DC Motor Fan Technology of Hayes™
A direct current (DC) motor is a fairly simple electric motor that uses electricity and a magnetic field to produce torque, which turns the motor. At its most simple, a DC motor requires two magnets of opposite polarity and an electric coil, which acts as an electromagnet. The repellent and attractive electromagnetic forces of the magnets provide the torque that causes the DC motor to turn.
A DC motor requires at least one electromagnet. This electromagnet switches the current flow as the motor turns, changing its polarity to keep the motor running. The other magnet or magnets can either be permanent magnets or other electromagnets. Often, the electromagnet is located in the center of the motor and turns within the permanent magnets, but this arrangement is not necessary.
Electrical current is supplied to the coils of wire on the wheel within the DC motor. This electrical current causes a magnetic force. To make the DC motor turn, the wheel must have be negatively charged on the side with the negative permanent magnet and positively charged on the side with the permanent positive magnet. Because like charges repel and opposite charges attract, the wheel will turn so that its negative side rolls around to the right, where the positive permanent magnet is, and the wheel’s positive side will roll to the left, where the negative permanent magnet is. The magnetic force causes the wheel to turn, and this motion can be used to do work.
DC motors are used for a variety of purposes, including electric razors, electric car windows, remote control cars, and now, used in propelling the blades of Ceiling Fans! The simple design and reliability of a DC motor makes it a good choice for many different uses, as well as a fascinating way to study the effects of magnetic fields.
Power Inverter Technology: Integrated in the DC motor for Ceiling Fans
A power inverter, or inverter, is an electrical device that changes direct current (DC) to alternating current (AC); the converted AC can be at any required voltage and frequency with the use of appropriate transformers, switching, and control circuits.
Solid-state inverters have no moving parts and are used in a wide range of applications, from small switching power supplies in computers, to large electric utility high-voltage direct current applications that transport bulk power. Inverters are commonly used to supply AC power from DC sources such as solar panels or batteries.
Revolutionary NEW Technology that makes Ceiling Fans over 70% more efficient!
Unlike AC motors that use electricity to create a magnetic field, DC motors have their own built-in permanent magentics, so they use 3 to 5 times less electricity. DC motors that are capable of running off standard household AC current have been around for quite some time, so you would think that ceiling fans manufacturers would have started using them a long time ago. However, there is a lot more to making a DC motor work with AC current than simply inserting it into a fan that normally uses an AC motor. There are sophisticated built-in electronics that are necessary in order to allow a brushless DC motor operate from typical household AC electricity. Until recently, these electronics were far too costly, so it did not make sense to use them in ceiling fans. But things have changed.
The answer is yes…in most cases. Because the DC motors are more technologically advanced and require more sophisticated onboard circuitry, you can expect to pay a bit more for a fan that has a DC motor in it.
The armature of a typical DC motor
The armature of a typical DC motorThe article How Electric Motors Work explains how brushed motors work. In a typical DC motor, there are permanent magnets on the outside and a spinning armature on the inside. The permanent magnets are stationary, so they are called the stator. The armature rotates, so it is called the rotor.
The armature contains an electromagnet. When you run electricity into this electromagnet, it creates a magnetic field in the armature that attracts and repels the magnets in the stator. So the armature spins through 180 degrees. To keep it spinning, you have to change the poles of the electromagnet. The brushes handle this change in polarity. They make contact with two spinning electrodes attached to the armature and flip the magnetic polarity of the electromagnet as it spins.
This setup works and is simple and cheap to manufacture, but it has a lot of problems:
- The brushes eventually wear out.
- Because the brushes are making/breaking connections, you get sparking and electrical noise. The brushes limit the maximum speed of the motor.
- Having the electromagnet in the center of the motor makes it harder to cool.
- The use of brushes puts a limit on how many poles the armature can have.
With the advent of cheap computers and power transistors, it became possible to “turn the motor inside out” and eliminate the brushes. In a brushless DC motor (BLDC), you put the permanent magnets on the rotor and you move the electromagnets to the stator. Then you use a computer (connected to high-power transistors) to charge up the electromagnets as the shaft turns. This system has all sorts of advantages:
The poles on the stator of a two-phase BLDC motor used to power a computer cooling fan. The rotor has been removed:
- Because a computer controls the motor instead of mechanical brushes, it’s more precise. The computer can also factor the speed of the motor into the equation. This makes brushless motors more efficient.
- There is no sparking and much less electrical noise.
- There are no brushes to wear out.
- With the electromagnets on the stator, they are very easy to cool.
- You can have a lot of electromagnets on the stator for more precise control.
- The only disadvantage of a brushless motor is its higher initial cost, but you can often recover that cost through the greater efficiency over the life of the motor.
Advantages of DC motors
Speed control over a wide range both above and below the rated speed: The attractive feature of the DC motor is that it offers the wide range of speed control both above and below the rated speeds.
High starting torque: DC series motors are termed as best suited drives for traction applications used for driving heavy loads in starting conditions. DC series motors will have a staring torque as high as 500% compared to normal operating torque.
Accurate steep less speed with constant torque: Constant torque drives is one such the drives will have motor shaft torque constant over a given speed range. In such drives shaft power varies with speed.
Quick starting, stopping, reversing and acceleration
Free from harmonics, reactive power consumption and many factors which makes DC motors more advantageous compared to AC induction motors.
Energy Saving Fan
Brushless DC Motor energy saving fan is more efficient at converting electricity into mechanical power than a brushed DC motor fan. This improvement is largely due to the absence of electrical and friction losses due to brushes. The enhanced efficiency is greatest in the no-load and low-load region of the motor’s performance curve. Brushless DC motor energy fans are micro processor-controlled to keep the stator current in phase with the permanent magnets of the rotor, requiring less current for the same effect and therefore resulting in greater efficiency and less power consumption.
Brushless DC motor energy saving fan offers several advantages over traditional brushed DC motor energy fans, including more torque per weight, more torque per watt (increased efficiency), increased reliability, reduced noise, longer lifetime (no brush and commutator erosion), elimination of ionizing sparks from the commutator and overall reduction of electromagnetic interference (EMI). With no windings on the rotor, our energy saving fans are not subjected to centrifugal forces, and because the windings are supported by the housing, they can be cooled by conduction, requiring no airflow inside the motor for cooling. This in turn means that the motor’s internals can be entirely enclosed and protected from dirt or other foreign matter.