Brushed DC Motors: All You Need to Know
Your life basically gets controlled by technology and electric motors are more prevalent than you may think. Did you know there’s one helping to make your coffee in the morning?
Whether you’re curious about how these things work or if you’re looking for the ideal motor for one of your own projects, we can help you better understand them. Thanks to people’s innovative ideas there are quite a few types to consider, so pick wisely.
A Short History of the Electric Motor
Where it All Started
The idea for the first electric motor was sparked by something as simple as a magnet. Although there were a few individuals experimenting with similar inventions we really owe gratitude to Thomas Davenport for the brushless electric motor as we know it today.
Davenport—an ordinary blacksmith—saw Joseph Henry’s electromagnet in New York in the early 1830s. He was so sure it could do more than being a spectacle (as it was at that point) that he sold a horse to raise the capital and purchase his own.
By taking it apart and studying it he realised the possibilities. He used four magnets and discovered the value of a brush & commutator switching device. With this he made his device do a full rotation when switched on, thanks to the interaction between the magnets. And so the electric motor was born.
In 1837 his electrical motor was officially patented but it took years for industries to realise its potential.
How it Works
The brushed DC motor we know today has these components:
The unique positioning of magnets, wire coils and the rotor causes the flow of electricity. This in turn creates a magnetic field powerful enough to push the coils away from the magnets. Finally the rotor will then start turning.
Let’s Talk Efficiency
The benefit of a brush DC motor is that you can easily vary its speed-torque ratio. But how efficient is the motor you’re using really? This is measured in terms of the ratio between:
- Mechanical power output: This is the torque and speed required.
- Electrical power input: Determined by voltage and the current supplied.
Because you lose some power during the conversion, there are continual attempts to improve motors by minimising this loss.
So where can you use these dynamic motors?
What are Brushed DC Motors Used for?
As stated these motors are used all around us.
Brushed Motors in Your Home
In your kitchen you’ll find many appliances that require movement to help you cook or prepare food. To your benefit you’ll find a motor inside:
- A mixer or blender
- The microwave oven
- The refrigerator’s fan
- The electric can opener
These appliances move when you supply electrical current. They move and work so that you don’t have to apply effort yourself. That’s the beauty of an electric motor: It does all the hard work for you. This also enables your vacuum cleaner to work and the electric screwdriver to turn.
Electric motors make for luxury living with garage door openers, fans and the power windows in your car.
Brushed Motors Elsewhere
This same principle is helpful in many other industries:
- In banking you have the benefit of an ATM
- In the industrial sector motors are used for automation and operating heavy equipment
- Modern robots incorporate motors
- In the medical arena electrical motors help in diagnostic equipment
Of course there are many ways to drive appliances and machines. What will you find inside the ones not fitted with a brushed motor? Another popular option is a brushless motor.
Brushed Motors vs Brushless Motors—Is There a Better Option?
A brushless motor differs from a brushed motor in that it doesn’t contain any brushes. Instead of brushes helping to generate energy a brushless motor’s magnet turns thanks to hall-effect sensors and Fleming’s left hand rule.
A brushless motor has the advantage of fewer components that can wear down but a brushed motor is more budget friendly. If you need to pick between the two you must take all factors into consideration and you’ll learn more about it here.
But these aren’t the only motors you’ll find these days. Thanks to technological developments over the years many other devices have come onto the market. One is called a coreless motor.
What is a Coreless Motor and its Benefits?
This development in the electrical motor arena started in the 1930s. Once again it took a few decades until the 1960s before society started applying it excessively.
Coreless Motor Explained
In a traditional electrical DC motor you’ll find the coils wound around iron laminations. Not so in a coreless motor because the coil is actually a hollow cylinder and there is no iron core.
The Benefits of a Coreless Motor
This one seemingly small change makes a huge impact:
- With no iron core there’s no magnetic field that interacts with the laminations. This change improves efficiency—even up to 85%–and you’ll experience less cogging.
- These motors are often very small which makes more applications possible such as using them to make small dynamic pumps.
- The machines are lighter.
- The brush and commutator will last longer because there’s less inductance.
The development of the electrical DC motor has come a long way. What else will we see in future if someone as innovative as Davenport can develop this industry even further? For now we can all be thankful these motors make life so much easier.