Should electromagnet or permanent magnet be used in generator?

For the generator industry, customers often have such concerns when purchasing magnets. Is it better to install permanent magnet or electromagnet?

Permanent magnet: also known as permanent magnet, with high coercivity, high remanence, once magnetized, it can maintain uniform movement with magnetic raw materials. In the process of operation, the permanent magnet works in the second quadrant demagnetization part of deep magnetic saturation and magnetization.

Electromagnet: a device that generates electromagnetism when electrified. The outer side of the iron core is wound with a conductive winding matching its power. The current carrying coil is magnetic like a magnet. People usually make it into strip or horseshoe shape, so that the iron core is easier to magnetize. In addition, in order to demagnetize the electromagnet immediately when the power is off, people often use soft iron or silicon steel materials with faster demagnetization.
The above is a brief introduction of the two kinds of magnets. These two kinds of magnets are useful in generators. Small generators basically use permanent magnets, while large synchronous generators use electromagnets. The exciting current is added to the stator coil to form a strong magnetic field. It depends on the specific situation. For example, the generator on the car is an electromagnet. Previously, the one used by customers on the hand generator is a bonded NdFeB permanent magnet.