Frequency converters are core motor speed control equipment in both industrial and civilian fields. Their core value lies in enabling motors to operate as needed by adjusting power supply frequency/voltage, while simultaneously serving three key functions: energy saving, protection, and precise control.
The frequency converter mainly consists of rectifier unit, filter unit, inverter unit, braking unit, driving unit, detection unit, microprocessor unit, etc.The rectifier unit converts AC to DC, the filter unit smooths the DC voltage, and the inverter unit converts DC back to AC with adjustable frequency and voltage, which supplies power to the motor.
With various frequency converters available in the market, it can be overwhelming to choose one with good cost performance. Let’s learn how to select the frequency converter we need.
| Load Type | Constant Torque Load | Variable Torque Load | Constant Power Load (CPL) |
| Scope of Application for Machinery | Conveyor belt、Mixer、 Crane | Centrifugal machinery such as fans, pumps, etc. | Cutting Machine Tools)、Wind Turbine/Wind Generator) |
| Advantage | With excellent low-speed high-torque output capability | Energy-saving optimization function | Constant power control mode needs to be considered. |
| Rated power | Rated Current | Nominal voltage |
| The frequency converter power should be slightly greater than or equal to the actual operating power of the motor. | The rated output current of the frequency converter shall be greater than or equal to 1.1 times the rated current of the motor. | Must match the voltage on the motor nameplate exactly |
| Control Mode | Communication Interface | Built-in function/features |
| Economic V/F control mode、Open-loop vector control system、Closed-loop vector control technology | When integrating PLC and DCS systems, select models with corresponding communication interfaces such as Modbus, Profinet, etc. | PID control, multi-speed operation, built-in braking unit, etc., can be selected based on application requirements. |
| Protection Level | Ambient temperature | Altitude |
| Select IP20 for control cabinets in normal environments, and IP54/IP55 or higher for harsh environments. | Operation outside the range of -10°C to 40°C requires derating or selection of wide-temperature models. | For distances exceeding 1000 meters, de-rating operation is required. Please refer to the frequency converter manual for the de-rating curve. |
Built-in protection features，. Place special emphasis on safety to prevent accidents
| Overload Capacity | Protective function |
| Typically, a 150% rated current is required for 60 seconds to meet load starting and short-term overload requirements. | Perfect overcurrent, overvoltage, overload, overheating, short circuit, and phase loss |
Here are some pictures of frequency converters for your reference.
Under non-human and improper use circumstances, our products are warrantied for one year, providing you with ultimate after-sales service.
| FAQ section | Reason | Solution |
| Motor won’t start/uneven rotation speed | Control signal lost, parameter setting error, terminal connection error | Check if the control signal is normal, verify the parameters, and reconfirm the wiring. |
| Operating vibration/noise | Carrier frequency too low.Motor mechanical failure.Inverter output harmonic interference | Increase the carrier frequency, inspect and lubricate/replace the motor bearings.Installing output reactors for harmonic suppression |
| The energy-saving effect is not obvious | The load rate has been consistently above 80% for an extended period, indicating improper parameter settings. | Optimize the V/F curve for fan/pump loads to ensure the frequency converter operates within the speed regulation range, avoiding high-frequency output maintenance during light loads. |
| Display abnormal/No output | Control panel failure, power board damage, parameters not reconfigured after factory reset | Replace the control panel for testing, check if the power board fuse is blown, and reset the core parameters. |
The above statement is for reference only.
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