Schematic released!

A project log for Axiom: 100+kW Motor Controller

High Power, High Performance 400V 300A 100+kW Motor Controller fully compatible with VESCĀ®

Marcos ChaparroMarcos Chaparro 08/22/2019 at 03:180 Comments

It took us long enough, but we have finally converged to a releasable schematic!

Take a look for yourself:

I really don't remember seeing a schematic this complete, clear, complex, and public! Most of the team worked at aerospace and military organizations, so we know a thing or two about these documents and that experience was put into practice here. It is released under a Creative Commons BY-SA license.

Take for example a simple component like any of these capacitors.

Is the capacitance important? Of course! Is the rated voltage important? You bet!

A wrong capacitance value can be harmless, or detune a timing or filtering circuit. But using a 6.3Vdc capacitor on a 15Vdc rail will have dire consequences, hence the need to be verbose when drawing the schematic and be clear about the used ratings. You don't see this often in public schematics.

Resistors power rating present us a similar case. Take for example the CANbus termination resistor:

Can it withstand a continuous bus failure? If we are clear about the power ratings we can see that the termination resistor pair can take 500mW.

5V on a 120 Ohm resistor gives 208mW, so it should be alright. The DC Link discharge circuit needs to pass this continuous bleed check, with some extra safety consideration regarding discharge time.

Then you have the more common practice of drawing the signal flow from left to right, for example in the signal conditioning circuit (there is one of these blocks for each phase):

Many people asked about the FPGA implementation, and its a straightforward one.

It is configured over SPI, pwm signals are level shifted from 3.3V to 5V for better integrity under high EMI. The SPI bus can be used for high speed general purpose communication between MCU and FPGA. The ice40up5k eval board had some errors that were fixed in Axiom schematic regarding PLL supply filtering and power supply sequencing.

So there you have, an earth-shattering, high quality 34 page document meant to bring electric vehicles and high power motor control closer to everyone!

PS: Schematic was first released days ago to our newsletter subscribers. Subscribe now to hear first about Axiom news!