Help interpreting a design for power management unit

In summary, the conversation discusses a person's interest in building a PMU for domestic use and their confusion on the sampling rate and its relationship to the mains frequency. They also mention the need for oversampling and the challenges of transitioning theoretical knowledge to a real-life application. The conversation ends with the person wondering if they need to reconstruct the waveform or if they can just read the binary values from the ADC on a microcontroller.
  • #1
jendrix
122
4
Hello,

I have been looking to build a pmu similar to this device, it will be for domestic use.

https://www.digikey.com/en/articles/techzone/2014/jan/low-cost-microcontroller-based-phasor-measurement-units-improve-smart-grid-reliability

I am having a bit of trouble with the sampling part and was unsure whether it was a typo. It says "AC signals are measured 30 times per cycle and 1200 times per second"

If this is from a 60Hz supply then wouldn't it end up 1800 times per second?

There is also this part later on

"The microcontroller receives a filtered analog signal as input to the A/D. These signals are converted at a minimum sample rate of 1200 ksps"

Wouldn't 1200ksps be too high, surely that would be a sampling rate of 1.2MHz, I have seen other devices which sample in the KHz range.Regards
 
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  • #2
I agree with you. They also refer to figure 1 as showing how sampling at 1200 samples per second helps show up oscillation, yet the time axis on figure 1 is in hours.
 
  • #3
jendrix said:
Wouldn't 1200ksps be too high, surely that would be a sampling rate of 1.2MHz, I have seen other devices which sample in the KHz range.
As far as I know digital postprocessing (especially filtering) requires quite an oversampling. But 1.2MHz indeed is a bit too much. Guess somebody there strongly believes in marketing...

CWatters said:
They also refer to figure 1 as showing how sampling at 1200 samples per second helps show up oscillation, yet the time axis on figure 1 is in hours.
In the context of the graph it's OK.
 
  • #4
Thanks, so was probably a typo?

So where does the 1200 come from? Wouldn't it be 1800 samples per second?
 
  • #5
I agree, 30*60=1800, not 1200.

jendrix said:
I have been looking to build a pmu similar to this device, it will be for domestic use.

Now that's interesting. Do you have any plans? any hopes? for what to do with it when it is complete?
 
  • #6
anorlunda said:
I agree, 30*60=1800, not 1200.
Now that's interesting. Do you have any plans? any hopes? for what to do with it when it is complete?

It's actually for a fun project believe it or not, I'm finding it quite challenging as I have mainly done theory in the past, so transitioning that knowledge to a real life application should be fun.

If the aim were 30 samples per minute does that mean I would need to sample at 30x the mains frequency or would I be able to sample lower, reconstruct the wave and get the data from there? I was confused whether I would need to even reconstruct the waveform or could I merely just take the output from the ADC and read the binary values on a microcontroller? Regards
 

FAQ: Help interpreting a design for power management unit

1. What is a power management unit (PMU)?

A power management unit is an electronic device that is responsible for controlling and regulating the flow of electrical power to different components of a system. It is commonly used in electronic devices such as smartphones, laptops, and other portable devices to optimize power consumption and prolong battery life.

2. How does a PMU work?

A PMU works by monitoring the power consumption of different components in a system and adjusting the power supply accordingly. It uses various techniques such as voltage regulation, power gating, and clock gating to manage power consumption and ensure efficient use of energy.

3. What is the importance of interpreting a design for a PMU?

Interpreting a design for a PMU is crucial as it helps to identify potential issues and optimize the power management strategy for a system. It also ensures that the PMU is properly integrated and functioning correctly, which can significantly impact the performance and battery life of electronic devices.

4. What are the common challenges in interpreting a design for a PMU?

One of the main challenges in interpreting a design for a PMU is understanding the complex interactions between different components and their power requirements. Additionally, designing a PMU that can efficiently manage power for a wide range of components and varying workloads can also be a challenge.

5. How can a scientist help with interpreting a design for a PMU?

A scientist can use their expertise in electronic engineering and power management to analyze and interpret the design for a PMU. They can also use various simulation tools and techniques to test and optimize the PMU's performance, ensuring efficient power management for the system.

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