How to use SV PWM in vissim/ecd?
Altair Employee Submitted by thbt86 on Thu, 11/19/2009 - 19:36
hi everybody. i'm using vissim/ecd to control V/F motor ACI( just beginner). my diagram must use SV PWM and i used space vector PWM (Quadrature) RUN ON 2407. how can i simulate and create signal on DSP. Can someone who used space vector PWM (Quadrature) block can explain me the input and output to this block? thanks
Answers
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Submitted by Anders89 on Thu, 11/19/2009 - 22:41.
You can download and watch the instructional videos that show how to compile and download to a TI target here. I recommend you start with the ECD introduction I have attached 2 files below that show V/F ACI control. One is pure simulation and is used to generate code to produce an .out file that will perform the V/F control on the LF2407. The other will run the .out file and use the PWM commands to run a virtual motor simulated in the VisSim diagram.
You can see and download the files if you are signed in.
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Submitted by thbt86 on Sat, 11/21/2009 - 09:05.
thank you very much for reply to me. i downloaded attach file but i don't understand something about it. why must gain 65 the output rotor angular, gain 25 in svggain. if i complie and load to DSP, it can generate signal PWM on DSP? or must i add fullcomparePWM block to control modune PWM on dsp kit. i'd finish a diagram use SVPWM control v/f ACI. can you give me some advise about it.
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Submitted by Anders89 on Sat, 11/21/2009 - 10:48.
The SVgain is the voltage supplied to the simulated motor, to be honest, I'm not sure what the '65' gain on the rotor speed is for. '9.55' would make more sense to convert from rad/sec to RPM. It is not so important as the speed control will generate inverter waveforms to match the speed no matter the gain.
Regarding your diagram for motor control, you have used the wrong blocks for embedded use. You used simulation only blocks. If you select menu item View > Data Types, connector pins will be colored according to their data type. Floating point pins will be red, scaled integer yellow, and pure integer green. It is important that you see only yellow and green pins in the diagram portion that will be compiled to run on the target. Yes, you can put a fullCompare PWM inside the 'PI + VHz + SVGEN - MF' block to control a real inverter attached to an AC induction motor. The attached files show how. acim_vf_openloop.vsm is the source diagram to be compiled, then *acim_vf_openloop-d.vsm' will run the diagram letting you vary the open loop frequency command with a slider.0 -
Submitted by thbt86 on Sat, 11/21/2009 - 12:58.
thank for fast reply. i downloaded this file and work with it. i don't understand the output waveform space vector PWM block is sin but it only positive( >0). if it is a 3 phase sin waveform, i think it has symmetrical. if it is PWM signal, it only has 2 level (0 and 1). why do you use block scale before input fullcomparePWM. if i don't use scale and wire direct to fullcomparePWM block. it's right or wrong. which problem will happen?
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Submitted by Anders89 on Sat, 11/21/2009 - 20:37.
The PWM block takes a fractional value between 0 and 1 on each of the 3 input pins. The input will control the duty cycle of the PWM. Yes, the hardware output of the PWM has only 2 levels, 0 (off) and 1 (on), but power is modulated by controlling the amount of on-time. The space vector wave form block produces values between +1 and -1. The PWM block needs values between 0 and 1, so the scaling maps the +1/-1 to 0/1. Without the mapping you will get wrong PWM response and a bad smell from the inverter as random signals are sent to it.
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Submitted by thbt86 on Sun, 11/22/2009 - 08:27.
sorry.i has a dsp 2407, a igbt driver in this pictur, a 3 phase ac motor 380volt/50hz. cab i use a diagram you give me to control v/f it? how i conect my dsp with digram? because i borrow DSP in my university, my teacher sure that my diagram is true. and i know run vissim om dsp. Thanks very much again.
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Submitted by Anders89 on Sun, 11/22/2009 - 22:39.
The acim_vf_openloop.vsm files below will correctly perform open-loop V/F control of a 3 phase AC induction motor. Your .bmp above does not give enough information to say if it is correct for your inverter topology. You must properly connect the LF2407 PWM pins to your IGBT drivers in the correct way. However, I updated theacim_vf_openloop.vsm files below to include an enable pin. This means that the PWM outputs will be in a high impedance state until you click the enable button. This lets you download and start the LF2407 with PWM in high impedance state. Then you can turn on the PWMs to test the the inverter and switch them off quickly if it starts to smell bad or catches fire.
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Submitted by thbt86 on Thu, 12/03/2009 - 10:42.
sorry again, but when i use V/Hz Profile Generator i don't know how much frequency in the input. the diagram acim_vf_openloop.vsm you send me don't work at 50hz. so i replace some block and it's not work. i'm doing a diagram to simulation and load to DSP for control a v/f motor ( 3 phase 380v/50hz) with herts change from 20hz~60hz. the diagram i make below but not run, i don't known why? can everyone help me. how can i see 6 sector of SV PWM if i use this diagram? the diagram space vector[PWM (Space Vector).vsm] can use code generation for dsp? thanks very much to everyone.
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Submitted by Anders89 on Fri, 12/04/2009 - 06:18.
thbt86, Your diagram has several problems.
- You can't reference actual frequency or voltage in the Volt/Hertz Profile block. You must use a fraction of full scale frequency and voltage. So if your max voltage at 100% duty cycle is 380V, and you want to start at 220V at the low frequency point, you use 220/380 = .579 at V at Low Freq Point. If your high frequency is 50Hz, and low freq is 20 Hz, your low freq point is 20/50 or 0.4 . Slope is (VhighPU-VlowPU)/(fHighPU-fLowPU). I have attached an updated diagram with proper settings and calculation of Per Unit values. (You may need the latest VisSim/ECD to get the proper slope scaling)
- You switched from Full Compare PWM to the 'Space Vector' PWM. You did not connect the period scaling pin, so the period is set to zero. Also, you can't set the deadband with the 'Space Vector' PWM, and you have an IGBT, which requires deadband setting. For that reason I recommend using the Full Compare.
You can download the updated V/Hz 50Hz diagrams below.
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Submitted by thbt86 on Tue, 12/22/2009 - 06:43.
sorry, in diagram 'acim_vf_openloop50Hz.vsm' when i pull slider to change the value frequency over 0.6 vissim has a fautl 'fixed point overflow'? i'm using VisSimEcdWeb70. How can i fix this problem? and i have a question about Space Vector Generator(Magnitude, Frequency)block, what is the frequence scaling? if i put 1 in these what's this mean? thank you and i hope for fast reply.
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Submitted by Anders89 on Thu, 12/24/2009 - 10:28.
It is fixed in the most recent download. Now the slope is calculated automatically. There is no need to enter it. Download the latest ECD here.
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Submitted by thbt86 on Fri, 12/04/2009 - 07:42.
yes, thank you! i'm using vissim v7.0 and i think it's a latest vesion. in your diagram, you can explain the offset and frequence scaling in block space vector generator, why do you enter o and 0,12. with Space Vector' PWM if i enter a carrier frequency in fourth pin, how diffirent between it and full compare? because with Space Vector' PWM i can choice EVM A or B on DSP, so i try to use it.
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Submitted by Anders89 on Fri, 12/04/2009 - 09:37.
The update was just this week. Just install the update over your current install. It will only update changed files. Do not uninstall.
The full compare PWM lets you select Timer 1 (EVA) or Timer 3 (EVB), plus you can set deadband for IGBT driving, and it generates more efficient in-line code. The 4th pin of space vector PWM takes a value between 0 and .9997 that controls the fraction of full PWM switching frequency that is desired. This is explained in the help document that you get if you click the help button. The FullCompare PWM requires scaling of the -1/+1 range from the 'Space Vector Generator (Mag Freq)' block to 0/+1. The 'Space Vector' PWM does not require such scaling.0 -
Submitted by thbt86 on Sat, 12/05/2009 - 14:30.
thank you for reply to me. i wished success and thanks again.
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