How can convert a electrical motor in a generator?
A permanent magnet DC motor with a commutator can be used as a DC generator simply by connecting an electrical load to the terminals and turning the shaft. Very small motors of that type are sold as toy and hobby items. Somewhat larger motors of that type are used for such things as electric windows in cars. Motors that are called brushless DC motors are similar to permanent magnet synchronous motors. They can be used as AC generators simply by connecting a load and turning the shaft. However, some such motors have an electronic commutator inside that will probably prevent using the motor as a generator. Other types of motors can be used as generators, but each type of motor has its own specific requirements. There is a wide range of difficulty and complexity involved. Many DC motors that have a field winding can be operated as generators, but the field winding connection may need to be changed and/or a separate field excitation circuit may need to be added. Three phase synchronous AC
