The elevator adopts the traction structure, and the balance is maintained by the counterweight block, so that the passenger car achieves smooth operation under the drag of the traction machine. The elevator has three working conditions such as standby, driving and regeneration (feedback). When the elevator is not running in a stationary state, it is in standby condition; when the elevator is in the state of heavy load upward or light load downward, the external electric energy is transformed into the potential energy of the car through the rectification and inversion of the frequency converter, the traction machine and the operation of the traction system, which is in the driving condition; on the contrary, when the elevator is in the state of heavy load downward or light load upward, the potential energy of the car is released, either through the bi-directional inverter, which will feed back the energy to the power grid, or the energy will be consumed in the braking resistor of the frequency converter, which is in the driving condition. The braking resistance of the frequency converter is regenerative (feed-back) condition.

1. Standby condition: the elevator is not working continuously, and the standby time is usually much larger than the time of running up and down of the car, so the power consumption in the standby condition is not only not negligible, but also has a considerable loss. In the standby condition, part of the power consumed by the elevator is consumed in the control and display circuits in the machine room, car and floor station, and the other part is consumed in the lighting and exhaust facilities of the car.

2. Driving condition: In the driving condition, in addition to the consumption in the standby condition, the power consumed by the elevator also includes the following aspects: one is the power consumption of the switching door; the second is the loss of the frequency conversion device, including the loss of all circuits in the main circuit from the input of three-phase power supply to the output of the inverter, including the filters, rectifiers, and inverters; the third is the loss of the traction machine, including the loss of the internal mechanical drive of the traction machine; the fourth is the loss generated by the traction system, including the loss from the control and display circuit in the machine room and car and floor station; and the other part is consumed in the lighting and exhaust facilities of the car. Fourth, the loss generated by the traction system, including from the beginning of the rotation of the traction sheave to the traction wire rope to drive the car running in the whole process of energy loss. After a series of losses, the electric energy is transformed into kinetic energy and potential energy required for elevator operation. It should be noted that the traction elevator due to the role of the “counterweight mechanism”, the power consumption under different load conditions is very different, so the energy efficiency under different load conditions varies greatly.

3. Regenerative working condition: The energy flow situation under the regenerative working condition is relatively complicated. On the one hand, the power consumption of the elevator is converted into part of the kinetic energy of the car and the load (W dynamic) through the inverter and traction machine after the opening and closing of the door motors, control and display circuits; on the other hand, the potential energy of the car and the load (W potential) is partly converted into the kinetic energy of the car and the load (W dynamic), and the other part is fed back to the inverter through the traction system and the traction machine. For the elevator with energy feedback function, the frequency converter will feed this part of energy (E back) back to the power grid through inverter and filtering, and for the elevator without energy feedback function, this part of energy will be consumed in the heat dissipation resistance of the frequency converter.