Dead-time effect is one of the dominant sources of output current and voltage distortion for pulse width modulated (PWM) amplifiers. Practical switching devices have finite turnon and turn-off time. To avoid short circuit a blanking time is added between turn-off and turn-on of the complementary working switches in a switching-leg. The blanking time, also referred to as dead-time, results in a nonlinear voltage error of the PWM output stage. Especially high-precision applications that require accurate input current for positioning systems suffer from the dead-time effect. Extensive studies have been done on the analysis and elimination, minimization and compensation of dead-time in PWM converters. Most of these techniques rely on the detection of the polarity of the output current of the converter. By using only the polarity of the output current, the inductor current ripple is neglected, which is not sufficient for high-precision applications. In this paper nonlinear feedforward of the current setpoint is used to compensate the dead-time effect. This simple feedforward technique leads to significant improvement of the current tracking during zero crossings over a high output current frequency range, as demonstrated by measurement results.

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In existing half/full-bridge high-precision amplifiers, output distortion is present due to the required switch blanking time. The OCC topology does not require this blanking time but has a much higher total inductor volume compared to the half bridge. In this paper, a patented new topology is introduced that has the advantages of the OCC but with a much lower total inductor volume. The basic operation and properties of the ELOCC topology are explained including an extended optimization of the total inductor volume and an average model for control design. A prototype ELOCC current amplifier has been developed. The behavior of this prototype is in good agreement with the obtained simulation results. Even though the prototype is not fully optimized, the linearity compared to a full bridge is already impressive.Index Terms-DBI, dual-buck inverter, ELOCC, high precision, OCC, opposed current converter.

Practical switching devices have finite turnon and turn-off times. To avoid short circuit, a blanking time is added between turn-off and turn-on of the complementary working switches in a switching-leg. The blanking time, also referred to as dead-time, is one of the dominant sources of output current and voltage distortion in pulsewidth modulated power amplifiers. Extensive studies exist on elimination, minimization, and compensation of the effect. Most techniques achieve a reduction of the distortion but are not capable of completely removing it. The dual-buck converter does not suffer from blanking-time-related distortion. However, blanking time is not the only source of switching-leg-induced distortion. This paper focuses on the effects of semiconductor device parameters on the output quality of the dual-buck converter. It is shown that, ideally, the forward voltages of the diodes and switches have no effect on the output quality. Measurements on a prototype, industrial power stack based, dual-buck converter show a 100 times improvement of the open-loop spurious free dynamic range when compared to conventional pulse width modulated converters.

Switch blanking time, also referred to as dead-time, is one of the dominant sources of output current and voltage distortion in pulse width modulated amplifiers. Extensive studies are known on elimination, minimization, and compensation of the effect. Most techniques achieve a reduction but are not capable of completely removing it. This paper demonstrates that it is possible to fully eliminate dead-time effects by applying the socalled opposed current converter topology in combination with advanced feedforward techniques. The zero-crossing behavior of the opposed current converter is analyzed and compared to a conventional full-bridge converter with equivalently filtered output. Simulations and measurements on a full-bridge and an opposed current converter of 1.5 kW are included to demonstrate the effectiveness of the proposed ideas for high-precision applications.

Abstract-A robust self-interleaving mechanism for parallel hysteresis current controlled inverters is proposed, with sustained switching under all load conditions. A fast interleaving technique that can be applied for normal load conditions is combined with a self-interleaving mechanism, which ensures correct switching during voltage clamping operation. A minimum switching frequency and maximum duty cycle is guaranteed under all load conditions enabling the use of low-cost bootstrap circuits to drive the highside switches. The interleaving approach results in reduced volume of the passive components and better dynamic response. The self-interleaving mechanism was analyzed using the state-plane method, extended to multiple parallel modules. Simulations were conducted to verify the combined operation of both methods and measurements were performed on a 3 kW prototype zero-voltage-switching inverter with a discrete hysteresis current controller.

The opposed current converter (OCC) is a highprecision power amplifier that does not require blanking time in between switching and hence has high output quality. Like most of industrial power amplifiers, OCCs are typically controlled by classical control methods, which are simple and able to guarantee certain local optimality. However, physical constraints of the system are often neglected in the classical control design, which might lead to unreliable operation. More advanced control methods that can handle constraints are often of high complexity. This paper proposes an explicit control design method for the OCC based on a sequence of quadratic control contractive sets. The proposed controller can be computed by a single linear matrix inequality. It is proven to guarantee stability, locally optimal performance, constraints satisfaction and it has low complexity. Experimental results on a prototype OCC demonstrate the effectiveness of the proposed method.

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