China Home Elevator manufacturer introduced why elevators generate electricity?
We can simply understand the elevator as a fixed pulley block with the car and counterweight suspended at both ends. The traction machine acting as a pulley is actually an electric motor. In the working state of the elevator, the load is driven by the traction machine to perform work, completing the process of mutual conversion of mechanical energy and electrical energy.
When the weight of the elevator car is less than the weight of the counterweight, the traction machine generates electricity when the elevator moves up and consumes electricity down; otherwise, it consumes electricity up and down to generate electricity. When the elevator goes down under heavy load and goes up under light load, the generated mechanical energy will also be converted into DC electric energy through the traction machine and the inverter. These excess energy are temporarily stored in the capacitor of the inverter's DC circuit. As the elevator working time continues, the electric energy and voltage in the capacitor are getting higher and higher. This is like the water level in a pool is getting higher and higher. If released in time, it will overflow, causing over-voltage faults and stopping the elevator.
How to release the electric energy in the capacitor? The most common method is to use an external heating resistor to convert electrical energy into heat and emit it. This method is very inefficient and has a great impact on the surrounding environment. In order to dissipate heat in the computer room, air conditioning and fan equipment must be installed. In some cases, the power consumption of the air conditioner to cool the machine room even exceeds the elevator itself.
The PROSPECT elevator electric energy feedback device can automatically detect the voltage and frequency of the inverter and the power supply network, and invert the electric energy stored in the DC circuit into AC with the same frequency and phase as the grid voltage. The electrical energy originally consumed on the braking resistor is fed back to the local power grid for use by the peripheral equipment of the local area network without polluting the power grid. The energy conversion rate of the PROSPECT elevator electric energy feedback device exceeds 97%, and the energy saving rate can reach 15-45%. The higher the floor, the greater the power, the more frequent the use, and the better the energy saving effect. It is very suitable for high-rise and high-speed elevators.