DC-DC q-ZSC with Buck-Boost Converter Gain

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Two quasi-Z-source DC-DC converters (q-ZSCs) with buck-boost converter gain were recently proposed. The converters have advantages of continuous gain curve, higher gain magnitude and buck-boost operation at efficient duty ratio range when compared with existing q-ZSCs. Accurate dynamic models of these converters are needed for global and detailed overview by understanding their operation limits and effects of components sizes. A dynamic model of one of these converters is proposed here by first deriving the gain equation, state equations and state space model. A generalized small signal model was also derived before localizing it to this topology. The transfer functions (TF) were all derived, the poles and zeros analyzed with the boundaries for stable operations presented and discussed. Some of the findings include existence of right-hand plane (RHP) zero in the duty ratio to output capacitor voltage TF. This is common to the Z-source and quasi-Z-source topologies and implies control limitations. Parasitic resistances of the capacitors and inductors affect the nature and positions of the poles and zeros. It was also found and verified that rather than symmetric components, use of carefully selected smaller asymmetric components L1 and C1 produces less parasitic voltage drop, higher output voltage and current under the same conditions, thus better efficiency and performance at reduced cost, size and weight.

Section: Small Signal Analysismentioning

confidence: 99%

“…However, more findings are making ISCs overcome these challenges such as [54], [55] where the gain and continuous gain curve of BBC were achieved using non-isolated q-ZSC topologies. These topologies produced higher magnitude output voltages and currents than the corresponding buck-boost converters thus giving them potential advantages.…”

Section: Introductionmentioning

confidence: 99%

Dynamic model of A DC-DC quasi-Z-source converter (q-ZSC)

Ado¹,

Jusoh²,

Mutawakkil³

et al. 2019

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“…RE systems require DC-DC converters to regulate their variable output voltage to a given set point because sources like fuel cells and photovoltaic cells have unregulated outputs [8][9][10]. [11][12][13][14][15]. ISCs couple converter's main circuit to its power source, thus providing features not obtained in the traditional voltagesource and current-source converters in addition to their advantages [16].…”

Section: Introductionmentioning

confidence: 99%

“…Transformer-based impedance ISCs were proposed to increase gain and isolation at the expense of increased size, cost and weight [20][21][22]. Reference [11,12] proposed DC-DC q-ZSCs with BBC gain. These converters utilized the topologies of DC-DC q-ZSCs to achieve the voltage gain of traditional BBC.…”

Section: Introductionmentioning

confidence: 99%

Asymmetric quasi impedance source buck-boost converter

Ado

Jusoh

Sutikno

2020

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An impedance source buck-boost converter (BBC) prototype for renewable energy (RE) application in the transportation industry is proposed. Its functions include stabilizing the variable output voltage of the RE sources such as fuel cells and photovoltaic cells. The converter utilized a topology of DC-DC quasi-impedance source converters (q-ZSCs) to achieve the gain curve of the BBC. With BBC gain curve, the converter earned advantages over the two other classes of non-isolated DC-DC q-ZSCs. These advantages include ecient buck-boost capability at the ecient duty ratio range of 0:35-0:65 and continuous and non-zero gain at the ecient duty ratio range. The converter's q-ZSC topology implies using two capacitors and two inductors. These two capacitors and inductors formed two separate LC filters that provides second order filtering compared to the first order filtering in BBC. Its other advantages over the traditional BBC include elim-ination of dead and overlap-time, simple contol and permitting higher switching frequency operation. The converter is capable of utilizing high switching frequency and asymmetric components to achieve BBC gain by using smaller components to reduce cost, weight and size. Its simulation response and that of a correspond-ing BBC for some given specifications were compared, presented and analyzed. An experimental scaled-down prototype was also developed to confirm its opera-tion. Analysis of the converters responses comfirmed the prototype's second order filtering as against the first order filtering in traditional BBC.

“…Power converters convert electric energy from a magnitude or form to another [1,2]. DC-DC converters convert between DC voltages, while ac-ac converters convert between ac-signals.…”

Section: Introductionmentioning

confidence: 99%

Extended family of DC-DC Quasi-Z-Source converters

Ado¹,

Jusoh²,

Sutikno³

2019

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The family of DC-DC q-ZSCs is extended from two to three classes and four to six members. All the members were analyzed based on efficient duty ratio range (RDeff) and general duty ratio range (RDgen). Findings showed that similar to the traditional buck-boost converter (BBC), each of the topologies is theoretically capable of inverted buck-boost (BB) operation for the RDgen with additional advantages but differed according to class in how the gains are achieved. The new topologies have advantages of BB capability at the RDeff, continuous and operable duty ratio range with unity gain at contrary to existing topologies where undefined or zero gain is produced. Potential applications of each class were discussed with suitable topologies for applications such as fuel cells, photovoltaic, uninterruptible power supply (UPS), hybrid energy storage and load levelling systems identified.