How to Choose the Right Frequency Converter？

2025-11-24 4 minutes

What is a frequency converter?

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.

Main Structure of Frequency Converter

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.

Main Types of Frequency Converters

Low-voltage frequency converters and high-voltage frequency converters are classified based on input voltage levels.
According to the frequency conversion method, they can be divided into AC-AC frequency converters and AC-DC-AC frequency converters.

Frequency converters can be classified as voltage-source inverters and current-source inverters according to the nature of DC power supply.
According to their working principles, frequency converters can be classified into V/F control frequency converter, SF control frequency converter, and VC control frequency converter, etc.

Highlight product advantages

Copper core conducts electricity with high conductivity.

Device with LCD display.

Powerful cooling design, simple and reliable operation.

User-friendly operation with wide application range.

What aspects should be considered when selecting a frequency converter?

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.

Determine the load type. Load types can be divided into constant torque load, variable torque load, and constant power load. Different machines require different selections.

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.

Determine the matching motor parameters, such as power, voltage, and current.

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

Consider the control function requirements.You need to select the control functions that meet your needs.

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.

Equipment adapts to working environment ，Select the protection level, ambient temperature, and altitude according to the equipment’s working environment.

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.

Product Material Introduction

Flame Retardant ABS Enclosure/Case：Shockproof, flame retardant, anti-aging, and corrosion resistant

Intelligent chip ： Moisture-proof and anti-static

Copper core terminal block：Instantaneous high-power current acceptance

LCD (Liquid Crystal Display)：More intuitive and more efficient

Cooling Fan ：Stabilize equipment performance, reduce noise, and enhance equipment lifespan.

After-sales service

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.