How is the best way to test the finished circuit with full load or is there a better method...

Nope, there is only one bast way.
What did you really mean to ask?

As for your second post, I am not quite sure what you are trying to do at this point.

John

 

Basically I am using the IRS2109 I am triggering it with a 10KHz signal, but I am not seeing anything on the output pins Ho and Lo not sure what I am doing wrong...

Fixed issue with output I'd picked up the reference voltage not vin... Chip was not switched on, but now the outputs are strange...

Why would this be...

The first image shows it working fine pulled up to 13.8V and giving me a nice clean signal, but not so good on the other output...

 

What value electrolytic capacitor would you use between vb and vs... Pins 8 & 6

 

Just died on me, still got a 18.52hz signal on pin 3 of the lm3524 and everything else is working fine but output has vanished... Not sure why...pin 7 has a signal of 8.333khz...

 

This is the signal seen on pin 7... Output is dead, no shortage found, wiring seems ok... No heat detected on chips, can anyone offer any words of advice...

Do not wish to blow any more chips...

 

How stable is the LM3524 only I am not impressed with the way it appears to have suddenly failed on me, I have ordered some replacement parts, but cannot locate a single reason for the sudden failure from both outputs...

I have a tried another chip but is also displaying the same issue, not even a glimmer of a signal, I only have the IRS2109 in circuit no load as such in circuit...

As I no longer have any pcb schematic software and the free issue ones are poor library wise the only way I can upload the schematic is by separate jpeg files from the datasheets...

But this is how I have the project...

 

If your using output pins #12 and #13 to drive a single device (IRS2109), they must be "diode ored". By this I mean a diode in series to each connection to the Hin pin. If not you may be smoking the output of one pin with the other. Both outputs don't turn on at the same time, there is a short 'dead time' from one output to the next. If I remember correctly, one output is good for up to 45% duty cycle, two outputs a good to 90% duty cycle. If your motor speed can live with under 50% duty cycle, your better off using just one output pin, either #12 or #13.

 

Soft question but do believe I have the SD setup incorrectly as I was finding it not working correctly so made a tweak to the circuit... Would that give me similar results?
What voltage should enable/disable that side of things is it 2 volts to disable?

 

Thanks shortbus will look into that, could that be why I was seeing a very strange output from the IRS2109...
downloaded Kicad last night but yet again the library is
empty apart from very basic components need to locate some libraries for it... As I am unable to fully show what I am doing...

 

Just a quick update, I have not blown the chips...

Had one of them magic moments whilst at work today, that I realised what the fault was but was powerless to test the theory until I got home and found that the Shut Down was being enabled, there was 2V present on pin 10 found out that the switch I was using had gone faulty on me so had shut the chip down...

Once I removed the switch full functionality was resumed...

If your using output pins #12 and #13 to drive a single device (IRS2109), they must be "diode ored". By this I mean a diode in series to each connection to the Hin pin. If not you may be smoking the output of one pin with the other. Both outputs don't turn on at the same time, there is a short 'dead time' from one output to the next. If I remember correctly, one output is good for up to 45% duty cycle, two outputs a good to 90% duty cycle. If your motor speed can live with under 50% duty cycle, your better off using just one output pin, either #12 or #13.

Basically shortbus I am just using pin 12 only to output to the IRS2109 will I be ok leaving pin 13 floating?

But why am I seeing this on the one output from the IRS2109?

When the other output on the IRS2109 is like this?

 

Not real sure why your using an H-bridge or even a half bridge in your circuit? You only need a high side switch that is PWMed to control the speed. Without going into the starter motor and making modifications to the brush holders and field windings, the motor will only turn in one direction. Reversing direction of rotataion is the only reason to use a H-bridge. And making a 'quasi' alternating DC current is the only reason for the half bridge.

Yes leaving pin 13 floating is OK, if it is not needed.

 

Not real sure why your using an H-bridge or even a half bridge in your circuit? You only need a high side switch that is PWMed to control the speed. Without going into the starter motor and making modifications to the brush holders and field windings, the motor will only turn in one direction. Reversing direction of rotataion is the only reason to use a H-bridge. And making a 'quasi' alternating DC current is the only reason for the half bridge.

Yes leaving pin 13 floating is OK, if it is not needed.

I was told on this thread that a H-bridge, was the only way to control the motor safely as it's pulling 67A DC... hence the reason for going down this route...

I already have purchased the necessary components so have no option now but to continue down this route for the time being, I have no intention of reversing the motor as this is not required for this application...

Can I use the H bridge to control a high current motor or will this never work?

Never worked on anything higher than 3A so this is new territory for me, hence asking for help?

Just researched the high sided switch, so I can see what you mean... how can I resolve the mess I have got myself into and get this project working correctly?

Can you help me out please?

Just looked at a few but they do not seem to be able to handle the necessary current, highest I have seen is either 40A or 50A for a 12V supply...

 

I was told on this thread that a H-bridge, was the only way to control the motor safely as it's pulling 67A DC... hence the reason for going down this route...

I have been following this thread, but don't remember, nor could I find, a post that said that. Can you point to that errant post? That is not to say that there are not reasons to use a half-H control instead of mosfets plus diodes.

There are safety matters to consider that seem to have been ignored to this point. A 1+ HP motor pulling a strong line at 40 mph or so can create a pretty dangerous situation, if the motor gets stuck on. I think you should put some thought into how you will avoid such a situation. In the old days, one of the battery cables to the winch was positioned across a heavy block of wood, and an ax was kept nearby. There were always two operators; one was for safety.

John

 

Obviously something has got lost in translation somewhere along the lines, not sure how... All that I am interested in at the moment is the basic control circuit to ensure we can actually control the speed of the motor once we have this in place then we can expand the design as it's only a prototype at the moment on veroboard...

 

All other systems only use a push button switch and pulse the motor. As this will be used remotely just you and the bird...

 

So how can safely control a dc series wound motor pulling 67 Amps from a 12 V supply. Only interested in forward motion.

 

I have some original IR Application Hexfet books and they show a controller for 48vdc motor single direction control covering motoring currents up to 200amps.
I am not sure if the app note, App 941B is still avaialble on line?
If you can find it you may be able to adapt it for this use.
Max.

 

I've done this years ago on a couple of projects using starter motors as power. It probably isn't how others would do it but it did work.

The first thing I did was to isolate the ground brushes in the starter. By this you disconnect the brushes that are grounded to the motor frame(internally in the motor) and wire them to another terminal like the positive terminal. This terminal is taken from another starter motor (from the scrap yard). You need to use at least the same gauge/diameter wire that is used on the brush leads themselves. And make sure that you insulate the connections well(a couple of layers of heat shrink tube will work). The motor case will need to have a hole drilled in it to accept the new/extra "ground" terminal.

Doing this will allow you to use a "low side switch" mosfet. This low side switch can then be driven directly from your LM3524 output pins, no mosfet drivers needed, the 3524 is made to do this. With a low side mosfet you don't need to supply any of the bootstrap components to the circuit.

But to do this you must do the ground brush isolation, since the motor frame/case is the ground for the motor. Here is a link to the circuit for the control using a SG3525, which is another version of your LM3524. It also shows the"diode or" that I talked about earlier(see pins 12 - 13). Doing this allows the speed to be controlled from 5% to 90% of full speed of the motor. http://www.wzmicro.com/3525.htm

The amperage of your motor is listed as 'full load' amperage. This means that is what it takes when used to start the car. In what your doing with it, it probably won't be drawing anywhere near that amount. But it's good to plan for that amount of current. You are putting your mosfet(s) on a large heatsink aren't you? And don't forget to use a flywheel diode with a value to match the mosfet current value, this keeps the magic smoke in the mosfets.

Like I said probably not how others would do it, I know this works and even the time to add the ground terminal to the motor makes the rest of the circuit that much simpler. Hope this helps.

 

The first thing I did was to isolate the ground brushes in the starter. By this you disconnect the brushes that are grounded to the motor frame(internally in the motor) and wire them to another terminal like the positive terminal.

.

The answer to this is to make the frame or case positive if it is possible and switch the terminal that normally would be the +ve.
IOW reverse the normal power rail configuration.
Max.

 

Would making the case positive cause the battery to flattern quicker when placed on wet grass... Or would it have no effect...