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DC motor driver

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learnfromfailures:
I'm designing a new motor driver for a DC motor which has starting peak current of 30A and 28Volts power supply. Previous engineer used an integrated motor driver IC solution (VNH3SP30-E) that has a MOSFET (Full H-bridge) inside an IC. There are so many customer complaints that it is blowing up in the field. When I look at the IC there is not good separation and everything things runs off the high power line. I dont know what is the advantage of using a integrated driver solution over original MOSFET/IGBT approach. I personally think having external FETs would be a safer approach. Has any one used the integrated solutions before ? if yes, is it better than original power electronics. I'm trying to see which is a better approach.

fourtytwo42:
IMOP you need to find out why the existing circuit is failing before attempting to redesign it. What do you mean by "When I look at the IC there is not good separation and everything things runs off the high power line" ?
You say nothing about the application now how the IC is protected against overvoltage or motor braking, also the pcb layout is critical to provide adequate heatsinking and of course manufacturing need to actually be soldering it down properly!
An integrated solution provides much more sophisticated protection than you can realise in a discrete design and the latter will also be much much bigger and more expensive, likely as not it will blow up too for the same reason the chip is failing now.

Psi:

--- Quote from: fourtytwo42 on June 15, 2021, 10:38:34 am ---IMOP you need to find out why the existing circuit is failing before attempting to redesign it.

--- End quote ---

+1 for this.

I've found ST power electronics to be very reliable.
I used to have issues with a mosfet based solenoid PWM solution blowing up, so I moved to an ST integrated high-side driver chip (VN5E010) and have not had a single one explode since.

So if you are blowing up an automotive rated VNH3SP30 you probably need to figure out why before trying to replace it.

If I had to take a blind guess, the solution to stop it blowing up is probably going to be adding a big TVS diode or cap somewhere.  The VNH3SP30 is probably getting motor spikes over 40V.

learnfromfailures:

--- Quote --- IMOP you need to find out why the existing circuit is failing before attempting to redesign it. What do you mean by "When I look at the IC there is not good separation and everything things runs off the high power line" ?
--- End quote ---
This is the new job I started and I'm still trying to investigate. One reason I heard that the IC is blowing up because of back emf which was around 90V. So another engineer added a clamping solution (TVS diode & resistors) to absorb the back emf. They can't send this back to the battery. Another reason I saw, the peak current is 30 Amps (+10% overhead) at 650in-lb of torque from load. The IC is rated for max 30Amps peak current and I think previous engineer should have picked an IC H-bridge that can handle close to 3x Voltage, Current, and Heat-Dissipation-Ratings of the system.


--- Quote ---  "When I look at the IC there is not good separation and everything things runs off the high power line" ?
--- End quote ---
The chip is powered off the main power supply and there is no filtrations(see the attached schematic).  Any large transient on the power supply would probably blow it.

learnfromfailures:


--- Quote ---I used to have issues with a mosfet based solenoid PWM solution blowing up, so I moved to an ST integrated high-side driver chip (VN5E010) and have not had a single one explode since.
--- End quote ---
Thanks for sharing that, VN5E010 has higher tolerance than VNH3SP30
Max supply voltage           VCC 41 V
Operating voltage range    VCC 4.5 V to 28 V
Current limitation (typ)     ILIMH 85 A


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