Patryk Strankowski

Variable Speed AC Drives with Inverter Output Filters: Guzinski/Variable Speed AC Drives with Inverter Output Filters

The advance of variable speed drives systems (VSDs) engineering highlights the need of specific technical guidance provision by electrical machines and drives manufacturers, so that such applications can be properly designed to present advantages in terms of both energy efficiency and expenditure. This book presents problems and solutions related to inverter-fed electrical motors. Practically orientated, the book describes the reasons, theory and analysis of those problems. Various solutions for individual problems are presented together with the complete design process, modelling and simulation examples with MATLAB/Simulink on the companion website. A key focus of Variable Speed AC Drives with Inverter Output Filters is to examine the state variables estimation and motor control structures which have to be modified according to the used solution (filter). In most control systems the structure and parameters are taken into account to make it possible for precise control of the motor. This methodology is able to include modifications and extensions depending on specific control and estimation structures.

Sensorless control of five-phase induction machine supplied by the VSI with output filter

In this paper, a novel sensorless control structure based on multi-scalar variables is proposed. The static feedback control law is obtained by using the multi-scalar variables transformation, where the multi-scalar variables approach allows a full linearization of the nonlinear system. The control system could be described as “optimized” because of the minimized number of controllers. Furthermore, control system is divided into two independent control systems which are synchronized by additional controllers. The first control system is responsible for the generation of the 1st fundamental harmonic, while the second control system is responsible for the generation of the 3rd harmonic. Both control systems are synchronized and ensure a trapezoidal shape of air gap induction waveform regardless of the machine operation point. In order to ensure a sensorless control system the rotor angular speed and the state variables are estimated by a speed observer. This speed observer is based on the backstepping approach. All analytical proposed assumptions are confirmed by simulations and experimental results.

Five-phase induction motor drive with sine-wave filter

The paper presents closed-loop ac drive with 5-phase induction motor operating with voltage source inverter and sine-wave filter. The motor supply voltages and currents have sinusoidal shape. For well known adjustable electric drives the field oriented control method with flux and speed control can be applied. In the presence of output filter both control and estimation algorithms should be modified due to sine-wave filter installation. The major advantage of the drive with speed observer is an operation without motor speed sensor based on inverter currents and voltage embedded sensors. In this paper sensorless operation of a five-phase induction motor drive with inverter output filter is accomplished. The validation of the drive operation was proved by simulation and experiments. The test bench was developed with prototype of 5-phase 4.3 kW induction motor and inverter with DSP control and sine-wave filter is designed and built.

Sensorless field oriented control of five phase induction motor with third harmonic injection

In this paper, a sensorless field oriented control system of five-phase induction machine with the 3^rd harmonic rotor flux is presented. Two vector models, α<inf>1</inf>-β<inf>1</inf> and α<inf>3</inf>-β<inf>3</inf>, were transformed into d<inf>1</inf>-q<inf>1</inf>, d<inf>3</inf>-q<inf>3</inf> models oriented in rotating frames, which correspond to the 1^st and 3^rd harmonic plane respectively. The authors proposed the linearization of the model in d-q coordinate frames by introducing a new variable “x” which is proportional to the electromagnetic torque. Based on the static feedback control law, a dual mathematical model of the five-phase induction machine was linearized to synthesize a control structure in which electromagnetic torque and the rotor flux in each plane can be independently controlled. The control system proposed includes two uninfluenced subsystems (related to the 1^st and 3^rd harmonic), which are specifically synchronized to obtain a quasi-trapezoidal air gap flux distribution. This pattern provides a better iron utilization without saturating it, which consequently, increases the output torque. To accomplish a sensorless control configuration the state machines variables and the rotor speed are estimated by an extended speed observer. The proposed control algorithm was verified on an experimental setup. The results presents the desired air gap flux in steady as well transient states under various load conditions.

Sensorless fault detection of induction motor with inverter output filter

The paper presents the problem of monitoring and fault detection of a sensorless voltage inverter fed squirrel cage induction motor with LC filter. The detection is based on load torque estimation of the investigated torque transmission system. The load torque is calculated besides the computation of other variables that are mandatory for sensorless drive operation such as rotor flux and speed. The implemented LC filter smooths the voltage inverter output voltage to a close sinusoidal shape and improves the efficiency and faultless operation time of the motor. Nevertheless, this additional elements have to be considered in the control structure whereby the control will become more complicated. The properties of an observer system will be compared with focus on disturbance detection in a torque transmission system. The tests are done on a drive system which consists of two coupled 5.5 kW squirrel cage induction motors, where one machine serves as disturbance generator of different amplitudes and frequencies. The second machine represents the investigated object with LC filter and is equipped with a disturbance detection procedure. The paper includes theoretical background as well as the experimental results of the proposed solution.

Sensorless disturbance detection for five phase induction motor with third harmonic injection

The paper presents a sensorless disturbance detection procedure that was done on a five phase induction motor with third harmonic injection. A test bench was developed where a three phase machine serves as disturbance generator of different frequencies. The control of the machines is based on multi scalar variables that ensures an independent control of the motor EMF and the rotor flux. For disturbance identification a speed observer system with load torque observer was implemented. It has been shown that the analysis of the estimated load torque provides sufficient results for disturbance identification. All investigations were done on an experimental setup.

Speed Sensorless AC Drive with Inverter LC Filter and Fault Detection Using Load Torque Signal

The industrial development in recent years has seen a major increase in the use of induction motors, whereby the cost has to be as low as possible and the lifetime as long as possible. To follow up this desire, investigations in this area have become very intense. For that reason, this paper presents a solution for driving an induction motor and simultaneous fault detection with no need for additional sensors. In order to achieve this target, an observer system is implemented and a torque estimation procedure is used for torque detection. An LC filter was installed at the inverter output to provide better THD of the current. The validation of the drive operation was achieved through simulation and experiments. To investigate possible faults, an artificial unbalance was introduced to the test bench, whereby the experiment was validated by a comparison of physical vibrations and estimated torque.

Metoda wektorowej modulacji szerokości impulsów pięciofazowego falownika napięcia

W artykule przedstawiono metode wektorowej modulacji szerokości impulsow pieciofazowego falownika napiecia. W takim przeksztaltniku zalączenie wektorow aktywnych powoduje jednoczesne formowanie dwoch wektorow napiecia wyjściowego. Komplikacja sterowania wynika z tego, ze polozenie obu wektorow napiecia oraz ich dlugości są wzajemnie zalezne. Rozwiązanie zaproponowane w pracy umozliwia jednak niezalezne formowanie dwoch wektorow napiecia o dlugościach i polozeniach zadanych przez nadrzedny uklad sterowania. Uzycie sześciu wektorow aktywnych umozliwia wymuszenie priorytetu ksztaltowania wektorow napiecia wyjściowego falownika o ograniczonym napieciu obwodu pośredniczącego.

Five-Phase Squirrel-Cage Motor. Construction and Drive Properties

This paper presents the simulation and experimental results of a five-phase squirrel-cage induction motor. The new machine has been designed to operate in a drive system with third harmonic rotor flux injection in order to improve the motor torque utilization. The motor structure, the mathematical model as well as the laboratory prototype have been described. The motor speed-torque characteristics and transients are elaborated Furthermore, the start-up possibility in the case of one or two stator winding faults has been shown as well. The idea of a closed loop speed control with increased load torque is presented.