is isolation is neccesary between arduino uno and ir2110 driver ic

i wana to make an 3 phase inverter which variable voltage and variable frequency (v/f), controling 3 phase induction motor.415v,50hz,1/4hp

spwm frequency is 32khz. driver ic -ir2110, vcc and com is connected to 15v and grnd (external voltage supply regulated by 7815 ic) vdd and vss is connected to vcc and grnd of aurdino uno board. both ground is shorted(aurdino uno boardand external supply)

nw my aurdino uno board is damaged. if i use isolated ckt , which optcoupler ic is used ?? interface ckt diag?? spwm freq is 32 khz.

also i hav doubt in design the value of bootstap capacitor used in ir2110 .it charged when low side switch is on. is 400nf or 4.7micro farad is neccesary ?? dc link voltage 500v.

below the sketch

/****************************************************************** * DDS-sinewave - 3phase * ******************************************************************/

include "avr/pgmspace.h"

include "avr/io.h"

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 sbi(sfr, bit) (_SFR_BYTE(sfr) |= _BV(bit))

define PWM_OUT_1 11 // PWM output on pin 11

define PWM_OUT_2 10 // PWM output on pin 10

define PWM_OUT_3 9 // PWM output on pin 9

define LED_PIN 13 // LED status on pin 13

define TEST_PIN 7 // Scope trigger on pin 7

define POTEN_IN 0 // Potentiometer on pin 0

define OFFSET_1 85 // Offset for second-phase

define OFFSET_2 170 // Offset for third-phase

double dfreq; const double refclk = 31376.6; // measured const uint64_t twoTo32 = pow(2, 32); // compute value at startup and use as constant

// variables used inside interrupt service declared as voilatile volatile uint8_t icnt; // var inside interrupt volatile uint8_t icnt1; // var inside interrupt volatile uint8_t c4ms; // counter incremented every 4ms volatile uint32_t phase_accum; // pahse accumulator volatile uint32_t tword_m; // dds tuning word m

void setup() { pinMode(LED_PIN, OUTPUT); // sets the digital pin as output Serial.begin(115200); // connect to the serial port Serial.println("DDS Test");

pinMode(TEST_PIN, OUTPUT); // sets the digital pin as output pinMode(PWM_OUT_1, OUTPUT); // PWM output / frequency output pinMode(PWM_OUT_2, OUTPUT); // PWM output / frequency output pinMode(PWM_OUT_3, OUTPUT); // PWM output / frequency output

// Setup the timers setup_timer1(); setup_timer2();

// disable interrupts to avoid timing distortion cbi (TIMSK0, TOIE0); // disable Timer0 !!! delay() is now not available sbi (TIMSK2, TOIE2); // enable Timer2 Interrupt dfreq = 1000.0; // initial output frequency = 1000.0 Hz tword_m = twoTo32 * dfreq / refclk; // calulate DDS new tuning word }

void loop() { if (c4ms > 250) // timer / wait for a full second { c4ms = 0; dfreq = analogRead(POTEN_IN); // read Poti on analog pin 0 to adjust output frequency from 0..1023 Hz cbi (TIMSK2, TOIE2); // disble Timer2 Interrupt tword_m = twoTo32 * dfreq / refclk; // calulate DDS new tuning word sbi (TIMSK2, TOIE2); // enable Timer2 Interrupt Serial.print(dfreq); Serial.print(" "); Serial.println(tword_m); } }

// timer1 setup // set prscaler to 1, PWM mode to phase correct PWM, 16000000/512 = 31.25kHz clock void setup_timer1(void) { // Timer1 Clock Prescaler to : 1 sbi (TCCR1B, CS10); cbi (TCCR1B, CS11); cbi (TCCR1B, CS12); // Timer0 PWM Mode set to Phase Correct PWM cbi (TCCR1A, COM1A0); // clear Compare Match sbi (TCCR1A, COM1A1); cbi (TCCR1A, COM1B0); // clear Compare Match sbi (TCCR1A, COM1B1);

sbi (TCCR1A, WGM10); // Mode 1 / Phase Correct PWM cbi (TCCR1A, WGM11); cbi (TCCR1B, WGM12); cbi (TCCR1B, WGM13); }

// timer2 setup // set prscaler to 1, PWM mode to phase correct PWM, 16000000/512 = 31.25kHz clock void setup_timer2(void) { // 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); sbi (TCCR2A, WGM20); // Mode 1 / Phase Correct PWM cbi (TCCR2A, WGM21); cbi (TCCR2B, WGM22);

}

//****************************************************************** // Timer2 Interrupt Service at 31.25kHz = 32us // this is the timebase REFCLOCK for the DDS generator // FOUT = (M (REFCLK)) / (2 exp 32) // runtime : 8 microseconds ( inclusive push and pop) ISR(TIMER2_OVF_vect) { sbi(PORTD, TEST_PIN); // Test / set PORTD,TEST_PIN high to observe timing with a oscope phase_accum += tword_m; // soft DDS, phase accu with 32 bits icnt = phase_accum >> 24; // use upper 8 bits for phase accu as frequency information OCR2A = pgm_read_byte_near(sine256 + icnt); // read value fron ROM sine table and send to PWM DAC OCR1A = pgm_read_byte_near(sine256 + (uint8_t)(icnt + OFFSET_1)); OCR1B = pgm_read_byte_near(sine256 + (uint8_t)(icnt + OFFSET_2)); if (icnt1++ == 125) // increment variable c4ms every 4 milliseconds { c4ms++; icnt1 = 0; } cbi(PORTD, TEST_PIN); // reset PORTD,TEST_PIN }

also help me to learn sketch.