The configuration parameters of inverters are quite complex, with each parameter having a specific adjustable range. If the inverter is mainly used to drive inductrial motor, it is also named Variable Frequency Drive (VFD). In practical applications, improper parameter settings can lead to abnormal inverter operation. Therefore, the primary task in inverter debugging is to ensure all parameters are correctly configured. To assist in this process, we have summarized 16 fundamental inverter parameter setting methods for reference.
Inverters support multiple control modes, including speed control, torque control, and PID control. After selecting a control mode, static or dynamic identification is typically required to optimize system performance and ensure precise, stable operation.
• Speed Control: Adjusts motor speed based on the set value.
• Torque Control: Maintains constant motor output torque.
• PID Control: Compares actual and desired outputs to dynamically adjust control parameters for higher precision.
Identification Process:
• Static Identification: Conducted at standstill to determine basic system parameters.
• Dynamic Identification: Performed during operation to capture real-time system characteristics.
This refers to the lowest stable speed at which the motor can operate continuously.
• Risks of Low-Speed Operation:
♦ Poor heat dissipation, leading to motor overheating or burnout.
♦ Increased cable current, causing excessive heat generation.
• Setting Consideration: Ensure the motor and cables operate safely within thermal limits.
This defines the highest speed the inverter can drive the motor.
• Standard inverters typically support up to 60Hz, while high-performance models may reach 400Hz.
• Risks of High-Speed Operation:
♦ Excessive bearing wear.
♦ Rotor damage due to centrifugal forces.
• Setting Guideline: Match the motor’s rated speed and mechanical limits.
Affects inverter and system component heating.
• Higher Carrier Frequency:
♦ Increases high-frequency harmonics.
♦ Raises motor, cable, and inverter temperatures.
• Long Cable Impact: Greater resistance leads to energy loss as heat.
• Optimization: Adjust based on cable length, motor cooling, and thermal load.
Critical settings include power, current, voltage, speed, and maximum frequency, derived from the motor nameplate.
• Purpose: Ensures accurate control and prevents motor damage.
• Verification: Cross-check with motor specifications for consistency.
Avoids resonance or compressor surge at specific frequencies.
• Application:
♦ Sets a frequency band to bypass critical speeds.
♦ Essential for high-inertia systems and compressors.
• Acceleration Time: Duration for frequency to rise from 0 to maximum.
• Deceleration Time: Duration for frequency to drop to 0.
• Setting Method:
♦ Start with longer times.
♦ Gradually reduce while monitoring for overcurrent (acceleration) or overvoltage (deceleration) alarms.
Compensates for low-speed torque reduction by increasing V/f ratio at low frequencies.
• Modes:
♦ Auto: Adjusts voltage during acceleration.
♦ Manual: Custom compensation curves based on load tests.
• Caution: Excessive boost can cause high current at startup or energy waste.
Prevents motor overheating by monitoring current and frequency.
• Setting:
♦ Single Motor ("1-to-1"): Direct protection via inverter.
♦ Multiple Motors ("1-to-N"): Requires external thermal relays per motor.
Restricts output frequency to prevent overspeed or underspeed due to faults or misuse.
• Application Example: Limiting conveyor belt speed to reduce wear.
Adjusts the minimum output frequency when using external analog signals (e.g., 0V ≠ 0Hz).
• Usage:
♦ Corrects offset (e.g., setting –xHz to achieve 0Hz output).
♦ Some inverters allow polarity adjustment.
Aligns external analog signals (e.g., 0–5V) with the inverter’s internal reference (e.g., 0–10V).
• Example:
♦ For 0–5V → 0–50Hz, set gain to 200%.
• Drive Torque Limit: Prevents overcurrent during startup/acceleration.
• Brake Torque Limit: Controls deceleration intensity; excessive values may trigger overvoltage.
• Optimal Setting: Balance between responsiveness and protection.
Selects speed transition profiles:
• Linear: Constant rate (for steady loads).
• Nonlinear/S-curve: Smoother transitions (for sensitive loads like fans).
Enhances low-speed torque and dynamic response by decomposing stator current into magnetic field and torque components.
• Applications: High-precision machinery (e.g., CNC, textile machines).
• Slip Compensation: Corrects speed deviations under load.
Optimizes V/f mode for variable-torque loads (e.g., brushless pumps, fans).
• Principle: Reduces voltage at light loads to save energy.
• Note: Incompatible with vector control; improper use may cause trips.
Proper inverter debugging requires methodical parameter tuning based on motor characteristics and load demands. Modern inverters integrate AI diagnostics and IoT for predictive maintenance, further enhancing efficiency and reliability. Always refer to manufacturer guidelines for model-specific adjustments.
