Fans are used in several industries and applications to move air for heat transfer, (such as convection cooling and heating), air exchange (such as ventilation and exhaust) or filtration. They typically consist of a moving element, like blades or vanes, connected through a shaft to a motor that drives the fan. Fans are categorized according to the type of blade, the direction of air travel and the type of motor it uses. Different types of fan motors affect fan speed, power and efficiency, which is why choosing a fan with a motor best suited for a specific application is crucial.

Motors

The fundamental purpose of the fan motor is to convert electrical energy into mechanical energy that rotates the fan blades. Since the electrical energy can come in the form of either alternating current (AC) or direct current (DC), fan motors fall into either AC or DC motors.

AC fan motors

An AC motor – often called an “induction motor” – consists of an outer stationary stator ring ofFigure 1. Axial fan with AX induction motor. Source: Pelonis Technologies, Inc. electromagnet coils that surround a freely rotating rotor made of a conducting material (Figure 1). When current is applied to the coils, a magnetic field is created, which causes the rotor to rotate. Controlling the speed of AC fans requires the use of capacitive or phase frequency converters that can be expensive, inefficient and noisy, making AC motors about 30% less efficient than DC motors.

Brushed DC fan motors

Brushed DC motors have a stationary stator that consists of stationary permanent magnets or electromagnets around a freely rotating rotor that consists of electromagnetic coil. When power is supplied to the coils through a mechanical connection between the stationary brushes and a rotating commutator, the resulting electromagnetic fields cause the rotor to rotate. Since the stationary brushes are in constant contact with the rotating commutator, a common failure mode of brushed DC motors is excessive friction and wear of the brushes.

Electronically commutated fan motors

Electronically commutated (EC) or brushless DC (BLDC) fan motors contain a freely rotating permanent magnet rotor that is surrounded by stationary coils that are fixed in place on the stator. A switching electronic controller or microprocessor modulates the current through the stator coils, causing the rotator to rotate. Since the EC motor does not contain brushes and a commutator that form a mechanical connection, EC fan motors have a higher durability than brushed DC motors.

Pelonis Technologies has developed the flat motion series of external rotor BLDC motors with a unique design that allows for continuous operation at high speeds and enhanced passive heat dissipation and control (Figure 2). These motors have several advantages, including a small footprint, lighter weight, greater power and longer life.

Figure 2. External rotor flat BLDC motors. Source: Pelonis Technologies, Inc

Pelonis Technologies overview

Pelonis Technologies has the knowledge and skills to answer any questions customers may have and find the product that suits their exact needs. With over 25 years of product development and manufacturing experience, Pelonis Technologies' management team and engineers are committed to providing exceptional quality, product innovation and service at competitive pricing. More information about Pelonis and their fan motors can be found at the Pelonis Technologies website.