In the daily use of frequency converters in industrial control, the core requirements of feedback unit selection are as follows:
Load Characteristics Match
Constant torque load (such as crane, hoist): continuous feedback unit with braking torque ≥ 150% must be selected, and the power is the same as the rated power of the motor.
Variable torque load (such as fan, water pump): the power of the light-duty feedback unit can be reduced by one gear (braking torque 110%, 1/4 working system).
Impact load (e.g. mill, punching machine): two gear power increases and brake units are configured.
Power and voltage rating
Feedback unit rated power≥frequency converter power generation, the voltage level should be consistent with the input voltage of the frequency converter (such as 400V / 660V).
When using a synchronous motor, the power of the feedback unit needs to be one gear larger than the asynchronous motor.
Operating system and heat dissipation
The intermittent working system (idle ratio ≤50%) can reduce the power selection, and the continuous working system needs to be selected by 1.2 times the motor power.
High temperature environment (> 40 ℃) need to reduce the use, each increase of 1 ℃ reduction of 1%.
Technical parameters and certification requirements
Harmonic and electromagnetic compatibility
Harmonic current emission must meet IEC 61000-3-2 (THD < 5%).
Voltage fluctuation and flashing tests must meet EN 61000-3-3 (Pst≤1, Plt≤0.65).
Protection function
Need overvoltage, overcurrent, overheating protection, the motherboard voltage exceeds 1.2 times the grid voltage automatically cut off.
Isolated island detection function to ensure safe downtime when the power grid is abnormal.
Economics and installation advice
Energy Saving Benefits
Elevator feedback device can save up to 15%-45%, the investment recovery period is about 2-3 years.
High-power equipment (>100kW) prefers four-quadrant frequency converters, with significant long-term energy saving gains.
Installation and Maintenance
Compulsory air-cooled design (such as IP54 protection grade) to ensure IGBT bonding temperature < 125 ℃.
≥100mm cooling space should be reserved to avoid heat accumulation.