Sang-Bong Yoo

Half-bridge series resonant inverter for induction heating applications with load-adaptive PFM control strategy

This paper presents an effective control scheme incorporated in a voltage-fed half-bridge series resonant inverter for induction heating applications, which is based upon a load-adaptive tuned frequency tracking control strategy using a PLL (phase locked loop) and its peripheral control circuit. The proposed control strategy ensures stable operation characteristics of the overall inverter system and ZVS (zero voltage switching) operation in spite of sensitive load parameters variations as well as power regulation, especially for nonmagnetic heating loads. The operating principle and the design procedure of the inverter system with the proposed control scheme are described. Also, simulation results and performance characteristics in the steady-state are shown as compared with experimental results for a prototype induction cooking system rated at 1.2 kW.

An improved full-bridge zero-voltage-transition PWM DC/DC converter with zero-voltage/zero-current switching of the auxiliary switches

In this paper, a novel full-bridge (FB) zero-voltage-transition (ZVT) pulsewidth modulation (PWM) DC/DC converter topology is proposed. The proposed FB-ZVT PWM DC/DC converter has zero-voltage switching (ZVS) of main switches for the entire line and load range and an advantage of achieving ZVS and zero-current switching of the auxiliary switches using the auxiliary network. The auxiliary network is simply composed of a saturable inductor, auxiliary capacitors, and auxiliary diodes. With the help of the proposed auxiliary network, the improved FB-ZVT PWM DC/DC converter has such characteristics as higher overall system efficiency and better utilization of the auxiliary switches compared with the conventional FB-ZVT PWM DC/DC converter. The operation principles are explained in detail and the several interesting simulation and experimental results verify the validity of the proposed circuit with an 83 kHz 1 kW prototype converter using insulated gate bipolar transistors.

A novel full-bridge ZVZCS PWM DC/DC converter with a secondary clamping circuit

This paper proposes a novel secondary clamping circuit for soft switching FB (full-bridge) PWM DC/DC converter. The proposed circuit eliminates the reflected output current which is reflected from the secondary side to the primary side so that it reduces the needless conduction losses of the primary side during the current circulating mode. Also, it ensures the zero-voltage/zero-current switching of the leading/lagging leg switches. The characteristics of the proposed clamping circuit are investigated and the validity is verified by the simulation and the experimental results.

Novel ZVZCS PWM DC-DC converters using one auxiliary switch

This paper presents new zero-voltage/zero-current-switching (ZVZCS) PWM DC-DC converters. The proposed soft-switching technique achieves ZVS and ZCS simultaneously at both turn-on and turn-off of the main switch and diode by using only one auxiliary switch. Also, this technique is suitable for not only minority but also majority carrier semiconductor devices. The auxiliary circuit of the proposed topologies is placed out the main power path, therefore, there are no voltage/current stresses on the main switch and diode. The operating principle of the proposed topologies is illustrated by a detailed study with a boost converter as an example. Theoretical analysis, simulation and experimental results are presented to explain the proposed schemes.

A novel secondary clamping circuit topology for soft switching full-bridge PWM DC/DC converter

This paper proposes a novel secondary clamping circuit for soft switching FB (full-Bridge) PWM DC/DC power converter. The proposed circuit eliminates the reflected output current which is reflected from the secondary side to the primary side so that it reduces the needless conduction losses of the primary side during the current circulating mode. Also, it ensures the zero-voltage/zero-current switching of the leading/lagging leg switches. The characteristics of the proposed clamping circuit are investigated and the validity is verified by the simulation and experimental results.

A novel three-level ZVS PWM inverter topology for high-voltage DC/DC conversion systems with balanced voltage sharing and wider load range

As the three-level (TL) ZVS PWM DC/DC converter operates like a full-bridge (FB) ZVS PWM DC/DC converter and the blocking voltage of each switching device is a half of the DC-link voltage, it is suitable for high input voltage applications. However, it has some problems as follows; the blocking voltage of each device is unbalanced and it causes the power loss of the inner switching devices to be increased. Also, it has a narrow load range so that the switching losses and the efficiency are reduced as it goes to the light load. This paper presents a novel TL ZVS PWM DC/DC converter, which can reduce the overvoltage of the outer switches, eliminates the unbalance of the voltage sharing between the switches at turn-off due to the stray inductances, and operate from no load to full load. The characteristics and the performances of the proposed TL ZVS PWM DC/DC converter are verified by simulation and experimental results.

A new class-D voltage source series-loaded resonant inverter topology considering stray inductance influences

A new class-D voltage source series-loaded resonant inverter topology which can reduce the influences of the stray inductance is proposed. In the conventional class-D inverter topology, the stray inductance not only results in an overvoltage which gives the voltage stresses to the switches, but also in high frequency resonant currents during the turnoff transients. The proposed class-D inverter is superior to the conventional class-D inverter with respect to the reduction of problems due to the stray inductance. It is also more suitable for high power and high frequency inverters. The characteristics and the validity of the proposed class-D inverter are verified by both simulation and experimental results.

Design considerations based on AC complex circuit analysis for LCL type series resonant converter with phase shift control

A simple AC complex circuit analysis for an LCL type series resonant power converter with phase shift control (PWM) method is proposed. Based on this analysis, a set of characteristic curves which allows an optimal design procedure for this power converter are shown, without increasing the voltampere rating of the tank circuit. In particular, inverter output peak current can be minimized in both full load and part load conditions. The presented design considerations can make the control range of output voltage quite wide, under loads varying from heavy to light, achieving turn-on with zero voltage switching (ZVS) operation. The detailed analysis and experimental results show the effectiveness of the proposed design algorithms.

New ZVZCS PWM DC-DC converters with one auxiliary switch

This paper presents new zero-voltage/zero-current-switching (ZVZCS) PWM DC-DC converters. The proposed soft-switching technique achieves ZVS and ZCS simultaneously at both turn-on and turn-off of the main switch and diode by use of only one auxiliary switch. Also, this technique is suitable for not only minority but also majority carrier semiconductor devices. The auxiliary circuit of the proposed topologies is placed out of the main power path, therefore, there are no voltage/current stresses on the main switch and diode. The operating principle of the proposed topologies is illustrated by a detailed study with a boost converter as an example. Theoretical analysis, simulation and experimental results are presented to explain the proposed schemes.

A modified ZVZCS commutation cell for all active switches in PWM converters

In this paper, a modified ZVZCS commutation cell with minimum additional components, which provides soft switching at both turn-on and turn-off of main and auxiliary switches as well as diodes in PWM converters, is presented. The proposed soft-switching technique is suitable for not only minority but also majority carrier semiconductor devices. The auxiliary switch of the proposed ZVZCS commutation cell is in parallel with the main switch, and therefore, there is no current stress on the main switch and diode. The operation principles of the proposed ZVZCS commutation cell are theoretically analyzed using the PWM boost converter topology as an example. Theoretical analysis, simulation and experimental results verify the validity of the PWM boost converter topology with the proposed ZVZCS commutation cell.