HOW DO ELECTRIC MOTORS WORK?

From basic principles to PMSMs, discover how the motors featured in T&D’s powertrains function.

Electric motors have a variety of different applications, from small electric toys to electric motorbikes and more, but have you ever wondered how they work? Join us as we delve into the basic principles, different types of electric motors, and why Permanent Magnet Synchronous Motors (PMSMs) are the ultimate choice for electric motorcycle powertrains.
 

The Fundamentals

There are several different types of motors that have slightly different functioning; however, they all work on the same principles, utilizing magnets and electromagnetic fields to generate mechanical force. 

To start, let’s go over the basics. Magnetic forces are attracted to their opposite poles (positive to negative) and repelled by likes (negative and negative or positive and positive). An electromagnetic field is formed by winding wire around a metal pole connected to an electric current source (i.e. a battery). This creates polarity within the pole, with one side positively charged, and the other negatively charged. The pole is then suspended in the middle through an axle so that it can turn; this what we call a rotor. 

The rotor is then suspended and surrounded by a horse-shoe shaped magnet. The attraction and repulsion of the different poles of the magnet (i.e. positives being attracted to negative poles and repelled by the positive poles) generates movement as they seek equilibrium, therefore generating mechanical force. 

The issue then lies with how to keep this rotor moving; to do this the poles of the rotors electromagnetic field need to alternate. This occurs when electrons flow in the opposite direction. There are a couple of ways that we can do this; one way to achieve this is switching the battery connection, allowing the rotor to complete a half turn with each flip. Properly timing this flip allows for smooth rotation of the rotor and the generation of force. In practice, an alternator is a part of the electric circuit to alternate the electric current.

This example illustrates an Alternating Current (AC) motor. Different types of motors, such as Direct Current (DC) motors, Induction Motors, and Permanent Magnet Synchronous Motors (PMSMs) operate on similar principles. Now we’ve covered the basics, lets delve deeper. 

Direct Current (DC) Motor

DC motors operate similarly to AC motors, however, a commutator is used to keep the polarity alternating and the rotor turning. The alternating polarity creates the torque required to produce mechanical power. DC Motors are utilised in a variety of electric devices, from small toys to vehicles. 

Induction motors

Induction motors are a type of AC motor, however what differentiates it from the basic AC motor is that the electromagnetic field is arranged on the outside, making up what is called the stator, and is linked to the power supply; meanwhile, the rotor is comprised of conductive bars instead of magnets. This allows the stator to produce a rotating electromagnetic field, turning the rotor and generating mechanical force.
 

Permanent Magnet Synchronous Motors (PMSMs)

At T&D all our powertrain motors are PMSMs, which are considered a hybrid between an induction motor and a DC motor. As the name suggests, there are permanent magnets; these are located in the rotor, and can be situated either internally or externally. The rotating magnetic field is generated by the stator, causing the rotor to move, converting electrical energy to mechanical energy. At synchronous speed, the rotor field magnetically locks with the stator poles, propelling rotation, and producing torque.

What are the advantages of PMSM?

There are several advantages for PMSMs over other motors. These motors are significantly more efficient, offer dynamic performance with ability to operate in a wide speed range, and are best suited for functions that require high performance and energy efficiency. Additionally, they are generally simple in structure and compact compared to other motors. These qualities make them a popular choice for electric vehicles. For electric motorcycles in particular, their compactness and low weight, paired with high potential power and torque output, make them the ideal choice.   

At T&D we work with electric motorcycle manufacturing brands to create their ideal components for a variety of motorcycle categories, fine-tuning each part of the powertrain – including the motor – to ensure harmonious, optimized operation. Working collaboratively with partner motorcycle brands allows us to adjust components for diverse requests and iterations of end products. 

The latest example from the T&D range of drive systems to go through a design upgrade is the LI02 system, a simple yet robust design that’s engineered specifically for city commuter motorcycles. The smallest of details are assessed and refined in conjunction with feedback from partner brands, with the aim of achieving reliable, optimized performance for a daily-use vehicle. 
 

There is remarkable versatility in electric motors and how they function, among those PMSMs stand out for their blend of efficiency, dynamic performance, and compact design, making them ideal for powering electric motorbikes. T&D only utilises these motors in our powertrain systems, offering riders superior performance and responsiveness. 

Electric motorcycle product designers who are seeking the ideal motors for their project can use our innovative powertrain configurator tool to determine the optimum set of components to make up the complete drive system.