Analysis of Rotor Position Detection Performance According to the Frequency of Square Waveform Voltage in the Harmonic Injection Sensorless Method through HILS

In this paper, the rotor position estimation performance of the sensorless scheme for permanent magnet synchronous motors (PMSMs) implemented through the injection of high-frequency square-wave voltage according to the frequency of the square-wave voltage is presented through HILS (Hardware In the Loop Simulation) experiments. An inverter using an IGBT device usually has a switching frequency of around 15 kHz. On the other hand, GaN devices that can be switched on and off at frequencies higher than 100 kHz have been recently developed, and research is being actively conducted to apply GaNs to a variable speed system. The purpose of this study is to conduct HILS experiments to analysis the rotor position estimation ability of the sensorless technique in cases where a high switching frequency was applied, such as GaN devices, with that of a system having a usual switching frequency, such as IGBT. In the HILS system used in this study, an inverter and motor model implemented with Simulink are located in a real-time simulator. A sensorless motor control method was implemented with an FPGA control board, which includes a PWM interrupt service routine of 100 kHz frequency and a harmonic injection and position detection algorithm. The HILS experiments show rotor position detection errors according to the various frequency of the harmonic voltage injected for estimating the rotor position with a PWM frequency of 100 kHz cases. According to the experimental results, good position estimation was possible not only when the harmonic of 10 kHz corresponding to 1/10 of the PWM frequency was injected, but also when the harmonic of 1 kHz corresponding to 1/100 of the PWM frequency was injected. The experiments suggest that position estimation errors decrease as the frequency of the harmonic voltage increases, and, based on the foregoing, it is thought that the application of a GaN device capable of realizing a high switching frequency in a variable speed drive system can be another advantage.

Analysing Efficiency and Reliability of High Speed Drive Inverters using Wide Band Gap Power Devices

Within the project ‘ARIEL’ an electrical turbo compressor unit for fuel cell applications is deeply investigated. The necessary drive inverter is especially designed for high fundamental frequency and high switching frequency to cope with the requirements of the implemented electrical machine. This paper presents investigations on the inverter’s efficiency and its prospective lifetime at different stages of the development. In the design process different wide band gap power semiconductor devices in discrete packages are evaluated in terms of the achievable power density and efficiency, both by simulations and measurements. Finally, an optimised design using surface mount silicon carbide MOSFETs is developed. Compared to a former inverter design using silicon devices in a three-level topology, the power density of the inverter is significantly increased. The lifetime of power electronic systems is often limited by the lifetime of the power semiconductor devices. Based on loss calculations and the resulting temperature swing of the virtual junction the lifetime of the inverter is estimated for the most frequent operating points and for different mission profiles.

Unjuk Kerja GPIO, PWM, ADC dan Timer pada Mikrokontroler STM32F103, ESP32S dan ATMega328

Perangkat embedded system pada masa sekarang memiliki banyak pilihan terhadap jenis mikrokontroler yang sesuai dengan kebutuhan. Hal ini menjadi tantangan tersendiri bagi pengguna ketika diharuskan untuk memilih salah satu jenis mikrokontroler tersebut. Sebagai contoh permasalahan apakah mikrokontroler yang telah dipilih tersebut memiliki sejumlah pin GPIO yang diinginkan, dengan frekuensi switching yang tinggi, berapakah jumlah kanal, resolusi, linieritas dan durasi konversi ADC, bagaimana kemampuan peripheral internal DAC, Timer dan PWM yang bisa dibangkitkan dari mikrokontroler tersebut. Penelitian ini telah membandingkan setidaknya 4 peripheral internal utama yang dimiliki oleh 3 jenis mikrokontroler. Metode yang dilakukan adalah dengan menguji karakteristik GPIO, PWM, TIMER dan ADC pada 3 jenis mikrokontroler yaitu Arduino ATMega328, STM32F103C8 dan ESP32. Eksperiment dilakukan dengan mengevaluasi frekuensi switching digital ouput, mengevaluasi resolusi sinyal hasil konversi ADC, mengevaluasi ketepatan hasil instruksi delay berkaitan dengan timer program dan waktu konversi sinyal DAC semuanya dilakukan pada masing-masing mikrokontroler. Hasil akhir dari penelitian ini menunjukkan, mikrokontroler ESP32 memiliki unjuk kerja GPIO, PWM, TIMER dan ADC terbaik apabila dibandingkan dengan jenis lainnya. Penelitian ini juga membuktikan integrasi FreeRTOS pada Framework Arduino bisa berfungsi dengan optimal meskipun mikrokontroler berjalan pada 2 task yang berbeda di 2 core CPU yang bekerja secara pararel. Frekuensi switching digital output pada ESP32 mampu mencapai 3MHz, waktu konversi ADC hanya 5,7us dan DAC hanya 3,7us. Today's embedded systems have many choices for the type of microcontroller that suits the needs. This is a challenge in itself for users when required to choose one type of microcontroller. For example, the problem of whether the selected microcontroller has the desired number of GPIO pins, with a high switching frequency, what is the number of channels, resolution, linearity, and duration of the ADC conversion, what is the ability of the internal DAC, Timer and PWM peripherals that can be generated from the microcontroller. This study has compared at least 4 main internal peripherals owned by 3 types of microcontrollers. The method used is to test the characteristics of the GPIO, PWM, TIMER, and ADC on 3 types of microcontrollers, namely Arduino ATMega328, STM32F103C8, and ESP32. The experiment was carried out by evaluating the digital output switching frequency, evaluating the signal resolution of the ADC conversion result, evaluating the accuracy of the delay instruction results related to the program timer and DAC signal conversion time, all of which were carried out on each microcontroller. The final results of this study indicate that the ESP32 microcontroller has the best GPIO, PWM, TIMER, and ADC performance when compared to other types. This research also proves that the FreeRTOS integration on the Arduino Framework can function optimally even though the microcontroller runs on 2 different tasks on 2 CPU cores that work in parallel. The digital output switching frequency on the ESP32 is capable of reaching 3MHz, the ADC conversion time is only 5.7us and the DAC is the only 3.7us.

Improved Super Twisting Based High Order Direct Power Sliding Mode Control of a Connected DFIG Variable Speed Wind Turbine

This work presents the theoretical and practical comparison of linear and nonlinear control laws for the direct power control of a grid-connected double fed induction generator (DFIG), based wind energy conversion system (WECS) under different operating modes. We will show the improvement brought by the super twisting based high order sliding mode control to mitigate the chattering phenomenon, due to the high switching frequency. It will also avoid the hyperlink of the controller settings to the system’s mathematical model and will reduce the sensibility to external disturbances. The overall structure of the proposed control requires the use of the DFIG simplified model with field-oriented control (FOC). This last allows an instantaneous decoupled control of the DFIG stator active and reactive power by acting on dq rotor currents (Iqr , Idr ) respectively. In the preliminary tests, a comparative study is conducted to verify the superior performance of the proposed WECS control scheme during various operating modes including the maximum power point tracking MPPT mode. The study reveals the effectiveness of each implemented control law with its advantages and drawbacks.

Nonlinear Dynamics and Performance Analysis of a Buck Converter with Hysteresis Control

This paper presents the mathematical modeling and experimental implementation of a Buck converter with hysteresis control. The system is described using a state-space model. Theoretical and simulation studies show that the zero hysteresis control leads to an equilibrium point with the implication of an infinite commutation frequency, while the use of a constant hysteresis band induces a limit cycle with a finite switching frequency. There exists a tradeoff between voltage output ripple and transistor switching frequency. An experimental prototype for the Buck power converter is built, and theoretical results are verified experimentally. In general terms, the Buck converter with the hysteresis control shows a robust control with respect to load variations, with undesired high switching frequency taking place for a very narrow hysteresis band, which is solved by tuning the hysteresis band properly.

Low-Voltage GaN FETs in Motor Control Application; Issues and Advantages: A Review

The efficiency and power density improvement of power switching converters play a crucial role in energy conversion. In the field of motor control, this requires an increase in the converter switching frequency together with a reduction in the switching legs’ dead time. This target turns out to be complex when using pure silicon switch technologies. Gallium Nitride (GaN) devices have appeared in the switching device arena in recent years and feature much more favorable static and dynamic characteristics compared to pure silicon devices. In the field of motion control, there is a growing use of GaN devices, especially in low voltage applications. This paper provides guidelines for designers on the optimal use of GaN FETs in motor control applications, identifying the advantages and discussing the main issues. In this work, primarily an experimental evaluation of GaN FETs in a low voltage electrical drive is carried out. The experimental investigation is obtained through two different experimental boards to highlight the switching legs’ behavior in several operative conditions and different implementations. In this evaluative approach, the main GaN FETs’ technological aspects and issues are recalled and consequently linked to motion control requirements. The device’s fast switching transients combined with reduced direct resistance contribute to decreased power losses. Thus, in GaN FETs, a high switching frequency with a strong decrease in dead time is achievable. The reduced dead time impact on power loss management and improvement of output waveforms quality is analyzed and discussed in this paper. Furthermore, input filter capacitor design matters correlated with increasing switching frequency are pointed out. Finally, the voltage transients slope effect (dv/dt) is considered and correlated with low voltage motor drives requirements.