Short time ago I was talking to John (Mercuriell) about reviewing some common ESCs, comparing their features, price, and performance at full and partial Throttle with varying loads. He happily offered his Kosmik 200 to include in the test, and I couldn't resist.
Over the next week or so I plan to:
1) Compare ESC cost and basic features
2) Do a complete teardown and review of the internals including an estimate HW cost.
3) Performance comparison at Full throttle (100% Duty cycle) @ 50% of the rated input current
4) Performance comparison at Partial throttle (50% Duty cycle) @ 50% of the rated input current
5) Transient load tests, from 0% rated input current to 100% of the loaded input current.
I'll also be getting into some technical explanations on how Active free-wheeling 'AFW' works, and how it affects ESC and motor performance. Also be discussing how motor inductance affects motor power, how to choose your ESC PWM frequency and timing and why low inductance motors, eg double-Wye (YY) connected, are key for high power applications.
I'll be including the ICE2 HV160 + HV80, YGE120HV, KOSMIK 200, PowerJive 120, Turnigy Dlux 80, and possibly a SJ Hawk 120.
1) Kontronik Kosmik 200
2) YGE 120HV
3) Active Freewheeling
4) HW review of the Castle ICE2 ESCs
5)
Video - Full & Partial throttle tests of Kosmik and CC ICE2 HV 160
Ill be tearing them apart, posting up some photos, will briefly discuss the internal components, compare the HW including HW cost. Ill also be including oscilloscope snapshots of the phase voltages at full and partial throttle, show you how timing advance works, and compare motor RPM (Some say the YGE produces more RPM for the same input voltage and motor Kv).
Close up of the Kosmik. This has 10A/30A Cont/Burst BEC. Im going to stress test the BEC to see if itll handle the rated current.
Ill be using my Dyno as a load. The dyno consists of a custom made Scorpion HK4535, and a Hk4035-560Kv..
Close up of the dyno
The Dyno works by having one motor connected to the ESC, and the other motor (used as a generator) connected to a variable load bank. The output voltage gets rectified into DC, then dissipated into a MOSFET load bank. The load can be varied by varying the amount of current i draw from the generator. I used this dyno to test my 24S ESC and it worked like a treat.
Ill be uploading the results and videos to this thread as i progress through the work. stay tuned...
Feel free to throw in some ideas/comments...
Kontronik KOSMIK 200
Ok... I thought id start with a tear-down of the KOSMIK as many of you would be eagerly waiting to see the internals.
SHORT DESCRIPTION:
The KOSMIK 200 is probably the largest (and most expensive) RC ESC i have seen to date. Physically, Its quite large and heavy, however, this monster ESC is not designed for small machines. If your considering this ESC, you're probably building a 700 sized speed machine, or 800 sized hardcore 3D rig.
One thing you'll notice is that the wires are connected onto the ESC with tabs and M5 nuts and bolts, rather than solder. I do prefer nicely soldered connections, however soldering such large wires would be quite difficult..
SPECS:
14S @ 200Amps continuous.
200Grams without cables, 310grams with cables/connectors/screws.
Active free-wheeling
8-32Khz PWM
Hardware:
Main controller: STM32 32Bit CPU @ 120Mhz
FET: International rectifier IRF7759
http://www.irf.com/product-info/data...uirf7759l2.pdf
FET drivers: International rectifier IRS2186
http://www.irf.com/product-info/data...irs2186pbf.pdf
BEC Regulator: National Semiconductor LM5116
https://www.national.com/ds/LM/LM5116.pdf
Price:
$809 @ Readyheli
INTERNALS:
The KOSMIK consists of 3 x PCBS. We have a Logic PCB (the brains), a MOSFET driver and BEC PCB, and the Power PCB. They are all connected using 0.05' and 0.1' SMD pin headers.
STM32 main controller. Enough proccessing power to mine bitcoins here.
The BEC circuit consists of a National Semiconductor LM5116 synchronous regulator IC, a 10uH SMD high frequency inductor, 3 x 80Volt SMD FETs and a diode + capacitors. The synchronous design is required to keep temps cool at high input/output voltage ratios. FETs are used instead of free-wheeling diodes (which have a large voltage drop when conducting). I have yet to test it, but i have no doubt it'll hold up to the 10Amp continuous current rating.
Normally you'd only find 3 x FET drivers in a BL ESC. However, Kontronik have chosen to double that, and use 6 x FET drivers in the KOSMIK. When switching FETs at high Speed (high slew rates), and high frequency the FET gates do begin to draw a considerable amount of current, and begin to stress the drivers. It looks like they've added an extra driver, giving us 2 x drivers per phase, sharing the load. Good thinking.
The IR2186 is currently the most powerful Hi/LO FET driver in a SOIC8 SMD package. Having a robust driver is crucial in high current, high stress applications, because if the driver fails, there is the possibility of the upper and lower FETs conducting and causing shoot-through (or cremating
), as we saw in the previous ICE HV series...
I'm guessing the power PCB is at least a 4 layer @ 4oz copper.
We have current sensing shunts on each phase. This hints the possibility of future updates that include SINUSOIDAL or FOC commutation.
The FETs used are rated at a whopping 160Amps continuous each. With only 1.8mR resistance and 8 x FETs on each phase, we can see where the KOSMIK gets its 200Amp rating from.
There is an additional FET near the input terminals. This is the key element in the anti-spark circuit, connecting the capacitors to the main supply slightly after power up.
All the semiconductors are well known brands, and there is clearly no skimping on quality anywhere. Even the PCB is high grade. But does it justify the $800 asking price?? With roughly $200 in component cost (not including the CNC case, assembly and engineering) we are going to have to wait and see how it performs..
Next up the YGE 120 HV !!