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Energy Conversion Systems

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Nguyễn Gia Hào

Academic year: 2023

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A new bridgeless high voltage PFC boost converter with reduced conduction losses and low voltage stress. Key time domain waveforms of the proposed bridgeless high voltage boost PFC converter.

Figure 1. The conventional high step-up voltage gain PFC converter.
Figure 1. The conventional high step-up voltage gain PFC converter.

Theoretical Analysis

The voltage loading of the semiconductors in the proposed PFC bridgeless converter and its conventional bridge is shown in Table 1. The semiconductor conduction losses of the proposed PFC bridgeless converter and its conventional counterpart are presented in Figure 7.

Figure 5. The relationship of the voltage conversion ratio M and duty cycle D.
Figure 5. The relationship of the voltage conversion ratio M and duty cycle D.

Simulation Results

High efficiency DC-DC converter with high voltage gain and reduced switching voltage. IEEE Trans. A new non-isolated ultrahigh voltage boost DC-DC converter with low voltage stress.IEEE Trans.

Figure 13 displays the simulated input current harmonics compared with the IEC 61000-3-2 class D limits
Figure 13 displays the simulated input current harmonics compared with the IEC 61000-3-2 class D limits

Analysis of Nonlinear Dynamics of a Quadratic Boost Converter Used for Maximum Power Point Tracking

Introduction

The design of the DC step controller in the PV system is based on the linearized model at the appropriate operating point. However, this operating point is constantly changing in a PV system and the controller design is usually performed based on the lowest irradiance level [14].

Figure 1. A model of a PV-based DC microgrid equipped with high-voltage-gain MICs.
Figure 1. A model of a PV-based DC microgrid equipped with high-voltage-gain MICs.

System Description and its Mathematical Modeling 1. Operation Principle

In PV systems, the input voltage of the DC-DC converter is controlled, not the output voltage. A partial fraction decomposition of the transfer function defined in (17) leads to the following equivalent form suitable for conversion to a state space representation [34]:.

Figure 2. Two-stage grid connected PV system with a quadratic boost converter in the DC-DC stage.
Figure 2. Two-stage grid connected PV system with a quadratic boost converter in the DC-DC stage.

Small-Signal Model of the DC-DC Quadratic Boost Converter and Its Input Controller Design The design of the controller in a switching converter is conventionally based on a small-signal

In this case, according to Routh-Hurwitz criterion, all the poles of the quadratic boost converter are located in the left half of the complex plane. Figure 7 shows the crossover frequency and the phase margin of the model of the quadratic boost converter under the type II input port controller when the irradiance is varied in the range W/m2.

The Complete State-Space Switched Model of the Closed-Loop Quadratic Boost Regulator The complete model of the quadratic boost regulator is obtained by including the state variables

The complete state-space switch model of the closed-loop quadratic boost regulator The complete model of the quadratic boost regulator is obtained by including the state variables.

A Glimpse at the Solar PV System Behavior from Its Complete Mathematical Model

The last 100 samples are considered stable and the corresponding inductor current samples siL1(nT) are plotted against the bifurcation parameter. Note that the dynamics of the MPPT controller slightly changes the location of the bifurcation boundary, which improves stability on a fast time scale for larger irradiance values.

Figure 8. The startup response of the quadratic boost converter with a nonlinear PV source under MPPT control S = 500 W/m 2 , V M = 4 V
Figure 8. The startup response of the quadratic boost converter with a nonlinear PV source under MPPT control S = 500 W/m 2 , V M = 4 V

Stability Analysis of Periodic Orbits and Subharmonic Oscillation Boundary 1. Stability Analysis of Periodic Orbits

First, x(DT) and x(0) are calculated, and the stability of the system is checked by observing the location of the eigenvalues ​​of the monodromy matrix in the complex plane. Note that the critical value predicted by the eigenvalues ​​of the monodromy matrix is ​​very close to that predicted by the bifurcation diagram in Figure 11a.

Figure 12. Monodromy matrix eigenvalues’ loci for (a) the irradiance S ∈ ( 500, 1000 ) W/m 2 , V M = 4 V, Θ = 25 ◦ C, and (b) the ramp peak-to-peak amplitude V M ∈ ( 4, 5 ) V, S = 1000 W/m 2 , Θ = 25 ◦ C.
Figure 12. Monodromy matrix eigenvalues’ loci for (a) the irradiance S ∈ ( 500, 1000 ) W/m 2 , V M = 4 V, Θ = 25 ◦ C, and (b) the ramp peak-to-peak amplitude V M ∈ ( 4, 5 ) V, S = 1000 W/m 2 , Θ = 25 ◦ C.

Validation of the Theoretical Results by Using Numerical Simulations and Experimental Results

For example, for Vdcref =380 V, i.e. D =0.7824, the critical value of the ramp voltage amplitude from the theoretical expression was VM ≈4.8 V, while the one from the experimental measurements was VM ≈5.2 V. The waveforms of the inductor current are represented together with the in-harmonic bottom of both sides 1 and L2 unsteady. the ramp signal and the control voltage.

Figure 14. The experimental PV system response due to a change of step type in the irradiance level from 500 W/m 2 –1000 W/m 2 as in Figure 9
Figure 14. The experimental PV system response due to a change of step type in the irradiance level from 500 W/m 2 –1000 W/m 2 as in Figure 9

Conclusions

Predicting subharmonic oscillation of voltage-mode switching converters using a circuit-oriented geometric approach.IEEE Trans. Impedance matching in photovoltaic systems using cascade boost converters and sliding control.IEEE Trans.

Control of a DC-DC Buck Converter through Contraction Techniques

  • Mathematical Methods
  • The Buck Power Converter
  • Application to 2D-Case 1. Controller Design
  • Application to 3D-Case
  • Conclusions and Future Work

In Figure 2b,c we plot the orbit in (v,i) space during the steady state for the two references used in panel A) of the same figure. We also tested the system's ability to reject disturbances in both load and input voltage E.

Figure 1. Schematic diagram of a buck power converter.
Figure 1. Schematic diagram of a buck power converter.

Efficiency Optimization of a Variable Bus Voltage DC Microgrid

Description of the MG Studied

The MG studied is simulated in Simulink [20] and it is based on the MG described in [21]. The power references in all the MG's converters are therefore imposed by E-BCS, except when BVOC is implemented, that it modifies the BESS's converter power reference.

Figure 1. MG architecture. The MG is composed of a DC bus in which the following elements are connected: two Renewable Energy Sources (RES) (PV and WT), a controllable source (FC), a capacitors bank, a bidirectional grid-inverter (INV), a battery system (B
Figure 1. MG architecture. The MG is composed of a DC bus in which the following elements are connected: two Renewable Energy Sources (RES) (PV and WT), a controllable source (FC), a capacitors bank, a bidirectional grid-inverter (INV), a battery system (B

Analysis of the Energy Efficiency Curves of the DC-DC Converters

Figure 3(bI) is essentially the same graph, but with the efficiency curves of the bidirectional DC-DC converter BESS. In this curve, the efficiency of the LOAD converter also increases sharply from PLOAD= 0 kW to 1 kW.

Figure 3. Efficiency curves of LOAD’s and BESS’ converters at different switching frequencies (I) and bus voltages (II): (a) Quadratic buck converter interfacing with LOAD; (b) Bidirectional converter interfacing with BESS.
Figure 3. Efficiency curves of LOAD’s and BESS’ converters at different switching frequencies (I) and bus voltages (II): (a) Quadratic buck converter interfacing with LOAD; (b) Bidirectional converter interfacing with BESS.

Bus Voltage Optimization

To clarify how EMS calculates voptim, an example is given: the power loss equations for one of the DC-DC converters, which is one of the seven addends in equation (4). Pj(t), medj=PV, WT, FC, LOAD, EZ, INV, (8) where represents any instant, PC is the capacitor bank power, PBESS is the BESS power and∑jPjis the resultant power of the rest of the units of the MG. Equation (8) shows that the effect of the two storage elements, the BESS and the capacitor bank, is always equal to the sum of the powers arriving in the DC bus, but with opposite signs.

Switching Frequency Optimization

When the bus voltage drops below 260 V (rises above 360 ​​V), E-BCS activates FC (EZ), causing (consumes) excess power. Each time step, say in time, the local E-BCS controller of each inverter receives the measured value of vbus and SOC and determines the corresponding Pi from it. The BVOCBESS centralized controller (i.e. the BESS controller) receives all measured values ​​from the MG and calculates the value from it; a PI controller determines the PBESS from this reference.

Simulation Results

Furthermore, if the individual optimal bus voltage values ​​of the MG's converters coincide, the BVOCBESS performance may be more significant than in the MG studied in this paper. MG has been simulated with the implementation of both BVOCBESS (in BESS's converter) and OOSF (in all MG's converters) simultaneously. Again, the force in all units of the MG evolves very slowly compared to the evaluated ΔtOOSF.

Figure 5. Possible power flows in the MG. The green rectangle defines the system MG .
Figure 5. Possible power flows in the MG. The green rectangle defines the system MG .

Conclusions

Equations (A1)–(A37) are used to model the DC-DC converters in the simulation of the MG operation. In Proceedings of the IECON 2010–36th Annual Conference on IEEE Industrial Electronics Society, Glendale, AZ, USA, 7–10 November 2010;. In Proceedings of the 2017 IEEE International Conference on Energy Internet (ICEI), Beijing, China, 17-21 April 2017; pp.

Table A2. Equations utilized to model the converters’ power losses.
Table A2. Equations utilized to model the converters’ power losses.

Dynamic Analysis of a Permanent Magnet DC Motor Using a Buck Converter Controlled by ZAD-FPIC

Materials and Methods

Some sensors are used to measure the voltage, current and speed of the buck motor system. This model considers second order, where the state variables are the speed of the motor Wm(rad/s) and the armature current (A). The parasite resistancers=rs1+rMi is equal to the sum of the internal resistance of the .

Figure 2. Diagram of the buck converter connected to a DC motor.
Figure 2. Diagram of the buck converter connected to a DC motor.

Results and Analysis

Both simulation and experimental test show that the steady-state error is less than 1% for different values ​​of the parameter N. Figures 14 and 15 show the behavior of the ZAD-FPIC-controlled buck-motor system with two delay periods. Figure 16a shows the behavior of the system when instantaneous perturbations are generated in Vin as performed for the experimental test.

Figure 6. ZAD-FPIC controller simulation blocks.
Figure 6. ZAD-FPIC controller simulation blocks.

A Novel Step-Up Converter with an Ultrahigh Voltage Conversion Ratio

  • Novel Topology’s Structure and Its Basic Principle
  • Modeling and Theoretical Analysis
  • Comparisons among Different Topologies
  • Saber Simulations and Circuit Experiments
  • Conclusions

In addition, a fourth-order step-up converter with a voltage conversion ratio of (1−D)/(1−2D) was presented in [17] and a pulse width modulation (PWM) Z-source DC-DC converter with the same voltage conversion ratio was investigated in [18]. As described in Section 2, there are three stages of the proposed step-up converter in case 2. 1 A/div, blue) andvd (bottom: 10 V/div, green) for the average current state controlled proposed step-up converter in three cases.

Figure 1. Circuit schematic of the proposed step-up converter.
Figure 1. Circuit schematic of the proposed step-up converter.

Slope Compensation Design for a Peak Current-Mode Controlled Boost-Flyback Converter

Boost-Flyback Converter: Modeling and Control

A schematic diagram of the actual steady-state behavior of a Period-1 solution is shown in Figure 2. An overall schematic diagram of the boost-flyback converter with the proposed controller is shown in Figure 1. At the beginning of the period, the switch turns on and remains on until the switching state.

Table 1. States of the Period-1 orbit.
Table 1. States of the Period-1 orbit.

Slope Compensation Design

A complete stability analysis and salt matrix calculation for this system can be found in [51]. In Figure 5a,c, bifurcation diagrams varying the ramp slope are calculated while the desired output voltage remains fixed (see Figure 5a for Vre f =100 V and Figure 5c for Vre f =120 V). However, when we fix the ramp slope to Ar=2.2 A (the stability limit is close to two), the Period-1 orbit is stable for the full range of load resistance values ​​(see Figure 6b).

Table 2. Converter and experimental setup parameters.
Table 2. Converter and experimental setup parameters.

Conclusions

In Proceedings of the 2013 1st International Future Energy Electronics Conference (IFEEC), Tainan, Taiwan, 3–6 november 2013; pp. In Proceedings of the 2015 Online International Conference on Green Engineering and Technologies (IC-GET), Coimbatore, India, 27 november 2015; pp. In Proceedings of the 2017 IEEE Energy Conversion Congress and Exposition (ECCE), Cincinnati, OH, VS, 1–5 oktober 2017; p.p.

Figure A1. Flyback converter topologies.
Figure A1. Flyback converter topologies.

Passivity-Based Robust Output Voltage Tracking Control of DC/DC Boost Converter for Wind

DC/DC Boost Converter Nonlinear Dynamics

The input DC source voltage ofvin(t) comes from a wind power system consisting of a wind turbine, PMSG and rectifier, and the load current of iL(t) acts as an external disturbance. The true values ​​of inductance and capacitance are unknown, but their nominal values, denoted as L0 and C0, are known. The input DC source voltage ofvin(t) is time-varying but unknown except its initial value, i.e., vin, 0=vin (0) is known.

Output Voltage Tracking Controller Design

Sliding Mode Control of DC-DC Fly back Converter with Zero Steady-State Error.J. Direct voltage control of DC-DC boost converters using count-based predictive control model.IEEE Trans. Voltage Follow-up Control Design for DC-DC Boost Converter Via Total Sliding-Mode Technique.IEEE Trans.

Figure 2. Wind speed pattern from Weibull distribution-based wind model.
Figure 2. Wind speed pattern from Weibull distribution-based wind model.

Improvement of the Response Speed for Switched Reluctance Generation System Based on Modified

  • SRG Power Generation System 1. Principle of SRG
  • Capacitance Current Pulse Train Control 1. The Principle of Pulse Train Control
  • Optimization of Power Generation Efficiency of SRG
  • Experiment Model and Verification

Afterwards, the variation of the output voltage in the non-linear model can be expressed by;. It can be seen from Figure 13a, when the SRG runs in a steady state with a constant speedn= 1200 r/min, the ripple of V0 is large, which is up to 5 V. Figure 13. The experiment waveforms of the SRG. Through experiment verification, compared with the traditional SRG power generation system under PWM control, the CC-PT controlled SRG has the following advantages: a) The CC-PT controlled method can adjust the output voltage by using two or more sets of combinations of preset control pulses, which has the advantages of simple circuit structure and no compensation network.

Figure 1. Principles of SRG. (a) Profile of 8/6 SRG; (b) two phases of SRG.
Figure 1. Principles of SRG. (a) Profile of 8/6 SRG; (b) two phases of SRG.

Sliding-Mode Control of Distributed Maximum Power Point Tracking Converters Featuring

Mismatched Conditions and DMPPT

From Figure 2, however, it can be seen that the DC link is formed by the output capacitors of the DMPPT converters, which are connected in series. Therefore, the DC link voltage vdci is equal to the sum of the output capacitors voltages vb,1 and vb,2. This expression proved that the voltage applied to any one of the output capacitors depends on the power delivered by all the DMPPT converters.

Figure 4. Theoretical power production of the DMPPT system in Figure 2.
Figure 4. Theoretical power production of the DMPPT system in Figure 2.

Converter Model and Structure of the Control System

Equation (5) shows that in cases where the theoretical optimal operating conditions are outside the safe voltages, the new optimal operating voltages are at the border of the safe conditions, which provides the maximum power extraction from the PV panel connected to the inverter near the overvoltage condition. Especially in PV systems implemented with boost converters, SMCs have been adopted to improve the dynamic performance of the DC/DC converter in CMPPT systems [37,38]. In the next section, the stability conditions of the proposed SMC, the equivalent dynamics of the closed-loop system, the design of the SMC parameters, and the implementation of the proposed control system in both MPPTs (Φ='.

Figure 7. Concept of the proposed operation modes and sliding surfaces.
Figure 7. Concept of the proposed operation modes and sliding surfaces.

Analysis of the Proposed SMC

In light of the previous considerations, expressions (27) and (28) lead to the same constraint fork as given in expression (20). The equivalent dynamics corresponds to the closed-loop behavior of the system under the influence of SMC. The duty cycle d of the converter is defined as the average value of the signal within the switching period Tsw, as shown in equation (30).

Figure 9 shows the admittance of the BP585 PV panel, calculated using Equation (32), for the interest voltage range 16 V < v pv < 19 V
Figure 9 shows the admittance of the BP585 PV panel, calculated using Equation (32), for the interest voltage range 16 V < v pv < 19 V

Parameters Design of the Proposed SMC

The selection is performed using the Balance RatioBR defined in equation (41), which allows to compare the kpvan and λpv values ​​satisfying (40) in the entire range of interest of the PV access. Those constraints impose limits on the slew rate of the voltage reference vmppt provided by the P&O algorithm. For steady state operation of the SMC it is possible to assume vb=Vmax, hence the integral of (vb−Vmax)inΨbis constant.

Figure 10. k pv and λ pv values that fulfill restrictions in expression (40) for min  Y pv
Figure 10. k pv and λ pv values that fulfill restrictions in expression (40) for min Y pv

Implementation of the Proposed SMC

The implementation of SMC based on Ψbr requires the synthesis of sliding function and switching circuit. The figure also shows the digital implementation of the P&O algorithm and speed limiting, both of which work only in MPPT mode. This avoids the divergence of the P&O algorithm from the MPP area when the DMPPT converter is operating in protection mode.

Figure 17. Block diagram to synthesize Ψ b in Protection mode.
Figure 17. Block diagram to synthesize Ψ b in Protection mode.

Simulation Results

However, the simulation confirms that the SMC imposes the desired settling times=0.5 ms on the first DMPPT-U in the regulation of the output voltage vb,1 under Protection mode. In contrast, Figure 21 shows the simulation of the DMPPT system without enabling both the protection mode and slew rate limitation. Simulation of the DMPPT system without activating both the protection mode and the speed limit.

Figure 19. Simulation of the DMPPT system with the proposed control structure.
Figure 19. Simulation of the DMPPT system with the proposed control structure.

Experimental Implementation and Validation

This is also confirmed by signalPr, which is equal to 0 at the beginning of the experiment. The experiments confirm the correct protection of the second DMPPT converter provided by the proposed SMC. Therefore, the SMC of the second DMPPT-U follows the MPP voltage of the second PV panel by returning to MPPT mode.

Conclusions

Hình ảnh

Figure 1. The conventional high step-up voltage gain PFC converter.
Figure 9. The input current waveforms after the input LC filter: (a) v in = 110 V rms ; (b) v in = 220 V rms .
Figure 11. The simulated PF and THD of the proposed bridgeless high step-up gain PFC converter.
Figure 2. Two-stage grid connected PV system with a quadratic boost converter in the DC-DC stage.
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