HVIC switch for high-frequency power converters

A high voltage integrated circuit (HVIC) switch designed as a building block for power converters operating up to 13.56 MHz from off-line voltages is presented. A CMOS-compatible, 500 V power device process is used to integrate control circuitry with a high-speed MOS gate driver and high voltage lateral power MOSFET. Fabrication of the HVIC switches has proceeded in two stages. The first batch of devices showed switching times of less than 5 ns for the power switch and good high frequency performance of a level-shifter for driving half bridge converters. In the second phase, a switch that monolithically integrates all the elements required to form a complete high-frequency converter has been designed.

Dead-time minimisation using active voltage control gate drive for high-power IGBT converters

High-power converters usually need longer dead-times than their lower-power counterparts and a lower switching frequency. Also due to the complicated assembly layout and severe variations in parasitics, in practice the conventional dead-time specific adjustment or compensation for high-power converters is less effective, and usually this process is time-consuming and bespoke. For general applications, minimising or eliminating dead-time in the gate drive technology is a desirable solution. With the growing acceptance of power electronics building blocks (PEBB) and intelligent power modules (IPM), gate drives with intelligent functions are in demand. Smart functions including dead time elimination/minimisation can improve modularity, flexibility and reliability. In this paper, a dead-time minimisation using Active Voltage Control (AVC) gate drive is presented. © 2012 IEEE.

Effect of urban climate on building integrated photovoltaics performance

It is generally recognized that BIPV (building integrated photovoltaics) has the potential to become a major source of renewable energy in the urban environment. The actual output of a PV module in the field is a function of orientation, total irradiance, spectral irradiance, wind speed, air temperature, soiling and various system-related losses. In urban areas, the attenuation of solar radiation due to air pollution is obvious, and the solar spectral content subsequently changes. The urban air temperature is higher than that in the surrounding countryside, and the wind speed in urban areas is usually less than that in rural areas. Three different models of PV power are used to investigate the effect of urban climate on PV performance. The results show that the dimming of solar radiation in the urban environment is the main reason for the decrease of PV module output using the climatic data of urban and rural sites in Mexico City for year 2003. The urban PV conversion efficiency is higher than that of the rural PV system because the PV module temperature in the urban areas is slightly lower than that in the rural areas in the case. The DC power output of PV seems to be underestimated if the spectral response of PV in the urban environment is not taken into account based on the urban hourly meteorological data of Sao Paulo for year 2004. © 2006 Elsevier Ltd. All rights reserved.

IGBT converters conducted EMI analysis by controlled multiple-slope switching waveform approximation

IGBTs realise high-performance power converters. Unfortunately, with fast switching of the IGBT-free wheel diode chopper cell, such circuits are intrinsic sources of high-level EMI. Therefore, costly EMI filters or shielding are normally needed on the load and supply side. In order to design these EMI suppression components, designers need to predict the EMI level with reasonable accuracy for a given structure and operating mode. Simplifying the transient IGBT switching current and voltage into a multiple slope switching waveform approximation offers a feasible way to estimate conducted EMI with some accuracy. This method is dependent on the availability of high-fidelity measurements. Also, that multiple slope approximation needs careful and time-costly IGBT parameters optimisation process to approach the real switching waveform. In this paper, Active Voltage Control Gate Drive(AVC GD) is employed to shape IGBT switching into several defined slopes. As a result, Conducted EMI prediction by multiple slope switching approximation could be more accurate, less costly but more friendly for implementation. © 2013 IEEE.

Shaping pulse transitions by active voltage control for reduced EMI generation

High-performance power switching devices (IGBT/MOSFET) realise high-performance power converters. Unfortunately, with a high switching speed of the IGBT or MOSFET freewheel diode chopper cell, the circuit has intrinsic sources of high-level EMI. Therefore, costly EMI filters or shielding are normally demanded on the load and supply side. Although an S-shaped voltage transient with a high order of derivation eliminates the discontinuity and could suppress HF spectrum of EMI emissions, a practical control scheme is still under development. In this paper, Active Voltage Control (AVC) is applied to successfully define IGBT switching dynamics with a smoothed Gaussian waveform so a reduced EMI can be achieved without extra EMI suppression devices. © 2013 IEEE.

Wave energy emulator and AC/DC rectifiers for direct drive wave energy converters

This paper describes a solid state electrical emulator devised for laboratory testing of power conditioning electronics for direct drive linear wave energy converters (DDLWEC). Two rectification strategies are considered; a uni-directional boost topology, and an H-bridge which may be controlled in either uni- or bidirectional modes.

Energy recovery from high-frequency clocks using DC-DC converters

Large digital chips use a significant amount of energy to distribute a multi-GHz clock. By discharging the clock network to ground every cycle, the energy stored in this large capacitor is wasted. Instead, the energy can be recovered using an on-chip DC-DC converter. This paper investigates the integration of two DC-DC converter topologies, boost and buck-boost, with a high-speed clock driver. The high operating frequency significantly shrinks the required size of the L and C components so they can be placed on-chip; typical converters place them off-chip. The clock driver and DC-DC converter are able to share the entire tapered buffer chain, including the widest drive transistors in the final stage. To achieve voltage regulation, the clock duty cycle must be modulated; implying only single-edge-triggered flops should be used. However, this minor drawback is eclipsed by the benefits: by recovering energy from the clock, the output power can actually exceed the additional power needed to operate the converter circuitry, resulting in an effective efficiency greater than 100%. Furthermore, the converter output can be used to operate additional power-saving features like low-voltage islands or body bias voltages. ©2008 IEEE.

A 660MHz ZVS DC-DC converter using gate-driver charge-recycling in 0.18μm CMOS with an integrated output filter

The design and manufacture of a prototype chip level power supply is described, with both simulated and experimental results. Of particular interest is the inclusion of a fully integrated on-chip LC filter. A high switching frequency of 660MHz and the design of a device drive circuit reduce losses by supply stacking, low-swing signaling and charge recycling. The paper demonstrates that a chip level converter operating at high frequency can be built and shows how this can be achieved, using zero voltage switching techniques similar to those commonly used in larger converters. Both simulations and experimental data from a fabricated circuit in 0.18μm CMOS are included. The circuit converts 2.2V to 0.75∼1.0V at ∼55mA. ©2008 IEEE.

A fully integrated 660 MHz low-swing energy-recycling DC-DC converter

A fully integrated 0.18 μm DC-DC buck converter using a low-swing "stacked driver" configuration is reported in this paper. A high switching frequency of 660 MHz reduces filter components to fit on chip, but this suffers from high switching losses. These losses are reduced using: 1) low-swing drivers; 2) supply stacking; and 3) introducing a charge transfer path to deliver excess charge from the positive metal-oxide semiconductor drive chain to the load, thereby recycling the charge. The working prototype circuit converts 2.2 to 0.75-1.0 V at 40-55 mA. Design and simulation of an improved circuit is also included that further improves the efficiency by enhancing the charge recycling path, providing automated zero voltage switching (ZVS) operation, and synchronizing the half-swing gating signals. © 2009 IEEE.

Energy recycling from multigigahertz clocks using fully integrated switching converters

Large digital chips use a significant amount of energy to broadcast a low-skew, multigigahertz clock to millions of latches located throughout the chip. Every clock cycle, the large aggregate capacitance of the clock network is charged from the supply and then discharged to ground. Instead of wasting this stored energy, it is possible to recycle the energy by controlling its delivery to another part of the chip using an on-chip dc-dc converter. The clock driver and switching converter circuits share many compatible characteristics that allow them to be merged into a single design and fully integrated on-chip. Our buck converter prototype, manufactured in 90-nm CMOS, provides a proof-of-concept that clock network energy can be recycled to other parts of the chip, thus lowering overall energy consumption. It also confirms that monolithic multigigahertz switching converters utilizing zero-voltage switching can be implemented in deep-submicrometer CMOS. With multigigahertz operation, fully integrated inductors and capacitors use a small amount of chip area with low losses. Combining the clock driver with the power converter can share the large MOSFET drivers necessary as well as being energy and space efficient. We present an analysis of the losses which we confirm by experimentally comparing the merged circuit with a conventional clock driver. © 2012 IEEE.