous power consumption inherent in semiconductor switches.
3Ease of operation
If mechanical OLTC mechanisms are used, then switching function is achieved, but the mechanisms are large, slow and noisy
Solution Approach 1:
The patent replaces slow mechanical interlocks and motor-driven mechanisms with an electromagnetic actuation system. The coil-generated magnetic field rapidly moves the switching arm, achieving much faster switching speeds. The electromagnetic system also operates silently compared to mechanical components, and the overall device size is reduced by eliminating bulky mechanical assemblies.
4Object-affected harmful factors
If conventional OLTC switch assembly is immersed in insulating media, then arcing is reduced, but maintenance becomes costly and time consuming
Solution Approach 1:
The patent extracts the switching mechanism from the insulating oil or SF6 gas environment by using a magnetic field-based actuation system that can operate in air or vacuum. The electromagnetic coil and movable arm are designed to minimize arcing through controlled magnetic field collapse, eliminating the need for immersion in insulating media. This extraction simplifies maintenance by allowing easy access to components without handling hazardous insulating fluids.
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
MEMS switch technology enables cost-effective, high-speed switching with reduced failure modes and parasitic energy losses, eliminating the need for insulating media and simplifying maintenance, while providing a compact and efficient solution for transformer voltage regulation.
Implementation Method 1
The switches in the switching assembly are mechanically actuated on and off in a sequence coordinated by mechanical interlocks
Implementation Method 2
The magnetic field is generated by a coil that actuates a movable arm to make or break electrical contacts
Data Source
AI summary
An on-load tap changer (OLTC) for a transformer winding is disclosed. The OLTC includes a first MEMS switch coupled in series with a first tap on the transformer winding and a neutral terminal. The OLTC also includes a second MEMS switch coupled in series with a second tap on the transformer winding and the neutral terminal. The OLTC further includes a controller coupled to the first MEMS switch and the second MEMS switch, the controller configured to coordinate the switching operations of the first MEMS switch module and the second MEMS switch module to obtain a first predetermined turns ratio or a second predetermined turns ratio for the transformer winding.