Recently, the High-Tech Department of the Ministry of Science and Technology organized, via video conference, the acceptance meeting for the “12th Five-Year Plan” National Science and Technology Support Program project titled “Research and Application Demonstration of Key Technologies for High-Power Electro-Hydraulic Components and Precision Transmission Basic Parts.” The on-site acceptance was successfully passed.
 
Shanghai STEP Electric Co., Ltd. has undertaken a sub-project under this program, titled “Development and Application of Key Technologies for High-Power Frequency Converters Dedicated to Port Cranes.” The participating institutions in this project include: Shanghai Zhenhua Heavy Industry (Group) Co., Ltd., Harbin Institute of Technology, and Tongji University.
 
This project focuses on developing a series of frequency converters specifically designed for lifting applications. It aims to implement key technologies—including weak magnetic field control, anti-sway control, deviation correction control, synchronous control, and open-loop vector high-torque control—on container cranes (including quay cranes, rubber-tired gantry cranes, rail-mounted gantry cranes, and portal cranes) and grab卸船 machines. Furthermore, the aforementioned technologies will be commercialized and widely promoted for practical application.

Hong Kong Aircraft Inverter | Application Site in Shanghai Waigaoqiao

Major scientific and technological achievements obtained

1) Achievements in high-power variable-frequency drive products
AS700 Series Industrial Variable Frequency Drives
AS600 Series Frequency Converters for Lifting Applications
AS510 Series AFE Rectifier Unit
AS520 Series Inverter Drive Unit for Lifting Applications
EBU series braking units and intelligent holding brakes
30-500kW full-range four-quadrant load testing platform.

    
2) Achievements in key technology research
High-speed weak-magnetic-field control employs an optimized control method for torque and excitation currents based on voltage closed-loop regulation. In terms of zero-speed high-torque control technology, a rotor position estimation method based on high-frequency signal injection is adopted. Regarding asynchronous motor operation at zero frequency, an innovative zero-frequency operation approach based on voltage compensation is proposed. For inverter fault diagnosis and fault-tolerant control, a comprehensive set of fault-diagnosis and fault-tolerant control methods is presented, covering issues such as switching-device failures, current-sensor failures, and speed-sensor failures. To suppress shaft voltage and shaft current in motors, active feedforward filters and PWM-feedback active filters are utilized. For anti-rolling and correction purposes, a GPS- and Beidou-based position-correction control technology is proposed. In the area of active front-end rectification technology, a phase-locked loop based on the sliding Goertzel transform is applied, and a repetitive control method using an LCL filter in the two-phase stationary reference frame, along with a current decoupling control strategy under inductor imbalance conditions, are proposed. As for intelligent brakes, both electro-hydraulic and electromagnetic intelligent brakes have been developed, and their mechanical performance has been tested. A smooth-braking strategy has been applied to emergency-stop braking scenarios, enabling smoothly decelerated stopping of high-speed mechanisms; furthermore, the feasibility of the intelligent brakes has been verified through experimental testing.

3) Achievements in production lines and application demonstrations
The research team also provided experimental prototypes and production prototypes, as well as related process studies and technical solutions for implementing the variable-frequency drive technology requirements for port machinery. During the industrial-scale field implementation of this project, the following key equipment was developed: ① A multi-motor synchronous control test bench, which is used to study new methods for synchronously testing multiple motors in quay cranes; ② A new intelligent rubber-tired gantry crane prototype—a product resulting from the integrated application of multiple technologies, featuring a lightweight RTG design, an eight-rope anti-sway system, container handling capabilities, a differential gearbox combined with a Rebar drum, and intelligent electric trolley lifting and slewing mechanisms, along with automated operation features; ③ A 60T electrically controlled test bench for quay cranes, primarily used to evaluate the performance indicators of STEP variable-frequency drives; ④ A new automated terminal rail-mounted gantry crane prototype for container handling. During the project’s implementation, two high-power unit manufacturing assembly lines with a capacity of 500 sets each were established, capable of simultaneously supporting on-site assembly work for up to 10 large-scale port machinery electrical control systems. Additionally, four load testing benches with capacities ranging from 200 kW to 1,500 kW were built, along with one set of aging test equipment designed specifically for PCB board aging tests of variable-frequency drives.

Patents, software copyrights, etc. become

Through the implementation of this project, we have mastered the core technologies of low-voltage high-power frequency converters; we have also proposed a systematic specification for domestically produced low-voltage high-power frequency converters. During the project period, we filed 30 invention patent applications, 11 of which have been granted; published 17 papers; and obtained 2 software copyrights. In addition, we participated in the drafting of one industry standard related to frequency converters specifically designed for lifting applications. Both theoretically and practically, this project has laid a solid theoretical foundation and provided strong intellectual support for its smooth advancement.

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No. 1560, Siyi Road, Jiading District, Shanghai Municipality