About the All-Electric ProDrive System

The environmental and economic value of Proterra’s ProDrive systems comes from its battery-electric design using our patented TerraVolt™ Energy Storage System. The battery dominant design eliminates the APU and therefore the expense associated with liquid fuel. The drive system emits no harmful emissions and recaptures greater than 90% of the energy generated during braking events.

Proterra’s ProDrive system is electrically driven with an optional on-board range extension generator set.  In an optional range extension version of the drive system, fuel (i.e., diesel, gasoline, etc.) powers an APU which turns an electrical generator to convert mechanical energy to electricity to charge the TerraVolt™ Energy Storage System.  TerraVolt™ then supplies energy to the traction motor, which drives the wheels of the vehicle. Because of the TerraVolt™ System’s ability to absorb as much energy as is available to it, the generator only runs when the vehicle control system turns it on to fast charge the energy storage system to the intended state of charge.

Proterra has developed an advanced vehicle control system to effectively manage the energy supply and demands of the vehicle.  In conventional drive systems and today’s hybrid vehicles, the power train controller only monitors functions to propel the vehicle (engine/transmission) leaving all other vehicle components to operate independently, energized by the engine.  Also, the typical control methodologies for these drive train components are reactive in nature, waiting for driver performance demands, then providing energy accordingly. 

Proterra’s control system continuously monitors all vehicle conditions and adapts each subcomponent/subsystem to maximize energy efficiency in conjunction with the entire vehicle system.  Since non-propulsion or “hotel load” demands such as heating and air conditioning can consume 50% of the overall vehicle’s energy needs, adapting the controls architecture to the entire vehicle’s energy requirements has significant upside for the overall vehicle energy efficiency. 

The controller also uses advanced GPS controls and adaptive control logic to predict future energy needs of the vehicle during operation.  In fixed route systems such as with transit buses and other urban fleet vehicles, once the vehicle has completed the intended drive cycle, the control software will adapt the controls as necessary to maximize efficiency and reduce emissions and noise for each subsequent repetitive cycle.

Proterra’s adaptive control system actively increases the energy efficiency in propulsion energy consumption, regenerative energy recapture as well as the accessory loads.