Trapezoidal Coil

Introduction to Trapezoidal Coils

Trapezoidal coils are special coils formed by winding wires around a trapezoidal frame or core. Their core feature is that they present an overall "trapezoidal" geometric contour (i.e., the two pairs of opposite sides are parallel and of unequal lengths, and the two waist sides are inclined). They can adapt to the irregular Spaces in equipment and at the same time regulate the magnetic field distribution through the trapezoidal structure to meet the requirements of specific scenarios.

I. Basic Structure

Wire: Commonly used is enameled copper wire (silver wire can be selected for high-frequency scenarios), with an insulating coating (such as polyurethane) on the surface to prevent short circuits in adjacent wires and ensure the conductivity efficiency.

Trapezoidal frame: The core component that supports the wires and determines the size of the trapezoid (upper base, lower base, waist length). The materials are divided into two types: non-magnetic materials (such as plastic and ceramic) are suitable for scenarios where a uniform magnetic field is required. Magnetic conductive materials (such as ferrites) can enhance the local magnetic field and be used to improve the electromagnetic conversion efficiency.

Insulating encapsulation: The outer layer of the coil will be wrapped with insulating tape or epoxy resin to isolate electromagnetic interference, protect the wire from environmental corrosion, and at the same time fix the position of the wire (prevent the wire on the trapezoidal inclined edge from sliding).

Ii. Core Features

Strong spatial adaptability: The trapezoidal "unequal edge" structure can fit the irregular gaps in the equipment (such as the stator slots of motors and the corner areas of electronic devices). Compared with circular and square coils, it can make more full use of space and reduce installation waste.

The magnetic field can be direction-regulated: The inclined waist of the trapezoid can guide the magnetic field to converge towards the "long side" or the "short side" - for instance, when the short side is the small end and the long side is the large end, the magnetic field will diffuse towards the large end, expanding the coverage area of the magnetic field. Conversely, focus towards the small end to enhance the local magnetic field intensity.

Processing requires customization: The trapezoidal frame has no standardized specifications and needs to be customized according to the equipment space. When winding, the arrangement of the wires on the inclined waist needs to be precisely controlled to avoid local accumulation.

Iii. Main Uses

In the field of motors: Trapezoidal stator slots are suitable for some motors. After the coils are wound, they can fill the slot space, increasing the "slot filling rate" (the proportion of wire filling), thereby enhancing the motor's torque and efficiency. This is commonly seen in special motors and micro stepper motors.

Irregular parts of electronic devices: It is used in the corner areas of small devices such as mobile phones and sensors, for example, the trapezoidal gaps formed by the layout of components inside the device. Trapezoidal coils can be installed closely to avoid occupying core space.

Directional magnetic field scenarios: such as local magnetic therapy devices (focusing the magnetic field on a specific area) and small metal detectors (diffusing the magnetic field towards the long side to expand the detection range), achieving directional distribution of the magnetic field through a trapezoidal structure.

Iv. Simple Differences from Conventional Coils

Space utilization: Trapezoidal coils can adapt to irregular gaps and have a high utilization rate. Circular and square coils are only suitable for regular Spaces and tend to waste space in irregular areas.

Magnetic field regulation: Trapezoidal can directionally guide the magnetic field (focusing/diffusing); The magnetic fields of conventional coils are mostly "strong at the center and weak at the edges", and cannot be adjusted specifically.

Processing cost: Trapezoidal requires custom frame and winding parameters, which is slightly more expensive. The conventional coil frame is standardized, with simple processing and low cost.