Power Estimation in Piccolo F28027 HVKit

take a look at this thread
e2e.ti.com/.../1693712

hi Chris,

i read the above  link, it really helped, thank you.

but the question is,

after computing the Motor Power Consumption by the below Formula:

P_motor = (Vd * Id + Vq * Iq) * 1.5

the P_motor parameter is in per unit, how can i convert it to Watt?

is it sufficient to use the below formula or must add some other parameters?

P_motor_watt = _IQtoF(P_motor);

what about this formula in here:

// Equations for motor power
float_t motor_power_W = _IQtoF(gMotorVars.Torque_Nm) * _IQtoF(gMotorVars.Speed_krpm) * (float_t)(MATH_TWO_PI * 1000.0 / 60.0);

which formula is correct?

"the P_motor parameter is in per unit, how can i convert it to Watt?"
I would first convert the currents and voltages from per unit to Amps and Volts like we show you in the rest of the code.

ex:
gMotorVars.VdcBus_kV = _IQmpy(gAdcData.dcBus,_IQ(USER_IQ_FULL_SCALE_VOLTAGE_V/1000.0));

then do the calculation

you mean that i must write this codes?

_IQmpy(gMotorVars.Id,_IQ(USER_IQ_FULL_SCALE_CURRENT_A));

_IQmpy(gMotorVars.Iq,_IQ(USER_IQ_FULL_SCALE_CURRENT_A));

_IQmpy(gMotorVars.Vd,_IQ(USER_IQ_FULL_SCALE_VOLTAGE_V / 1000.0));

_IQmpy(gMotorVars.Vq,_IQ(USER_IQ_FULL_SCALE_VOLTAGE_V / 1000.0));

what about this formula in here:

// Equations for motor power
float_t motor_power_W = _IQtoF(gMotorVars.Torque_Nm) * _IQtoF(gMotorVars.Speed_krpm) * (float_t)(MATH_TWO_PI * 1000.0 / 60.0);

is it correct?

Generally, Motor Output Power(Kw)=Torque(N.m)*Speed(rpm)/9.5493, the 9.5493=60/(2*PI), so your equation is correct.

Below 2 lines can't get real Vd and Vq, both two are related to Vdcbus, you need to multiply the dc bus voltage to get real Vd and Vq with volt unit.
_IQmpy(gMotorVars.Vd,_IQ(USER_IQ_FULL_SCALE_VOLTAGE_V / 1000.0));
_IQmpy(gMotorVars.Vq,_IQ(USER_IQ_FULL_SCALE_VOLTAGE_V / 1000.0));

you mean that i must multiply the dc bus voltage to Vd and Vq and then convert them from per unit to Volts?

like this?
_IQmpy( _IQmpy(gMotorVars.Vd, gAdcData.dcBus) ,_IQ(USER_IQ_FULL_SCALE_VOLTAGE_V / 1000.0));
_IQmpy( _IQmpy(gMotorVars.Vq, gAdcData.dcBus) ,_IQ(USER_IQ_FULL_SCALE_VOLTAGE_V / 1000.0));

Need to multiply SQRT(2)/2 for bipolar modulation, means _IQmpy( _IQmpy(gMotorVars.Vd, gAdcData.dcBus) ,_IQ(USER_IQ_FULL_SCALE_VOLTAGE_V *0.7071/ 1000.0));

thank you but i am confused.
where did the "SQRT(2)/2" come from?

what about Id and Iq?
is there any special parameter to convert Id, Iq to Amps or just use the below formula?

_IQmpy(gMotorVars.Id,_IQ(USER_IQ_FULL_SCALE_CURRENT_A));
_IQmpy(gMotorVars.Iq,_IQ(USER_IQ_FULL_SCALE_CURRENT_A));

The caculate of Id and Iq is right.
The Vd&Vq is the output of PID regulator which is the percent of Vdc. Gereral, 0% is the Vdc/2, and Vd^2+Vq^2=1, so need to multiply SQRT(2)/2.

thank you Yanming for quick reply.

but i am very confused.

i write and test the codes, you mentioned.

look like the pic below:

but the answers don't make a sense.

if the above formula is right why my answers is not right?

i must say that i use the F28027-Launchpad supplying from 24v power supply. the output current of power supply is around 80 mA so the consumption is around 1.920W(24V x 80mA = 1920 mW).

but the Adc_Value.Power_Consumed in the above formula is around the 0.0005 and i don't know what is the unit(watt or per unit?).

what can i do?

am i right or something is wrong?

thank you again Yanming for quick reply.

i wrote the above code and the results are better now.

but i still have a problem with this part:

"You can refer to below equation to caculate the motor output power. Need to multipy _IQ(0.7071) if using SPWM mode, and you need to multiply _IQ(0.866025) if suing SVPWM mode. Generally, use the Te*n/9.5488 to caculate the motor output power."

and this part:

"

  // read Vd and Vq vectors in kV
  gMotorVars.VsFactor = _IQmpy(gMotorVars.VdcBus_kV, _IQ(0.866025));
  gMotorVars.PsFactor = _IQmpy(gMotorVars.Speed_krpm, _IQ(1.0/9.5488));

 "

i know the gMotorVars.VdcBus_kV is right and about 0.024 kV and multiply the _IQ(0.866025) make it incorrect(about 0.021).

sorry for elementary questions.  why using the _IQ(0.7071) or _IQ(0.866025) or Te*n/9.5488?

how can i recognize to choose every one of them?

and finally this part:

"gMotorVars.Ps_kW = _IQabs(_IQmpy(gMotorVars.Vd_kV, gMotorVars.Id_A)) + _IQabs(_IQmpy(gMotorVars.Vq_kV, gMotorVars.Iq_A));"

is there a "  *_IQ(1.5) " part at the end?

which one is exact? Pout_kW or Ps_kW?

thank you

1. InstaSPIN-FOC use SVPWM, so you can multiply _IQ(0.866).
2. Not multiply _IQ(1.5).

is there any document that can help me to understand _IQ(0.866)?

which one is exact? Pout_kW or Ps_kW?

thank you for complete answer.
i used the above formula and my problem solved.
the answers are seems to be write.
thanks.