The performance difference between synchronous and asynchronous spindle servo drives in the core transmission system of industrial automation lies in the fundamental differences in their working principles. This difference not only determines the operating characteristics of the motor, but also directly affects the machining accuracy and energy efficiency of equipment such as CNC machine tools and automated production lines. Thoroughly analyzing the principle differences between the two is the key to precise selection and efficient application.

The difference between rotor structure and magnetic field source is the starting point for the differentiation of the principles of the two types of actuators. The permanent magnet synchronous motor mounted on the synchronous spindle servo drive has a rotor made of permanent magnet materials such as neodymium iron boron, which can generate a constant magnetic field without the need for an additional excitation source. When three-phase AC power is applied to the stator winding, a stable rotating magnetic field is generated, and the magnetic field of the rotor permanent magnet actively attracts the rotating magnetic field of the stator, driving the rotor to rotate under electromagnetic tension. This structure fundamentally avoids rotor excitation losses in synchronous drives, laying the foundation for efficient operation.

The core of asynchronous spindle servo drive is the induction motor, and the rotor is mostly a squirrel cage structure with no independent magnetic field. Its work relies on the principle of electromagnetic induction: the rotating magnetic field of the stator cuts the stationary rotor conductor, inducing electromotive force and current in the closed rotor circuit. The current carrying rotor conductor is driven to rotate by electromagnetic force in the stator magnetic field. This "induction generated" magnetic field mechanism inevitably leads to rotor resistance losses in asynchronous drives, resulting in relatively low energy utilization efficiency.

The essential difference in speed relationship is a significant feature of the two types of drives. The rotor speed of a synchronous drive during steady-state operation is strictly equal to the synchronous speed of the stator rotating magnetic field (calculated as Ns=120 * f/P, where f is the power frequency and P is the number of motor poles), and the two are "synchronized", transmitting torque only through a fixed power angle. This synchronous characteristic results in high speed accuracy and much smaller speed fluctuations compared to asynchronous drives, making it particularly suitable for precision machining scenarios.

Asynchronous drives have an unavoidable "slip rate" - the rotor speed is always lower than the stator synchronous speed, which is a necessary prerequisite for generating torque. If the rotor speed is equal to the synchronous speed and there is no relative cutting of the magnetic field, the induced current and torque will disappear. Taking a 4-pole asynchronous motor driven by a 50Hz power supply as an example, with a synchronous speed of 1500RPM, the actual operating speed is usually only around 1450RPM. This speed deviation makes it difficult to meet high-precision control requirements.

The difference in principle directly leads to performance differentiation: synchronous drivers have a power factor close to 1, an efficiency about 8% higher than asynchronous drivers, and maintain stable and efficient performance over a wide load range; Although asynchronous drives have a simple structure and strong overload capacity, they have low torque and severe heating at low speeds. In CNC machine tools, the high precision and fast response of synchronous drives ensure the quality of complex surface machining; In heavy-duty scenarios such as mining machinery, the high reliability of asynchronous drives is more advantageous.

In short, the principle difference between synchronous and asynchronous spindle servo drives lies in the core difference between "active magnetic field synchronization" and "induction magnetic field asynchronous". This difference determines the distinction between accuracy, efficiency, and applicable scenarios, and provides a clear basis for the precise selection of industrial equipment.