BL-PFCinSMPS

nullPower Factor Correction in Switched-Mode Power Supplies 开关电源中的功率因数校正Power Factor Correction in Switched-Mode Power Supplies 开关电源中的功率因数校正安 森 美 半 导 体 Outline 纲要Outline 纲要Introduction and Definitions 概述和定义 Power Factor vs. Harmonic Distortion 功率因数和谐波失真 Power Factor Correction Categories 功率因数校正类别 No PFC, Passive PFC and Active PFC 无PFC，无源PFC和有源PFC PFC Controller Types PFC控制器类型 Discontinuous Conduction 不连续导电 Critical Conduction 临界导电 With Multiplier 有乘法器 Without Multiplier 无乘法器 Follower Boost 跟随升压 Continuous Conduction 连续导电 Summary Why the Interest in Power Factor Correction? 为什么对功率因数校正感兴趣？Why the Interest in Power Factor Correction? 为什么对功率因数校正感兴趣？Ac-powered electronic products with diode-capacitor inputs have non-sinusoidal input current. 具有二极管-电容器输入的交流电源电子产品，有非正弦输入电流。 Current flows only at the peaks of the input sine wave to recharge the capacitor. 只在输入正弦波的峰值处有电流流通，重新对电容器充电。 This current has a high rms value. 该电流具有高的rms值。 This causes stress on wiring. 这对配线造成压力。 Sometimes this trips circuit breakers. 有时导致断路器跳闸。 Higher current raises the costs of generating and distributing electricity. 较大的电流提高了发电和配电的成本。 In Europe and some other parts of the world (not yet the US), the governments mandate “clean” (low-distortion) input current. 在欧洲和世界的其他一些地方（不包括美国），政府规定要使用“清洁的”（低失真）输入电流。 Most regulations are derivatives of the International Electrotechnical Commission’s IEC 1000-3-2 standard. Europe’s version is EN1000-3-2. 大多数规定是从国际电工委员会的IEC 1000-3-2 标准引申出来的。欧洲的版本是EN1000-3-2。IEC1000-3-2IEC1000-3-2Applies to single or 3-phase equipment intended to be connected to 220/380 V, 230/400 V and 240/415 V systems operating at 50 Hz or 60 Hz. Applies up to 16 A per phase. 适用于连接至工作频率为50 Hz 或60 Hz的220/380 V、230/400 V以及 240/415 V 系统的单相或3相设备。每相的电流可高达16A。 Products with input power of less that 75 W are excluded. 不包括输入功率低于75W的产品。 Note the absence of lower-voltage (115 V) systems! 注意不包括低压（115V）系统！ Class A: Balanced 3F equipment and all others, except that stated in one of the other classes. A类：平衡3相设备和其他类别中未列出的所有设备。 Class B: Portable tools. B类：便携式工具。 Class C: Lighting equipment, including dimming devices. C类：照明设备，包括调光设备。 Class D (changed by Amendment 14): Equipment of 600 W or less, of the following types: D类（由修正案14修改）：600W或以下的设备，包括以下类型： Personal computers and personal computer monitors 个人电脑和个人电脑显示器 Television receivers 电视接收器 This list may expand in the future! 本列表将来可能会扩展！ The Result of These Regulations 这些规定的结果The Result of These Regulations 这些规定的结果Personal computers & monitors, plus TV sets, sold in many countries outside the USA must conform to Class D. 个人电脑和显示器以及电视机在美国以外的很多国家销售时，必须遵守D类。 Class D harmonic limits are proportional to input power. D类谐波限制与输入功率成正比。 Most other products fall into Class A. 大多数其他产品归入A类。 Class A harmonic limits are fixed. A类的谐波限制是固定的。 Odd harmonic limits coincide with the 600 W Class D limits. Limits are stated out to 40th harmonic. 奇次谐波的限制与600W的D类限制相同。限制规定到第40次谐波。 Odd: 3rd harmonic <2.3 A, 5th harmonic <1.14 A ...decreasing to 39th 奇次：3次谐波<2.3 A，5次谐波<1.14 A ……递减到39次 Even: 2nd harmonic: <1.08 A, 4th harmonic <0.43 A ...decreasing to 40th 偶次：2次谐波： <1.08 A，4次谐波<0.43 A ……递减到40次 Harmonic distortion is directly related to Power Factor (PF) as will be shown in the slides that follow. 谐波失真与功率因数（PF）有着直接的联系，我们将在下面说明。 Power Factor --- The Whole Story 功率因数——完整的介绍Power Factor --- The Whole Story 功率因数——完整的介绍By definition: 根据定义：Where: 其中： Real Power = The average of the product of voltage and current. 有功功率＝电压与电流乘积的平均值。 Over a specified time interval, the voltage and current at each increment of time are multiplied together (indicating the actual power during that increment). Then, the average is computed over the specified interval to arrive at the average real power. 在指定的时间段内，每一个时间增量中的电压与电流相乘（表示该时间增量中的实际功率）。然后计算特定时间段中的平均值，得到平均有功功率。 The “increment of time” must be short, compared to variations in the voltage and current. 与电压和电流的变化相比， “时间增量”必须很短。 Apparent Power = The product of the rms voltage and rms current. 视在功率＝rms电压和rms电流的乘积。 Again, this applies to the specified time interval. 同样的，这适用于特定的时间段。 In periodic waveforms such as those appearing on our “mains,” the specified interval is usually one period (a “cycle” of the 60 Hz wave). 在周期波形中，例如我们的“主干线”中的波形，该特定时间段通常是指一个周期（6Hz波形的一次“循环”）。Apparent Power 视在功率Real Power 有功功率PF=Assuming a Clean, Sinusoidal Voltage: 假设一个干净的正弦波电压：Assuming a Clean, Sinusoidal Voltage: 假设一个干净的正弦波电压：And: 并且： I1 = The fundamental of the ac line current. I1 =交流线路电流的基波。 Irms = The ac line current. Irms =交流线路电流。 Cosq = The phase angle between the input voltage and the input current fundamental. Cosq =输入电压和输入电流基波之间的相位角。 When current and voltage are in phase (cosq = 1), PF and Kd are the same. 当电流和电压同相（ cosq = 1 ）时，PF和Kd相等。 All of this applies only when the input voltage is a clean sinusoid (the usual case). 所有这些只在输入电压为干净的正弦波时（通常情况）适用。 其中：失真系数What About Total Harmonic Distortion (THD)? 关于总谐波失真（THD）What About Total Harmonic Distortion (THD)? 关于总谐波失真（THD）THD is defined as the root-sum-of-squares function (rms) of the harmonics higher than or equal to 2 over (divided by) the fundamental: THD定义为2次或2次以上谐波的平方和的平方根（rms）除以基波：因为：通过代换，可以得到：所以及因为：PR = Kd· cos.所以当基波的电流与电压同相时（cos=1），就有：当THD=0.1（10%）时，PF = 0.995Power Supply Input Without PFC 无PFC的电源输入Power Supply Input Without PFC 无PFC的电源输入Input current flows only at the peaks of the input voltage wave. 输入电流仅在输入电压波形的峰值处流通。 As a result, the rms (heating value) of the current is much higher than without the capacitor. 因此，电流的rms（热值）比无电容时大得多。Output Voltage 输出电压Without Capacitor 无电容Ac Input (Voltage)交流输入（电压）Output Voltage 输出电压Rectifier Current 整流电流CRInput Current输入电流Performance of a Non-PFC Power Supply (Meets IEC1000-3-2 Class A Under ~120 Watts) 无PFC电源的性能 （满足IEC1000-3-2 A类低于~120 瓦的限制）Performance of a Non-PFC Power Supply (Meets IEC1000-3-2 Class A Under ~120 Watts) 无PFC电源的性能 （满足IEC1000-3-2 A类低于~120 瓦的限制）Top trace: Input voltage 上面的曲线：输入电压 Bottom trace: Input current 下面的曲线：输入电流Amplitude of input current harmonics, relative to the fundamental. 输入电流谐波的幅度，相对于基波。0.00%20.00%40.00%60.00%80.00%100.00%13579111315171921Harmonic Number 谐波次数Performance of a PFC Power Supply 有PFC电源的性能Performance of a PFC Power Supply 有PFC电源的性能0%20%40%60%80%100%13579111315171921Harmonic Number 谐波次数Top trace: Input voltage 上面的曲线：输入电压 Bottom trace: Input current 下面的曲线：输入电流Amplitude of input current harmonics, relative to the fundamental. 输入电流谐波的幅度，相对于基波。PFC: With, Without, and Halfway In-Between 有PFC，无PFC，以及一半在中间PFC: With, Without, and Halfway In-Between 有PFC，无PFC，以及一半在中间Input voltage 输入电压 Input current without PFC 无PFC的输入电流 Input current with passive PFC 具有无源PFC的输入电流 Input current with active PFC 具有有源PFC的输入电流 Passive PFC: A line-frequency inductor, placed in series with the input, shapes the input current. 无源PFC：一个工频电感，与输入串联，为输入电流整形。Harmonic Content of the Three Versions of PC Supplies 三种版本PC电源的谐波含量Harmonic Content of the Three Versions of PC Supplies 三种版本PC电源的谐波含量These are PC supplies, so must conform to Class D limits (most stringent). 这些是PC电源，所以必须遵守D类限制（最为严格）。0.0010.0100.1001.00010.0003132333Harmonic Number 谐波次数Amplitude, mA per W 幅度, mA / WEN61000-3-2 Limit EN61000-3-2限值Without PFC 无PFCWith Passive PFC 具有无源PFCWith Active PFC 具有有源PFCPassive PFC in a 250-W PC Power Supply 250W PC电源中的无源PFCPassive PFC in a 250-W PC Power Supply 250W PC电源中的无源PFCDisadvantage: A two-position line switch is needed for wide-range input. 缺点：对于大范围输入需要一个2位线路开关。 230-V position: Both halves of inductor are used. Full wave. 230-V 位：使用两个半电感。全波。 115-V position: Left halves of inductor & bridge are used. ½ wave. 115-V 位：使用左半电感和桥。半波。 In both cases, nominal output voltage is 325 Vdc. 在两种情况下，额定输出电压都是325V直流。1 M0.1230 Vac115 Vac325 Vdc toForwardConverter 325V直流至正激变换器+-470.0047.00474700.22.022.022.01PFC Inductor PFC电感Common-ModeInductor(L3) 共模电感 (L3)Differential-Mode Inductor (L2)差模电感 (L2)Inrush Current Limiter (Thermistor) 涌流限制器 （热每电阻）Passive PFC in a 250-W PC Supply 250W PC电源中的无源PFCPassive PFC in a 250-W PC Supply 250W PC电源中的无源PFCHere, the PFC circuit has been replaced by a line-frequency inductor. It’s big (approx. 5 cm cube), heavy, and cheap. 此处PFC电路被一个工频电感所取代。它体积大（约为.5立方厘米）而重，但价格低廉。1.0”Here’s A Really Simple PFC: The Discontinuous Flyback Converter 一个简单的PFC：不连续反激变换器Here’s A Really Simple PFC: The Discontinuous Flyback Converter 一个简单的PFC：不连续反激变换器Flyback must run in discontinuous mode for the average current to be a replica of the voltage (peak current is high). 反激必须在不连续模式下工作，使平均电流成为电压的复制（峰值电流很高）。 Pulse width must not change during the half-cycle of input voltage. 脉冲宽度在输入电压的半周期中不得改变。 Ac Input (Voltage)交流输入（电压）PWM Control控制Locus of current peaks 电流峰值的轨迹Average of each triangle 每个三角的均值Average Current 平均电流Critical Conduction (“Transition”) Mode is Better 临界导电（“过渡”）模式更佳Critical Conduction (“Transition”) Mode is Better 临界导电（“过渡”）模式更佳Switch is turned on again as soon as the inductor current decays to zero. 当电感电流减至零时，开关立即再次打开。 Average current is always half the peak amplitude. 平均电流总是峰值幅度的一半。 Boost diode turns off naturally. 升压二极管自然截止。 Switch turns on into zero current. 开关接通至零电流。 Low switching losses, but high conduction loss (compared to continuous conduction mode). 低开关损耗，但是导电损耗高（与连续导电模式相比）。 Inductor design is a real challenge, due to high ac current and flux. 电感的设计是一大挑战，因为交流电流和磁通都很大。Critical Conduction Mode Controller 临界导电模式控制器Critical Conduction Mode Controller 临界导电模式控制器Multiplier is required, but the IC is relatively simple. 乘法器是需要的，但是IC相对比较简单。 ON’s MC33262 and its competitors. Good, low-distortion input current. 安森美的MC33262 及其竞争产品。良好的低失真输入电流。Error Amp 误差放大器2.5 VCurrentControlOutShapingNetwork 电流整形网络RLogic 控制逻辑ZeroCurrent 零电流Output 输出Input 交流输入Multiplier 参考乘法器ReferenceCritical Conduction Mode Without the Multiplier 无乘法器的临界导电模式Critical Conduction Mode Without the Multiplier 无乘法器的临界导电模式On-time (rising portion of Iinductor) is fixed. 接通时间（ Iinductor 的上升阶段）是固定的。 Rising slope is proportional to Vin. 上升斜率与Vin成正比。 Falling slope is proportional to (Vout – Vin). 下降斜率与(Vout – Vin)成正比。 As in the previous case, the next pulse starts as soon as the current in the inductor decays to zero. 如前例一样，下一个脉冲在电感电流减至零时立即开始。 Inductor current, of course, is synonymous with the input current. 电感电流当然与输入电流同步。Frequency is variable. At 60 kHz, there are 500 cycles within each half-cycle envelope. 频率是可变的。在60 kHz下，每个半周期的包络中有500个周期。 Current is not a perfect sine shape, but well within IEC limits. 电流不是完美的正弦形状，但是能够满足IEC的限制条件。Critical-Mode Controller Without Multiplier (MC33260) 无乘法器的临界式控制器（ MC33260 ）Critical-Mode Controller Without Multiplier (MC33260) 无乘法器的临界式控制器（ MC33260 ） Output is converted to a current. 输出被转化为一个电流。 a. This current is squared, and fed to the one-shot ramp capacitor to determine the slope. a. 这个电流是方形的，并且被馈入到单锯齿波电容器中，确定斜率。 b. The current is compared to a reference current, then converted to Vcontrol. b. 这个电流与一个参考电流相比较，然后转化为Vcontrol。 c. The ramp and Vcontrol are applied to the PWM comparator to determine the length of the drive pulse to the boost FET. c. 锯齿波和Vcontrol被加到PWM比较器，以确定升压FET驱动脉冲的宽度。 d. When the current decreases to zero, the cycle starts over again. d. 当电流减至零时，循环重新开始。One-shot单脉冲RectCTPWMZero CurrentDetection 零电流controlSense 电流检测CurrentVRect acCOutput 输出Programmable可编程2oVIFollower Boost Mode (MC33260) 跟随升压模式（ MC33260 ）Follower Boost Mode (MC33260) 跟随升压模式（ MC33260 ）Output voltage is not fixed, but rather “follows” the input. 输出电压不是固定的，而是“跟随”输入变化。 Controller operates in Critical Conduction Mode. 控制器在临界导电模式工作。 Stresses on inductor, FET, diode and capacitor are reduced. 电感、FET、二极管和电容器上的应力减少。 Cost and space are significantly reduced. 成本和空间明显减少。 Good news / bad news: 好消息/坏消息： Less holdup time, because of lower V on storage cap. 保持时间较短，因为存储电容上的电压较低。 Many applications don’t require holdup time. 很多应用不需要保持时间。The Original---Unitrode (TI) UC3854 (Continuous Mode) 新颖的Unitrode (TI) UC3854 （连续模式）The Original---Unitrode (TI) UC3854 (Continuous Mode) 新颖的Unitrode (TI) UC3854 （连续模式）Continuous conduction minimizes conduction and mag. losses. 连续导电减小了导电损耗和磁损耗。 Diode turn-off losses are a challenge. 二极管截止损耗是一个难点。负载交流输入PWM控制乘除以平方New From ON Semiconductor: The NCP1650 Controller 安森美半导体的新产品： NCP1650控制器New From ON Semiconductor: The NCP1650 Controller 安森美半导体的新产品： NCP1650控制器ReferenceMultiplier 参考乘法器Rac2R7Oscillator 振荡器Network 电流整形网络ShapingCurrentAmplifier 电流检测 放大器SenseCurrentLogic 控制逻辑ControlComp 环路比较LoopFB/SDRac14 VError Amp 误差放大器RectOutput 输出5DRdc1Input 交流输入VQ1outCshuntRRectVoltage Loop Error Amplifier 电压环路误差放大器Voltage Loop Error Amplifier 电压环路误差放大器The NCP1650 uses a “window” approach in responding to transients. If the input to the voltage feedback error amplifier goes outside of the window (+6% or –8%) the output drive steps up from 20 uA max. to 250 uA. NCP1650使用“窗口”的方法对瞬态响应。如果电压反馈误差放大器的输入超出了窗口（ +6% 或 –8% ），输出驱动从20 uA 跃升至最大250 uA。4.20 V4.24 V4.00 V3.80 V3.68 V250 uASource 源20 uA250 uA20 uASink 漏Output Current 输出电流Input Voltage (pin 6) 输入电压（管脚6）FB/SD6ErrorAmp 误差放大器3.68 V250 uA20 uAmax4.24 V250 uA最大 20 uAAbout Transient Response of a PFC Stage 关于PFC级的瞬态响应About Transient Response of a PFC Stage 关于PFC级的瞬态响应Positive excursions must not trigger OVP circuits. 正向突变不应触发OVP电路。 Negative excursions must not interrupt the output converter. 负向突变不应阻断输出变换器。 The rate of change at the output of the PFC stage is usually much slower than the response time of the output converter’s feedback loop. PFC级输出的变化率往往比输出变换器反馈环路的响应时间慢得多。 Therefore, unless the output of the PFC goes outside the boundaries above, transient performance of the PFC is not important. 因此，除非PFC的输出超出了上面的界限，PFC的瞬态性能并不重要。Operation of the Switched-Mode Multiplier 开关式乘法器的工作Operation of the Switched-Mode Multiplier 开关式乘法器的工作Pulsed current source. 脉冲电流源。 Input “a” controls the current. 输入“a”控制电流。 Input “p” controls the duty ratio of the pulses. 输入“p”控制脉冲的负荷比。 Average current is a · p. 平均电流是a · p。 Pulse waveform is derived from the PWM clock. 脉冲波形是从PWM时钟得到的。 Not a fast multiplier! 不是快速乘法器！ Not a fast loop! 不是快速环路！ Good idea! 好主意！ Very repeatable, stable, tight tolerance. 可重复、十分稳定、紧公差。InputOutputInput p 输入PRampInvertingV to I ConverterInput aNI InputNI输入输出倒相输入V-I 变换器锯齿波输入anullSpecifications are entered, component values are suggested, then chosen by the designer. Then, the software analyzes component stresses at any chosen set of input and output conditions. 输入规格就可得到建议的元件值，然后由设计者选择。随后，该软件分析元件在各种选定的输入和输出组合条件下受到的应力。Design Aid (Sample) 设计帮助（范例）Limits限值Pomax=1200wVinmax=260vrmsVinmin=85vrmsVo =400VDCfswitch =100kHzL =300uHSuggest 建议Lmin =34uHLmax =168uHEvaluation 评估值Pout =1000wVi =120vrmsfLINE = 60HzEffic = 0.95Pin =1053wT =10usLimits info should not change for a given design. Evaluation data may be changed as desired for various line & load conditions. 对于给定设计的限制信息不应改变。评估数据可能因所需的线路和负载条件不同而改变。度纹波电流峰-峰值与角度的关系纹波电流（Ap-p）Based on the Designer Input, Parts are Suggested 根据设计者的输入，推荐所需的元件Based on the Designer Input, Parts are Suggested 根据设计者的输入，推荐所需的元件NCP1650 Design Aid NCP1650设计帮助Provided by ON Semiconductor 由安森美半导体提供rFor a system with the following specifications: 对于具有以下规格的系统：Pomax = 1200wattsVinmax = 260vrmsVinmin = 85vrmsfLINE = 60HzfSwitch =100kHzVout = 400voltsh =0.95L =300uHThe following parts are required2: 需要以下的元件2：Cout1 =560uFacscale =0.010divider ratio 分压比C2 =0.1uFRShunt = 0.007OhmsC3 =50nFR3 = 1,500OhmsC4 =5nFR7 =680OhmsC7 =47uFR8 =7,500OhmsC8 =22uFR9 =62,000OhmsC9 =5uFR10 = 10,000OhmsC11 =4.7nFR13 = 56kOhmsCT =1800pFNotes: 注意： Ripple current calculations for input and output capacitors are plotted on sheet 3a. 输入和输出电容的纹波电流的计算是在3a页上绘出。 2. These component values are a recommended starting point, however, ON Semiconductor does not guarantee that the circuit will meet all specifications. Normal troubleshooting and adjustments may be necessary. 这些元件的取值仅为建议的起点，但安森美半导体不保证电路满足所有规格。必须进行正常的故障检测和调整。NCP1650 Design Parts List NCP1650设计元件列表Component Stress Analysis (FET Loss) 元件应力分析（FET损耗）Component Stress Analysis (FET Loss) 元件应力分析（FET损耗）Operator enters FET parameters; software calculates stress. 操作员输入FET参数；软件计算应力。 Power Switch Losses 电源开关损耗RDSon 1OhmsAverage FET losses 平均FET损耗19.33 WTurn on time (tf)接通时间80ns Peak voltage = 峰值电压=400VTurn off time (tr)关断时间50nsPower FET Losses 功率FET损耗0.05.010.015.020.025.030.035.040.004590135180Angle (deg) 角度 (deg)Losses (watts) 损耗（W）What’s Next? 下一步做什么？What’s Next? 下一步做什么？Clean input current is not a passing fad. 干净的输入电流不是转瞬即逝的。 Standards are getting tougher. 标准越来越严格。 More countries are adopting them. 越来越多的国家采用它们。 It’s up to us to provide clean power cheaper, and more efficiently. 我们应该提供更加廉价和高效的干净电源。 Energy conservation: Part of our job as the Power Efficiency Leader! 节能：作为节电王，节能是我们工作的一部分！ Efficiency at standby. 待机的效率。 Efficiency at normal loads. 正常负载下的效率。 Latest-generation controller ICs are paving the way. 最新一代的控制器IC正在为其铺路。 At ON Semiconductor, we are developing new IC controllers that go beyond the traditional continuous and critical conduction modes. 在安森美半导体，我们正在开发能超越传统的连续和临界导电模式的新的IC控制器。 For a copy of this presentation, email chuck.mullett@onsemi.com. 要这个演示的拷贝，请发电子邮件到chuck.mullett@onsemi.com。