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  • Author Author: balearicdynamics
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Meditech: Powering the unit

balearicdynamics

Powering Meditech

As Meditech is almost complex several power levels should be provided. To simplify the scenario the elements that should be powered in the base architecture are listed below

 

  • Storage: hard disk(s) will be low power 2.5 inches devices but it is to exclude the adoption of some kind of static SDD due the too high price per gigabyte. Maybe in the future these prices dramatically decrease so this kind of reliable solution become affordable.
  • Processor units (at least two): we should take in account that the RPI devices are equipped with some add-on electronic that consumes power too, e.g. Wi-Pi, ChipKit PI and other custom interface components.
  • Probes: should be powered to operate and not always it is possible to adopt low-energy profiles, as in the case of the blood pressure that should be equipped with  a reliable yet small air-pump.
  • Thermal printer: not used continuously, this device power consumption affect the system power performances.
  • Network switch: just another power-consumption device.

 

Power supply architecture

The more reliable solution I can see is the adoption of a multiple power-source solution:

 

  • A small ATX power supply gives the power when a 110-240V AC source is available. When Meditech is powered with AC the internal battery is under charge, despite if it is in use or not.
  • A car 12V power plug converter to be used for normal work and battery charge should be available as an alternative to the ATX power suppply
  • A laptop 18V CC should be sufficient to power all the components for a reasonable period of time (at least 2-4 hours)

 

Until now it should be possible to provide only +12V and +5V to power the entire system. A dedicated power control unit, including power level indicator and some logic, current regulators and battery to main power switch should be designed.

 

Add-on modules

As mentioned in some previous post the Meditech architecture can host add-on modules. To avoid to limit the module usage due to power limitations, especially when the system is used outdoor and is battery-operated, every module should include an autonomous battery powering system that is under charge when the module is connected to the main device and an external power source is provided.

  • in reply to mcb1

    Mark I hope... Anyway this is the first phase, putting the pieces together then after this first level assembly I will go in depth on every part. Thanks for following.

     

    Enrico

  • in reply to balearicdynamics

    Fair enough.

    If you do go past the initial stage I'm certain Simon Leuz at Wurth http://www.element14.com/community/people/sleuz could assist.

     

    Mark

  • in reply to mcb1

    Mark, I exclude this option for a lot of reasons.

     

    The first is that the device need more separated low level power: printer will work at 7,5-12 VCC, RPI at at different power, hard disk and so on. Then there is a general problem of recharging time. Not last, you should also consider that Meditech it is a box with many functions in it, an internal network, differentiated hardware and so on. I am not expert in wireless charging but I think it's hard to put the equivalent of 18,5 or 27 VCC laptop battery on a wireless charger ...

  • in reply to balearicdynamics

    You may wish to look at using Wireless Charging.

    http://www.element14.com/community/community/design-challenges/wireless-power-ii

     

    This does solve many issues, and some power banks have wireless charging inbuilt.

     

    Mark

  • in reply to michaelkellett

    Hello Michael,

     

    thank you for your suggestions. One of the reasons of this isolate post was just to start a discussion. About this aspect, I agree with you and I am already aware of this potential limitation but if you read in detail the ATX (or any other kind of powering system is NOT the power unit of the device itself that will be battery powered (and I anticipate also a solar power support).

     

    As a matter of fact the ATX power will be used for charging purposes only, and it is almost obvious as it is to be used as a portable device. In the meantime there will be a twin unit that will work in a hospitalised structure to give support to the remote operator working on-field. This unit has not probes attached but includes support features. In the case of the use of indoor applications the unit will be provided with a medical standard-aligned powering system that it is not the worth to use in the prototype device.

     

    I have mentioned about the uses here:

     

    • A small ATX power supply gives the power when a 110-240V AC source is available. When Meditech is powered with AC the internal battery is under charge, despite if it is in use or not.
    • A car 12V power plug converter to be used for normal work and battery charge should be available as an alternative to the ATX power suppply
    • A laptop 18V CC should be sufficient to power all the components for a reasonable period of time (at least 2-4 hours)

     

    With the sentence "despite if it is in use or not" I mean that while is under charge the unit can receive data, exchange information with the display unit and other "administrative" tasks. The same will occur with the car  power converter. In this case (thinking on ambulance) it is simpler to follow the medical standard specifications.

     

    The last though, but I had not yet had time to update this post, about the AC power (better recharge) unit, is that is can be a removable one so only when it is needed the AC box can be slide inside the Meditech container. This can save about 100-200 gr. of weight when moving the unit. The powering unit board (directly interfaced to the AC power supply) will act also as a switch disabling any health probe when the system is under charge.