This is my first attempt at a motor controller, it is essentially a mash-up of Shane's 3ph & FF designs. It borrows the gate drive circuitry from 3ph, and the inverter layout and RC filtering on the sensor inputs from the FF. The version pictured used an 18F1230 development board, which has since been updated to a dsPIC version. It was designed to control the hub motor.
Type: 3-Phase PMSM (sensored sine-wave commutation)
Power: 48V / 20A
Power Devices: IRLS4030
Gate Drive: HCPL-3120
Microcontroller: 18F1230, dsPIC33FJ12MC201
002EK001 (in progress):
This motor controller is designed to be a single-sided board for easy access and testing. It borrows some thermal techniques I've noticed working with LED driver boards.
Type: 3-Phase PMSM
Power: 48V / 20A
Power Devices: FDBL0150N80
Gate Drive: TI DRV8301
Microcontroller: dsPIC33FJ32MC204
Controller Design
MOSFETS:
Choosing the MOSFETs for this controller was pretty straightforward (and non-scientific). I searched digikey for FETs over 380W (the power rating used on e3PH), then looked at the various packages offered. I wanted to use something other than D2Pak, and found the Fairchild ones in an 8-PowerSFN package. The initial power rating was suitable at 429W and the Rdson of 1.4mΩ seemed low. I derated the FET for 100C ambient (typical for a motor controller) and then calculated the power dissipation and temperature rise which were all within parameter.
Bus Capacitors:
The bus capacitors provide instantaneous current to the inverter and shield the rest of the system from high-frequency switching transients. From what I can gather, the general strategy is that more is better with the only downside being increased size and cost. Any equivalent series resistance (ESR) will dissipate energy, so this should be minimized to increase efficiency, though I have read that sometimes ESR is good at decaying oscillations that would otherwise ring. Based on your desired acceptable voltage ripple (from inductance in the battery cables) you can calculate bus capacitance, which Shane outlines in his thesis.
Power Supplies:
The DRV8301 has a built-in TPS54160 step-down DC/DC switching regulator.
Current Measurement/ Signal Filtering:
The DRV8301 has two built-in current shunt amplifiers which will be used for measuring Phase A & B, an external OPA2374 will be used for measuring Phase C.
Power/ Signal Isolation:
?
Layout:
Getting rid of the heat is clearly an issue and 6 layers of 2oz copper with inches+ of through-hole vias should do the trick.
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