Energy - storage elevator energy saver

一． Elevator system in China

At present, the domestic elevators are usually synchronous motor or asynchronous motor with variable frequency traction, and the structure is as follows：

The energy consumption resistance is also called the brake resistance, and the regenerative energy of the motor is generally consumed through the brake resistance.
The brake resistance will produce a large number of heat sources, causing the temperature of the elevator engine room to rise.

二．Energy saving principle

1. Energy source of saving

Energy is conserved, so energy conservation is bound to have a source, and the features of the elevator work are as follows：

In general, the weight ratio of the domestic elevator is 40%--50%, and the weight of the car and counterweight is different when the elevator is running, so the gravity potential energy difference between the car and the counterweight block will happen during the upper and lower process. The difference between the potential energy needs to be supplied by the power grid, or the regenerative power is fed back to the DC end of the inverter, and it is consumed by the brake resistance.
So the source of elevator energy saving is potential energy. When we need to overcome potential energy to do work, the power grid drives the motor to work through inverter. When potential energy is working, potential energy is generated through motor regeneration, and then fed back to the DC terminal of converter.
The general practice of domestic elevator is that the energy of regenerative power is consumed by braking resistor, and then it needs to get energy from the power grid when it is used for electricity, which wastes a lot of energy of regenerative power generation.

2. Our plan

节能器内部结构图：

We design a system to recover energy quickly in the process of energy feedback, and then quickly release energy in the process of energy consumption, which saves a considerable amount of energy, that is, the principle of energy saving in our device. As the energy consumption process and the energy feedback process may be very short, it is necessary to be a fast recovery and release system.
Because of the above consideration, our system is directly connected to the DC bus of the inverter, and then the supercapacitor is used as the energy storage system. In the process of energy feedback fast charging of super capacitor, thus the energy recovery, and avoid the DC bus voltage of the inverter increases in energy consumption; using the rapid discharge of super capacitor, the injected power to the inverter DC bus, thus reducing the energy sources of electricity.

3. summary

We store the energy consumed by the brake resistance and make use of it, which is the source of energy saving.
The principle and theory of energy saving are clear.

三． Special energy saving scheme for a company Elevator

1. Internal structure of energy saving device

2. resource allocation

Reserve 2 optocoupler input signals reserve;
Reserve 2 optocoupler output signals reserve;
Reserve 2 relay relay points for backup.
Reserve RS485 or CAN communication bus standby.
Reservation for communication between the energy saving device and electric control cabinet, such as emergency use, charge and discharge control etc..

3. Connection with the elevator system

                     The part of the energy resistance below is the installed energy saving device. The high voltage end of the energy saving device is connected to the elevator frequency converter straight
The flow bus is positive, and the negative pole of the high voltage end of the energy saving device is connected to the negative pole of the DC bus.

4. Change of power supply part of elevator control cabinet

Schematic diagram of power supply for the original control cabinet：

110vdc: 2A ;   24v:1A

 Change control cabinet power supply diagram：

        After the change from the inverter DC bus power supply cabinet to take power。

四． Bi-directional DC/DC technical parameters

五． Work pattern description

     1. the working state of the elevator at the standby time
In the boost state, the supercapacitor voltage is boosted to maintain the DC bus voltage of the inverter at 600Vdc until the super capacitor voltage is undervoltage. All the power control cabinet are provided by the energy-saving device to release the super capacitor energy as soon as possible, so as to reduce the super capacitor energy demand.
2. the working state of the elevator brake runner
When the elevator is braking, the DC bus voltage of the inverter will rise, and the energy saving device will quickly absorb the regenerated hair of the traction machine
The energy of the electricity is stored in the super capacitor. The energy saving device performs strict current limiting on the side current of the supercapacitor, such as 80A, so that the charging current is strictly less than equal to 80A.
If the energy saver can completely absorb the regeneration energy, the energy saving device will maintain the DC bus voltage of the inverter at 620Vdc. If it can not be completely absorbed, the DC bus voltage of the converter will continue to rise to the threshold of the energyresistance opening voltage, and the excess energy will be consumed by the resistance.
3. working state of energy saving device for elevator
When the elevator is used for electricity, the energy saving device discharges the DC bus of the inverter, but the discharge of the supercapacitor is strictly limited.
Current, maximum no more than 80A.
If the elevator power is smaller than the energy saving device provides power, energy saving device provides all the power inverter, the DC bus voltage is maintained at 600Vdc; if the elevator power is greater than the energy saving device provides power, energy saving device provides power converter, DC bus voltage is determined by the grid voltage.
The working state of the energy saving device in 4. city power outages
When the elevator is on standby: the energy saving device provides all the power to the elevator and tells the elevator that the electricity has lost electricity and the elevator will stop.
Call the request, open the sedan door and wait for the power supply stop of the energy saving device.
The elevator runs and is braking: the energy saver continues to recover the energy and tells the elevator the electricity has lost electricity, the elevator
Will stop the call request, slow down to the nearest target station, open the sedan door and wait for the power supply stop of the energy saving device.
The elevator runs and is in electric state: the energy saving device provides all the power of 50ms time to the DC bus of the inverter.
The DC bus voltage of the converter is reduced to 500Vdc, and it tells the elevator that the electricity is out of power. The elevator should slow down immediately and park to the nearest floor, stop the call request, open the car door and wait for the power supply to stop.
No matter what the state is, the passengers do not feel a severe pause. They will not immediately feel the fear of power failure. The elevator will gradually slow down and stop, improving user experience.

六． Energy saving capacity configuration

The principle diagram of the energy saving system is as follows：

The most important part of the energy saving system is the bidirectional DC/DC, the super capacitor energy storage system. The configuration and optimization of the energy saving system is no more than the collocation of the two core components.
1. DC/DC configuration
This case selects the two-way DC/DC of 80A.
2. supercapacitor configuration
In this case, the 48V/166F supercapacitor module 3 group is selected and the charge discharge range is 70 - 140Vdc. Storage
Energy 400KJ, about 0.11KWH.
3. size and weight
Size: 450*300*1100mm (long * width * high).
Weight: 70KG.