Foreword: Large Electronics designed a lithium ion battery as emergency power supply based on the customers’ requirements of field emergency X-ray machine, field B supersonic diagnostic set, power failure emergency X-ray machine, power supply of field medical device. This battery pack applies imported chip and IFR26650 lithium iron phosphate battery with high safety performance, high consistency and long cycle life. It has MOS tube for protective and controlling management. The whole battery pack has continuous operation ability under large current. The continuous output power is 1000W. The maximum constant power is 2KW. The battery pack with UPS can supply power under emergency for most of medical devices.
I. Lithium ion battery design requirements of emergency X-ray machine:
Based on product specification and customers’ requirements, design intelligent large current lithium ion battery to match the host machine and integrate the functions of advanced safety performance, good charging and discharging performance, large current operating capacity and outstanding cycle life into the solution.
II. Lithium ion battery design scheme of emergency X-ray machine:
1）Guard plate (PCM): Design the protective circuit based on the chemical characteristics of lithium iron phosphate battery and operating characteristics of X-ray machine. Besides the proactive functions of overcharging, over-discharging, overcurrent and short circuit, it also needs to solve the problems of high-power cooling system and balance of the whole battery pack.
2）Protective circuit: it adopts imported IC and MOS, and has on line monitoring for battery functions of overcharging, over-discharging, overcurrent, short circuit, etc., which helps battery works under safe, stable and efficient circumstance.
3）Overcurrent fuse: It is designed for secondary defense. The battery pack applies large power cell with large capacity. Although battery management system has protection of overcurrent and short circuit, it still leads in protection failure when abnormal circumstance occurs. Large current is produced under output short circuit and results in danger. Therefore, there is overcurrent fuse in the scheme, so that the fuse will cut off the circuit irretrievably for abnormity protection when short circuit occurs.
4）Battery: Adopt lithium iron phosphate battery of LARGE26650/3.2V/3000mAh. The maximum charging rate of this battery is 1C, and maximum discharging rate is 2C. The battery has multiple protective functions. It has management system inside the battery to prevent safety issues of the battery.
5）The parameters of the whole battery: 38.4V/39Ah (nominal parameter: 24V80Ah). Its maximum operating current can reach 60A, and constant starting current is 100A.
6）Battery pack: The battery pack use resistance equalization inside, which can effectively deal with the capacity reduction due to the differences between single batteries and expand the cycle life as much as possible.
7）The battery pack adopts plastic holder to fix the battery, which does good to heat dissipation and safety application of the battery.
Schematic diagram of design solution