Resolvers

Principle of resolver operation

The operation is based on two perpendicular excitation and reception coils and a rotating rotor. When power voltage is applied to the excitation winding, the system generates a pair of sine/cosine signals whose amplitudes reflect the angular positions. Such an analog reading is highly resistant to interference, and the simple design without optical elements means the resolver performs well in harsh conditions. Although many applications today are handled by encoders and measuring systems in terms of accuracy, in numerous industrial environments, resolvers prove to be more durable and predictable over a long lifecycle.

Resolver applications

You will find resolvers in servo drives, robot arms, CNC axes, extruders, and overhead cranes – wherever long-term operation and resistance are a priority. Popular manufacturers like Siemens widely use resolvers in solutions that must operate for years without downtime. Thanks to stable sin/cos signals, integration with measuring systems and controllers is predictable, and maintenance is simpler. In many automation systems, the resolver remains the first choice, especially for field applications or plants with a heightened risk of contamination.

Device selection

When choosing a resolver, consider the operating environment (temperature, vibration, dust), requirements for the sin/cos signal bandwidth, and mounting mechanics. The shaft diameter, mounting method, and compatibility with servo drive parameters will be important. If the project involves a small electric motor, a compact format with an appropriate protection class and durable bearings will ensure a long lifespan. In larger drives, mechanical durability and characteristic stability over time are crucial so that the drive and controller maintain consistent regulation regardless of changing conditions.

Integration and compatibility in industrial automation

Sin/cos signals from resolvers usually go to dedicated converters (R/D) which transform the analog waveform into a digital format for the servo amplifier or controller. This path allows for seamless replacement of encoders where durability and stability are priorities. In many designs, it is possible to change the position sensor without mechanical alterations - simply check electrical compatibility and dynamic parameters to safely connect the resolver into the existing system.

Benefits of using a resolver

In production realities, not only accuracy but also predictable maintenance costs are important. A resolver reduces susceptibility to dirt, vibrations, and temperature fluctuations, which directly translates into a lower risk of downtime and service costs. When a process needs to operate "always" and the environment is far from laboratory conditions – the analog approach is simply often more sensible.

When to use a resolver, and when an encoder?

If the goal is maximum resistance and durability in harsh conditions, a resolver will be the right choice. When the highest resolution and rich digital interfaces are crucial – an encoder will be more suitable. Thanks to their simplicity and resistance, resolvers still effectively secure critical axes and positions in devices where a long, stable operating cycle is a priority.

Resolvers, encoders, and measurement systems for your line at PLE Service

In our offer, you will find resolvers compatible with popular servo drives and accompanying elements for efficient integration. We advise on selection based on environment, mechanics, and sin/cos parameters, to ensure consistency with the rest of the system. We also offer diagnostics and service – from signal verification to sensor replacement in the machine – to keep your machinery running smoothly.