Search

This paper presents an optimal lowest-voltage-switching technique for boundary mode power factor correction (PFC) converters. The proposed approach minimizes the switching loss of the power MOSFET without additional discrete components. Optimal zero-voltage-switching or valley-switching can be achieved for universal input range. The gate driver delay can also be taken into account. A boundary mode boost PFC converter with the proposed optimal switching technique has been implemented using a 0.5-μm N-well process. Experimental results show that the proposed approach can realize optimal soft switching, and improve the efficiency of the boost PFC converter. The proposed lowest-voltage-switching technique can be applied to other resonant converters as well. [ABSTRACT FROM AUTHOR]

Source switching circuit with low-gate-driving loss in high-voltage buck light emitting diode (LED) driver is proposed in this study. Source switching circuit comprises of a high-voltage power metal-oxide semiconductor field-effect transistor (MOSFET) (HVMOS) and a low-voltage power MOSFET (LVMOS) in series, a capacitor and a Zener diode. By switching the HVMOS by different source voltage and constant gate voltage, it recycles gate charges of HVMOS to reduce gate-driving loss. Gate charges are recycled in the capacitor when LVMOS is turning off, and can be reused when LVMOS is turning on. This circuit also provides a new power feeding route for control chip, and power consumption is relatively low on the proposed route. The power feeding route also improves power efficiency. With a 12 W LED load, the experiment shows that the efficiency of the proposed driving circuit is improved by 3.7% with 156 V input voltage and 4.8% with 326 V input voltage compared with the converter using single HVMOS. [ABSTRACT FROM AUTHOR]

A new zero-voltage-switching (ZVS) control approach is presented for pulsewidth modulation (PWM) buck converters under discontinuous conduction mode (DCM)/continuous conduction mode (CCM) boundary. This proposed technique compensates for control circuit delay, and hence, turns on power MOS at the instant exactly when drain-to-source voltage becomes zero. No complicated timing calculation circuits or additional external components are required. This proposed integrated ZVS control can be applied to other dc-dc converters as well. The corresponding circuit analysis, implementation, and die photograph are presented in this paper. Simulation and experimental results for an example circuit with VIN of 5 V and VOUT of 3.3 V. reveal that buck converters with the presented ZVS technique have higher efficiency than conventional ones, especially at higher frequencies. At about 3.6 MHz operation, the measured conversion efficiency of the PWM buck converter under DCM/CCM boundary mode with the proposed ZVS approach is 11% higher. [ABSTRACT FROM AUTHOR]

Driving power MOSFET at high switching frequency may induce significant switching power losses. A gate driver with low energy consumption is proposed for power MOSFET in switching power conversion applications. The proposed gate driver regulates the output gate driving voltage for minimizing the loss of charging and discharging the gate capacitor. No extra off-chip components are required, and hence, the proposed approach can be completely designed on chip. A 40 V10.5 μm CMOS technology is utilized and experiments on a boost converter are performed. The power dissipation of the proposed gate driver, compared with the conventional gate driver, can be reduced up to 15.5% and 55.4% under 15 V and 30 V supply voltage, respectively. [ABSTRACT FROM AUTHOR]

A zero-voltage-switching (ZVS) method utilizing high-order current harmonics for piezoelectric transformer (PT) backlight inverter is presented. In order to enhance the efficiency of PT backlight inverter, a large inductor is usually connected in series with PT for ZVS and filtering. Utilizing high-order current harmonics for ZVS can greatly reduce the required series inductance. The ZVS condition of the proposed approach is analyzed, and related experimental waveforms are shown. This method also minimizes the delay introduced into the inverter control loop, and makes the designs between ZVS and control loop independent. Measured power conversion efficiency of the tested PT backlight inverter is 85%. [ABSTRACT FROM AUTHOR]

A novel high-frequency driving scheme was proposed in this paper to improve the luminous efficiency of a plasma display. High-frequency oscillating waveform was applied to the address electrodes of the conventional three-electrodes ac-type plasma display panel during the sustaining period. More vacuum ultraviolet rays were generated by the high-frequency waveform so that the luminance and luminous efficiency could be enhanced. From experiments on an 8.5-in panel, the luminance was improved and the luminous efficiency was enhanced more than 40%. [ABSTRACT FROM AUTHOR]

The traditional frequency-shift methods for islanding detection of grid-connected PV inverters—the active frequency drift method and the slip-mode frequency-shift method—become ineffective under certain paralleled RLC loads. The automatic phase-shift method is proposed in this paper to alleviate this problem. The method is based on the phase shift of the sinusoidal inverter output current. When the utility malfunctions, the phase-shift algorithm keeps the frequency of the inverter terminal voltage deviating until the protection circuit is triggered. Simulation and experiments are performed for verification. [ABSTRACT FROM AUTHOR]

Presents a study which proposed a mixed-mode sustain method to improve the luminous efficiency of alternating current plasma display panels. Information on conventional surface-type sustain method and mixed-mode sustain method; Improvement of luminous efficiency; Effect of weaker surface sustain discharge.

In this paper, a novel sustaining driving waveform for ac-type plasma display panels is proposed. Significant improvement of the luminous efficiency can be achieved. The improvement comes from introducing self-erase discharges into the sustaining period. The self-erase discharge not only changes the sustaining discharge into a more efficient state, but also emits visible light additionally. Experimental verification under the same luminance 600 cd/m2 is performed on a 42-in plasma display panel. It is shown that the proposed sustaining driving approach consumes less power in the process of light emission by about 146 W than the conventional sustaining driving approach [ABSTRACT FROM PUBLISHER]