Alan Joseph

Constant boost control of the Z-source inverter to minimize current ripple and voltage stress

This paper proposes two constant boost-control methods for the Z-source inverter, which can obtain maximum voltage gain at any given modulation index without producing any low-frequency ripple that is related to the output frequency and minimize the voltage stress at the same time. Thus, the Z-network requirement will be independent of the output frequency and determined only by the switching frequency. The relationship of voltage gain to modulation index is analyzed in detail and verified by simulation and experiments.

Z-source inverter for motor drives

This paper presents a Z-source inverter system and control for general-purpose motor drives. The Z-source inverter system employs a unique LC network in the dc link and a small capacitor on the ac side of the diode front end. By controlling the shoot-through duty cycle, the Z-source can produce any desired output ac voltage, even greater than the line voltage. As a result, the new Z-source inverter system provides ride-through capability during voltage sags, reduces line harmonics, improves power factor and reliability, and extends output voltage range. Analysis, simulation, and experimental results will be presented to demonstrate these new features.

Low cost fuel cell converter system for residential power generation

The high installation cost is the major obstacle of the commercialization of the solid oxide fuel cell for distributed power generation. This paper presents a new low cost 10-kW converter system to overcome this obstacle. The proposed system consists of an isolated dc-dc converter to boost the fuel cell voltage to 400 V dc and a pulse-width modulated inverter with filter to convert the dc voltage to two split-phase 120-V ac. The dc-dc converter uses phase shifting to control power flow through a transformer with a metal oxide semiconductor field effect transistor full bridge on the low voltage side and a voltage doubler on the high voltage side. One IPM is used to realize the voltage doubler and the dc-ac inverter. Compared to the existing fuel cell converter systems, the proposed circuit has low cost, less component count, smaller size, and reduced dc-dc converter peak current. Simulation and experimental results are demonstrated.

Comparison of traditional inverters and Z-source inverter for fuel cell vehicles

In this paper, three different inverters: conventional pulsewidth modulation (PWM) inverter, dc-dc boosted PWM inverter, and Z-source inverter were investigated and compared for fuel cell vehicle application. Total switching device power, passive components requirement, and constant power speed ratio of each of these inverters were calculated. For purposes of comparison, an example of the total switching device power, requirement of passive components, the constant power speed ratio, and the efficiencies of the different inverters for fuel cell vehicle powered by the same fuel cell were conducted. The comparisons show that the Z-source inverter is very promising in applications when the boost ratio is low (1-2).

Low cost fuel cell inverter system for residential power generation

The high installation cost is the major obstacle of the commercialization of the solid oxide fuel cell (SOFC) for distributed power generation. This paper presents a new low cost 10 kW inverter system to overcome this obstacle. The proposed system consists of an isolated DC-DC converter to boost the fuel cell voltage to 400 V DC and a PWM inverter with filter to convert the DC voltage to two split-phase 120 V AC. The DC-DC converter uses phase shifting to control power flow through a transformer with a MOSFET full bridge on the low voltage side and a voltage doubter on the high voltage side. One IPM is used to realize the voltage doubter and the DC-AC inverter. Compared to the existing fuel cell inverter systems, the proposed circuit has low cost, less component count, smaller size, and reduced DC-DC converter peak current. Simulation and experimental results are demonstrated.

Comparison of Traditional Inverters and Z-Source Inverter

In this paper, three different inverters-traditional PWM inverter, dc/dc boosted PWM inverter, and Z-source inverter were investigated and compared using fuel cell vehicle and photovoltaic domestic application as examples. Total switching device power, passive component requirement, and constant power speed ratio of each of these inverters were calculated. For purposes of comparison, an example of the total switching device power, requirement of passive components, and the constant power speed ratio of the different inverters for fuel cell vehicle powered by the same fuel cell and loaded by the same motor were conducted. The efficiencies of different systems for traction drive and photovoltaic residential application are also compared. The comparisons show that the Z-source inverter is very promising

Design and Development of a 50kW Z-Source Inverter for Fuel Cell Vehicles

A detailed design process of the Z-source inverter is presented in this paper. A DC rail clamp circuit is used to reduce the overshoot of the device during turn off. The thermal and 3-D design process is gone through, and the loss calculation of the inverter is discussed, which is different from traditional PWM inverters. A 50 kW inverter for fuel cell vehicle is developed to demonstrate the validity of the design process. Experimental results confirmed the design process and demonstrated the high efficiency characteristic of the Z-source inverter

Development and Test of a 260 kVA Inverter with a Passive Soft-Switching Snubber

A 260 kVA inverter has been developed with a passive soft-switching snubber. The main circuit configuration and prototyping are described. Optimization of the passive soft-switching snubber parameters has been made to control the voltage overshoot across the switches, minimize snubber and inverter losses, and effectively limit dv/dt and di/dt during activation. An efficiency higher than 98.5% has been achieved as well as other prospected features. Experimental results are given to demonstrate the validity and features of the inverter.