1. The battery requirements for the backup power supply of the mobile communication microwave transmission tower:
The signal transmission tower is mainly composed of the following parts: transmitting equipment, receiving equipment, antenna feeder system, power supply equipment, and monitoring and control equipment required to ensure the normal operation of communication lines and unmanned maintenance. In addition to the AC direct power supply drive signal tower, the power supply also includes a UPS backup power drive system to prevent the system from being unable to work due to power outages. Most of the early power supplies used lead-acid batteries as the power supply for the backup power supply. Because lead-acid is not environmentally friendly and has shortcomings such as low energy ratio, large size, and short lifespan, new or upgraded base stations are gradually beginning to use lithium-ion batteries as the power supply system of the base station's backup power supply. Based on the above problems, our customers require lithium batteries as the main power source. The backup power system can support the entire launch system to work for more than two hours after a power failure and can meet the requirements of the system for long-term work in the field.
According to the power consumption and conversion efficiency of the customer's entire transmission system, we calculated that the battery pack needs 48V 65Ah to meet the customer's working time requirements. Due to the high voltage of the entire battery, the relatively large overall battery capacity, and the relatively high ambient temperature, and to ensure the stability of the entire system, we use lithium battery cells imported from Japan in terms of lithium battery cells, which have high overall consistency. Each cell is built-in multiple protections, including an explosion-proof valve, PTC, etc.
The power supply system PCM protection system unit includes: 1 set to detect the overcharge and over-discharge protection of a single string of batteries; 2 the temperature protection, overcurrent protection, and short circuit protection of the whole group of batteries; 3 balance system between the single strings of batteries;
The battery power detection part includes a detection system and a display system. The detection adopts the method of current and voltage calculation, the display and detection accuracy is very high, and the LCD display screen dynamically and intuitively detects and displays the charging and discharging status of the battery.
2. Design scheme of back-up power battery for mobile communication microwave transmission tower:
1) Battery pack design parameters: The customer requires a 1000W AC power supply system to work for two hours. Based on the conversion efficiency and matching voltage of the UPS, we calculated the battery voltage and capacity to be 48V/65Ah, which can meet the system's full load for 150 minutes.
2) Protection Board (PCM) design parameters: with single-cell overcharge, over-discharge, temperature, overcurrent, short circuit protection, etc. The specific protection parameters are as follows:
1. Single-cell overcharge protection voltage: 3.90±0.25V
2. Single-cell overcharge recovery voltage: 3.80±0.50V
3. Single-cell over-discharge protection voltage: 2.30±0.10V
4. Single-cell over-discharge recovery voltage: 2.70±0.10V
5. Combined battery overcurrent protection value (10ms): 40±10A
6. Charging balance current: 36±10mA
7. Charge balance voltage: 3.65±25mV
8. Battery temperature protection range (recoverable): -20~60 degrees
9. The finished battery also has short-circuit protection
3) Battery power monitoring system (PCM) design function: using the intelligent dedicated chip, with LCD display: the display parameters can be set in real-time by pressing the buttons as needed. The display part includes current battery capacity, current capacity percentage, current battery voltage, Charging current, discharging current, remaining discharge time, percentage of charge (RSOC), and percentage of absolute remaining charge (ASOC).
4) Design requirements for the overall structure of the battery: Since the base station has a wide distribution area and is placed in the field, in addition to considering the insulation with the battery, it is also necessary to consider moisture-proof, not easy to deteriorate, etc., so the shell structure adopts fiberglass board as the main body. Due to a large number of battery cell combinations, isolation and heat dissipation issues need to be considered. We use battery-specific engineering plastic brackets as the main body for fixing and isolating the lithium battery pack.
5) Secondary protection: The entire battery pack is equipped with an abnormal over-current short-circuit protection fuse to prevent abnormal battery and failure of the protection board from causing excessive current. When excessive current is generated after the PCM system is abnormal, the fuse will cut off the output circuit of the entire battery pack and cannot be recovered.
6) Lithium battery cell: Using factory A-grade battery chip, 32700 lithium iron phosphate cell/32700/6000mAh/3.2V, this cell has good safety and consistency, thus ensuring the reliability of the entire battery pack.
3. The block diagram of the backup power supply design of the mobile communication microwave transmission tower:
