Peak Current Control Research Articles

The peak current control of permanent magnet brushless DC machine with asymmetric dual-three phases

The asymmetric dual-three phase BLDC motor has two sets of stator windings, in which the back EMF coefficients are different. This paper takes advantage of the asymmetric dual-three phase BLDC motor's structural features and proposes a new method for the accelerated problem of the BLDC motor operating in the high speed and the constant electromagnetic power. The dual phase windings of the BLDC motor are integrated into the circuit in the starting stage. When the motor's back EMF value is equal to the terminal voltage value, switch off a set of RST three phase windings whose back EMF coefficient is bigger and make the other set of stator winding UVW with smaller back EMF coefficient continue to operate under the rated power. As the motor rotor speed continues to increase, the electromagnetic torque remains unchanged. By using the peak current control strategy, we can deduce that the phase current of the UVW three-phase winding is twice the RST three-phase winding when the asymmetric dual-three phase BLDC motor operates at high speed and constant power.

A Commercial Low Cost, Highly Efficient UC3842 based High Brightness LED (HBLED) Lamp

The conventional lighting sources like incandescent and fluorescent lamps are replaced by High Brightness Light Emitting Diodes (HB-LEDs). In this paper, a HBLED driver using a Single Ended Primary Inductor Converter (SEPIC) with input Power Factor Correction (PFC) is presented. PFC is accomplished using a commercial inexpensive Peak Current Mode Controller (PCMC) IC UC3842 is newly combined with SEPIC converter. Extensive simulation results are carried out and a laboratory prototype to power 18W LED array from AC mains is implemented and the results are presented in detail.

Impedance‐based analysis of grid harmonic interactions between aggregated flyback micro‐inverters and the grid

Grid harmonic interactions due to aggregated flyback micro-inverters are investigated in this study. An impedance-based model based on the Norton model of flyback micro-inverters, which are with quasi-resonant peak-current control, is obtained by adopting the small-signal modelling approach. As a supplement to the existing output impedance modelling of string inverters with linear controllers, further study on micro-inverters under non-linear control is addressed in this study. Based on the derived impedance model, the admittance matrix of aggregated micro-inverters connected to the grid is formulated and the impedance-based analysis of the system stability is also presented. Consequently, by modelling the output admittance of the quasi-resonant peak-current controlled flyback micro-inverters, harmonic interactions with a distorted grid can be effectively forecasted. Results obtained from modelling, analysis and verifications have shown that the proposed method is a simple and valid way of dealing with the harmonic quasi-resonance problems.

Fuzzy peak current controlled integrated PFC convert-er with slope compensation

This propounded a novel method of design and implementation of a fuzzy peak current mode (PCM) controlled Buck Integrated Power Factor Correction (PFC) Converter with compensation ramp. It derives its advantages through low buck capacitor voltage and single control switch, which leads to reduced complex control and price. Sub-harmonic oscillations generates in peak current controller can be nullified by using ramp signal, there by improves the overall performance of the converter. The fuzzy controller (FLC) robust and effective than conventional linear controllers like P, PI, PID, hence in this work a (90 – 265V), 50Hz AC, 48V DC and 100 kHz frequency converter is implemented in MATLAB/Simulink software and results are presented. Results show that converter meets international regularity commission regulations.

Fuzzy LPCM controlled buck integrated PFC convert-er for Class-C&D appliances

This propounded a novel method of design and implementation of a fuzzy linear peak current mode (LPCM) controlled Buck Integrated Power Factor Correction (PFC) Converter. It derives its advantages through low buck capacitor voltage and single control switch, which leads to reduced complex control and price. Sub-harmonic oscillations generates in peak current controller can be nullified by using ramp signal, there by improves the overall performance of the converter. The fuzzy controller (FLC) robust and effective than conventional linear controllers like P, PI, PID, hence in this work a (90 – 265V), 50Hz AC, 48V DC and 100 kHz frequency converter is implemented in MATLAB/Simulink software and results are verified experimentally. Results show that converter meets international regularity commission regulations.

Analysis and Optimization of Variable-Frequency Soft-Switching Peak Current Mode Control Techniques for Microinverters

This paper presents a detailed power loss model for a microinverter with three different zero voltage switching boundary conduction mode (BCM) current modulation methods. The model is used to calculate the optimum peak current boundaries for each modulation method. Based on the power loss model, a dual-zone modulation method is proposed to further improve the microinverter efficiency. The proposed modulation method provides two main benefits: the addition of one more soft switching transition and low inductor peak current. The additional soft switching transition reduces switching losses by means of zero current switching. The lower peak current boundary reduces inductor rms current and conduction losses as well as allowing the output filter inductor to be smaller and more efficient. An improved BCM peak current control method was proposed and implemented on a microinverter prototype. The control circuit provides a highly accurate representation of the filter inductor current waveform and also provides galvanic isolation that simplifies control circuit design. The experimental results on a 400-W three-phase half-bridge microinverter validate the theoretical analysis of the power loss distribution and demonstrate that further improvement in efficiency can be achieved by using the proposed dual-zone modulation method.

Comparison of digital PWM control strategies for high‐power interleaved DC–DC converters

This paper evaluates three PWM digital control approaches to achieve the current sharing between phases in high power dual interleaved DC-DC converters. The implementation of a digital peak current, multi-sample averaged current and an enhanced single-sample averaged current control in a TMS320F28377D is described. Experimental results from a 60 kW, 75 kHz silicon carbide DC-DC converter are used to evaluate the steady-state and dynamic performance of the three control methods. Overall the best performance in terms of tracking and speed of response was achieved by the enhanced single-sample method. The multi-sampled technique is recommended for applications needing high tracking accuracy; however this is at the expense of the slowest dynamic response. The fastest dynamic response was achieved by the digital peak current control, but this is limited by poor noise immunity and instability for duty-ratios in the region of 0.5.

A Si/GaN-based Synchronous Boost DC-DC Converter with High Speed and High Accuracy Peak Current Control Unit

A Si/GaN-based Synchronous Boost DC-DC Converter with High Speed and High Accuracy Peak Current Control Unit

Analysis of a Time-Length Compensation Algorithm for Elimination of Subharmonic Oscillation and Application in a Digitally Controlled Primary-Side Regulation Flyback Converter

Subharmonic oscillation mostly happens in the continuous conduction modulation mode. Digital slope compensation and digital reposition compensation are two digital realized compensation methods to eliminate subharmonic oscillation. In the above two methods, a fast digital to analog converter (DAC) for slope voltage shaping or an analog to digital converter (ADC) for current sampling is required. In order to reduce the cost and simplify the compensation, a matrix analysis method is first put forward to analyze the generation mechanism of subharmonic oscillation in the primary-side regulation (PSR) flyback converter with peak current control. Based on the matrix analysis method, a simple time-length compensation algorithm is presented to eliminate subharmonic oscillation. Only the switch-on time is applied to compensate the primary peak current or the switching period of the next switching cycle. No subharmonic oscillation occurs and only a low-speed DAC is required. The cost is low as the fast DAC or ADC is removed. A 48-W PSR flyback converter is implemented to verify the above analysis. Experiments prove that the matrix analysis method is feasible, and the time-length compensation algorithm is effective to eliminate subharmonic oscillation. It can be promoted to eliminate subharmonic oscillation in different control methods and other power topologies.

Topology and Control Innovation for Auxiliary Power Supply in Dimmable LED Drivers

In this paper, a cost-effective architecture based on Flyback topology is proposed for both constant current (CC) output for LED drive and constant voltage (CV) output for auxiliary (AUX) supply. A novel nonlinear ramp-based control scheme is proposed to decouple the main CC power train from the CV AUX supply and avoid LED output flickering. Small signal modeling is presented to highlight the advantages of this control scheme over conventional peak current mode control. This scheme has been implemented successfully for a 40-W dimmable LED driver with a 12-V 3-W AUX supply.

An Efficient Buck/Buck-Boost Reconfigurable LED Driver Employing SIN2Reference

An efficient buck/buck-boost reconfigurable LED driver based on peak current control is introduced. The driver supports pulse-width modulation (PWM) and pulse-frequency modulation (PFM) operations. The use of a combination of rectified sin and sin2 functions in the reference is introduced for the purpose of improving the power factor (PF) and total harmonic distortion (THD) of buck and buck-boost converters. The optimal reference waveform shape for buck and buck/boost modes can be set externally. The design ensures that the peak of the inductor current maintains a constant level that is invariant for different ac line voltages. The LED driver has been implemented in a 130-nm CMOS process. PF and THD are improved when the proposed reference is employed, and the peak PF and lowest THD values are 0.995/0.983/0.996 and 7.8/6.2/3.5% for the buck (PWM), buck (PFM), and buck-boost (PFM) cases, respectively. The corresponding peak efficiency for the three cases is 88/92/91%, respectively.

Laboratory Course Modular Design for Learning Magnetic Components in Power Conversion Applications at Taipei Tech

The main theme of this paper is to present the laboratory course modular design for learning and hands-on magnetic components in power converters. The objective of the course is to give the students to model the converters, realize magnetic components and test the implemented converters via the hands-on work in order to improve practical skills of students under the insufficiency of regular course training. This designed course is based upon the modular concept of five modules in common use which include forward converter, flyback converter, push-pull converter, half-bridge converter and full-bridge converter. The controllers for these converter modules include voltage mode control and peak current mode control. The specifications for each converter module are the same, 48V/12V, 60W and 100 kHz of switching frequency. The designed modular curriculum has been applied to the Industrial Technology Research and Development Master (ITRDM) Program sponsored by the industry and government. And excellent acknowledgment from students is received for providing practical training and covering the wide range of magnetic components in power conversion applications.

A simplified controller and detailed dynamics of constant off-time peak current control

Abstract A fast and reliable current control is often the base of power electronic converters. The traditional constant frequency peak control is unstable above 50 % duty ratio. In contrast, the constant off-time peak current control (COTCC) is unconditionally stable and fast, so it is worth analyzing it. Another feature of the COTCC is that one can combine a current control together with a current protection. The time dynamics show a zero-transient response, even when the inductor changes in a wide range. It can also be modeled as a special transfer function for all frequencies. The article shows also that it can be implemented in a simple analog circuit using a wide temperature range IC, such as the LM2903, which is compatible with PV conversion and automotive temperature range. Experiments are done using a 3 kW step-up converter. A drawback is still that the principle does not easily fit in usual digital controllers up to now.

Fixed Switching Frequency Generalized Peak Current Control (GPCC) of DC–AC Converters

A fast and robust fixed switching frequency peak current controller for DC–AC converters is presented. The proposed method tends to mimic the switching behavior of pulse width modulation (PWM) techniques, so it features all the advantages of peak current controllers (such as simplicity, fast transient, and optimum dynamic response), with the superiority of fixed switching frequency and harmonic free output. The proposed method is a generalized approach that can be applied to different PWM schemes. The method is specifically elaborated for single-phase distributed generation applications, using various inverter topologies and mimicking different PWM schemes. Moreover, adaptive bands are proposed to provide active damping for the controller, to extend use of the proposed method for inverters with LCL output filters. Feasibility and performance of the controller is shown by means of simulations and experiments.

A Family of Single-Phase Hybrid Step-Down PFC Converters

Buck power factor correction (PFC) has attracted a lot of research interests for its low output voltage and high efficiency at low input condition. However, the traditional Buck PFC converter usually has low power factor (PF) and poor harmonic performance due to the inherent dead angle of the input current, especially at low input condition. To solve this problem, this paper proposes a family of hybrid PFC converter topologies combining the advantages of step-up PFC and step-down (Buck) PFC converters, which features low output voltage and continuous input current (high PF). The derivation methodology is presented in detail and two topologies are selected as typical examples to explore their performances. With the improved peak current control scheme, the two proposed converters can achieve high PF under universal input range, and their input current harmonics can easily meet the IEC61000-3-2 Class C limits. The optimal design considerations are presented and two 150–W prototypes are built to verify the theoretical analysis.

Buck Converter Control for Lead Acid Battery Charger using Peak Current Mode

DC-DC buck converters are used for battery chargers in many applications including renewable energy sources, inverters, electric vehicles and robots. In this paper a buck converter was built and its controller was developed using peak current control mode for current loop and phase lag for voltage loop. This paper proposes a formulation of plant disturbance due to load variation to obtain a nominal model based on small signal approach. The controller was derived analytically based on the nominal model. Experiment results show that the buck control system functions well in regulating the output voltage. During the start up without any load it can reduce input voltage from 300 V to output voltage of 133.9 V in 19.3 ms. The developed controller can maintain the output voltage under load variation from no load to sudden load of 0.26 A. When it was implemented to charge a lead acid battery string, constant current of 3.36 A was charged in the first 173 minutes followed by constant voltage of 134.7 V until the end of charging at time 483 minutes. Thus, the developed control system of lead acid battery charger works well.

Simulation of Flyback Converter with Peak Current Mode Control

Simulation of Flyback Converter with Peak Current Mode Control

Self‐compensation of DC–DC converters under peak current mode control

A new self-compensation technique is proposed for eliminating subharmonic oscillation and chaotic regimes in dc–dc switching converters under peak current mode control. The proposed method extracts a control signal from the error between the inductor current and a suitable reference and does not require an external signal generator as in the conventional ramp compensation scheme. The analytical expressions of the control domain using Filippov method are obtained. Simulation results show that the proposed technique can be implemented using standard analogue devices and can effectively eliminate subharmonic and chaotic oscillations and can ensure a stable operation for a wide range of the duty ratio.

Adaptive line voltage compensation scheme for a source‐driving controlled AC–DC LED driver

A primary-side controlled high-precision constant current AC-DC LED driver, based on source-driving control scheme, is designed for low-power LED-lighting applications in this study. The ratio between demagnetisation time T Demag and switching period T S and the primary peak current are remained constant by the proposed control IC, obtaining constant current output. Meanwhile, an adaptive line voltage compensation circuit, integrated in the primary peak current controller, is proposed based on source-driving control scheme. A compensation current proportional to line voltage is injected to the primary-side current sampling pin CS, thus making the turn-off bandgap reference of primary peak current under high-line voltage lower than that under low-line voltage. As a consequence, overshoot phenomena of primary peak current can be avoided, and the line regulation as well as the precision of output current can be improved. The proposed control IC has been fabricated in TSMC 0.35 μm 5 V/650 V CMOS/LDMOS process. Experimental results of a 5 W prototype show that the output current is kept stable at ~250 mA, and the line regulation is within ±0.5% in a wide range of universal-input ac voltage from 85 to 264 V, and that >80% efficiency is obtained under heavy LED loads.

Nonlinear dynamic behavior analysis of a DC/DC converter with an ultra-high frequency Z-source converter

Z-source converters have been used in new energy sources because of their advantages. These converters have attracted considerable attention under high-frequency conditions given their high power density and high conversion efficiency. However, the stability of a system of ultra-high frequency Z-source converters are likely to be affected because of the inappropriate selection of parameters or the interference of weak signals in the process of the system. These factors will render such converters unable to work properly. The chaotic bifurcation behavior of Z-source converters based on peak current control mode is analyzed in this study. A precise discrete iterative mapping model for such converters is established, and the regional stability of a system is determined based on the characteristic value of changes in the Jacobian matrix. Finally, the bifurcation and chaos phenomena in a high-frequency Z-source converter and the accuracy of the aforementioned analysis are verified via experiments. The conclusion drawn from this study does not only can provide a reference for the stable operation of ultra-high frequency Z-source converters, but also presents a theoretical basis for optimizing system parameters and improving control performance.