Zero-voltage Switching Condition Research Articles

Research on auxiliary resonant commutated pole inverter for driving brushless DC motor

The brushless DC motor is generally used in small satellite flywheel systems due to its good control performance and structure robustness. However, its driving inverter still suffers from hard-switching that leads to higher loss and larger heatsink requirement. The resulting low power density and EMI problems have been a great challenge for the space satellite applications. This paper describes a novel auxiliary resonant commutated pole inverter (ARCPI) for driving the brushless DC motor. An inserted inductor is controlled to resonant with the buffer capacitor of the inverter’s lower arm switches; a resonant capacitor is paralleled with the inductor branch as well. Zero-current switching and zero-voltage switching conditions are therefore realized for the switches of the entire circuit. The reverse recovery problem of diodes are also avoided by zero current turning-off. The working states of the proposed novel ARCPI inverter are analyzed and the mathematical model for every state is established. Furthermore, the parameter design is discussed to provide soft-switching conditions. Finally, the proposed ARCPI inverter is applied for driving a brushless DC motor. A voltage/current double closed control loop is designed for the motor controller and the system simulation setup is built. The simulation results prove that soft-switching operation is realized for all of the switches; the proposed inverter is effective for driving brushless DC motors. Besides, the motor current fluctuation decreases by 45.7%. The motor torque and the motor speed present with good control performance as well.

Coupled-Inductor-Based Dual Active Bridge Converter With Soft Switching Capability and Low Component Count

A coupled-inductor-based dual active bridge (DAB) converter with soft switching capability and low component count is proposed in this article. Under wide-input voltage range application, it only utilizes four active switches to achieve voltage regulation and can behave like the current-fed DAB (CF-DAB) converter. In addition, three magnetic components, including the input dc inductor, the transformer, and the leakage inductor, can all be integrated into one coupled inductor, thus reducing the magnetic component count. With the coupled-inductor structure, the voltage of the half bridge capacitor at the output side can be automatically changed according to different duty cycle. Consequently, the voltage matching at the two ports of the equivalent leakage inductor will always be satisfied by controlling the input capacitor voltage with the adopted pulsewidth modulation (PWM). Based on the detailed analysis of the working modes, power transfer characteristics, and zero-voltage switching (ZVS) conditions, full load range ZVS can be mathematically obtained, which shows that the full load range ZVS capability is an intrinsic feature of the proposed converter and is not related to the converter inductance values. Furthermore, the magnetic integration and parameter design are analyzed in detail. Finally, experimental results are provided to demonstrate the effectiveness of the proposed solution.

Analysis and implementation of an isolated high step‐down converter with interleaved output for low voltage applications

AbstractThis paper proposes a new isolated high step‐down dc‐dc converter with a more extensive output range and high efficiency. The interleaved output and ZVS‐ZCS switching for all semiconductors have made the converter appropriate for high output current applications. An auxiliary inductor is used to achieve the ZVS (zero‐voltage switching) and ZVZCS (zero‐voltage zero‐current switching) condition, which charges and discharges the parallel snubber capacitors of the power switches at different modes of operation. Therefore, the switching losses of semiconductor components are reduced significantly, which results in enhanced efficiency. Moreover, the connection of an auxiliary capacitor in series with the transformer has prevented the probability of DC‐current saturation. The proposed converter could be controlled with duty‐cycle or switching frequency variations. However, the output voltage control with the switching frequency variations gives an extended range of output voltage compared with the other presented converters. Moreover, a coupled inductor is used to relate the output gain with the turn ratios, which causes a more extensive range for output voltage gain. Finally, the theoretical analysis is given and is compared with a 140 W experimental prototype, which converts a higher input voltage 300v to 7.5 V of the output voltage.

Analysis and Design of Single-Ended Resonant Converter for Wireless Power Transfer Systems.

Single-ended resonant converters such as Class-E inverters have been widely considered as a potential topology for small- and medium-power wireless power transfer (WPT) applications, which feature compact circuits, low switching losses, and cost benefits, as they only use a low-side switch with a simple gate driver. However, there remains a practical challenge in the design of voltage stress, efficiency, and power density. In this paper, a single-ended resonant converter with a primary parallel resonant-matching network is investigated to absorb the bulky input-choke inductors of the Class-E inverters into the coil inductance. The analytical expressions for all the converter parameters are derived based on time-domain resonant waveforms, including: (1) analysis of critical zero-voltage switching (ZVS) conditions and (2) power transfer capabilities under the given maximum switch voltage stress. Furthermore, this paper elaborates on the design methodology of the proposed single-ended resonant converters, and an optimal operating point is chosen to ensure soft-switching operation and rated power. Finally, the accuracy of the proposed model is verified by simulation and experimental results.

Three Winding Coupled Inductor-Based Dual Active Bridge DC-DC Converter With Full Load Range ZVS Under Wide Voltage Range

In this article, a three winding coupled inductor-based dual active bridge (TWCI DAB) dc-dc converter is proposed. Similar to the current-fed DAB converter, the proposed TWCI DAB has small input current ripple and wide input voltage range. In addition, the zero-voltage switching (ZVS) of all switches in the full load range under wide input voltage variation can be realized. With the magnetic integration structure, the size of the total magnetics can be reduced, and the efficiency is also increased compared with the discrete magnetic case. To better analyze the working principle of the three winding coupled inductor, a general analysis method based on magnetic reluctance model is first introduced to obtain the expressions of high frequency current. Furthermore, ZVS analysis and inductor design to obtain low inductor root mean square (rms) current and full load range ZVS based on the ZVS conditions, maximum power transfer and rms current are presented. Finally, the validity of the proposed topology and design are verified by experimental results from a 1-kW laboratory prototype.

A Single-Stage Boost-Derived T-Type Inverter With Self-Balanced Capacitor Voltage

This article proposes a novel single-stage three-level buck–boost inverter based on voltage multiplier cells. The characteristics of the proposed topology are listed as 1) providing buck–boost operation in a single-stage power conversion, 2) reducing the number of components, 3) low component rating, and 4) automatic capacitor voltage balance without requiring any voltage sensors. A space-vector modulation (SVM) technique is introduced to control the proposed inverter and improve the quality of the output voltage waveform. In the SVM scheme, three nearest vectors are used to generate the output voltage vector in any switching period. The upper shoot-through switching state is adopted to provide buck–boost operations. This state is added within the small N-type vectors. The operating states, steady-state analysis, component selections, and comparison analysis are detailed. A 1-kVA laboratory prototype is built to validate the effectiveness of the proposed inverter. The experimental results show that the switch operates under a zero-voltage switching conditions for both turning- <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">on</small> and - <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">off</small> . Moreover, the capacitor voltage self-balanced characteristic keeps the voltage difference within 3.8% of the average capacitor voltage.

ZVS Analysis and Design for Half Bridge Bidirectional LLC-DCX Converter With Consideration of Nonlinear Capacitance and Different Load Under Synchronous Turn-On and Turn-Off Modulation

In the application of bidirectional LLC -DCX converter, synchronous turn-on and turn-off modulation can be adopted to simplify the control. In view of zero-voltage switching (ZVS) performance, conventionally, the magnetizing inductance is regarded as a current source to discharge output capacitance of primary switches, neglecting the effect of secondary output capacitance and load, which leads to insufficient accuracy and non-ZVS. This article presents the ZVS analysis and design for half-bridge LLC -DCX converter with consideration of nonlinear capacitance and different load values under the synchronous turn-on and turn-off modulation. With consideration of nonlinear capacitance and different load values, the charging and discharging process of the output capacitance during the dead time is analyzed in detail. The analysis indicates that the ZVS conditions are not only affected by the dead time and magnetizing inductance as in the previous study but also related to the load and other parameters. Based on in-depth analysis, more precise ZVS conditions on the magnetizing inductance, dead time, load, and resonant parameters are revealed. In addition, based on the obtained ZVS conditions, the guidance for parameters design is given to achieve full-load-range ZVS. Finally, the effectiveness of the proposed solution has been verified through experimental results.

Even-Harmonic Class-E CMOS Oscillator

This article proposes the theory and implementation of an even-harmonic class-<inline-formula> <tex-math notation="LaTeX">$E$ </tex-math></inline-formula> CMOS oscillator that displays an excellent phase noise performance. Starting from zero voltage switching (ZVS) and zero derivative switching (ZDS) conditions, expressions for drain voltage and current waveforms are derived. Based on a 1:1 transformer, a custom-designed tank is proposed, which satisfies ZVS and ZDS conditions for the core transistors, provides high-<inline-formula> <tex-math notation="LaTeX">$Q$ </tex-math></inline-formula> resonances at both fundamental and second harmonics of the oscillation frequency, and yields a passive voltage gain from the drain to the gate of the core transistors. Satisfying ZVS and ZDS conditions reduces the overlap between the voltage and current waveforms of the transistor that increases the power efficiency of the oscillator. Furthermore, it widens the flat span of the semi half-sinusoidal voltage waveform, where the impulse sensitivity function (ISF) is negligible. Therefore, the conversion of the core transistor noise to phase noise is reduced. These features improve the oscillator&#x2019;s figure of merit (FoM) in comparison with state-of-the-art CMOS oscillators. The prototype of the even-harmonic class-<inline-formula> <tex-math notation="LaTeX">$E$ </tex-math></inline-formula> oscillator is implemented in a 0.18-<inline-formula> <tex-math notation="LaTeX">$\mu \text{m}$ </tex-math></inline-formula> CMOS technology. At 4 GHz, it exhibits a phase noise of &#x2212;152.75 dBc/Hz at a 10-MHz offset while providing a 10.6% tuning range. The corresponding FoM is 197.9 dBc/Hz. The circuit draws 7 mA from a 0.7-V supply, and the die area is 0.23 mm².

Phase-Shifted Full-Bridge ZVS DC-DC Converter with Synchronous Double Rectifiers for Battery Charging Applications

This paper presents a phase-shifted PWM-controlled DC to DC power converter with a synchronous double rectifier. The power switches can be directed to achieve the zero-voltage switching condition using the technology of the full-bridge power converter and increase the efficiency of the converter on the secondary side of the transformer. A current doubling rectifier with low current ripple and synchronized rectifier circuits are also adopted. The secondary side of the high-frequency transformer uses the synchronous double rectifier. The synchronous double rectifier circuit converts AC voltage to DC voltage to enable high-current applications with two filtering inductors to reduce losses and dissipate heat, resulting in an efficient system. The proposed method can control the input DC voltage of the phase-shifted power converter at 400 V and achieves the required DC voltage of 24 V for battery charging applications under the zero-voltage switching condition. The results of simulations and experiments show 86.7% efficiency at 40% load condition and 91.8% efficiency at full load condition.

A Magnetic Integrated Method Suppressing Power Fluctuation for EV Dynamic Wireless Charging System

This article proposes a magnetic integrated method for the coupler of the electric vehicle dynamic wireless charging system to suppress power fluctuation by transforming the problem into designing a stable equivalent mutual inductance between the receiving coil and transmitting coils on the road. Both primary-side and secondary-side couplers adopt a magnetic integrated design. The primary-side coupler integrates a reverse coil inside the transmitting coil, and the secondary-side coupler integrates a coil in the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LCC</i> resonance compensation inside the receiving coil. Two advantages are unveiled through theoretical analysis of system characteristics: the original single mutual inductance is replaced by the mutual inductance difference between the two reverse series transmitting coils and the receiving coil to determine the power transmission, which suppresses output power fluctuation; the secondary-side integrated inductor coil replaces the external bulky compensation inductor in the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LCC</i> resonance compensation network and additionally realizes better zero-voltage switching conditions. The optimized design process considering the additional couplings is given based on circuit analysis. A prototype is implemented to validate the proposed design. Experimental results show that the output power fluctuation is within ±4% during dynamic charging at a power level of 4.5 kW, and the efficiency reaches 91.6%.

An Optimal Structure for High Step-Up Nonisolated DC–DC Converters With Soft-Switching Capability and Zero Input Current Ripple

In this article, an optimal structure for a high step-up nonisolated dc–dc converter is proposed. In this topology, the required high voltage gain can be obtained with a low number of elements. Furthermore, by implementing an auxiliary circuit, zero-voltage switching condition for the switches is provided, input current ripple has been reduced to almost zero, and all of the power diodes turn <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">off</small> and <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">on</small> under zero-current conditions. In the proposed structure, to regulate voltage gain, the extendable number of diode–capacitor voltage multiplier (DCVM) stages are combined with a coupled inductor. The voltage stresses across the semiconductors can be regulated by the number of the DCVM stages and the turns ratio of the coupled inductor. Thus, it provides two degrees of freedom for the designer to use low-rated semiconductors, which increases the converter efficiency. In this article, the performance of the proposed converter, in terms of voltage stress, voltage gain, and efficiency, has been analyzed, and a comprehensive comparison between the presented topology and other similar topologies presented. Finally, to verify the performance of the proposed topology, a 500 W (40 V/400 V) laboratory prototype has been developed and tested. The experimental results confirm its superiority and suitability.

Single-Phase ZVS Quasi-Z-Source Inverter With High Voltage Gain

A single-phase zero-voltage switching (ZVS) quasi-Z-source inverter with a high voltage gain is proposed, and important conclusions are obtained through the in-depth analysis of the key technologies, such as the topology, control strategy, high-frequency switching process, voltage transfer ratio, resonant processes, and ZVS condition, and the design criteria of key parameters. The inverter is composed of an impedance network with a high voltage gain, a ZVS auxiliary network, a single-phase inverter bridge, and an output <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LC</i> filter, adopting the unipolar SPWM control strategy with instantaneous feedback of output voltage and energy storage capacitor voltage. The impedance network is comprised of an energy storage inductor and two same diode–inductor–capacitor–capacitor cells; the ZVS auxiliary network includes a resonant inductor, a clamping capacitor, and an auxiliary switch, which provides the ZVS condition for power switches. The experimental results of a 1-kVA prototype verify that the proposed inverter features a high voltage gain, ZVS of all switches, high conversion efficiency, high output power quality, and strong load adaptability and has an important prospect in single-phase inversion with low input voltage or wide input voltage range.

Step-Up and Step-Down Converter Integrated With Motor Inverter for Powertrain Applications

Motor inverter high-voltage regulation improves the system efficiency and reduces the dimensions of a permanent magnet synchronous motor (PMSM). This article presents an isolated inverter with step-up and step-down dc-link voltage regulation for an electrical vehicle powertrain system, which will improve the system performance in wide ranges of load and battery levels. Step-up and step-down converter and the motor inverter are merged into a single converter. Bidirectional and galvanically isolated energy transmission between battery and motor with reduced semiconductors number, easy control, and high efficiency are demonstrated. In addition, inverter transistors’ RMS current results lower than in common solutions. Topology waveforms, devices losses, and zero-voltage switching (ZVS) condition are analyzed. Based on this study, a converter design procedure to meet main electrical vehicles requirements is proposed. Converter operation and design procedure are verified by simulation and experiment in two prototypes of 3.3 kW and 300 W.

Hybrid SPS Control for ISOP Dual-Active-Bridge Converter Based on Modulated Coupled Inductor With Full Load Range ZVS and RMS Current Optimization in DC Transformer Applications

The Input-serial-output-parallel (ISOP) dual-active-bridge (DAB) converter is an attractive solution to be used as a DC transformer (DCT) in the DC power distribution system. However, due to zero-voltage-switching (ZVS) limitation and large circulating current, the efficiency of the converter will be reduced. To improve the efficiency, an ISOP DAB converter based on a modulated coupled inductor, and a corresponding hybrid SPS control are proposed in this paper. With the hybrid SPS control strategy, the equivalent leakage inductance of modulated coupled inductor can be controllable. The large inductance is adopted at light load and the small inductance for the transformer is applied at heavy load to reduce circulating current and extend the ZVS range. By optimizing the root-mean-square (RMS) current of two operation modes of the converter, a control boundary of the hybrid SPS control can be obtained to modulate the coupled inductor. Meanwhile, the additional magnetizing inductance is utilized to achieve ZVS for all switches. The analysis based on the RMS current optimization and ZVS condition is given. Based on the conditions of the full load range ZVS and small RMS current, the parameters of the modulated coupled inductor, the turn ratio of the transformer, and magnetizing inductance are designed. Finally, a 250kHz, 800/400V, 2000W ISOP DAB prototype is built to verify the effectiveness of the proposed method. Meanwhile, a comparison experiment with the conventional individual leakage inductors solution is given, which shows performance improvements of the proposed solution.

A Fixed Frequency Zero-Voltage-Switching On-Board EV Charger

For electric vehicle (EV) onboard charging, high efficiency and power density of the charger is required. Soft switching technique is an effective way to increase On-Board Charger (OBC) power density and efficiency. This paper presents a fixed frequency zero-voltage-switching OBC topology which can realize Zero-Voltage-Switching (ZVS) of all the power semiconductor devices. An auxiliary resonant branch is used to realize Zero-Voltage-Switching for both front-end full-bridge rectifier and phase-shift full-bridge dc-dc converter. A novel PWM scheme is proposed for the OBC topology. ZVS conditions are derived. Finally, the proposed OBC is verified by the experiment.

A Hybrid Switching Modulation of Isolated Bidirectional DC-DC Converter for Energy Storage System in DC Microgrid

Isolated bi-direction DC-DC converters are widely used for energy storage systems (ESS) of DC microgrids. Particularly, a current-fed isolated bi-directional DC-DC converter (CF-IBDC) receives much attention due to its merits such as the naturally attenuated current ripple on the battery side. However, high efficiency cannot be obtained at the light and heavy load conditions under the conventional control methods. In this paper, a hybrid switching modulation is proposed to improve the power conversion efficiency of the CF-IBDC under light and heavy load conditions. The duty cycle of the secondary sides and the phase shift angle are independently controlled according to the amount of the transferred power. The control strategy is based on the optimization of zero-voltage switching (ZVS) conditions and the minimization of the circulating current in the power converter. Using the proposed control algorithm, the ZVS capability can be obtained under the entire load condition, and the circulating current can be minimized under the single phase-shift modulation (SPSM). Experimental results with a 1-kW laboratory prototype CF-IBDC validate the effectiveness of the proposed modulation algorithm.

A High-Efficiency ASK-Modulated Class-E Power and Data Transmitter for Medical Implants

In this article, we propose an amplitude-shift keying (ASK) modulation technique for Class-E power transmitters used in the inductive power and data transfer links. The proposed modulation circuit consists of a capacitor and a transistor, which switch the load network of the Class-E transmitter between two states; in one state, the drain waveform of the Class-E transistor satisfies both zero-voltage switching (ZVS) and zero-voltage-derivative switching conditions, while in the other one, the waveform approximately satisfies the ZVS condition. Therefore, at both states, the dc-to-ac power conversion efficiency is high, but the transmitted power is different, which allows the implementation of ASK data modulation in the transmitter. We also present an analytical procedure to design the circuit for the desired output power and data modulation index (MI). We have verified the design procedure in both simulation and measurement. The implemented inductive link consists of a 2.4- <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\mu$</tex-math></inline-formula> H transmitter coil and a 1.1- <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\mu$</tex-math></inline-formula> H receiver coil, separated by a 10-mm air gap. With a carrier frequency of 10 MHz, the power transfer efficiency and the power delivered to load were measured to be 64.6% and 35 mW, respectively. With MI = 10%, the bit error rate for the data rates of 1 and 2 Mb/s was measured to be less than 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">–8</sup> and 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">–6</sup> , respectively.

Design Considerations for PPS Controlled Current-Fed DAB Converter to Achieve Full Load Range ZVS and Low Inductor Current Stress

Current-fed dual active bridge dc–dc converters are suited for renewable energy systems such as solar photovoltaic and fuel cells, due to the advantages of small input current ripple and wide input voltage range. In this article, a current-fed dual active bridge dc–dc converter based on pulse width modulation plus phase shift control is studied. The working principle and zero-voltage switching (ZVS) conditions of the converter are analyzed in depth, and it is proved mathematically for the first time that all switches can naturally achieve ZVS independently of dc inductance and leakage inductance under a wide input voltage range within full load range. Based on maximum power transfer, peak current, and root mean square (RMS) current analysis, optimal dc inductance and leakage inductance design to obtain low inductor RMS current is proposed. In addition, the detailed loss breakdown was implemented by comparing it with the nonoptimized case. The effectiveness of the theoretical analysis and design method has been verified by experimental results.

A Contactless Receptacle Applied to DC Power Distribution

The modern household power distribution with dc-to-dc power transfer is presented in this paper in order to demonstrate inductive power transfer technology over air-core and ferromagnetic-core. A high-frequency switching with a five-level diode clamped multilevel converter plays an important role in generating a low-%THD voltage waveform in order to increase the power density or reduce the size of the plug and receptacle. The major setbacks of using the dc-to-dc power transfer with electric shock, galvanic isolation issue and arc discharge on the contactor have been solved by using the inductive power transfer. In addition, an LLC series resonant tank is integrated with the power converter to satisfy the Zero-Voltage Switching (ZVS) condition of all active switching devices. The proposed contactless receptacle technique is validated by using MATLAB/Simulink and a developed hardware prototype. The efficiency of the power transfer while using the magnetic material core versus the air-core type is approximately 83.8% and 92.6%, respectively.

Soft Switched Flyback Converter Using Active Lossless Snubber

In this paper, a new active lossless snubber circuit is proposed which provides soft switching condition for the traditional pulse width modulation (PWM) fly-back converter. This active lossless snubber circuit creates Zero Voltage Switching (ZVS) condition for the main switch, while Zero Current Switching (ZCS) condition is achieved for the auxiliary switch. Moreover, based on soft-switching condition, diode reverse recovery problem is omitted that leads to reduction of switching losses and increased efficiency. Also, the voltage stress of the auxiliary switch is clamped to the input voltage level which leads to its low capacitive turn ON loss. Furthermore, the presented active lossless snubber circuit provides soft-switching condition independent of load condition. The main and auxiliary switches do not need isolated gate driver, since their source pins are connected to the input ground. In this manuscript, the different operating modes are explained in details and also, a comprehensive design procedure is presented. Furthermore, loss breakdown for converter elements is offered at full load. The simulation results of the proposed converter using PSPICE software are shown for 155V input, 24 V, 120 W output and 100 kHz switching frequency to justify the theoretical analysis. The proposed converter has a high efficiency of 94.08% at full load.