Transormerless inverters are attractive solution for the grid connected photovoltaic (PV) systems. Unfortunately, it has issues on galvanic isolation between PV systems to the grid. When the galvanic isolation disappears from the PV inverter, leakage currents will flow in a resonant circuit formed by the ground capacitance, the converter, the ac filter and the grid. In order to avoid the leakag...

This paper presents a new composite soft-switching configuration for single-phase inverters where power bridge leg modules are used. The presented configuration consists of only one inductor and one capacitor as well as two low-power-rated switches/diodes for full-bridge circuits. It can realize snubber functions and/or resonant zero-current switching at any load current for switches in power i...

The essential demand in high AC voltage testing is the availability of a test voltage with high quality, which is variable in amplitude and frequency. The power supply should not have any influence on the measurements – even the PDmeasurement and should be able to control a fault of the test objects insulation safely. These demands can be fulfilled using modern IGBT inverters. Two level voltage...

A new phase-controlled resonant inverter is obtained by paralleling the ac loads of two identical parallel resonant inverters. A phase shift between the drive signals of the two inverters controls the amplitude of the output voltage of the new inverter. A voltage-driven rectifier is used as an ac load of the inverter which results in a phase-controlled parallel resonant dc-dc converter. A frequ...

This paper presents the development of a resonant DC link inverter for an electric vehicle application. The resonant link frequency is approximately 70kHz and the inverter drives a low voltage 2.2kW AC induction motor. The IGBT inverter operates off a 240V DC supply and an active clamping circuit limits the resonant bus voltage to 500V. A synchronized PWM scheme is used to modulate the resonant...

A zero voltage switching based three phase voltage source inverter is presented. The soft switched resonant pole which is obtained by generalizing the conventional pseudo-resonant pole, is presented and suitable control and modeling methods are also described. The three phase resonant pole inverter is easily obtained by connecting three resonant poles to voltage source in parallel and it can be...

Bearing currents and shaft voltages of an induction motor are measured under hardand soft-switching inverter excitation. The objective is to investigate whether the soft-switching technologies can provide solutions for reducing the bearing currents and shaft voltages. Two of the prevailing soft-switching inverters, the resonant dc-link inverter and the quasi-resonant dc-link inverter, are teste...

In this paper, the performance of wireless operation of four-leg parallel inverters, at the presence of unbalanced nonlinear loads, is investigated. In order to control the parallel inverters, an inner current and external voltage control loops should be designed. In this paper, a proportional controller for the current internal loop as well as a proportional-resonant one for the voltage extern...

In this paper, a cascaded current–voltage control strategy is proposed for inverters to simultaneously improve the power quality of the inverter local load voltage and the current exchanged with the grid. It also enables seamless transfer of the operation mode from standalone to grid-connected or vice versa. The control scheme includes an inner voltage loop and an outer current loop, with both ...

The passively clamped quasi-resonant dc-link (PCQRL) inverter basic topology and other quasi-resonant inverters have been shown to be only partially compatible with pulsewidth modulation (PWM), due to a minimum dwell time created by the clamping mode in the inverter operation. This paper addresses this kind of modulation nonlinearity, employing the space-vector approach as a modeling tool. Clos...