Common parameter settings for frequency converter

Frequency inverters play an important role in the industrial applications as the driver for adjusting the speed ,soft starting and the key point is saving the energy.

There are usually dozens and even hundreds of parameters of VFD. However, most applications just need to use the factory default value.

Some applications need to set parameter according the site machine.

The common parameters need to set as below:

1. The motor parameters

The parameters can be set in the inverter according to the rated voltage and rated current on the motor nameplate.

1).Running direction: mainly used to set whether to prohibit reverse rotation.

2)Stop mode: used to set whether to stop by braking or stop freely.

3) Voltage upper and lower limits: set the limit according to the motor voltage of the equipment to avoid burning the motor.

2. Acceleration and deceleration time

1) Acceration time: The acceleration time is the time from its starting frequency to the operating frequency.

2) Deceleration time: The time required for the motor to stop from the operating frequency can be set.

Requirements for setting the acceleration time: Keep the acceleration current below the overcurrent capacity of the inverter and also the overcurrent does not cause the inverter to trip due to stalling.

The key points for setting the deceleration time : Prevent the smoothing circuit voltage from being too large, and do not cause the regeneration overvoltage to stall and cause the inverter to trip.

The acceleration and deceleration time can be calculated according to the load, but in debugging, it is often adopted to set a longer acceleration and deceleration time according to the load and experience, and observe whether there is an overcurrent or overvoltage alarm by starting and stopping the motor. Then gradually shorten the acceleration and deceleration setting time with the principle of no alarm during operation.Repeat the operation several times to determine the best acceleration and deceleration time.

3. Torque compensation

Torque compensation is a method of increasing the low frequency range F/V to compensate for the torque reduction at low speed caused by the stator winding resistance of the motor. When set to automatic, the voltage during acceleration can be automatically increased to compensate for the starting torque, so that the motor can accelerate smoothly. If manual compensation is used, the best curve can be selected through experiments based on the load characteristics, especially the starting characteristics of the load. For variable torque loads, if the selection is inappropriate, the output voltage at low speed will be too high, which will waste electric energy, and even the current will be large when the motor starts with load, and the speed will not increase.

4. Frequency setting signal

This function is only valid when the frequency is set with an external analog signal. It is used to make up for the inconsistency between the external setting signal voltage and the voltage inside the inverter (+10v). At the same time, it is convenient to select the analog setting signal voltage. When the analog input signal is the maximum (such as 10v, 5v or 20mA), calculate the frequency percentage that can output the F/V graph and set it as a parameter. If the external setting signal is 0-5v and the inverter output frequency is 0-50Hz, then set the gain signal to 200%

5. Control model

It is also called acceleration and deceleration curve selection. Generally, frequency converters have three types of curves: linear, nonlinear and S. Usually, linear curves are selected; nonlinear curves are suitable for variable torque loads, such as fans.

S curves are suitable for constant torque loads, and their acceleration and deceleration changes are relatively slow. When setting, you can select the corresponding curve according to the load torque characteristics.

6. Frequency

The upper and lower limits of the inverter output frequency.

The frequency is to prevent misoperation or failure of the external frequency setting signal source, which may cause the output frequency. This function can also be used for speed limiting. For example, some belt conveyors, because there are not too many conveyed materials, can use inverter drive to reduce the wear of machinery and belts, and set the upper limit frequency of the inverter to a certain frequency value, so that the belt conveyor can run at a fixed, lower working speed.

1) Panel speed regulation: The frequency can be adjusted through the buttons on the panel.

2). Sensor control: The frequency can be controlled by the voltage or current change of the sensor as a signal input.

)Communication input: Control its frequency with the host computer such as PLC.

7. Overheating protection

This function is set to protect the motor from overheating.

It is the CPU in the inverter that calculates the temperature rise of the motor based on the operating current value and frequency, thereby performing overheat protection.

This function is only applicable to "one-to-one" occasions, while in "one-to-many" situations, thermal relays should be installed on each motor. Electronic thermal protection setting value (%) = [motor rated current (A) / inverter rated output current (A)] × 100%