November 4, 2024，By Graduate School of Shandong University、Sponsored by the Postgraduate Affairs Department of the Party Committee，The 63rd issue of 2024 (the 1400th issue in total) "Jixiafeng" graduate student academic forum hosted by the School of Electrical Engineering was held in the lecture hall on the fourth floor of the Electric Power Building on Qianfoshan Campus。This forum invites Professor Ralph Kennel from the Technical University of Munich in Germany and Teacher Gao Jianbo from the Laser Institute of the Shandong Academy of Sciences to give lectures，The forum is hosted by Professor Zhang Zhenbin and Associate Professor Li Zhen。
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Professor Ralph Kennel gave a wonderful report on the application of power electronics in various fields。Professor Kennel first briefly introduced the basics of power electronics，That is, realizing electrical physical quantities (voltage through power semiconductor devices，Current，Efficient conversion of power，Applied to buck-boost、Frequency conversion、Interference compensation and equipment control scenarios。Professor Kennel then focused on the current source inverter (CSI)，And pointed out that the statement in a certain literature that CSI is not as dynamic as voltage source inverter (VSI) is wrong，CSI output voltage can achieve the same dynamic control as VSI output current，But the connection between CSI and motor requires capacitive decoupling，And multiple CSIs should be connected in series on the same DC link。Professor Kennel’s example of controlling CSI experimental waveforms through PWM，Shows its control effect。
Subsequently， Professor Kennel introduced the matrix inverter，Matrix inverter realizes the conversion of one AC system into another variable frequency AC system，The maximum line voltage forms the “DC link voltage”。This inverter has good output voltage and current characteristics、Low line voltage harmonics、Advantages such as no DC link capacitors and inductors。
final，Professor Kennel discussed model predictive control (MPC) and impedance source inverter with students。MPC model-based control，Including direct model predictive control and other predictive control methods。The advantage lies in the ability to utilize system model knowledge、Consider inverter limitations and dynamic behavior、Improved nonlinear system representation、No need for complex cascade structure、Good dynamic performance；The limitation is that the processing performance is high and its steady-state accuracy and dynamic behavior depend on the accuracy of the model parameters。The impedance source inverter uses the impedance source as the DC link，At low DC link voltage，Charge the inductor and increase the voltage by turning on the power devices at the same time，Combined boost converter and frequency converter functions，Suitable for applications with low input voltage。Professor Kennel pointed out，MPC control shows better performance in quasi-Z source inverter，If the output current total harmonic distortion (THD) is lower in steady state、Faster dynamic response，This is due to the branch and bound and move blocking strategy。
After the report ends，Professor Kennel had an in-depth discussion with the students on the lecture content，Students benefited a lot。
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Subsequently，Teacher Gao Jianbo talks about servo forging technology，Bring a wonderful report to the students。
First of all, Teacher Gao Jianbo introduced the current status of servo forging technology to the students。Teacher Gao introduced the principle of mechanical press，And presses in cars、Home appliances、Wide applications in aerospace and other fields，Then compared the servo press with the traditional press，Explains the performance of servo presses、Energy consumption、Characteristics such as price，And its forging、Cold extrusion、Application in various processing techniques such as blanking。Details two existing servo drive technologies for rotation and linear motion，includes crank and screw drives，Analyzed their advantages and disadvantages，Such as crank-driven low-speed stamping、High-speed return、Features such as increased strength of the toggle lever，And the linear output of the screw drive、Larger travel and other features。Teacher Gao Jianbo also displayed related products at home and abroad，Point out the current situation that domestic servo forging equipment relies heavily on foreign electronic control systems。
Later, Mr. Gao Jianbo analyzed the development status of servo presses at home and abroad。The development trends of servo press technology at home and abroad are similar，But the domestic market acceptance needs to be improved；Small domestic batch size、Heavy price，High volume abroad、Quality first，Resulting in different market demands for servo presses。Analysis through academic literature and patent quantity，Teacher Gao Jianbo pointed out that domestic industry attention lags behind，Currently in the low period of the industry，It is predicted that the market share of domestic servo presses will increase in the future。
Finally, Teacher Gao Jianbo showed the students the results of the industrialization of new servo forging technology。Teacher Gao’s team independently developed a high-power servo driver、Direct drive motor、Servo forging control system and applied to 150-ton multi-link servo press、315 ton and 400 ton electric screw press、1000 tons electric screw press and other equipment。and，my country’s servo forging R&D team is currently responsible for the control system integration of multiple projects，Such as the 630-ton servo press of Hefei Midea Washing Machine Factory、Shanxi Dayun 6400-ton fully automatic stamping production line, etc.，Products are used in the production of new energy vehicles，Some projects are included in the country’s first (set) new technology equipment catalog。
At the end of the academic report，Participating teachers and students took photos together。This issue of "Jixiafeng" graduate academic forum ended successfully with sparks of wisdom and warm applause。
About the speaker:
Ralph Kennel，Chair Professor at Technical University of Munich, Germany，IET Fellow，Chartered Engineer，IEEE Member-at-Large, Former PELS Vice Chairman。Mainly engaged in encoderless control of electric drive systems、Power electronic system predictive control、Research on energy transmission, etc.。Professor Kennel served as R&D Director of Robert BOSCH (Germany) from 1983 to 1999、Department Head、CTO and other positions，is the setter of multiple standards in the field of German servo and industrial electronics；Served as Chair Professor at Wuppertal University in Germany from 1999 to 2008；Served as Chair Professor at Technical University of Munich since 2008。Won the IEEE - Harry Owen Distinguished Service Award、EPE Outstanding Achievement Award, etc.。Professor Kennel is from the National University of Science and Technology、Harbin Institute of Technology、Part-time chair professor at Shandong University and other units，Actively promote Sino-German scientific and technological cooperation。
Gao Jianbo，People from Qingdao, Shandong，Researcher at the Laser Institute of Shandong Academy of Sciences。
Studied in the Automation Department of Tsinghua University in 1989，Bachelor's degree、Master’s and PhD degrees。went to Germany to work in 2001，At the Fraunhofer Institute in Germany、Technical University of Munich and enterprises engaged in scientific research and management work。Former R&D engineer、Director of China Business Department、Chief Engineer、Partners and founders of high-tech companies, etc.。Return to China in 2017，Strive to promote the research and development of independent intellectual property rights control technology for domestic forging machine tools。
Mainly engaged in high-end equipment、Motion Control、Application research and industrialization work of power electronics and related technologies。Won more than 10 invention patents as the first inventor，Published more than 30 papers。Completed multiple government-funded projects including provincial key R&D projects，Total 18 million yuan。Presided over more than 20 corporate new technology development projects，Total output value exceeds 30 million yuan。Among them, the 64000 kN fully automatic stamping production line is included in the national "First (Set) Major Technical Equipment Promotion and Application Guidance Catalog"。Scientific research achievements won the second prize of Shandong Province Science and Technology Progress Award，Achieve industrial transformation of more than 60 million yuan。The company founded was supported by the key project of the "Returning to China and Entrepreneurship Startup Support Plan" of the Ministry of Human Resources and Social Security in 2022。
