Closed-Loop Control Analysis of Interleaved Non-isolated Bidirectional DC-DC Converter

In this paper, average current mode control and peak current mode control methods are compared. A full-bridge converter has been chosen to test the controller performances. For the accurate design of controllers, some performance parameters are specified for the converter. The full-bridge converter output is used as 28V, 5.6kW. The desired maximum ripple at the output voltage is 200mV and the allowable ripple at the output current is 5A. Converter performance has been simulated with PSIM and discussed. Then, average current mode controller and peak current mode controller designs were made with this converter. The design of these methods has been done separately and has been simulated. Comparative results of these controllers were given and their pros and cons over each other were discussed. The things to be done to make the performance improvements of the controllers were mentioned and evaluated.

A current fed push pull converters cascaded with a buck pre-regulator is proposed. Voltage stress of the push pull switches is reduced by buck pre regulation. Pulse width modulation is done only to the switch in buck stage. Output voltage and the buck inductor current is controlled using average current mode control. The closed loop simulation of a 20W,100V,0.2A cascaded buck push pull converter with analog control circuit is done using PSIM. Closed loop simulation using digital control circuit is done by using a SIMCOUPLER module which couples power electronic circuit in PSIM and digital control circuit in MATLAB. Further, hardware implementation of digital controllers on two platforms is explained. Switching pulses are generated using digital circuit are fed to the converter switches and the converter is tested for the open loop operation.

A small signal analysis of DC-DC converters with Average Current Mode Control (ACMC) in Continuous Conduction Mode (CCM) is performed in a unified manner. Design-oriented equations are derived for all three types of DC-DC converters. These equations are such that they are expressed explicitly with converter circuit and operating parameters, making them easy to be directly applicable to practical design purposes. Experimental results of an ACMC Boost converter are given to validate the model prediction with good correlation.

Power quality disturbances, such as voltage sags and instantaneous power interruptions, are probably the most frequent and damaging phenomenon in industrial environments. Thus, to improve the sustainability of electrical equipment, the power supplies should tolerate these disturbances. The PFC boost converter operating in CCM is exhaustively used as a first-stage in the power supplies. The average current mode control is the most popular technique and implemented with analog or discrete-time controllers. However, at instantaneous power interruption, the inner controllers go to saturation mode. Consequently, the switching device (MOSFET), of the converter, might be permanently damage when the power returns after voltage interruption. Another current control technique is self-control. In this case, the dynamics controllers are different. Therefore, this paper investigates the operation of the converter at instantaneous power interruption. The average current mode control and self-control are analyzed. Protection strategy is implemented, by FPGA, in a single-phase CCM PFC boost converter. Simulation and experimental results confirm and validate the analysis.

<span lang="EN-US">This paper focuses on a single-switch buck-boost (SSBB) converter for light emitting diode (LED) lighting applications. The proposed LED driver with power factor correction (PFC) shows enhanced performance in terms of input power factor, efficiency and reduced voltage stress across the switch. The presented LED driver is operated in discontinuous conduction mode (DCM). The input PFC is carried out using average current mode control (ACMC) and the controller is optimized using artificial bee colony (ABC) algorithm. A hardware prototype of 50W LED driver with ACMC for PFC is implemented using a programmable interface circuit (PIC) microcontroller. The experimental results are presented and the performance is compared with a conventional buck boost LED driver. The proposed SSBB LED driver achieves an input power factor of 0.96 with an efficiency of 98%.</span>

In a battery electric vehicle (BEV), a High power density DC-DC converter must be used to reduce the size of the EV drive train. However, in high-power applications, inductors are often the largest component in dc-dc converters. The design of an inductor that uses with two different core materials, ferrite and sendust, is studied in this paper. This has been done for the 3kW DC-DC converter, the weight and size of the inductor have been compared. In comparison to the Ferrite core, it has been noted that the area product factor and weight of the Sendust core are both lowered by 22.0% and 23.0%, respectively. In addition, the generated computational delay from the DSP controller in the control loop has been taken into consideration for the design of the control algorithm in a selected microcontroller. The average current mode control (ACMC) has been implemented in the DSP microcontroller (TMS320F28335) including the delay. Also, a 3kW prototype is developed for experimental validation.

The purpose of this paper is to present a drastic improvement in the conventional ACC (average current mode control) of switching DC-DC power converters, consisting of the addition of an auxiliary controller in the control loop, besides the current and voltage regulators. The model-based auxiliary controller preserves the closed loop small-signal bandwidth (including loop gain crossover frequency and stability margins) of buck derived converters over a large range of variation of the power stage passive elements, the load and the line voltage. Moreover, this control scheme shows much better perturbation rejection properties (closed loop impedance and audiosusceptibility) than conventional ACC. From a control theory point of view, robust performance is achieved preserving stability. A 5 V-5 A, 50 kHz buck prototype operating from an input voltage ranging from 30 V to 15 V has been experimentally tested with different LC output filters, line and load conditions, including discontinuous conduction mode. Measurements of the small signal frequency response of the converter (loop gain, closed loop audiosusceptibility and output impedance) have been carried out, showing the improvement achieved by the proposed control scheme. The empirical large signal response of the converter, under load steps, is also shown in this paper in order to validate the concept.

The application of the average current mode control (ACMC) to a new type of very efficient post-regulator is studied in this paper. This post-regulator, called series-switching post-regulator (SSR), has been proposed to improve the dynamic response series-switching of power factor correctors (PFC), The post-regulator exhibits very high efficiency due to the fact that only a part of the total power undergoes a power conversion process. Using ACMC, the bandwidth of the post-regulator increases in relation to the one obtained when a conventional voltage-mode control (with or without feedforward) is used. As a result, the attenuation of the input voltage ripple (100-120 Hz) increases and, a lower bulk capacitor can be used to obtain a low voltage ripple at the output, which is extremely important when a battery is connected at the output. This is rather common in distributed power supply systems.

Comparative analysis of high voltage gain DC-DC converter topologies for photovoltaic systems

In this Paper, a new nonisolated single switch DC-DC converter with high voltage gain is proposed. The proposed converter introduced a hybrid switched capacitor technique for providing high voltage gain without high switch duty cycle. Also an auxiliary circuit has been applied to the proposed converter for providing soft switching condition. This circuit consists of two coupled inductor and one diode. Therefore converter switch is turned on under ZCS condition. The other advantages of the proposed converter are continuous input/output current, simple structure and PWM control. The principle of operation in continuous conduction mode (CCM) is analyzed. The proposed converter is simulated by PSPICE for confirming the results of theoretical analysis.

In this paper a novel L-impedance network based DC-DC converter integrated with capacitor-inductor-diode (CLD) cell is proposed. The L-impedance network based DC-DC converter is also named as switched inductor boost converter (SIBC) due to its high boosting nature of voltage. The inductors present in the SIBC are responsible for boosting nature and hence high voltage gain. The CLD cell consisting of two diodes, two capacitors and one inductor integrated with SIBC simultaneously increases the voltage gain as well as reduces the voltage stress across the active switch of DC-DC converter. So, the proposed SIBC-CLD has high voltage gain with reduced voltage stress in the active switch. The analysis is carried out through Matlab/Simulink in order to validate the theoretical aspects. Along with this a detail comparison has been made between the proposed SIBC–CLD with classical boost converter (CBC), classical boost converter with CLD (CBC-CLD) and classical switched inductor boost converter (SIBC).

Constant current sources are required to drive multiple color LED strings and the LED drivers that drive these LED lighting systems should provide multiple constant currents from a single dc source. In this paper, a single inductor multiple current output (SIMCO) converter that can provide N- independently controllable constant current outputs is reported. The average current in each color LED string is controlled independently by using hybrid average current mode control (HACMC). The HACMC combines the advantage of both average current mode control and charge control method. Traditional dimming approaches such as pulse width modulation and analog dimming can be incorporated in the proposed topology for color tunability and correlated color temperature control. The proposed approach uses a simple control logic, which is modular and can be scalable to N color LED lighting systems. The operation of the SIMCO converter with the HACMC is explained in detail. Simulation and experimental results with 48 V input and 12 W for N = 3 (RGB) color systems are presented.

Due to the full-wave AC–DC power conversion, second-order frequency oscillations of current and voltage are created in single-phase PV-grid-connected inverters. These oscillations propagate toward the input and adversely affect the PV power utilization ratio. Large power decoupling capacitors are the preliminary solution for coping with voltage ripples across PVs, and they decrease the lifetime of the overall system. This paper proposes the average current mode control (ACMC) of the input inductor in a DC–DC boost converter in a double-stage PV power conversion system. Through extensive explanations of the modeling and control of a DC–DC boost converter, it is shown that the ACMC reduces the propagation of the second-order frequency components (SOFCs) toward the input PV array. Two controllers—a proportional–integral controller and an integral single-lead controller—are considered to adjust the average value of the PV output current in a single-loop control structure. This control approach is simple to implement and exhibits high impedance to current oscillatory components, which, in turn, reduces the size of the required capacitance.

The use of the average current mode control in the two-input buck post-regulator is studied in this paper. Using this type of control, the bandwidth of the post-regulator increases in relation to the one obtained when a conventional voltage mode control (with or without feedforward) is used. As a result, the attenuation of the input voltage ripple (100-120 Hz) increases and, therefore, lower bulk capacitors can be used to obtain a very low voltage ripple in the output, which is very important when a battery is connected at the output. This is very common in distributed power supply systems.

In this paper a single stage offline LED driver that can drive N-color HB-LED strings is presented. The proposed converter provides multiple current outputs for N-Color HB-LED strings from an AC input. The current outputs are independently controllable to obtain the desired Correlated Color Temperature (CCT) and high Color Rendering Index (CRI) for dynamic lighting systems. Hybrid Average Current Mode Control (HACMC) approach is used to realize multiple current outputs. HACMC is a combination of both the Average Current Mode Control (ACMC) and non-linear charge control. The proposed converter also provides Power Factor Correction (PFC) to the AC input mains. Simulation and experimental results of a high CRI multi-color LED lighting system with 110V AC input are presented.