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- Motors convert electrical energy into rotational movement.
Conventional Motors - Two Connections
Normal motors run at a speed determined by the power supply voltage and the load on the motor. This is fine for devices like cooling fans or motors used to drive vehicles.
- These spin in a fairly uncontrolled way.
- They are useful for propelling vehicles, powering fans or spinning the washing.
- It is possible to measure how fast the motor is spinning but the exact position of the motor is not generally known.
- These motors can be any size including huge motors for driving ships or trains.
- Difficult to control small movements
- Easy to make a big powerful motor
- Easy to make a motor that runs at high speeds
- To control speed, a closed loop control system is needed with negative feedback of the speed measurement.
- Simple switches or electronics used for power control
- Efficient - most of the electrical energy is converted into mechanical form
- QE2 Engine Room - Big Motors 9 metres across.
- MOSFET switches are commonly used.
- MOSFET source followers are used less often.
- H-Bridge controllers containing four MOSFET switches are good for reversible motors.
- Chips are available to control the motor power using pulse width modulation.
- H-Bridge chips are available too. These prevent accidental misconfiguration of the H-Bridge circuit.
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