The “2019 Shanghai Science and Technology Awards Ceremony” was held on the morning of May 19 in the Central Hall of the Shanghai Exhibition Center, solemnly recognizing science and technology workers who have made outstanding contributions to Shanghai’s innovation-driven development and socio-economic progress.

According to the “Shanghai Municipal Regulations on Science and Technology Awards,” after review by the Municipal Science and Technology Award Review Committee, approval by the Municipal Science and Technology Award Committee, and endorsement by the Shanghai Municipal People’s Government, 308 awards (individuals) were presented in the 2019 Shanghai Municipal Science and Technology Awards.

The award categories include the Science and Technology Meritorious Service Award, the Young Scientists Outstanding Contribution Award, the Natural Science Award, the Technical Invention Award, the Scientific and Technological Progress Award, the Science and Technology Popularization Award, and the International Science and Technology Cooperation Award, among others. The “Key Technology Development and Application of Intelligent and Safe Elevator Drives” project by STEP has been awarded the “Shanghai Science and Technology Progress Award.”

Shanghai Science and Technology Progress Award
·Project Name: Development and Application of Key Technologies for Intelligent and Safe Elevator Drives;
·Project Participants: Jin Xinhai, Chen Wei, Wang Gaolin, Li Wujun, Li Baisong, Li Xinghe, Xu Dianguo
·Primary completing unit:
Shanghai Xinglinna STEP Motor Co., Ltd.
Shanghai STEP Electric Co., Ltd.
Harbin Institute of Technology

This project falls within the fields of advanced manufacturing and fundamental core components. The elevator drive is the “brain” of elevator equipment. The intelligent, safety-oriented elevator drive developed under this project can ensure the safe, comfortable, and energy-efficient operation of elevators. It represents a new-generation elevator drive product and features the following six major innovations:

1) Current Predictive Control Technology. An improved current predictive control technique is proposed, which addresses the issue that conventional PI control is significantly affected by motor parameters. This technique markedly increases the bandwidth of the current loop and accelerates the system’s response speed, thereby achieving superior control performance. Meanwhile, a method for eliminating steady-state current error is introduced, enabling the removal of steady-state current errors caused by parameter mismatches between the controller’s motor model and the actual motor.

2) Direct-drive elevator startup anti-slip control technology. At the moment of elevator startup, the traction machine suddenly experiences a force. To ensure smooth elevator startup, the speed must be continuously maintained at zero. This project adopts a zero-static-error speed predictive control approach. Building upon the conventional finite-set model predictive control, it introduces a disturbance estimation module specifically designed to address the strong disturbances occurring during elevator startup. By correcting the model deviations caused by these strong disturbances, this method not only maintains torque output that balances out the disturbances but also eliminates the steady-state speed error under zero-servo conditions, thereby ensuring that the elevator remains stable and does not slip during steady-state operation.

3) Maximum Torque per Ampere (MTPA) Control Technology for Permanent Magnet Synchronous Motors. A novel online MTPA control strategy is proposed, based on self-correction of the current vector angle. By continuously adjusting the current vector angle using sampled stator current values and incorporating a fast Fourier transform (FFT) module, the magnitudes of the current vectors under different vector angles are compared in real time. This allows the system to identify the optimal current vector angle that corresponds to the minimum current magnitude, thereby achieving the maximum torque per ampere ratio, reducing motor losses, and minimizing switching losses in the inverter devices.

4) Parameter Identification Technology for Motors in a Standstill State. This research focuses on methods for identifying motor parameters under stationary conditions for AC motors. Specifically, for voltage-source inverters, an adaptive compensation method is proposed to address the nonlinearity of power devices. This compensation method does not require knowledge of the switching characteristics of power devices and does not necessitate compensation for dead-time effects, making it highly robust. After applying this method to compensate for voltage variations, the identified parameter values exhibit high accuracy.

5) Functional safety technology. In the elevator industry, safety is of paramount importance. Developing variable-frequency drives equipped with a Safe Torque Off (STO) function can eliminate the need for output contactors and reduce electromagnetic noise. The STO function cuts off the control voltage to the power semiconductors, preventing the inverter from generating the voltage required to rotate the motor. When the STO function is activated, the inverter’s power supply is safely disconnected. As a result, the inverter cannot produce torque, thereby eliminating the risk of hazardous movements.

6) Fault diagnosis technology. We propose an automatic detection method for the holding brake torque and an encoder fault diagnosis method. The automatic detection method for the holding brake torque can accurately determine whether the holding brake’s braking torque meets the specifications and predict the remaining service life of the holding brake device, thereby alerting maintenance personnel to perform replacements in a timely manner. This enhances elevator operational safety and simplifies elevator maintenance procedures. The encoder fault diagnosis method can identify encoder malfunctions, thus preventing safety issues caused by encoder failures.

During the implementation of this project, 10 authorized invention patents were obtained, and 20 papers were published in core journals both domestically and internationally, all of which have been indexed by SCI and EI. The project also led the formulation of one national standard and participated in the development of two other national standards. According to a technology novelty search conducted by the Chinese Academy of Sciences, this project demonstrates creativity and novelty in both its underlying principles and design, and its overall technological capabilities have reached an internationally advanced level.

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