Investigation of parallel-connected GaN E-HEMT VSI-based servo drives

2022-1-19
Yürük, Hüseyin
Nonlinearities in voltage source inverters (VSIs) are thought to be the primary cause of output voltage distortions which cause low-order harmonics in the output current. These nonlinearities also considerably degrades control performance and system stability for low-speed applications with low-inductance motors, particularly when the system operates in the low-torque area. The impact of the nonlinearities on the phase current and current control of a silicon (Si) metal-oxide-semiconductor field-effect transistor (MOSFET) based VSI are examined in this thesis using a coreless permanent magnet synchronous motor (PMSM). To address this issue, a gallium nitride (GaN) enhancement-mode high electron mobility transistor (E-HEMT) based VSI is proposed. Based on the results, a GaN E-HEMT VSI-based servo drive is being developed to replace its Si MOSFET VSI-based counterpart. It is about half the size of the previous one, allowing for the use of two servo drives in parallel rather than one for redundancy. The use of parallel-connected servo drives offers the benefit of increased torque capacity, reliability, redundancy, and modularity. Smaller variances in the system clocks of the separate microcontrollers, asynchronous pulse width modulation (PWM) carrier signals, and hardware differences, on the other hand, might cause non-identical output voltages of the parallel modules, resulting in circulating currents. These circulating currents limit parallel operation, increase power consumption, induce imbalanced power distribution, and degrade control performance. A fault‐tolerant parallel‐connected GaN E-HEMT VSI based servo drive scheme is proposed to reduce the circulating currents and to eliminate the need for extra inductors at the output and separate DC supplies at the input of the inverters. Various experimental tests are conducted with up to six parallel-connected servo drives and a PMSM for validation.

Suggestions

Comparison of the Effects of Nonlinearities for Si MOSFET and GaN E-HEMT Based VSIs
Yuruk, Huseyin; Keysan, Ozan; Ulutas, Baris (2021-07-01)
Nonlinearities in voltage source inverters (VSIs) such as; dead time, switching time, delay time, voltage drops on the power switches, parasitic capacitance, etc., are considered to be the main sources of the output voltage distortions. These distortions result in low-order harmonics in the output current, which in turn increase core losses and create torque ripples. In particular, for low-speed applications with low-inductance motors, the control performance and the stability of the system degrades substan...
Investigation of subsynchronous resonance risk in the 380 kv Turkish electric network
Ozay, N.; Güven, Ali Nezih (null; 1988-12-01)
Subsynchronous resonance (SSR) occurs when a resonant frequency of a series compensated transmission system interacts with a natural frequency of the turbine prime mover. This form of SSR is referred to as torsional interaction which, under certain conditions, may become self-excited and cause serious damage to electrical equipment and turbine shafts. The presence of a thermal power plant (Kangal) in the close vicinity of a group of series capacitors in Eastern Turkey necessitated a careful investigation of...
Analysis and Characterization of DC Bus Ripple Current of Two-Level Inverters Using The Equivalent Centered Harmonic Approach
Ayhan, Ufuk; Hava, Ahmet Masum (2011-09-22)
The dc bus PWM ripple current of three-phase two-level voltage source inverters is a function of the PWM method, the load current magnitude, power factor angle, and the modulation index. Thus, the ripple current characteristics are highly involved and difficult to understand. Using the double Fourier integral approach, this paper investigates the ripple current characteristics thoroughly for a wide range of operating conditions and PWM methods. Then, the equivalent harmonic approach is used to lump the ripp...
Implementation issues of real time position estimation for induction motors using rotor slot harmonics
Ertan, Hulusi Bülent; Keysan, Ozan (2013-11-15)
In this paper, an approach to identify rotor slot harmonics, from motor currents or from induced voltage in an internal or external search coil voltage is described. The importance of this method is that instantaneous value of the rotor slot harmonics can be determined in real time. In this manner, it is possible to determine motor speed or rotor position of a motor in a short enough time, for use in vector control. This method is independent of motor parameters. Using this method an additional feedback bec...
Modeling and Simulation of a Boost DC/AC Inverter fed Induction Motor Drive
SÜRGEVİL, TOLGA (2011-09-10)
Single-stage three-phase boost dc/ac inverters can provide sinusoidal ac output voltages which arc greater than input dc voltage without needing an intermediate dc voltage boost stage. Such a topology is cost-effective due to reduced switch count and it is suitable for compact design These unique features of this type of inverter makes it a suitable choice in many applications such as uninterruptible power supplies, variable speed ac drives, and some distributed power generation schemes. This paper aims to ...
Citation Formats
H. Yürük, “Investigation of parallel-connected GaN E-HEMT VSI-based servo drives,” Ph.D. - Doctoral Program, Middle East Technical University, 2022.