Mostafa Khazraei

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Two active capacitor voltage balancing schemes are proposed for single-phase (H-bridge) flying-capacitor multilevel converters. They are based on the circuit equations of flying-capacitor converters. Consequently, they can be implemented using straightforward control rules. In particular, the first technique is based on an algorithm which follows the(More)
Multilevel power electronic converters are the converter of choice in medium-voltage applications due to their reduced switch voltage stress, better harmonic performance, and lower switching losses. Although it has received little attention, the flying-capacitor multilevel converter has a distinct advantage in terms of its ease of capacitor voltage(More)
The deployment of a single-phase, multilevel flying capacitor converter as a 1.5-kW active rectifier is discussed in this paper. The challenges associated with this approach include providing unity power factor, regulating the dc output voltage, and maintaining balanced voltages across the flying capacitors. In such applications, the input current is(More)
In this paper, a new method to control multilevel converters is proposed. The considered multilevel converter consists of a three-phase three-level diode-clamped converter (main converter). Two H-bridge cells are then connected in series with each output phase of the main converter. The operation of the main converter and one of the cascading Hbridge cells(More)
This paper describes a research conducted on a single-phase flying capacitor active rectifier. An online process that reduces the total number of switching events, which leads to a reduction of switching losses in the converter, is introduced. This method is based on redundant state selection, which is used to regulate the voltage of flying capacitors. The(More)
This paper addresses the stability issues and some control solutions in solid-state transformers (SST). An SST is built using three cascaded stages, including an ac-dc rectifier, a dual active bridge (DAB) converter, and a dc-ac inverter. Multistage cascaded converters are highly prone to instabilities due to the interaction between stages. Hence, the(More)
Modified projected cross point control (PCPC) is introduced and discussed in this paper. Compared to the existing PCPC method, the hardware implementation of the proposed modified method is simpler. This modified PCPC method benefits from the advantages of traditional fixed- and variable-frequency current mode control approaches. For instance, as argued in(More)
In this paper, the small-signal analysis of the modified projected cross point control (PCPC) method is investigated. Modified PCPC is a new current-mode control approach which benefits from several advantages over common current-mode control methods such as peak current-mode control (PCMC) and average current-mode control (ACMC). Followed by the(More)
Projected cross point control (PCPC) is a new current-mode control approach which has been recently introduced. The PCPC method benefits from the advantages of traditional fixed-frequency and variable-frequency current-mode control methods. For instance, while PCPC is a fixed-frequency approach, it is stable for the entire range of the duty cycle similar to(More)