Haci Bodur

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.

An improved ZCT-PWM DC-DC converter for high-power and frequency applications

In this paper, an improved active resonant snubber cell that overcomes most of the drawbacks of the normal zero-current transition (ZCT) pulsewidth-modulation (PWM) dc-dc converter is proposed. This snubber cell is especially suitable for an insulated gate bipolar transistor (IGBT) PWM converter at high power and frequency levels. The converter with the proposed snubber cell can operate successfully with soft switching under light-load conditions and at considerably high frequencies. The operation principles, a detailed steady-state analysis, and a snubber design procedure of a ZCT-PWM buck converter implemented with the proposed snubber cell are presented. Theoretical analysis is verified with a prototype of a 5-kW and 50-kHz IGBT-PWM buck converter. Additionally, at 90% output power, the overall efficiency of the proposed soft switching converter increases to about 98% from the value of 91% in the hard-switching case.

A New Single-Phase Soft-Switching Power Factor Correction Converter

In this paper, single-phase soft-switching power factor correction (PFC) circuit is developed with a new active snubber cell. This active snubber cell provides zero-voltage transition turn ON and zero-current transition turn OFF for the main switch without any extra current or voltage stresses. Auxiliary switch is turned ON and OFF with zero-current switching (ZCS) without additional voltage stress. Although, there is a current stress on the auxiliary switch, it is decreased by diverting a part of the current to the output side with coupling inductance. The output current and voltage are controlled by the proposed PFC converter in very wide line and load range. This PFC converter has simple structure, low cost, and ease of control as well. In this study, a detailed steady-state analysis of the new converter is presented, and this theoretical analysis is verified exactly by 100 kHz and 300 W prototypes. This prototype has 98% total efficiency and 0.99 power factor with sinusoidal current shape.

A novel ZVT-ZCT PWM DC-DC converter

In this paper, a novel active snubber cell which is used in a boost type DC-DC converter is proposed. The proposed snubber cell provides zero voltage transition (ZVT) and zero current transition (ZCT) for the main switch of the converter. All of the semiconductor devices turn on and off under soft switching. The converter has a simple structure and minimum number of components. Steady state analysis of the converter is presented, and theoretical analysis is verified by a prototype of a 1 kW and 100 kHz boost converter

Universal motor speed control with current controlled PWM AC chopper by using a microcontroller

In this paper, a universal motor speed control system with a PWM AC chopper is introduced. Operation principles of the control system, which is realized with a microcontroller, are presented. Mathematical model of the universal motor and PWM AC chopper is derived and the behavior of the system is studied by simulation. Mains power factor, motor speed, and current are analyzed for different load conditions. Harmonic analysis of the motor current and voltage are given and compared with phase control technique. Experiments are made to verify the effectiveness of the system. According to the experimental results, both simple hardware design and good speed response can be attained.

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.

A New ZVT Snubber Cell for PWM-PFC Boost Converter

In this paper, a new zero-voltage transition (ZVT) snubber cell is developed for pulse width modulated (PWM) and power factor corrected (PFC) boost converters operating in continuous conduction mode. A new family of PFC boost converter implemented with this new ZVT snubber cell is proposed. In this new PFC boost converter, the main switch is turned-on perfectly with ZVT and turned-off under zero-voltage switching (ZVS). Besides, the auxiliary switch is turned-on under zero current switching and turned-off under ZVS. The main and all auxiliary diodes are operating under soft switching. During ZVT operation, the switching energies on the snubber inductance are transferred to the output by a transformer, and so the current stresses of the inductance and the auxiliary switch are significantly decreased. Also, this transformer ensures the usage of sufficient capacitors for ZVS turning off of the main and auxiliary switches. The main switch and main diode are not subjected to any additional voltage and current stresses. In this study, a detailed steady-state analysis of the proposed new ZVT-PWM-PFC boost converter is presented and this theoretical analysis is verified by a prototype with 100 kHz and 2 kW.

A new ZVT–ZCT quasi-resonant DC link for soft switching inverters

In this article, the new ZVT–ZCT Quasi-Resonant DC Link, which ensures zero crossings at any time required for soft switching (SS) and provides zero voltage transition (ZVT) turn-on and zero current transition (ZCT) turn-off together for the main switch of active snubber cell in pulse width modulated or space vector modulated operation of inverter is presented. The new circuit combines the most desirable features of the circuits presented previously and overcomes most drawbacks of these circuits by using only one auxiliary switch with fewer other components. Consequently, new ZVT–ZCT Quasi-Resonant DC Link, which is verified by a prototype of a 1.2 kW and 50 kHz circuit, is analysed in detail. All semiconductor devices operate under SS, the main switch is subjected to no additional voltage and current stresses, and the stress on the auxiliary switch is very low in the proposed new inverter.

A comparative study of dual half-bridge inverter topologies used in induction cooking

An induction heating appliance used for cooking includes more than one inductor, each one being controlled by a separate inverter system. In this paper a comparison is performed between recently introduced two inverter topologies used in induction cookers. The topologies considered are the capacitor voltage clamped dual half-bridge series-resonant inverter (CVCDHB-SRI), and dual half-bridge series-resonant inverter (DHB-SRI). The advantage of these techniques is eliminating one switching device. Both of them are designed for same specifications. The comparison is based on criteria such as maximum rates of voltage and current values that device must withstand, and the power drawn from the source, and the electromagnetic emissions.

A new forward-flyback based single switch single stage PFC converter

In this study, a new forward-flyback based single switch single stage power factor correction (PFC) converter is presented. This circuit provides PFC, direct power transfer (DPT) and tight output voltage regulation with only single switch and controller. The switch turns on with zero current switching (ZCS) but turns off with hard switching. In this study a detailed steady state analysis of the new converter is presented and the theoretical analysis is verified for 100 kHz and 100 W simulation results with PSIM programme.