Capacitive Hybrid Research Articles

Simultaneous Wireless Power and Data Transfer: A Comprehensive Review

Simultaneous wireless power and data transfer (SWPDT) is widely investigated because of the increasing requirement for real-time communication between the primary and secondary sides in wireless power transfer systems. This article classifies SWPDT systems into four categories according to the type and number of data channels and data carrier generation method. They are power carrier-based SWPDT system, high-frequency data carrier-based SWPDT system, multiple inductive channels SWPDT system, and inductive–capacitive hybrid channels SWPDT system, respectively. Four key issues, including cross-talk minimization, improvement of signal-to-noise ratio, modulation method for high data rate and low bit error rate, and special design to achieve full-duplex communication and improve misalignment tolerance, are discussed. The advantages, disadvantages, and applications of the four types of SWPDT systems are summarized. Finally, conclusions and outlook of the SWPDT system are given.

Analysis and Design of Inductive and Capacitive Hybrid Wireless Power Transfer System for Railway Application

Inductive power transfer (IPT) and capacitive power transfer (CPT) are mainly two effective ways to achieve wireless power transfer (WPT). IPT system needs capacitor to compensate the system, while the CPT system requires inductor to tune the system. Therefore, IPT coupler can be used to compensate the CPT coupler and vice versa. In this article, an inductive and capacitive hybrid wireless power transfer (HWPT) system is proposed to improve the system coupler antimisalignment ability. The couplers of IPT and CPT are employed together to compensate each other and transfer power together. Superposition theory is used to analyze the system working principle in detail. With the analysis results, a scaled-down system is built to validate the performance of the proposed approach. Experimental results show that the proposed HWPT system can achieve 653 W output power with 87.7% dc–dc efficiency at the well-aligned condition, and the maximum variation of the output power is 8.3% with the coupler misalignment from 0 to 270 mm (halfwidth of the coupler), which agree well with the analysis results.

A 169.6-GHz Low Phase Noise and Wideband Hybrid Mode-Switching Push–Push Oscillator

A wideband hybrid mode-switching push-push oscillator with low phase noise is presented in this paper. To achieve the wide tuning range, the inductive and capacitive hybrid mode-switching technique is proposed for the first time. It introduces more freedom of design parameters (i.e., inductance and capacitance) in the resonant tank. Under certain tuning range requirement, the hybrid mode-switching oscillator achieves higher input impedance of the resonator compared to the conventional mode-switching oscillators. Meanwhile, a transformercoupled inductor ring with symmetrical layout configuration is proposed to realize the switch-less hybrid mode switching, which further improves the circuit performance at sub-THz. Therefore, a good phase noise performance can be obtained within a wide tuning range, which leads to a relaxed tradeoff between the phase noise and tuning range. To verify the aforementioned mechanism operating at sub-THz band, a hybrid mode-switching oscillator based on the dual-mode push-push topology is proposed and fabricated in a conventional 28-nm CMOS technology. The measured results show a 21.7% tuning range with the center frequency of 169.6 GHz and a state-of-the-art FoM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">T</sub> of -180.6 dBc/Hz. The core circuit only occupies 0.039 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> , while drawing 95 mW with a 0.9-V supply.

A Novel Soft Switching Bidirectional DC–DC Converter Using Magnetic and Capacitive Hybrid Power Transfer

This paper proposes a new bidirectional dc-dc converter capable of improving the convenience and modularity of the dc power grid system. By the unique operation of the $LC$ resonant transformer, the proposed converter achieves bidirectional power control with only two switches. Also, the resonant transformer drives the soft switching turn-on and turn-off over a wide power range. Hence, the circuit has high potential to downsize the converter by exploiting high frequency and simplicity. This paper provides the operating principle and the experimental verification of the proposed circuit. A prototype was fabricated by using a simple and high-density printed circuit board ($\geq$ 10 W/cc). It is verified that the circuit resonant operation successfully drives bidirectional power control with high efficiency ($\geq$92%). An application example is also provided for dc grid system integration.

Simulation and experimental investigation of a high-Temperature superconducting inductive pulsed power supply with time delay effect of the secondary side

In this paper, to obtain a higher amplitude, higher energy transfer efficiency and better waveform quality of pulse current, a pulsed power supply that has time delay effect of the secondary side and the structure of inductive and capacitive hybrid energy storage is presented. The discharge circuit of power supply is improved and its principles and working processes are firstly analyzed. Besides, simulations and experiments are conducted for verification of the principles. It is found that, under the same experimental conditions, when delay time is 1 ms, the amplitude of pulse current is increased from 2769A to 3185A; and the energy transfer efficiency from the primary to secondary side is improved from 57.75% to 58.2%; the quality of pulse waveform is improved clearly compared with that of traditional discharge circuit. The aforementioned three aspects are compared comprehensively, which proves the feasibility and advantages of the improved discharge circuit. In Addition, the analysis of experimental results reveals the controllability of the proposed pulsed power supply, with which the continuous variation of the amplitude of pulsed current within limits can be realized.

The Meat Grinder With SECT Circuit

The meat grinder is a basic circuit for inductive pulsed-power supply (IPPS). Based on meat grinder, the Institute of Advanced Technology proposed a circuit called the slow transfer of energy through capacitive hybrid (STRETCH) meat grinder, in which an Integrated Gate Commutated Thyristors (IGCT) is selected as the main switch. Tsinghua University proposed the STRETCH meat grinder with inverse current commutation with semiconductor devices (ICCOS) in which the main switch is replaced by a thyristor and the ICCOS subcircuit is introduced to turn off the main switch. To reduce the opening switch voltage and increase the current turning-off capacity for IPPS, this paper presents a novel circuit topology named the meat grinder with self-charged capacitor and thyristors (SECTs). The key idea of the SECT topology is to turn off the primary current by the energy transfer capacitor, which is precharged. The meat grinder with SECT has larger capacity than the STRETCH meat grinder because it replaces the IGCT with a thyristor and is simpler than the STRETCH meat grinder with ICCOS because it only needs one capacitor. The suggested circuit is more suitable for IPPS module with high energy density. Simulation and experiment have been carried out to validate the circuit.

Review of the Meat Grinder Circuits for Railguns

With inherent strengths in energy density and power density, the inductive pulsed power supplies (IPPS) have become an attractive option for the power supplies in electromagnetic launch systems. The meat grinder circuits, including the slow transfer of energy through capacitive hybrid (STRETCH) meat grinder circuit, the STRETCH meat grinder with inverse current commutation with semiconductor devices circuit, and the meat grinder with self-charged capacitor and thyristors circuit, constitute one major branch among the IPPS circuits. This paper summarizes the fundamental research work and contributions of the meat grinder circuits from the perspectives of circuit improvements, performance analysis, inductor design, module collaboration, and efficiency promotion. The future directions of single IPPS module are higher energy level, larger energy density, and higher efficiency.

XRAM Pulse Current Generator With Magnetic Flux Compression Effect

The dual representation of MARX (XRAM) pulse current generator with magnetic flux compression effect is a novel circuit for current multiplication, which has the advantages of both meat grinder and XRAM that are basic circuit topologies. It contributes to the multiplication of current in two aspects: first, increasing current by magnetic flux compression and second, the current can be increased by paralleled inductors. Compared with the standard XRAM topology, the proposed circuit topology can realize a larger factor of current multiplication more easily, and is better than the standard slow transfer of energy through capacitive hybrid meat grinder circuit topology in aspects of scalability and modularity. Meanwhile, its energy density is increased significantly, which is advantageous to the needs of actual electromagnetic launch. In this paper, theoretical analysis is done to illustrate the excellent performance of the proposed topology and preliminary experiment was conducted to demonstrate its feasibility.

Relationship Between STRETCH Meat Grinder Circuit Performances and Inductor Parameters

The slow transfer of energy through capacitive hybrid (STRETCH) meat grinder circuit is a widely used topology in inductive pulse power supply. Therefore, it is important to understand the relationship between the STRETCH meat grinder performances and the inductor parameters when improving the system performance and designing the inductor. From the perspective of inductor designing, this paper uses four indicators to present the STRETCH meat grinder performances, i.e., the charging current, the current amplification, the inductor energy density, and the discharge efficiency, and uses two indicators to present the inductor parameters, i.e., the total inductance and the ratio of the inductance $L_{1}$ to $L_{2}$ . First, the meanings of the indicators are explained or defined. Second, simulations and experiments are carried out, respectively, to analyze the trends of the four performance indicators along with the changes of two parameters indicators. Finally, both simulation and experiment results show that the increase of the total inductance leads to the decrease of the charging current and the discharge efficiency; moreover, the increase of the ratio of the inductor $L_{1}$ to $L_{2}$ leads to the increase of the current amplification and the discharge efficiency, but causes the decrease of the inductor energy density.

The Influences of Low Temperature on System Performance of Inductive Pulsed Power Supplies

To improve the efficiency of inductive pulsed power supplies (IPPS), liquid-nitrogen (LN2) cooling has been recommended to limit the energy loss. However, the low-temperature environment not only significantly reduces the resistances of the inductors but also slightly reduces their inductances. To fully evaluate the overall impacts of low temperature, eight performance indices are proposed, i.e., charging time $T_{0}$ , efficiency $\eta $ , primary/secondary current multiplication ratio $m_{1}/m_{2}$ , ratio between the maximum capacitive energy and the total inductive energy $\eta _{C}$ , maximum voltage across the main switch $U_{\mathrm{ Sopm}}$ , muzzle velocity proportional term $\propto {v}$ , and total energy loss caused by the inductors’ internal resistance $E_{R}$ . Using the typical slow transfer of energy through the capacitive hybrid circuit topology as an example, a semianalytical parametric analysis method is proposed to analyze this multiparameter problem. The results indicate that whether indices $m_{1}$ , $\eta _{C}$ , and $U_{\mathrm{ Sopm}}$ will be improved or worsened after adopting low temperature depends on specific system parameters, while the other five indices will be improved for any inductor and system parameter. Furthermore, by using a theory of equivalent inductance, the results are explained qualitatively. A test platform that introduces the LN2 cooling is established for verification, and the results agree well with the theory. The proposed semianalytical method can also be extended to any time subsection circuit topologies of IPPS for the performance analysis.

Determining Key Parameters for the STRETCH Meat Grinder Circuit

Slow transfer of energy through capacitive hybrid (STRETCH) meat grinder circuit, which was proposed by the Institute for Advanced Technology, added a capacitor into the traditional meat grinder circuit. Even though its energy density is slightly less than the corresponding pure inductance system, it can reduce the voltage across the opening switch and maintain the high multiplication factor of the opening current. The performance of the STRETCH meat grinder circuit depends on multiple parameters. The inductance ratio (n = L 1 /L 2 ) and the capacitance (C) are the two vital factors, which have a crucial influence on the system performance, such as the voltage over the opening switch (VSopm), the current multiplication factor (m), and the ratio of the maximum capacitive energy over the total inductive energy (η). Thorough studies have been carried out in this paper on the relationship between the above two factors and the three performance criteria. This paper also discusses and analyzes the chosen of the key parameters (n and C) for a single-stage STRETCH meat grinder with 2-mH total inductance, which is made up of two serial coils with 0.95 coupling factor. The opening current of the main switch is 1 kA, which constitutes a 1-kJ inductive pulsed-power supply. It fully takes the advantage of the STRETCH meat grinder topology, intensifies the study of the inductive pulsed-power supply with higher energies, and is easy to be utilized for practical application.

Study on the Collaborative Triggering of Multiple STRETCH Meat Grinder With ICCOS Modules

The energy density of the inductive energy storage systems is one order of magnitude higher than that of the capacitive ones. The slow transfer of energy through capacitive hybrid (STRETCH) meat grinder with inverse current commutation with semiconductor (ICCOS) devices put forward by Tsinghua University is a typical inductive pulsed-power supply for electromagnetic launch system, which has remarkable current amplification ability as a single module. However, one module cannot provide enough amplitude and width for the load current of the railgun launching. Therefore, the collaborative work of multiple inductive source modules is necessary for practical usage. In this paper, the designed inductive power supply system of about 1 MJ is composed of 40 STRETCH meat grinders with ICCOS modules. All the main switches are opened simultaneously to reduce the magnetic field coupling among the modules and make the current rising edge steep. The modules are divided into several groups. The triggering delays of the thyristors between every two adjacent groups are carefully designed. After the first triggers for all the modules, the energy stored in the capacitors can be further utilized with the second triggers. The numerical simulation results show that the appropriate collaborative triggering delay can increase the adjustability of the output current width and the second triggers can further increase the current width and the system efficiency. Therefore, the load current with flat shape, appropriate amplitude, and longer duration can be provided with modular design and collaborate triggering discharge of the multiple modules. This can provide a theoretical foundation for the future study and implementation.

System Implementation and Testing of the STRETCH Meat Grinder With ICCOS

By applying the principle of inverse current commutation with semiconductor (ICCOS) devices in a slow transfer of energy through capacitive hybrid (STRETCH) meat grinder system, a novel circuit topology called STRETCH meat grinder with ICCOS was proposed by the Tsinghua University in 2013. It can not only raise the amplitude of the opening current, but also reduce the cost of the STRETCH meat grinder circuit obviously by replacing the integrated gate-commutated thyristor (IGCT) with thyristor. This paper discusses the overall design, system implementation, and testing results of a STRETCH meat grinder with ICCOS system with roughly 1-kJ inductive energy. The load is a spiral coil with 1.4-mΩ resistance and 1.4-μH inductance. With closed-loop control strategy, the system detects the charging current of the inductors. When it reaches the designated value, the triggering signal for ICCOS is delivered and after the predefined delay time, the triggering signal for discharging the voltage on the pulseforming capacitor is delivered. The current of the inductors and the load are measured by Rogowski coils. The opening current is 1 kA and the maximum load current is close to 4 kA. All the voltages on the switches are lower than 1 kV. The experimental results are consistent with the simulated ones, which verified the correctness of the theoretical analysis and proved the applicability of the STRETCH meat grinder with ICCOS for larger energy level.

Structural Parameter Optimization of Inductors Used in Inductive Pulse Power Supply

Structural parameters directly affect the energy density and the total resistance of the inductors used in inductive pulse power supply (IPPS). This paper elaborates the relationship between the structural parameters and electrical performances of the inductors used in IPPS and set up the inductors for the experiment in slow transfer of energy through capacitive hybrid meat grinder circuit using air-core flat spirals of strip coil. Then we compile a program that can obtain the structural parameters of the inductors that have the highest energy density under the condition of given charging and discharging currents as well as inductances in the primary and secondary sides. The calculation results of the program are analyzed and verified by the measured values of the real inductors. At the end, on the condition of a constant current density, we put forward a rule that along with the increase in the system energy, the energy density of the IPPS became higher and the resistance of the inductors became lower.

Force sensing model of capacitive hybrid touch sensor using thin-film force sensor and its evaluation

This paper suggests the concept model of hybrid touch sensor that can detect touch locations and each force component in case of single or two-point touch event. The model is to calculate each force component using known touch locations obtained from commercial projective capacitive touch module. The suggested model consists of four thin-film force sensors and a tempered glass plate instead of commercial capacitive touch sensor. The force sensors are fabricated easily by simple screen printing technique and evaluated by calibration setup. Eleven single-touch events are performed to obtain the maximum deviation error of force responses with respect to touch locations. Additionally, we perform two-point touch events using a transitional load and a dead weight load (50 g or 100 g) to verify the proposed hybrid touch model. The obtained force components are compared with two input loads. It is confirmed that the hybrid touch sensor can provide satisfactorily the location of contact and the force response. Finally, we expect that the proposed touch model can detect the touch locations and force components simultaneously in case of single or two touch events.

Parameter Analysis and Optimized Configuration of the PFU for Inductive Storage Systems

Paralleled pulse-forming units (PFUs) with different triggering delays might be a paramagnetic way for generating flat-topped current wave for electromagnetic launch. Many researchers have reported that multiple capacitive storage PFUs were implemented such current waves in laboratories. However, due to its low energy density, the applications of the capacitive pulsed-power supplies are limited. Since the inductor has advantages in energy density, the inductor pulsed-power supply becomes one of the hottest topics recently. The slow transfer of energy through capacitive hybrid meat grinder with inverse current commutation with semiconductor devices proposed by Tsinghua University has demonstrated its advantage and applicability recently. Using this kind of topology, this paper proposes the design of an inductive storage PFU with a stored energy of 100-kJ. The maximum load current reaches to 50 kA and its pulsewidth is at least 5 ms. The optimized inductive storage PFU shows superiority in contrast to the capacitive storage PFU with the same energy. This paper offers the theoretical analysis and the testing foundation for investigating the inductor pulsed-power supply with higher energy.

STRETCH Meat Grinder With ICCOS

Inductive pulse power supplies are of interest because their energy densities are one order of magnitude higher than those of capacitive power supplies, based on the same power-output capacity. The Institute of Advanced Technology puts forward an inductive pulse power topology called the slow transfer of energy through capacitive hybrid (STRETCH) meat grinder. In this topology, an active switch is used to cut off the charging current. Limited by the current turning off ability of integrated gated commuted thyristor, it may encounter difficulties in extending to higher-energy systems. Other than that, the cost of the system is very high. In this paper, the principle of the STRETCH meat grinder is presented. Then, the STRETCH meat grinder with inverse current commutation with semiconductor devices (ICCOS), which is proposed by the Institute of Saint Louis, is presented. The process of ICCOS in the STRETCH meat grinder is illustrated in detail. Finally, simulations are made based on Simplorer 8 to explain how ICCOS works clearly. A preliminary discussion of how to design ICCOS is also presented. We conclude that the STRETCH meat grinder with ICCOS removes the limitations of the original one and has potential applications for high-energy systems in future and can cut down the cost greatly.

Comparisons of Three Inductive Pulse Power Supplies

The energy density of the inductive energy storage systems is one order of magnitude higher than that of the capacitive ones. Therefore, they have potential applications in the future. In this paper, three inductive pulse power supply (PPS) topologies, i.e., slow transfer of energy through capacitive hybrid meat grinder, XRAM, and nonmutual inductance PPS, are discussed in depth. First, their principles are analyzed. Then, simulations are made to illustrate the principles and prepare the fundamental data for further comparisons based on a 4-kA charging current, 220-μH total inductance system under the environment of Simplorer 8. Five performance indices reflecting their performances from different aspects are proposed in order to ensure objective and comprehensive comparisons. Based on those indices, the advantages and disadvantages of these topologies are pointed out and some potential improvements are also presented.

Research of Self-Study Arithmetic on Energy Recovery Brake Pedal in Hybrid Cars

This study summarizes the necessity of researching brake pedal in hybrid cars, analyzing the shortcomings in self-study algorithm of capacitive hybrid cars and puts forward the improved algorithm to brake pedal self-study, combined with capacitive hybrid cars. Braking effects with the self-study algorithm control software are proved through the experiment.

Design, Construction, and Testing of an Inductive Pulsed-Power Supply for a Small Railgun

Advances in high-power-density batteries have rekindled interest in using inductive store as a pulse compression system. Although these batteries are considered very power dense, they lack over an order of magnitude of power density to drive a deployable electric gun. However, one can add an inductive circuit to a battery bank to make a hybrid system that has a much higher power density than batteries alone. A battery-inductor hybrid pulsed-power supply boasts several advantages over pulsed alternators, as inductors are static and relatively easy to cool. Inductors are potentially more energy dense than capacitors, making a battery-inductor hybrid pulsed-power supply an attractive alternative to capacitor-based pulsed-power supplies. The opening switch has been a major obstacle in previous inductive store projects, but in simulation, a new circuit topology-the Slow Transfer of Energy Through Capacitive Hybrid (STRETCH) meat grinder-greatly attenuates the problem. This paper discusses the design, construction, and testing of a small-scale STRETCH meat grinder system, which was successfully used to power a miniature railgun