Output Voltage Range Research Articles

Dynamic Improvement with a Feedforward Control Strategy of Bidirectional DC-DC Converter for Battery Charging and Discharging

With the increasing importance of power accumulator batteries in electric vehicles, the accurate characteristics of power accumulator batteries have an important role. In order to evaluate the power accumulator battery, battery charging and discharging is indispensable. In this article, a H-bridge bidirectional DC-DC converter is presented which can charge and discharge the battery with different voltage levels and one of the merits of this topology is that a wide output voltage range can be easily achieved. In the control part, a proportional-integral (PI) control strategy is adopted to ensure a stable and reliable operation of the converter. Furthermore, compared with the PI control strategy, a duty ratio feedforward control is utilized to obtain the rapid current dynamic response. In this article, firstly, the system configuration for battery charging and discharging is introduced, then the operating principles and mathematical model of the DC-DC converter are analyzed and derived. Secondly, for bidirectional DC-DC converters, the PI control method and duty ratio feedforward control method are put forward and designed. Finally, the simulation model is established based on PSIM software and the experiment platform is also built in lab. The results of the simulation and experiment research show that the H-bridge bidirectional DC-DC converter can operate reliably and stably during the charging, discharging and power flow reverse modes. In addition, the dynamic response of the charging and discharging current can also be further improved by introducing the duty ratio feedforward control method.

High-Performance Megahertz-Frequency Resonant DC–DC Converter for Automotive LED Driver Applications

This paper introduces a megahertz-frequency resonant dc–dc converter that inherently achieves a load-independent output current while maintaining high efficiency across a wide output voltage range. These properties make the proposed converter well-suited for automotive light-emitting diode (LED) driver applications, where a varying number of LEDs need to be driven with a constant current. The proposed converter achieves load-independent output current by utilizing an LCL -T resonant network, and achieves high efficiency using a comprehensive design optimization methodology. This LCL -T resonant converter is also capable of regulating its output current at any desired value by utilizing phase-shift control. The performance of the LCL -T resonant converter is theoretically and experimentally compared with an LC 3 L and an LCLC resonant converter. For the experimental comparison, prototypes LCL -T, LC 3 L , and LCLC resonant converters are designed to operate at 2 MHz and across an output voltage range of 3.3–49.5 V while supplying a constant 0.5 A output current to the LEDs. The LCL -T resonant converter prototype achieves a peak efficiency of 91.1%, which is 0.6% and 1.8% higher than the peak efficiency of the LC 3 L and the LCLC converter prototypes, respectively. Furthermore, the LCL -T converter prototype maintains 0.8% and 1.6% higher average efficiency over its 15:1 output voltage range relative to the LC 3 L and the LCLC converter prototypes, respectively.

A Soft-Charging-Based SC DC–DC Boost Converter With Conversion-Ratio-Insensitive High Efficiency for Energy Harvesting in Miniature Sensor Systems

This paper introduces a fully integrated switched-capacitor (SC) DC-DC boost converter suitable for energy harvesting in miniature sensor systems with varying harvesting source and battery voltages. Unlike the conventional SC DC-DC boost converters, where efficiency is optimized only for a few topology-dependent voltage conversion ratios (VCRs), the proposed soft-charging-based SC converter achieved VCR-insensitive evenly high efficiency for a wide range of input and output voltages. A test chip was fabricated in 180nm process, and the measured peak efficiency and average efficiency are 85.3% and 83.6%, respectively, for 1.8V regulated output voltage and a wide range of input voltages (0.95–1.8 V). Also, a peak efficiency of 88.9% and average efficiency of 87.6% are achieved for a wide range of battery output voltages (3.0–4.2 V) and a 1.2V harvesting source input voltage.

High-Efficiency SiC-Based Isolated Three-Port DC/DC Converters for Hybrid Charging Stations

This article proposes a novel isolated three-port dc/dc converter based on a series resonant converter and a dual active bridge (DAB) converter for electric-vehicle charging stations with fast and slow charging functions. With this three-port structure, the proposed converter has fewer components, which results in lower system cost and volume compared with separate charger systems. A simple control method using phase-shift and frequency modulations was developed to control the output power of the fast and slow charging ports simultaneously. An optimal phase-shift angle was also derived to minimize the transformer current for when only the DAB converter is operated for slow charging. To verify the converter operation, a 5-kW SiC-based prototype with a power density of 2.74 kW/dm3 was built and tested with an input voltage of 600 V. A high-efficiency performance over a wide output voltage range has been achieved, and the peak efficiency is 98.2% at the rated conditions.

A Low-Area and Fully Nonlinear 10-Bit Column Driver With Low-Voltage DAC and Switched-Capacitor Amplifier for Active-Matrix Displays

To reduce the circuit area and support a 10-bit fully nonlinear gamma correction, a new column driver architecture constructed with a 10-bit one-stage low-voltage resistor string digital-to-analog converter (RDAC) (LVDAC) and a switched-capacitor amplifier (SC-AMP) is proposed. Because the LVDAC is implemented with low-voltage (LV) MOSFETs instead of high-voltage (HV) MOSFETs, the circuit area is drastically reduced. In addition, there is no need to use level shifters that must be used in the traditional column driver between the LV logic circuit and the HV DAC, thus further decreasing the circuit area. By utilizing a one-stage DAC architecture, the effective bit resolution of nonlinear gamma correction can be increased compared with previous two-stage DACs, in which the output voltages of the coarse DAC are interpolated. The output voltage of LVDAC is amplified by SC-AMP to reach the requisite HV to drive the display panel. In designing the SC-AMP, the effects of non-idealities, such as random offset voltage, capacitance mismatch, parasitic capacitance, and switching error are quantitatively analyzed, and circuit techniques to suppress the effects are presented. The proposed column driver was fabricated using a 90-nm CMOS process. The circuit area of the proposed 10-bit column driver is only 69.0% of that of the conventional 8-bit column driver because the conventional 8-bit HV RDAC (HVDAC) using 5-V MOSFETs is replaced by the proposed 10-bit LVDAC using 1.2-V MOSFETs, along with the SC-AMP with a gain of four to support the 5-V output voltage range. The measurement results show that the differential nonlinearity (DNL) and integral nonlinearity (INL) are +0.2/-0.18 and +0.42/-0.06 LSB, respectively, with an LSB voltage of 4.5 mV. The measured maximum deviation of voltage outputs (DVOs) between 50 channels is 7.9 mV.

High-Frequency Wide-Range Resonant Converter Operating as an Automotive LED Driver

This article introduces an immittance network-based wide-range LCL-T resonant dc–dc converter, where two control variables, a phase shift between two inverter half-bridges, and a phase shift between inverter and rectifier half-bridges, are utilized to achieve output current regulation while minimizing losses over wide ranges of input and output voltages. A practical control strategy is developed to adjust the phase shifts so that zero voltage switching of all devices is achieved while minimizing conduction losses. Efficiency improvements over a standard LCL-T converter are demonstrated by loss modeling and by experiments. The features of the proposed WR-LCL-T converter are well suited for automotive LED drivers. Experimental results demonstrating operation with the loss minimizing control strategy are shown for a 2-MHz converter prototype operating from an input voltage ranging from 8 to 18 V, and delivering 0.5-A output current to a string of 1–14 LEDs, which corresponds to an output voltage range of 3–45 V. Using silicon MOSFETs, the prototype achieves a peak power stage efficiency of 92.4% and maintains greater than 86% power stage efficiency across the wide input and output voltage ranges.

Analysis and design of inductive wireless power transfer link for feedback-less power delivery to enclosed compartment

The paper presents analytical investigation and hands-on design of inductive wireless power transfer link for a through-glass AC power delivery system into enclosed compartment such as industrial glove box or vehicle cabin. The system is fed from AC grid and creates a standard AC outlet within the enclosed compartment, capable of supplying loads of up to 1 kW. The system consists of three (namely, AC/DC, DC/DC and DC/AC) conversion stages, with the former and the latter realized by standard off-the-shelf units. The intermediate DC-DC power conversion stage, which is the paper focus, is realized by a from-scratch-built inductive wireless power transfer link, operating in load-independent voltage output regime without any feedback. It was recently shown that the output voltage of such a system, even when operating at load-independent frequency, remains influenced by the load due to practical issues. As a result, the output voltage resides within a certain range rather than remains constant, obtaining minimum/maximum values under rated load/no-load conditions, respectively. Since coils separating glass width typically possesses some finite uncertainty, values of both coupling coefficient and coils self-inductances may be different than nominal (design) ones and hence the output voltage would drift from its nominal range. Hence, due to the fact that upper and lower bounds of an inductive wireless power transfer link output voltage range are limited by DC link capacitor and DC/AC power stage constraints, tolerated glass width uncertainty is obtained in the paper. Moreover, compensating capacitors pair symmetrizing uncertainty tolerance of the inductive wireless power transfer link is also revealed. Simulations and experiments based on 400 V, 1 kW-rated inductive wireless power transfer link are presented to validate the analysis.

A 22.5–31.2-GHz Continuously Tuning Frequency Synthesizer With 8.7-GHz Chirp for FMCW Applications

This letter presents a fractional-N frequency synthesizer with an ultrawideband continuously tuning range of 32.4% centered at 26.85- and 8.7-GHz chirp for frequency-modulated continuous-wave (FMCW) radars. The synthesizer uses a fractional-N 9-GHz charge-pump phase-locked loop (CPPLL) cascaded by an injection-locked frequency tripler (ILFT). A voltage-controlled oscillator (VCO) with transformer (TFM) coupling for an enhanced linear control voltage range, a better quality factor and good isolation from the load seen by the resonator, and a wide output voltage range charge-pump (CP) are used to achieve the ultrawideband CPPLL. The ILFT is implemented using a weakly coupled TFM for broadband locking range and 3-dB output power. The synthesizer is fabricated in the 40-nm CMOS technology and consumes 28.5 mW. The phase noise (PN) of the synthesizer at 27 GHz is -97.87 dBc/Hz at 1 MHz and the prototype is capable of generating a triangle or sawtooth chirp of 8.7-GHz modulation bandwidth with an rms FM error of 0.04% of BWchirp.

Investigation on Performance of Cu/Ni Film as Low Temperature Sensor

This research has investigated the effect of deposition time on the performance of Cu/Ni thin film as low temperature sensor. The sample was carried out by using electroplating technique on various deposition times from 1-5 minute. The liquid nitrogen was used as low temperature medium which the temperature was regulated from 0°C down to -200°C and vice versa. All Cu/Ni sensors perform a good response on the temperature change with variation of the output voltage range, time constants, sensitivity, and hysteresis losses. The Cu/Ni film produced during 1 minute deposition is the most sensitive sensor with sensitivity of (1.25 + 0.01) mV/°C, but rather slow in responding temperature change and rather less stable voltage compared with the Cu/Ni film produced in 4 minute deposition. Unfortunately, the 4 minute sample is less sensitive in responding temperature change, that is (1.00 + 0.01) mV/°C. We also found that all sensors have various hysteresis losses. The Cu/Ni film produced in 3 minute deposition has the minimum hysteresis area that is (6.640 ± 0.005)V°C.

A Current-Mode-Hysteretic Buck Converter With Constant-Frequency-Controlled and New Active-Current-Sensing Techniques

This article presents a hysteretic-current-controlled buck converter with constant-frequency-controlled and active-current-sensing (ACS) techniques. This converter used phase-frequency-locked techniques to achieve constant switching frequency. Even if the input voltage or output load current changes, the switching frequency will be as stable as possible at 1 MHz. The proposed ACS circuit will not generate sparks, so the current feedback loop does not need a sample-and-hold circuit, and that will reduce the transient response time. The proposed buck converter has been fabricated with TSMC 0.35 μm CMOS 2P4M technology; the total area of the chip is 1.5 mm × 1.5 mm. The measurement results of this buck converter show that the maximum power efficiency is 90% when the output voltage is 2.5 V and the load current is 300 mA. The output voltage range is 2.5-1 V, and the maximum load current is 600 mA. When the load current varies between 100 and 500 mA, the load transient response is 2.6 μs/2.2 μs and undershoot/overshoot is 20 mV/30 mV. The switching frequency of this buck converter is locked at 1 MHz and the voltage error is within 1%.

A 4-MHz Digitally Controlled Voltage-Mode Buck Converter With Embedded Transient Improvement Using Delay Line Control Techniques

In this article, a digitally controlled voltage-mode buck converter with embedded transient improvement using delay line-based control techniques is presented. Two voltage-controlled delay lines (VCDL's) are used to convert the difference between the feedback and reference voltages to a delay time difference. The delay difference is then fed to the multiple-outputs bang-bang phase detector (MOBBPD), which converts the input delay difference to multiple-bits digital codes in a simple nonlinear way. The MOBBPD scheme leads to high resolution for small output ripple and improved response when large load transient happens in a low-cost way. A digital loop filter (DLF) accumulates the MOBBPD output codes to control the duty cycle through a novel digital pulse width modulator (DPWM) to regulate the output voltage. By designing the coefficients of the DLF, a type-II compensator can be achieved through the integral and proportional paths to make the loop stable. The proposed DPWM, which consists of a divide-by-8 frequency divider, two delay lines and a few simple digital logics, achieves a wide tunable range of duty cycle under various process corners and supply voltages. A proof-of-concept design of the proposed buck converter was fabricated in a standard 0.18μm CMOS technology. The measured results show that it achieves a very wide output voltage range from 0.1 V to 3.5 V for a input supply range from 2.4 V to 3.6 V. With a 400 mA step in the load current, the overshoot/undershoot is less than 87 mV and the 1% settling time is less than 16μs. The peak efficiency is 95.2% with 250 mA load current at 2.4 V output voltage with 3.3 V input voltage.

A Hybrid Control Strategy of LCC-S Compensated WPT System for Wide Output Voltage and ZVS Range With Minimized Reactive Current

To regulate the output voltage of inductor–capacitor–capacitor-series ( <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LCC</i> -S) compensated wireless power transfer (WPT) system, a hybrid control strategy of phase shift modulation (PSM) and a switch-controlled capacitor is presented in this article. In the proposed hybrid control strategy, <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LCC</i> -S compensated WPT system can realize wide output voltage regulation with zero voltage switching (ZVS), and the reactive current in a resonant tank can be minimized in the whole voltage range. Besides, the current in the primary coil of <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LCC</i> -S compensated WPT system can be regulated with PSM, which helps to reduce the power loss of the primary coil at light load. Compared with conventional dual-loop hybrid control, the proposed hybrid control can regulate two control variables with one feedback loop simultaneously. To verify the theoretical analysis, a 500-W prototype with 400-V input voltage, 100−250-V output voltage is built. The experimental results show that the inverter can realize ZVS within the whole voltage range and a peak efficiency of 94.7% can be obtained.

A Three-Phase Asymmetrical Dual-Active-Bridge Converter With Series/Parallel-Reconfigurable Output for Wide Voltage Range Applications

A three-phase asymmetrical dual active bridge (TP-ADAB) dc-dc converter with series/parallel-reconfigurable output (SPRO) is proposed for wide output range and constant peak power applications. The three outputs of the TP-ADAB converter are able to be connected in series or parallel to achieve wide output voltage range. The output voltage range, maximum output voltage/current of each power module, as well as the power rating of devices, are reduced significantly. Moreover, automatic voltage sharing in output series mode and current sharing in output parallel mode is achieved by adopting the three-phase structure. Furthermore, soft-switching of all power switches is achieved in a wide operation range. Operation principles, output characteristics, soft-switching performances, and control strategy of the proposed TP-ADAB converter are analyzed in detail. Experimental results of a 3 kW prototype are provided to verify the effectiveness and feasibility of the proposed converter.

A voltage-adjustable output-capacitorless LDO regulator with split-length current mirror compensation and overshoot/undershoot reduction

An output-capacitorless low-dropout regulator (OCL-LDO) using split-length current mirror compensation and overshoot/undershoot reduction circuit are presented in this paper. At a supply of 1.5 V and a quiescent current of 8.2 µA, the proposed scheme can support a maximum load current of 50 mA. The proposed OCL-LDO has a range of output voltage from 0.8 to 1.25 V with 1.5 V supply. The proposed regulator is designed and post-simulated by UMC 55-nm standard CMOS process. The simulation results show that the proposed scheme is stable in different temperatures and process corners with 10 pF output capacitor. The maximum value of overshoot and undershoot is 69.0 mV and 91.5 mV, respectively.

An Ultrawide Output Range ${LLC}$ Resonant Converter Based on Adjustable Turns Ratio Transformer and Reconfigurable Bridge

This article proposes an ultrawide output range LLC resonant converter based on adjustable turns ratio transformer and reconfigurable bridge. Due to the reconfiguration of the transformer by two four-quadrant switches, the transformer exhibits three different effective turns ratios, which correspond to three output ranges. Moreover, in case of lower output voltage, the primary side is reconfigured as a half-bridge to further extend the output voltage range. The design of resonant tank parameters is less constrained by the voltage gain requirement. The switching frequency range in each mode can be squeezed close to the resonant frequency, which contributes to an improved soft switch performance. The operational principles, design considerations, and mode transition are analyzed. A 4 A rated prototype that converts 390 V input to a 60-450 V output is designed and tested to validate the concept. A smooth mode transition is achieved without transient issues. The design prototype demonstrates 97.50$\%$ peak efficiency and good overall efficiency performance over this ultrawide output range.

Hybrid Dickson Switched-Capacitor Converter With Wide Conversion Ratio in 65-nm CMOS

Hybrid switched-capacitor (SC) converters have shown great promise in achieving high efficiency and power density for dc–dc conversion. By combining an SC stage with an inductor filter stage, benefits from both approaches can be realized. In this work, a hybrid Dickson SC converter with a 4:1 native conversion ratio and regulated output voltage range of 0.3–0.9 V from a 3.4 to 4.2-V lithium-ion battery and the effective switching frequency of 1 MHz was implemented in 65-nm bulk CMOS process. The converter achieves maximum output current of 1.5 A, the power density of 330 mW/mm2, and a peak efficiency of 92.6%. The converter is packaged using flip-chip technology with passive devices co-packaged through a high-density interposer to minimize the packaging parasitics and volume. A segmented gate driver is used to enhance the converter efficiency and reliability by maintaining low-voltage ringing across the power switches. The converter is integrated with closed-loop output voltage regulation, dead-time control, and active capacitor–voltage balancing to maximize the active and passive device utilizations.

Implementation of Phase Shifted Carrier Modulation Technique for Cascaded Five-Level Inverter Using FPGA

This paper presents the development of Xilinx Field Programmable Gate Array (FPGA) to control single phase Cascaded Multilevel Inverter (MLI). FPGA realizes high speed switching and attains a high over sampling rate. The FPGA provide eight control signals for five level output voltage using Phase Shifted Carrier (PSC) modulation technique. All the function modules of the designed program was implemented using Very High Speed Integrated Circuit Hardware Description Language (VHDL) and Xilinx ISE 9.2i software was employed as a simulation and compiler tool. The proposed strategy can provide a wide range of rms output voltage by varying the modulation index. The simulation of the system was carried out by Matlab/Simulink. Simulation and experimental results are provided.

Performance evaluation of constant current and constant voltage charge control modes of an inductive power transfer circuit with double-sided inductor-capacitor-capacitor and inductor-capacitor/series compensations for electrical vehicle battery charge applications

For electric vehicle (EV) battery chargers, inductive power transfer (IPT) has become popular day by day due to its features such as being safe, comfortable and weather proof. The constant current (CC) and the constant voltage (CV) charge control modes are important for high-efficiency charging and long-life use of Lithium-ion (Li-ion) batteries commonly used in EVs. However, IPT method requires a wide range of operating frequency in order to provide CC/CV charge control modes. In IPT applications, CC and CV charge control modes are mainly achieved with dc-dc circuits using compensation networks at the transmitter and receiver sides. In this study, performances of inductor-capacitor/series compensation and double-sided inductor-capacitor-capacitor compensation topologies are evaluated based on CC/CV charge control modes. The analytical evaluation is presented in terms of voltage and current regulations during the entire charge control period. Finally, presented analytical evaluation is confirmed with ANSYS software providing field-electric common simulation to predict real response of compensation topologies. In the simulation work, both compensation topologies are operated for the maximum 2.5 kW output power and at the 250 V-450 V output voltage range.

Isolated LLC converter for PEV charging for wide‐range voltage gain using six‐switch bridge

AbstractThis paper proposes a dual LLC converter based on a six‐switch bridge to charge deeply depleted plug‐in electric vehicle onboard battery packs. The primary‐side switch network comprises an input series or parallel, and two types of transformer‐independent modes. Thus, there are four operation modes. In the input series mode, normalized voltage gains are scaled to 0.5; therefore, a low output voltage can be obtained. In addition, in the input parallel mode, the normalized voltage gains are scaled to 2.0. These four modes operate at the resonant frequency at the switching frequency. Therefore, the efficiency performance can be optimized over a wide output voltage range. The validity of the proposed system is confirmed with a 1‐kW prototype.

Extend output voltage range of AC/AC converters using a reversible indirect matrix converter

AbstractThis paper proposes a reversible indirect matrix converter that expands the output voltage range. The proposed circuit has two operation modes. A buck mode that supplies an output voltage lower than the input voltage, and a boost mode that supplies an output voltage higher than the input voltage. In the boost mode, the proposed circuit has the characteristics of the current type inverter therefore, it is possible to obtain an output voltage with less harmonics. The proposed system is validated with a 2 kW prototype. The proposed circuit shows that the input/output voltage ratio of AC/AC direct conversion obtained is 0 to 1.2 or more. Moreover, the conversion efficiency of the proposed circuit is 92.8%.