Variable frequency motor no-load test run - Solutions - Huaqiang Electronic Network

PESD1CAN Electrostatic Protection SOT23-3 24V Bidirectional

Photocoupler

When the inverter motor runs under no load, it's important to set the power and number of poles for the variable frequency motor. The operating current of the inverter should be taken into account carefully. You should also configure the maximum output frequency, base frequency, and torque characteristics of the inverter. General-purpose inverters usually come with multiple V/f curves, allowing users to choose the most suitable one based on their application. For fan or pump loads, it's recommended to set the inverter's torque control mode to variable torque and torque reduction. To enhance low-speed performance during startup, ensure that the motor can provide enough torque to meet the load requirements. Adjusting the starting torque accordingly will help improve the system’s efficiency.

In an asynchronous motor variable frequency speed control system, torque control is more complex. At low frequencies, resistance and leakage reactance have a significant impact. If the V/f ratio remains constant, the magnetic flux decreases, which reduces the motor's output torque. To counter this, voltage compensation is typically applied at lower frequencies to increase the torque. This compensation is often done manually by the user, depending on the inverter model and application needs.

Set the inverter to its built-in keyboard operation mode. Press the run and stop buttons to check if the motor starts and stops correctly. It's essential to understand the protection codes triggered during faults. Monitor the factory settings of the thermal protection relay and adjust the overload protection threshold if needed. Users can configure the inverter's electronic thermal relay function according to the manual. If the inverter's output current exceeds its allowable limit, the overcurrent protection will shut down the output. Therefore, the maximum setting of the electronic thermal relay should not exceed the inverter’s maximum output current capacity.