Jae-Eul Yeon

Multi-phase interleaved LLC-SRC and its digital control scheme

This paper proposes a new 3-phase interleaved LLC resonant DC-DC converter and its control scheme. The proposed circuit consists of three conventional interleaved LLC resonant DC-DC converters and each converter operates with π/3 of phase difference respectively. Therefore the current ripple of the output capacitor can be significantly reduced and the life cycle of the converter will be extended. To verify the validity of the proposed converter and digital scheme, an experiment with a prototype 1kW (12V/84A) DC-DC converter was implemented and its results are presented in this paper.

Reliability improvement of FB inverter in HID lamp ballast using UniFET™ II MOSFET family

This paper introduces a newly developed UniFETTM II MOSFET family of which the body diode characteristic has been highly improved and presents its effectiveness for the mixed frequency switching inverter leg in the HID lamp ballast. Its reverse recovery time, Trr of the body diode is 35 nsec and the peak value of reverse current, irr is also much smaller than that of the typical MOSFET and even smaller than FRDs. Therefore, it can ensure the better reliability in the switching inverter applications in which the performance of the MOSFET body diode is significant. In order to verify the validity, an experiment with an 150W HID lamp ballast was implemented and its results and effectiveness are presented in this paper.

A novel average burst-duty control method for the dimming of induction lamps

In this paper, a new dimming algorithm for the electronic ballast of an electrodeless fluorescent lamp is proposed. The proposed method is based on the burst dimming method that controls the duty ratio for the two switches of the electronic ballast by intermittently modulated pulse signal. This paper presents a fully digital circuit using an erasable programmable logic device (EPLD). To verify the validity of the proposed method, the implemented control circuit was applied to the electronic ballast for a 100 W electrodeless fluorescent lamp. As a result, a dimming method with a wide illumination range from 5 to 100% was obtained

A new high voltage shorted-anode IGBT with intrinsic body diode improves performance of single-ended induction cooker

Nowadays the field-stop (FS) IGBT provides lower saturation voltage drop and lower switching losses than the conventional non-punch-through (NPT) IGBT, making the FS IGBT well suited for induction heating (IH) applications. A relatively recent improvement in the FS IGBT - the integration of an antiparallel diode on the IGBT die through use of the shorted-anode (SA) technology - made the FS IGBT even better for IH designs. The aim of this paper is to demonstrate the effectiveness of Fairchild semiconductors second generation FS SA trench IGBT. Although the new device combines both IGBT and body diode functions, it can provide better performances by means of an advanced field stop trench IGBT technology. The single-ended (SE) resonant inverter for induction cooking application is analyzed and experiments for two 2kW SE induction cookers were carried out to verify the validity of new IGBT.

Fully digital controlled electronic ballast for electrode-less lamps

This Paper presents digital control based and remote controlled electronic ballast for electrode-less lamps. In order to control the power of lamp driven by high-frequency electronic ballast, remote control is necessary. For the group lighting system, especially, wireless remote control using RF modem is proper. In this paper, 2.4-GHz ISM band RF modem based remote controlled electronic ballast is proposed. However, the cost of RF modem is relatively expensive as compare with the cost of electronic ballast. For the economic realization, one-controller two-lamps system is proposed. And the proposed control circuit of the ballast is implemented with fully digital circuit using low cost 16-bit DSP and small size EPLD. Detailed algorithms for the power control and protections for the commercial electronic ballast are described. Finally, the wire and wireless linked group lighting system using the proposed ballast is introduced.

Effectiveness of FRFET® MOSFETs for the CCFL inverters in LCD TVs

For the backlighting of most LCD panels such as TVs and monitors today, CCFL (cold cathode fluorescent lamp) is widely used because it can provide both low cost manufacturing and high quality color gamut. To illuminate the CCFL, half-bridge or full-bridge resonant inverters are necessary. Although resonant inverters can work under the ZVS condition when the PFM (pulse frequency modulation) method is applied, most major LCD manufacturers adopt the PWM (pulse width modulation) method to control their LCDpsilas CCFL inverter because not only the color gamut might be varied but also its stability will be unstable when the inverter is operated by the PFM method due to its incremental resistance according to the varying the switching frequency. In the cases where CCFL inverter works with PWM method, the hard switching operation is inevitable and the additional diodes must be required because the reverse recovery behavior of the MOSFETpsilas body diode is inferior to FRD (fast recovery diode), which causes a large amount of switching loss and it will even make the system failure due to the shoot-through current. In this paper, a newly improved FRFET MOSFET with superior reverse recovery characteristics is introduced and the experimental results for applying it to 42rdquo LCD TV are presented. From these results, the validity of the new FRFET has been verified. The reverse recovery time is shorter than 40 ns and irr is also much smaller than the typical power MOSFETs, which are sufficient to prevent the MOSFETpsilas failures without the external diodes in CCFL BLU (back light unit) system.

A fully digitally controlled power supply unit for wireless remote controlled LED lighting systems

This paper presents a fully digital controlled power supply unit for the wireless controlled dimmable LED lighting system. The proposed power supply designed using fly-back converter, which is directly controlled by a microprocessor. Although the proposed circuit does not sense the AC input current and has not AC input voltage feed-forward, it can achieve high power factor. The proposed power supply directly regulates the output power for LED loads using the PWM and PFM control of the fly-back converter without additional regulator. For a wireless remote control function, the Zigbee modem is equipped in the proposed power supply. A prototype set-up has been built and tested. Through the experiment with a prototype set-up, the usefulness of the proposed power supply is verified.

A microprocessor based single stage power supply using fly-back converter for LED lightings

This paper presents a single stage power supply for LED lightings. The proposed power supply designed using fly-back converter topology, which is directly controlled by a microprocessor. Although the proposed circuit does not sense the AC input current and has not AC input voltage feed-forward, it can achieve high power factor. The proposed power supply directly regulates the output power for LED loads using the PWM and PFM control of the fly-back converter without additional regulator. A prototype set-up has been built and tested. Through the experiment with a prototype set-up, the validity of the proposed circuit is verified.

A 3.6kW single-ended resonant inverter for induction heating applications

The single-ended (SE) resonant inverter is a type of class E parallel resonant inverter and popularly used in many IH applications due to its lower cost structure and relatively high efficiency. However its maximum power rating should be limited because the resonant voltage of SE resonant inverter increases as its power increases. Consequently the maximum power rating of SE resonant inverter should be limited up to around 2kW. This paper proposes an interleaved single-ended resonant inverter for the induction heating applications. The proposed inverter can provide two times higher output power than the conventional single-ended resonant inverter by the alternative operation of two inverters. A burst mode control enhances the power control range from very light load to full load and can improve efficiency.

Field stop shorted anode trench IGBT for induction heating appliances

This paper introduces a newly developed field stop shorted anode trench IGBT with intrinsic body diode like power MOSFETs, and presents its effectiveness for the single ended resonant inverter in induction heating applications. Although the new device combines both IGBT and body diode functions, it can provide better performances by means of an advanced field stop trench IGBT technology. The effectiveness of the new device is validated in an experiment using 1.8kW single-ended induction heating resonant inverter.