Traction Motor: Explanation, Types, and Applications

Posted by Mitsubishi Electric on May 20th, 2021

A traction motor is a type of electric motor that’s used for the propulsion of a vehicle. Being an electric motor, it takes electrical energy as a source and converts it into mechanical energy which helps push a locomotive forward. These are primarily used in electric rails, elevators, roller coasters, conveyors, and trolleybuses. There are divided into two categories.

Types of a Traction Motor

1. DC Traction Motors

DC motors have always been a highlight of traction motors around the world. A DC motor can function solely on electricity or an electricity-diesel hybrid. It primarily consists of two parts: a fixed field and a rotating armature. The fixed field has tightly wound coils of a wire that are fitted inside the motor case. The armature is a different set of coils wound around a central shaft. Both of these are connected through spring-loaded contacts called “brushes” or a commutator. The function of a commutator is to collect the terminations from armature coils and create a sequence of current flow by distributing the energy in a circular pattern.

In other words, a DC motor works by creating a connection between the armature and field. When a current is passed through its circuit, the reaction between the armature and field causes the armature to turn, which creates mechanical energy. The key reason DC motors have stayed as a highlight of traction motors is that they have low resistance and can endure high current. When voltage is applied to the circuit, a high current is created, which produces strong torque power.

2. AC Traction Motors

The structure of AC motors and DC motors is the same. DC motors were popular when traction motors were introduced because DC motors provided the right torque characteristic needed for heavy vehicles. However, most electric vehicles now use AC motors because they have been able to match the power produced by DC motors.

Additionally, AC motors are easier to construct since they require no mechanical contact (commutator) to work, and they are lighter than DC motors. Many modern electronics use AC motors because they improve traction and adhesion. AC motors are also more robust and easier to maintain. But one of the main reasons why AC traction motors dominate the DC traction motors in the 21st century because these motors can be controlled to a fine degree using a microprocessor. Where the DC regeneration fades quickly at low speeds, an AC motor can regenerate a current when it’s down to almost a stop.

Applications of a Traction Motor

Railways

Railways have been one of the most-used applications of traction motors. Trains around the world are slowly opting for electric options. Traction motors have served as a great alternative ever since they came into existence. Even the Delhi Metro uses traction motors. Because of the usage in Delhi Metro, reputed traction motor manufacturers in India have ramped up their production. Most railway systems, including Delhi Metro, use AC traction motors.

Road Vehicles

As the world is slowly moving towards sustainable fuel options, vehicles need motors that can run on a different energy. Every electric vehicle is powered by a traction or induction motor now. This has come up as a great alternative and many automobile manufacturers are opting for it.