I am using STPM34 for measuring RMS voltages. When I measure grid voltages it's fine. But I read the inverter output voltage, the value is oscillating from 0 to 500v. Please help me to resolve this.

THANGAMUTHU · ‎2021-03-23

Peter BENSCH · ‎2021-03-24

What is the inverter output voltage: AC or DC?
When AC: what frequency?
How did you connect the STPM34 to this voltage?
Regards
/Peter

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THANGAMUTHU · ‎2021-03-24

Inverter Output voltage : 200 - 270V AC

Frequency : 50Hz

Javier1 · ‎2021-03-25

we need to see te code aswell, did you probed the inverter output with an oscilloscope?

Maybe is much much noisier and spikey than you expect. (specially with no load attached)

THANGAMUTHU · ‎2021-03-25

V factor = VREF * (1 + (R1 / R2)) / (AU * CALIB_V * DPOW)

= (1.18 * (1+ (810000/470))) / ( 2 * 0,875) = 116274,11

I factor = VREF / (AI * CALIB_I * DPOW * KSI * KINT )

= 1.18 / (2 * 0,875 * 0,00260 * 1) = 25934,06

By using the above formula we calculated Voltage and Current. For Grid Voltage STPM34 is reading Correctly, we are facing the issue when reading inverter output AC voltage. I have attached waveforms across the VIP1 pin. I have changed the Capacitor across VIP1 pin 10nF to 100nF but also facing the issue same.

Javier1 · ‎2021-03-25

that looks like a very noisy signal.....

What about triggering the ADC reading only when the pwm event?

THANGAMUTHU · ‎2021-03-31

Kindly Suggest proceeding further?

Grid Input
Inverter Input