关于开关电源仿真的在线问答
1. 能否介绍一下变压器的建模？
If you want to simulation the transformer you must know the primary inductor value and secondary inductor and using the K factor connect the two wire. you can change the coupling factor K .e.g 0.99 for simulation it. Detail you can see the presentation files page 12.
2. 开关电源的最优化的仿真主要有那些内容
It is include the average simulation and switched simulation Average simulation is used to measure the phase and gain margin and the switched simulation is using to simulated the detail switch waveform.
3. PSPICE与Saber比较，您感觉谁更适合电源仿真？
PSpice is a general purpose simulator and the Saber is a system level simulator only. PSpice can help you to investigate the circuit performance down to details.
4.能否解释一下为什么平均模型不能分析电流环的原因，谢谢
This is related to the internal structure of model. Dr. Ridley has provided an average model that work for both voltage and current loop. However this is a AC small signal model that cannot calculate bias point and predict transient performance.
5. 在采用开关模型仿真的时候经常会遇到不收敛的情况，请问吴先生怎样才能很好的解决这个问题？
The convergence problems usually happen in SMPS simulations. There are several methods for solving this problem. The transient simulation time step can increase. The large number of simulation steps in each time step can avoid in some difficult point.
The GMIN optin in the option can be used for DC bias point to solve the convergence problem.
Some other option (i.e. ITL4=1000) will affect the tolerance of the simulation. This should be carefully considered in your design.
6. Pspice能否对电源的保护功能如过流过压过热保护等进行仿真模拟？效果如何？
Pspice simulation can also include the over current proctection over voltage protection. These functions is similar to soft-start functions and other functions of the controller and SMPS. But the thermal effect usually does not be contained in the this level simulation. Except this thermal effect. Other protection functions can be simulated effectively.
7. 开关电源中最难设计、又最难调试的是高频变压器 Pspice在这方面能发挥多大作用？这套软件是否只能对安森美器件有用?软件哪里有提供？
Yes you are right. If there is no pspice circuit to help you doing simulation. You will waste a lot of time to build a breadboard for testing. PSpice is a kind of circuit simulation that you can use computer to simulate your circuit. And it nevers blows out your circuit whether you put any component value on it.
For designing the high switching frequency converter. You can refer to page 12 of the slide. First you add a ideal transformer on it. And then choose the primary magnetizing inductance of the transformer with its" leakage. Then combine with the pwm model and other components. Then you can simulate your circuit. After finished the simulation you can click on the probe icon to add some probe on the node to see the voltage current. By looking the waveform. so you can modify the components value to make your design as your expection.
Pspice is not the only software for Onsemi Parts. You can click on the link http://www.cadencepcb.com/products/pspice/
and choose the student evaluation. This is free version. Of course there are limitation of this version. Also you can buy a full version of PSpice.
8.你好，请问如何缩短模拟时间和在运算过程成不收敛的情况一般有那些？谢谢
The simulation time can be shorten by many methods. If the model is a switching model the soft-start can be omitted. So the simulation time can be shorten for simulating the steady state. The averaging model is developed for shorten the simulation. The convergence problems also can be solve setting ITL4 ITL5 and etc option.
9.我在做Pspice时，经常出现无法继续，WHY?
It is because the input parpameter is not correct. you can try to set some init condition e.g in capactor and inductor value for improve the converage problem.
10.在采用开关模型进行仿真的时候，经常会遇到不收敛的情况，请问怎样才能很好的解决这个问题？
The convergence problem is a great problem. The convergence of transient simulations can be solved by increasing the time step of the simulation. In the bias point simulation GMIN optin can be used. The the ITL4 ITL5 tolerance optins can be used. But the tolerance should be considered carefully.
11.关于各种修正参数如漏感等的设置，是否对预防针结果具有决定作用？
Change the parameter of the simulation can predict the result and avoid the problems when using the compund has a difference torlance. e.g transformer. MOSFET ..etc
12.ocp功能如何实现？漏感存在以及耦合不紧密都会造成ocp无法实现
Normally when ocp happen the voltage on the winding drops then it cannot maintain above the UVLO then the current protection works.
Yes i agree with you in some extent. When the transformer is not coupled well due to the leakage spike the aux. winding voltage will keep very high. Simply you filter the leakage spike. then when the secondary voltage drops the aux. winding will not affected by the leakage and the voltage follows to drop below the UVLO the OCP will work.
13.在仿真收敛问题上，据说Saber比PSPICE要强，能否做个比较？
Saber is used for system level simulation. It is easier to converge the simulation for behaviour model. Pspice is design for circuit level simulation. It is used for simulating the circuit. The accurate circuit simulation should use the PSPICE is more suitable.
14.能否利用网络分析仪来绘制伯特图？具体如何做？
Yes definitely. There are testing source and testing probe on the network analyser. Normally we will break the loop and then connect a 50ohm resistor in between then injecting a sweeping frequency signal into the loop. THen connect the testing probe on the other end.
15.pspice 对于仿真不同负载，与应用到实际中之间的差异存在一定的出入，请问如何减小两者之间的差异？
Decrease the difference about the real circuit and simulation result. The main problems is setting the parameter is not same as the real system.
If you want to simulation the transformer you must know the primary inductor value and secondary inductor and using the K factor connect the two wire. you can change the coupling factor K .e.g 0.99 for simulation it. Detail you can see the presentation files page 12.
2. 开关电源的最优化的仿真主要有那些内容
It is include the average simulation and switched simulation Average simulation is used to measure the phase and gain margin and the switched simulation is using to simulated the detail switch waveform.
3. PSPICE与Saber比较，您感觉谁更适合电源仿真？
PSpice is a general purpose simulator and the Saber is a system level simulator only. PSpice can help you to investigate the circuit performance down to details.
4.能否解释一下为什么平均模型不能分析电流环的原因，谢谢
This is related to the internal structure of model. Dr. Ridley has provided an average model that work for both voltage and current loop. However this is a AC small signal model that cannot calculate bias point and predict transient performance.
5. 在采用开关模型仿真的时候经常会遇到不收敛的情况，请问吴先生怎样才能很好的解决这个问题？
The convergence problems usually happen in SMPS simulations. There are several methods for solving this problem. The transient simulation time step can increase. The large number of simulation steps in each time step can avoid in some difficult point.
The GMIN optin in the option can be used for DC bias point to solve the convergence problem.
Some other option (i.e. ITL4=1000) will affect the tolerance of the simulation. This should be carefully considered in your design.
6. Pspice能否对电源的保护功能如过流过压过热保护等进行仿真模拟？效果如何？
Pspice simulation can also include the over current proctection over voltage protection. These functions is similar to soft-start functions and other functions of the controller and SMPS. But the thermal effect usually does not be contained in the this level simulation. Except this thermal effect. Other protection functions can be simulated effectively.
7. 开关电源中最难设计、又最难调试的是高频变压器 Pspice在这方面能发挥多大作用？这套软件是否只能对安森美器件有用?软件哪里有提供？
Yes you are right. If there is no pspice circuit to help you doing simulation. You will waste a lot of time to build a breadboard for testing. PSpice is a kind of circuit simulation that you can use computer to simulate your circuit. And it nevers blows out your circuit whether you put any component value on it.
For designing the high switching frequency converter. You can refer to page 12 of the slide. First you add a ideal transformer on it. And then choose the primary magnetizing inductance of the transformer with its" leakage. Then combine with the pwm model and other components. Then you can simulate your circuit. After finished the simulation you can click on the probe icon to add some probe on the node to see the voltage current. By looking the waveform. so you can modify the components value to make your design as your expection.
Pspice is not the only software for Onsemi Parts. You can click on the link http://www.cadencepcb.com/products/pspice/
and choose the student evaluation. This is free version. Of course there are limitation of this version. Also you can buy a full version of PSpice.
8.你好，请问如何缩短模拟时间和在运算过程成不收敛的情况一般有那些？谢谢
The simulation time can be shorten by many methods. If the model is a switching model the soft-start can be omitted. So the simulation time can be shorten for simulating the steady state. The averaging model is developed for shorten the simulation. The convergence problems also can be solve setting ITL4 ITL5 and etc option.
9.我在做Pspice时，经常出现无法继续，WHY?
It is because the input parpameter is not correct. you can try to set some init condition e.g in capactor and inductor value for improve the converage problem.
10.在采用开关模型进行仿真的时候，经常会遇到不收敛的情况，请问怎样才能很好的解决这个问题？
The convergence problem is a great problem. The convergence of transient simulations can be solved by increasing the time step of the simulation. In the bias point simulation GMIN optin can be used. The the ITL4 ITL5 tolerance optins can be used. But the tolerance should be considered carefully.
11.关于各种修正参数如漏感等的设置，是否对预防针结果具有决定作用？
Change the parameter of the simulation can predict the result and avoid the problems when using the compund has a difference torlance. e.g transformer. MOSFET ..etc
12.ocp功能如何实现？漏感存在以及耦合不紧密都会造成ocp无法实现
Normally when ocp happen the voltage on the winding drops then it cannot maintain above the UVLO then the current protection works.
Yes i agree with you in some extent. When the transformer is not coupled well due to the leakage spike the aux. winding voltage will keep very high. Simply you filter the leakage spike. then when the secondary voltage drops the aux. winding will not affected by the leakage and the voltage follows to drop below the UVLO the OCP will work.
13.在仿真收敛问题上，据说Saber比PSPICE要强，能否做个比较？
Saber is used for system level simulation. It is easier to converge the simulation for behaviour model. Pspice is design for circuit level simulation. It is used for simulating the circuit. The accurate circuit simulation should use the PSPICE is more suitable.
14.能否利用网络分析仪来绘制伯特图？具体如何做？
Yes definitely. There are testing source and testing probe on the network analyser. Normally we will break the loop and then connect a 50ohm resistor in between then injecting a sweeping frequency signal into the loop. THen connect the testing probe on the other end.
15.pspice 对于仿真不同负载，与应用到实际中之间的差异存在一定的出入，请问如何减小两者之间的差异？
Decrease the difference about the real circuit and simulation result. The main problems is setting the parameter is not same as the real system.
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