New high power, high performance power converter systems

A new, high performance, low cost power converter system architecture is proposed. The system consists of a main converter and a multifunctional load conditioner. The main converter deals with most of the power flow running at a low switching frequency. The load conditioner is designed at a much lower power level running at a high-switching frequency. The load conditioner can (1) act like a current source and inject harmonic currents required by the load; (2) act like an active resistor to provide damping to the main converter; and (3) for three-phase inverters, decouple the coupling sources in the main inverter model in the rotating coordinates to make the control loop design for the main inverter much easier. The concept has been proved by simulation and experimental results on a 150 kW high performance three-phase utility power supply prototype. The proposed system configuration can be used in high power DC-DC converters, inverters, PFC and UPS applications     

A low frequency AC to high frequency AC inverter with build-in power factor correction and soft-switching

This paper presents a full bridge AC-AC inverter for high frequency power distribution system with power factor correction stage controlled by a unified controller. The proposed inverter has the following features: 1) load independent output voltage with constant frequency and very low total harmonic distortion (THD); 2) soft switching of the full bridge switches for a wide range of input voltage and load conditions; 3) low DC bus voltage; 4) simple control and cost effectiveness for the power factor correction stage. Operating principles and performance characteristics are presented, and guidance to design the converter is given. Experimental results of a 90-265V/sub ac/ input, 30 V/sub ac/ output at 100 kHz, 250 W laboratory prototype are given to verify the theoretical and simulation results. The proposed ac-ac inverter is attractive for low power (up to 250 W) high frequency applications.     

一种宽输入电压范围软开关电流型DC/DC转换器

针对太阳能光伏及燃料电池等领域电源需要较宽输入电压范围的需求,提出一种通用的具有较宽输入电压范围的软开关电流型DC/DC转换器。该转换器采用了固定频率混合调制设计,可以在所有工作条件下实现半导体器件的软开关工作,并采用电流馈电技术以便适用于低电压高电流的电源。相较于传统转换器,该转换器更为通用,能够实现零电压开关和零电流开关,并且能够在输入电压和负载变化出现较大变化时控制输出电压。实验结果显示,在20-60V输入电压范围内且负载出现变化时,该转换器均表现出良好的性能。     

An automatic load-adaptive switching frequency selection technique for improving the light-load efficiency of a buck converter

A load-adaptive automatic switching frequency selection scheme is proposed to improve the power efficiency of a switching buck converter at light load condition. The buck converter operates in the continuous-conduction mode for heavy loading and the switching frequency is fixed at its maximum value. For light loading, the buck converter operates in the discontinuous-conduction mode and its switching frequency is automatically selected among a pre-defined set of frequencies according to the amount of the load current. The load current can be sensed indirectly by monitoring the on-time of power transistor because it is a function of the load current. With the proposed load-adaptive automatic switching frequency selection circuit, the power efficiency of a buck converter implemented in a 0.35-μm 2P4M BCDMOS technology is improved by 24.0-% when the load current load is 10-mA.     

Optimum buck converter with a single switch

A new DC-DC power converter with only one active switch operating at a constant switching frequency and with low-current and voltage stress is proposed. The conduction losses are minimized because of the ability to use a minimum number of elements in the path of direct energy transfer from the input to the load. Furthermore, because only one switch is used, the design of the control circuit is greatly simplified. The new power converter achieves soft switching for the diodes and zero-current switching (ZCS) at turn on for the active switch     

New Architectures for Radio-Frequency DC–DC Power Conversion

This document proposes two new architectures for switched-mode dc–dc power conversion. The proposed architectures enable dramatic increases in switching frequency to be realized while preserving features critical in practice, including regulation of the output across a wide load range and high light-load efficiency. This is achieved in part by how the energy conversion and regulation functions are partitioned. The structure and control approach of the new architectures are described, along with representative implementation methods. The design and experimental evaluation of prototype systems with cells operating at 100MHz are also described. It is anticipated that the proposed approaches and ones like them will allow substantial improvements in the size of switching power converters and, in some cases, will permit their integrated fabrication.     

Frequency-domain characterization of sliding mode control of an inverter used in DSTATCOM application

In this paper, the commonly used switching schemes for sliding mode control of power converters is analyzed and designed in the frequency domain. Particular application of a distribution static compensator (DSTATCOM) in voltage control mode is investigated in a power distribution system. Tsypkin's method and describing function is used to obtain the switching conditions for the two-level and three-level voltage source inverters. Magnitude conditions of carrier signals are developed for robust switching of the inverter under carrier-based modulation scheme of sliding mode control. The existence of border collision bifurcation is identified to avoid the complex switching states of the inverter. The load bus voltage of an unbalanced three-phase nonstiff radial distribution system is controlled using the proposed carrier-based design. The results are validated using PSCAD/EMTDC simulation studies and through a scaled laboratory model of DSTATCOM that is developed for experimental verification.     

多模式开关电源控制芯片的低功耗设计

针对降低多模式开关电源控制芯片在轻载与待机工作模式下功耗,提高其全负载条件下工作效率的需要,提出一种开关电源控制芯片供电系统的设计方案,实现了其在启动、关断、重载、轻载以及待机等各种工作情况下的高效率低功耗工作。该供电系统主要包括欠压锁定电路、数字模块电源单元和两种不同的模拟模块电源单元,以及状态检测模块和模式控制逻辑单元,能够实现电源的上电、掉电控制,同时能够根据电源的负载条件控制各模块的开通关断以实现低功耗工作。该系统已应用于绿色多模式反激式开关控制器的设计中,取得了提高电源效率、降低待机功耗的作用。芯片采用1.5μm BiCMOS工艺设计制成。测试表明,所设计电源的各项指标均已达到设计要求。     

An Accurate, Low-Voltage, CMOS Switching Power Supply With Adaptive On-Time Pulse-Frequency Modulation (PFM) Control

Integrated switching power supplies with multimode control are gaining popularity in state-of-the-art portable applications like cellular phones, personal digital assistants (PDAs), etc., because of their ability to adapt to various loading conditions and therefore achieve high efficiency over a wide load-current range, which is critical for extended battery life. Constant-frequency, pulsewidth modulated (PWM) switching converters, for instance, have poor light-load efficiencies because of higher switching losses while pulse-frequency modulation (PFM) control in discontinuous-conduction mode (DCM) is more efficient at light loads because the switching frequency and associated switching losses are scaled down with load current. This paper presents the design and integrated circuit prototype results of an 83% power efficient 0.5-V 50-mA CMOS PFM buck (step-down) dc-dc converter with a novel adaptive on-time scheme that generates a 27-mV output ripple voltage from a 1.4- to 4.2-V input supply (battery-compatible range). The output ripple voltage variation and steady-state accuracy of the proposed supply was 5 mV (22-27 mV) and 0.6% whereas its constant on-time counterpart was 45 mV (10-55 mV) and 3.6%, respectively. The proposed control scheme provides an accurate power supply while achieving 2%-10% higher power efficiency than conventional fixed on-time schemes with little circuit complexity added, which is critical during light-loading conditions, where quiescent current plays a pivotal role in determining efficiency and battery-life performance     

A Frequency Multiplication Resonant Inverter With Constant Frequency Phase Control

The schematic and analysis of a voltage-fed resonant inverter are presented in this paper. The topology of the inverter allows operation of the resonant tank at higher harmonics and multiples of the switching frequency. The resulting loss in voltage gain is compensated through the use of multiple commutation poles employing low-cost modestly rated MOSFETs. The proposed topology can control power throughput at a fixed frequency through pole phase-shift modulation. Zero voltage switching is maintained down to no load and within the entire input voltage range. Measurements from a multimegahertz 100-W inverter confirm the theoretical predictions, as well as the suggested design and control approach.     

Phase control for resonant DC-DC converter with class-DE inverter and class-E rectifier

In this paper, a phase control scheme for Class-DE-E dc-dc converter is proposed and its performance is clarified. The proposed circuit is composed of phase-controlled Class-DE inverter and Class-E rectifier. The proposed circuit achieves the fixed frequency control without frequency harmonics lower than the switching frequency. Moreover, it is possible to achieve the continuous control in a wide range of the line and load variations. The output voltage decreases in proportion to the increase of the phase shift. The proposed converter keeps the advantages of Class-DE-E dc-dc converter, namely, a high power conversion efficiency under a high-frequency operation and low switch-voltage stress. Especially, high power conversion efficiency can be kept for narrow range control. We present numerical calculations for the design and the numerical analyses to clarify the characteristics of the proposed control. By carrying out circuit experiments, we show a quantitative similarity between the numerical predictions and the experimental results. In our experiments, the measured efficiency is over 84% with 2.5 W output power for 1.0-MHz operating frequency at the nominal operation. Moreover, the output voltage is regulated from 100% to 39%, keeping over 57% power conversion efficiency by using the proposed control scheme.     

A new phase-controlled parallel resonant converter

A phase-controlled resonant converter was obtained by connecting in parallel the AC loads of two identical parallel resonant inverters. A phase shift between the drive signals of the two inverters controls the amplitude of the output voltage of the new inverter. A voltage-driven rectifier is used as an AC load of the inverter, which results in a phase-controlled parallel resonant DC-DC converter. A frequency-domain analysis is performed for the steady-state operation of the inverter, and two types of voltage-driven rectifiers and design equations are derived. The converter can be operated at a constant switching frequency, which reduces EMI problems. It is found that for switching frequencies higher than the resonant frequency by a factor of 1.07, the load of each switching leg is inductive. The converter is capable of regulating the output voltage in the range of load resistance from full-load to no-load. Experimental results are presented for a prototype of the phase-controlled parallel resonant converter with a center-taped rectifier tested at an output power of 50 W and a switching frequency of 116 kHz     

A fully integrated switched-capacitor DC–DC converter with hybrid output regulation

In this paper, we propose a fully integrated switched-capacitor (SC) DC–DC converter with hybrid output regulation that allows a predictable switching noise spectrum. The proposed hybrid output regulation method is based on the digital capacitance modulation for fine regulation and the automatic frequency scaling for coarse regulation. The automatic frequency scaler and on-chip current sensor are implemented to adjust the switching frequency at one of the frequencies generated by a binary frequency divider with change in load current. Thus, the switching noise spectrum of the proposed SC DC–DC converter can be predicted over the entire load range. In addition, the bottom-plate losses due to the parasitic capacitances of the flying capacitors and the gate-drive losses due to the gate capacitances of switches are reduced at light load condition since the switching frequency is automatically adjusted. The proposed SC DC–DC converter was implemented in a 0.13 µm CMOS process with 1.5 V devices, and its measurement results show that the peak efficiency and the efficiency at light load condition are 69.2% and higher than 45%, respectively, while maintaining a predictable switching noise spectrum.     

A New PWM-Controlled Quasi-Resonant Converter for a High Efficiency PDP Sustaining Power Module

A new pulsewidth modulation (PWM)-controlled quasi-resonant converter for a high-efficiency plasma display panel (PDP) sustaining power module is proposed in this paper. The load regulation of the proposed converter can be achieved by controlling the ripple of the resonant voltage across the primary resonant capacitor with a bidirectional auxiliary circuit, while the main switches are operating at a fixed duty ratio and fixed switching frequency. Hence, the waveforms of the currents can be expected to be optimized from the view-point of conduction loss. Furthermore, the proposed converter has good zero-voltage switching (ZVS) capability, simple control circuits, no hign-voltage ringing problem of rectifier diodes, no dc offset of the magnetizing current and low-voltage stresses of power switches. Thus, the proposed converter shows higher efficiency than that of a half-bridge LLC resonant converter under light load condition. Although it shows the lower efficiency at heavy load, because of the increased power loss in auxiliary circuit, it still shows the high efficiency around 94%. In this paper, operational principles, features of the proposed converter, and analysis and design considerations are presented. Experimental results demonstrate that the output voltage can be controlled well by the auxiliary circuit using the PWM method.      

A single-phase active power filter with one-cycle control under unipolar operation

In this paper, analysis and design for a single-phase active power filter (APF) with one-cycle control is presented. The proposed control method eliminates the need of sensing the load current, a nontrivial task of calculating the harmonics and reactive current components, as well as the use of multipliers, as reported by many previously reported approaches. In addition, the switching loss is reduced by employing unipolar operation, where only two out of four switches are operated at switching frequency while the other two are stationary on or off during an entire half-line cycle. The design methodology taking electromagnetic interference filter into account is also discussed in detail. The theoretical analysis is verified by experiments.     

Adaptive duty ratio modulation technique in switching DC–DC converter operating in discontinuous conduction mode

Adaptive duty ratio (ADR) modulation technique in switching DC–DC converter operating in discontinuous conduction mode is proposed in this paper. The proposed ADR modulation technique can regulate the output voltage of the DC–DC converter by generating a series of duty ratios with very simple circuit architecture. The duty ratio is approximately proportional to the square root of the voltage difference between the regulated output voltage and the reference voltage at the beginning of the switching cycle at the light load. As a result, the proposed ADR modulation technique can achieve smaller ripple than the conventional pulse skip modulation over the whole load range. Moreover, the compromise between the light-load ripple and the output power range in the design stage in previous works is solved in the ADR modulation technique. Theoretical analysis, simulation and experimental results are presented to show the operation principle and the advantage of the proposed ADR modulation technique.     

Efficiency improvement in charge pump circuits

Conventional charge pump circuits use a fixed switching frequency that leads to power efficiency degradation for loading less than the rated loading. This paper proposes a level shifter design that also functions as a frequency converter to automatically vary the switching frequency of a dual charge pump circuit according to the loading. The switching frequency is designed to be 25 kHz with 12 mA loading on both inverting and noninverting outputs. The switching frequency is automatically reduced when loading is lighter to improve the power efficiency. The frequency tuning range of this circuit is designed to be from 100 Hz to 25 kHz. A start-up circuit is included to ensure proper pumping action and avoid latch-up during power-up. A slow turn-on, fast turn-off driving scheme is used in the clock buffer to reduce power dissipation. The new dual charge pump circuit was fabricated in a 3-μm p-well double-poly single-metal CMOS technology with breakdown voltage of 18 V, the die size is 4.7×4.5 mm². For comparison, a charge pump circuit with conventional level shifter and clock buffer was also fabricated. The measured results show that the new charge pump has two advantages: (1) the power dissipation of the charge pump is improved by a factor of 32 at no load and by 2% at rated loading of 500 Ω and (2) the breakdown voltage requirement is reduced from 19.2 to 17 V     

DCM,FSM,dead time and width controllers for a high frequency high efficiency buck DC-DC converter over a wide load range

This paper presents a width controller,a dead time controller,a discontinuous current mode(DCM) controller and a frequency skipping modulation(FSM) controller for a high frequency high efficiency buck DC-DC converter. To improve the efficiency over a wide load range,especially at high switching frequency,the dead time controller and width controller are applied to enhance the high load efficiency,while the DCM controller and FSM controller are proposed to increase the light load efficiency.The proposed D...     

RF Class-D Amplification With Bandpass Sigma–Delta Modulator Drive Signals

The power efficiency of a RF Class-D amplifier with a bandpass sigma-delta (SigmaDeltaM) modulator is analyzed for a complementary voltage-switched configuration. The modulator broadens the application of the amplifier to include signals with time varying envelopes such as W-CDMA. The addition of a modulator introduces new design variables which affect amplifier power efficiency including coding efficiency and the average transition frequency of the pulse train. Design equations are derived for the optimum load impedance, output power, conduction losses, capacitive switching losses, and drain efficiency. The general design equations are consistent with both periodic and aperiodic drive signals. Analytic and simulated results are compared for an example design with pseudomorphic high-electron mobility transistor and metal-semiconductor field-effect transistor switches with a fourth-order bandpass SigmaDeltaM. The results show a drain efficiency of 52% with a 10-dB peak-to-average power ratio W-CDMA source signal at a frequency of 500 MHz     

高性能PWM型DC-DC升压变换器研究

设计了一种单片集成PWM型电流模式升压变换器,芯片内部集成了耐压22V的DMOS功率开关管,开关频率为1.6MHz,采用1.5μmBCD工艺实现。芯片具有很宽的输入电压(2.7~14V)、高效率(85%)、低关断电流、快速暂态响应和低功耗等特性,适宜于用作便携式设备的电源管理,也可作为IP核,嵌入同种工艺下的其它芯片。文中除了对芯片设计方法、思路及主要电路模块结构的设计方案进行讨论外,还提出了减小单片集成开关电源噪声的措施。