1 Overview
In my country, most communication equipment uses DC power supply via switching power supplies. For safety and reliability reasons, the switching power supply system employs redundant rectifier modules, and the reserved battery charging capacity is not used during normal operation. This results in the rectifier modules operating at low load rates for extended periods, leading to low conversion efficiency and significant energy waste. Currently, major communication power supply suppliers are strengthening their technological research and development efforts, increasing investment in energy-saving and environmentally friendly designs, and continuously improving the conversion efficiency and reducing the power consumption of communication switching power supply systems through technological innovation. Among these innovations, the switching power supply rectifier module hibernation technology is a recently developed, safe, reliable, and easy-to-implement energy-saving technology.
2. Energy-saving principle of switching power supply hibernation
The energy consumption of a switching power supply rectifier module includes three parts: output power consumption, load loss, and no-load loss. Output power consumption is determined by the load current and cannot be reduced. Load loss depends on the efficiency of the rectifier module. When the load rate is within a reasonable range (40% to 80%), the efficiency is high, and load loss can be reduced by improving the module's efficiency. No-load loss is caused by the load not reaching the rated capacity and can be reduced by decreasing the number of rectifier modules or increasing the load rate.
The rectifier module sleep technology of switching power supply compares the load current with the actual number and capacity of the modules in the system, and automatically adjusts the number of working rectifier modules through intelligent "soft switching" technology, so that some modules are put into sleep mode, and the rectifier modules are adjusted to work at the optimal load rate, thereby reducing the system's load loss and no-load loss and achieving energy saving, as shown in Figure 1.
The number of rectifier modules in sleep mode can be dynamically adjusted according to load changes. When the load increases to a certain value, the sleep modules can be automatically woken up to ensure the overall output capacity. Simultaneously, the sleep time and sequence of the rectifier modules can be set via software, allowing each module to take turns sleeping, maintaining an average operating time for each module and improving their lifespan.
When using switching power supply module hibernation energy-saving technology, necessary safety measures must be taken to ensure reliable system operation under special circumstances. For example, the system should ensure that at least two rectifier modules are working. When the system experiences rectifier module failure, controller malfunction, mains power abnormality, or battery equalization charging, the system should automatically cancel the module hibernation function; when the abnormal situation disappears and the system is in float charging state, the module hibernation function should be restarted to ensure the safe and stable operation of the system.
3. Energy-saving effect analysis
3.1 Test Cases
In June 2008, a sleep-time energy-saving test was conducted on the switching power supplies of two mobile base stations, Qingxi and Huaji, in Chaohu. Under identical conditions, the energy consumption before and after sleep mode was compared. The switching power supply model was DUM-48/50C; the rectifier module model was DZY-48150C. The Qingxi base station had a load of 15A, two 500AH backup battery banks, and six rectifier modules. The Huaji base station had a load of 14A, two 500AH backup battery banks, and six rectifier modules.
During the testing, no adjacent rectifier modules failed in the second test. No imbalance protection was encountered in the AC power supply when multiple rectifier modules were connected. In the safety protection performance test of the switching power supply module's sleep function, when simulating abnormal conditions such as AC power outages, module failures, and battery charging/discharging, the switching power supply could temporarily disable the sleep function, ensuring the system operates safely and reliably.
3.2 Energy Saving Analysis
When the configuration capacity is fixed (e.g., 6 rectifier modules), the load factor and power saving rate are related as follows: With a fixed number of active modules, as the load current increases, the load factor increases, the number of modules entering sleep mode decreases, and the power saving and power saving rate gradually decrease. When the load current is fixed (115A), the load factor and power saving rate are related as follows: With a fixed load current, as the number of active modules increases, the number of modules entering sleep mode increases, and the power saving and power saving rate gradually increase. However, the total input power shows an upward trend. At this time, the increase in power saving is due to the increase in ineffective energy consumption of the system. Therefore, the configuration of the number of rectifier modules should be reasonably redundant, and the configuration should not be blindly increased.
Comparison of neutral current before and after hibernation: The comparison after hibernation shows that when the number of operating modules (T) is 3 (corresponding to a load current of 75A), the neutral current decreases. Otherwise, the neutral current will increase to some extent, mainly due to the three-phase imbalance caused by the single-phase power supply of the rectifier module. Rectifier modules in the three-phase power supply mode should not be affected. The increase in neutral current will have some negative impact, but the test results show that the increase is small and the negative impact is not significant.
4. Benefit Analysis
It is understood that the technical upgrade cost for the sleep function of switching power supply modules is less than 1,000 yuan. Taking 100 yuan as an example, and assuming a payback period of 3 years, the energy saving should be 10,000 ÷ 3 ÷ 365 ÷ 24 = 38W. That is, the cost can be recovered within 3 years if the input power is reduced by more than 38W before and after sleep mode. When the base station load current is above 100A, the energy saving effect is already poor, and the investment payback period is long, so it is not advisable to implement module sleep energy saving. If the load current is less than 100A, module sleep function energy saving should be adopted. When the module is configured according to the standard redundancy scheme, under various DC load conditions, the average energy saving of each base station is about 70W. Therefore, each base station can save 0.07 × 24 × 365 = 613.2 kWh of electricity per year. Based on 1,000 base stations of Anhui Mobile in the whole province, the province can save 6.132 × 104 kWh of electricity per year, saving about 5.5 million yuan in electricity.
From another perspective, module hibernation can reduce the average operating time of each module, lower the module failure rate, and extend the equipment's lifespan. This directly reduces energy consumption and labor maintenance costs, improving the investment efficiency of telecommunications companies. For example, implementing hibernation energy-saving measures for switching power supplies can save 4.38 × 10⁵ kW·h of electricity annually just from the power supply's own losses. Considering the overall scale, there are hundreds of thousands of base station power supplies currently operating in various telecom operator networks. If all of them adopted hibernation energy-saving measures, the annual electricity savings could reach hundreds of millions of kilowatt-hours, a considerable amount. Therefore, whether considering the global energy shortage crisis or the operational costs of enterprises, promoting base station switching power supply hibernation energy-saving technology is essential.
Click to download: Application of Base Station Switching Power Supply Module Sleep Technology in Energy Saving and Consumption Reduction
