In the field of industrial automation, the coordination between servo motors and drivers is like that of “muscles and the brain”. The choice of driver directly affects the precision, response speed and stability of the equipment. Whether it is machine tool processing, robot arms or intelligent logistics equipment, a suitable driver can enable the servo motor to perform at its best. This article starts from practical application scenarios and analyzes the core logic of driver selection to help you avoid common pitfalls such as “power mismatch” and “incorrect control mode”.
Clarify the Three Core Demands: Power, Precision and Control Mode
The selection of a servo driver should first match the motor characteristics and working conditions. The core indicators include:
Power matching: Reject “big horse pulling a small cart” or “small horse pulling a big cart”
The rated power of the driver should be consistent with the nominal power of the servo motor (within ±10%), too small will lead to overload alarm, and too large will waste costs and may cause interference.
Calculation formula: Driver power (kW) = Motor rated torque (N·m) × Rated speed (rpm) ÷ 9550, and a 20%-30% overload capacity should be reserved.
Precision and response speed: Select the control mode as needed
Position control: Suitable for machine tool positioning, indexing tables, etc., controlling the motor angle by receiving pulse signals, with an accuracy of ±1 pulse.
Speed control: Used for conveyor belt speed adjustment, fan constant speed control, and the speed fluctuation index should be paid attention to.
Torque control: Applicable to tension control, the driver should support torque mode and have high-precision current regulation capability.
Environmental adaptability: Temperature, protection level and installation space
For high-temperature environments, choose a driver with a temperature range of -10℃ to 60℃. In humid scenarios, select a protection level of IP54 or above to prevent dust and liquid intrusion.
Compact equipment should prefer ultra-thin drivers (thickness < 50mm), supporting DIN rail installation or integration at the motor end.
Core Parameter Analysis: In-depth Comparison from Interface to Performance
Control interface type: Determines the difficulty of system integration.
Pulse interface (general type): Supports AB phase pulses, forward and reverse pulses, etc., compatible with most PLCs and motion controllers, suitable for simple single-machine equipment.
Bus interface (high-performance): EtherCAT, Profinet, Modbus TCP, etc., supports multi-axis synchronous control (deviation < 1μs), suitable for high-speed and high-precision scenarios.
Analog interface (economical type): Receives 0-10V or 4-20mA signals, low cost but weak anti-interference ability, suitable for scenarios with low real-time requirements.
Encoder compatibility: Match the motor feedback element
The driver should support the encoder type of the motor (incremental, absolute, resolver), for example:
Incremental encoders (such as 2500 lines) are suitable for general positioning and require the driver to support differential input (anti-interference);
Absolute encoders (such as 17 bits) are used for power-off position memory (such as elevator door machines) and require the driver to have battery backup or multi-turn counting function.
Protection functions: The “safety valve” to avoid equipment damage
Basic protection: Overvoltage (such as DC bus voltage > 400V alarm), overcurrent (> 200% of rated current, output is blocked), overheat (temperature > 80℃, shutdown).
Advanced functions: Misalignment detection (preventing position deviation due to sudden load changes), mechanical resonance suppression (reducing vibration through automatic notch filter, such as machine tool processing vibration).
Selecting Models by Scenarios: Adaptation Schemes for Different Industries
1. Precision Processing Equipment (such as CNC machines, laser cutting machines)
Core Requirements: Nanometer-level positioning accuracy, multi-axis synchronous control, strong anti-interference capability.
Recommended Solution:
Bus-type drivers (such as Panasonic MINAS A6, Siemens S120) + absolute value encoder motors, supporting EtherCAT bus (cycle ≤ 100μs), achieving ±1μm positioning accuracy.
Optional: Regenerative braking unit (for handling energy feedback during frequent acceleration and deceleration) to prevent excessive bus voltage.
2. Industrial Robots (SCARA, six-axis mechanical arms)
Core Requirements: High dynamic response (speed loop bandwidth > 1kHz), low inertia matching, high integration.
Recommended Solution:
Compact drivers (such as Inovance IS620N, Delta ASDA-A3), supporting brake control and multi-turn absolute value encoders, combined with harmonic reducers to achieve ±0.1mm repeat positioning accuracy.
Choose drivers that support seamless switching between “position / speed / torque” modes to meet the demands of grasping (torque control), handling (speed control), and positioning (position control) in various working conditions.
3. Intelligent Logistics Equipment (AGVs, sorting machines)
Core Requirements: Wide voltage input (DC24V~72V), vibration resistance, support for CAN bus networking.
Recommended Solution:
DC servo drivers (such as KEB F5, Leisai DM series), supporting battery power supply (with surge protection design), IP65 protection level suitable for warehouse dust environments.
Configure anti-jamming function (automatically stop when load changes suddenly) to protect the AGV drive wheel motor from damage.
4. New Energy Equipment (lithium battery winding machines, photovoltaic string welding machines)
Core Requirements: High-speed response (speed fluctuation < 0.05%), high-precision tension control, support for Ethernet IP protocol.
Recommended Solution:
Servo drivers with built-in tension control algorithms (such as constant tension mode), combined with magnetic powder clutches or torque sensors, to achieve ±1% tension accuracy in lithium battery electrode sheet coating.
Select drivers with dual encoder interfaces (main encoder + auxiliary encoder) for real-time monitoring of roll diameter changes and dynamic adjustment of torque.
Summary: Make the Drive the “Best Partner” of the Servo System
The essence of selecting a servo drive is to “match the control accuracy to the working condition requirements and balance the power configuration between cost and performance”.
The stability of industrial automation equipment is of paramount importance. It is better to spend an extra 10% of the budget on the drive selection to avoid production losses caused by insufficient control accuracy. Only by considering the actual load, operating frequency and precision requirements of the equipment can a drive that truly “understands” the motor be selected, making the automation system run more efficiently and reliably.