ADE7763 Voltage channel attenuation network and Vrms register reading problem

[Deepak Rathore]

Good morning frnds ,


i am using ADE7763 in my project of Energy meter.i have succesfully made SPI communication between ADE7763 and MCU. and i also successfully got Completed the IRMs part.
but I have some problem in the Vrms register reading and attenuation part.

I am giving Ac Voltage in the range of 0-250VAC. and according to that i m getting mV on the V2P pin of ADE7763 which is as foollows.

VAC               Analog Input (V2P to Agnd)       Vrms Reading
3                        0.006                                 596773
20                      0.019                                  603404                           
50                      0.047                                  605090                          
80                      0.075                                  678500                          
100                    0.093                                   766505                          
150                    0.139                                   1013334                         
200                    0.186                                   1272118                     
250                    0.231                                   1526387

as per my readings and data i m getting too much high readings in the range of 0-50VAC.
and second problem is that on the same lower voltage of 3VAC, i m getting different different readings in the Vrms register that creates very big problem in my project.

so please help to troubleshoot the Vrms Part.

 

[FvM]

An DC offset superimposed to the voltage measurement input would be the most simple explanation. Check your circuit.

 

[Deepak Rathore]

thanks FvM for your reply,

but i did not get anything that u say in above post. please explain in detail so i cn understand what u want to stay.

Deepak.

 

[FvM]

I'm talking about offset voltage, review the datsheet for details. By the way, I shouldn't have answered to this cross-posted thread.

 

[Deepak Rathore]

sorry Fvm for to cross post this thread in different forum but i have to do this becaz i only wan to solve my this doubt ASAP.

i have seen in the datasheet about the DC offset and have set offset in the Vrms part. but one my major doubt is that i m getting different different values on the same voltage. so due to this my whole calibration becomes wrong.

i did not find any way to solve this problem. so i post here.

Deepak.

 

[FvM]

A coarse correction of input offset must be done for the input amplifiers first.

At first sight, the offset voltages in your measurement seem to be slightly outside specification, which can mean that you have either a defective chip or wiring fault in your circuit. I would try nevertheless to minimize the Vrms reading with shorted input by

1. adjusting CH2OS
2. adjusting VRMSOS

The offset error specification in the datasheet suggests that adjustment of CH2OS is always required for meaningful measurement results.

 

[Deepak Rathore]

A coarse correction of input offset must be done for the input amplifiers first.

At first sight, the offset voltages in your measurement seem to be slightly outside specification, which can mean that you have either a defective chip or wiring fault in your circuit. I would try nevertheless to minimize the Vrms reading with shorted input by

1. adjusting CH2OS
2. adjusting VRMSOS

The offset error specification in the datasheet suggests that adjustment of CH2OS is always required for meaningful measurement results.

thanks FvM for ur great contribution in the Vrms part.finally i got my Vrms and Irms part as per my reference meter because i made some changes in the hardware and Firmware.

can u help me to read the Active power. i m making following config in the ADE7763.

LineCYC register: 0d200(0x00C8)
Mode Regiater(0x09): 0x0080(Enabling line cycle accumulation)
mask register(0x0A): 0x0014( both for ZX and CYCEND).

and then i m reading the LAENERGY Register(0x04). but i m not getting proper readings in the Register readings.


Deepak.