What Are the Core Parameters of General-Purpose Frequency Converters?

The core parameters of general-purpose frequency converters are the key basis for selection, commissioning, and load matching. They are mainly divided into five categories: 電気 parameters, control performance parameters, protection function parameters, communication and expansion parameters, and physical environment parameters. Each category of parameters directly determines the adaptability and operational stability of the frequency converter.

1. Core Electrical Parameters

These parameters form the basis for matching the frequency converter with the power grid and motor, and must be strictly consistent with the load.

1. Input Voltage/Frequency

意味: The voltage level and frequency of the power grid connected to the frequency converter. Common specifications include 380VAC three-phase, 220VAC single-phase/three-phase, with a universal frequency of 50/60Hz.

Significance for Selection: Must match the on-site power grid; さもないと, the frequency converter may fail to start or even burn out.

2. Rated Output Current/Power

意味: The maximum output current (unit: あ) that the frequency converter can withstand during long-term stable operation, corresponding to the power of the drivable motor (unit: kW). The rating is specified under AC-3 load type and 40℃ ambient temperature.

Significance for Selection: The core selection indicator. The rated output current of the frequency converter must be ≥ the rated current of the motor (と 10% マージンが確保されている). Power is for reference only (affected by voltage).

3. Output Frequency Range

意味: The adjustable output frequency range of the frequency converter. The conventional range for general-purpose models is 0~50Hz/0~60Hz, while high-end models can reach 0~400Hz.

Significance for Selection: Determines the speed regulation range of the motor. 例えば, fans and water pumps require speed regulation in the range of 5~50Hz, and spindle motors need high-frequency operation of 0~200Hz.

4. 過負荷容量

意味: The capability of the frequency converter to bear over-rated current for a short time. Common specifications are 150% of rated current for 60s (for general loads) そして 180% of rated current for 3s (for heavy loads).

Significance for Selection: Matches the motor starting impact or load fluctuations. 例えば, heavy-duty equipment such as compressors and mixers require models with high overload capacity.

5. Carrier Frequency

意味: The switching frequency of the PWM wave output by the frequency converter, generally ranging from 2~16kHz.

Significance for Selection: The lower the frequency, the lower the heat generation and the higher the efficiency of the frequency converter, but the louder the motor operation noise; the opposite is true for higher frequencies. Adjustments need to be made according to on-site noise requirements.

1. Control Performance Parameters

These parameters determine the speed regulation accuracy and torque characteristics of the frequency converter, adapting to the control requirements of different loads.

1. Control Method

Mainstream control methods for general-purpose models:

V/f Control: Voltage is adjusted in proportion to frequency. It features a simple structure and low cost, suitable for variable torque loads such as fans and water pumps.

Sensorless Vector Control: No encoder is required, and it can achieve high torque output at low speeds (例えば, 150% of rated torque at 0.5Hz). It is suitable for constant torque loads with high torque requirements (例えば, conveyor belts, mixers).

Vector Control with Sensor: Requires a motor encoder, providing the highest control accuracy (speed fluctuation ≤ ±0.5%), suitable for high-precision speed regulation scenarios (例えば, machine tool spindles).

2. Low-Frequency Torque Characteristics

意味: The percentage of torque output by the frequency converter at low frequencies (例えば, 0.5Hz, 1Hz), which is the core indicator for measuring vector control performance.

Significance for Selection: Directly determines whether the motor has sufficient torque at low speeds. 例えば, elevator door motors and hoisting equipment require high torque startup at low frequencies.

3. Speed Regulation Accuracy

意味: The deviation rate between the actual output speed and the set speed of the frequency converter. The accuracy of V/f control is about ±5%~±10%, that of sensorless vector control is about ±1%~±3%, and that of vector control with sensor can reach ±0.1%.

4. Acceleration/Deceleration Time

意味: The time required for the frequency converter to rise from 0Hz to the rated frequency (acceleration) or drop from the rated frequency to 0Hz (deceleration), with an adjustable range generally of 0.1~3600s.

Significance for Selection: Needs to be adjusted according to load inertia. Loads with large inertia (例えば, centrifuges) require extended acceleration and deceleration times to avoid overcurrent tripping.

Ⅲ. Protection Function Parameters

These parameters ensure the safe operation of the frequency converter and motor, and are indispensable.

1. Core Protection Types

Overcurrent Protection: Limits the output current to not exceed the overload capacity, preventing the burnout of frequency converter modules.

過負荷保護: Monitors the motor operating current, and triggers an alarm and shutdown in case of continuous overload (the protection curve can be set to match the thermal characteristics of the motor).

Overvoltage/Undervoltage Protection: The frequency converter shuts down for protection when the input voltage exceeds 110% or falls below 85% of the rated value.

Phase Loss Protection: Monitors the three-phase input/output current, and triggers an alarm and shutdown when any phase is missing.

Motor Thermal Protection: The rated power of the motor is set through parameters, and the frequency converter simulates the motor heating state to prevent motor burnout due to overload (replacing the external thermal relay).

2. Protection Action Modes

Optional modes include alarm prompt, free stop, and deceleration stop, which need to be set according to on-site safety requirements (例えば, hoisting equipment should adopt deceleration stop to prevent heavy objects from falling).

1. Communication and Expansion Parameters

These parameters determine the system integration capability of the frequency converter, adapting to the networking requirements of automated production lines.

1. Communication Protocols

General-purpose models are standard-equipped with Modbus RTU, while mid-to-high-end models support industrial Ethernet protocols (Profinet, EtherNet/IP, Modbus TCP).

Significance for Selection: Enables remote control and data monitoring of the frequency converter with PLCs, touch screens, and upper computers.

2. I/O Terminal Configuration

Digital input terminals: Used for connecting external start-stop and multi-speed control signals, with a conventional configuration of 6~8 channels.

Digital output terminals: Used for outputting status signals such as operation, fault, and frequency arrival, with a conventional configuration of 2~4 channels.

Analog input/output terminals: Used for connecting external analog signals such as potentiometers and pressure sensors, with a conventional configuration of 2 input channels and 1 output channel.

3. Compatibility with Expansion Accessories

Supports external connection of braking units, input/output reactors, and EMC filters to improve power grid quality, reduce harmonics, and handle regenerative electric energy.

1. Physical and Environmental Parameters

These parameters determine the installation method and applicable environment of the frequency converter, affecting the service life of the equipment.

1. 設置方法

General-purpose models are standard-equipped with 35mm DIN rail mounting, while high-power models (≥15kW) support wall-mounted installation.

2. Protection Class

The conventional class is IP20 (suitable only for cabinet installation, preventing finger contact). Some models offer an optional IP54 class (dustproof and waterproof, suitable for on-site installation).

3. Environmental Parameters

Operating temperature: -10℃~40℃ (derating is required when the temperature exceeds 40℃, と 2% derating for every 1℃ increase).

Storage temperature: -40℃~70℃.

湿度: 5%~95% (no condensation).

高度: ≤1000m (derating is required when exceeding 1000m, と 10% derating for every 1000m increase).