Zhendong - Personal Website

About Me

Hello, this is Zhendong Zhang. I am an firmware engineer that develop real-time control algorithm for electric machine in various applications such as servo motion system, vehicle electrification. My backgroud is about the eletromagnetic analysis of electric machine, power electronics converter control and analysis, different control loop bandwidth analysis, etc.

I received my Ph.D. degree in EE at Ohio State University.

Experience

I worked at UTRC as an research internal engineer from Feb, 2013 to Aug, 2013. My main job responsibility is to assist the magnetic bearing project for high speed chiller. I learned the physical modeling of 5-DOF magnetic bearing system. I also implemented a system identification algorithm to commission the system parameters using adaptive filter.

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I worked at Rockwell Automation from Sep, 2013 to Aug, 2022, first as senior firmware engineer, then project firmware engineer, and later as senior project firmware engineer.

I mainly involed in three major projects: 1) PF527 component drive; 2) PF755T high performance drive; and 3) Carrier high speed chiller drive.

I helped to develop the latest Rockwell drive product using MATLAB/model based design technology. I has involved in a series algorithm development.

Most important: Under the business cultural framework - "WE ARE ONE, SPEED, INNOVATION, and ACT LIKE AN OWNER". I have worked with a group of experienced, hardworking, and modest engineers. They not only taught me all the knowledges, but also serves as the engineer role model . The management team sets up an group culcture that every engineer is respected and they always try their best to service the needs of individual engineer during their work and care about their life as well.

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Navigation

Projects(Embedded Firmware Developoment)

Carrier, 580Hp, 13500Rpm, Ipm chiller

In recent years, the HVAC industry is going greener by adopting eco-friendly solutions. Variable speed drives (VFD), being the core part of the system, is supposed to run a machine to super-high-speed, with extreme-high-efficiency, and feed minimum-harmonics to the grid. Conventional VFD system with six-pulse front end structure, induction machine, and speed boost gearbox can no longer satisfy these requirements. In this project, a turbo-compressor chiller equipped with a high-speed hermetic IPM motor and Rockwell’s latest PowerFlex 755T active front end (AFE) drive technology is introduced. Position sensorless control is achieved in full speed range including compressor high dynamic conditions such as surge and power loss.

I am the control firmware lead on this project. Iam responsible to modify and iterate the firmware to drive a high speed IPM motor. Successfully win the large order from one of the biggest HVAC customer. Design sensorless algorithm using High Frequency Injection(HFI) at low speed and synchronous frame back-EMF at high speed to demonstrate stable operation across various points on compressor map including compressor surge points

PowerFlex 755TL, TR, and TM Drives

Rockwell Automation Next Generation High performance controller (755T series) development. The new drive series has three major offering, the 755TM for common bus application, the 755TL for low harmonic application, and the 755TR for energy regeneration. For the drive firmware, it adopts the latest model based design technology based on MATLAB/SIMULINK platform. My daily tasks are model design review, model code review, model unit test, report generation, as well as model validation on the dyno.
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PowerFlex 527 Cip Motion Drive

PowerFlex 527 is the component class drive with CIP motion only capability on Rockwell drive portfolio. Read more »

Software Development Tools & Process

Project Management: Scale Agile Framework(SAFe), Lean Development Process

Sprint Planning, Sprint Review, Retrospective Review, Agile Release Train

Software Development Cycle

Design Review, Design Guideline, Code Review, Naming Convention, Unit Simulation Test(Test Case, Test Harness), Report Generation, Bench Test Validation

DevOps Process

Python Build Machine, Build in Command Window, Git Repository, Teamcity CI/CD, JFrog Artifactory, Build Promotion Level, Smoke Test

Matlab Model Based Design

High Level Design Document, Modularized architecture(shared modules vs project specific module), MAAB, MISRA-C, Coverage Report, Dead Logic Check

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Publications more »

(pdf)
Zhendong Zhang. Sensorless Back EMF Based Control of Synchronous PM and Reluctance Motor Drives—A Review. IEEE Trans. Power Electron., vol. 37, no. 9, pp. 10290–10305, Sep. 2022.
abstract▾ | bib▾

This paper reviews the state-of-the-art back-EMF based sensorless schemes for synchronous machines. Field oriented control (FOC) of a synchronous machine requires real time rotor position for decoupled torque and flux control. Extraction of rotor position without sensor or sensorless control has been an enabling technology for the past few decades. Sensorless control using back-EMF voltage induced by rotor movement is the most widely used method. However, the connections and differences between different methods has not been thoroughly investigated and documented. This paper first reviews basic sensorless methods. The two implementation forms of observer are examined to facilitate analysis. A detailed analysis puts in evidence the connections behind different methods in both stationary and synchronous reference frames. A summary is drawn that is meant to offer few key points regarding different sensorless methods. Finally, a conclusion is given to summarize the major contributions of this paper.
```
@inproceedings{Zhendong Zhang_2022_PELS
                                            title={Sensorless Back EMF Based Control of Synchronous PM and Reluctance Motor Drives—A Review},
                                            author={Zhendong Zhang},
                                            booktitle={IEEE Trans. Power Electron., vol. 37, no. 9},
                                            editor = {Z. Ghahramani and M. Welling and C. Cortes and N.D. Lawrence and K.Q. Weinberger},
                                            publisher = {IEEE.},
                                            pages = {10290--10305},
                                            year={2022}
                                            }
                                        
```
(pdf)
Zhendong Zhang, David Leggate, Takayoshi Matsuo. Industrial inverter current sensing with three shunt resistors: Limitations and solutions. IEEE Trans. Power Electron., vol. 32, no. 6, pp. 4577–4586, Jun. 2017.
abstract▾ | bib▾

This paper reviews the state-of-the-art back-EMF based sensorless schemes for synchronous machines. Field oriented control (FOC) of a synchronous machine requires real time rotor position for decoupled torque and flux control. Extraction of rotor position without sensor or sensorless control has been an enabling technology for the past few decades. Sensorless control using back-EMF voltage induced by rotor movement is the most widely used method. However, the connections and differences between different methods has not been thoroughly investigated and documented. This paper first reviews basic sensorless methods. The two implementation forms of observer are examined to facilitate analysis. A detailed analysis puts in evidence the connections behind different methods in both stationary and synchronous reference frames. A summary is drawn that is meant to offer few key points regarding different sensorless methods. Finally, a conclusion is given to summarize the major contributions of this paper.
```
@inproceedings{Zhendong Zhang_2022_PELS
                                            title={Industrial inverter current sensing with three shunt resistors: Limitations and solutions},
                                            author={Zhendong Zhang, Dave Leggate, Takayoshi Matsuo},
                                            booktitle={IEEE Trans. Power Electron., vol. 37, no. 9},
                                            editor = {Z. Ghahramani and M. Welling and C. Cortes and N.D. Lawrence and K.Q. Weinberger},
                                            publisher = {IEEE.},
                                            pages = {10290--10305},
                                            year={2022}
                                            }
                                        
```
(pdf)
Zhendong Zhang, Longya Xu Dead-Time Compensation of Inverters Considering Snubber and Parasitic Capacitance. IEEE Trans. Power Electron., vol. 29, no. 6, pp. 3179-3187, 2014.
abstract▾ | bib▾

In power electronics drive systems, dead time is used to prevent shoot-through over power devices. However, dead time can lead to distortion of ac output voltages and currents. Various compensationmethods have been proposed to overcome this drawback. However, most strategies assume the power switches as ideal switches and the transition from ON to OFF or vice versa is infinitely fast. In this paper, effects of inverter snubber and parasitic capacitance to the switching instants are investigated when doing dead-time compensation. A new dead-time compensation method is presented with the capacitance being considered. It is verified that the compensation becomesmore accurate and effective for the specific application after the modification. It is also shown that the proposed compensation can make the inverter system stable and robust. This proposed approach is validated by the experimental results.
```
@inproceedings{Zhendong Zhang_2022_PELS
                                            title={Industrial inverter current sensing with three shunt resistors: Limitations and solutions},
                                            author={Zhendong Zhang, Dave Leggate, Takayoshi Matsuo},
                                            booktitle={IEEE Trans. Power Electron., vol. 37, no. 9},
                                            editor = {Z. Ghahramani and M. Welling and C. Cortes and N.D. Lawrence and K.Q. Weinberger},
                                            publisher = {IEEE.},
                                            pages = {10290--10305},
                                            year={2022}
                                            }
                                        
```
(pdf)
Zhendong Zhang, Jacob Lamb. Active Q Flux Concept for Sensorless Control of Synchronous Reluctance Machines. IEEE Trans. Ind. Electron., vol. 70, no. 5, pp. 4526-4536, May. 2023.
abstract▾ | bib▾

In this article, we propose a new scheme to use active flux on the q-axis for sensorless control of synchronous reluctance machines (SynRMs). Conventionally, “active flux” on the d-axis is adopted to convert a salient-pole machine into a fictitious nonsalient-pole machine. However, the injected d-axis flux can deteriorate high-frequency injection (HFI) sensorless control performance or even run the system into unstable region at low speed. This article demonstrates that active flux on the q-axis can support back EMF sensorless control at high speed and improve low-speed HFI performance substantially. A seamless transition from HFI sensorless method to back EMF voltage method is attained after adopting the proposed active q flux. The experimental results are used to validate the proposed method.
```
@inproceedings{Zhendong Zhang_2022_PELS
                                            title={Industrial inverter current sensing with three shunt resistors: Limitations and solutions},
                                            author={Zhendong Zhang, Dave Leggate, Takayoshi Matsuo},
                                            booktitle={IEEE Trans. Power Electron., vol. 37, no. 9},
                                            editor = {Z. Ghahramani and M. Welling and C. Cortes and N.D. Lawrence and K.Q. Weinberger},
                                            publisher = {IEEE.},
                                            pages = {10290--10305},
                                            year={2022}
                                            }
                                        
```

Recognition

Demo Inverter at Carrier Facility — Rockwell Automation Innovation Award 2022

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