Elevator energy-saving equipment suppliers remind you that with the development of the economy, energy demand is increasing, and energy shortage has become one of the main factors restricting the development of various fields. As an important and efficient transportation equipment in high-rise buildings, elevators have gradually become the second largest energy consuming device in high-rise buildings, second only to air conditioning electricity consumption and higher than lighting, water supply, and other electricity consumption. The energy consumption of elevator operation accounts for 20% to 50% of the building's operating energy consumption, and the energy consumption issue cannot be underestimated.
The energy consumption of elevator operation mainly includes two parts, one is the energy consumption of the traction machine dragging the elevator car and load; The other part is the energy consumption of the elevator system itself, mainly the energy consumption of the door machine system, elevator control system, electrical control circuit electrical system, elevator lighting system and ventilation system, and the efficiency energy consumption of the mechanical transmission system, car and guide rail motion pair. Research has shown that the electrical energy consumed by a traction machine dragging a load accounts for over 70% of the total electricity consumption. The use of appropriate energy-saving technologies for energy-saving treatment of elevators is an inevitable trend in the development of the elevator industry.
The Development Process and Research Status of Elevator Energy saving Technology
The application of elevators has greatly increased people's demand for energy, so from its invention to its widespread use today, the requirements for energy-saving technology have been running through it, mainly reflected in three aspects:
(1) Energy saving of elevator traction machine drive technology
There are five types of elevator traction machine drive technology, including AC asynchronous motor with gearbox transmission, AC asynchronous motor without gearbox transmission, permanent magnet asynchronous motor with gearbox transmission, permanent magnet synchronous motor with gearbox transmission, and permanent magnet synchronous motor without gearbox transmission. The PM traction machine is currently an ideal and advanced transmission method, with advantages including permanent magnet synchronous motor, no need to add gearbox lubricating oil, high power factor and operating efficiency. Due to the absence of losses during the transmission process, gear motors save about 30% energy compared to asynchronous AC motors. Its outstanding feature is that it is the only permanent magnet motor that can suppress accidents causing personal injury to passengers due to the elevator losing control and sliding during operation, and has received praise from the industry and users.
(2) Energy saving elevator control system
The development process of elevator drive control technology has started from AC asynchronous motor pole changing speed regulation to AC voltage regulation speed regulation; Moving on to variable voltage and variable frequency speed regulation. The commonly recognized best driving method is to use a combination of variable frequency and variable voltage speed regulation to control the permanent magnet synchronous traction machine [3]. By changing the input frequency and voltage of the elevator motor, the elevator speed regulation process can be achieved. The frequency and voltage ratio are controlled by a frequency converter to maintain a fixed ratio, which can smoothly adjust the speed. Compared with the previous two speed control systems, VVVF has the advantages of high efficiency, smooth speed regulation, and energy saving of over 30%. Moreover, it has the characteristics of good performance, small size, high efficiency, and comfortable ride, making it an ideal and popular speed control device.
(3) Energy saving of energy feedback system
The current energy-saving method for elevators is to feed back the electrical energy generated by the traction machine during power generation to the power grid. The current method for handling the electrical energy generated by traction machines during power generation is to connect energy consuming resistors and convert this electrical energy into heat energy to release it, in order to avoid overvoltage faults in elevators. This method not only causes energy waste, but also has adverse effects on the surrounding environment, increases the burden on the cooling system of the machine room, and has adverse effects on the entire elevator system.
The function of the energy feedback system is to convert the electrical energy on the DC bus into AC power of the same phase and frequency as the grid through an inverter, and feed it back to the grid in the high voltage range of the grid voltage.
At present, 25% to 35% of the total electricity consumption of elevators is consumed by braking resistors. Based on an energy inversion efficiency of about 85%, the energy-saving efficiency of elevator energy feedback devices is estimated to be in the range of 21% to 30%. This interval increases significantly as the elevator floor and speed increase. The elevator energy feedback grid connected system has achieved the function of "creating" energy from traditional energy saving, opening up the history of elevator energy saving.
Energy saving principle of elevator energy feedback device
The energy-saving option for elevators is variable frequency speed regulation. After starting, the elevator will exhibit the highest mechanical energy during rapid operation. After reaching the target floor, the elevator slows down and gradually stops. In the subsequent process, the elevator can release existing mechanical energy and loads. The fundamental mechanism of frequency conversion feedback is that the frequency converter can store the existing electrical energy on the DC side and then feed it back to the AC power grid. In this state, the braking resistor will no longer consume more electrical energy. The variable frequency feedback device can eliminate subtle energy consumption and completely return it to the power grid. From this, it can be seen that the frequency conversion feedback meets the energy-saving indicators and improves the overall elevator operation.