Marcello Mezaroba

A ZVS PWM inverter with active voltage clamping using the reverse recovery energy of the diodes

This paper presents a zero-voltage-switching (ZVS) pulsewidth modulated inverter with active voltage clamping using only a single auxiliary switch. The structure is particularly simple and robust. It is very attractive for single-phase high-power applications. Switching losses are reduced due to implementation of the simple active snubber circuit that provides ZVS conditions for all switches, including the auxiliary one. Its main features are: simple modulation strategy, robustness, low weight and volume, low harmonic distortion of the output current and high efficiency. The principle of operation for steady-state conditions, mathematical analysis and experimental results from a laboratory prototype are presented.

A ZVS PWM Half-Bridge Voltage Source Inverter With Active Clamping

This paper presents a zero-voltage (pulsewidth modulation) half-bridge inverter with active voltage clamping using only a single auxiliary switch. The structure is particularly simple and robust. It is very attractive for single-phase high-power applications. Switching losses are reduced due to implementation of the simple active snubber circuit that provides zero-voltage-switching conditions for all switches, which includes the auxiliary one. Its main features are simple modulation strategy, robustness, low weight and volume, low harmonic distortion of the output current, and high efficiency. The principle of operation for steady-state conditions, mathematical analysis, and experimental results from a laboratory prototype are presented.

A Simplified Control Technique for a Dual Unified Power Quality Conditioner

This paper presents a simplified control technique for a dual three-phase topology of a unified power quality conditioner-iUPQC. The iUPQC is composed of two active filters, a series active filter and a shunt active filter (parallel active filter), used to eliminate harmonics and unbalances. Different from a conventional UPQC, the iUPQC has the series filter controlled as a sinusoidal current source and the shunt filter controlled as a sinusoidal voltage source. Therefore, the pulse width modulation (PWM) controls of the iUPQC deal with a well-known frequency spectrum, since it is controlled using voltage and current sinusoidal references, different from the conventional UPQC that is controlled using nonsinusoidal references. In this paper, the proposed design control, power flow analysis, and experimental results of the developed prototype are presented.

Step-Up/Step-Down DC–DC ZVS PWM Converter With Active Clamping

This paper presents a regenerative step-up/step-down DC-DC zero-voltage-switching pulsewidth-modulation converter with active clamping. The switch losses are reduced due to the implementation of a simple active snubber circuit that provides soft commutation in all the switches of the converter. The theoretical analysis, basic equations, design methodology, and experimental results are shown in this paper. A control methodology to assure the output voltage regulation is also proposed. The main advantages of the proposed power converter are the small number of components, simplicity of the controller, robustness, small weight and size, and high efficiency.

Modeling and Digital Control of a Single-Stage Step-Up/Down Isolated PFC Rectifier

This paper presents the dynamic modeling and digital control of a single-stage isolated current rectifier with power factor correction based on the integration of full-bridge and flyback converters. This converter is designed to operate with adjustable output voltage so that it can operate in two distinct operation modes, depending on the input and output voltages. Therefore, small-signal state-space average models are obtained for the converter operating in step-down and step-up operation modes, and analysis and design of the digital control system are included for different operating points. Experimental results based on a 3-kW prototype are presented to validate the proposed control system under distinct conditions.

A ZVS PWM full-bridge inverter with active clamping technique using the reverse recovery energy of the diodes

This paper presents a ZVS PWM full bridge inverter with active voltage clamping technique that use the recovery energy of the diodes. The structure is particularly simple and robust because they use only a single auxiliary switch. Switching losses are reduced due to implementation of the simple active snubber circuit that provides ZVS conditions for all switches, including the auxiliary one. It is very attractive for single-phase high power applications. Its main features are: simple control strategy, robustness, lower weight and volume, lower harmonic distortion of the output current, and high efficiency. The principle of operation for steady-state conditions, mathematical analysis and experimental results from a laboratory prototype are presented.

A dual unified power quality conditioner using a simplified control technique

This paper presents a dual three-phase topology of unified power quality conditioner (UPQC) composed of two filters, a series active filter and a parallel active filter, aimed to compensate both, the current and voltage, harmonics and unbalance. Different from conventional UPQC, the dual UPQC has the series filter controlled as a sinusoidal current source and the parallel filter controlled as a sinusoidal voltage source. Therefore, the PWM controls of the dual UPQC deal with a well known frequency spectrum, since it is controlled using voltage and current sinusoidal references, differently from the conventional UPQC which is controlled using nonsinusoidal references. In this paper it is presented the analog control project and some experimental results of the developed prototype.

Emulation of nonlinear loads with energy regeneration

This paper presents an nonlinear load emulator for testing AC power supplies and power equipment with energy regeneration capability. The structure is based on back to back three-phase PWM voltage source inverter (VSI). To achieve power balance, an independent control strategy for both PWM VSI is proposed. Experimental results are presented to verify the emulator performance draining a linear and nonlinear current from an autotransformer and regenerating the energy to the utility grid.

Regenerative Undeland Snubber Using a ZVS PWM DC–DC Auxiliary Converter Applied to Three-Phase Voltage-Fed Inverters

This paper proposes an energy regeneration circuit for three-phase voltage-fed inverters using a modified Undeland snubber. The proposed system uses a quasi-square-wave zero voltage switching dc-dc auxiliary converter to regenerate the energy from snubber capacitor to the dc bus. The regenerative circuit uses a single active switch, and it operates independently of the three-phase inverter. Operation stages, theoretical waveforms, and a design methodology are presented. Experimental results based on a 4.5-kVA three-phase inverter prototype are included to validate the proposed topology.

Transformerless double-conversion UPS using a regenerative snubber circuit

This paper proposes a transformerless double-conversion UPS, which uses a regenerative Undeland snubber to regenerate the energy from switching losses to the dc bus. The regenerative circuit uses a simple buck-boost QSC (Quasi-Square-Wave) ZVS (Zero Voltage Switching) converter. This auxiliary commutation circuit includes only one active switch and its operation is independent of the UPS operation mode. A detailed methodology is included to design the main components of the auxiliary commutation circuit. Experimental results based on a 1.3 kVA prototype are presented for distinct operation modes to verify the feasibility of the proposed UPS.