Hi,
After solving the grounding issues i had with this schematic
i came to realize that i need the motor to stop as quickly as possible, i searched the forums and found the answer was probably a half H bridge, though all the designs i found through the forum were for full h bridges and most seemed not to work,
Im looking for the simplest way to introduce fast motor braking with the above schematic, that will not melt
or maybe just a simple design for a half H bridge that can be switched from power to braking with as little delay as possible.
Hi mark, thanks for the reply. its actually 12v max and engine stall of about 10A, i appreciate the part number but im looking to build a half h bridge since i already have the n channel mossfet place, i was wondering what else i need and how to connect it up besides another p channel ?
You'd normally use all n-channel and a high-low MOSFET driver.
(Hint: a high-low driver with automatic deadtime generation is a wise choice - otherwise
you'll probably hit shoot-through condition at some point and blow up your MOSFETs).
Its much easier to use the BTS7960 or similar and not have to design from scratch and make
the mistakes that everyone makes first time.
Hi Mark,
Well there are two reasons i would actually rather build it than buy it, first i am very new to electronics and to ardunio, and i tend to learn much faster whenever i do things myself instead of buy something that works. The second is where i live, though i have access to bits of electronics like fet's, that module here would cost about 100$ with delivery and customs which is way to expensive for me.
Could you please elaborate a little more what a high low driver is?
the dead time is prevent an open open state?
using something like a micro switch motor braking is so easy without an arduino, i don't fully understand why there aren't any schematics to build something very simple with only forward, off, brake.
Thanks,
So basically for 1 channel forward, stop, off it would seem all i need is something like IRS2001
2 n channel mosfets 2-3 capacitors and some resistors?
Edit - I added a schematic i found for the IRS2001
i imagine Vcc is the 12v, HIN, LIN the pwm 5v signals from the arduino, COM is the 5v + 12v grounds
what i can't understand though is what is Vb that it only connected through a diode to Vs which is the 12v positive output?
Also seems to me that
HI 0 LOW 0 engine doesn't spin only its positive is connected
HI 1 LOW 0 engine doesn't spin positive connected to ground, engine negative is floating (doesn't seem like a brake)
Hi 0 LOW 1 engine spinning
Hi 1 LOW 1 - things melt.
Did i understand correctly? if so i don't get why go to all this trouble if you only get engine forward and no brake even/
No that's wrong. One terminal of the motor to the mid-point of the half-bridge, the other to ground.
Lin Hin results
0 0 free wheel
1 0 brake
0 1 turn
1 1 MOSFETs explode immediately (not a joke, this is what happens!)
You need to PWM between brake and turn, but with dead-time between - the IRS2001 is
basically much harder to drive than a driver that automatically handles dead-time.
Note that to drive Hin/Lin in antiphase involves either knowledge of programming the ATmega
timer modules, or an external inverter.
I'd suggest ut FAN7380 which is 1/3rd of a FAN7388 basically, does the deadtime. There are
even drivers that have the inverter builtin so take a single input (and enable too).
Thank you mark (i always wish i could just give you 100 karma and get it over with )
I will look into a FAN7380.
MarkT:
Note that to drive Hin/Lin in antiphase involves either knowledge of programming the ATmega
timer modules, or an external inverter.
I have no idea what you said here, do you mean aligning the signals is such a way that only one of the terminals is open at a time, for quick switches between modes?
unless i missed something simple use such as just pwming the high for a couple of seconds, stopping and then pwming the low to brake the engine sound simple enough
I read the schematic wrong. So from what you said i assume the Vcc is 5v input and only the source of the HI mossfet is connected to the higher voltage?
So,
it would seem Fairchild stuff isn't sold in this country, i do have access though to these parts only none of them seem to do the job (the IR ones don't have any dead time function, and the ST ones have me confused because they don't seem to have pwm input channels)
STMICROELECTRONICS:
L6384D
L6384
INTERNATIONAL RECTIFIER:
IR2110PBF
IR2110STRPBF
IR2112-1PBF
IR2112PBF
IR2112SPBF
IR2113PBF
IR2113STRPBF
IR2153DPBF
I suggest you look at the datasheets to find out what each part does - I've quoted the devices
I've used before.
You can do as you suggest and do high-side PWM for running and low-side PWM separately for
braking. The only down side to that is less definite speed regulation whilst running.
