Embedded Files
Voltage Sensor
Voltage Sensor
The voltage sensor is simply two series resistors. A voltage divider scales down a voltage range to a range that can be accepted by an analog pin on the Arduino. The sensor selected can withstand a range from 0 - 25 volts.
The voltage sensor is simply two series resistors. A voltage divider scales down a voltage range to a range that can be accepted by an analog pin on the Arduino. The sensor selected can withstand a range from 0 - 25 volts.
20 Amp Current Sensor
20 Amp Current Sensor
The 20 amp current sensor was picked as a second option as the resolution on the 150 amp sensor is low for this application. Although this sensor has a much greater resolution and is plenty accurate it is not large enough. With this sensor installed, the inverter would fault every time it was turned on. After looking into it, I have concluded that the sensor restricts the amount of current that can flow to the inverter, as the connections and traces are simply too small.
The 20 amp current sensor was picked as a second option as the resolution on the 150 amp sensor is low for this application. Although this sensor has a much greater resolution and is plenty accurate it is not large enough. With this sensor installed, the inverter would fault every time it was turned on. After looking into it, I have concluded that the sensor restricts the amount of current that can flow to the inverter, as the connections and traces are simply too small.
150 Amps Current Sensor
150 Amps Current Sensor
The 150 amp current sensor was initially selected as it has heavy duty terminals and it was the same price as lower rated sensors. Upon working with the sensor, it became clear it has some major flaws for this application. With such a large range of currents it can measure and a low resolution analog to digital converter (ADC) on the Arduino this created an issue. The ADC takes values from 0 to 150 amps and converts it to a value between 0 and 1023. With a low resolution ADC the number of amps per point comes out to 0.15 which is not terrible. The value that came in from the ADC when there was no current through the sensor was 512. This marks the center point of the ADC's range. From this I concluded the sensor was actually bidirectional and therefore had a 300 amp range. This means the actual amps per point is 0.30, which is very poor. A third of an amp resolution is not terrible if you are over roughly 30 amps but for a system that will most likely never exceed that, it means every measurement has substantial error. After trying another current sensor, the 150 amp sensor was used for the final deliverable as it does not prevent the inverter from turning on.
The 150 amp current sensor was initially selected as it has heavy duty terminals and it was the same price as lower rated sensors. Upon working with the sensor, it became clear it has some major flaws for this application. With such a large range of currents it can measure and a low resolution analog to digital converter (ADC) on the Arduino this created an issue. The ADC takes values from 0 to 150 amps and converts it to a value between 0 and 1023. With a low resolution ADC the number of amps per point comes out to 0.15 which is not terrible. The value that came in from the ADC when there was no current through the sensor was 512. This marks the center point of the ADC's range. From this I concluded the sensor was actually bidirectional and therefore had a 300 amp range. This means the actual amps per point is 0.30, which is very poor. A third of an amp resolution is not terrible if you are over roughly 30 amps but for a system that will most likely never exceed that, it means every measurement has substantial error. After trying another current sensor, the 150 amp sensor was used for the final deliverable as it does not prevent the inverter from turning on.
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