Bidirectional forward-flyback dc-dc converter

The polarities are the same as in the input. A step-up circuit is used to generate a higher voltage than the input voltage. It is called as a boost. The polarities are same as in the input. In Buck-Boost Converter , the output voltage can be increased or decreased than the input voltage. It works to either boosting or bucking the voltage. The common usage of this converter is to reverse the polarity.

Cuk: This type of converter is similar to the Buck-Boost converter. The difference is its name, named after Slobodan Cuk, the man who created it. Charge Pump: This converter is used to step the voltage up or down in applications that have low power.

These converters have a separation between input and output terminals. They have high isolation voltage properties. They can block the noise and interference. This allows them to produce a cleaner DC source. They are categorized into two types. This converter works similar to the buck-boost converter of the non-isolating category. Home Explore Login Signup. Successfully reported this slideshow. We use your LinkedIn profile and activity data to personalize ads and to show you more relevant ads.

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Need an account? Click here to sign up. Download Free PDF. Mohd Hasan Ali. A short summary of this paper. Download Download PDF. Translate PDF. To overcome these drawbacks, this paper proposes a new, nonisolated, DC-DC converter for the bidirectional power flow of battery energy storage applications in DC and hybrid microgrids HMGs.

The proposed converter uses two back-to-back Boost converters with two battery voltage levels, which eliminates step-down operation to obtain symmetric gains and dynamics in both directions. In discharge mode, two battery sections are in parallel connection at a voltage level lower than the grid voltage.

In charge mode, two battery sections are in series connection at a voltage level higher than the grid voltage. The results show that the proposed converter has promising performance compared to that of the conventional type. Moreover, the novel converter adds no complexity to the control system and does not incur considerable power loss or capital cost.

Keywords: battery energy storage system; bidirectional DC-DC converter; dynamic performance; hybrid microgrid; renewable energy sources 1. Introduction The popularity of DC microgrids and their operation along with AC microgrids is increasing due to the elevated level of DC power renewable generations and ubiquitous DC loads.

HMGs, particularly in islanded operation, are prone to instability and power fluctuations due to the intermittent nature of renewable energy sources RES and the stochastic behavior of the loads. It is imperative to regulate system oscillations with faster dynamics and reliable controllers. Electronics , 9, ; doi Figure 1 shows Boost converter in step-up mode, with two controllable semiconductor switches.

Figure 1 shows the the conventional, nonisolated conventional, nonisolated BDC BDC with with some some drawbacks, drawbacks, as as noted noted below. Figure Conventional bidirectional 1. This asymmetry gain. This asymmetry originates originates from the from the different different circuit circuit structures structures inin both both modes. Therefore, the modes. Therefore, the converter converter should should work work with with different duty ratios in both modes, resulting in an asymmetric and relatively slow control different duty ratios in both modes, resulting in an asymmetric and relatively slow control response during response during power power flow flow direction direction changeover.

This This issue issue is is addressed addressed to to some some extent extent by by selecting a small enough battery voltage compared to the grid voltage, resulting selecting a small enough battery voltage compared to the grid voltage, resulting in a high voltagein a high voltage difference between difference between two two sides; sides; otherwise, otherwise, the the Buck Buck operation operation would would notnot be be as aseffective.

However, However, this potential this potential difference difference results results in in high high current current peaks peaks inin both both switching switching operations, operations, leading leading to to high current ripples, particularly in heavy load levels. This issue is usually tackled high current ripples, particularly in heavy load levels. This issue is usually tackled by selecting by selecting a large inductor, thereby incurring a higher capital a large inductor, thereby incurring a higher capital cost.

Other issues Other issues regarding regarding conventional conventional BDC BDC are are reported reported in in the the literature literature [13,14] [13,14] from from different different viewpoints, although this paper does not aim to address them.

Previous viewpoints, although this paper does not aim to address them. Previous studies proposed several studies proposed several isolated and isolated and nonisolated nonisolated bidirectional bidirectional topologies topologies to to improve improve dynamic dynamic performance, performance, gain, gain, efficiency, efficiency, and operability and operability ofof BDCs BDCs for for energy energy storage storage and and renewable renewable applications.

Nonisolated,Nonisolated, resonant-type,resonant-type, bidirectional bidirectional converters converters were weretoproposed proposed increase to theincrease overall the overall voltage gainvoltage usinggain usinginductors coupled coupled inductors and clamping and clamping capacitor capacitor circuits operating in zero-voltage-switching ZVS conditions [15,16]. An isolated, three-port, An isolated, three-port, inductor-capacitor-inductor LCL -resonant inductor-capacitor-inductor LCL -resonantconverter converter operating operating in in zero-current-switching zero-current-switching ZCS ZCS condition was also implemented in [17] with the capability of integrating photovoltaic condition was also implemented in [17] with the capability of integrating photovoltaic PV source to PV source to energy storage.

However, However,these these resonant resonant converters converters addadd complexity complexity andtocost and cost bothtopower both power and and control controland stages stages and incur moreincurlossmore due loss due to additional to additional circuit components. In addition, In no addition, controlno control strategies strategies were were presented presented that symmetrically that symmetrically worked forworked both modesfor both modes in bidirectional in bidirectional applications.

A relatively A high voltage relatively high voltage gain gain was was achieved achieved for for step-down step-down operation operation using using aa switched-capacitor switched-capacitor cell augmented to a conventional half-bridge [18]. However, this configuration was cell augmented to a conventional half-bridge [18]. However, this configuration was anan improved improved version of the half-bridge converter, making only a slight improvement only version of the half-bridge converter, making only a slight improvement only in voltage gain at the cost in voltage gain at the of cost of additional additional components components with adesign with a control control designasymmetrically working working asymmetrically for both for both modes.

The modes. The nonisolated nonisolated converter inconverter [13] and its in improved [13] and itshigh-efficiency improved high-efficiency topology intopology in [19]soft-switching [19] provided provided soft-switching operation, operation, employing a ideal transformer and pulse-frequency employing a ideal transformer and pulse-frequency modulation to accommodate modulation to accommodate load load variation variation and reducedandswitching reduced loss switching loss andhigh and to achieve to achieve efficiency.

Electronics , 9, 3 of 21 a single loop Proportional-Integral PI controller that worked for both modes, with applications in residential energy storage systems. Research work in [20] proposed a nonisolated BDC employing two conventional Boost converters to achieve the squared value of voltage gain of that of the conventional BDC.

Although functional improvements in voltage gain, switching operation, and converter efficiency were obtained in the mentioned literature, the problem of bidirectional asymmetry in voltage gain and control scheme persists.

Several noteworthy features of the proposed converter are as follows: i It employs two Boost converters in back-to-back topology and has a minimum additional component compared with other proposed converter configurations.

Since there is no Buck operation and the battery voltage can be raised to higher levels, the converter inductors have less inductance and current capacity due to the reduced battery current. Proposed bidirectional DC-DC converter. Figure 2. Table 1 presents a summarized comparison of the salient features of the proposed BDC in this paper and other BDCs submitted in previously discussed research Main works.

Hybrid microgrid under the study. The HMG 4. Section given in4. Section 4. Electronics , 9, 4 of 21 Table Table1. Comparison Table 1. Comparison conventional, Table and proposed, between other and 1. Table 1. Discharge counted. Body are capacitors are considered. Body considered. Proposed not counted. Figure 3. Principle of Operation 2.

Principle of Operation The proposed converter is composed of two Boost converters in a back-to-back configuration. Therefore, there is only The proposed step-up converter mode in both is composed directions. Bidirectional flyback DC-DC converter for hybrid electric vehicle: Utility, working and PSPICE computer model Abstract: There is a trend in the automotive industry to replace more engine driven mechanical and hydraulic loads with electrical loads, due to higher efficiency, safety requirement and driver's comfort.

This paper first introduces the advance power system for hybrid electric vehicles HEVs. The role of bidirectional dc-dc converter in the architecture is, then, explained.