As a critical component of drive systems, servo motors must undergo systematic testing to ensure their torque, precision, and response speed meet operational requirements. Whether for inspecting new equipment against servo motor performance testing standards, troubleshooting issues with no-load test methods, or optimizing parameters through load characteristic analysis, a structured testing process is essential to avoid inefficiencies caused by “带病运行” (带病运行，operating with defects). This guide breaks down 8 key tests, from basic tool preparation to advanced instrument applications, to help you accurately assess servo motor performance.
Preparations: Tools and Environment Setup
1.1 Essential Tools
Multimeter/Power Meter: Measures input voltage, current, and power factor (verifies rated power matching).
Tachometer/Encoder Tester: Accuracy ≥0.1%FS (checks rotational stability and encoder signal quality).
Vibration Meter/Sound Level Meter: Vibration ≤1.5mm/s (ISO 1940 standard), noise ≤65dB (no-load condition).
Infrared Thermometer: ±2℃ precision for temperature rise tests (monitors winding and bearing temperatures).
1.2 Testing Environment Requirements
Power Stability: Voltage fluctuation ≤±5%, frequency 50/60Hz±1% (prevents grid interference).
Mechanical Installation: Use rigid couplings (coaxiality error <0.05mm) to minimize transmission backlash.
Control Platform: Pair with compatible drives and software (e.g., Mitsubishi MR Configurator2, Siemens SINA_POS) for real-time waveform monitoring.
2. 8 Core Tests: From Static to Dynamic Evaluation
2.1 No-Load Start Characteristic Test – Detect Early Issues
Method: Set drive to speed mode (500rpm), record start-up current via PC.
Key Indicators:
Peak start current ≤3x rated current (excessive current may indicate bearing jams or winding faults).
Speed rise time <0.2s (for 2000rpm motor), overshoot <5%.
Case: A servo motor showed ±15% current fluctuation during startup, traced to mild rotor magnet demagnetization.
2.2 Rated Speed Stability Test – For Speed Control Scenarios
Tools: High-precision encoder (≥2500 lines) + speed loop waveform software.
Procedure:
① Run at rated speed (e.g., 3000rpm) for 10 minutes.
② Calculate speed = [(Max – Min speed)/Rated speed] × 100%.
Standards:
Pulse drives: Variability ≤0.1%.
Bus drives (e.g., EtherCAT for CNC machines): Variability ≤0.05%.
2.3 Positioning Accuracy & Repeatability Test – Critical for Machining Quality
Scenario: 20mm positioning (1000 pulses) in position control mode.
Tools: Laser distance meter (±0.02mm) or optical grating.
Steps:
① Perform 50 cycles, record position deviation.
② Positioning accuracy = average deviation (ideal ±0.05mm).
③ Repeatability = max deviation – min deviation (ideal ≤0.03mm, ≤0.01mm for robot joints).
Note: Disable “position smoothing filter” to avoid algorithmic masking of real errors.
2.4 Torque-Speed Characteristic Test – Verify Load Adaptability
Equipment: Magnetic particle brake/dynamometer (rated torque ≥1.5x motor max torque).
Key Curves:
Constant Torque Region: Speed drop ≤5% at rated torque.
Constant Power Region: Torque decreases linearly with speed; power fluctuation ≤±3%.
Case: A lithium battery winder motor showed speed drop at 80% load, resolved by adjusting drive current loop gain.
2.5 Temperature Rise & Thermal Test – Evaluate Long-Term Reliability
Measurement Points: Stator winding (PT100 sensor), bearing housing, drive heat sink.
Conditions: Run at rated load for 2 hours, record data every 10 minutes.
Standards:
Winding temperature rise ≤80K (Class B insulation), bearing temperature ≤70℃.
Drive case temperature ≤55℃ (at 25℃ ambient); check fan if >65℃.
Advanced Tests: Dynamic Response & Fault Simulation
3.1 Acceleration/Deceleration Test – For High-Frequency Start/Stop
Method: 0-2000rpm in 0.5s, record speed loop step response.
Key Parameters:
Rise time <0.3s, settling time <0.5s (overshoot <10%).
Jerk value (jerk) ≤10000rad/s³ (reduces mechanical shock for index tables).
3.2 Electromagnetic Interference (EMI) Test – Ensure Stability in Harsh Environments
Interference Setup: Place a 10kHz carrier frequency inverter ≤30cm from motor cables.
Checks:
Encoder signals: Oscilloscope to monitor A/B phases; ≤1 false pulse/min.
Positioning deviation increase ≤10% (合格，pass); >20% requires shielding or ferrite cores.
3.3 Fault Simulation Test – Validate Protection Mechanisms
Test Items:
Overvoltage: Trigger alarm within 20ms at 420V (220V drive).
Overload: Stop within 30s at 150% rated torque (IEC 61800-3 compliant).
Step Loss: Detect position deviation within 50ms under 200% instantaneous load.
Test Report & Troubleshooting
4.1 Standard Report Template
Include test environment, instrument specs, raw data tables, waveform graphs, and recommendations.
4.2 Common Issue Diagnosis
Large Position Deviation: Check encoder wiring → drive gain parameters (P value too high) → mechanical backlash (>0.05mm).
High-Speed Noise: Inspect bearing preload (uneven resistance during manual rotation) → rotor dynamic balance (residual unbalance >5g·cm)
Data Comparison
Compare with the motor manual’s “typical performance curves”; trigger deep inspection if deviations exceed 15%.
Conclusion: Optimize Performance Through Precision Testing
Servo motor performance testing is not a one-time task but a lifecycle process spanning selection, debugging, and maintenance. By identifying manufacturing defects via no-load tests, validating load compatibility through torque tests, and refining protection mechanisms via fault simulations, you ensure stable operation in precision machining, high-speed sorting, and dynamic response scenarios. Maintain a “motor health record” to track trends and predict wear, making testing a critical tool for reliable automation.
(Note: Testing details may vary by brand; consult drive manuals or manufacturer support for customized solutions.)