China News Service, Shanghai, May 29th, title: How does "Tianzhou-2" use electricity in space as it enters the space station era?

　　Author Guo Chaokai Zheng Yingying

　　After the successful docking of the Tianhe core cabin of the China Space Station and the Tianzhou-2 cargo spacecraft, in the combined flight mode, in order to ensure the power generation capacity of each cabin and the cargo spacecraft, the core cabin and the cargo spacecraft will be connected to the grid for power supply.

In the space station era, what are the clever ways to use electricity for the "Express Brother" Tianzhou II, which has just set foot in space?

Experts from the Eighth Academy of China Aerospace Science and Technology Corporation responsible for its power subsystem announced one by one.

"Small power and more affection": Relations between courtesy and Shang

　　The core cabin can provide up to 2000 watts of power for the cargo spacecraft.

Although compared with the “big family” of the core cabin, the power supply capacity of the cargo spacecraft is only one-third of its (core cabin), but the Chinese have been paying attention to "reciprocity" since ancient times. At critical moments, the cargo spacecraft can also provide the core cabin. About 1000 watts of power supply.

　　"The core cabin supplies power to the cargo spacecraft, mainly considering that the cargo spacecraft is installed at the stern of the core cabin, and the cargo spacecraft’s solar battery wings are small in size and are easily blocked by other combinations of the space station. The cargo spacecraft supplies power to the core cabin for the purpose of Responding to the very rare special situations that may occur in the future space station, this also demonstrates the flexibility and reliability of the power supply of the entire space station assembly." said Wang Zhenxu, chief designer of the power supply subsystem of the cargo spacecraft.

　　In order to receive the 2000 watts of power from the core cabin, the cargo spacecraft itself needs to undergo a high-voltage grid-connected adaptation process.

In response to the above problems, the developers have carried out a series of verification experiments to ensure that the normal operation requirements of the cargo spacecraft are met.

"Intelligent Management": Energy Saving and Environmental Protection

　　When the Tianzhou-2 cargo spacecraft is connected to the grid for power supply in the Tianhe core module of the China Space Station, how to deal with the excess electricity?

Developers have their own methods.

Wang Zhenxu introduced that a shunt regulator is installed in the "Tianzhou No. 2" cabin. Through the shunt regulator, the excess electricity of the solar battery wing can be shunted. The subsystem can always adapt. This is the intelligent management of the power subsystem in the'space station era'."

"Responding to a brilliant move": seven charging control methods

　　The mission of the lithium-ion battery begins 1 hour before the launch of the cargo spacecraft; after the launch, flight, and orbit, the power is provided by the lithium-ion battery before the solar panel is deployed.

During the rendezvous and docking, in order to reduce the impact of the docking impact on the solar panels, the solar panels will be placed in a horizontal return to zero state. At this time, most of the power still needs to be provided by lithium-ion batteries.

　　The unique "seven charging control methods" of the cargo spacecraft played a role.

According to Zhu Chao, the deputy director designer of the power supply subsystem of the cargo spacecraft, according to the life cycle of lithium-ion batteries, the developers have set up seven charging control methods, corresponding to normal mode, failure mode and flexible mode, "in order to adapt to the rapid docking state. ,'Tianzhou 2'adopts a different charging control method from'Tianzhou 1', increasing the capacity of the lithium-ion battery pack by about 10 ampere hours, effectively ensuring that the battery power can be used by the cargo spacecraft."

"Upgrade charging skills": Overcoming signal misunderstandings

　　Zhu Chao introduced, "Before charging the lithium-ion battery, it was necessary to collect the signal of the solar panel. However, in the "false shadow area" where the solar battery wing is blocked by a large area, this signal does not reflect the actual state of the solar panel in orbit. The battery will be overcharged or undercharged. For this reason, the team optimized and upgraded the battery charging control method."

　　Zhu Chao said that the new charging control method adds a strategy that can monitor the voltage of lithium-ion battery cells and battery packs throughout the cycle. The upgrade from version 1.0 to version 2.0 effectively solves the technical problems of lithium-ion battery charging control in the complex combination of space stations in the future, and improves the reliability and safety of the cargo spacecraft." (End)