Duty Ratio Predictive Control Scheme for Digital Control of DC-DC Switching Converters

Pengju Sun,Luowei Zhou 전력전자학회 2011 JOURNAL OF POWER ELECTRONICS Vol.11 No.2

The control loop time delay caused by sampling, the zero-order-holder effect and calculations is inevitable in the digital control of dc-dc switching converters. The time delay will limit the bandwidth of the control loop and therefore degrade the transient performance of digital systems. In this paper, the quantization time delay effects with different time delay values based on a generic second-order system are analyzed. The conclusion that the bandwidth of digital control is reduced by about 20% with a one cycle delay and by 50% with two cycles of delay in comparison with no time delay is obtained. To compensate the time delay and to increase the control loop bandwidth, a duty ratio predictive control scheme based on linear extrapolation is proposed. The compensation effect and a comparison of the load variation transient response characteristics with analogy control, conventional digital control and duty ratio predictive control with different time delay values are performed on a point-of-load Buck converter by simulations and experiments. It is shown that, using the proposed technique, the control loop bandwidth can be increased by 50% for a one cycle delay and 48.2% for two cycles of delay when compared to conventional digital control. Simulations and experimental results prove the validity of the conclusion of the quantization effects of the time delay and the proposed control scheme.

Duty Ratio Predictive Control Scheme for Digital Control of DC-DC Switching Converters

Sun, Pengju,Zhou, Luowei The Korean Institute of Power Electronics 2011 JOURNAL OF POWER ELECTRONICS Vol.11 No.2

The control loop time delay caused by sampling, the zero-order-holder effect and calculations is inevitable in the digital control of dc-dc switching converters. The time delay will limit the bandwidth of the control loop and therefore degrade the transient performance of digital systems. In this paper, the quantization time delay effects with different time delay values based on a generic second-order system are analyzed. The conclusion that the bandwidth of digital control is reduced by about 20% with a one cycle delay and by 50% with two cycles of delay in comparison with no time delay is obtained. To compensate the time delay and to increase the control loop bandwidth, a duty ratio predictive control scheme based on linear extrapolation is proposed. The compensation effect and a comparison of the load variation transient response characteristics with analogy control, conventional digital control and duty ratio predictive control with different time delay values are performed on a point-of-load Buck converter by simulations and experiments. It is shown that, using the proposed technique, the control loop bandwidth can be increased by 50% for a one cycle delay and 48.2% for two cycles of delay when compared to conventional digital control. Simulations and experimental results prove the validity of the conclusion of the quantization effects of the time delay and the proposed control scheme.

An Active Clamp High Step-Up Boost Converter with a Coupled Inductor

Quanming Luo,Yang Zhang,Pengju Sun,Luowei Zhou 전력전자학회 2015 JOURNAL OF POWER ELECTRONICS Vol.15 No.1

An active clamp high step-up boost converter with a coupled inductor is proposed in this paper. In the proposed strategy, a coupled inductor is adopted to achieve a high voltage gain. The clamp circuit is included to achieve the zero-voltage-switching (ZVS) condition for both the main and clamp switches. A rectifier composed of a capacitor and a diode is added to reduce the voltage stress of the output rectifier diode. As a result, diodes with a low reverse-recovery time and forward voltage-drop can be utilized. Since the voltage stresses of the main and clamp switches are far below the output voltage, low-voltage-rated MOSFETs can be adopted to reduce conduction losses. Moreover, the reverse-recovery losses of the diodes are reduced due to the inherent leakage inductance of the coupled inductor. Therefore, high efficiency can be expected. Firstly, the derivation of the proposed converter is given and the operation analysis is described. Then, a steady-state performance analysis of the proposed converter is analyzed in detail. Finally, a 250 W prototype is built to verify the analysis. The measured maximum efficiency of the prototype is 95%.

An Active Clamp High Step-Up Boost Converter with a Coupled Inductor

Luo, Quanming,Zhang, Yang,Sun, Pengju,Zhou, Luowei The Korean Institute of Power Electronics 2015 JOURNAL OF POWER ELECTRONICS Vol.15 No.1

An active clamp high step-up boost converter with a coupled inductor is proposed in this paper. In the proposed strategy, a coupled inductor is adopted to achieve a high voltage gain. The clamp circuit is included to achieve the zero-voltage-switching (ZVS) condition for both the main and clamp switches. A rectifier composed of a capacitor and a diode is added to reduce the voltage stress of the output rectifier diode. As a result, diodes with a low reverse-recovery time and forward voltage-drop can be utilized. Since the voltage stresses of the main and clamp switches are far below the output voltage, low-voltage-rated MOSFETs can be adopted to reduce conduction losses. Moreover, the reverse-recovery losses of the diodes are reduced due to the inherent leakage inductance of the coupled inductor. Therefore, high efficiency can be expected. Firstly, the derivation of the proposed converter is given and the operation analysis is described. Then, a steady-state performance analysis of the proposed converter is analyzed in detail. Finally, a 250 W prototype is built to verify the analysis. The measured maximum efficiency of the prototype is 95%.

Junction Temperature Prediction of IGBT Power Module Based on BP Neural Network

Junke Wu,Luowei Zhou,Xiong Du,Pengju Sun 대한전기학회 2014 Journal of Electrical Engineering & Technology Vol.9 No.3

In this paper, the artificial neural network is used to predict the junction temperature of the IGBT power module, by measuring the temperature sensitive electrical parameters (TSEP) of the module. An experiment circuit is built to measure saturation voltage drop and collector current under different temperature. In order to solve the nonlinear problem of TSEP approach as a junction temperature evaluation method, a Back Propagation (BP) neural network prediction model is established by using the Matlab. With the advantages of non-contact, high sensitivity, and without package open, the proposed method is also potentially promising for on-line junction temperature measurement. The Matlab simulation results show that BP neural network gives a more accuracy results, compared with the method of polynomial fitting.

Analysis and Design of Function Decoupling High Voltage Gain DC/DC Converter

Wei, Yuqi,Luo, Quanming,Lv, Xingyu,Sun, Pengju,Du, Xiong The Korean Institute of Power Electronics 2019 JOURNAL OF POWER ELECTRONICS Vol.19 No.2

Traditional boost converters have difficulty realizing high efficiency and high voltage gain conversion due to 1) extremely large duty cycles, 2) high voltage and current stresses on devices, and 3) low conversion efficiency. Therefore, a function decoupling high voltage gain DC/DC converter composed of a DC transformer (DCX) and an auxiliary converter is proposed. The role of DCX is to realize fixed gain conversion with high efficiency, whereas the role of the auxiliary converter is to regulate the output voltage. In this study, different forms of combined high voltage gain converters are compared and analyzed, and a structure is selected for the function decoupling high voltage gain converter. Then, topologies and control strategies for the DCX and auxiliary converter are discussed. On the basis of the discussion, an optimal design method for circuit parameters is proposed, and design procedures for the DCX are described in detail. Finally, a 400 W experimental prototype based on the proposed optimal design method is built to verify the accuracy of the theoretical analysis. The measured maximum conversion efficiency at rated power is 95.56%.

Analysis and Design of Function Decoupling High Voltage Gain DC/DC Converter

Yuqi Wei,Quanming Luo,Xingyu Lv,Pengju Sun,Xiong Du 전력전자학회 2019 JOURNAL OF POWER ELECTRONICS Vol.19 No.2

Traditional boost converters have difficulty realizing high efficiency and high voltage gain conversion due to 1) extremely large duty cycles, 2) high voltage and current stresses on devices, and 3) low conversion efficiency. Therefore, a function decoupling high voltage gain DC/DC converter composed of a DC transformer (DCX) and an auxiliary converter is proposed. The role of DCX is to realize fixed gain conversion with high efficiency, whereas the role of the auxiliary converter is to regulate the output voltage. In this study, different forms of combined high voltage gain converters are compared and analyzed, and a structure is selected for the function decoupling high voltage gain converter. Then, topologies and control strategies for the DCX and auxiliary converter are discussed. On the basis of the discussion, an optimal design method for circuit parameters is proposed, and design procedures for the DCX are described in detail. Finally, a 400 W experimental prototype based on the proposed optimal design method is built to verify the accuracy of the theoretical analysis. The measured maximum conversion efficiency at rated power is 95.56%.

Junction Temperature Prediction of IGBT Power Module Based on BP Neural Network

Wu, Junke,Zhou, Luowei,Du, Xiong,Sun, Pengju The Korean Institute of Electrical Engineers 2014 Journal of Electrical Engineering & Technology Vol.9 No.3

In this paper, the artificial neural network is used to predict the junction temperature of the IGBT power module, by measuring the temperature sensitive electrical parameters (TSEP) of the module. An experiment circuit is built to measure saturation voltage drop and collector current under different temperature. In order to solve the nonlinear problem of TSEP approach as a junction temperature evaluation method, a Back Propagation (BP) neural network prediction model is established by using the Matlab. With the advantages of non-contact, high sensitivity, and without package open, the proposed method is also potentially promising for on-line junction temperature measurement. The Matlab simulation results show that BP neural network gives a more accuracy results, compared with the method of polynomial fitting.

LCL-T resonant network-based modular multi-channel constant-current LED driver analysis and design

He, Qingqing,Luo, Quanming,Huang, Jian,Cao, Chi,Sun, Pengju,Du, Xiong The Korean Institute of Power Electronics 2020 JOURNAL OF POWER ELECTRONICS Vol.20 No.6

Multiple output LED drivers are necessary to achieve better performance and higher reliability in street lighting, tunnel lighting and LCD background lighting applications. Based on LCL-T constant-current characteristics, a modular multiple output LED driver is proposed in this paper. The LCL-T rectifiers are connected to the same voltage bus and work like current sources. However, since there are much higher voltage harmonics in the AC square bus voltage, it is very important to quantitatively analyze how these harmonics influence the precision of the output currents. In addition, all of the switches can achieve Zero Voltage Switching (ZVS) by proper design of the LCL-T network. Finally, a 200-W prototype with five channels is established with an efficiency of 92.25%.

Compressive Strength, Hydration and Pore Structure of Alkali-Activated Slag Mortars Integrating with Recycled Concrete Powder as Binders

Hao Wang,Liang Wang,Wenfeng Shen,Ke Cao,Lei Sun,Pengju Wang,Liyun Cui 대한토목학회 2022 KSCE JOURNAL OF CIVIL ENGINEERING Vol.26 No.2

Recycled concrete powder (RCP) recycling can reduce the consumption of natural resources, which has been highlighted as an ecofriendly and sustainable approach. The alkali-activated slag (AAS) offers notable prospects for replacing conventional Portland cement binders. In this study, we partially replaced granulated blast furnace slag (GBFS) with RCP to prepare the AAS mortars. We evaluated the effect of RCP replacement levels and fineness levels on compressive strength, early hydration process, and pore structure pertaining to AAS mortars with RCP (RCP-AAS mortars). According to the experimental results, using 10 – 30% RCP inside AAS mortars enhanced the compressive strength at 1 day, and the improvement was obvious with increasing RCP fineness. The RCP delayed the early-age hydration of the GBFS, decreased the content of hydration products and increased the total porosity. Therefore, it exhibited a negative effect on 28-day compressive strength. These drawbacks of RCP, however, could be modified by increasing its fineness.