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What types of servo motors are there?

They are primarily classified into two major categories: DC servo motors and AC servo motors. AC servo motors are further categorized into asynchronous AC servo motors and synchronous AC servo motors. Asynchronous AC servo motors typically consist of three-phase induction motors with squirrel-cage rotors. Based on rotor structure, synchronous AC servo motors are classified into two main types: electromagnetic and non-electromagnetic. Non-electromagnetic types are further subdivided into hysteresis, permanent magnet, and reluctance types. Currently, permanent magnet motors are predominantly used in CNC equipment and are referred to as Permanent Magnet Synchronous AC Servo Motors.
What types of encoders are compatible with servo motors?

Based on their working principles, encoders are classified into incremental, absolute, and sine-cosine types, with incremental and absolute encoders being the most common. Incremental encoders convert displacement into periodic electrical signals, which are then transformed into counting pulses; the magnitude of displacement is indicated by the number of pulses. For absolute encoders, each position corresponds to a specific digital code; consequently, the indicated value depends solely on the starting and ending positions of the measurement, independent of the intermediate process. Servo motors fitted with incremental encoders are the most widely applied, whereas servo motors with absolute encoders are typically used in scenarios where the exact position must be known immediately after power-on, such as in industrial robots.
What functions are available in a servo motor system?What application scenarios are suitable for each function?

Servo motor systems feature three primary functions: position control, speed control, and torque control. Position control is the most widely applied function, suitable for applications requiring high positional accuracy. Speed control is commonly found in applications where only precise rotational speed is required, with little to no requirement for positioning. Torque control is typically used in scenarios requiring real-time adjustment of the motor's output torque; in torque control mode, the rotational speed and maximum torque of the servo motor can be limited.
What is the positioning accuracy of the servo motor? Is the accuracy cumulative?

The positioning accuracy of a servo motor depends on the resolution of the encoder. Taking a 2500-line incremental encoder as an example, if the driver performs 4x frequency multiplication on the motor encoder signal input, the positioning accuracy of the controlled servo motor is ±1/(2500*4). Calculated in degrees, this is ±360/(2500*4)= ±0.036 degrees, and there is no cumulative error.
Why must servo motors be paired with drivers of the same brand and model?

When a servo drive precisely controls the speed or position of a servo motor, it must acquire feedback signals from the servo motor encoder. However, as the models and specifications of servo motor encoders vary across different brands, and motor characteristics differ, it is mandatory to use drives and motors from the same brand. Parameters such as phase current, phase resistance, and phase inductance differ significantly between models. Matching a motor with an incompatible servo drive model can result in abnormal motor operation or false drive alarms; therefore, matching the specific model is required.
What is the relationship between torque, power, and speed in servo motors?

The servo motor provides constant torque output within the rated speed range. Above the rated speed, it provides constant power output, with torque decreasing as speed increases.

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