The VCU (Vehicle Control Unit)


Here’s the thing.  In the early ’80s, it dawned on car builders that they could use these newfangled microprocessor things to help maintain and control engine performance, using sort of a mix of analog sensors and electronic processors.  As the systems became more capable, the analog sensor part got replaced by full-electronic systems.  You can read more about this on the Wikipedia page for Engine Control Units.

Fast forward to the Energica.  They talk about their VCU – or Vehicle Control Unit in their brochure, here.  Having experienced it, even without the ABS braking integrated, I can attest to the fact that it works really really well.  It’s primarily a motor control, but integrates the regen braking with the throttle response, and also now the ABS system.  In the words of Energica’s CTO, (AKA “Giampi”): “A big improvement we have done from the prototypes and the production bike is the torque control when regen braking is active, it is a sort of anti locking system for the rear wheel when releasing the throttle in conditions of low traction.”

Now.  The question is, in an electric vehicle application, what can we do with a VCU, and how might it be different than working with an ICE ECU?  Second question first, again from Giampi:

“A VCU for an electric vehicle is completely different from the ICE counterpart since it manages completely the vehicle. Our VCU handles not only the “services” such as water pump, horn, lights etc, but manages also the ride by wire, riding modes, regen modes, all the safety and diagnostics, datalogging etc. etc. 

Having to control a torque value, the control of an electric vehicle is much more accurate than an ICE motorcycle, where you need to work on advance and retard, injection, opening of throttle and the reaction of the combustion engine must be predicted. On an EV when you “ask” for an exact value, the controller and motor give that exact value. 

We have integrated the VCU together with the ECU (they are normally 2 different entities inside an ICE vehicle). 

As far as control of the exact values it is far superior due to “talking the same language of the motor”, while in the other areas it is as good as the ICE VCUs.”

As far as the first question goes, it’d make sense to look at what Tesla’s doing for an idea of what’s possible.  Here’s a link to the discussion of the Tesla Roadster “PEM” (Power Electronics Module), and a bit of an idea:

In drive mode, the Power Electronics Module responds to information from the accelerator pedal, motor speed sensor, ABS speed sensors, and other powertrain sensors.  The Power Electronics Module determines requested torque from the pedal position and monitors the ABS speed sensors to detect if tires are slipping. Based on sensor feedback, it produces torque by converting the DC voltage stored in the battery to the appropriate AC voltage at the motor terminals. As the driver steps on the accelerator pedal, the Power Electronics Module begins to control increasing motor current and voltage to produce the torque required to accelerate from 0 to 60 mph in 3.7 seconds.  

In charge mode, the Power Electronics Module converts AC voltage from the grid at between 90V and 265V, into DC voltages between 250V and 425V.   The wide allowable input AC voltage range enables the car to charge from nearly any outlet in the world. Input frequency can be either 50Hz or 60Hz, again for global compatibility. The Vehicle Management System (VMS) calculates the battery’s state of charge and sends charge requests to the PEM which then outputs power to the battery based on the requested charge current.

So that’s what it can do, and I’d guess it can do more, if the system includes adaptive suspension and other rarified technology.  We should note, too, that the Energica VCU is a separate unit, not integrated with the controller system, but tied to that, as well as the ABS – so it’s a proprietary system that can be used in other applications to some degree.

…which begs the question, what does Zero and Brammo (Polaris) tout for VCU tech?  From their sites, Zero calls it a MBB or main battery board, which is actually the BMS (battery management system).  Brammo calls it the VCU, “The Vehicle Control Unit (VCU) monitors all aspects of the battery’s performance and maintains consistent balance, performance, and health of (the battery).”

So yeah, simply a BMS.  Energica is arguably the first company to integrate VCU thinking into their drivetrain, and I can say from personal experience, really well.  Where it goes from there – anti-dive suspension, ABS coupled with lean sensors for enhanced slip control, wheelie control?  I don’t really know whether to label this post “History”, or “Future”, but it’s pretty interesting.



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