Ismail Aksoy

A new ZVT-ZCT-PWM DC-DC converter

In this paper, a new active snubber cell is proposed to contrive a new family of pulse width modulated (PWM) converters. This snubber cell provides zero voltage transition (ZVT) turn on and zero current transition (ZCT) turn off together for the main switch of a converter. Also, the snubber cell is implemented by using only one quasi resonant circuit without an important increase in the cost and complexity of the converter. New ZVT-ZCT-PWM converter equipped with the proposed snubber cell provides most the desirable features of both ZVT and ZCT converters presented previously, and overcomes most the drawbacks of these converters. Subsequently, the new converter can operate with soft switching successfully at very wide line and load ranges and at considerably high frequencies. Moreover, all semiconductor devices operate under soft switching, the main devices do not have any additional voltage and current stresses, and the stresses on the auxiliary devices are at low levels. Also, the new converter has a simple structure, low cost and ease of control. In this study, a detailed steady state analysis of the new converter is presented, and this theoretical analysis is verified exactly by a prototype of a 1-kW and 100-kHz boost converter.

A Novel ZVT-ZCT-PWM Boost Converter

In this study, a new boost converter with an active snubber cell is proposed. The active snubber cell provides main switch to turn ON with zero-voltage transition (ZVT) and to turn OFF with zero-current transition (ZCT). The proposed converter incorporating this snubber cell can operate with soft switching at high frequencies. Also, in this converter all semiconductor devices operate with soft switching. There is no additional voltage stress across the main and auxiliary components. The converter has a simple structure, minimum number of components, and ease of control as well. The operation principle and detailed steady-state analysis of the novel ZVT-ZCT-PWM boost converter are given. The presented theoretical analysis is verified exactly by a prototype of 100 kHz and 1 kW converter. Also, the overall efficiency of the new converter has reached a value of 97.8% at nominal output power.

A Bidirectional Nonisolated Multi-Input DC–DC Converter for Hybrid Energy Storage Systems in Electric Vehicles

To process the power in hybrid energy systems using a reduced part count, researchers have proposed several multiinput dc-dc power converter topologies to transfer power from different input voltage sources to the output. This paper proposes a novel bidirectional nonisolated multi-input converter (MIC) topology for hybrid systems to be used in electric vehicles composed of energy storage systems (ESSs) with different electrical characteristics. The proposed converter has the ability to control the power of ESSs by allowing active power sharing. The voltage levels of utilized ESSs can be higher or lower than the output voltage. The inductors of the converter are connected to a single switch; therefore, the converter requires only one extra active switch for each input, unlike its counterparts, hence resulting in reduced element count. The proposed MIC topology is compared with its counterparts concerning various parameters. It is analyzed in detail, and then, this analysis is validated by simulation and through a 1-kW prototype based on a battery/ultracapacitor hybrid ESS.

A New Parallel Resonant DC Link for Soft Switching Inverters

In this article, a new parallel resonant DC link (PRDCL) that provides soft switching (SS) and pulse width modulated (PWM) operation for inverters is presented. The new PRDCL ensures zero crossings for a time period, and at any time required for SS and PWM operation of the inverters, respectively. Moreover, the proposed PRDCL is realized by using only one auxiliary active switch, has a simple structure and ease of control, and operates under SS conditions. All switches in the soft switching inverters (SSI) equipped with the new PRDCL operate with soft switching, and are subjected to no additional voltage and current stresses. A detailed steady-state analysis of the proposed PRDCL is presented, and this theoretical analysis is verified by a prototype of a 250 V, 50 kHz and 1250 W circuit.

Analysis, Design, and Implementation of a Zero-Voltage-Transition Interleaved Boost Converter

This study proposes a novel zero voltage transition (ZVT) pulse width modulation (PWM) DC–DC interleaved boost converter with an active snubber cell. All the semiconductor devices in the converter turn on and off with soft switching to reduce the switching power losses and improve the overall efficiency. Through the interleaved approach, the current stresses of the main devices and the ripple of the output voltage and input current are reduced. The main switches turn on with ZVT and turn off with zero voltage switching (ZVS). The auxiliary switch turns on with zero current switching (ZCS) and turns off with ZVS. In addition, the snubber cell does not create additional current or voltage stress on the main switches and main diodes. The proposed converter can smoothly achieve soft switching characteristics even under light load conditions. The theoretical analysis and operating stages of the proposed converter are made for the D > 50% and D < 50% modes. Finally, a prototype of the proposed converter is implemented, and the experimental results are given in detail for 500 W and 50 kHz. The overall efficiency of the proposed converter reached 95.5% at nominal output power.

A new Zero-Voltage-Transition PWM DC-DC boost converter

In this paper, a new ZVT-PWM DC-DC boost converter is proposed. In the proposed new converter, the main switch turns on under Zero Voltage Transition (ZVT) and turns off under Zero Voltage Switching (ZVS). Besides, the auxiliary switch turns on under Zero Current Switching (ZCS) and turns off under Zero Current Transition (ZCT). Also, the other semiconductor elements softly turn on and turn off under ZVS or ZCS. Another feature of proposed converter is that there is no additional current or voltage stress on the main switch and main diode. Also, there is no additional voltage stress on the auxiliary switch and the auxiliary diodes. The proposed new converter operates even under light load conditions and it has advantages as the simple structure, the low cost and easy control. Firstly, the theoretical analysis of the proposed converter is made. Then, the operating stages, the key waveforms and the simulation results of the new converter operated for 500 W and 40 kHz is given in detail.

A new soft switching three level T-type inverter

In this paper, a new soft switching T-type three level inverter is proposed. The proposed new converter provides for main switches to turn on with Zero Voltage Transition (ZVT) and turn off with Zero Voltage Switching (ZVS) without any voltage or current stresses. Also, the proposed new converter provides Soft Switching (SS) for all semiconductors. Besides, Electro Magnetic Interference (EMI) noises are decreased by soft switching cell. The proposed converter has a low cost, ease of control and simple structure. The theoretical analysis of converter is clarified and the operating stages are given in detail. The simulation results of converter are obtained for 3.3 kW and 50 kHz by PSIM program. It is observed that the simulation results and theoretical analysis of converter are perfectly suitable with each other.

Comparison of SVPWM, SPWM and HCC control techniques in power control of PMSG used in wind turbine systems

In this paper, the performance of space vector pulse width modulation (SVPWM), sinusoidal pulse width modulation (SPWM) and hysteresis current control (HCC) control techniques used in power control with back to back converter of permanent magnet synchronous generator used in wind turbines are comparatively analyzed in terms of dynamic response, total harmonic distortion (THD), torque ripple and current ripple. Furthermore, SVPWM and SPWM are compared in terms of the using DC link voltage. Analysis of system is realized with MATLAB/Simulink program. There is not paper that together of these three control techniques are compared in terms of common results or values in literature. Permanent magnet synchronous generator (PMSG) is used in simulations is surface mounted, bipolar and its power is 1.8 kW. However, PMSMs energy transmission to grid is made with Field Oriented Control (FOC). According to analysis results, it has been observed that SVPWM generally has more efficient results than both HCC and SPWM control technique. Also, it is observed that SVPWM can produce about 15 percent higher than SPWM in output voltage.

A new reduced voltage stress ZVT-ZVS PWM full-bridge dc-dc converter

A new reduced voltage stress soft switching PWM current fed Full-Bridge DC-DC converter for fuel cells and photovoltaic cells applications is proposed in this study. The snubber cell provides Zero Voltage Transition (ZVT) turn on and Zero Voltage Switching (ZVS) turn off together for main switches in the converter. The voltage stresses of the main the switches are reduced and turning them off became better by adding an extra passive component. Besides, all components operate under soft switching, the current or voltage stresses on the auxiliary component are quite in acceptable level, and the main devices do not have any additional current stresses. In addition, the simplified structure makes the novel converter easy to control. Detailed analysis and synthesis of the new converter is introduced, and usefulness of the design is confirmed by simulation studies of a 1.5 kW and 25 kHz full bridge converter.

A soft switching power factor correction interleaved AC-DC boost converter

In this paper, a novel soft switching power factor correction (PFC) interleaved AC-DC boost converter is proposed. In the proposed novel converter, all of the semiconductor devices operate with soft switching. The main switches turn on with zero voltage transition (ZVT) and turn off with zero current transition (ZCT) without any extra voltage or current stresses. Auxiliary switch turns on with zero current switching (ZCS) and turns off with zero voltage switching (ZVS). Besides, the main diodes turn on with zero voltage switching (ZVS) and turns off with ZCS without any extra voltage or current stresses. Owing to interleaved structure, the ripple of the input current and output voltage is reduced. So, power factor quality is significantly good. The output current and voltage are controlled in wide line and load range. The theoretical analysis of converter is clarified and the operating modes are given in detail. The simulation results of converter are obtained for 1.5 kW and 100 kHz. It is observed that the semiconductor devices operate with soft switching (SS) perfectly. Also, the novel proposed converter has 0.99 power factor with sinusoidal current shape.