Permanent Magnet Synchronous Traction Machine Energy-Saving Technology
The permanent magnet synchronous gearless traction machine (PMSM) is the most core technical solution for elevator energy saving. Compared with traditional asynchronous motors + worm gear reducers, PMSM's energy-saving advantages are: (1) Transmission efficiency: PMSM direct drive (no intermediate transmission loss) achieves 92%-95% efficiency, while worm gear transmission efficiency is only 75%-85%, an efficiency improvement of 10-15 percentage points; (2) Power factor: PMSM power factor can reach above 0.95 (asynchronous motor 0.85-0.90), reducing reactive power loss; (3) Part-load efficiency: PMSM efficiency does not drop significantly at part load (25%-75%) (still maintained above 88%), while asynchronous motor efficiency drops significantly at part load; (4) Regenerative power generation efficiency: PMSM has higher efficiency under braking power generation conditions, and with an energy regenerative inverter can feed back more electrical energy. Techno-economic analysis: taking a 1600kg/2.5m/s elevator as an example, the PMSM solution has a motor power of 11kW and annual power consumption of about 18,000 kWh; the asynchronous motor solution has a power of 15kW and annual power consumption of about 26,000 kWh. A single elevator saves about 8,000 kWh per year (about 6,400 yuan/year). The incremental cost of PMSM elevators (about 15,000-20,000 yuan/unit) can be recovered within 3-4 years.
Energy Regeneration and Energy Storage Technology
Energy regeneration technology feeds back or stores and utilizes the electrical energy generated during elevator braking, and is an important direction for elevator energy saving. Technical solutions: (1) Energy regenerative inverter: adopts four-quadrant operation technology to convert the AC power under elevator generating state into AC power of the same frequency and phase as the grid and feed it back to the grid. The harmonic content of the feedback current should meet the IEEE 519 standard (THD<5%). Typical energy-saving rate 15%-30% (the higher the lifting height and the higher the operating frequency, the more obvious the effect); (2) Supercapacitor energy storage system: stores electrical energy in supercapacitor banks during elevator braking, and the elevator preferentially draws power from the supercapacitors during motoring, with the excess portion then consumed. Supercapacitor charge-discharge cycles >500,000 times, service life >10 years. Compared with the grid feedback solution, the supercapacitor solution is not affected by grid power quality and can provide emergency power for the elevator during power outages (operating 10-20 floors). Recommended solution: supercapacitor energy storage + energy regenerative inverter combination, with a comprehensive energy-saving rate of up to 30%-40%.
Standby Energy Consumption Optimization and Intelligent Management
The proportion of elevator standby energy consumption in total energy consumption cannot be ignored (standby time accounts for >60% of the whole day). Optimization measures: (1) Intelligent sleep mode: when the elevator is not in use (no call signal for 3-5 minutes), it automatically enters sleep state, turning off car lighting (retaining emergency lighting), ventilation fans, and displays, while the traction machine and inverter enter standby mode. Wake-up time does not exceed 3 seconds. A single elevator can save about 1,200-1,800 kWh of standby power consumption per year; (2) Time-of-use operation strategy: automatically adjust the number of operating elevators according to hotel occupancy rate and usage demand in each period. During low-peak periods (0:00-6:00 a.m.), only 2-3 elevators operate, and the rest enter deep sleep (can be awakened); (3) In-car equipment energy saving: LED lighting (power consumption 30-60W, traditional fluorescent lamps 80-120W), inverter air conditioning (cooling capacity 1-2kW, automatically adjusting power according to the number of passengers). (4) Lighting sensing control: automatically reduce illuminance to 50lx when the car is unoccupied (safety lighting only), and restore to 150lx when occupied.
Green Lubrication and Application of Environmentally Friendly Materials
Elevator environmental protection practices include the use of environmentally friendly materials and the reduction of hazardous substances. Specific measures: (1) Biodegradable lubricating oil: lubricating oil used for elevator guide rails and guide shoes is recommended to adopt plant-based ester lubricating oil (such as rapeseed oil or sunflower oil base oil + environmentally friendly additives), with a biodegradation rate of over 90% (28 days), harmless to the environment and human body. Performance can meet guide rail lubrication requirements (friction coefficient ≤0.15, operating temperature -10 to 60 degrees); (2) Asbestos-free brake materials: brake pads adopt carbon fiber reinforced composite materials or ceramic matrix composite materials to replace traditional asbestos materials, with stable friction coefficient (0.35-0.45) and wear resistance superior to asbestos materials. The EU has fully banned asbestos materials (REACH regulation), and China is also gradually implementing restrictions; (3) Halogen-free low-smoke flame-retardant cables: elevator traveling cables adopt low-smoke zero-halogen (LSZH) material, with low smoke generation and no halogen gas release during combustion, meeting the GB/T 18380 standard; (4) Environmentally friendly coatings: car decoration coatings adopt water-based environmentally friendly coatings or powder coating (VOC-free or extremely low VOC content).