Wireless charging method for maglev train 600km/h

Scientists have developed a method of wirelessly supplying power to a maglev train while it is hovering, achieving unprecedented efficiency during a test run.

The energy efficiency of a typical wireless charger for a smartphone is around 50%. When charging an electric vehicle running with a roadside generator, almost 80% of the energy is lost, according to recent experiments. But a maglev train in the city of Qingdao in eastern China's Shandong province, designed to travel at a maximum speed of 600km/h while suspended by magnetic force, can collect electricity from the transmission coil in the road. rails with 92.4% efficiency.

A maglev train with a speed of more than 600 km/h is running in Qingdao.

Experimental results show that wireless power transmission technology based on research by scientists and engineers around the world over the past few decades is now possible for rail traffic, according to the project leader, Wu Donghua at CRRC Qingdao Sifang. Wu and colleagues published the study in the journal Southwest Jiaotong University.

Power supply is a major technical challenge in high-speed maglev technology. Although the ship is propelled forward by magnetic force, most of the equipment on board requires electricity. The battery pack used as the power source seemed too large and heavy, and the lines could not withstand the heat and abrasion at high speeds.

Linear motors, the traditional wireless power supply method used on maglev trains in Japan and Germany, can produce electricity at high speeds by collecting energy directly from the magnetic force. However, electrical disturbances occurring in the narrow distance between the train and the track can cause the transmission efficiency to decrease by more than 50%. When the train stops at the station, the linear motor cannot generate electricity.

The wireless power transmission system developed by Wu's research team works like an induction cooker. Their system is designed to convert direct current into a magnetic field with copper coils mounted on the side of the rail. When the train runs through the charged coil. An antenna on the bottom of the ship glides through the magnetic field and generates electricity during induction.

Turning the idea into reality is not easy because the additional magnetic field can be influenced by the magnetic force pushing the ship forward. A large amount of magnetic force is also lost to the medium, reducing the efficiency of electricity transmission. To overcome these obstacles, Wu and his colleagues focused on smaller details that are often overlooked, such as the shape of the receiving antenna, and developed a design like never before.

The new technology can deliver more than 170 kW of electricity to the train at all speeds, exceeding the demand from the electronic hardware on the single-carriage prototype. The difficulty in charging a train running at 600 km/h lies in supplying power to the coil, which requires at least a second. The coil that Wu and his team developed is more than 20 meters long and the ship can pass through in the blink of an eye.

The team says the technology they propose requires an extremely powerful and precise control system to turn the coils on just before the train arrives and turn off after the train passes. Otherwise, the power transmission efficiency will be greatly reduced. Due to the distance between the coils, the vessel also needs a good power management system to ensure a constant and stable power supply.