Small Hydro Turbine Low Water Head Permanent Magnet Alternator Manufacturer

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What is the permanent magnet generator?

Permanent magnet generators are synchronous machines with rotor windings replaced by permanent magnets. They need no separate excitation so rotor excitation losses – about 30% of total conventional generator losses – are eliminated. This results in high power density and small size with the highest efficiency at all speeds, offering the maximum annual production of energy with the lowest lifetime cost.

The structure

The permanent magnet generator is mainly composed of a rotor, end cover, and stator. The structure of the stator is very similar to that of an ordinary alternator. The biggest difference between the structure of the rotor and the alternator is that there are high-quality According to the position of the permanent magnet on the rotor, the permanent magnet generator is usually divided into a surface rotor structure and a built-in rotor structure.

Working Principle

The permanent magnet generator uses the principle of electromagnetic induction in that the wire cuts the magnetic field line to induce an electric potential and converts the mechanical energy of the prime mover into electrical energy output. It consists of two parts, the stator, and the rotor. The stator is the armature that generates the electricity and the rotor is the magnetic pole. The stator is composed of an armature iron core, uniformly discharged three-phase winding, machine base, and end cover.

The rotor is usually a hidden pole type, which is composed of excitation winding, iron core and shaft, guard ring, center ring, and so on.

The excitation winding of the rotor is fed with DC current to generate a magnetic field close to the sinusoidal distribution (called the rotor magnetic field), and its effective excitation flux intersects with the stationary armature winding. When the rotor rotates, the rotor's magnetic field rotates together with it. Every time a revolution is made, the magnetic lines of force cut each phase winding of the stator in sequence, and a three-phase AC potential is induced in the three-phase stator winding.

When the pm generator is running with a symmetrical load, the three-phase armature current synthesizes to generate a rotating magnetic field with synchronous speed. The stator and rotor fields interact to generate braking torque. The mechanical torque input from the turbine overcomes the braking torque and works.

Benefits

• Premium efficiency at all turbine speeds
• Proven reliability with maximized energy yield
• Low cost of ownership in all aspects from purchase to downtime and maintenance
• Short circuit withstand without demagnetization
• Rotor with high overspeed endurance
• Bearing design avoiding circulating currents
• Compact size