Alternating Current–Direct Current(AC–DC)converters require a high value bulk capacitor or afilter capacitor between the DC–DC conversion stages,which in turn causes many problems in the design of a AC–DC converter...Alternating Current–Direct Current(AC–DC)converters require a high value bulk capacitor or afilter capacitor between the DC–DC conversion stages,which in turn causes many problems in the design of a AC–DC converter.The component package size for this capacitor is large due to its high voltage rating and capacitance value.In addition,the high charging current creates more pro-blems during the product compliance testing phase.The shelf life of these specific high value capacitors is less than that of Multilayer Ceramic Capacitors(MLCC),which limits its use for the highly reliable applications.This paper presents a fea-sibility study to overcome these two problems by adding a few sensing mechan-isms to the typical AC–DC converter topology.In majority of the AC–DC converter,Al-Elko capacitor takes approximately 3%to 5%of the converter size.The proposed method reduces this to approximately 50%size and so it effectively approximates 2%to 3%size reduction in converter size.The proposed method basically works based on the load current prediction method and hence it is highly suitable for the constant load application.Moreover,the converter response time increases in this method,which limit its application in high-speed systems.The high temperature application of Al-Elko capacitor is limited because of its poor performance,which is significantly rectified by replacing the Al-Elko with MLCC as it delivers good performance in high temperature.展开更多
针对电动汽车充电电源额外热量产生影响电池使用寿命的问题,提出一种无电解电容隔离式单级双向AC/DC变换器。该变换器能有效阻止低频功率纹波注入电池单元,减少了额外热量的产生;同时电解电容的消除也大大提高了系统的可靠性。控制策略...针对电动汽车充电电源额外热量产生影响电池使用寿命的问题,提出一种无电解电容隔离式单级双向AC/DC变换器。该变换器能有效阻止低频功率纹波注入电池单元,减少了额外热量的产生;同时电解电容的消除也大大提高了系统的可靠性。控制策略方面,提出的一种四相控制器,不仅能使所有开关管实现零电压开关(Zero Voltage Switch,ZVS),并在导通损耗进行了性能优化。最后,通过PSIM仿真软件和实验样机,验证了理论分析的正确性和可行性。展开更多
The electrolytic-capacitor-less(EL-cap-less)technique has been attracting more and more interests in these years.The EL-cap-less single-phase to three-phase inverter(STI)with front-end diode rectifier is applied to ho...The electrolytic-capacitor-less(EL-cap-less)technique has been attracting more and more interests in these years.The EL-cap-less single-phase to three-phase inverter(STI)with front-end diode rectifier is applied to home electrical appliances.In EL-cap-less systems,film-type capacitor is used to suppress the high-frequency ripple components instead of smoothing the DC-link voltage.By using the EL-cap-less solution,reliability can be improved,lifetime can be increased and high power factor(PF)also can be realized.The EL-cap-less STI brings the opportunity to simplify system structure and lower cost.Because a certain DC-link capacitance is still required,the real PF is limited.To further improve the PF,the ripple components of current references are made in synchronous with the DClink voltage.And the capacitance chosen guideline of the film-type capacitor also be presented.A prototype is built to verify its real performance.展开更多
To miniaturize a very low level dc current amplifier and to improve its output response speed, the switched capacitor negative feedback circuit (SCNF), instead of the conventionally used high-ohmage resistor, is prese...To miniaturize a very low level dc current amplifier and to improve its output response speed, the switched capacitor negative feedback circuit (SCNF), instead of the conventionally used high-ohmage resistor, is presented in this paper. In our system, a switched capacitor filter (SCF) and an offset controller are also used to decrease vibrations and offset voltage at the output of the amplifier using SCNF. The theoretical output voltage of the very low level dc current amplifier using SCNF is obtained. The experimental results show that the unnecessary components of the amplifier’s output are much decreased, and that the response speed of the amplifier with both the SCNF and SCF is faster than that using high-ohmage resistor.展开更多
文摘Alternating Current–Direct Current(AC–DC)converters require a high value bulk capacitor or afilter capacitor between the DC–DC conversion stages,which in turn causes many problems in the design of a AC–DC converter.The component package size for this capacitor is large due to its high voltage rating and capacitance value.In addition,the high charging current creates more pro-blems during the product compliance testing phase.The shelf life of these specific high value capacitors is less than that of Multilayer Ceramic Capacitors(MLCC),which limits its use for the highly reliable applications.This paper presents a fea-sibility study to overcome these two problems by adding a few sensing mechan-isms to the typical AC–DC converter topology.In majority of the AC–DC converter,Al-Elko capacitor takes approximately 3%to 5%of the converter size.The proposed method reduces this to approximately 50%size and so it effectively approximates 2%to 3%size reduction in converter size.The proposed method basically works based on the load current prediction method and hence it is highly suitable for the constant load application.Moreover,the converter response time increases in this method,which limit its application in high-speed systems.The high temperature application of Al-Elko capacitor is limited because of its poor performance,which is significantly rectified by replacing the Al-Elko with MLCC as it delivers good performance in high temperature.
文摘针对电动汽车充电电源额外热量产生影响电池使用寿命的问题,提出一种无电解电容隔离式单级双向AC/DC变换器。该变换器能有效阻止低频功率纹波注入电池单元,减少了额外热量的产生;同时电解电容的消除也大大提高了系统的可靠性。控制策略方面,提出的一种四相控制器,不仅能使所有开关管实现零电压开关(Zero Voltage Switch,ZVS),并在导通损耗进行了性能优化。最后,通过PSIM仿真软件和实验样机,验证了理论分析的正确性和可行性。
基金supported by the Fundamental Research Funds for the Central Universities (No.NT2018011)the China Postdoctoral Science Foundation (No.2015M580424)
文摘The electrolytic-capacitor-less(EL-cap-less)technique has been attracting more and more interests in these years.The EL-cap-less single-phase to three-phase inverter(STI)with front-end diode rectifier is applied to home electrical appliances.In EL-cap-less systems,film-type capacitor is used to suppress the high-frequency ripple components instead of smoothing the DC-link voltage.By using the EL-cap-less solution,reliability can be improved,lifetime can be increased and high power factor(PF)also can be realized.The EL-cap-less STI brings the opportunity to simplify system structure and lower cost.Because a certain DC-link capacitance is still required,the real PF is limited.To further improve the PF,the ripple components of current references are made in synchronous with the DClink voltage.And the capacitance chosen guideline of the film-type capacitor also be presented.A prototype is built to verify its real performance.
文摘To miniaturize a very low level dc current amplifier and to improve its output response speed, the switched capacitor negative feedback circuit (SCNF), instead of the conventionally used high-ohmage resistor, is presented in this paper. In our system, a switched capacitor filter (SCF) and an offset controller are also used to decrease vibrations and offset voltage at the output of the amplifier using SCNF. The theoretical output voltage of the very low level dc current amplifier using SCNF is obtained. The experimental results show that the unnecessary components of the amplifier’s output are much decreased, and that the response speed of the amplifier with both the SCNF and SCF is faster than that using high-ohmage resistor.
