Luiz H. S. C. Barreto

Interleaved-Boost Converter With High Voltage Gain

This paper presents an interleaved-boost converter, magnetically coupled to a voltage-doubler circuit, which provides a voltage gain far higher than that of the conventional boost topology. Besides, this converter has low-voltage stress across the switches, natural-voltage balancing between output capacitors, low-input current ripple, and magnetic components operating with the double of switching frequency. These features make this converter suitable to applications where a large voltage step-up is demanded, such as grid-connected systems based on battery storage, renewable energies, and uninterruptible power system applications. Operation principle, main equations, theoretical waveforms, control strategy, dynamic modeling, and digital implementation are provided. Experimental results are also presented validating the proposed topology.

High-Voltage Gain Boost Converter Based on Three-State Commutation Cell for Battery Charging Using PV Panels in a Single Conversion Stage

This paper presents a novel high-voltage gain boost converter topology based on the three-state commutation cell for battery charging using PV panels and a reduced number of conversion stages. The presented converter operates in zero-voltage switching (ZVS) mode for all switches. By using the new concept of single-stage approaches, the converter can generate a dc bus with a battery bank or a photovoltaic panel array, allowing the simultaneous charge of the batteries according to the radiation level. The operation principle, design specifications, and experimental results from a 500-W prototype are presented in order to validate the proposed structure.

A boost converter associated with a new nondissipative snubber

This paper presents a boost converter with a nondissipative snubber which provides a soft switching converter operation. This approach allows the main switch to work in a ZVS way and the auxiliary switch to work in a ZCS way. The nondissipative snubber is composed by two capacitors (resonant capacitors), one inductor (resonant inductor), one switch (auxiliary switch) and two diodes, one in series with the main switch and the other in series with the auxiliary switch. The complete operating principle, relevant equations, simulation results and experimental results are presented.

A variable speed wind energy conversion system connected to the grid for small wind generator

The wind energy system presented in this paper uses a permanent magnet generator connected to a three- phase semi-controlled rectifier. Although an acceptable THD and power factor result, the proposed converter is simple, cheaper, and robust. Additionally, a single-phase PWM inverter is also employed in the grid connection. The inverter uses a double hysteresis in the control of the current injected in the grid, what implies reduced switching losses. Analysis and partial experimental results are presented for a 5 kW prototype. At the final version of this paper, a more detailed theoretical analysis, simulation results, as well as experimental results at rated power are supposed to be presented.

A transformerless single phase on-line UPS with 110 V/220 V input output voltage

In this paper, it is proposed a new nonisolated UPS system configuration that allows the bypass circuit operation even if the input voltage is different from the output voltage. The UPS system is composed by an AC-DC/DC-DC three level boost rectifier/converter combined with a double half bridge inverter. This topology allows the reduction of some parameters that are commonly discussed in the nonisolated UPS systems such as size and cost, compared with others isolated UPS configurations for the same purpose. Also, the efficiency are improved due to reduced number of switches and batteries, as well as no low frequency isolation transformer is required to realize bypass operation because of the common neutral connection. Both stages of the proposed circuit operate in high frequency, using a passive nondissipative snubber circuit in the boost converter and IGBTs switches in the double half bridge inverter, with low conduction losses, low tail current and low switching losses. A simple and well-known control strategy is used. Principle of operation and experimental results for a 2.6 kVA laboratory prototype are presented to demonstrate UPS performance.

Analysis of a soft-switched PFC boost converter using analog and digital control circuits

This work presents a comparison between analog and digital (PIC16c73a) control types applied to the boost converter with a nondissipative snubber. Both control types use the bang-bang hysteresis current waveshaping control technique in order to achieve a quasi-unity power factor. The analog control applied presented a high power factor (0.998), high efficiency (92.87%), and low harmonic distortion [total harmonic distortion of current (THDI =2.84% and total harmonic distortion of current (THDV) =2.83%]. The digital control presented a high power factor (0.990), high efficiency (92.46%), and low harmonic distortion (THDI=5.09% and THDV=2.84%).

An optimal lossless commutation quadratic PWM Boost converter

This paper presents a PWM boost power converter, where the DC voltage conversion ratio has a quadratic dependence on the duty cycle, providing a large voltage step up (from 24 V to 160 V). By introducing two resonant networks, soft switching is achieved, providing highly efficient operating conditions for a wide load range at high switching frequencies.

High frequency isolation on-line UPS system for low power applications

In this paper, a new high frequency isolation on-line uninterruptible power supply (UPS) system is proposed as a viable solution for low power applications. Its composed by one half-bridge chopper that operates in open loop with fixed duty cycle, a step-up converter that operates in closed loop using the traditional average current mode control and a traditional full bridge voltage source inverter (VSI). The step-up converter control provides power factor correction to the system. The proposed circuit is suitable for the development of low power UPSs (less than 1 kVA) which few batteries are used. In such applications the battery bank voltage, can be 24 V, 36 V or 48 V. Principle of operation, as well as, experimental results for the UPS operating in both, grid and battery modes are presented. Accordingly to the experimental results for a 1 kVA assembled prototype, an efficiency of 81,3% is obtained for grid mode and 89,2% for the battery mode, confirming the effectiveness of the proposed configuration.

The bang-bang hysteresis current waveshaping control technique used to implement a high power factor power supply

This work reports the operation and development of a high power factor power supply that operates at high switching frequency. An optimum power factor correction is obtained using an ac-dc boost converter associated to a nondissipative snubber as a pre-regulator circuit, which presents reduced commutation losses. The same nondissipative snubber is associated to a Forward converter and then used as a dc-dc stage. The proposed switched mode power supply presents high power factor (0.998), high efficiency (91%), low harmonic content (current and voltage total harmonic distortion rates equal to 2.84% and 2.83%, respectively), and also satisfactory regulation. The converter has been theoretically analyzed, designed, simulated and implemented, where experimental results show that soft commutation in all switches is achieved.

Single stage high voltage gain boost converter with voltage Multiplier Cells for battery charging using photovoltaic panels

This paper presents a non-isolated high frequency DC-DC converter, which integrates a battery charger, photovoltaic panels, and a high voltage gain boost converter in a single conversion stage with soft-switching characteristic. The proposed topology uses voltage Multiplier Cells (MCs), leading do high voltage step-up. Also, the bidirectional behavior admits the DC bus to be generated via battery bank, or photovoltaic panels, or both, depending on the insulation condition. At last, experimental results validate the proposed topology, proving its effectiveness.