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    Evaluating total energy usage from just DC voltage and current

    LOL!! You were close with the electric locomotive guess - it's a research project into locomotion based on a new type of electric motor. The power may be 9500W, but it's pulsed so overall the total energy used is fairly small in comparison. OUr system relies on large pulses hence the...
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    Evaluating total energy usage from just DC voltage and current

    We're talking about 50A @ 190V, so the shunt resistor was avoided because of power dissapation. Not only are we talking about heat generation, we're worried about losses in our system. However, re-thinking it I think I'd rather deal with a hot resistor and losses than the problems we're...
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    Evaluating total energy usage from just DC voltage and current

    Yes, nullifying the offset cures the problem. But we have many of months worth of data that needs to have this offset removed manually and that in itself is a problem for us. I haven't come up with a good way of evaluating the offset accurately with an algorithm yet. Any suggestions welcome. In...
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    Evaluating total energy usage from just DC voltage and current

    I'm trying to calculate the total energy usage of a dynamic system that is powered by a bank of lead-acid batteries. My method is simple - log current (using current clamp) and voltage across the battery then post process the logged data - a) For each sample point, Instantaneous Power = V*I...
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    Evaluating energy usage in an H-bridge motor control system

    I use an H-bridge to control a hybrid electric motor and I'm trying to calculate the efficiency by comparing energy used to energy delivered (measured by a torque transducer). I am capturing the voltage and current output of the H-bridge as it flows into to the motor. As you might expect...
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    Sourcing ACS758 hall effect current sensor

    Thanks, gave them a call. Nice girl on the phone, but not too good with Allegro stuff (their computer system couldn't find the ACS758 part at all). They are investigating and will give me a call back soon (hopefully) with the details - will post back when I know more.
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    Sourcing ACS758 hall effect current sensor

    Any good suggestions where I can get hold of the Allegro ACS758 hall effect current sensor in low quantities with short lead times? I'm in Australia, but shipping costs aren't important. I've already tried RS, Farnell and Digikey - all out of stock and long delays before new stock.
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    Problems with DC/DC converters in isolated H-Bridge design

    OK, thanks - I will adjust the circuit so the load is no longer inbalanced
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    Problems with DC/DC converters in isolated H-Bridge design

    As shown in the attached schematic, I have a resistor/LED load across the +/- 15V terminals of the DC/DC to meet the minimum load requirements of the device, however it is the 0V/+15V terminals that I am using to power the VO3120 MOSFET driver. Schematic.pdf
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    Problems with DC/DC converters in isolated H-Bridge design

    DOH - my bad. Its the NMA1215SC, data sheet attached. Murata_DC_DC.pdf
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    Problems with DC/DC converters in isolated H-Bridge design

    I am pulling my hair out since I keep destroying the Murata NMC1215SC DC/DC converters in my CPU controlled H-Bridge design. There is no obvious signs of damage such as heat or smell, they simply stop outputting +/- 15V. Testing out of circuit against a reference device shows they truly are...
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    Sourcing high voltage isolation switch for 150V @ 40A

    Any ideas who might be able to supply a high voltage isolation switch capable of handling a constant 150V @ 40A?? The Jaycar SF2245 ones I selected weren't up to the job and began to melt (I thought they might!!)...
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    Advanced Battery Technologies

    I've recently been doing some work with lead-acid batteries. As most of you know, these things are nuts in terms of the amount of power they can deliver - effectively they are a power supply that can deliver hundreds of amps in a small space of time. The upper limit is only defined by the limits...
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    Cooling a resistor load at 6 to 10kW

    Anyone know a good way of getting hold of a decent transformer oil? We have RS and Farnell here in Oz but neither of them stock any (RS used to but discontinued it)
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    Cooling a resistor load at 6 to 10kW

    Yes, absolutely
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    Cooling a resistor load at 6 to 10kW

    It's amazing that sometimes the most obvious things sometime escape me - an old electric heater is a great source of cheap wirewound resistors!!
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    Isolated ground planes on a MCU controlled high voltage IGBT

    OK, the design has changed a little since I last posted - I've gone for the Vishay VO3120 opto-isolated driver powered by dedicated isolated DC/DC converters. I've attached 2 JPGs - one which shows the general layout and one which zooms in showing how the VO3120s are powered and connected. I'd...
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    Cooling a resistor load at 6 to 10kW

    I have some resistors to cool that I presume are going to get rather hot!! I am using 6x wirewound resistors in parallel to create a 3.75 Ohm load for a 150V source, hence generating 40A and 6kW. Later I may up the voltage to 200 so I need to spec the cooling for a max of 10kW. Each wirewound...
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    Isolated ground planes on a MCU controlled high voltage IGBT

    OK, I've been pointed to the existence of linear optocouplers to solve this problem! You learn something new everyday.... Having decided to go down the opto-isolator route, I'm struggling with the logistics of powering the IGBT-side of the opto-isolator. To elaborate, there are actually 4x...
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    Isolated ground planes on a MCU controlled high voltage IGBT

    What if I used an opto-coupler instead?? The switching frequency is only around 10Hz, but reaction time has to be within 1ms - I think a good opto-coupler could achieve this. If I used an opto-coupler, the only remaining problem is what to do with the ground for the resistor-divider voltage...
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