Gradient Taper Coil

Top inner diameter 6, bottom inner diameter 8)) 0.5*2.2

Introduction to Polygonal Coils

Polygonal coils are made by winding wires around a polygonal skeleton or core (such as regular shapes like equilateral triangles, regular quadrilaterals, and regular hexagons, or custom shapes like trapezoids and irregular pentagons). The core lies in using the geometric characteristics of polygons to meet the requirements of different scenarios.

I. Basic Structure

Wire: Mostly enameled copper wire (silver wire is used in high-frequency scenarios), with an insulating coating to prevent short circuits and ensure conductivity efficiency.

Polygonal skeleton: Supports the wires and determines the shape of the coil. Non-magnetic materials (plastics, ceramics) are suitable for scenarios where a uniform magnetic field is required. Magnetic conductive materials (ferrites) can enhance magnetic fields and are used in motors, inductors, etc.

Insulating encapsulation: The outer layer is wrapped with epoxy resin or insulating tape to isolate interference, protect the wires, and enhance structural stability.

Ii. Common Types and Characteristics

Regular polygonal coils: such as equilateral triangles (small space occupation, suitable for narrow areas, with concentrated magnetic fields), regular quadrilaterals (simple processing, high space utilization, commonly used in wireless charging and motors), and regular hexagons (magnetic field distribution close to a circle, suitable for planar equipment, such as flat transformers).

Irregular polygonal coil: Customized according to the irregular space of the equipment (such as the corner positions of automotive sensors and special motors), it has high flexibility and can make full use of the space.

Polygonal Helmholtz coil: Composed of two parallel identical polygonal coils, it can generate a uniform magnetic field and is suitable for test samples of square, hexagonal and other shapes (such as Hall probe calibration, biomagnetical research).

Iii. Key Performance

Inductance value: It is related to the number of sides, the number of turns, and the material of the magnetic skeleton. The more sides, the more turns, and the higher the magnetic permeability of the magnetic skeleton, the greater the inductance value, which affects the energy storage capacity.

Magnetic field uniformity: The more edges there are, the closer it is to the uniformity of a circular coil. Combining with reasonable spacing (such as Helmholtz coils) can further enhance uniformity.

Resistance and heat dissipation: The longer and thinner the wire, the greater the resistance and the more heat it generates. Coils with more sides have a larger surface area and relatively better heat dissipation efficiency.

Iv. Main Uses

Wireless charging: The regular quadrilateral coil is compatible with rectangular devices such as mobile phones and has a high tolerance for horizontal misalignment. Regular hexagonal coils are used for charging flat plates and cars, providing more uniform magnetic field coverage.

Motor and sensor: Irregular polygonal coils are adapted to the special-shaped slots of the motor to enhance torque. Equilateral triangular coils are used in micro-sensors and stepper motors to reduce volume.

Magnetic field generation: The polygonal Helmholtz coil provides a uniform magnetic field for polygonal samples (such as square sensors), which is used for calibration and biomagnetic research. Regular hexagonal coils can also be used for high-frequency induction heating to avoid heating dead corners.

V. Differences from Circular Coils

Spatial adaptation: Polygons can fit the interiors of rectangular and irregular-shaped devices, with high utilization rates. Circular coils are only suitable for regular circular Spaces and are prone to waste of corners.

Magnetic field and processing: The magnetic field of a polygon with a large number of sides is close to a circle, but the processing requires a custom skeleton. Circular coils are easy to wind, have low costs and strong versatility.