PopularFX
Home Help Search Login Register
Welcome,Guest. Please login or register.
2017-12-13, 09:09:22
News: Registration with the OUR forum is now by invitation only.

Pages: 1 2 3 [4]
Author Topic: Rediscovering Zaev’s ferro-kessor  (Read 2606 times)

Full Member
***

Posts: 102
Will be manipulating the gap with some magnets, not sure how to find out if the core is half saturated.

Hi Itsu,

I described the procedure here
http://www.overunityresearch.com/index.php?topic=3453.msg65653#msg65653

Regards,
-V.


---------------------------
The only way of discovering the limits of the possible is to venture a little way past them into the impossible.
   

Full Member
***

Posts: 102
I'm sure Vasik will have more to add to this but IMO you could use the formulae found at this link-
https://www.supermagnete.de/eng/faq/How-do-you-calculate-the-magnetic-flux-density

In my experience theoretical calculations for magnetic circuits are difficult and give not satisfactory results.
There are many factors which contribute to the issue.
For example small air gap make big difference, but you can't measure it precisely.

Regards,
-V.



---------------------------
The only way of discovering the limits of the possible is to venture a little way past them into the impossible.
   
Sr. Member
****

Posts: 418
Hi Vasik and Itsu,

In my attempts to find different PM/core combos I have discovered a source of measurement error in my previous tests using my circuit as posted. 

The error lies with the slow turn off time of the P-channel mosfet M2 in the "Vasik Test Schematic".  The turn off delay between M1 and M2 is only ~130ns but when the cursors are correctly lined up on the input measurements to account for this, the overall COP<1 in all the tests I'm currently running!  This error was also responsible for the apparent gains at the higher supply voltages due to the reduced input measurement periods which amplified the error.

I have created a gapped (.010") core arrangement wherein a PM is placed between two vertical ferrite poles and this assembly is placed across the core gap.  A separate ferrite pole is placed across the top of the two vertical poles that allows tuning of the amount of PM flux reaching the core.  See pix below.  In this manner the % of coil/PM flux can be set and optimized experimentally.  With this arrangement, I still can not achieve COP>1 with the above error correction.

Regards,
Pm



   

Full Member
***

Posts: 102
Hi Vasik and Itsu,

In my attempts to find different PM/core combos I have discovered a source of measurement error in my previous tests using my circuit as posted. 

The error lies with the slow turn off time of the P-channel mosfet M2 in the "Vasik Test Schematic".  The turn off delay between M1 and M2 is only ~130ns but when the cursors are correctly lined up on the input measurements to account for this, the overall COP<1 in all the tests I'm currently running!  This error was also responsible for the apparent gains at the higher supply voltages due to the reduced input measurement periods which amplified the error.

I have created a gapped (.010") core arrangement wherein a PM is placed between two vertical ferrite poles and this assembly is placed across the core gap.  A separate ferrite pole is placed across the top of the two vertical poles that allows tuning of the amount of PM flux reaching the core.  See pix below.  In this manner the % of coil/PM flux can be set and optimized experimentally.  With this arrangement, I still can not achieve COP>1 with the above error correction.

Regards,
Pm

Hi Partzman,

It's good that you found an issue with measurements.
Have you tried measuring BH curve ? Can you see offset created by permanent magnet ?
For me such core setups never worked, I guess because magnet too "far away" and its field get too dispersed...

Regards,
-V.

Edit: I tried draw how it supposed to be, please see attached picture.
« Last Edit: 2017-12-02, 07:13:46 by Vasik041 »


---------------------------
The only way of discovering the limits of the possible is to venture a little way past them into the impossible.
   

Hero Member
*****

Posts: 1107
Hi Vasik and Itsu,

In my attempts to find different PM/core combos I have discovered a source of measurement error in my previous tests using my circuit as posted. 

The error lies with the slow turn off time of the P-channel mosfet M2 in the "Vasik Test Schematic".  The turn off delay between M1 and M2 is only ~130ns but when the cursors are correctly lined up on the input measurements to account for this, the overall COP<1 in all the tests I'm currently running!  This error was also responsible for the apparent gains at the higher supply voltages due to the reduced input measurement periods which amplified the error.

I have created a gapped (.010") core arrangement wherein a PM is placed between two vertical ferrite poles and this assembly is placed across the core gap.  A separate ferrite pole is placed across the top of the two vertical poles that allows tuning of the amount of PM flux reaching the core.  See pix below.  In this manner the % of coil/PM flux can be set and optimized experimentally.  With this arrangement, I still can not achieve COP>1 with the above error correction.

Regards,
Pm
Nice work PM. Carry on!
Timing issues plague efforts to make good power measurements in the kinds of devices that interest us. You've identified a timing issue related to the circuitry, but when I read this I also thought of timing issues related to scope probes, specifically active probes like differential voltage probes and current probes. As you know these will always have some lag time or latency in what they send to the scope, when compared to ordinary passive voltage probes. This is referred to in the literature as "probe skew". Most modern scopes will have some way, either automated or manual, to "de-skew" channel timing measurements to account for differences in latency between different types of probes connected to different channels of the scope. Probe latency usually won't be as much as 130 ns though! But it can be enough to screw up power calculations involving probes of different latencies.
Even the Rigol 1054z scopes have a manual setting to delay channels for de-skewing purposes. So if we are using an active current probe with, say, 30 ns latency in CH1 and a passive voltage probe with essentially zero latency in CH2, to get accurate power computations we would need to delay CH2 by that same 30 ns in order to synchronize the probes.
(This was one of the errors that Steorn made in their early Orbo magnetic motor testing; they failed to de-skew their active differential and current probe channels to have them properly synchronized.)



---------------------------
"The easiest person to fool is yourself" -- Richard Feynman
   
Sr. Member
****

Posts: 418
Hi Partzman,

It's good that you found an issue with measurements.
Have you tried measuring BH curve ? Can you see offset created by permanent magnet ?
For me such core setups never worked, I guess because magnet too "far away" and its field get too dispersed...

Regards,
-V.

Edit: I tried draw how it supposed to be, please see attached picture.

Hi Vasik,

I have not yet done a BH curve measurement with this arrangement but was rather using the change in inductance for determining the PM flux offset effects on the core.  With the advanced math on the scope, I can produce an integrated flux waveform that I would like to use as a source for the BH curve rather than external analog components, but I haven't found how the scope will allow this at the moment.  It seems to be fixed on channels 3 and 4 for the XY display.

Regards,
Pm
   
Sr. Member
****

Posts: 418
Nice work PM. Carry on!
Timing issues plague efforts to make good power measurements in the kinds of devices that interest us. You've identified a timing issue related to the circuitry, but when I read this I also thought of timing issues related to scope probes, specifically active probes like differential voltage probes and current probes. As you know these will always have some lag time or latency in what they send to the scope, when compared to ordinary passive voltage probes. This is referred to in the literature as "probe skew". Most modern scopes will have some way, either automated or manual, to "de-skew" channel timing measurements to account for differences in latency between different types of probes connected to different channels of the scope. Probe latency usually won't be as much as 130 ns though! But it can be enough to screw up power calculations involving probes of different latencies.
Even the Rigol 1054z scopes have a manual setting to delay channels for de-skewing purposes. So if we are using an active current probe with, say, 30 ns latency in CH1 and a passive voltage probe with essentially zero latency in CH2, to get accurate power computations we would need to delay CH2 by that same 30 ns in order to synchronize the probes.
(This was one of the errors that Steorn made in their early Orbo magnetic motor testing; they failed to de-skew their active differential and current probe channels to have them properly synchronized.)

Hi TK,

Yes, I have been victim of probe de-skew many times in the past as you well know.  In my case, it has been the current probes that are the biggest offender.  They can only be trusted with high frequencies or fast rise and fall time waveforms if checked against a good non-inductive CSR at the frequency of interest.

Tek has automatic de-skewing of probes it recognizes but the fact is, each probe is slightly different and each channel can also be slightly different from the rest, so to really get down to optimum accuracy, it's up to the operator to be sure all are synchronized as you point out.

Regards,
Pm 
   
Hero Member
*****

Posts: 1825


Buy me some coffee
Hi TK,

Yes, I have been victim of probe de-skew many times in the past as you well know.  In my case, it has been the current probes that are the biggest offender.  They can only be trusted with high frequencies or fast rise and fall time waveforms if checked against a good non-inductive CSR at the frequency of interest.

Tek has automatic de-skewing of probes it recognizes but the fact is, each probe is slightly different and each channel can also be slightly different from the rest, so to really get down to optimum accuracy, it's up to the operator to be sure all are synchronized as you point out.

Regards,
Pm

Could you not just place all your scope probes on the same point of the DUT-say like the CVR,and make sure all of the scopes waveforms from each channel  are in phase ?


Brad
   

Hero Member
*****

Posts: 1107
Could you not just place all your scope probes on the same point of the DUT-say like the CVR,and make sure all of the scopes waveforms from each channel  are in phase ?


Brad

Usually, yes. In any case a reading from a current probe should be checked against a reading from a CVR if possible, for timing, frequency response, amplitude of response and even _direction_ of response, as it is easy to get the probe the wrong way round on the conductor and not realize it.


---------------------------
"The easiest person to fool is yourself" -- Richard Feynman
   
Sr. Member
****

Posts: 418
Could you not just place all your scope probes on the same point of the DUT-say like the CVR,and make sure all of the scopes waveforms from each channel  are in phase ?


Brad

Yes. 

Pm
   
Pages: 1 2 3 [4]
« previous next »


 

Home Help Search Login Register
Theme © PopularFX | Based on PFX Ideas! | Scripts from iScript4u 2017-12-13, 09:09:22