The key factors for selecting energy feedback devices in daily industrial control use are:
Load characteristic matching
Constant torque loads (such as cranes and winches) require the selection of feedback devices with high dynamic response capabilities to ensure rapid absorption of regenerative energy.
Variable torque loads (such as fans and pumps) require adjusting the feedback power threshold based on the speed torque curve (such as the square torque characteristic).
Power and voltage levels
The rated power of the feedback device should be ≥ 1.1 times the rated power of the motor, and the bus voltage should match the grid voltage (such as 400V/660V system).
For high-power equipment (>100kW), it is recommended to use a four quadrant frequency converter that supports bidirectional energy flow.
Grid compatibility
It is necessary to detect the voltage fluctuation range of the power grid (± 20%) to ensure that the harmonic distortion rate (THD) of the feedback current is less than 5%.
Priority should be given to devices with voltage/frequency synchronization detection function to avoid feedback current and grid synchronization.
Technical classification and applicable scenarios
Type characteristics Applicable scenarios
Split type independent installation, easy to maintain, but requires additional wiring renovation projects or elevator systems with limited space
Integrated into the frequency converter, fast response and high cost for new industrial equipment (such as centrifuges)
Energy storage combined with battery pack, suitable for off grid or unstable grid scenarios without grid feedback conditions
Economic and energy-saving effect evaluation
Energy saving rate: The elevator energy feedback device can reach 17.85% -40.37%, and the investment payback period needs to be calculated based on the load rate.
Cost comparison: The price of the feedback device is about 2-3 times that of energy consumption braking, but the long-term energy-saving benefits are significant.
Key points for installation and maintenance
Heat dissipation design
High power feedback devices require forced air cooling (such as explosion-proof fans) to ensure IGBT junction temperature<125 ℃.
Reserve a heat dissipation space of ≥ 100mm inside the box to avoid heat accumulation.
Protection function
It is necessary to have overvoltage, overcurrent, overheating, and reverse connection protection for the power grid. If the bus voltage exceeds 1.2 times the effective value of the power grid, it will automatically cut off.
Suggestions for selection process
Actual load curve: Determine the peak regenerative energy through torque speed testing.
Power grid detection: Verify the harmonic content and voltage stability of the power grid.
Simulation verification: Use tools such as MATLAB to simulate the feedback current waveform and optimize control parameters.