AC energy monitoring and control module

[ammaree]

Can I suggest that the following design be considered.

Design:   AC Energy monitoring and control  module            

1.0    Voltage measurement
1.1    AC Voltage range   0 -> 110/240 Volts, 50/60Hz
1.2    Use small onboard transformer to step down voltage
1.3    Feed voltage from secondary to voltage measurement input (see 3.0 & 4.0 below)
1.4    Secondary LV output used to provide 1A DC supply for base module
            
2.0    Current measurement   #1         #2         #3
2.1    AC Current Range         0 -> 5A AC   0 -> 10A AC   0 -> 20A AC
2.2    Use Current Transformer (CT) for electrical isolation (solid or split core)
2.3    Make provision for at least 2 separate single phase measurements
2.4    Feed output from CTs to current measurement inputs (see 3.0 & 4.0 below)
2.5    Range selection use 2 or 3 jumpers to match CT connected to correct burden
2.6    Alternative to CTs can be Hall Effect sensors (wired series with relay contacts)

3.0 Option 1: MCU ADC energy measurement
3.1    Uses onboard MCU ADCs to measure voltage/current & calculate power & energy
3.2    Must be able to do both average & RMS values
3.3    MCU need to have sufficient processing Flash (~128Kb) & SRAM (~16/32Kb)
3.4 ADC 12Bit minimum, support 4 channels interleaved conversion, 1MS/s
3.5    Preferably ADC should be DMA driven with IRQ alerting

4.0 Option 2: Smart Meter energy measurement
4.1    Uses an existing energy measurement IC to do all measurements and calculations.
4.2    Primary requirement is for 2x/3x single phases (not 1x 3phase)
4.3    MicroChip      ATSENSE 101   ATSENSE 201      ATSENSE 301
4.4    Analog Devices   ADE7754   ADE7758      ADE7854
4.5    Linear Tech      LT2940      LT2945/6/7(??)
4.6    Silergy         78M66xx   78M6610+LMU   

5.0    Power control
5.1    Uses relays (1 for each CT) rated at 20A each
5.2    AC supply to relay contacts to be via single (fused) supply line
5.3    Optional mini busbar to link Neutral/Earth in to 3x Neutral/Earth out
            
6.0 General
6.1    Interface to base module can be SPI (preferred) or UART (1Mb/s minimum)
6.2    DC power available on 2.5mm barrel connector
6.3 End of Conversion signal to MCU IRQ via spare (UART?) pin is required
6.4 Same basic design can be used for 1 and 4 channel current sense/control models.

The key to the success of this module will lie in the software functionality for the energy measurement function. Should an MCU design be selected I would be very happy to contribute my existing code (working on CC3200 ADC with DMA) to the module and to further development to enhance.

I am sure I am not the only person with this requirement and based on the 110/240V design specifications the module could have international application. If it will help to make a decision I am happy to pay a deposit on an initial test order for 10 units.

Andre