Coil Winding Design

An electromagnetic coil is produced by winding an electrical conductor, such as wire, into the shape of a coil, spiral, or helix. The design of the coil is based on fulfilling specific purposes, taking into account parameters like inductance, resistance, and the desired strength of the magnetic field. These factors greatly influence the coil winding design.

Electromagnetic coils find application in devices where electric currents interact with magnetic fields, such as inductors, electromagnets, transformers, and sensor coils. Either an electric current is passed through the wire of the coil to generate a magnetic field, or an external time-varying magnetic field is passed through the coil to generate a current in the conductor.

Inside electromagnetic coils, there is a magnetic core made of a magnetic material, which is intended to increase the magnetic field. The core is not directly linked to the coil. As the current passes through the coil, it magnetizes the material, and the magnetized material’s field adds to the field produced by the wire.

Types of Winding. Brief Characteristic and Scope of Application

According to the design and technological features, the following types of winding can be distinguished: cylindrical, disk, continuous, twisted, and screw-type (helical) windings.

The choice of winding type depends on the number of turns, size, cross-sectional shape and number of parallel wires, as well as cooling method, transformer power and other factors. When choosing the type of winding, the requirements for it, as well as the technological feasibility of its implementation should be taken into consideration.

• Cylindrical winding. A single-layer, double-layer, or multi-layer winding produced of both round and rectangular wire. The winding layer is made up of coils laid closely in the axial direction. The turns consist of one or more parallel wires, usually located next to the axial direction of the winding. The connection between the layers is carried out by transition without soldering. Multiple advantages of this type of winding, such as simplicity of manufacturing, good cooling and low probability of short circuit between turns, as well as compactness and good insulation of layers, create wide possibilities of using it in powerful high-voltage supply transformers.
• Disk winding. Consists of a series of separately wound single or double (paired) coils, each of which has several turns, wound one on another helically in the radial direction. Depending on the voltage class, the coil windings can have additional (coil) insulation common to all turns. Disc windings differ from layered ones by greater mechanical strength in the axial direction.
• Continuous winding. Consists of a series of coils located in the axial direction and connected to each other in series without soldering. Turns are wound flat on top of each other in spiral order. The advantage of a continuous winding is its large end bearing surface and therefore greater stability with respect to axial forces during short circuits, as well as a large cooling surface. Thus, continuous winding is used in transformers in a wide range of capacities and voltages.
• Twisted winding. One of the best high-voltage windings widely used in modern transformers of 110–1200 kV voltage classes. When developing transformers with an operating voltage above 500 kV, the twisted winding is the best choice, capable of providing the required level of pulse insulation strength.
• Screw-type winding (sometimes called helical winding). Consists of a series of turns wound along a helical line, with oil channels between them. Each coil consists of several identical parallel rectangular wires laid flat in the radial direction. The helical winding is sometimes called multi-parallel winding, since the total number of parallel wires in the winding of a high-power transformer can reach many tens. The parallel wires of the screw-type winding are laid concentrically and at different distances from its axis.

To learn more about Benatav’s coil winding technology and its applications, read our White Paper.

Micro Coil Winding

Winding regular-sized coils can be done serially, but winding micro coils requires specialized equipment. Benatav has developed state-of-the-art methods and equipment that enable the winding of micro coils to a degree not previously achievable.

Manufacturing a micro coil with up to 2000 turns requires significantly reducing the wire’s thickness. Benatav is one of the few companies in the world working with extremely fine wires. Using custom micro-machining technologies, the company can manufacture coils with over 1000 windings that are smaller than the head of a pin.

Benatav’s core competency lies in engineering design according to customer requirements. With over 30 years of engineering experience, Benatav’s developers collaborate with the customer’s engineers from the early stages to ensure precise and professional design that meets all engineering requirements while adhering to the highest quality standards and ensuring maximum manufacturability. The design process involves an interactive customer-provider approach, including joint tests and experiments in the Benatav labs, until a prototype design is finalized.