Industrial Electronics
Asghar Taheri; Amir Ghasemian
Abstract
A direct torque control (DTC) controlled induction motor drive is presented in this paper. Quantization errors of current and voltage measurements are simulated and considered. To reduce the average quantization error and other offset errors of current and voltage measurement and eliminating the increasing ...
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A direct torque control (DTC) controlled induction motor drive is presented in this paper. Quantization errors of current and voltage measurements are simulated and considered. To reduce the average quantization error and other offset errors of current and voltage measurement and eliminating the increasing integrator errors, a random dither signal is added to the truncating analog to digital converter (ADC) outputs. In this method, the analog to digital converter (ADC) mean error is reduced to zero and therefore integrator output error is mitigated. Proposed quantization method can improve the digital converter result, thus this method can decrease the current measurement result. Proposed quantization method can improve the digital converter result, thus this method can decrease the current measurement result. Thus, the torque and flux ripple were be decreased. Proposed ditter injection method can be used in Digital signal processor (DSP) or FPGA implemented applications. Experimental results show the performance of proposed method.
Industrial Electronics
asghar taheri; Ahad Rasulkhani
Abstract
Multilevel inverters as a main component of electrical systems have been discussed over the past decade. Todays, improving their performance is one of the important challenges that has led to many studies in their topology and control system. In this paper, a new topology of symmetrical multi-level inverters ...
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Multilevel inverters as a main component of electrical systems have been discussed over the past decade. Todays, improving their performance is one of the important challenges that has led to many studies in their topology and control system. In this paper, a new topology of symmetrical multi-level inverters is provided that is able to feed inductive loads. The proposed topology has fewer power elements such as IGBTs, driver circuits, diodes and dc voltages. To increase the number of output voltage levels, several basic topology can be in cascaded structure. Comparison of proposed inverter topology with some conventional symmetrical topologies shows that the proposed topology has better efficiency in aspects of the number of IGBTs, losses and blocked voltage blocked in the switches. The performance and efficiency of the proposed inverter are verified by simulation and experimental results of a 9-level symmetrical inverter.The quality of a multi-level inverter specifies by its number of output levels.
Industrial Electronics
asghar taheri; Nader Asgari
Abstract
In this paper, a sliding mode control of LLC resonant dc-dc converter in low voltage and high current application is presented. The proposed controller operates at two fixed switching frequencies to the battery charger of electric vehicles. In resonant converter, because of the soft switching process, ...
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In this paper, a sliding mode control of LLC resonant dc-dc converter in low voltage and high current application is presented. The proposed controller operates at two fixed switching frequencies to the battery charger of electric vehicles. In resonant converter, because of the soft switching process, switching loss is negligible and converters can be designed at high frequencies to reduce the size, weight and price. To analyze this convertor the harmonic approximation method with state space equation is used. Taking advantage of the approximations used in order to avoid uncertainty, sliding mode control method is used. The mentioned convertor with the proposed controlled is exploited within three switching frequency bands that are lower than resonant frequency, resonant frequency and above resonant frequency. Due to the robustness of the sliding mode control, the output voltage regulation occurs with minimum distortion under a wide variation of input voltage, output voltage and output current. As a result, the battery life increases. In order to verify the results and effectiveness of the proposed converters, the prototype of LLC resonant converters Simulation and experimental results for the input voltage 300-420 V dc, output voltage 36-72 V dc and current output (0-11 A) is presented. The prototype achieves a peak efficiency value of 96%.