CN117997128A - 开关电源电路 - Google Patents

开关电源电路 Download PDF

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CN117997128A
CN117997128A CN202311448280.8A CN202311448280A CN117997128A CN 117997128 A CN117997128 A CN 117997128A CN 202311448280 A CN202311448280 A CN 202311448280A CN 117997128 A CN117997128 A CN 117997128A
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capacitor
voltage
switch
rectifier
active clamp
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相马将太郎
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Aiba Shotaro
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Aiba Shotaro
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    • HELECTRICITY
    • H02GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02MAPPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M1/00Details of apparatus for conversion
    • H02M1/32Means for protecting converters other than automatic disconnection
    • H02M1/34Snubber circuits
    • H02M1/342Active non-dissipative snubbers
    • HELECTRICITY
    • H02GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02MAPPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M3/00Conversion of dc power input into dc power output
    • H02M3/22Conversion of dc power input into dc power output with intermediate conversion into ac
    • H02M3/24Conversion of dc power input into dc power output with intermediate conversion into ac by static converters
    • H02M3/28Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac
    • H02M3/325Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal
    • H02M3/335Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only
    • H02M3/33569Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only having several active switching elements
    • H02M3/33576Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only having several active switching elements having at least one active switching element at the secondary side of an isolation transformer
    • H02M3/33592Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only having several active switching elements having at least one active switching element at the secondary side of an isolation transformer having a synchronous rectifier circuit or a synchronous freewheeling circuit at the secondary side of an isolation transformer
    • HELECTRICITY
    • H02GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02MAPPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M1/00Details of apparatus for conversion
    • H02M1/0048Circuits or arrangements for reducing losses
    • H02M1/0054Transistor switching losses
    • H02M1/0058Transistor switching losses by employing soft switching techniques, i.e. commutation of transistors when applied voltage is zero or when current flow is zero
    • HELECTRICITY
    • H02GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02MAPPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M1/00Details of apparatus for conversion
    • H02M1/0064Magnetic structures combining different functions, e.g. storage, filtering or transformation
    • HELECTRICITY
    • H02GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02MAPPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M1/00Details of apparatus for conversion
    • H02M1/42Circuits or arrangements for compensating for or adjusting power factor in converters or inverters
    • H02M1/4208Arrangements for improving power factor of AC input
    • H02M1/4241Arrangements for improving power factor of AC input using a resonant converter
    • HELECTRICITY
    • H02GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02MAPPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M1/00Details of apparatus for conversion
    • H02M1/42Circuits or arrangements for compensating for or adjusting power factor in converters or inverters
    • H02M1/4208Arrangements for improving power factor of AC input
    • H02M1/4258Arrangements for improving power factor of AC input using a single converter stage both for correction of AC input power factor and generation of a regulated and galvanically isolated DC output voltage
    • HELECTRICITY
    • H02GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02MAPPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M3/00Conversion of dc power input into dc power output
    • H02M3/22Conversion of dc power input into dc power output with intermediate conversion into ac
    • H02M3/24Conversion of dc power input into dc power output with intermediate conversion into ac by static converters
    • H02M3/28Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac
    • H02M3/325Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal
    • H02M3/335Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only
    • H02M3/33507Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only with automatic control of the output voltage or current, e.g. flyback converters
    • HELECTRICITY
    • H02GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02MAPPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M3/00Conversion of dc power input into dc power output
    • H02M3/01Resonant DC/DC converters
    • HELECTRICITY
    • H02GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02MAPPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M3/00Conversion of dc power input into dc power output
    • H02M3/22Conversion of dc power input into dc power output with intermediate conversion into ac
    • H02M3/24Conversion of dc power input into dc power output with intermediate conversion into ac by static converters
    • H02M3/28Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac
    • H02M3/325Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal
    • H02M3/335Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only
    • H02M3/33569Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only having several active switching elements
    • H02M3/33571Half-bridge at primary side of an isolation transformer
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02BCLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
    • Y02B70/00Technologies for an efficient end-user side electric power management and consumption
    • Y02B70/10Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Dc-Dc Converters (AREA)

Abstract

本发明提供一种小型、高效率且低噪声的绝缘型开关电源电路。开关电源电路(S10)包括:具有NP匝的一次绕组和NS匝的二次绕组的变压器(T1),和构成一次侧半桥的驱动器开关(Q1),和有源钳位开关(Q2),和对变压器的放电能量进行充电的升压电容器(CBULK1),和串联连接的整流二极管(D1),和整流二极管(D2),和槽路电容器(CT1)以及输出电容器(COUT1)。当驱动开关(Q1)或有源钳位开关(Q2)导通时,使二次侧绕组电压保持在槽路电容器(CT1)中,并且通过将驱动开关(Q1)或有源钳位开关(Q2)断开时的二次绕组电压叠加在保持在槽路电容器(CT1)中的电压上,得到输出电压(VOUT)=升压电压(VBULK)×NS/NP。

Description

开关电源电路
技术领域
本发明涉及一种有源钳位型开关电源电路。
背景技术
典型的反激式转换器设计为通过RCD缓冲器耗散存储在漏电感中的能量,并且这种损耗与开关频率成比例地增加,从而阻碍了器件在较高频率下的小型化。此外,由于漏电感而导致的高频开关节点的振铃引起噪声并阻碍输入滤波器的小型化。
为了解决这些问题,已经提出了具有有源钳位反激式的开关电源电路(例如,专利文献1或非专利文献1)。
有源钳位反激式的一个特点是,有源钳位开关将存储在漏电感中的能量充电到钳位电容中,并在向二次侧传输功率时将其释放,从而不会使存储在漏电感中的能量耗散。由此,能够减少与漏电感的开关频率成比例的损耗并提高频率。
此外,开关节点被钳位到钳位电容,这样在没有振铃的情况下有效地降低了噪声。
此外,通过开发控制IC来优化有源钳位开关的控制,已经可以使用磁化电感的逆向电流来实现ZVS(零电压开关),从而显著降低与开关相关的损耗和噪声。
这些效应使得通过减小变压器和滤波器的尺寸来配置小型、高效且低噪声的开关电源成为可能。
发明内容
发明所要解决的技术问题
然而,即使在有源钳位反激式中,二次侧开关节点也具有与典型反激式转换器相同的配置,因此开关节点产生振铃。
图1显示了典型有源钳位反激式的电路图示例。
输入电压VINACF是使用桥式二极管BDACF将从交流电源VACACF输入的交流电压转换而成的直流电压,从输入电压VINACF经由变压器向绝缘的二次侧输出输出电压VOUTACF。控制电路U2ACF向控制电路U1ACF输出绝缘的反馈信号,控制电路U1ACF基于该反馈信号,以互补的方式操作驱动开关Q1ACF和有源钳位开关Q2ACF,以将输出电压VOUTACF控制在期望值。输入电容器CINACF用于保持输入电压。为了方便后述说明,变压器T1ACF使用由理想变压器TrACF、磁化电感LmACF和漏电感LrACF组成的模型。另外,一次绕组:二次绕组的比设为NP:NS。
图2显示的是当图1中的NP:NS=5:1时的各电压和电流波形。从图2可以看出,当二次侧开关节点电压LX2ACF增加时,振铃的幅度变大。例如,对于20V输出的转换器,整流二极管DACF需要100V~150V的耐受电压。另外,由幅度的大小和振铃引起的噪声也是一个问题,因此需要噪声对策部件。
为了解决上述课题,本发明包括以下配置。
本发明的开关电源电路,其特征在于,包括:
变压器,其具有一次绕组和二次绕组;
驱动器开关,其驱动所述变压器;
有源钳位开关,当所述驱动器开关断开时钳位一次侧开关节点;
大容量电容器,其用于释放钳位能量;
第一整流器、第二整流器;
槽路电容器、输出电容器;
反馈电路,其根据输出电压输出反馈信号;以及
控制电路,其根据所述反馈信号控制所述驱动器开关和所述有源钳位开关;
其中,一次侧开关节点通过所述驱动器开关或所述有源钳位开关钳位在所述大容量电容器的正极或负极,
二次侧开关节点通过所述第一整流器或所述第二整流器钳位在所述输出电容器的正极或负极,
输出电压为与所述大容量电容器电压的所述一次绕组的匝数与所述二次绕组的匝数之比对应的电压。
发明效果
根据本发明,能够提供一种小型、高效率、低噪声且能够在宽输入电压范围内动作的绝缘型开关电源。
以下参照附图对本发明的实施例进行详细描述。
附图说明
【图1】示出了典型的有源钳位反激式的电路图。
【图2】示出了图1中所示的有源钳位反激式的工作波形图。
【图3】示出了关于实施例1的电路图。
【图4】示出了图3中的实施例1的工作波形图。
【图5】示出了关于实施例2的电路图。
【图6】示出了图5中的实施例2的工作波形图。
【图7】示出了实施例2进行功率因数校正时的工作波形图。
【图8】示出了图7的放大视图。
具体实施方式
接下来,使用实施例说明用于实施本发明的实施方式。
【实施例1】
首先,使用图3来说明本发明的实施例。开关电源电路S100经由变压器将来自输入电压VIN的输出电压VOUT输出到绝缘的二次侧,该输入电压VIN是使用桥式二极管BD1对从交流电源VAC1输入的交流电压进行转换而得到的直流电压。反馈电路U2向控制电路U1输出绝缘的反馈信号,控制电路U1基于该反馈信号互补的操作驱动开关Q1、有源钳位开关Q2,从而将输出电压VOUT控制为期望的电压。输入电容器CIN1用于暂时保持输入电压。旁路二极管DIN1用于在输入电压VIN高于升压电压VBULK的情况下对CBULK进行充电,使得升压电压VBULK成为输入电压VIN。如本节稍后所述,将变压器T1表示为由一个包括理想变压器Tr、磁化电感Lm和漏电感Lr构成的模型。另外,一次绕组与二次绕组的比设为NP:NS。
接着,使用图4所示的工作波形进一步详细描述本示例的工作。
关于时段T1:时段T1开始于当一次侧开关节点电压LX1为低时驱动开关Q1导通。因此,由于驱动开关Q1的Vds是零电压,所以驱动开关Q1成为零电压开关(ZVS)。由于驱动开关Q1导通,能量累积在变压器T1中,磁化电流ILm增加。由于输入电压VIN被施加到一次绕组,因此理想变压器Tr在二次绕组中产生等于输入电压VIN×NS/NP的电压。由于二次侧开关节点电压LX2被整流二极管D2钳位到二次侧基准电压SGND,因此槽路电容器CT1被充电等于输入电压VIN×NS/NP的电压。另外,槽路电容器CT1通过二次侧整流电流ISec充电。为了保持输出电压VOUT,输出电容器COUT1向负载RLOAD1放电输出电容电流ICOUT1。然后,驱动开关Q1断开,由此,通过磁化电流ILm,一次侧开关节点电压LX1向高转变,一次侧开关节点电压LX1经由有源钳位开关Q2的体二极管被钳位到升压电压VBULK。
关于时段T2:时段T2开始于当一次侧开关节点电压LX1为高时有源钳位开关Q2导通。因此,由于有源钳位开关Q2的Vds是零电压,所以有源钳位开关Q2成为零电压开关(ZVS)。由于有源钳位开关Q2导通,所以谐振电流ILr流向升压电容器CBULK1,升压电容器对其进行充电和放电。这里重要的是,如果有源钳位开关Q2不是有源钳位而是二极管,则不能放电,即负电流无法流过。如果不能放电,则升压电压VBULK别无选择,只能继续上升,最终达到每个元件的击穿电压。然而,由于有源钳位开关Q2是有源钳位,所以可以释放漏电感Lr的能量,并且可以有效地将该能量传递到二次侧。
由于一次绕组上被施加了(升压电压VBULK–输入电压VIN)的电压,因此二次侧绕组通过理想变压器Tr会产生(升压电压VBULK–输入电压VIN)×NS/NP的电压。二次侧开关节点电压LX2由整流二极管D1钳位到输出电压VOUT。由于槽路电容器CT1由变压器T1处的输入电压VIN×NS/NP的电压充电,因此输出电压VOUT被充电的是将理想变压器Tr的二次绕组电压(升压电压VBULK–输入电压(VIN)×NS/NP叠加在槽路电容器CT1的电压而获得的电压。换言之,输出电压VOUT=输入电压VIN×NS/NP+(升压电压VBULK–输入电压VIN)×NS/NP=升压电压VBULK×NS/NP,在输出电压VOUT中产生具有升压电压VBULK的绕组比的电压。
此外,输出电容器COUT1由二次侧整流电流ISec充电。输出电容电流ICOUT1流向输出电容器COUT1,该输出电容电流ICOUT1是向负载RLOAD1的放电电流与由于二次侧整流电流ISec而产生的充电电流之间的差。
然后,当磁化电流ILm变为负电流时,有源钳位开关Q2断开,并且一次侧开关节点电压LX1通过磁化电流ILm而向低转变,并且经由驱动开关Q1的体二极管钳位到GND。
另外,由于磁化电流ILm不输出到变压器外部,因此无法直接监测。对于该课题,可以使用搭载了TI公司的UCC28780或ONSEMI公司的NCP1568中使用的自适应型的控制IC(参照非专利文献4的第7.4.1节)作为控制电路U1,能够调整有源钳位开关Q2的导通时间,并将磁化电流ILm的负电流控制为驱动开关Q1作为ZVS操作的最佳值。
另外,关于本实施例的本质课题,在于当升压电压VBULK低于输入电压VIN时,通过旁路二极管DIN1或有源钳位开关Q2的体二极管将升压电压VBULK提高到输入电压VIN,因此升压电压VBULK需要设定得比输入电压VIN高。
例如,如果本实施例中交流电源电压在AC100V~AC240V的范围内,则输入电压VIN最大为240V×√2≒340V。因此,升压电压VBULK需要被设定340V以上。
基于以上的动作描述,可以清楚地看出以下几点。
有源钳位开关Q2将存储在漏电感Lr中的能量充电到升压电容器CBULK1,并在向二次侧传输功率的过程中将其放电,从而不会耗散存储在漏电感Lr中的能量。此外,驱动开关Q1和有源钳位开关Q2始终处于ZVS模式,这显著降低了与开关相关的损耗和噪声。这些效果与有源钳位反激式的效果相同。
此外,由于二次侧开关节点电压LX2被整流二极管D1、整流二极管D2钳位,因此不会产生不需要的振铃。
另外,由于二次侧开关节点电压LX2的振幅为输出电压VOUT与二次侧基准电压SGND之间的电压,所以例如在输出电压为20V的情况下,振幅为20V,这比在有源钳位反激式中产生的100V~150V低大约1/5左右。因此,这些因素进一步降低了噪声。因此,图中未示出的降噪所需的元件是不必要的或者可以制成更小的,从而能够实现电源的小型化。
此外,由于整流二极管DACF所需的耐压为100V~150V,而整流二极管D1、整流二极管D2所需要的耐压为20V,因此,可以使用小型、低耐压、高速且廉价的特性高的器件。
另外,具有20V输出的有源钳位反激式的绕组比大致为NP:NS=5:1(参照非专利文献2第8页中的6.4节)。另一方面,在本实施例中,当升压电压VBULK设定为400V时,基于输出电压VOUT=升压电压VBULK×NS/NP,因此NS/NP=输出电压VOUT/升压电压VBULK=20/400,得到NP:NS=20:1。这意味着,当有源钳位反激和一次侧绕组的匝数相同时,二次侧绕组的匝数可以减少至1/4。例如,在有源钳位反激式电路中,如果一次绕组为20匝时,二次绕组为4匝。
另一方面,在本实施例中,如果一次绕组为20匝,则二次绕组可以将每匝并联缠绕4圈。即,二次侧绕组电阻为1/4×1/4=1/16,从而实现低损耗和高效率。或者,也可以通过将二次侧绕组1匝1并联,使变压器T1小型化。
如上所述,本实施例可以构成比有源钳位反激式更小型、高效率、低噪声的开关电源。
【实施例2】
接下来,使用图5来说明本发明实施例的不同电路配置。
实施例2与实施例1的不同之处在于,没有跨绝缘的反馈电路U2,而是由反馈电阻RFB1和RFB2代替。此外,整流二极管D1、整流二极管D2取而代之的是由同步整流开关Q3、同步整流开关Q4和同步整流开关控制电路U3,同步整流开关控制电路U4构成的理想二极管,除了槽路电容器CT11之外还追加了槽路电容器CT12。
通常,为了配置跨越绝缘体的反馈电路U2,需要光电耦合器和并联稳压器等半导体以及确保稳定性的RC网络。然而,如实施例1所述的,输出电压VOUT=升压电压VBULK×NS/NP,而且NS/NP是设计值,因此是已知的固定值。因此,如实施例所示,在NP:NS=20:1的情况下,如果将升压电压VBULK控制为400V,则输出电压VOUT为20V。
由此,如果不考虑变压器的绕组比偏差,则不需要从二次侧反馈,只要将升压电压VBULK作为反馈信号处理即可。通常,由于接收反馈信号的电路由低耐压元件构成,因此在图5中示出了通过反馈电阻RFB1和反馈电阻RFB2分压为不超过元件击穿电压的例子。由此,就不需要反馈电路U2,能够实现基板的小型化和低成本化。
另外,在实施例1中,整流二极管D1、整流二极管D2为二极管,因此在整流时产生正向电压Vf,并且发生正向电压Vf×二次侧整流电流ISEC的损耗。这对于转换器的总损耗是不可忽视的损耗。通过将整流二极管D1替换为同步整流开关控制电路U3和同步整流开关Q3,将整流二极管D2替换为同步整流开关控制电路U4和同步整流开关Q4,整流过程中的损耗可以作为同步整流开关Q3和同步整流开关Q4的导通电阻Ron×二次侧整流电流ISEC^2的损耗。
这同样适用于有源钳位反激式,但是在有源钳位反激式中,例如,输出电压为20V时需要大约100V~150V的元件耐压。然而,在本发明中,同步整流开关Q3、同步整流开关Q4可以是20V左右的元件耐压,并且可以使用小型、低导通电阻、高速且廉价的高性能器件。
另外,在实施例1中,由于仅在时段T2对输出电容器COUT1进行充电,所以非充电期间较长,输出电容器COUT1的充电电流变大。由于输出电容器COUT1是平滑电容器,因此需要数百uF,并且使用聚合物固体电解电容器。聚合物固体电解电容器的ESR(等效串联电阻)很大,电阻值从数十~数百mΩ,因此ESR造成的损耗不能忽视。
另一方面,在实施例2中,由于在输出电压VOUT与槽路电容器的电压VTANK之间追加了槽路电容器CT12,所以时段T1、T2中能够经由槽路电容器CT11、槽路电容器CT12向输出电容器COUT2流过谐振电流。
图6表示实施例1和实施例2中的输出电容器COUT1和输出电容器COUT2的输出电容电流ICOUT1和输出电容电流ICOUT2的比较波形。
在实施例2中,时段T1与实施例1同样地在对槽路电容器CT11充电的同时,通过槽路电容器CT12将谐振电流的一部分充电到输出电容器COUT2。另外,在时段T2中,在对槽路电容器CT12充电的同时,通过槽路电容器CT11将谐振电流的一部分充电到输出电容器COUT2。
从波形可知,在图6中,由于流过输出电容器COUT2的充放电电流变小,因此能够降低ESR引起的损耗。
另外,由于槽路电容器CT11、槽路电容器CT12是谐振电容器,因此它们的电容值可以很小,可以使用陶瓷电容器。陶瓷电容器的ESR与聚合物固体电解电容器相比非常低,只有几mΩ的量级。因此,能够降低损耗并获得更高的效率。
此外,因为可以通过减小充电/放电电流来减小在输出电压VOUT的每个开关频率处产生的脉动电压,所以可以减小输出电容器COUT2的电容。因此,能够进一步实现装置的小型化。
【实施例3】
已知可以通过使用反激式或有源钳位反激式作为PFC(功率因数校正电路)来配置单级PFC(参见非专利文献3)。
基于本发明的转换器同样可以配置单级PFC。仅是将实施例1或实施例2中的控制器变更为具有基于固定导通时间控制的功率因数校正功能的控制器或具有基于乘法器的功率因数校正功能的控制器。
图7显示了当实施例2中的控制器反馈电路U2是具有基于固定导通时间控制的功率因数校正功能时,功率因数校正动作期间的动作波形。另外,图8是表示图7中所示的时刻Tpeak(最大峰值)的放大波形。
如图7所示,可以看出,由于磁化电流ILm根据输入电压VIN而变化,因此相位差很小,功率因数得到校正。
在基于传统的反激式转换器的单级PFC中,为了使商用频率的两倍频率下产生的输出电压VOUT的脉动平滑,需要将输出电容器COUT1大型化。在基于本发明的转换器中,输出电压VOUT=升压电压VBULK×NS/NP,因此,为了使输出电压VOUT的脉动平滑,相当于使升压电压VBULK的脉动平滑。
升压电压VBULK的脉动通过升压电容器CBULK1被平滑。例如,如果配置具有相同的输出电压VOUT=20V的单级PFC,并且升压电压VBULK为400V,与基于传统反激式转换器的单级PFC相比,电容的能量是(400V/20V)^2=400倍。这意味着,与传统的单级PFC相比,在基于本发明的转换器中,仅需要升压电容CBULK1的1/400的电容来等效平滑输出电压的脉动。
另外,如果不是PFC,则输入电容器CIN1的电容不限于特定值。但如果是PFC的情况下,输入电容器CIN1的电容需要在不影响功率因数的范围内减小。
当使用反激式或有源钳位反激式作为PFC(功率因数校正电路)时,由于输入电容器CIN1的电容较小,所以输入电容器CIN1无法抑制ESD等浪涌,导致输入电压VIN升高。需要追加浪涌对策电路或选择具有能够耐受浪涌的元件耐压的器件,成为成本增加和尺寸变大的原因。
在基于本发明的转换器中,虽然同样需要减小输入电容器CIN1的电容,但由于浪涌引起的输入电压VIN的上升经由旁路二极管DIN1被钳位在具有大容量的升压电容器CBULK1上,所以不需要对策电路,无需提高元件耐压。
因此,在将本发明应用于PFC的情况下,可以不需要电容器的小型化或浪涌对策电路就能够实现小型化。
图中符号说明
VACACF,VAC 交流电源
BDACF,BD1 桥式二极管
CINACF,CIN1 输入电容器
U1ACF,U1 控制电路
U2ACF,U2 反馈电路
Q1ACF,Q1 驱动开关
Q2ACF,Q2 有源钳位开关
Cr 谐振电容器
TrACF,Tr 理想变压器
LmACF,Lm 磁化电感
LrACF,Lr 漏电感
T1ACF,T1 变压器
DACF,D1,D2 整流二极管
COUT1ACF,COUT1,COUT2 输出电容器
RLOAD1ACF,RLOAD1,RLOAD2 负载
VINACF,VIN 输入电压
VCr 谐振电容电压
VOUTACF,VOUT 输出电压
LX1ACF,LX1 一次侧开关节点电压
LX2ACF,LX2 二次侧开关节点电压
ILmACF,Ilm 磁化电流
ILrACF,ILr 谐振电流
ISecACF,ISec 二次侧整流电流
PGNDACF,PGND 一次侧基准电压
SGNDACF,SGND 二次侧基准电压
S100,S200 本发明的开关电源电路
CBULK1 升压电容器
DIN1 旁路二极管
VGS1 驱动开关控制信号
VGS2 有源钳位开关控制信号
VBULK 升压电压
CT1,CT11,CT12 槽路电容器
VTANK 槽路电容电压
ICOUT1,ICOUT2 输出电容电流
RFB1,RFB2 反馈电阻
Q3,Q4 同步整流开关
U3,U4 同步整流开关控制电路
Vf 二极管正向电压
ZVS 零电压开关
先行技术文献
【专利文献】
【专利文献1】日本专利第6643423号
【非专利文献】
【非专利文献1】Hari,A.,McCoy,B.,“High-Density Ac-Dc Power Suppliesusing Active-Clamp Flyback Topology”,Semiconductor Components Industries,LLC,2019October,2021-Rev.5 1Publication Order Number:TND6279JP/D.
【非专利文献2】Texas Instruments Inc.,“Zero-Voltage-Switching FlybackUsing UCC28780 Controller and UCC5304 Isolated Synchronous-Rectifier Driver”,July 2020.
【非专利文献3】Kali Naraharisetti,Janamejaya Channegowda,“Single StagePFC Flyback AC-DC Converter Design”,2020IEEE International Conference onElectronics,Computing and Communication Technologies,02-04July 2020.
【非专利文献4】Texas Instruments Inc.,“UCC28780 High Frequency ActiveClamp Flyback Controller”,SLUSD 12A–OCTOBER 2017–REVISED,February2018.

Claims (7)

1.一种开关电源电路,其特征在于:包括
变压器,其具有一次绕组和二次绕组;
驱动器开关,其用于驱动所述变压器;
有源钳位开关,当所述驱动器断开时钳位一次侧开关节点;
大容量电容器,其用于释放钳位能量;
第一整流器、第二整流器;
槽路电容器、输出电容器;
反馈电路,其根据输出电压输出反馈信号;以及
控制电路,其根据所述反馈信号控制所述驱动器开关和所述有源钳位开关;
其中,所述驱动器开关和所述有源钳位开关的一端与所述大容量电容器的正极和负极的一端连接,
所述驱动器开关和所述有源钳位开关中的另一端与所述大容量电容器的正极和负极中的另一端连接,
所述有源钳位开关钳位一次侧开关节点,
所述第一整流器和所述第二整流器与所述输出电容器的正极和负极的一端连接,所述第一整流器和所述第二整流器中的另一端与所述输出电容器的正极和负极的另一端连接,
所述第一整流器或所述第二整流器钳位二次侧开关节点,
所述二次绕组的一端与所述二级侧开关节点连接,另一端与所述槽路电容器连接,输出电压是将所述大容量电容器电压乘以所述二次绕组的匝数与所述一次绕组的匝数之比而获得。
2.如权利要求1所述的开关电源电路,其特征在于:
权利要求1所述的槽路电容器是由第一槽路电容器和第二槽路电容器串联连接构成的串联槽路电容器,其中,
所述串联槽路电容器的正极与所述输出电容的正极连接,
所述串联槽路电容器的负极与所述输出电容的负极连接,
所述串联槽路电容器的中点与所述二次绕组的另外一端连接。
3.如权利要求1所述的开关电源电路,其特征在于:
所述控制电路控制所述有源钳位开关导通,直至所述变压器积累足够能量以供所述驱动器开关以执行零电压切换(ZVS)。
4.如权利要求2所述的开关电源电路,其特征在于:
所述控制电路控制所述有源钳位开关导通,直至所述变压器积累足够能量以供所述驱动开关以执行零电压切换(ZVS)。
5.根据权利要求1~4中任一项所述的开关电源电路,其特征在于:
所述反馈电路监测具有与所述输出电压对应的所述大容量电容的电压,并将该电压传输至控制电路。
6.根据权利要求1~4中任一项所述的开关电源电路,其特征在于:
所述第一整流器和所述第二整流器分别是晶体管。
7.根据权利要求1~4中任一项所述的开关电源电路,其特征在于:
所述开关电源电路具有功率因数校正功能。
CN202311448280.8A 2022-11-07 2023-11-02 开关电源电路 Pending CN117997128A (zh)

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US6882548B1 (en) * 2003-02-24 2005-04-19 Tyco Electronics Power Systems, Inc. Auxiliary active clamp circuit, a method of clamping a voltage of a rectifier switch and a power converter employing the circuit or method
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