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inverter controls the motor to achieve multi-speed, which is a common motor speed control method. By setting the multi-speed parameters inside the inverter or cooperating with external control, multiple fixed speeds can be switched. The following are common methods to achieve multi-speed control:

1. The inverter has built-in multi-speed function

Many inverters have built-in multi-speed control functions, and different speeds are selected through external input signals or internal settings.

Steps:

Parameter setting:

Confirm that the inverter supports multi-speed function.

Define the frequencies corresponding to different speeds in the inverter parameter settings (such as P0.06, P0.07, etc., the specific parameters vary from brand to brand).

Input terminal configuration:

Set the input terminal corresponding to the multi-speed to the multi-speed selection function (such as DI1 and DI2 correspond to speed 1 and speed 2, respectively).

Logic combination:

Control the speed switching according to the combination of high and low levels of the terminals. For example:

DI1 = high level, DI2 = low level, output speed 1.

DI1 = low level, DI2 = high level, output speed 2.

Advantages: Simple implementation, no external complex equipment is required.

Applicable scenarios: Applicable to situations where fixed speed switching is required, such as conveyor belts, multi-pump control, etc.

2. PLC control of multi-speed

Control multi-speed through PLC (programmable logic controller) and inverter communication, suitable for more complex application scenarios.

Steps:

Communication mode selection:

Configure PLC and inverter communication mode (commonly used Modbus, Profibus, CAN, etc.).

Inverter parameter setting:

Set the control mode of the inverter to communication control.

PLC programming:

In the PLC program, write the operating frequency (register address) of the inverter through communication or select the preset frequency.

Use logical judgment to realize the speed switching conditions, such as selecting frequencies F1, F2, F3, etc. according to different conditions.

Advantages: High flexibility and easy to expand control logic.

Applicable scenarios: Applicable to complex multi-speed switching scenarios or processes that require remote control.

3. Analog control of multi-speed

By providing different analog signals (such as 0.10V or 4.20mA) to the inverter externally, its operating frequency can be controlled.

Steps:

Set the inverter input mode:

Set the frequency source of the inverter to analog signal input.

External control design:

Use a potentiometer or analog output device to provide different voltage/current signals.

Define speed range:

Set the minimum and maximum frequency values corresponding to the analog input of the inverter.

Advantages: Smooth transition, suitable for working conditions requiring continuous speed change.

Applicable scenarios: Dynamic speed regulation and stepless speed change scenarios are required.

4. Digital input + analog combination mode

Digital input is used to switch the speed mode, and analog signals are used to set the frequency value to achieve more flexible control.

Example:

Digital input DI1 = high level, corresponding to the use of speed segment 1 (fixed frequency 30Hz).

Digital input DI2 = high level, analog control speed segment 2 (dynamic speed regulation).

Application Notes

Frequency range: Make sure the set frequency range is suitable for the motor's operating requirements.

Load characteristics: The load characteristics of different speeds may be different. Adjust the motor starting parameters if necessary.

Signal interference: Avoid interference when wiring digital input or analog signals to ensure accurate control.