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Brushed and brushless motors
Brushed Motors
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Brushed motors are the easiest type of motor to control and setup. As they work using a split ring commutator, the current is automatically changing direction on the coils as the motor spins around.
These motors only require two wires (+) and (-) and are much simpler to control the speed of. The basic function of an electronic speed control is to switch the supply voltage ON and OFF at different rates, if the motor only needs to turn slowly the ON signal will be given for a shorter amount of time than the OFF signal. This output signal is one of the reasons why you can hear a buzz on low throttle before the motor starts turning.
Brushed motors have the coil as part of the rotating armature so the commutators can change the direction of current as it spins around. These commutators generate an efficiency loss and are one of the reasons why brushless motors are starting to increase in popularity.
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Advantages
- Easy to setup and run.
- Fairly cheap to buy.
- They don't need any special speed controllers.
Disadvantages
- Get very hot if run at high speed for any length of time.
- Consume more current than brushless motors.
- Fairly slow compared to brushless systems.
Brushless Motors
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Brushless motors work very differently and need a special speed controller to make them work. They are very good for high speed applications and are a lot more efficient than their brushed equivalents.
The coil is often on the outer casing which means the motor also runs cooler since the coil can dissipate it's heat around the casing.
These motors work by activating different coils around the outside of the magnet. The speed controller then energises two coils at a time in a six sequence loop, this can be seen in the animation above.
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Advantages
- The motors run quiter due to their being less friction.
- They are much cooler, this is because of the coils being mounted on the outside of the case to allow the heat to dissipate quicker.
- They run at high speeds and use less current than the standard DC Brushed motors. This is because the coils are connected straight to the power instead of going through split rings and commutators.
Disadvantages
- They need special speed controllers to run them.
- Possibility of them getting damaged if spun without load.
Controllers!
Brushed Motor Controllers
When it comes to brushed motors, there are many controllers you can buy that do forward and reverse for model boats.
These controllers work using a pulsed voltage signal to the motor. The longer the 'on' pulse the faster the motor spins and vice versa, the shorter the 'on' signal the slower the motor spins. The best way to think of this is by switching a light bulb on and off rapidly, by doing this the light appears dimmer because it's not been given enough time to reach the 'on' of the 'off' state.
Brushless Motor Controllers
For a brushless motor it is
necessary to control it using a brushless controller. Brushless motors have three wires, they operate by switching on one coil at a time which changes the magnetic field within the motor to the next coil along, this means that magnets keep pulling towards the energised coil which makes them spin.
This is effectively what a brushed motor does, but the different coils are energised by means of the commutators rather than a separate controller.
I have tried both types of motors in the past and know a fair amount about them so if you need anymore information feel free to get in touch
here.
