Free Energy | searching for free energy and discussing free energy

Conrad,

I do not think the PWM devices work in the manner that you described. The H-Bridge transistors are switching transistors, that is, they turn on and off, only. There is not intermediate steps. The chopping wave that you see is the average value of the PWM pulses. The losses (heat up) would be too large, if the transistors had worked as linear amplifier or with intermediate steps.

Bajac

@Bajac:

I admit doing a bad job explaining multi stepping of a stepper motor and its relationship to the Fiquera transformer.

I also admit that I do not manage to explain why one needs two DACs to drive the DRV8834 in the manner I think it should be driven.

Yes, it looks a bit strange that the two DACs give two voltage wave forms to the DRV8834 which is chopping the two full transistor bridges according to this voltage wave forms (in case you looked at my schematics). But the DRV8834 wants it like this, what can I do. The designers of the DRV8834 thought that a voltage wave form is a very good way of defining a very fine grade current change (and the current change is of course then created by the DRV8834 by chopping). And exactly this gives the very high flexibility of creating any phase shift and any "current change form" one desires.

And I never said that the full bridges in any stepper motor IC are driven in a linear or amplifying manner (all stepper motor ICs which can do MICRO stepping are chopping, switching the bridges on and off very rapidly according to a certain pulse train).

But it does not matter what I say and what I think, please read the data sheets of the stepper motor driver ICs I discussed  (DRV8834 which is very good and LMD18245 which is less suitable) and study the paper about micro stepping I cited ( http://www.stepperworld.com/Tutorials/pgMicrostepping.htm ), it says it much better than me. You will see by yourself what these ICs do and what follows from that.

If you think that the DRV8834 stepper motor driver IC is not necessary, it is fine with me. I have no stake in Texas Instruments and everybody has a different idea about how to do an experiment. I am also not selling my schematics, it is given for free as an example of a very low cost implementation which according to my unimportant opinion will do a very good job when testing the Fiquera transformer. And the ICs I propose can really be bought, they are commonplace (e.g. from Farnelle and from Arduino sellers, and I am not a salesman of Farnell, I just want to hand out useful information).

From the questions which are asked (again and again) and from the stepper motor ICs and boards cited by other people I believe to see a lack of knowledge in the field of stepper motor drivers. This is the reason why I am a bit sarcastic. One should not ask me, the only way to understanding is studying stepper motor ICs and boards and specially the art of MICRO stepping (which happens from step N to step N+1, so, each hard ware defined step of a stepper motor is subdivided into many MICRO steps mainly to make it run smoother and with less torque variations). And only what is happening in between the natural hardware steps of a stepper motor (the MICRO steps) is somehow related to driving the Fiquera transformer.

So, any stepper motor driver IC or board which can just step a stepper motor is useless, the IC or board must be able to MICRO step (at least 8 MICRO steps in order to beat the "commutator + 7 resistors" of Fiquera). In addition, most stepper motor ICs and boards stick to a 90° phase shift (of the two coil groups in a two pahse stepper motor) when MICRO stepping, which according to my humble opinion is a severe drawback when testing the Fiquera transformer (but it might not bother other experimenters).

Please publish your test circuit, I probably will write my opinion about it in this forum (as I wrote my opinion about the other stepper motor ICs and boards cited by other people).

I know that trying to teach is a bad idea, people do not want to learn, they want to build want they think is best. And many think they can beat well known facts or cut corners when doing electronics.

Finally, I do not claim that I understand the Fiquera transformer and that I can make it work better than anyone else. But I think it is a fun experiment which tickles my brain and makes me do some interesting programming. The schematics I published are also a very good circuit for testing various motor ideas which I carry around in my brain for a long time and never experimented with.

Greetings, Conrad

See attached photo for my construction of the Figuera's generator. The C-electromagnets can be adjusted to change the air gap separation distance. This one shows the driving transistors, but I will replace them as soon as I receive the stepper motor driver.


Thanks.
Bajac

Once the secondary 'Vsy' voltage is induced, the main limiting factor for the power output should be the size of the secondary wire. That is why I am using a #14AWG wire.

I am forecasting that the model of this transformer differs from the standard ones in that the primary parameters such as resistance and reactance do not affect the output power.

Wonju

KEhYo,

 The original waveform shown in the first graph is about right when you have a pure resistive load. The inductance of the primary coils should distort the shape a bit.
 
I have no comments for the second graph.
 
The third graph is not correct. You are showing two sinusoidal voltages in 90 degrees out of phase. If you applied these two signals to full wave rectifier, then, you get the correct voltage that should be applied to the primary coils. The voltage applied to the primary coils should be half-cycle sine waves. Refer to figure 21 of the document.
 
Wonju.
 

Basically in this configuration, there are two primaries on the sides and a secondary in the middle. Primaries create magnetic flux unidirectionally and the flux from each side corresponds to the induction of current in the secondary output coil in one direction only. Splitting the cycle in two halves allows the mirror "C" core part to become alternate path for the CEMF flux from the output to take a route through that core (which is not magnetized at the moment of maximum saturation with flux from the other primary). Now, I Get IT! Think about the BiTT - The same principles apply!

@Laurent (Woopy):

Your video is very interesting, thank you for showing your tests in such a clear and understandable way.

From the drawing of Fiquera (the one with the many coils) I got the idea, that one should try a very simple design as depicted in the attached drawing. I do not see any indication that one should use a rectangular transformer core and the secondary on a transversal in the middle.

------------------

I had some troubles with the TI LaunchPad and the 20 pin MSP430G2254 microprocessor. The LaunchPad can not program this rather new Microprocessor and an attempt to update the LaunchPad firmware resulted in the destruction of the two LauchPads I had. I need the 20 pin Microprocessor MSP430G2254 (or some other 20 pin Version) in order to have enough I/O lines to control the stepper motor driver IC. And the LaunchPad can not program the 20 pin Microprocessors MSP430G... without a firmware update, which is difficult to do and not really supported by TI. Well my loss was less than 20.-- Euro, but still, very annoying.

I am now fed up with the LaunchPad and switched to the Arduino Due, but it will take some time till I get one, at the moment only a few can be delivered (at least in Austria and Germany). It seemed appropriate to wait for the new Arduino Due since it came out just about now. I would have soon regretted having bought an older Arduino

The Arduino Due has two DACs (digital to analogue converters), which will make it simple to control all aspects of DRV8834 stepper motor driver IC (I got already 4 ICs, so that I can fry a few till I get it right).

So, it will take some time till I can start real tests. But once I am up with my rather ambitious hardware I should be able to try out any conceivable current curve on two coils (with a resolution of up to 256 steps). But only with 10 Volt (-10 V to + 10 Volt = 20 Volt peak to peak) and 1.5 Ampere.

Greetings, Conrad

Alrightythen...

I have found a simple way to do the coil driving with Arduino!

All you need is:
1. ONE 10k/100k Ohm potentiometer. Connect the middle leg to Arduino's "A0" analog input. The other two legs of the pot goes to +5V and GND on Arduino.
2. TWO Logic Level MOSFET transistors to do the switching (Logic level - like in IRL series -  means that a mosfet is in a conduction saturation state at just +5V put to its gate). Connect the Gate of one mosfet to "Pin 3" and the others' gate to "Pin 11". Sources go to the "GND" of the Arduino board.
3. Connect +(positive) from a battery to both "North" & "South" coils and their ends to both drains in the two mosfets and -(negative) to the Arduino's "GND" close to the Source legs of mosfets.
4. Connect fast shottky diodes across each coil to do the freewheeling of current.

Program description:
Arduino is generating a digital signal at 32 kHz frequency using 2 PWM outputs. The value for each "sample" is taken from the sine table. There are 256 values of resolution for the "shape" of the sine wave and 256 values of amplitude. You can change phase shift by changing "offset" variable. Potentiometer allows to set the analog frequency from 0 to 1023 Hz at 1 Hz resolution...


NOW copy the code below to Arduino IDE window and save it to the microconroller and HERE YOU GO!

/* CLEMENTE FIGUERAS GENERADOR DRIVER
 * modification by kEhYo77
 *
 * Thanks must be given to Martin Nawrath for the developement of the original code to generate a sine wave using PWM and a LPF.
 * http://interface.khm.de/index.php/lab/experiments/arduino-dds-sinewave-generator/
*/


#include "avr/pgmspace.h" //Store data in flash (program) memory instead of SRAM


// Look Up table of a single sine period divied up into 256 values. Refer to PWM to sine.xls on how the values was calculated
PROGMEM  prog_uchar sine256[]  = {
  127,130,133,136,139,143,146,149,152,155,158,161,164,167,170,173,176,178,181,184,187,190,192,195,198,200,203,205,208,210,212,215,217,219,221,223,225,227,229,231,233,234,236,238,239,240,
  242,243,244,245,247,248,249,249,250,251,252,252,253,253,253,254,254,254,254,254,254,254,253,253,253,252,252,251,250,249,249,248,247,245,244,243,242,240,239,238,236,234,233,231,229,227,225,223,
  221,219,217,215,212,210,208,205,203,200,198,195,192,190,187,184,181,178,176,173,170,167,164,161,158,155,152,149,146,143,139,136,133,130,127,124,121,118,115,111,108,105,102,99,96,93,90,87,84,81,78,
  76,73,70,67,64,62,59,56,54,51,49,46,44,42,39,37,35,33,31,29,27,25,23,21,20,18,16,15,14,12,11,10,9,7,6,5,5,4,3,2,2,1,1,1,0,0,0,0,0,0,0,1,1,1,2,2,3,4,5,5,6,7,9,10,11,12,14,15,16,18,20,21,23,25,27,29,31,
  33,35,37,39,42,44,46,49,51,54,56,59,62,64,67,70,73,76,78,81,84,87,90,93,96,99,102,105,108,111,115,118,121,124


};
#define cbi(sfr, bit) (_SFR_BYTE(sfr) &= ~_BV(bit)) //define a bit to have the properties of a clear bit operator
#define sbi(sfr, bit) (_SFR_BYTE(sfr) |= _BV(bit))//define a bit to have the properties of a set bit operator


int PWM1 = 11; //PWM1 output, phase 1
int PWM2 = 3; //PWM2 ouput, phase 2
int offset = 127; //offset is 180 degrees out of phase with the other phase


double dfreq;
const double refclk=31376.6;      // measured output frequency
int apin0 = 10;


// variables used inside interrupt service declared as voilatile
volatile byte current_count;              // Keep track of where the current count is in sine 256 array
volatile unsigned long phase_accumulator;   // pahse accumulator
volatile unsigned long tword_m;  // dds tuning word m, refer to DDS_calculator (from Martin Nawrath) for explination.


void setup()
{
  pinMode(PWM1, OUTPUT);      //sets the digital pin as output
  pinMode(PWM2, OUTPUT);      //sets the digital pin as output
  Setup_timer2();
 
  //Disable Timer 1 interrupt to avoid any timing delays
  cbi (TIMSK0,TOIE0);              //disable Timer0 !!! delay() is now not available
  sbi (TIMSK2,TOIE2);              //enable Timer2 Interrupt


  dfreq=10.0;                    //initial output frequency = 1000.o Hz
  tword_m=pow(2,32)*dfreq/refclk;  //calulate DDS new tuning word
 
  // running analog pot input with high speed clock (set prescale to 16)
  bitClear(ADCSRA,ADPS0);
  bitClear(ADCSRA,ADPS1);
  bitSet(ADCSRA,ADPS2);


}
void loop()
{
        apin0=analogRead(0);             //Read voltage on analog 1 to see desired output frequency, 0V = 0Hz, 5V = 1.023kHz
        if(dfreq != apin0){
          tword_m=pow(2,32)*dfreq/refclk;  //Calulate DDS new tuning word
          dfreq=apin0;
        }
}


//Timer 2 setup
//Set prscaler to 1, PWM mode to phase correct PWM,  16000000/510 = 31372.55 Hz clock
void Setup_timer2()
{
  // Timer2 Clock Prescaler to : 1
  sbi (TCCR2B, CS20);
  cbi (TCCR2B, CS21);
  cbi (TCCR2B, CS22);


  // Timer2 PWM Mode set to Phase Correct PWM
  cbi (TCCR2A, COM2A0);  // clear Compare Match
  sbi (TCCR2A, COM2A1);
  cbi (TCCR2A, COM2B0);
  sbi (TCCR2A, COM2B1);
 
  // Mode 1  / Phase Correct PWM
  sbi (TCCR2B, WGM20); 
  cbi (TCCR2B, WGM21);
  cbi (TCCR2B, WGM22);
}




//Timer2 Interrupt Service at 31372,550 KHz = 32uSec
//This is the timebase REFCLOCK for the DDS generator
//FOUT = (M (REFCLK)) / (2 exp 32)
//Runtime : 8 microseconds
ISR(TIMER2_OVF_vect)
{
  phase_accumulator=phase_accumulator+tword_m; //Adds tuning M word to previoud phase accumulator. refer to DDS_calculator (from Martin Nawrath) for explination.
  current_count=phase_accumulator >> 24;     // use upper 8 bits of phase_accumulator as frequency information                     
 
  OCR2A = pgm_read_byte_near(sine256 + current_count); // read value fron ROM sine table and send to PWM
  OCR2B = pgm_read_byte_near(sine256 + (uint8_t)(current_count + offset)); // read value fron ROM sine table and send to PWM, 180 Degree out of phase of PWM1
}