Search found 831 matches

by Njay
Jan 22 2019 7:40am
Forum: E-Bike Technical
Topic: Automatic anti spark circuit
Replies: 23
Views: 6514

Re: Automatic anti spark circuit

Vgs will reach Vbat * R2 / (R1 + R2), so at 42V it will reach 17V.
The resistive divider shown for the 36V system scales Vbat to ~40.5%
by Njay
Nov 09 2018 3:43pm
Forum: Motor Technology
Topic: High side vs Low side PWM
Replies: 74
Views: 7253

Re: High side vs Low side PWM

You should scale down and then go up slowly. I think I've never seen a controller with PWM frequency above 32KHz for these power levels. If I read your last scopeshots correctly, the FET is not even having time to reach the final gate voltage before the cycle ends. Do you need 100KHz? What's the imp...
by Njay
Oct 21 2018 8:00pm
Forum: E-Scooter and Motorcycle General Discussion
Topic: Hub motor wheel seizing after a few Km
Replies: 7
Views: 695

Re: Hub motor wheel seizing after a few Km

I don't know, he decided to sell the motorcycle as is and bought an electric BMW.
by Njay
Sep 12 2018 5:25pm
Forum: E-Scooter and Motorcycle General Discussion
Topic: Hub motor wheel seizing after a few Km
Replies: 7
Views: 695

Re: Hub motor wheel seizing after a few Km

Ok guys, thanks for the help. I'm going to pass on the information, let's see what will be found.
by Njay
Sep 11 2018 6:08am
Forum: E-Scooter and Motorcycle General Discussion
Topic: Hub motor wheel seizing after a few Km
Replies: 7
Views: 695

Re: Hub motor wheel seizing after a few Km

Thanks dust, but it is mechanical, that is, when it blocks, it blocks, it's not like a shorted motor resisting spinning, it just blocks and you're not able to spin it at all.
by Njay
Sep 10 2018 1:13pm
Forum: E-Scooter and Motorcycle General Discussion
Topic: Hub motor wheel seizing after a few Km
Replies: 7
Views: 695

Hub motor wheel seizing after a few Km

Hello All, A friend of mine has a chinese electric scooter (9KW hub motor) whose rear wheel started to seize after a few Km, it looks like it seizes due to warm up. Letting it cool a little it will spin freely again. I made a few searches but couldn't find anything similar, maybe I'm not using the r...
by Njay
Jul 18 2018 6:57pm
Forum: Endless-Sphere Wiki
Topic: How many of you really use the wiki?
Replies: 74
Views: 12937

Re: How many of you really use the wiki?

I guess Wordpress (almost "barebones", avoiding install of N plugins etc etc) is a flexible platform with easy (and shareable) management.
by Njay
Jul 03 2018 5:26pm
Forum: Endless-Sphere Wiki
Topic: How many of you really use the wiki?
Replies: 74
Views: 12937

Re: How many of you really use the wiki?

Forums are discussion tools, but absolutely terrible to find information. If we want ES to be something more than a discussion place, we need to have an information consolidation area, and a search exclusive to that area. What platform doesn't really matter as long as it's easy & quick to use (creat...
by Njay
May 16 2018 2:14pm
Forum: Motor Technology
Topic: Lebowski's motor controller IC, schematic & setup, new v2.A1
Replies: 1794
Views: 202646

Re: Lebowski's motor controller IC, schematic & setup, new v2.A1

Some micros (even 8bit ones like AVRs) have an optional differential amplifier before the ADC.
by Njay
May 16 2018 12:30pm
Forum: Motor Technology
Topic: Lebowski's motor controller IC, schematic & setup, new v2.A1
Replies: 1794
Views: 202646

Re: Lebowski's motor controller IC, schematic & setup, new v2.A1

Phase inductance should be different depending on rotor position. If that's enough info, and "easily" measurable, to know the exact rotor position, it's another story. Maybe it's also possible to use a phase to induce current into another phase and from that get position information.
by Njay
Jan 28 2018 6:33pm
Forum: Motor Technology
Topic: OSHW TO247 IGBT watercooled laminated half-bridge
Replies: 144
Views: 20370

Re: OSHW TO247 IGBT watercooled laminated half-bridge

In the controller I mentioned I have it in the DC link caps - low FET source. When I talked about this in another thread, HH just said above 10KW you don't want to add any source inductance.
by Njay
Jan 26 2018 2:18pm
Forum: Motor Technology
Topic: OSHW TO247 IGBT watercooled laminated half-bridge
Replies: 144
Views: 20370

Re: OSHW TO247 IGBT watercooled laminated half-bridge

Another effect I initially noticed on my controller that didn't seem to make sense was that the FET switching speed was not increasing after a certain point while reducing the gate resistor. That's because of the negative feedback with the stray source inductance, which "clamps" di/dt.
by Njay
Jan 26 2018 1:45pm
Forum: Motor Technology
Topic: OSHW TO247 IGBT watercooled laminated half-bridge
Replies: 144
Views: 20370

Re: OSHW TO247 IGBT watercooled laminated half-bridge

Concerning gate driver overshoot protection ... again :lol: Does someones knows about this active clamping technique from TM4? https://www.tm4.com/wp-content/uploads/2014/03/ATZelektronik_05_2012_scientific_article_TM4_power_electronics.pdf It seems that it might be difficult to make it work proper...
by Njay
Jan 18 2018 2:04am
Forum: Motor Technology
Topic: Power PCB for Lebowski Controller to be combined with Bobc's processor board
Replies: 201
Views: 19298

Re: Power PCB for Lebowski Controller to be combined with Bobc's processor board

minimum wrote:
Jan 18 2018 12:11am
Solderable "dummy pins" (from 2.54mm male-male SIL headers) to conserve PCB space?
Looks like a good idea until you need to take out the board for some rework or repair...
by Njay
Jan 17 2018 5:04pm
Forum: Motor Technology
Topic: Power PCB for Lebowski Controller to be combined with Bobc's processor board
Replies: 201
Views: 19298

Re: Power PCB for Lebowski Controller to be combined with Bobc's processor board

You pull the tracks a little to the left, even just making them make half roundabout, making space for the holes.
by Njay
Jan 12 2018 5:55am
Forum: Motor Technology
Topic: Power PCB for Lebowski Controller to be combined with Bobc's processor board
Replies: 201
Views: 19298

Re: Power PCB for Lebowski Controller to be combined with Bobc's processor board

I would make the phase track leave the middle of the top/bottom track instead of from one of the FETs.
by Njay
Dec 05 2017 2:18pm
Forum: Motor Technology
Topic: Power PCB for Lebowski Controller to be combined with Bobc's processor board
Replies: 201
Views: 19298

Re: Power PCB for Lebowski Controller to be combined with Bobc's processor board

Sometimes the TO-247 versions are beefier at the bounding wires.
by Njay
Oct 30 2017 7:05am
Forum: Motor Technology
Topic: High side vs Low side PWM
Replies: 74
Views: 7253

Re: High side vs Low side PWM

I have my doubts that changing to copper will reduce your spike... because it's the inductance that makes the spike, not the resistance. Here's a diagram from another topic, just for reference as a half-bridge diagram with the parasitic inductors; the top FET (M2) is being used as a diode but it's f...
by Njay
Oct 27 2017 7:35am
Forum: Motor Technology
Topic: High side vs Low side PWM
Replies: 74
Views: 7253

Re: High side vs Low side PWM

You need to reduce the switching speed on both sides. Will you need a 50 Ohm resistor? A 100 Ohm? A 500 Ohm? I don't know, you'll have to go up until switching speed comes down to cause acceptable voltage spikes/ringing. You can also add a capacitor in parallel with G-S. You can control switch on an...
by Njay
Oct 27 2017 4:15am
Forum: Motor Technology
Topic: How to describe PMSM/BLDC base speed?
Replies: 6
Views: 1340

Re: How to describe PMSM/BLDC base speed?

qaz33 wrote:In every PMSM/BLDC motors for industry purpose you can find one just next to the kV info.
Because voltage "doesn't" change (mains), I guess.
by Njay
Oct 27 2017 3:55am
Forum: Motor Technology
Topic: High side vs Low side PWM
Replies: 74
Views: 7253

Re: High side vs Low side PWM

You are switching really fast for that amount of current. Let's put things in perspective: dv = L di/dt di = 250A dt = 40ns A small piece of 10mm wire has like 10nH inductance just for some reference. Let's assume your layout has 5nH parasitic inductance from the FET to the phase output alone. That ...
by Njay
Oct 26 2017 12:46pm
Forum: Motor Technology
Topic: High side vs Low side PWM
Replies: 74
Views: 7253

Re: High side vs Low side PWM

A) One phase of the motor is being driven with synchronous rectification. This is the high side, it is switching in a synchronous manor to control the speed of the motor. There is dead time between the high and low side switching. Nope. The "high side" cannot be driven in "synchronous rectification...
by Njay
Oct 26 2017 8:14am
Forum: Motor Technology
Topic: High side vs Low side PWM
Replies: 74
Views: 7253

Re: High side vs Low side PWM

When you close a switch you're stopping current from flowing through an inductance (in the context of this thread, a parasitic inductance). If you sit down and draw your power bridge's schematics of the power paths, including the (parasitic) inductors on all connections, and do the exercise of simul...
by Njay
Oct 26 2017 6:17am
Forum: Motor Technology
Topic: High side vs Low side PWM
Replies: 74
Views: 7253

Re: High side vs Low side PWM

At switch off. As you try to cut the current on an inductance, it raises the voltage trying to counter act.
When the FET is ON, its Vds is very low.
by Njay
Oct 25 2017 8:52am
Forum: Motor Technology
Topic: KT motor controllers -- Flexible OpenSource firmware for BMSBattery S/Kunteng KT motor controllers (0.25kW up to 5kW)
Replies: 3695
Views: 252177

Re: OpenSource firmware BMSBattery S/Kunteng KT controllers

FWIW, and that's just a remark, because I don't know anything, I do notice a very pronounced absence of the C keyword "volatile" in the firmware C source code (git repo search). I keep reading about interrupts and global variables all the time, though, which we would indicate that volatile would ra...