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A Resonant DC–DC Transformer With Zero Current Ripple
Abstract
The paper presents a resonant converter topology capable of providing zero ripple conditions at either its input or output current. The basic properties of the proposed topology are discussed in detail. The remarkable symmetry and the proportional voltages of the circuit allow it to maintain ripple-less current independent of the load or switching frequency. Theoretical predictions are well supported by simulation and experimental results.
... It was reported that an inductor core bias technique (ICBT) exhibited some smaller current ripple than the traditional inductance-neutral approach did [21]. Other methods were also proposed to reduce the output ripple of the converter [22][23][24][25]. Unfortunately, their transient responses are always unsatisfactory. ...
... On the other hand, it aids the advanced controllers, functions of duty cycles, to achieve more ambitious control goals because energy storage elements have been selected optimally. So, the proposed approach offers opportunities to enrich the family of parameter design methods [12][13][14][15][16][17][18][19][20][21][22][23][24][25] and empower the family of the control designs [31][32][33][34]. Admittedly, some challenges remain. ...
Abstract DC/DC converters are ubiquitous in renewable energies such as photovoltaic power systems. A novel and general approach is proposed that consists of three matching principles, which enables one to assign a best set of energy storage elements to a DC/DC converter to meet both desirable transients and small ripples, facilitating the design of a controlled DC/DC system. First, the principle of specification matching introduces a ‘virtual’ lower order model to meet the prescribed specifications. Second, the rule of order matching augments the ‘virtual’ model to a higher order, the same as that of the actual DC/DC circuit if necessary. Third, the principle of parameter matching helps derive desirable element parameters through solving an optimization nonlinear function with constraints. These principles are realized through a specific design method for boost DC/DC converters of a photovoltaic power system. Given some specifications, a numerical optimal design is executed to verify the effectiveness of the specific design tool as well as the proposed theory. A photovoltaic power system with the designed boost DC/DC converter is implemented in both the simulated environment and the physical environment.The experimental results show that both transient responses and steady state responses (or ripples) meet the given specifications. The proposed theory can either work alone in simple designs or assist in advanced control designs for a better performance.
Power electronics has evolved from being only present in a few applications such as variable speed drives in the 1970s to becoming ubiquitous, present in almost every industrial application, and powering our daily life. In this ever-expanding market, power converters have become a mature technology covering a wide range of applications, providing solutions from a few watts (e.g., LED drivers) to gigawatts (e.g., high-voltage direct current systems). Competition has driven technology development in pursuit of cost reduction, increased efficiency, performance improvements, high power quality, higher power density, reliability, and an accelerated time to market. To meet these requirements, power converter design has been driven toward a more modular approach based on embedded systems, intelligent power modules, and power electronics building blocks (PEBBs)
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Efficiency and reliability are the two key design parameters when designing induction heating (IH) systems. A parallel quasi-resonant current source inverter (CSI) is proposed to optimise the converter efficiency and to take advantage of the inherent protection of CSIs. The proposed converter uses a coupled inductor, already present in the system to produce the IH phenomena, in order to reduce the current through the power devices and to ensure zero voltage switching during turn on and turn off transitions. As a consequence, the proposed converter significantly improves the IH system efficiency. An analytical model is proposed to study both operating conditions and efficiency. In addition to this, a 2.2-kW prototype has been designed and implemented to verify the proposed model and to prove the converter feasibility. To utilise the converter at most, SiC metal-oxide semiconductor field-effect transistors have been used, obtaining up to 98.6% efficiency at resonant conditions.
A high-efficiency high step-up dc-dc converter is proposed for renewable energy harvesting, where the sustainable power sources, such as PV panels and fuel cells, are characterized by low-voltage high-current output. The proposed converter employs the current-fed half-bridge structure to generate a square-wave current source. Then, a multiresonant tank is used to provide high voltage gain, absorb the parasitic parameters of the transformer, and create zero-current switching (ZCS) condition for all primary switches. By applying a single capacitor instead of LC for the output filter, the maximum voltage of the resonant capacitor is clamped to the output voltage, which reduces the circulating energy within the circuit and offers ZCS to the rectifying diodes. The operation principle is introduced and the steady-state analysis is also carried out for the derivation of the dc voltage gain and the ZCS conditions of the primary switches. The performance of the proposed converter was verified by a 150-W prototype. A peak efficiency of 95.2% was achieved by running the prototype at 255 kHz with 23-V input and 350-V output.
A high efficiency high step-up dc-dc converter is proposed for renewable energy harvesting where the sustainable power sources such as PV panels and fuel cells are characterized by low-voltage, high-current output. The proposed converter employs the current fed half-bridge structure to generate a square wave current source. Then, a multi-resonant tank is used to provide high voltage gain, absorb the parasitic parameters of the transformer and create zero-current switching (ZCS) condition for all primary switches. By applying single capacitor instead of LC for the output filter, the maximum voltage of the resonant capacitor is clamped to the output voltage which minimizes the circulating energy within the circuit and offers ZCS to the rectifying diodes. The performance of the proposed converter was verified by a 150 W prototype. A peak efficiency of 95.2% was achieved by running the prototype at 255 kHz with 23 V input and 350 V output.
A high efficiency high step-up dc-dc converter is proposed for renewable energy harvesting where the sustainable power sources such as PV panels and fuel cells are characterized by low-voltage, high-current output. The proposed converter employs the current fed half-bridge structure to generate a square wave current source. Then, a multi-resonant tank is used to provide high voltage gain, absorb the parasitic parameters of the transformer and create zero-current switching (ZCS) condition for all primary switches. By applying single capacitor instead of LC for the output filter, the maximum voltage of the resonant capacitor is clamped to the output voltage which minimizes the circulating energy within the circuit and offers ZCS to the rectifying diodes. The performance of the proposed converter was verified by a 150 W prototype. A peak efficiency of 95.2% was achieved by running the prototype at 255 kHz with 23 V input and 350 V output.
A modified current-fed push-pull parallel resonant inverter (CFPPRI), that includes diodes in series with the switches, was analyzed and tested by simulation and experimentally. The modified power source is capable of producing a low THD output voltage within a relatively wide frequency range. A comparison between the modified topology and the basic CFPPRI, in terms of output signal quality and efficiency was carried out. It was found that the modified inverter is more efficient and that it produces an output signal that is less distorted as the running frequency deviates from resonance. Operation with a capacitive load in an off-resonance mode was demonstrated by driving a rotary piezoelectric motor by the modified inverter
The characteristics of a push-pull parallel resonant converter
(PPRC) when operated as a DC-DC transformer were investigated
theoretically and experimentally. In the DC-DC transformer region, the
voltage transfer ratio was found to be practically constant and
independent of the input voltage and load. In this mode, all the
switching elements operate in the zero voltage switching (ZVS)
conditions. This helps to achieve high efficiency at high switching
frequencies Another important feature of the proposed DC-DC transformer
is the ability to be driven by an arbitrary switching frequency,
provided that it is lower than the self-oscillating frequency. This
permits the synchronization of the converter to a master clock to obtain
a stable signal spectrum of a desired base frequency. The analytical
expressions for the peak voltages and currents derived are applied to
the converter. The proposed topology was tested experimentally on a 100
W unit which was run in the 200 kHz frequency region
A new self-adjusting current-fed push-pull parallel inverter (SA-CFPPRI) is presented and tested by simulation and experimentally. The power source includes a soft switching control circuitry and a controllable inductor. The SA-CFPPRI can drive a capacitive load at any frequency within the design range. It will maintain zero voltage switching of the main transistors and follow the input frequency signal even when the resonant elements and/or the load vary. Possible range of applications for the proposed power source is: piezoelectric transformers and motors, ac bus for a distributed power system and other loads that need to be fed by a sinusoidal waveform. The experimental results of the laboratory unit (160 Vrms at 93 kHz and nominal output power of 5W) verify the analytical analysis and proposed design procedure.
Switching power supplies, due to their high-frequency switching
operation, draw a substantial amount of input ripple current. Such
ripple current manifests itself as electromagnetic interference (EMI).
Active and passive ripple cancellation methods have been proposed in the
past. This paper discusses the cancellation methods, and classifies the
basic circuit configurations for ripple current cancellation. The basis
of discussion is a “nullification” process, which can be
described effectively in terms of the ideal circuit element nullor. The
initial focus is on differential-mode noise cancellation, but the basic
technique can be applied equally to cancelling common-mode noise. The
classification provides a clear guideline for synthesizing practical
cancellation circuits. Both active and passive implementation examples
are given and experimentally demonstrated
A novel topology, current-sourcing push-pull parallel-resonance
inverter (CS-PPRI) was investigated theoretically and experimentally.
The proposed power stage is built around a current fed push-pull
inverter. The main features of the proposed inverter are: a load
independent output current and zero voltage switching (ZVS). It is
suggested that the proposed CS-PPRI is a viable alternative for
realizing electronic ballasts for low and high-intensity discharge lamps
In the past the majority of power processing applications have been centered around a very few standard switching converter topologies. Recently, a number of new converter topologies have been proposed in order to find the best possible electrical inter connection of power processing elements: switches, storage components, and transformers, that would yield the highest efficiency and best performance. However the equally important and complementary problem of their best magnetic interconnection has been completely overlooked. In some new converter structures, the nature of the switching process and existing waveforms allows integration of previously separate inductors and transformers into a single magnetic structure. Several such magnetic core structures are proposed and analyzed, which lead to further converter simplifications and performance improvements.
Results of a theoretical and experimental investigation of a capacitive-loaded push-pull parallel-resonant dc-dc converter (CL-PPRC) are presented and discussed. The push-pull parallel-resonant converter (PPRC) is driven by a lower than resonance frequency and the secondary voltage is rectified and smoothed by a capacitive filter. The CL-PPRC is shown to operate in the zero voltage switching (ZVS) mode with a boost-like dc transfer ratio which is approximately linear with the period of the switching frequency. Experimental results of a 180 W, high output voltage (1.8 KV) prototype where found to be in good agreement with the analytical analysis, models, and simulation results presented in this work. The basic characteristic of ZVS, the fact that the resonant current is passing through the switches only during a fraction of the period, the high voltage transfer ratio, and the inherent input/output isolation, make the newly proposed topology a viable design alternative in avionic and aerospace applications.
Alternative planar construction approaches for blending the
various power magnetic components of switch mode power processing
circuits and systems are presented. These unique approaches are based on
the use of stacked ferrite core pieces, which provide common flux paths
for transformer and inductor operations, arranged so as to minimize
magnetic interactions and core material required in these common paths.
A construction example for a 50-watt DC-to-DC switch mode converter is
detailed, consisting of a three-chamber cylindrical planar ferrite fore
structure that accommodates all power magnetic functions, including
input filter inductance. Means to enhance leakage inductances between
inductor windings for reduction of AC ripple current magnitudes are also
explored
Leakages are inseparably associated with magnetic circuits and are always thought of in three different negative ways: either you have them and you don't want them (transformers), or you don't have them but want them (to limit transformer short circuit currents), or you have them and want them, but you don't have them in the right amount (coupled-inductor magnetic structures). The methods of how to introduce the leakages at appropriate places and in just the right amounts in coupled-inductor magnetic structures are presented here, in order to optimize the performance of switching dc-to-dc converters.
Coupled magnetics filter techniques are important tools in a
converter designer's arsenal, but are not well understood. Evidence of
this is one basic building block of coupled filters, reinvented numerous
times during the past 65 years. A detailed analysis of coupled magnetics
for DC-DC converters, based on a key building block, is given
Based on a short summary of the theoretical basics of the
zero-ripple current phenomenon a special zero input current ripple boost
converter topology as presented in the literature is investigated. It is
shown that the complete suppression of the input current ripple of the
system is only given in a theoretical extreme case. For a practical
realization only such a ripple reduction of the input current of the
basic converter structure is obtained as corresponds to a simple
low-pass input filter. This is proven by a detailed analysis also for a
zero-ripple Cuk and for a zero-ripple SEPIC converter structure.
Furthermore, it is shown that the realization of a zero-ripple Cuk or
zero-ripple SEPIC converter is not linked to a magnetic coupling of the
input and output inductors, but can also be achieved by a simple
rearrangement of the elements of the basic converter structures. There
one can see that the operating behavior of a zero input current ripple
SEPIC converter is equivalent to the operating behavior of a buck-boost
converter stage with LC input filter. Finally, the advantages and
disadvantages of the different realization approaches of zero-ripple
topologies are compared. Also, an outlook towards the planned further
treatment of the topic is given
A new family of quasi-square wave and multiresonant zero voltage
switching (ZVS) converters featuring integrated magnetics is introduced.
These converters combine the advantages of the high frequency zero
voltage switching of the resonant approach and the zero-ripple property
of the integrated magnetics approach. The proposed quasi-square wave ZVS
converters have a wider voltage conversion range than previous
quasi-square wave converters. The key to these topologies is the fact
that all magnetic devices such as tank inductor, filter inductors, and
transformer are effectively in parallel. Therefore, all of these
elements can be wound on the same core, with core size determined by the
requirements of the tank inductor. Hence, the size of the converter can
be reduced dramatically. Simulation and experimental results are
presented
The results of a theoretical and experimental investigation of a capacitive-loaded push-pull parallel-resonant DC-DC converter (CL-PPRC) are presented and discussed. The converter is driven by a lower than resonance frequency, and the secondary voltage is rectified and smoothed by a capacitive filter. The CL-PPRC is shown to operate in the zero voltage switching (ZVS) mode with a boostlike DC transfer ratio which is approximately linear with the period of the switching frequency. Experimental results of a 180 W, high output voltage (1.8 kV) prototype are in good agreement with the analysis, models, and simulation results presented. The basic characteristic of ZVS, the fact that the resonant current is passing through the switches only during a fraction of the period, the high voltage transfer ratio, and the inherent input/output isolation, make the newly proposed topology a viable design alternative in avionic and aerospace applications
Coupled inductor techniques supply a method to reduce the power
converter size and weight and achieve ripple-free current. The boost
power converter is a very popular topology in industry. However, the
input-current ripple hinders efforts to meet electromagnetic
interference (EMI) requirements. In particular, the input current
becomes discontinuous and pulsating when the conventional boost power
converter operates in the discontinuous inductor-current mode. This
paper describes a boost power converter which has the same discontinuous
properties as the conventional boost power converter. However, the
proposed boost topology has continuous or ripple-free input current when
it operates with discontinuous inductor-current. The proposed topology
is compared with traditional converter topologies, such as the Sepic and
Cuk power converters. Simulation results are presented. The prototype is
built to demonstrate the theoretical prediction. The proposed boost
topology is simple, with straightforward control [the same as
pulse-width modulation (PWM)]
When low ripple is required from a switched mode dc-dc converter, dissipative active filters offer an alternative to passive LC and coupled inductor filters. Analytical and experimental results are presented for a simple active ripple filter. The filter employs a pair of current transformers as sensors for feedforward and feedback control and two metal-oxide-semiconductor field-effect transistors (MOSFETs) as cancellation current drivers. Measurements demonstrate good ripple attenuation up to 5 MHz, more than 70 dB being obtained at 100 kHz, the switching frequency of a test converter. The overall efficiency was measured as 95%, with room for further improvement. The filter is suitable for input and output smoothing in dc-dc converters for aerospace and other critical applications.
The generalized use of integrated magnetics and zero-ripple techniques in switchmode power converters
- G E Bloom
- R P Sevems
G. E. Bloom and R. P. Sevems, " The generalized use of integrated mag-netics and zero-ripple techniques in switchmode power converters, " in Proc. IEEE PESC'84, Jun. 1984, pp. 15–33.
Modern DC-to-DC Switch mode Power Converter Circuits
- R P Severns
- G Bloom
R. P. Severns and G. Bloom, Modern DC-to-DC Switch mode Power Converter Circuits. New York: Van Nostrand Reinhold, 1984, ch. ch. 12, pp. 262–324.
Bloom Modern DC-to-DC Switch mode Power Converter Circuits
- R P Severns
A Resonant dc–dc Transformer
- G Ivensky
- A Abramovitz
- M Gulko
- S Ben-Yaakov