Altı-adımlı asenkron motor sürücüsü ile orta gerilim seviyesinde rezonans aşırı gerilimlerinin analizi

In this thesis, it has been focused on power systems with a six-step 120-degree induction motor drive in medium voltage level. These systems may be preferred instead of PWM based systems in facilities such as geothermal power plants and submarine oil wells where all operations must be maintained with high safety standards, since dead-time control of them is easier. However, due to the harmonics generated by the switching elements they contain and the resonance and overvoltage problems they bring, they can cause hazards that may result in the burnout of the elements. The magnitude of this hazard can further enhance with the effects of the element such as long cables and motors. In these fields, it is important to determine the resonance frequency and prevent it to coincide with any harmonic frequency before the destructive effects are seen, since the maintenance of the elements may be difficult due to the depth or distance at which the element is located. In this thesis, analytical methods and computer simulations are used to determine the resonance frequency. Also, factors that may affect resonance conditions were examined and recommendations were made to reduce the effects of resonance.