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Power Factor Correction for 3 phase Generator


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#1 feelinhipp

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Posted 05 March 2003 - 05:02 AM

Hi I am a student working on PF correcting a generator for a Hybrid Truck. I am one student of 20 that is involved in the development of the vehicle. We do not have funds to purchase a new generator so we thought that the best way to improve the real power output was to control the PF. The only thing is that we have no experience in this and were wondering if you could give us some advice. The generator that I am using experiences various loads (for example, when the driver steps on the gas, slows down, turns on/off things) so I thought the best way to power factor correct is to use some type of controller. I was wonder if you new of any controllers that I could use to control the circuit. Also do you know what kind of capacitors I could use. Names or part numbers would be useful so that I can reference data sheets and order parts. I have read that controllers are needed along with caps but do not know where to find these devices. Most students are ME (Mechanical engineers) but I am an EE so I have some understanding of the problem. One of the biggest difficulties I found was finding the correct components (capacitors and controllers) so if you had references that would be great. I thought about designing for the PF correction for the generators rated conditions but I am not sure if the vehicle will experience any problems when the load changes. Any help would be GREATLY appreciated. The generator that I am using is 3 phase, 40KVA, .75 PF, 400hz. Thanks for your help.

#2 marke

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Posted 06 March 2003 - 09:08 AM

Hello feelinhipp

I wonder how you are controlling the speed of the motors? This determines the suitability of applying power factor correction to the generator.
Power factor correction is the ratio between KW and KVA and this is affected by the angle between the voltage and the current, and also the distortion of the current waveform. If you connect a standard induction motor to the output of the generator, then yes you can get benefit from the connection of power factor correction capacitors. If however, the motor is a DC motor, or an AC motor driven by an inverter, you can not correct the power factor by adding capacitors due to the power factor bing low because of harmonics present rather than inductive current.
Perhaps some more detail, and we may be able to help more.

Best regards,

#3 feelinhipp

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Posted 07 March 2003 - 05:38 PM

Hello

The 3 phase AC generator is coupled to a gas powered motor. The motor responds to the driver who is either accelerating or not. The gas power motor spins the 3 phase generator which produces AC voltage. We have the gas power motor in series with the AC generator which is in parallel with the batteries. The 3 phase AC generator output is a rectified to DC and the DC voltage is controlled by a DC to DC converter to charge the trucks batteries. I hope this helps and thanks for your help

#4 marke

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Posted 08 March 2003 - 03:11 AM

You would only apply power factor correction to the output of the generator if the generator supplied an inductive load, such as an AC Induction motor, and the generator ran at a constant frequency (speed). Otherwise, there will not be consistant benefits from the addition of power factor correction.
Best regards,




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