Zero-current Switching Technique Research Articles

Design and implementation of a novel zero‐current switching method for low‐power DC–DC converters

AbstractThis paper introduces a unique zero‐current switching (ZCS) technique for low‐power dc–dc converters. In this paper, a single‐inductor dual‐input triple‐output converter is considered to apply this new technique, which can be generalized for converters with more inputs and outputs and high‐power and energy‐harvesting applications. The first input of this converter can be connected to any source that can produce energy, such as photovoltaic (PV) cells or thermoelectric generator (TEG), and the second input can be considered a battery. The proposed converter is implemented discretely, and a low‐power microcontroller whose power consumption is reduced by the software is employed to control the whole system. In the proposed ZCS method, the current sensor is not used, and only a simple voltage level detector is employed to detect the inductor voltage level in order to determine the optimal value of the inductor discharge duty cycle. This converter works in discontinuous conduction mode (DCM) and uses pulse width modulation (PWM) and the time‐multiplexing strategy (TMS). The main focus of this paper is on designing and implementing a digital control algorithm based on this new ZCS technique in order to increase efficiency.

Single-Inductor, Multiple-Input, Multiple-Output, DC-DC Converter Based on a New Software Zero-Current Switching (ZCS) Technique

A single-inductor multiple-input multiple-output converter is proposed in this paper that can be used in low-power systems due to low output current and voltage. This converter is implemented discretely, and only one microcontroller is employed to control the system. The unique zero-current switching (ZCS) technique considered in this paper is such that only by reading the inductor’s left-side voltage the optimal value of the inductor discharge duty cycle is determined. This method can be generalized to low-power and high-power converters, whether implemented and designed as discrete or integrated. This converter works in discontinuous conduction mode. It uses pulse width modulation control and the time-multiplexing control method, which makes the system have high efficiency and makes the cross-regulation problem between the converter’s outputs tiny. The control algorithm considered in this converter is digital, which determines the optimal charge and discharge duty cycles. Also, the switching frequency of this converter is constant, relatively low, and equal to 5[Formula: see text]kHz. The efficiency of this converter has reached 91.6% by using the ZCS technique and other mentioned control methods.

Advanced Control Methods for Asymmetrical Half-Bridge Flyback

In this article, a power converter based on an asymmetrical half-bridge flyback topology is analyzed and optimized for small form factor and fast-charging power adaptors. Two resonant control methods, taking advantage of the forward and flyback characteristics of the converter, as well as the benefits of each of them depending of the operation point are discussed. The analysis is nourished with the equivalent circuits in each phase of operation and the equations that define them. Particularly innovative is the proposed zero voltage resonant valley switching control method for the mentioned converter; in this case, it is operated similarly to a flyback converter, allowing safe output voltage ramp up, which is one of the challenges that has limited the usage of this topology up to now. The manuscript also describes how to achieve high efficiency and power density using zero-voltage switching and zero-current switching techniques over the full range of the input voltage and the output load. Finally, the advantages of the proposed control methods are demonstrated in a 65-W adaptor prototype achieving a peak efficiency over 94.6% and an efficiency of 93.8% @ V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ac</sub> ≥ 100 V at full load over the range of the input voltage, as well as a world-class power density of 35 W/in <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> uncased.

Design and Implementation of an Auto-Oriented Bidirectional ZCS Hybrid Circuit Breaker

To protect power systems from severe short circuit faults, the zero-current switching (ZCS) technique is widely accepted due to its fast interruption speed. However, the traditional ZCS technique is more complicated in bidirectional switching, which limits its wide application, especially in AC power systems. Therefore, a novel auto-oriented bidirectional ZCS hybrid circuit breaker is proposed to simplify the overall topology of the circuit breaker. The design of the ZCS hybrid circuit breaker is based on the idea of diverting the pulse current toward the reverse direction of the fault current by the arcing voltage itself. The proposed scheme can interrupt bidirectional faults with just one ZCS circuit, without detecting fault current direction. Firstly in the paper, the topology and operating principles of the proposed bidirectional ZCS hybrid circuit breaker are introduced. Moreover, the key parameters are optimized to make the hybrid circuit breaker capable of bidirectional interruption automatically. Furthermore, dielectric recovery characteristics of the vacuum interrupter under special conditions are also measured to determine the design parameters. The proposed topology of the bidirectional ZCS hybrid circuit breaker is validated using a 450VAC/630A prototype. Short circuit breaking tests of the prototype are conducted without detecting fault current direction in advance. Experimental results show that the breaking time of the prototype is less than 1 ms in clearing either direction of fault current with a prospective value of 20 kA and $\text{d}i/\text{d}t$ of 8 A/ $\mu \text{s}$ . The feasibility of the proposed scheme is verified with these test results.

A Low-Stress Zero-Current Switching Technique for Power Converters

Huge voltage spikes on auxiliary switches is a common issue for most of the existing zero-current switching (ZCS) pulsewidth-modulated (PWM) converters. The reason for the spike lies in the parasitic resonance between the resonant inductance and the stray output capacitance C oss of the auxiliary switch, which does not have the negative impact in zero-voltage switching (ZVS) converters. This paper proposes a low-stress ZCS technique to eliminate the negative consequence of the C oss in ZCS PWM converters. All the power devices, including the auxiliary switch, show low voltage stresses and ZCS. The auxiliary cell of the low-stress ZCS technique introduced a clamping diode to realize the low-voltage stress for the power devices. The low-stress ZCS buck converter is taken as an example to explain both the low-stress and ZCS characteristics. A 2-kW hardware prototype is developed. The simulation and experiment results both validate the effectiveness of the proposed low-stress ZCS technique.

Zero-current switching technique for constant voltage constant frequency sinusoidal PWM inverter

In this paper, a new control strategy for zero-current transition technique is suggested to constant voltage constant frequency sinusoidal PWM inverter. This strategy consists of a resonant arm and auxiliary switches, which are connected to a standard single-phase full-bridge voltage source inverter and also to a proportional integral voltage controller. The main and auxiliary switches can be separately controlled. The suggested strategy is able to reduce switching losses successfully, and also it does not need any snubber circuit. By using appropriate switching algorithms, the strategy can be applied to uninterruptible power supplies, photovoltaic systems and DC/AC inverters as well. In this study, not only the theoretical analysis but the simulations of the suggested strategy have been carried out effectively. From the simulation results, it has been shown that the suggested strategy yields 30% less switching losses and has better performance when compared with the hard switching strategy for the same operating condition, including the conditions of the load and the switching frequency. Eventually, the suggested control scheme verified by the simulation results proves that it can achieve low THD values in addition to less switching losses.

A Family of Dual-Phase-Combined Zero-Current Switching Switched-Capacitor Converters

A family of dual-phase-combined resonant switched-capacitor (SC) converters with a similar structure is presented in this paper. Comparing with their conventional single-phase version, each of the proposed dual-phase converters is more than just a switched capacitor but also provides the service of two phases operated in the fully complementary manner. This design provides a more stable output voltage with low ripple and significantly reduces the quantity of switches. These converters therefore have the common features of smaller size, lower cost, and higher power density than the conventional multiphase SC converters. With the zero-current switching technique, the proposed converters also possess high-power conversion efficiency. The detailed analysis of the circuit operation and voltage ripples is presented. Experimental results are also provided to confirm the performance of the new family of converters.

A DC–DC Boost Converter With Variation-Tolerant MPPT Technique and Efficient ZCS Circuit for Thermoelectric Energy Harvesting Applications

This paper presents a dc-dc boost converter with the maximum power point tracking (MPPT) technique for thermoelectric energy harvesting applications. The technique realizes variation tolerance by adjusting the switching frequency of the converter. A finely controlled zero-current switching (ZCS) scheme together with the accurate MPPT technique enhances the overall efficiency of the converter because of an optimal turn-on time generated by a one-shot pulse generator that is proposed. Moreover, the ZCS technique can deal with low- and high-temperature differences applied to the thermoelectric generator. This allows a wider range of conversion ratios compared to those of conventional converters used for thermal energy harvesting. Experimentally, the converter implemented in a 0.35-μm BCDMOS process had a peak efficiency of 72% at the input voltage of 500 mV while supplying a 5.62-V output.

A Novel Control Technique for Soft-switching Sinusoidal Pulse Width Modulation Inverter

This article presents a new zero-current switching technique for a single-phase full-bridge sinusoidal pulse width modulation inverter. Two auxiliary switches and a resonant branch are attached to a conventional single-phase full-bridge inverter. The resonant branch can be controlled independently from the main power switches. This technique decreases turn-on and turn-off switching losses and does not require any snubber capacitor. The technique can be applied to DC/DC converters and DC/AC inverters with suitable switching algorithms. Both theoretical analysis and application of the proposed technique have been realized. It was seen that the proposed technique has 45% less switching losses and better performance than the hard-switching technique for the same load and switching frequency. The experimental results also approve the effectiveness of the zero-switching technique.

Combined ZVS–ZCS topology for high-current direct current hybrid switches: design aspects and first measurements

Power electronic switches have been considered for load switching ever since their invention. This is because semiconductor switches enable fast, arc-less, reliable and maintenance- free switching. The main disadvantages in relation to conventional switches (i.e. circuit breakers), however, are their sensitivity to transients, high on-state losses and the presence of leakage current. The advantages of both types of switches can be exploited by combining the semiconductor and the mechanical switch and thereby their disadvantages, arc formation and regular maintenance, can also be eliminated. For hybrid switches (HSs), both zero voltage switching (ZVS) and zero current switching (ZCS) are frequently used. A new hybrid switching topology has been developed where both ZVS and ZCS techniques are applied to the mechanical switch. The 'symbiosis' between these solid-state switching techniques and a mechanical switch eliminates several of the disadvantages, resulting in a more reliable direct current (DC) HS that requires less mainten- ance. The first turn-off measurement (up to 5 kA) from a prototype that has been developed for a 3-kV DC grid is presented.

A capacitor charging power supply utilizing a Ward converter

A prototype capacitor-charging power supply (CCPS) that utilizes a Ward converter is presented. This converter is a member of the family of resonant converters and is capable of zero-current switching. It is applicable to capacitor charging because of its inherent short-circuit protection and its insensitivity to the value of the load capacitance. The converter is controlled using a constant on-time constant frequency scheme that allows the utilization of zero-current switching techniques. The prototype CCPS is capable of charging various values of load capacitors up to 1000 V DC. Waveforms that show single- and repetitive-charge operation of the CCPS are presented. >

A capacitor-charging power supply using a series-resonant topology, constant on-time/variable frequency control, and zero-current switching

A power supply specifically designed for capacitor-charging applications that uses a series-resonant circuit topology, a constant on-time/variable frequency control scheme, and zero-current switching techniques has been developed. The performance of this capacitor-charging power supply (CCPS) has been evaluated in the laboratory by charging several values of load capacitance at various repetition rates. The CCPS has charged a 1 mu F capacitor from 0 to 1500 V DC in 750 mu s, exhibiting a charging power of 1500 J/s. This operation has been repeated at a rate of 800 charges per second, which corresponds to an average power output of 900 W. A 10 mu F capacitor has been charged from 0-1500 V DC in 8 ms. These results indicate that this design is feasible for use in capacitor-charging applications. >

Zero-voltage switching technique in DC/DC converters

A novel resonant switch operating under the principle of zero-voltage switching is presented. The basic configurations of the voltage-mode resonant switches are presented. The circuit's operating principles are described using a voltage-mode quasi-resonant boost converter. DC analysis of the converter is carried out. A new family of voltage-mode quasi-resonant converters are derived, and several members of this family are presented. The duality relationship between the zero-current switching technique and the zero-voltage switching technique is derived. These two techniques are compared using an example showing the duality between a current-mode quasi-resonant Buck converter and a voltage-mode quasi-resonant boost converter. The similarities and differences of the voltage-mode quasi-resonant converters and the Class-E converters are discussed. A 5 MHz 50 V to 5 V flyback converter employing the zero-voltage switching technique has been implemented. Design considerations and experimental results of this circuit are presented.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>