\u3000\u3000
Science and Technology Daily reporter Li Liyun correspondent Huo Ping
China’s “double carbon” strategy advocates a green, environmental friendly and low-carbon lifestyle, which depends on the continuous development and innovation of green energy technology. With the vigorous development of renewable energy in China, the recycling of micro energy in the real environment such as magnetic energy has attracted the attention of many researchers.
Chu Zhaoqiang, a young teacher and associate professor of the “marine magnetic sensor and detection” team of the school of underwater acoustic engineering and innovation and development base of Harbin Engineering University, studied and designed a new structure of weak magnetic energy collector, which can avoid all kinds of manual cumbersome operations such as replacing and repairing the battery of the Internet of things sensor, realize “self generation” under the condition of weak magnetic field, and its output power is about 120% higher than that of the traditional magnetic energy collection structure. Recently, the research academic paper “significantly enhanced weak magnetic energy recovery performance in magnetic force electric energy capture devices clamped at both ends” was published online in the international famous journal advanced energy materials in the field of energy materials.
Recycling micro energy in the environment
“Interconnection of all things” is an important engine for building an intelligent world, and it also gives birth to the rapid development of Internet of things technology. At present, a major challenge in the development of the Internet of things is to find the self powered technology of sensor communication nodes to support the construction of large-scale and distributed sensor networks.
In response to this technical challenge, many fields in China are actively planning to solve it. The national key research and development plan “smart sensor” in 2021 focuses on the problem of self energy supply and network access of human multi parameter biosensors in wireless scene, and puts forward the self energy supply technology to obtain energy from human body; The national key research and development plan “smart sensor” in 2022 focuses on the problem of energy supply and access of distributed sensors for state sensing of distribution and consumption network, and puts forward the project guide of magnetoelectric coupling self powered magnetic field sensitive elements and sensors; In 2022, the National Natural Science Foundation of China also included the research on micro piezoelectric vibration energy capture technology for aerospace into the scope of the guide.
It can be said that the development of distributed energy acquisition technology to realize the recycling and reuse of micro energy in the environment is of great value. It is also an effective measure to respond to the national energy conservation and emission reduction strategy and help reach the peak of carbon.
For the recycling of environmental micro energy, among many collectable energy sources such as vibration energy, radiation energy and near-field electromagnetic energy, the stray magnetic energy generated by power cables, industrial machinery and household appliances has been paid more attention by researchers because of its fixed frequency and wide distribution, which is more efficient than low-frequency energy such as wind energy. Especially in the context of building a smart grid, the on-line monitoring and fault diagnosis of transmission line state parameters urgently need to capture energy from overhead cables to build a sustainable self energy supply sensor network.
Just like the beautiful Shanghai New World Co.Ltd(600628) , described in the novel three bodies, the cup can be heated by itself without power supply and battery, and the flying car in the air can fly without battery, but there will never be no electricity. It is a wireless power supply field formed by the power supply using microwave or other forms of electromagnetic vibration to generate electricity. This technology is actually the technology currently used for wireless charging of mobile phones. At first, people also paid attention to this traditional coil induction power collection device. However, this technology has some prominent problems, such as large volume, inconvenient installation and difficult to withstand short-term high current impact.
Therefore, people began to study an energy capture device that converts magnetic energy into mechanical energy and then into electrical energy (MME). This technology is expected to become a new choice for the next generation of low-frequency magnetic field energy collection.
Chu Zhaoqiang introduced that this new energy capture device uses the magnetic torque effect and hysteresis expansion effect, and then uses the piezoelectric effect to realize the conversion between mechanical energy and electrical energy. Its advantage is that it does not need the closed magnetic circuit required by the coil induction power taking device, and can realize more efficient energy conversion and higher tolerance to strong current pulses.
A new method for low field energy collection
Chu Zhaoqiang has been exposed to vibration and magnetic field energy collection technology since 2016. From 2016 to 2021, he has been committed to the research of materials and devices based on traditional cantilever resonant structure. This is an energy collector structure with one end fixed and the other end free, and a mass block (magnet) is added at the free end. This structure is driven by the free end magnetic mass block, which contributes more than 90% of the equivalent mass. In this case, if the resonant frequency of the resonator at 50 Hz (Hz) is to be maintained unchanged, it is difficult to enhance the magnetic force coupling performance simply by increasing the mass of the free end magnet. For this reason, most of the cantilever magneto mechanical electrical devices studied at present are only limited to the energy collection of strong magnetic field, that is, magnetic field greater than 5 OE. The World Health Organization points out that the safety threshold of 50 / 60Hz alternating magnetic field accessible to the public is 1oe, and the stray magnetic field in the environment is generally lower than this reference value. Therefore, it is also necessary to explore new principles and methods suitable for low field energy collection.
Based on the thinking of “how to reduce the equivalent mass of the magnetic mass block at the free end of the magnetic mechanical electric energy capture device”, Chu Zhaoqiang boldly innovated and put forward a design idea of clamping beam at both ends. This design fixes both ends of the magnetic mechanical electric energy capture device, adopts a second-order vibration mode, reduces the kinetic energy of the central magnetic mass, thus reducing its contribution to the equivalent mass of the resonant system, and greatly improves the output performance of the system under the condition of 50Hz weak field while increasing the magnet volume.
Experiments show that under the same excitation conditions in the weak magnetic environment, the electric energy output of the energy collector in the same unit time is more than twice that of the traditional cantilever structure, which can make the sensor without battery work normally and communicate with the mobile phone terminal.
“In scientific research, a small or even insignificant design method often plays a key role. But the source of this method must be based on long-term research and thinking,” Chu Zhaoqiang said
Future or small Underwater Bionic platform
“At present, this energy collection technology for magnetic field has certain limitations in application. Science always solves a problem and brings many new problems.” Chu Zhaoqiang told the science and Technology Daily that in the future, he will mainly consider further optimizing the parameter design of magnetic machine electric energy capture devices clamped at both ends in terms of material and geometry, further realizing the integration of increasing the adaptive magnetic field variation range and miniaturization, and providing key technologies for the development of self powered magnetic field sensitive elements, intelligent sensing of power transmission and transformation of power grid and identification of topological relationship of power distribution network.
Chu Zhaoqiang also said that the team will combine the characteristics and advantages of ship sea scientific research of Harbin Engineering University to deeply study the wireless energy supply technology based on ultrasound and magnetic field for Small Underwater Bionic platforms such as underwater robotic fish and unmanned underwater vehicles, which can not only solve the problem of “taking” energy such as small bionic platforms, but also solve the problem of “supplying” energy.
Chu Zhaoqiang’s “marine magnetic sensor and detection” team in the school of underwater acoustics and innovation and development base of Harbin Engineering University was established and continuously developed in 2017. Aiming at the basic theory, key technologies and engineering applications of underwater target Multi-sensor Detection, the team has comprehensively carried out technical research on basic magnetic materials, magnetic sensor development, underwater information sensing and processing.
