The Impracticality of Converting a Generator to a Permanent Magnet Alternator

Convert a generator to a permanent magnet alternator? It's not as simple as it sounds, and here’s why.

Understanding the Fundamental Differences

The process of converting a traditional generator to a permanent magnet alternator involves numerous technical challenges. At its core, a generator is designed to produce a stable output voltage and current, often using a field winding that is regulated by a voltage regulator. In contrast, a permanent magnet alternator (PMA) relies on the consistent magnetic field of permanent magnets. This shift from an active to passive magnetic field generation system can significantly affect the overall performance and output.

Why It's Difficult to Convert:

Incompatible with Voltage Regulators: Generators depend on a voltage regulator to maintain a stable output voltage, but permanent magnet systems operate without such a regulator, leading to inconsistent voltage. Design Differences: Generators typically use a commutator and brushes to produce DC, whereas alternators generate AC. This requires a different coil configuration and different stator windings. Slip Rings vs. Commutators: Alternators require slip rings instead of commutators to handle three-phase AC power without sparking, which is a significant difference from generators. Complexity of Installation: Retrofitting a generator can essentially require a complete overhaul, including the removal of existing components and installation of new ones.

Key Differences in Design and Functionality

Generators and permanent magnet alternators serve fundamentally different purposes, due to their distinct designs and functionalities. Here’s a more detailed look:

Generators:

About 90% of the time, generators are used to produce both AC and DC electricity, and they typically consist of a set of coils inside a magnetic field. They rely on a commutator and brushes to convert the alternating current (AC) generated by the coils into direct current (DC). In a DC generator, the magnetic field is created by a field winding that is controlled by a voltage regulator to ensure a stable output voltage.

Permanent Magnet Alternators:

Alternators do not have a field winding, as they use permanent magnets to generate the magnetic field. They produce AC power and use slip rings to handle the three-phase output. Alternators often have a controllable field coil that allows for the adjustment of the output voltage and current.

Conclusion: Why It’s Better to Buy a New Alternator

Given the significant differences and the complexity involved in retrofitting a generator to function as a permanent magnet alternator, it is often more practical and cost-effective to purchase and install a new alternator. This approach ensures better performance, reliability, and efficiency, while also complying with modern engineering standards.

Remember, an alternator is designed to directly produce AC power, eliminating the need for a commutator and brushes, and offering a range of advantages in terms of efficiency and longevity.