I understand that a brush-less DC motor must have a controller which generates AC current to drive the unit. My question is; if i bypass the controller and connect the motor directly to a bridge rectifier, will I generate power at a reasonable efficiency.If I used a 24v brush-less DC motor, would I approximately produce power of 24v?Thanks for technical expertise!
There are 2 types of brushless motors. 1 is actually an AC motor, 3- phase,that is driven from an inverter from DC to AC. It is common in such as electric powered models, and varying the AC frequency is used to control speed. Such a motor might be used as an alternator to produce AC electricity. Then there is the brushless DC electronically commutated type motor, common in such as computer cooling fans. They cannot be used as a generator.
Rick and Brian T have given first class answers so I will limit my answer to describing a case where motors are used as generators. Many turbine driven aircraft use the same rotating DC machine as the starter motor and the generator, or at least one of the generators. This is a fairly commonly asked question and as usual, someone has shown that they do not understand the self-excited DC generator. These machines do not need a separate excitation supply because they generate their own from the residual magnetism in the stator laminations. An old style DC car generator is a classic example of this.
