Performance characteristic of digital peak current mode control switching power supply

The boost type dc-dc converter is used for compensation of dc bus voltage in the dc power feeding system such as the renewable energy system. It should be operated stably to improve reliability of the system. The peak current mode control is applied to operate stably because the boost type dc-dc converter tends to be unstable. However, a peak value of reactor current cannot be captured in the digital controller. In this paper, a digital peak current mode control boost converter with conversion from current to frequency and using a frequency detector for a peak current detection in real time is presented. The effectiveness of the proposed method is verified by the comparison of the transient response under changing an input voltage between the conventional PID control and the proposed method.

Цифрові системи керування все частіше застосовуються у силовій електроніці, що обумовлено рядом переваг цифрового керування над аналоговим. У даній статті представлений коректор коефіцієнта потужності з адаптивним цифровим керуванням по піковому струму. Описано принцип керування по піковому струму та вказані переваги і недоліки даного методу. Наведена схема коректора з адаптивним цифровим керуванням. Проведене комп’ютерне моделювання підтвердило працездатність розробленого коректора. Бібл. 14, рис. 6.

This paper presents the principles and performance of peak current mode control applied to active clamp forward converter in comparison to the conventional voltage mode control. There is a clamp circuit comprising one auxiliary switch and one clamp capacitor, used in the forward converter to recycle the energy stored in the transformer. Due to presence of clamp circuit the active clamp forward converter with center tapped secondary exhibits fourth order power stage dynamics. When conventional voltage mode control is adapted, the forth order power stage dynamics imposes limitations on the closed loop performance of the converter. It is demonstrated that current mode control can be adapted to enhance the closed loop performance of active clamp forward converter. Different transfer functions are derived using state space average model. The peak current mode control is applied and simulation results are presented.

Aiming at the control strategy of digital switching power supply, BP neural network was added to optimize the control strategy based on the traditional peak current double closed-loop control strategy. Taking flyback converter as the research object, BP neural network is used to optimize the adjustment time and recovery speed of control, so as to improve the control performance and output performance of digital switching power supply system. Finally, MATLAB/Simulink simulation shows that the PID control with BP neural network makes the output voltage have faster response speed, smaller output ripple and stronger anti-interference ability compared with the traditional peak current double closed-loop PID control.

An adaptive slope compensation method for digital current mode control of dc-dc converters is proposed in this paper. The compensation slope is used for stabilizing the inner current loop in peak current mode control. In this method, the compensation slope is adapted with the variations in converter duty cycle. The adaptive slope compensation provides optimum controller operation in term of bandwidth over wide range of operating points. In this paper operation principle of the controller is discussed. The proposed controller is implemented in an FPGA to control a 100 W buck converter. The experimental results of measured loop-gain at different operating points are presented to validate the theoretical performance of the controller.

Utilities in the U.S. operate over 75,000 km (47,000 miles) of old cast-iron pipes for gas distribution. The bell-and-spigot joints tend to leak as these pipes age. Current repair practices are costly and highly disruptive. The objective of this program is to design, test and commercialize a robotic system capable of sealing multiple cast-iron bell and spigot joints from a single pipe entry point. The proposed system will perform repairs while the pipe remains in service by traveling through the pipe, cleaning each joint surface, and attaching a stainless-steel sleeve lined with an epoxy-impregnated felt across the joint. This approach will save considerable time and labor, avoid traffic disruption, and eliminate any requirement to interrupt service (which results in enormous expense to utilities). Technical challenges include: (1) repair sleeves must compensate for diametric variation and eccentricity of cast-iron pipes; (2) the assembly must travel long distances through pipes containing debris; (3) the pipe wall must be effectively cleaned in the immediate area of the joint to assure good bonding of the sleeve; and (4) an innovative bolt-on entry fitting is required to conduct repair operations on live mains. The development effort is divided into eleven tasks. Task 1--Program Management was previously completed. Two reports, one describing the program management plan and the other consisting of the technology assessment, were submitted to the DOE COR in the first quarter. Task 2--Establishment of Detailed Design Specifications and Task 3--Design and Fabricate Ratcheting Stainless-Steel Repair Sleeves are now well underway. First-quarter activities included conducting detailed analyses to determine the capabilities of coiled-tubing locomotion for entering and repairing gas mains and the first design iteration of the joint-sealing sleeve. The maximum horizontal reach of coiled tubing inside a pipeline before buckling prevents further access was calculated for a wide range of coiled-tubing string designs and pipe environments. Work conducted in the second quarter consisted of: (1) selecting a preferred pan/zoom/tilt camera; (2) initiating design of the digital control electronics and switching power supply for the control and operation of the in-pipe robotic modules; (3) continuing design of the repair sleeve and (4) initial testing of the wall-cleaning device. Most recently, activities in the third quarter included: (1) development of the system's pan/zoom/tilt camera control electronics and operating software, and implementing these in the surface and downhole modules and (2) further testing of the wall-cleaning elements used to clean the inside of the bell and spigot joints. Details of these activities are described in the body of the report along with a summary of events scheduled for the fourth quarter.

Switched-mode dc-dc converters are used to regulate dc voltages or currents at a certain desired level. Due to inherent switching action, currents and voltages in the circuit tend to oscillate around a given average value, as the output values present some ripple in steady-state condition. The low-frequency output current ripple (OCR) is a key parameter for design considerations when a light-emitting diode (LED) string load is considered. In order to compare their ripple magnitudes under distinct conditions regarding a buck-based LED driver operating in continuous conduction mode (CCM), this paper analyzes the conventional voltage mode control as well as the peak-current mode control in order to compare its OCR responses by the classical control theory. The methods are implemented considering the same control bandwidth so that a proper comparison can be established.

Digital current mode control finds wide spread application in point of load power converters in DC nano-grid because of its technical benefits. However, finite current-loop sampling effects introduce undesirable sub-harmonic oscillations. This paper presents an analytical framework to investigate such nonlinear phenomena in a digitally current mode controlled boost converter. Discrete-time models for multi-sampled current loops and uniform sample with compensating ramp are derived under continuous conduction mode. We show that the discrete-time maps for such systems are discontinuous in nature. While the error voltage using a proportional-integral controller stays within the zero-error-bin (ZEB), the reference current becomes constant and 1-D maps of the inner current-loop can be used for stability analysis. Uniform sampling may lead to chaos, period doubling or stable period-1 behavior depending on slope of the compensating ramp. Multi-sampled current loop imposes several borders in the discrete parameter space and may eventually lead to high periodic behavior. In a counter-based compensating ramp, staircase effects may lead to sub-harmonic oscillation. Such instability eventually brings the error voltage outside the ZEB and 2-D map models have to be used for further investigating the nonlinear phenomena. A boost converter prototype was made. Digital current mode control is realized using an FPGA device. Test results demonstrate close agreement with the analysis.

High accuracy and stability digital controlled power supply for magnet (DigCon-MPS) is developed at PLS. This power supply has three sections. The first section is digital controller including DSP&FPGA and precision ADC, the second section consists of IGBT driver and four quad IGBT switch, and the third section is LC output filter section. AC input voltage of power supply is 3-phase 21V, output current is 0 ∼ 150 A dc. Switching frequency of four quad IGBT switch is 25 kHz. The output current of power supply has very high accuracy of 100 μA step resolution at full range and the stability of +/-1.5 ppm for short term and +/-5 ppm for long term. This paper describes characteristics of filter and output current performance improvement after LC output filter at four quad digital power supplies.

This paper represents the digital current mode control for a multi-module bidirectional converter intended for battery charging/discharging applications. The digital current mode control is adapted to achieve equal current sharing and good dynamic performance. The predictive control is used for the digital current compensation and the direct method is adapted to the digital voltage compensation. The control parameters for the digital compensations are designed and fine-tuned using the SISO tool in MATLAB software. Theoretical predictions are confirmed with both MATLAB simulations and measurements on an experimental prototype converter.

This paper presents a novel 800W proto type digital P-I-D control switching power supply for the high voltage direct- current(HVDC) power feeding system The digital control circuit for HVDC power feeding system has some problems. Especially, the conversion time of A-D converter and the processing time of digital controller exert a bad influence upon the dynamic characteristics. In the proposed method, the calculation processes of P and I-D controls are parallel. The delay time of P control is less than that of I-D control. The results against the step change of load are discussed. As a result, it is revealed that the proposed circuit has the superior transient response.

The purpose of this paper is to present a digital control method which suppresses the delay-time for the switching power supply. Generally, there is the delay-time caused by the A/D conversion time and the calculation time in the digital control. It causes the worsening of the transient response and brings the instability of the system. The proposed method can suppress the delay-time and improve the transient response. Results show that the proposed method can improve the transient response compared with the conventional PID control method and existing proposed method. Thus, the proposed method can contribute to the improvement of the transient response effectively.

In this paper, we propose three advanced digital predictive current-mode control (DPCC) algorithms based on a simplified estimation method of duty cycle lost time for asymmetric half-bridge (AHB) LED constant-current driver. They are the digital predictive peak current mode control(DPPCC) algorithm based on leading-edge modulation, the digital predictive quasi-valley current mode control(DPqVCC) algorithm based on trailing-edge modulation, and the digital predictive quasi-average current mode control(DPqACC) algorithm based on double-edge modulation. Simulation and experimental results demonstrate that the three DPCC algorithms can effectively offset the effect of delay on digital control performance, which confirms the superiority of DPqACC. When the DPqACC is applied, the series-load-jump transition times are below 4.5 ms, the maximum load adjustment rate is 0.5%/ V, and the output current can be tuned continuously between 0.3 A and 4.5 A with the longest transition time of 1 ms. Moreover, the three DPCC algorithms are capable of compensating for low-frequency ripples due to the rapid regulation speed of the inner loop. With the electrolytic capacitance removed without additional ripple compensation, the maximum peak-to-peak value of the low-frequency secondary ripple is 0.1163 A (2.91%) when the input is 400 53sin(2ω <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><i>lin</i></sub> <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">t</i> ) V and the output is 4 A. This approach provides an excellent solution for the digital design of low-ripple AC-DC LED constant-current drivers without electrolytic capacitance.

With the continuous development of science and technology, online teaching has become an important form of teaching in all stages. In the application process of College English intensive reading online teaching interactive platform, there is a problem that the courseware upload time is too expensive. Therefore, a college English intensive reading online teaching interactive platform based on cloud service is designed. Hardware part: select the mode of automatic clock phase control to obtain analog power through digital power supply; Software part: Taking discourse as the basic unit, identify the characteristics of College English intensive reading course, set up online teaching interaction mode, reflect the multidimensional and extensibility of interactive content, and optimize the function of the platform by using cloud service. Experimental results: the cost of uploading courseware between the designed College English intensive reading online teaching interactive platform and the other two college English intensive reading online teaching interactive platforms is 7.812 s, 12.123 s and 12.127 s respectively, and the code rate is low. It shows that after fully integrating with cloud service technology, the use effect of College English intensive reading online teaching interactive platform is more prominent.

Laboratory courses form an integral part of electrical and electronic engineering curriculum necessary for equipping students with skills and ability to solve problems in real-world contexts. However, students often feel frustrated and demotivated while conducting certain experiments in laboratories due to hindrances like inability to debug circuits and lack of theoretical and practical knowledge. Students often come unprepared to the time-bound laboratory assignments with insufficient pre-reading and sometimes require continuous assistance from their instructors to perform the experiments in practical laboratory sessions. This paper presents an initial stage in developing heuristics for embedding intelligence into electronics engineering laboratory-based learning artefacts in a pervasive and ubiquitous computing scenario. Such artefacts can be tools and equipment like breadboards, voltmeter, digital power supply, etc., used in laboratories. An empirical study was conducted to understand the type of intelligence needed to be embedded into such objects in context of electrical and electronic engineering laboratories to improve learning experience of students by minimizing their cognitive load. Data was collated qualitatively from studies involving student feedbacks. Semi-structured interviews of undergraduate students and subject matter experts (SMEs) were carried out. Based on the study and data analysis, potential areas where interventions can be made have been identified and presented in this paper. Their potential to become a basis of formulating and embedding intelligence in the next stage is outlined.