There may be usually confusion concerning the usage of external diodes when power provides are used to power DC motors. Most individuals know diode needs to be used, however are not sure the place to put them or what their objective is.
From a power provide concern there are two sorts of DC motors; a brushed DC motor and a brushless DC motor.
Brushed DC motors
With this sort of motor, the magnets are stationary and the coil spins. Electrical energy is transferred to the spinning coil by way of “brushes”.
Some great benefits of this sort of motor are low preliminary value and simple pace management.
When the power is interrupted, the motor coil will act like an inductor and will attempt to proceed to provide present, successfully turning into an inverted voltage source. It will apply a reverse polarity to the power provide and may cause injury. (Again EMF – Electro-Magnetic Flux)
Through the use of a diode, as proven under, the diode supplies a present path for the reverse motor present and will clamp the reverse voltage to a stage no better than the ahead voltage drop of the diode. This protects the power provide’s output capacitors and different elements from being confused by the reverse voltage.
Brushless DC motors
Brushless DC motors, sometimes called BDCMs or BLDC motors, have everlasting magnets that rotate and the armature is mounted.
Though dearer, they're extra dependable in the long run as there is no such thing as a brush or commutator put on and place management is extra correct.
When the motor is turned off or reversed, it'll act as a generator and produce a high voltage spike. This spike may cause the power provide’s overvoltage protection to journey, shutting down the unit.
Through the use of a diode in collection with the output, as proven under, the spike might be blocked from interfering with the power provide.
In each circumstances a basic objective diode can be utilized, offering that the voltage and present scores for the diode are accurately calculated.