Input Inductor Current Research Articles

An Integrated 50 V Boost Controller With Digitally-Assisted MPPT for Submodule PV Applications

This work introduces an integrated maximum power point tracking boost controller for photovoltaic submodule applications. The IC offers a wide input voltage range from 7 V to 24 V, whereas the output voltage is actively limited to 50 V. The presented design utilizes discrete, low-ohmic MOSFETs for the output stage and thus supports input power levels up to 144 W. The converter operates with peak-current-mode control at 300 kHz switching frequency in continuous conduction mode. During light load operation, the control transitions to direct input voltage sensing pulse-frequency-modulation (PFM) with input and output voltage dependent peak inductor current. Moreover, the low-side resistive current sense is explained in detail together with an inductor current replication circuit for precise high-side turn-off. The maximum power point tracker (MPPT) is based on an adjustable resistive sense element and a delta modulator and achieves 99.9 % tracking efficiency, omitting any need for a high resolution analog-to-digital converter (ADC). In addition, the series connection of multiple DC/DC converters is examined. The peak system efficiency measures 98.4 %. The application-specific integrated circuit (ASIC) is manufactured in an 0.18 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\mu$</tex-math></inline-formula> m HV-BCD process and occupies 6.25 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> of silicon area.

Design of double-integral sliding-mode controller for fourth-order double input DC - DC boost converter with a voltage multiplier cell

ABSTRACT A voltage multiplier cell (VMC)-integrated dual-input boost converter (DIBC) with an inductor at the two inputs for dual boost, and working at a duty cycle greater than 0.5 is a requirement for achieving a high voltage gain from low-voltage energy sources. The main focus of this work is to design a suitable control to effectuate the voltage regulation during input voltage and load disturbances, as well as to reduce the start-up transient. The pulse-width-modulation-based double-integral sliding-mode controller was investigated for desirable voltage regulation. Two input inductor current references are incorporated in the controller design to facilitate the decoupling between the interacting loops, which render the design complex with two sliding surfaces for each input inductor current. Also, a comparative analysis with dual-loop proportional-integral control for DIBC with single VMC is presented to highlight the robustness of the proposed controller. A converter model of 200 W is developed, and the controller is carried out using a field-programmable gate array. Under various disturbance scenarios, MATLAB simulation and experimental results clearly showed the satisfactory transient and steady-state output voltage regulation with the proposed controller.

Sliding-Mode Control of a Quadratic Buck Converter With Constant Power Load

This paper analyzes for the first time a two-loop sliding-mode control (SMC) of a high-order converter supplying a constant power load (CPL). The converter is a single-switch quadratic buck structure (QBC) interfacing a domestic 380 V DC bus to a CPL requiring a regulated voltage of 48 V DC. The converter is unstable in the absence of control and even after the insertion of an inner loop based on SMC of the input inductor current. The addition of an appropriate linear outer loop establishing the reference to the inner loop stabilizes the system and provides output voltage regulation. The regulated QBC shows a fast recovery of the output voltage with negligible overshoot in response to step-type changes of the output power or the input voltage. It is also shown that the implemented regulator for CPL supply can be used directly in the case of a constant current load (CCL) or a constant resistance load (CRL) resulting in similar performance to the CPL case. PSIM simulations and experimental results in a 400 W prototype are in good agreement with theoretical predictions.

Improved Adaptive Hamiltonian Control Law for Constant Power Load Stability Issue in DC Microgrid: Case Study for Multiphase Interleaved Fuel Cell Boost Converter

The cascaded connection of power converters in a DC microgrid may cause instabilities. Indeed, power converters operating as external loads exhibit constant power load (CPL) behaviors. In this study, the design of the feedback controller of a multi–cell interleaved fuel cell (FC) step–up power circuit is based on the adaptive Hamiltonian control law. It includes two integral terms to confirm that there is no steady-state error in the DC bus voltage, and to guarantee the current balancing of each input inductor current. The design confirms that the desired equilibrium point is (locally) asymptotically stable by using the Lyapunov stability proof. The control approach is validated via digital simulations and experimental tests performed with a 2500 W FC converter supplied by an FC/reformer size of 2500 W and 50 V.

A Novel Method for Parameter Identification of Fuel Cell Equivalent Circuit Model

In order to monitor the running state of fuel cell and prolong its service life, fault diagnosis technology has been widely researched. The fuel cell equivalent circuit model (ECM) can easily characterize the water content and membrane drying of the cells which has attracted the attention of scholars. Usually ECM is obtained by electrochemical impedance spectroscopy (EIS), and uses an electronic load for impedance excitation test, then achieves parameter identification through algorithms for fault diagnosis. This paper proposes a novel fuel cell ECM model parameter identification method by constructing a new combined network that the fuel cell ECM is included. It doesn’t require an electronic load to provide an excitation, meanwhile it relies on the DC/DC converter’s input voltage and inductor current, without voltage and current sensors on the fuel cell side. It uses the least square method to identify this new combined network’s parameter. This method reduces the cost of system components and achieves a good test performance.

CSI7: Novel Three-Phase Current-Source Inverter With Improved Reliability

Unlike voltage-source inverters (VSI), the power decoupling element in current-source inverters (CSI) is inductor. Inductor has a long lifetime and makes the CSI more reliable. However, the traditional CSIs suffer from open-circuit problem and dangerous voltage spikes are generated if the input inductor current is intermitted. Therefore, to avoid the voltage spikes, overlap-time should be inserted in the gate signals. But these intervals distort the output currents and reduce the current source utilization. To address these issues, a novel three-phase CSI is proposed in this article. The proposed inverter is originated from the conventional seven-switch CSI named CSI7 by adding only two small film capacitors. The film capacitors along with the pre-existing diodes of the CSI7 ensure that there is always a path for the inductor current, and thus the open-circuit issue is resolved. The elimination of open-circuit issue enhances the reliability and allows to minimize the overlap-time. This will improve the quality of output currents as well. Moreover, simulation and experimental results are provided at the output power of 950 W to verify the effectiveness of the proposed inverter.

MPPT oscillations minimization in PV system by controlling non-linear dynamics in SEPIC DC-DC converter

Solar PV power generation has achieved rapid growth in developing countries which has many merits such as absence of noise, longer life, no pollution, less time for installation, and ease of grid interface. A maximum power point tracking circuit (MPPT) consists of DC-DC power electronics converters that are used to improve the energy attainment from solar PV array. This paper presents a detailed analysis to control of chaos, a non-linear dynamic in SEPIC DC-DC converter interfaced solar PV system, to minimize the oscillations near to MPP. In SEPIC DC-DC converter, the input inductor current is continuous and capable of sweeping the whole I-V curve of a PV module from open circuit voltage (Voc) to short circuit current (Isc) operating points. To trace the true maximum power point and to nullify the oscillations near to MPP, the yield output voltage needs to ensure period-1 operation.

A double input-parallel-output-series hybrid switched-capacitor boost converter

A double input-parallel-output-series hybrid switched-capacitor boost (DIPOS-HSCB) converter is proposed which consists of two different kinds of input-parallel-output-series (IPOS) circuits, i.e., inner IPOS circuit and outer IPOS circuit. Two boost modules and one switched-capacitor network build an inner IPOS circuit based IPOS-HSCB converter and two IPOS-HSCB converters develop the outer IPOS circuit based DIPOS-HSCB converter. With the proposed DIPOS-HSCB converter, a high voltage-gain with low component stress and small input current ripple are achieved. Furthermore, an automatic current balancing function for all input inductor currents can be also achieved using a special carrier phase-shifted modulation scheme. A prototype rated at 200 V/120 W has been developed and the maximum efficiency of the proposed DIPOS-HSCB converter is 95% at 120 W. Both steady and dynamic results are presented to validate the effectiveness of the proposed DIPOS-HSCB converter.

Analysis and Design of Self-Oscillating Resonant Converters with Loss-Free Resistor Characteristics

A general approach for the analysis and design of self-oscillating resonant converters is presented in this paper, for a particular class of circuits in which the change of input voltage polarity is caused by the zero-crossings of the input inductor current. The key features of the method are an analytical description in the time-domain of a spiral that eventually converges into an ellipse, and a frequency–domain analysis that explains the behavior of the ellipse as a limit cycle. On a theoretical basis, this class of circuits behaves as loss-free resistors (LFR) because in steady-state the input inductor current is in phase with the first harmonic of the input voltage. The proposed analytical procedure predicts accurately the amplitude and frequency of the limit cycle and justifies the stability of its generation. This accuracy is reflected in the close agreement between the theoretical expressions and the corresponding simulated and measured waveforms. Third and fourth order resonant converters are designed following simple guidelines derived from the theoretical analysis.

Low power experimental prototype of a controlled three-phase inverter using D.S.P (TMS320F2812) for a hydraulic energy conversion chain application

This paper deals with a part implementation of the distributed generation chain system based on hydraulic power source operated in low power and controlled by DSP F2812. The experimental part of the chain includes a controlled two-level three-phase inverter connected, via an LC filter, to a load. This latter consists of a balanced three-phase resistive without neutral point joint, for this reason, the implementation requires fewer sensors as measuring devices. The proposed control strategy uses just two regulation loops; one of them is for the AC output voltages and the other one is for the input inductor currents of LC filter. This strategy was developed on Matlab-Simulink and implemented in eZdsp TMS320F2812 DSP board from spectrum digital. To confirm the efficiency and robustness of the chain part implementation, the experimental results using the implemented inverter was compared with a compact industrial module 7MBR15SA120 inverter mounting with the same control interface and measurement cards. The experimental waveforms comparison prove that there is a good match between the two practice prototypes, validate the theoretical study as well as the simulation results obtained and confirm the effectiveness of the proposed control strategy.

Low power experimental prototype of a controlled three-phase inverter using D.S.P (TMS320F2812) for a hydraulic energy conversion chain application

This paper deals with a part implementation of the distributed generation chain system based on hydraulic power source operated in low power and controlled by DSP F2812. The experimental part of the chain includes a controlled two-level three-phase inverter connected, via an LC filter, to a load. This latter consists of a balanced three-phase resistive without neutral point joint, for this reason, the implementation requires fewer sensors as measuring devices. The proposed control strategy uses just two regulation loops; one of them is for the AC output voltages and the other one is for the input inductor currents of LC filter. This strategy was developed on Matlab-Simulink and implemented in eZdsp TMS320F2812 DSP board from spectrum digital. To confirm the efficiency and robustness of the chain part implementation, the experimental results using the implemented inverter was compared with a compact industrial module 7MBR15SA120 inverter mounting with the same control interface and measurement cards. The experimental waveforms comparison prove that there is a good match between the two practice prototypes, validate the theoretical study as well as the simulation results obtained and confirm the effectiveness of the proposed control strategy.

An Input-Parallel–Output-Series Multilevel Boost Converter With a Uniform Voltage- Balance Control Strategy

An input-parallel–output-series multilevel boost converter is proposed in this paper. The theoretical analysis of this topology indicates that it has a high voltage gain, low component stress, small input current ripple, and automatic current balancing function for all input inductor currents. A uniform voltage-balance control strategy is subsequently proposed to address the capacitor voltage imbalance issue. The experimental study has been done to verify the correctness and feasibility of the proposed topology and the voltage-balance control strategy.

Integrated step‐up non‐isolated inverter with leakage current elimination for grid‐tied photovoltaic system

This study presents a non-isolated step-up inverter without leakage current for low-voltage renewable energy generation such as photovoltaic (PV) cells grid connection. From the structure of the proposed inverter, the negative terminal of the PV array is directly linked with the grid neutral, so the common mode voltage of the parasitic capacitance can be kept constant and the leakage current will not be generated in theory. Moreover, this transformerless inverter can produce an AC output voltage higher than the input DC voltage, which will reduce the sizes of the generation system. A switching modulation strategy carrier-based is analysed in detail when the input inductor current is operated in discontinuous conduction mode. The operation modes of the proposed inverter are also discussed, respectively, in positive and negative half line cycles. Finally, a digital experimental prototype is tested in the laboratory, and the experimental results are consistent with the theoretical analysis.

Power Frequency Harmonic Reduction and its Redistribution for Improved Filter Design in Current-Fed Switched Inverter

Due to the pulsating power at the inverter output terminals, the passive storage elements of the boost stage of the current-fed switched inverter (CFSI) contain a power frequency harmonic component (100 Hz), apart from dc and switching frequency components. In prior designs, the second harmonic component is suppressed by increasing the size of the input filter inductor and capacitor or by using additional circuits. This paper presents a complete characterization of a control-based approach to suppress the power frequency harmonic component in the input inductor current of a CFSI. It also presents a comprehensive characterization of the harmonic power redistribution. Using the proposed approach, it is demonstrated that the inductor value of a CFSI is reduced by 61% for the same peak-to-peak ripple. This leads to an improvement in the conversion ratio, efficiency, and power density of the overall converter. A SiC MOSFET-based CFSI with 75-kHz switching frequency is used to verify the proposed design philosophy.

A novel adaptive output feedback control for DC–DC boost converter using immersion and invariance observer

This paper presents a class of novel adaptive output feedback controller for DC–DC boost converter with global exponential stability. In addition, the control input constraint is considered in stability analysis. The proposed adaptive control scheme is constructed to estimate input voltage and inductor current using output voltage and control signal information. In order to estimate unavailable state and parameter, immersion and invariance technique is employed. The effectiveness of the proposed method is investigated via experimental test and the practical results endorse the efficiency of this adaptive controller.

Sliding mode current control of a NOCULL converter based on hysteresis modulation method in a wide range of operating conditions

This study presents a novel control scheme for voltage regulation of a negative output cascade ultra-lift Luo converter (NOCULLC). Due to the complicated high order model of the converter, its performance is degraded against large load variations, input voltage changes and parametric uncertainties. In order to enhance the converter behavior, a PI compensator and a sliding mode current controller are combined to control the fourth order NOCULLC worked in a wide range of operating conditions. Because of the non-minimum phase structure of the converter, the output voltage of the converter is indirectly regulated by enforcing the input inductor current to track its reference signal. The sliding mode current controller improves the dynamic and static performances of the converter by minimizing the inrush current of the input inductor of the converter and also, the PI controller eliminates the steady state error of the output voltage of the converter. The closed loop system stability is demonstrated by using sliding mode theory. Furthermore, this paper proposes a systematic procedure to compute the gains of the controller based on the stability constraints which guarantees robustness of the developed controller. The experimental results show the robustness and effectiveness of the proposed controller against parametric variations and uncertainties of the converter. Also, a comprehensive comparison of the general aspects of the properties between the developed method and other existed controllers is provided.

Nonisolated Two-Phase Interleaved LED Driver With Capacitive Current Sharing

In this paper, a nonisolated two-phase interleaved LED driver with capacitive current sharing is presented. In the proposed LED driver, the current sharing capacitor can be used to balance the input inductor currents and the LED currents. Furthermore, only one grounded LED string current is sensed and controlled. Moreover, under the interleaved control, the input current ripple can be reduced. Finally, the operating principles, analyses, and experimental results are provided to verify the effectiveness of the proposed LED driver.

Design of Fixed-Frequency Pulsewidth-Modulation-Based Sliding-Mode Controllers for the Quadratic Boost Converter

The steady-state regulation error in power converters that use the pulsewidth-modulation (PWM)-based sliding-mode (SM) controllers can be alleviated via the use of a double-integral term of the state variables in the sliding surface. However, this not only increases the order of the controller but may also require more variables like two currents in feedback. Ideally, the controller should be of a lower order to reduce the cost and for ease of implementation. The main objective of this brief is to design a fixed-frequency PWM-based SM controller for the quadratic boost converter using a reduced number of state variables. The SM controller used in this brief requires only one current for its implementation while enjoying the advantages offered by both fixed-frequency and double-integral approaches. Apart from this, two SM controllers using the input and output inductor currents of the converter are separately designed to find the most suitable inductor current for the controller design. Such study is especially required for the higher order converters wherein more than one inductor currents are available for feedback purposes. It is shown that the controller using the input inductor current is preferred over the controller using the output inductor current. Some simulation and experimental results are also provided to validate the theoretical conclusions.

Reduced order linear quadratic regulator controller for voltage multiplier cells integrated boost converter

The recent development in high gain DC–DC converters motivates its application on renewable energy systems with low output voltage such as photovoltaic cells resulting in the requirement of high voltage gain converters with improved static and dynamic characteristics. This study proposes an optimal reduced order linear quadratic regulator controller for a reduced order model of a voltage multiplier cell (VMC) integrated boost converter with two sensors for measuring the output voltage and the input inductor current. The dynamic performance of linear quadratic regulator controller over load, line and component perturbations are shown through extensive simulation studies on the reduced order model developed and the comparison is accomplished with conventional hysteresis current controller in order to disclose the best control technique in terms of dynamic response. The extensive analysis based on simulated results are verified exactly with a measured results in a 100 W prototype operating in continuous conduction mode VMC integrated boost converter controlled using DSPIC30F4011 processor. The control technique proposed computes error coefficients with less computation time, guarantees excellent system stability and offers improved dynamic characteristics for VMC integrated boost converter with reduced number of sensors.

Investigation of current‐mode controlled cascade boost converter systems: dynamics and stability issues

This study presents a comparative study of linear current-mode controllers for the regulation of a two-stage cascade boost converter having a single active switch. The current-mode controllers used in this study are designed using the input and output inductor currents of the converter. The objective of this study is to find the most suitable inductor current for feedback purposes. The analyses of the current-controlled systems are carried out using the state-space and frequency-response approaches. It is shown that the controller using the output inductor current is preferred over the controller using the input inductor current. Experimental and simulation results are also provided to validate the theoretical conclusions.