开关电源的电磁兼容设计技术.pdf

开关电源电磁兼容设计的几个问题开关电源电磁兼容设计的几个问题Some keySome key EMC design techniques in SMPSEMC design techniques in SMPS报告人：和军平（报告人：和军平（Dr.））Jun,Jun, 2626, 20, 201010hejunping@Shenzhen CityShenzhen CityCPSSC一. 开关电源主要EMC性能及其改善技术 二. 开关电源EMI滤波器的协调设计 三. 降低EMI发射的抖频参数设计 四. 温升引起的发射波动及改善 五. 瞬态过电压抑制设计的要点 六. 结束语内容内容JunJun, , 2626, 20, 2010 10 HejunpingHejunpingFlyback total SMPSLISNLGNEMI receiver50 Ohm50 Ohm50uH50uH0.1uF0.1uF传导测试测试传导测试测试一. 开关电源主要EMC性能与设计技术CPSSCCPSSC220μFL1 MRloadD10.47uF450uHInput cableOutput cableicm1icm2PFCSMPS80cmChamber辐射发射测试辐射发射测试EMI receiverJunJun, , 2626, 20, 2010 10 HejunpingHejunpingCPSSCCPSSCESD测试测试JunJun, , 2626, 20, 2010 10 HejunpingHejunpingCPSSCCPSSC信号电缆用的耦合解耦网络信号电缆用的耦合解耦网络接电网接辅助设备EUT与发生器或耦合器之间的电缆小于2米接电网接辅助设备EUT与发生器或耦合器之间的电缆小于2米保护地线要能够承受浪涌电流保护地线要能够承受浪涌电流雷击浪涌测试雷击浪涌测试FilterTopologyControlActivePassiveDrive CircuitSoft SwitchingSnubberFrequency modulationForwardFeedbackBalancingEMI ReductionStructureshieldingGroundingEMI Reduction Techniques for Power Electronic SystemsEMI Reduction Techniques for Power Electronic SystemsJunJun, , 2626, 20, 2010 10 HejunpingHejunpingCPSSCCPSSCTopologies :How to design the filter in a short design cycle?& How to improve the filter performance?二. 开关电源EMI滤波器的协调设计JunJun, , 2626, 20, 2010 10 HejunpingHejunpingCPSSCCPSSCInput Filter DesignImprove the Design Program( 1MHz )L/NGLlineLlineInput FilterNoise SourceOutput FilterChassisChassisGroundGroundCS_GL LCM_OutCM_Out21L/NGLlineLlineInput FilterNoise SourceChassisChassisGroundGroundCS_GOutput FilterC CY_OutY_Out21ZLCM_Out 4ββ=4fc=65kHz fm=200HzAmplitude reduction [dB]JunJun, , 2626, 20, 2010 10 HejunpingHejunpingCPSSCCPSSCfc=65kHz0.11101002520151050fm=100Hzfc=100kHz0.11101002520151050ifm=200Hz0.11101002520151050fm=100Hz0.11101002520151050ifm=200Hz0.11101002520151050fm=500Hz0.11101002520151050fm=500HzAmplitude reduction [dB]tri exp sinβThe reduction is only the function of βJunJun, , 2626, 20, 2010 10 HejunpingHejunpingCPSSCCPSSCEMI Receiver’s Effect on FMIF filter has a resolution bandwidth RBW, when spectral components closer in frequency than RBW of IF filter will create a beat noteAV detector takes an envelope detected signal and passes it through a low-pass filterThe most impotent parts in EMI receiver’s model are intermediate- frequency (IF) filter and detectorAV detectorIF filterJunJun, , 2626, 20, 2010 10 HejunpingHejunpingCPSSCCPSSCThe equivalent low pass approximation of IF filter is defined as below:Equivalent IF Filter()9kHzB,B2πωωω*2)IF(66022 02 02 0=∗=⎥ ⎦⎤ ⎢ ⎣⎡++=ωωωj1.10401.10400.51f [Hz]IF(w)9kHz1.10401.10400.51f [Hz]IF(w)9kHz12505f [kHz]sin 2 π⋅k⋅t ⋅()sin 2 π⋅2⋅k⋅t ⋅π8−⎛⎜⎝⎞⎟⎠+Spectrum of the signal output of IF filterSpectrum of signal:Amplitude [dB]Resolution bandwidth (RBW) of IF filter is 9kHzJunJun, , 2626, 20, 2010 10 HejunpingHejunpingCPSSCCPSSCEMI Receiver’s ModelV(t)Vd(t)Vq(t)VIF(t)V(t)’s frequency response of EMI analyser at frequency of “f”)(ωIF)(ωIF∫02. 00)(02. 01dttVIF22)()(tvqtvd+)2cos(2tf ⋅⋅π)2sin(2tf ⋅⋅πJunJun, , 2626, 20, 2010 10 HejunpingHejunpingCPSSCCPSSCRBW of EMI Receiver and fmWhen fm>RBW , the peak amplitude reduction is only the function of βWhen fm RBW, the lower fm the larger reductionJunJun, , 2626, 20, 2010 10 HejunpingHejunpingCPSSCCPSSC• ADP-65JP: 65W flyback adapter, PWM controller is DAP008• DAP008 is Delta’s specific device ordered from ON Semi, it has built-in frequency jitter for lower EMI• Parameters of jitter in DAP008– Δfpk=3kHz– fm =100HzJunJun, , 2626, 20, 2010 10 HejunpingHejunpingCPSSCCPSSC• In order to keep the second-order harmonic of the noise out of the conducted EMI measurement range (0.15-30MHz), Δfpk has to be limit as:• Another limit on Δfpk is the minimum operating frequency of the power supply • Δfpk is slected about 4kHz, and fm is selected equal to1kHzkkkB915065222−<×+25 . 5242mm pkfkfBf−<−=ΔmpkffB⋅+Δ⋅⋅=) 12(22}B2130kHz65kHzJunJun, , 2626, 20, 2010 10 HejunpingHejunpingCPSSCCPSSCThe EMI noise reduction is about 10dB with AV detectorJunJun, , 2626, 20, 2010 10 HejunpingHejunpingCPSSCCPSSCLC温度的影响fZ0Normalfact f0T risef0idealf0居里点T riseZJunJun, , 2626, 20, 2010 10 HejunpingHejunpingCPSSCCPSSC 四. 温升引起的发射波动及改善瞬态干扰对设备的威胁瞬态干扰对设备的威胁电快速脉冲浪涌静电放电静电放电电源端口信号端口浪涌电快速脉冲静电放电JunJun, , 2626, 20, 2010 10 HejunpingHejunpingCPSSCCPSSC五. 瞬态过电压抑制设计的要点瞬态干扰抑制器件瞬态干扰抑制器件浪涌电压浪涌电压压敏电阻压敏电阻瞬态抑制二极管瞬态抑制二极管气体放电管气体放电管2205001000钳位不紧电流容量不大有跟随电流钳位不紧电流容量不大有跟随电流JunJun, , 2626, 20, 2010 10 HejunpingHejunpingCPSSCCPSSC气体放电管的跟随电流气体放电管的跟随电流跟随电流跟随电流• 寄生电容小寄生电容小• 电流容量大电流容量大不可用在直流的场合！不可用在直流的场合！JunJun, , 2626, 20, 2010 10 HejunpingHejunpingCPSSCCPSSC多级浪涌抑制电路多级浪涌抑制电路V1、V2= 额定工作电压I2= 第二级额定峰值电流V2≥V0+ 电压偏差2V1 ≥V2+ 电压偏差1+电压偏差2ΔV =V1MAX- V2MINZ ≥ ΔV / I2PV1V2 V0MAX浪涌一级 二级VV2V1V0Z ΔVI2PJunJun, , 2626, 20, 2010 10 HejunpingHejunpingCPSSCCPSSC地线反弹与对策地线反弹与对策设施地设备参考地 VGVZ +VGVZ若电流为若电流为5kA，地线阻抗为，地线阻抗为0.5Ω，则反弹电压达到Ω，则反弹电压达到2500V !JunJun, , 2626, 20, 2010 10 HejunpingHejunpingCPSSCCPSSC六. 结束语1：开关电源EMI滤波器设计需要综合考虑输入、输出 侧干扰的传播。

2：抖频需要考虑EMI接收机的带宽，使抖频参数合。