Top PDF Active power sharing in input-series-input-parallel output-series connected DC/DC converters

Active power sharing in input-series-input-parallel output-series connected DC/DC converters

Active power sharing in input-series-input-parallel output-series connected DC/DC converters

or medium-frequency (MF) for galvanic isolation [2, 3], allows the heavy line-frequency transformer in an AC grid to be eliminated, leading to significant weight and size savings and much less investment in copper and core material. For example, the estimated mass of a 1MVA medium-frequency (4kHz) transformer is 150kg, whereas that of a 1MVA 50Hz transformer is 3 tons [4]. With series-output connection, the turns-ratio of the isolation transformer can be reduced, leading to a reduction in leakage inductance. Additionally, modular DC/DC converters offer more compact and lighter designs in situations where a single high-voltage converter with series connection of switches can be replaced with a set of low-voltage converter modules as being discussed in this paper. It will also solve the problem of additional snubber component and more complex gate drive units caused by the series connection of switches [5]. Compared to DC/DC converter based modular multilevel converter (MMC), re- configurability and potential for interleaved control may make the ISIPOS DC/DC converter an attractive choice in medium-voltage applications. ISIPOS connection of multiple low-voltage modules provides an excellent solution for scalability of DC/DC converters, with improved robustness and possibility of fault-tolerant operation. Modular architectures offer further advantages, including internal fault management and module reconfiguration as a result of ‘n+k’ designed redundancy and the use of power electronic building blocks (PEBB) to reduce production [6-8].
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PV based High Step-up Input-Parallel Output-Series DC/DC Converter with Dual Coupled Inductors

PV based High Step-up Input-Parallel Output-Series DC/DC Converter with Dual Coupled Inductors

Another method for achieving high step-up gain is the use of the voltage-lift technique, showing the advantage that thevoltage stress across the switch is low. However, severaldiode-capacitor stages are required when the conversion ratiois very large, which makes the circuit complex. In addition,the single switch may suffer high current for high powerapplications, which risks reducing its efficiency.Another alternative single switch converters includingforward, fly-back and tapped-inductor boost can achieve highconversion ratio by adjusting the turns ratio of the transformer, but these converters require large transformer turnsratio to achieve high voltage gain. In, an integratedboost-flyback converter is proposed to achieve high voltagegain, and the energy of a leakage inductor is recycled into theoutput during the switch-off period. Unfortunately, the inputcurrent is pulsed from the experimental results. In addition, itshould be noticed that the low-level input voltages usuallycause large input currents and current ripples to flow throughthe single switch for high step up and high power dc-dcconversion, which also leads to increasing conduction losses [9-10].
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Operation and control design of an input-series-input-parallel-output-series conversion scheme for offshore DC wind systems

Operation and control design of an input-series-input-parallel-output-series conversion scheme for offshore DC wind systems

Overall, the system under investigation can be viewed as a two- stage power converter, as shown in Fig. 1b. For such a system, controller design becomes complex for several reasons. The overall system bandwidth of the power transfer controller is restricted to guarantee that undesired voltages and currents at the resonance frequencies are not excited because of the existence of the resonant poles. Consequently, the dynamics and transient response of the system are limited. In addition, other control loops should be inserted to assure equal current and voltage sharing between the series and parallel modules. These loops should respond more quickly than the main power controller and should not interact with it. This adds to the complexity of the control design process. In this context, the control system can be divided into two parts:
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A High Gain Input Parallel Output Series DC/DC Converter With Dual Coupled Inductors
Palusa Mahesh Goud & Rosaiah Mudigondla

A High Gain Input Parallel Output Series DC/DC Converter With Dual Coupled Inductors Palusa Mahesh Goud & Rosaiah Mudigondla

High voltage gain DC-DC converters are required in many industrial applications such as PV and fuel cell energy systems, high intensity discharge lamp(HID), DC back-up energy systems and electric vehicles. This paper presents a novel input-parallel output- series boost converter with dual coupled-inductors and a voltage multiplier module. On the one hand, the primary windings of two coupled-inductors are connected in parallel to share the input current and reduce the current ripple at the input. On the other hand, the proposed converter inherits the merits of interleaved series-connected output capacitors for high voltage gain, low output voltage ripple and low switch voltage stress. Moreover, the secondary sides of two coupled-inductors are connected in series to a regenerative capacitor by a diode for extending the voltage gain and balancing the primary-parallel currents. In addition, the active switches are turned on at zero-current and the reverse recovery problem of diodes is alleviated by reasonable leakage inductances of the coupled inductors. Besides, the energy of leakage inductances can be recycled. A prototype circuit rated 500W output power is implemented in the laboratory, and the experimental results shows satisfactory agreement with the theoretical analysis.
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A Solar PV Based Input Parallel Output Series DC/DC Converter with Improved Voltage Gain
Sreekanth Reddy Kashireddy & Mr N Ravi

A Solar PV Based Input Parallel Output Series DC/DC Converter with Improved Voltage Gain Sreekanth Reddy Kashireddy & Mr N Ravi

In many industrial applications High voltage gain DC-DC converters are required such as PV and fuel cell energy systems, high intensity discharge lamp (HID), DC back-up energy systems and electric vehicles. This paper presents a novel solar PV based input-parallel output-series boost converter with dual coupled-inductors and a voltage multiplier module. On the one hand, the primary windings of two coupled-inductors are connected in parallel to share the input current and reduce the current ripple at the input. On the other hand, the proposed converter inherits the merits of interleaved series-connected output capacitors for high voltage gain, low output voltage ripple and low switch voltage stress. Moreover, the secondary sides of two coupled- inductors are connected in series to a regenerative capacitor by a diode for extending the voltage gain and balancing the primary-parallel currents. In addition, the active switches are turned on at zero- current and the reverse recovery problem of diodes is alleviated by reasonable leakage inductances of the coupled inductors. Besides, the energy of leakage inductances can be recycled. A prototype circuit rated 500W output power is implemented in the laboratory, and the experimental results shows satisfactory agreement with the theoretical analysis.
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Key Terms- Current sharing, droop control method, DC microgrid, parallel DC-DC converters. voltage regulation.

Key Terms- Current sharing, droop control method, DC microgrid, parallel DC-DC converters. voltage regulation.

In parallel DC-DC converters there is uniform current distribution in case of proper current sharing hence no circulating current occurs in the parallel system. At the same time realisation of a voltage drop in converter output voltage due to inclusion of series resistance. Hence, DI is expressed as a function of power output loss and current sharing difference .

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Power sharing of parallel operated DC-DC converters using current-limiting droop control

Power sharing of parallel operated DC-DC converters using current-limiting droop control

Abstract— In this paper, a nonlinear current-limiting droop controller is proposed to achieve accurate power sharing among parallel operated DC-DC boost converters in a DC micro- grid application. In particular, the recently developed robust droop controller is adopted and implemented as a dynamic virtual resistance in series with the inductance of each DC-DC boost converter. Opposed to the traditional approaches that use small-signal modeling, the proposed control design takes into account the accurate nonlinear dynamic model of each converter and it is analytically proven that accurate power sharing can be accomplished with an inherent current limitation for each converter independently using input-to-state stability theory. When the load requests more power that exceeds the capacity of the converters, the current-limiting capability of the proposed control method protects the devices by limiting the inductor current of each converter below a given maximum value. Extensive simulation results of two paralleled DC-DC boost converters are presented to verify the power sharing and current-limiting properties of the proposed controller under several changes of the load.
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Multiple Input DC-DC Converters with Input
Boost Stages

Multiple Input DC-DC Converters with Input Boost Stages

A high voltage gain DC-DC converter is introduced that can offer a voltage gain of 20, i.e., to step up a 20V input to 400V output. The output voltage, switching stress, inductor current and capacitor voltage are observed. Output voltage of 400V was obtained during the simulation. The observed values from the simulation are similar to the calculated values. Compared to the classical DC-DC converters the voltage stress across switches is low. The voltage across the switch was 80V which is a small value com- pared to the output voltage. The current through S 2 shows a spike because of the voltage imbalance between different voltage multiplier stages. The size of the converter would be less because high frequency operation and absence of winding transformer. On comparing with resonant converter the absence coupled inductor makes this converter superior, since leakage flux and stray magnetic field loss is not present. Since it is a multi-port converter with a high voltage gain, independent sources can be connected and power sharing, MPPT algorithms can be implemented independently at each input port. The main problem associated with the proposed converter is that, as the stages increases the size of capacitor becomes large. Thus making the circuit bulky. The converter finds its application in integration of individual solar panels onto the 400V distribution bus in data centers, telecom centers, DC buildings and microgrids. Hardware prototype of 2W, 10 kHz of the base circuit [1] was implemented.
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A High Gain Input Parallel Output Series Dc/Dc Converter with Dual Coupled Inductors
K Kumara Swamy

A High Gain Input Parallel Output Series Dc/Dc Converter with Dual Coupled Inductors K Kumara Swamy

Basic sense voltage can be changed to provide increased, with a very high duty ratio is not final. In practice, power, inductor and capacitor component of parasitic elements is more limited effort. In addition, very high cycle duties of running the opposite direction to recover increases conduction losses, dual LED rectifier current and big waves that can induce serious problem. On the other hand, usually in a high output voltage and high energy conversion large current input, low voltage master key after the stress voltage can not resist a little special with device power rating and diode, respectively output In switching voltage is equal to traditional push. Many topology to increase high- voltage step-up boost Traditional alternatives offered on the basis of a visit. The paper output batch of high steps and a series of high-energy processes with double coil side is proposing to change the input parallel. This configuration will benefit from high-voltage, low output voltage ripple, and stress the key advantages of low voltage across the power gets. In addition, Converter Integrated inductors reasonable inductance leakage diodes key problem of reverse recovery current of the current active zero level and have been able to overcome.
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A CUK Converter Based High Gain Input-Parallel Output-Series Dc/Dc Converter Vijiyo Wilson, MD. Saravanan

A CUK Converter Based High Gain Input-Parallel Output-Series Dc/Dc Converter Vijiyo Wilson, MD. Saravanan

The AC/DC converters consist of power electronics devices like Insulated Gate Bipolar Transistors (IGBT) or Gate Turn-Off thyristors (GTO) that are characterized by switch mode operation. The capability of forming sinusoidal currents is provided by the introduction of the sophisticated technique called Pulse-Width Modulation (PWM). This technique provides the sequences of width-modulated pulses to control power switches. Many PWM techniques have been developed according to special requirements and optimization criteria. The choice of the particular PWM technique arises from the de-sired performance of the synchronous rectifiers. Generally pulse-width modulation techniques for frequency converters may be classified as follows: Carrier-Based Sinusoidal PWM, Hysteresis-Band PWM, Space Vector PWM, Selected Harmonic Elimination PWM, Minimum Current Ripple PWM, Sinusoidal PWM with Instantaneous Current Control and Random PWM.
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A High Gain Input-Parallel Output-Series Interleaved Boost Converter for Home Appliances

A High Gain Input-Parallel Output-Series Interleaved Boost Converter for Home Appliances

Voltage multipliers are AC-DC power conversion devices, comprised of diodes and capacitors that produce a high potential DC voltage from a lower voltage AC source. Multipliers are made up of multiple stages. Each stage is comprised of one diode and one capacitor. A voltage doubler uses two stages to approximately double the DC voltage that would have been obtained from a single stage rectifier.The double independent inductors in the modified interleaved boost converter are separately replaced by the primary windings of coupled inductors that are employed as energy storage and filtering as shown in Fig. 2. The secondary windings of two coupled inductors are connected in series for a voltage multiplier module, which is stacked on the output of the modified converter to get high voltage gain. This connection is also helpful to balance the currents of two primary sides.Equivalent circuit of the proposed topology is shown in Fig. 2
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PV Cell Fed High Voltage Gain Coupled Inductor Based Input Parallel Output Series DC-DC Converter for Grid Connected System

PV Cell Fed High Voltage Gain Coupled Inductor Based Input Parallel Output Series DC-DC Converter for Grid Connected System

energy conversion systems and fuel-cell systems usually need high step up and large input current dc-dc converters to boost low voltage (18-56 V) to high voltage (200- 400 V) for the grid-connected inverters. High-intensity discharge lamp ballasts for automobile headlamps call for high voltage gain DC-DC converters to raise a battery voltage of 12 V up to 100 V at steady operation. Also, the low battery voltage of 48 V needs to be converted to 380 V in the front-end stage in some uninterruptible power supplies and telecommunication systems by high step- up converters. Theoretically, abasic boost converter can provide infinite voltage gain with extremely high duty ratio. In practice, the voltage gain is limited by the parasitic elements of the power devices, inductor and capacitor. Moreover, the extremely high duty cycle operation may induce serious reverse-recovery problem of the rectifier diode and large current ripples, which increase the conduction losses. On the other hand, the input current is usually large in high output voltage and high power conversion, but low-voltage-rated power devices with small on resistances may not be selected since the voltage stress of the main switch and diode is, respectively, equivalent to the output voltage in the conventional boost converter. Many other converter topologies have developed for high step up gain. Here a high gain input-parallel output-series DC-DC converter with dual coupled inductors is designed. This configuration inherits the merits of high voltage gain, low output voltage ripple, and low voltage stress across the power switches. Moreover, the converter is able to turn ON the active switches at zero current and alleviate the reverse recovery problem of diodes by reasonable leakage inductances of the coupled inductors [11-12].
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Design of Multiple Input DC DC Converters

Design of Multiple Input DC DC Converters

A DC-to-DC converter is an electronic circuit or electromechanical device which converts a source of direct current (DC) from one voltage level to another. It is a type of electric power converter. Power levels range from very low (small batteries) to very high (high-voltage power transmission). DC -DC converter is one of the most important and widely used devices of modern power applications. Power electronics field in the last decade has been the development of switching-mode converters with higher power density and low electromagnetic interference. Light weight, small size and high power density are also some of the key design parameters. Several different types of switch-mode dc-dc converters belongs to buck, boost and buck-boost topologies, have been developed and reported in the literature to meet variety of applications . Major concern in the recent dc distribution systems, such as in automotive and telecom power supply systems, is to meet the increased power demand and reducing the load on the primary energy source, i.e. built-in battery. This is possible by adding additional power sources in parallel to the existing battery source. The additional power sources can be: (i) renewable energy sources such as photovoltaic (PV) or wind, (ii) fuel cell storage power The objective of this paper is to generate a two input topology by using pulsating source cell derived from six non isolated converter such as buck, boost buck-boost ,Cuk , SEPIC and Zeta. The single-ended primary-inductor converter (SEPIC) is a type of DC/DC converter allowing the electrical potential (voltage) at its output to be greater than, less than, or equal to that at its input. The output of the SEPIC is controlled by the duty cycle of the control transistor. A SEPIC is essentially a boost converter followed by a buck-boost converter, therefore it is similar to a traditional buck-boost converter, but has advantages of having non-inverted output (the output has the same voltage polarity as the input), using a series capacitor to couple energy from the input to the output (and thus can respond more gracefully to a short-circuit output), and being capable of true shutdown: when the switch is turned off, its output drops to 0 V . SEPICs are useful in applications in which a battery voltage can be above and below that of the regulator's intended output. For example, a single lithium ion battery typically discharges from 4.2 volts to 3 volts; if other components require 3.3 volts, then the SEPIC would be effective.
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Modular input-series-input-parallel output-series DC/DC converter control with fault detection and redundancy

Modular input-series-input-parallel output-series DC/DC converter control with fault detection and redundancy

Studies have shown that medium-voltage DC (MVDC) connection may be advantageous for long cable networks, such as the collection grid of offshore wind farms. In such cases, DC connection has the potential to deliver lower system level losses through the elimination of AC charging current and better utilization of cable capacity. Reduction in system volume and weight may also be achieved by the replacement of line-frequency transformers with medium- or high-frequency DC/DC converters [1-4]. Realizing the benefits of MVDC will require the use of high-capacity DC/DC converters capable of operating at the required network voltages, e.g. wind generator DC link voltage step up (e.g. from 5kV DC) to a level compatible with an efficient wide area network connection (e.g. 33kV DC). Although some high-efficiency DC/DC converters have been developed [5, 6], transfer of these technologies to the required network voltages is still a challenge since both the input and output of the DC/DC converter must operate above the voltage capability of existing power semiconductors. A solution to this problem is the modular connection of multiple transformer-coupled converters in which each module operates within the voltage rating of individual semiconductor devices, which can achieve high- power without compromising the efficiency and switching
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A Parallel Input Series Output  DC/DC Converter with High Voltage Gain

A Parallel Input Series Output  DC/DC Converter with High Voltage Gain

High gain dc/dc converters are widely used in many industrial applications such as solar, fuel cell, x-rays, laser and high intensity discharge lamp ballasts for automobile headlamps[2]-[4]. Theoretically, a basic boost converter is capable of providing high conversion ratio, but extremely high duty ratio is required. In practice, extreme duty ratios are not permitted because of the large conduction losses and frequent damage of power switches. Usually it is preferable to use low voltage rated power switches having low on state resistance to reduce the conduction losses, which may not be possible in a conventional boost converter. Cascaded boost converters can provide high voltage gain[5]-[6]. But high voltage stress across the switches and poor efficiency are the disadvantages. DC/DC converters using coupled inductors is a good alternative to obtain a high step up gain[7], provided the leakage inductances are handled properly. Interleaved control is found very useful in reducing the input current ripple of the converter[8]-[10]. Two different boost converter structures can be combined to produce twice the voltage gain by connecting there inputs in parallel and output in series. The two independent inductors of this combined converter is replaced by two coupled inductors. Connecting the primary windings of coupled inductors in parallel and secondary windings in series a high step up DC/DC converter is derived. An input parallel output series boost converter with dual coupled inductors can be
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Title: DESIGN OF MODIFIED SINGLE INPUT MULTIPLE OUTPUT DC-DC CONVERTER

Title: DESIGN OF MODIFIED SINGLE INPUT MULTIPLE OUTPUT DC-DC CONVERTER

Single Input Multiple Output dc-dc converter. The DC Source block consists of the dc input power source and a capacitor. The value of input is in the range of 12V. Switch Integrated with Coupled Inductor block consisting of a coupled inductor, a MOSFET switch and a diode. The coupled inductor primary has a series connected leakage inductor and a parallel connected magnetizing inductor. Output Voltage 1 Circuit consists of an auxiliary inductor, a diode and a filter capacitor. The value of output voltage 1 is 28V. Output Voltage 2 Circuit consists of a capacitor combination. In addition, the series connected diode and a filter capacitor is used. The value of output voltage 2 is 200V. Output Voltage 3 circuit consists of two MOSFET switches, two diodes and two capacitors. The value of output voltage 3 is -200V .
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Input parallel output series DC DC boost converter with a wide input voltage range, for fuel cell vehicles

Input parallel output series DC DC boost converter with a wide input voltage range, for fuel cell vehicles

[24] (when N>1). The converter in [25] benefits the lowest voltage stress for diodes among these converters. But, both the potential differences between the output and the input side grounds of the converters in [24] and [25] are high frequency PWM voltages (i.e. without a common ground), which may cause more EMI. In addition, the number of components for the proposed converter is the smallest one among these converters. Regarding the voltage-gain of converters for fuel cell vehicles, a wide range of voltage-gain is really required because the output voltage of the fuel cell varies within a wide range when the load power varies widely. Therefore, sometimes the converters need to operate with a lower voltage-gain (i.e. the duty cycle is lower due to the higher output voltage of the fuel cell). According to Tab. 3, when these converters need to achieve the required lower voltage-gain, the duty cycle of the proposed converter is proper, i.e. a wider voltage-gain range can be realized.
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A Topology for Equal Power Sharing In a Multiple Input DC-DC Converter for Hybrid Energy System

A Topology for Equal Power Sharing In a Multiple Input DC-DC Converter for Hybrid Energy System

Hybrid energy system (HES) is an e merging technology that has the potential to meet future energy require ments. Hybridisation of energy systems is gaining more and more popularity in the field of e lectr ic power systems because of its reliable operation, durability,c leanliness and efficient operation as compared with single source energy systems [1, 2]. A well designed HES provides good power handling capability during steady-state operation and better dynamic response during transients [2]. The integration of more than one energy source to form HES heavily depends on power electronic interface which integrates several energy sources having diffe rent V-I characteristic [3]. Mult iple -input DC-DC converters (MICs) are playing a significant role in interfacing and diversification of diffe rent energy sources. The energy sources like fuel cell, battery, ultra-capacitor and renewable energy sources of same or different category with distinct V-I characteristic are traditionally connected together through individual DC-DC converter and their outputs are connected to common dc bus either in series or paralle l [2, 3, 4]. However, such configurations are costly, bulky and relatively comple x in design and reduce overall efficiency as well as reliability of the system. Multiple single-input DC-DC converters can be successfully replaced by a single multip le-input DC-DC converter. MIC offers simple and more co mpact design and reduces the cost and comple xity of the system. In addition, efficient dc power distribution at regulated output voltage enhances reliability [5, 6].
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Modular input-parallel output-series DC/DC converter control with fault detection and redundancy

Modular input-parallel output-series DC/DC converter control with fault detection and redundancy

In typical applications, reliable operation of the IPOS modular DC/DC converter requires a control mechanism that ensures equal power sharing amongst the constituent modules under all conditions, including cases when module components have noticeable mismatch [14-16]. At present, the open literature contains few publications in the field of the IPOS converter and its control strategy. One topology uses the same duty cycle, generated from one outer voltage loop and one inner current loop, for all modules [17]. Although this approach offers a simple control structure, it cannot ensure power sharing between modules. This approach is not therefore suitable for medium-voltage applications, as modules may be exposed to the risk of damage from over-voltages during transients. The main weaknesses of this approach are addressed by use of a common output voltage loop, inner current loops and an output voltage sharing loop to achieve power sharing for a DC/AC converter [18]. Issues related to fault-tolerance control are not addressed. Uniform output voltage distribution across several modules has been realised using an output voltage distributed control scheme [19], but additional circuitry is required to provide fault-tolerant performance. In this paper, the overall output voltage controller builds on the Lyapunov stability law to make the system asymptotically stable. Additionally, this paper proposes a new master-slave control scheme and a distributed voltage sharing controller that ensure power sharing under all operating conditions, including during failure of the master module. To further improve performance, each module has its own sawtooth carrier, phase shifted by ±360°/n from adjacent modules.
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Modular input-parallel-output-series DC/DC converter control with fault detection and redundancy

Modular input-parallel-output-series DC/DC converter control with fault detection and redundancy

Currently, the open literature contains few publications in the field of the IPOS converter and its control strategy. Normally, the average active sharing method or the master-slave active sharing method is chosen to solve the power sharing issue under any steady-state condition with mismatched components among the modules, and other challenging conditions such as inconformity of the transfer function, switching delay and discontinuity caused by the switching time delay, and input voltage disturbance [6]. In the master- slave control method, the master module is responsible for load regulation whilst the slaves ensure equal current and voltage sharing among the modules. Compared to the average active sharing method, fault-ride-through under module failure may be achieved more simply using master-slave control, with input current and output voltage being evenly shared among the remaining healthy modules. For existing control schemes, fault detection and protection methods for input-parallel-output-series connected DC/DC converters are not reported in the literature.
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