Farhad Ashrafzadeh

Space Vectors Modulation for Nine-Switch Converters

Recently, nine-switch inverter and nine-switch-z-source inverter have been proposed as dual output inverters. In this paper, the space vector modulation (SVM) of nine-switch inverter and nine-switch-z-source inverter is proposed. The proposed method increases the sum of modulation indices up to 15% in contrast with the conventional, scheme in which the sum of modulation indices is equal or less than one. The extra voltage available for a given input dc-voltage, translates to a higher torque-a critical factor for defining the capacity of products in marketplace. Also, in order to further reduce the cost of power devices and also thermal heat effect, and to reduce the number of semiconductor switching, specific SVM switching pattern is presented. This feature will be advantageous for high-power inverter applications where cost and efficiency are key decision factors. Furthermore, a novel SVM is proposed for minimizing total harmonic distortion. The performance of the proposed SVM for both nine-switch inverter and nine-switch-z-source inverter is verified by simulation. Experimental results validate the simulation results as well as the superiority of the proposed SVM.

A Dual-Input–Dual-Output Z-Source Inverter

This paper presents a new z-source inverter with two AC outputs and two DC inputs. This inverter is based on the z-source inverter and nine-switch inverter. The presented inverter can control amplitude, frequency, and phase of both AC outputs and also control current of both DC inputs. Input dc voltages are boosted to the required level. Also, both outputs continue their operation, even if one of the input voltages is zero. Performance of the proposed inverter is verified by simulation and experimental results.

A novel space vector modulation for nine-switch converters

Recently, nine-switch inverters and nine-switch zsource inverters have been proposed as dual output inverters. In this paper, a new space vector modulation (SVM) for nineswitch and nine switch z-source inverter is proposed. The proposed method increases the sum of modulation indices about 15% in contrast with the conventional scheme in which the sum of modulation indices is equal or less than one. The extra available voltage for a given input dc-voltage, translates to a higher torque. Also, in order to further reduce the cost of power devices and also thermal heat effect reduce number of semiconductor switching, specific SVM switching pattern is presented. This feature will be advantages for high power inverter applications. The performance of the proposed SVM for both nine-switch inverter and nine-switch z-source inverter is verified by simulation and experimental results.

Unbalanced Load Estimation Algorithm Using Multiple Mechanical Measurements for Horizontal Washing Machines

In horizontal washing machines, accurate estimation of unbalanced loads, including their magnitudes and locations in washing drums, is always required to achieve quiet highspeed spinning operations. Many estimation algorithms have been developed for the purpose and their estimation accuracy needs to be evaluated in real laundry processes. Nevertheless, lack of true information on the unbalanced loads during the process against which different algorithms could compare makes the evaluation a nontrivial task: it is very hard, if it is not impossible, to directly quantify the actual unbalanced load magnitude/location while the laundry is being washed. To tackle the problem, we use multiple mechanical measurements from laser displacement sensors, accelerometers and load cells which are installed in different locations on a horizontal washing machine, to derive true unbalanced load information inside a drum. Neural networks with PCA preprocessing are employed for the estimation and experiments have been designed to train and test the neural networks. Performances of the neural network-based estimation algorithm are reported.

Dual-input dual-output z-source inverter

This paper presents a new z-source inverter with two AC outputs and two DC inputs. This inverter is based on the z-source inverter and nine-switch inverter. The presented inverter can control amplitude, frequency and phase of both AC outputs and also control current of both DC inputs. Input DC voltages are boosted to the required level. Also, both outputs continue their operation, even if one of the input voltages is zero. Performance of the proposed inverter is verified by simulation and experimental results.