Hi everyone,
I am designing my own H-bridge to make my own riding scooter. I am using 3x12V 12Ah batteries and the motor is going to be a 1000w 36V motor. I am using an additional 12V battery for controls. All the grounds will be tied together. I have the basic design setup but I have a few questions.
I attached my schematic for the LSD and the HSD. Ignore the names, I just wanted to present a schematic. Those are not my actual part numbers or values.
My HSD schematic basically takes a 5V signal from the microcontroller to drive a NMOS. The NMOS is hooked up to a 12V supply that is used to drive a PMOS. The PMOS is hooked up to the 36V battery load to turn on the motor.
The LSD schematic takes a 12V signal and uses a boost circuit to convert it to 60V (used Ladyada boost calculator). The 60V is used to drive the 36V load of the motor.
My question is basically a review of basics of transistors.
HSD schematic:
Will the 5V and 12V signal combine for a 17V signal or will it be a negative -7V signal?
Can the negative voltage on the gate turn on the NMOS?
Will the 12V to 36V difference result in a -24V on the gate?
Will this turn on the PMOS?
Any concerns?
LSD schematic:
Are there any problems with using a boost circuit to activate a NMOS?
My understanding is the gate voltage must be higher then the source voltage (hints the 60V) is this correct in this application?
Other notes/questions:
I realize that there will be some voltage drops because on the on resistance of the transistors and the motor.
Power dissipation of a transistor:
I read that the power dissipated by the transistor can be calculated with the on resistance and the current, is this true?
My application should draw a peak of 27A so that gives me a maximum power rating of (22mOhm)*27^2, is that correct?
Sorry this is very scattered brained but I am just analyzing thing over and over again and have some uncertainty. Anyone that can give me some insight would be much appreciated.
I am designing my own H-bridge to make my own riding scooter. I am using 3x12V 12Ah batteries and the motor is going to be a 1000w 36V motor. I am using an additional 12V battery for controls. All the grounds will be tied together. I have the basic design setup but I have a few questions.
I attached my schematic for the LSD and the HSD. Ignore the names, I just wanted to present a schematic. Those are not my actual part numbers or values.
My HSD schematic basically takes a 5V signal from the microcontroller to drive a NMOS. The NMOS is hooked up to a 12V supply that is used to drive a PMOS. The PMOS is hooked up to the 36V battery load to turn on the motor.
The LSD schematic takes a 12V signal and uses a boost circuit to convert it to 60V (used Ladyada boost calculator). The 60V is used to drive the 36V load of the motor.
My question is basically a review of basics of transistors.
HSD schematic:
Will the 5V and 12V signal combine for a 17V signal or will it be a negative -7V signal?
Can the negative voltage on the gate turn on the NMOS?
Will the 12V to 36V difference result in a -24V on the gate?
Will this turn on the PMOS?
Any concerns?
LSD schematic:
Are there any problems with using a boost circuit to activate a NMOS?
My understanding is the gate voltage must be higher then the source voltage (hints the 60V) is this correct in this application?
Other notes/questions:
I realize that there will be some voltage drops because on the on resistance of the transistors and the motor.
Power dissipation of a transistor:
I read that the power dissipated by the transistor can be calculated with the on resistance and the current, is this true?
My application should draw a peak of 27A so that gives me a maximum power rating of (22mOhm)*27^2, is that correct?
Sorry this is very scattered brained but I am just analyzing thing over and over again and have some uncertainty. Anyone that can give me some insight would be much appreciated.
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