Electrical angle of etpu Resolver output wrong

[Harry0001]

Hello,my etpu resolver alway output the electrial angle equal to the mechanical rotor angle,seem to be lack of  a pair poles.I want to know where can be setting in the etpu can fix this trouble?

I posted a picture to show this problem,the blue line is the EI angle from etpu and the green is the open loop EI angle,my pole-pairs is 4.Thanks!

[petervlna]

Hello,

I was talking with eTPU expert and she pointed out following:

You should use the bold highlighted function routine for conversion of electrical position to mechanical from eTPU.

    /* Get the extrapolated values from Resolver  */
    // fs_etpu_resolver_get_outputs_extrapolated(&resolver_instance, &resolver_outputs_extrapolated); zmena

     while ( fs_etpu_resolver_get_outputs_extrapolated(&resolver_instance, &resolver_outputs_extrapolated));
fs_etpu_resolver_trans_outputs_el_to_mech(RES_POLE_PAIRS,&resolver_outputs_extrapolated,&resolver_outputs_mechanical);

Best regards,

Peter

[Harry0001]

Thanks for your reply!

I has to point out that the problem is the electrical rotor angel is wrong but not the mechnical angle,i get the electrical angle form the function:

fs_etpu_resolver_get_outputs_extrapolated(&resolver_instance,
&resolver_outputs_extrapolated);

then i process the avove function output like this:

T_S32 temp_pos24;
temp_pos24 = (T_S32)resolver_outputs_extrapolated.angle;
// temp_pos24 = (T_S32)resolver_outputs_calculated.angle;
if(temp_pos24 < 0)
{
temp_pos24 = 0xFFFFFF+temp_pos24; // +2pi
}

temp_pos24 = (temp_pos24>>12)&0x0FFF; // takes only the 12 bit result

*Pos= (T_S16)(temp_pos24);

the pos div 4096,then mutl 2π，then substract π，then it bccame what has been showed in the picture i posted.

The problem is why the output of etpu "resolver_outputs_calculated.angle"is not the electrical but in fact the mechanical angle,seems to lack of the pairs poles.if I take it to divide pairs poles to get the mechanical angle,the mechanical angle will be not fit with the true condition.Thus i want to know where is wrong and where can i set the pair poles in the etpu moudle.Thanks!

[Yongbing_Nan · Accepted solution]

Hi,

The angle got from fs_etpu_resolver_get_outputs_calculated() is mechanical angle. If resolver is 1xpole pairs, motor is 4x pole pairs, electrical andgel = mechanical*4, here saturation has to be taken into account, regarding the details implement method, you can refer AN12017sw and add bold code.

ptr->Resolver_SW.fltThRotMec = ((tFloat)resolver_outputs_calculated.angle / 0x800000) * FLOAT_PI;

ptr->Resolver_SW.wRotMec.raw = (((tFloat) resolver_outputs_calculated.speed) / 0x800000) * FLOAT_PI *20000; /* rad/s */

// Mechanical rotor position - convert from FLOAT to FIX, <-1,1> range f32ThRotMe = MLIB_ConvertPU_F32FLT(MLIB_Div(ptr->fltThRotMec,FLOAT_PI));

// Electrical rotor offset position - convert from FLOAT to FIX, <-1,1> range f32ThRotElOffset = MLIB_ConvertPU_F32FLT(MLIB_Div(ptr->fltThRotElOffset,FLOAT_PI));

// Electrical rotor position calculation respecting the resolver position offset - fix point arithmetic f32ThRotEl = MLIB_ShL_F32(MLIB_MulSat_F32(f32ThRotMe,ptr->s32motorPPscale),ptr->s16motorPPscaleShift); f32ThRotEl = MLIB_Sub_F32(f32ThRotEl,f32ThRotElOffset);

// Electrical rotor position -> convert from FIX to FlOAT, <-pi, pi> range ptr->fltThRotEl = MLIB_Mul(MLIB_ConvertPU_FLTF32(f32ThRotEl), FLOAT_PI);

[Harry0001]

Thanks！the code you provided help me a lot,the problem has been solved perfectly!

[petervlna]

Hello,

Could you specify which device and which eTPU library you are referring to?

Best regards,

Peter

[Harry0001]

MPC5777C,and the etpu lib is from others,i do not know its source.

[Harry0001]

I get the blue line from the function: angle fs_etpu_resolver_get_outputs_calculated(),its angel output should be the rotor electrical angle.