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This paper introduces a new resonant gate driver for both the top and bottom switches of a synchronous buck converter. A coupled inductor is used to reduce the size as well as to transfer energy between the top and bottom gate driving. A possible semi-conductor integration approach is proposed for this resonant gate driver based on a self-adaptive control method. Theoretical analysis, simulation and experimental results prove that the proposed driver can greatly reduce the gate driving loss and that it is well suited to high-frequency applications. Index Terms--Gate drive, high frequency, resonant gate drive.

Gate drive circuits for modern power electronic switches, such as MOSFET and insulated gate bipolar transistor (IGBT), often require electrical isolation. This paper describes the modeling and experimental results of some coreless printed circuit board (PCB)-based transformers that can be used for MOSFET and IGBT devices at high-frequency (500 kHz to 2 MHz) operation. PCB-based transformers do not require the manual winding procedure and thus simplify the manufacturing process of transformer-isolated gate drive circuits. With no core loss, coreless transformers are found to have favorable characteristics at high-frequency operations. This project demonstrates an important point that the size of the magnetic core can approach zero and become zero when the frequency is sufficiently high. Index Terms - Coreless PCB transformers, gate drive circuits, high-frequency magnetics.

Gate drive circuits for power MOSFET's and insulated gate bipolar transistors (IGBT's) often require electrical isolation. Coreless printed circuit board (PCB) transformers have been shown to have desirable characteristics from a few hundreds of hertz to a few megahertz and can be used for both power and signal transfer at low-power level. At low operating frequency, the magnetizing inductance has such low impedance that the driving power requirement could become excessive. This paper describes the use of a coreless PCB transformer for isolated gate drive circuits over a wide-frequency range. based on a resonance concept, the optimal operating condition that minimizes the power consumption of the gate drive circuits is developed and verified with experiments. The coreless PCB transformer demonstrated here confirms a fundamental concept that the size and volume of a magnetic core could approach zero and become zero if the operating frequency is sufficiently high. Coreless PCB transformers do not require the manual winding procedure and tires simplify the manufacturing process of transformer-isolated gate drive circuits and low-power converters. Their sizes can be much smaller than those of typical core-based pulse transformers. The electrical isolation of a PCB is much higher than that of an optocoupler. Index Terms - Coreless PCB transformers, gate drive circuits, high-frequency magnetics.

This paper describes the modeling and implementation of a coreless printed circuit board (PCB)-based transformer with 'multiple' secondary outputs. This new PCB transformer has been successfully applied in complementary gate drive circuits in a novel low-profile power converter with high-power density and a converter bridge. The PCB-based transformers do not require the manual winding procedure and thus simplify the manufacturing process of transformer-isolated gate drive circuits. The use of the multiple secondary outputs can in principle simplify the complementary gate drive circuits that are often required in many power electronics applications. Index Terms - Coreless PCB transformers, gate drives, magnetics.

A method is presented to monitor the state of a converter with an unlimited number of paralleled insulated gate bipolar transistor (IGBT)/diode modules with individual gate drives. The monitoring functions can be implemented without extra signal processing or load-side components. The method is based on the active gate-controlled current balancing (CB) principle. This principle is reviewed in the first part of this paper, and the necessary supplements to implement the monitoring functions are shown. In the second part, experimental measurements are shown. This new control method allows monitoring the state of a converter and balancing the losses and current sharing between paralleled power devices without the need to match the devices nor the gate drives. Thus, the overall reliability can be increased without increasing the costs. Since no matching of the devices is needed, the handling and logistic costs can be significantly reduced. IGBT/diode modules for standard paralleling are selected, and only modules of the same class can be paralleled without excessive derating. The presented method allows switching off one of the paralleled branches in the case of parameter degradation and to keep the converter operating at a lower power. Index Terms - Availability, current balancing, insulated gate bipolar transistor, monitoring, paralleling. power converter, power module, power semiconductor devices, power semiconductor switches.

MOSFET's and insulated gate bipolar transistor (IGBT) devices are increasingly used in electronic circuits due to both their easy driving and ability to handle high currents and voltages at high-switching frequencies. This paper deals with a new driver technique that allows optimization of the switching speed, reduction of the energy losses during the switching time, and limitation of the electromagnetic interference (EMI). First, an analysis of voltage- and current-switching waveforms of gate-insulated devices is performed. Then, a method of controlling voltage and current slopes independently is shown using the 'one-cycle' method or a suitable adaptive-driving technique based on a phase-locked loop (PLL) approach. These techniques were adopted in order to allow correct generation of the gate signals regardless of the operating conditions. Finally, practical results of the proposed driving circuit obtained using a single IGBT switch chopper are presented. Index Terms - Device-switching transients, driver circuit, insulated gate devices, Miller-effect detection.

This paper presents the reasons that make series operation of insulated gate bipolar transistors (IGBT's) attractive and challenging and reviews the methods that may be used. Then, a new approach, which uses the IGBT's gate-controlled active regime in place of large voltage-sharing snubbers, is proposed. Analytical and simulation techniques are used to study the performance and conditions for stability given. It is concluded that when making each IGBT voltage follow a reference input, with closed-loop voltage control, the IGBT's are able to share the transient turn-off voltage without turn-off snubbers. This technique may lead to more compact and efficient high-voltage-power modules. Index Terms - Active voltage control, gate drives, high-voltage switching, IGBT, series connection.

In recent years, power MOSFET devices are replacing the bipolar transistor. However, the power MOSFET is a fairly new device and current modeling techniques have not produced an accurate simulation of the gate to source. The method presented here generated a more accurate model of the transient behavior and gate to source characteristics of the power MOSFET. The results provide a better correlation between the MOSFET model and the actual device.

Experiments were conducted to study the high energy, high di/dt pulse-switching characteristics of SCR's with and without the amplifying gate. High di/dt, high-energy single-shot experiments were first done. Devices without the amplifying gate performed much better than the devices with the amplifying gate. A physical model is presented to describe the role of the amplifying gate in the turn-on process, thereby explaining the differences in the switching characteristics. The turn-on area for the failure of the devices was theoretically estimated and correlated with observations. This allowed calculation of the current density required for failure. Since the failure of these devices under high di/dt conditions was thermal in nature, a simulation using a finite-element method was performed to estimate the temperature rise in the devices. The results from this simulation showed that the temperature rise was significantly higher in the devices with the amplifying gate than in the devices without the amplifying gate. From these results, the safe operating frequencies for all the devices under high di/dt conditions was estimated. These estimates were confirmed by experimentally stressing the devices under high di/dt repetitive operation.

A new analytical insulated gate bipolar transistor (IGBT) model for improved on-state characteristics prediction is proposed. Two-dimensional (2-D) effects in the forward conduction of an IGBT are studied analytically. These effects significantly influence the on-state characteristics of the device and must be accounted for when IGBT modeling. Dynamic characteristics and temperature effects are included in the model. Both three-dimensional (3-D) numerical simulation and experimental results support the theoretical analysis. Index Terms - IGBT, model, on-state voltage, two-dimensional effects.