The inverter load operation debugging must be carried out in the following five steps.
(1) Manually operate the running stop button on the inverter panel to observe the motor running stop process and the display window of the inverter to see if there is any abnormality.
(2) If the inverter has an overcurrent protection action during the start/stop motor, the acceleration/deceleration time should be reset. The acceleration of the motor during acceleration and deceleration depends on the acceleration torque, and the frequency change rate of the inverter during the start/stop process is set by the user. If the motor's moment of inertia or load change is increased or decelerated according to the preset frequency change rate, there may be insufficient acceleration torque, which may cause the motor to stall, that is, the motor speed and the inverter output frequency are not coordinated, resulting in overcurrent or overshoot. Voltage. Therefore, it is necessary to set the acceleration and deceleration time according to the motor inertia and load, so that the frequency change rate of the inverter can be coordinated with the motor speed change rate. The reason for debugging this setting is reasonable. Firstly, the acceleration and deceleration time are selected according to experience. If there is overcurrent during the starting process, the acceleration time can be extended appropriately; if overcurrent occurs during braking, Prolong the deceleration time appropriately.
(3) If the inverter still has overcurrent protection action within a limited time, change the start/stop operation curve, such as changing from straight line to s-shaped, u-shaped line or anti-s-shaped or anti-u-shaped line. When the motor load inertia is large, a longer start/stop time should be used and the operating curve type should be set according to its load characteristics.
(4) If the inverter drives the motor to reach the preset speed during startup, there may be two reasons:
• Electromechanical resonance occurs in the system and can be judged from the sound of the motor running. The resonance point can be avoided by using the method of setting the frequency jump value (generally the inverter can set the three-level jump point). When the inverter of v/f control mode drives the three-phase asynchronous motor, the current and speed of the motor will oscillate in some frequency segments. In severe cases, the system cannot run, and even overcurrent protection occurs during the acceleration process, making the motor unable to operate normally. Start-up is more serious when the motor is lightly loaded or the moment of inertia is small. The common inverters are equipped with a frequency jump function. The user can set the jump point and the jump width on the v/f curve according to the frequency point at which the system oscillates. These frequency segments can be automatically skipped when the motor accelerates to ensure that the system can operate normally.
• The torque output capability of the motor is not enough. The factory parameters of different brands of inverters are different. The load capacity is different under the same conditions. The load capacity of the motor may be different due to different control modes of the inverter; or the output efficiency of the system Different; the load capacity will vary. In this case, the value of the torque boost amount can be increased. If it is not possible, the manual torque boost function can be used, but do not set it too large, and the temperature rise of the motor at this time will increase. If it still doesn't work, you should switch to the new control method.
(5) If the inverter also has an overcurrent protection action, try to increase the protection value of the maximum current, but you cannot cancel the protection. Leave at least 10% to 20% of the protection margin. If this action still occurs, you should replace the inverter with a larger power.