HDC2450 Power output

Well i got my controller working and all hooked up, but i\'m not getting the performance I was expecting. The motors i\'ve used I know will pull tons of power if allowed, their stall is around 120 amps each, there are 2 of them. During my last test, i was having issues getting them to pull more then 30 amps each, i wrote some code to output all the internal temperature, amps, applied power:

vals: -0.000000 -0.000000 ? V=135:370:4918 BA=0:0 A=0:0 M=0:0 P=0:0 T=30:40:40:28:32
vals: -0.000000 -0.000000 ? V=135:370:4914 BA=0:0 A=0:0 M=0:0 P=0:0 T=30:40:40:28:32
vals: -0.200000 0.060000 ? V=133:370:4915 BA=10:0 A=50:0 M=110:0 P=44:0 T=30:40:40:28:32
vals: -0.400000 0.185577 ? V=118:368:4853 BA=90:40 A=475:200 M=333:94 P=134:60 T=30:40:40:28:32
vals: -0.600000 0.385577 ? V=125:366:4791 BA=150:135 A=717:725 M=554:316 P=223:149 T=30:39:40:28:32
vals: -0.800000 0.585577 ? V=127:359:4795 BA=400:315 A=1363:1550 M=776:538 P=315:165 T=30:39:40:28:32
vals: -0.999969 0.785577 ? V=126:358:4818 BA=320:315 A=1475:1550 M=998:760 P=202:147 T=30:39:40:28:32
vals: -0.999969 0.985577 ? V=119:360:4934 BA=285:275 A=1500:1400 M=998:982 P=178:186 T=30:39:40:28:32
vals: -0.999969 0.999969 ? V=124:358:4643 BA=295:280 A=1550:1350 M=998:998 P=157:188 T=30:39:40:28:32
vals: -0.999969 0.999969 ? V=124:358:4369 BA=280:295 A=1450:1400 M=998:998 P=160:181 T=30:39:40:28:32
vals: -0.999969 0.999969 ? V=127:351:4930 BA=280:310 A=1450:1500 M=998:998 P=169:188 T=30:39:40:28:32
vals: -0.999969 0.999969 ? V=121:349:4805 BA=280:270 A=1350:1350 M=998:998 P=176:207 T=30:39:40:29:32
vals: -0.999969 0.999969 ? V=129:359:4761 BA=290:265 A=1375:1317 M=998:998 P=174:213 T=30:39:40:29:32
vals: -0.999969 0.999969 ? V=123:356:4600 BA=305:265 A=1550:1262 M=998:998 P=163:209 T=30:39:40:29:32
vals: -0.999969 0.999969 ? V=118:351:4929 BA=280:335 A=1425:1560 M=998:998 P=176:204 T=30:39:40:29:32
vals: -0.999969 0.999969 ? V=117:358:4762 BA=265:345 A=1375:1535 M=998:998 P=183:212 T=30:39:40:29:32
vals: -0.999969 0.999969 ? V=121:351:4869 BA=275:275 A=1425:1318 M=998:998 P=182:228 T=30:39:40:29:32
vals: -0.999969 0.999969 ? V=117:358:4618 BA=280:320 A=1425:1475 M=998:998 P=177:207 T=30:39:40:29:32
vals: -0.999969 0.999969 ? V=120:357:4587 BA=280:355 A=1400:1628 M=998:998 P=179:204 T=30:39:40:29:32
vals: -0.999969 0.999969 ? V=119:351:4647 BA=275:305 A=1350:1409 M=998:998 P=176:235 T=30:39:40:29:32
vals: -0.999969 0.999969 ? V=117:358:4762 BA=280:265 A=1350:1285 M=998:998 P=174:222 T=30:39:40:29:32
vals: -0.999969 0.999969 ? V=129:357:4742 BA=300:280 A=1425:1268 M=998:998 P=173:213 T=30:39:40:29:32
vals: -0.999969 0.999969 ? V=125:354:4395 BA=305:365 A=1450:1565 M=998:998 P=175:232 T=30:39:40:29:32
vals: -0.999969 0.999969 ? V=121:356:4941 BA=290:300 A=1425:1351 M=998:998 P=179:241 T=30:39:40:29:32
vals: -0.939970 0.939970 ? V=118:349:4693 BA=315:285 A=1475:1250 M=932:932 P=178:236 T=30:39:40:29:33
vals: -0.739970 0.739970 ? V=130:355:4792 BA=310:405 A=1475:1638 M=710:710 P=179:219 T=30:39:40:29:33
vals: -0.539970 0.539970 ? V=125:355:4562 BA=315:335 A=1500:1448 M=488:488 P=176:242 T=30:39:40:29:33
vals: -0.339970 0.339970 ? V=127:353:4607 BA=310:285 A=1550:1239 M=266:266 P=172:242 T=30:39:40:29:33
vals: -0.139970 0.139970 ? V=127:354:4918 BA=310:345 A=1550:1513 M=44:44 P=169:220 T=30:39:40:29:33
vals: -0.000000 -0.000000 ? V=122:350:4836 BA=375:515 A=1900:2546 M=0:0 P=128:183 T=30:39:40:29:33
vals: -0.000000 -0.000000 ? V=119:347:4832 BA=270:280 A=1350:1500 M=0:0 P=124:111 T=30:39:40:29:33
vals: -0.000000 -0.000000 ? V=120:344:4641 BA=290:275 A=1425:1400 M=0:0 P=119:121 T=30:39:40:29:33
vals: -0.000000 -0.000000 ? V=116:357:4837 BA=310:280 A=1475:1375 M=0:0 P=113:118 T=30:39:40:29:33
vals: -0.000000 -0.000000 ? V=123:355:4835 BA=310:315 A=1575:1525 M=0:0 P=106:106 T=30:39:40:29:33
vals: -0.000000 -0.000000 ? V=121:351:4823 BA=90:105 A=400:475 M=0:0 P=37:40 T=30:39:40:29:33
vals: -0.000000 -0.000000 ? V=135:365:4913 BA=0:0 A=0:0 M=0:0 P=0:0 T=30:39:40:29:33
vals: -0.000000 -0.000000 ? V=135:365:4917 BA=0:0 A=0:0 M=0:0 P=0:0 T=30:39:40:29:33

This log is for about a second, maybe 2 seconds. Now obviously you can see the P= shows that it\'s limiting how much power will go out. This is the last part of the log, in the beginning though when the motor controller was cold, it said P=900 and still it wouldn\'t pull over 30 amps. Regardless, does the temperature reported seem high? normal? average. I was only pulling 30amps per channel for a total of 15 seconds over the span of 2-3 minutes. After that you see what I have above.

This is far from the 120 amp limit, perhaps the over resistance of 100% throttle is simply to high for these motors to pull over 30 amps with these controllers, i don\'t know how to even check that.

I got it upto 40 amps i think once or so. I also verified these amp currents with a secondary external amp guage which I watched the entire current going into the controller, the values seem pretty accurate.

I know 120 amps is momentary, but it does say 80amps for an hour, i think that\'s for the 150amp model, so this modal would be 65amps for an hour? So 30 amps is kinda far from that, especially after 30 seconds.

My application is a skid steer setup, the log above is when I do a skid steer, taking the most power. Motors don\'t show negative because my setup is a hydraulic system, direction is controller elsewhere.

Any ideas on how to get more power?

Thanks,
Ross

What do all of the variables represent, and what are their units? Am I correct in reading that \"BA\" is the battery current, and \"A\" is the motor current? If so, it appears that your motor current is well above 120 amps momentarily, and is being throttled back to the current limit. PWM current limiting allows a much higher motor current than you see when measuring the battery current.

BA= is battery amps for each channel, but 100 means 10 amps, they add an extra 0, so whatever it says, divide by 10. So you can see my peak was 400, which is 40 amps, but that was for less then 100 milliseconds.

All that output is the output from the microcontroller directly, the documentation goes over how to interpret all the values. A is total amps, but not really, i\'m not sure why that value even exists, it\'s the amps pulled while the H-bridge is active... but in the case below, 150 amps when it\'s only 18-20% active is 30 amps.

the temperature feedback is all in celsius, so that\'s easy, ant 40 degrees IMO is not very hot, yet at that temperature it decided to kickback. Most power mosfets are rated to pretty high running temperatures, so i\'m not really sure why the power was scaled back so much, that\'s why i posted a question.

Touching the controller felt warm, but was not uncomfortable, i could of held my hand there forever.

Although the H-bridge may be delivering an 18% to 20% duty cycle, the motor current may average 150 amps while the battery current averages 40 amps. This is not specific to the roboteq controller, but is inherent to any motor controller that uses PWM to hold a current limit. The 150 amps is not present as a discontinuous current that flows only 20% of the time, it exists as a continuous current with some ripple. The PWM duty cycle is scaled back to provide an average voltage that would allow 150 amps to pass through the load presented to it.

My understanding is that the amp rating of the Roboteq refers to the motor current, not the battery current.

I would expect that if you re-gear the system with a higher reduction you will see a larger battery current and more mechanical power.

In the log you will see 2 amps value: BA is battery amps, A is motor amps.

You can see that in some areas, the motor amps is hitting the 150A limit (A=1550) and even peaking at 190A.

See the section in the user manual that explains the battery amps vs motor amps.

What is happening here is that your motor is a very large load to the controller:

Battery is 48V
Applied power is ~180/1000 = ~18%

So the motor sees 8.6V (48V * 18%)

Yet is consumes 150A. Depending wether the motor is spinning or stalled, this means the controller sees a resistor that could be as low as 57mOhm.

There is no easy way out. You can change your gear ratio to reduce the mechanical load or use two controllers in single channel mode.

Well, i\'ve read the motor current vs battery current, in reality, every other H-bridge on the planet would count BA battery amps as the power output. Yes, with a 20% active H-Bridge, during that 20% period the motor is pulling 5 times the average current, i mean it\'s basic mathmatics. I don\'t really want to get into a debate over terminology. It comes down to the fact that when I command the controller to do 100% throttle, regardless of scaling, the average amp output that the motor sees is 30-40 amps (it\'s not stalled during these tests, spinning at low RPM however).

Here are some values with a dead cold controller, as you can see by the temp values:
vals: -0.999969 0.999969 ? V=129:354:4694 BA=275:360 A=1394:1520 M=998:998 P=215:236 T=13:10:11:9:10
vals: -0.999969 0.999969 ? V=125:351:4237 BA=305:355 A=1425:1456 M=998:998 P=203:254 T=13:11:11:9:10

So temperature isn\'t the issue. See here\'s my concern, i would buy the larger single channel controller, but if the 120amp controller only gets 30-40 amps, i\'m to assume the 300 amp controller is going to do 75-100 amps?

The only argument that makes sense to me, is the motor amps is 150 amps when the motor is active on the H-bridge, since this is to much for the controller it simply kicks out, and that is why it\'s kicking out, it\'s just to much current and it won\'t even try because it\'s afraid it will harm itself. With a larger controller, 150 amps won\'t hit it\'s internal limit, and therefore be able to push the throttle to 100%. Is that correct at all? meaning a 300 amp controller will be able to get much closer to 300 amps ? I really doubt i\'d goto 300, and i don\'t want to really, perhaps the 150amps above is what it is going to pull through most of it\'s rpm range.

I believe i have the HDC2450 bare, not the HDC2450H (high current, i think that\'s the abbreviation) I\'m thinking I should get 2 HDC2450HS, high current single channel, that woudl be rated at 300 amps right? The website doesn\'t allow me to buy these, i don\'t see that link, should i just call?

Thanks,
Ross

It is true that most controllers measure the battery amps. Our AX family works this way too.

However, the motor amps are what matter. The current that flows throug the motor, does also throught the wires and mosfets. The amount of energy that is disipated by the mosfets is based on that current.

With this kind of load, it is easy to see how a 50A controller would eventually smoke when 150-200A flows throught the transistors, while battery current never exceeds the controllers published rating.

The HDC2450 may be over cautious cutting down the throttle when motor amps reach 150A but this is how it is designed to work.

A single channel version would not have this problem in your case because the amps limit would kick in at 300A instead of 150A. At that level, the power level is more likely to be at 50% rather than 20% now. So the spread betwen the battery and motor amps will not be as high as what you have now.

Before you switch to single channel controller, if you ahve a clamp DC ampmeter, you may want to measure the motor amps to make sure that it is in line with what the controller is reporting.

You can convert your existing HDC into a single channel version by uplading a different logic mapping file we would send you.

Tell me, with the same controller, and a 45v battery (lithium) on my latest powerchair here

www.wheelchairdriver.com/BM-MK3-lithium-battery-powerchair.htm

Am I going to have the same problem? I need at least 120 amps (measured with my clamp meter) to each motor.

The stall current is over 120 amps, and probably a good bit more. Motors draw at least 120 amps stalled at 12v I think.

Mobility controllers just limit current (by limiting volts) to their rated 100, or 120 amps per motor.

Thanks. Otherwise my expensive project is screwed!

>>> The HDC2450 may be over cautious cutting down the throttle when motor amps reach 150A but this is how it is designed to work.

Surely it should throttle back to its 150 max? At least thats what I expected?

Added... The link on your site to the forum no longer works.

On the left. <<<

You may experience the same problem if your motor has a very low impedance. In this case, you may have the motor pulling over 150A while the battery amps is a lot less.

Not knowing the specifications of your motor, it is not possible for us to predict. However, if these are wheelchaire motors (even if powerful ones) in all likelyhood you will be OK.