Battery Power - Blue Bird TC/2000 Owner's Manual

determines a Pulse Width Modulation (PWM) profile for the high power transistors. The PWM profile facili-
tates the microsecond switching capability that allows a smooth current flow from the Battery Pack through
the Power Distribution Unit, to the Motor Controller which produces variable frequency 3-phase alternating
current which drives the AC induction Motor. The Motor converts the electrical energy received from the
Motor Controller to mechanical energy, transmits it to the Speed Reducer which turns the differential on the
rear axle. In order to maintain a continuously smooth vehicle operation, the Motor Controller requires, and
receives, constant shaft-speed feedback from the Motor. The Power Distribution Unit also provides 12 volt
and 336 volt power for vehicle accessories. A rear mounted oil cooler is used to cool aircraft turbine oil that
flows through the Motor Controller, the Motor, and the Speed Reducer.
Chassis
Controller
Brake &
Accelerator
Battery
Pack
Traction
Battery
Pack

BATTERY POWER

The electric vehicle is operated solely by electric power. The power is provided by batteries as follows.
Traction Batteries
The battery packs provided to operate the electric school bus are herein identified as Traction Batteries.
Each individual 12 volt battery is an EVolyte 12-EVB-1180 battery. These batteries are absorbed electrolytes
which eliminates the possibility of leaking of fluids or the requirement to add water at any time. The electric
vehicle is powered by one-hundred-and-twelve (112), 12 volt valve regulated lead acid batteries. Each valve
regulated lead acid battery weighs approximately 66 pounds. Individual battery packs of twenty-eight (28)
batteries are connected in series and are located in the luggage compartments on each side of the vehicle.
Four of these battery packs are connected together in parallel. Failure in as many as 3 of the 4 battery packs
will degrade the driving range and speed of the bus but will not render the vehicle undriveable in most
instances or reduce its low speed torque (gradeability).
Speed, Position,
Control Commands
Status
Power
Motor
Distribution
Controller
Unit
DC / DC
Converter
DC / DC
Converter
Pump Inverter
2 hp
Pump Inverter
5 hp
Direction
Oil
Drive
Motor
Current
12 Volts
to Vehicle
12 Volts
to Radiator Fan
Motor Pump 2 hp
97
Fans (4)
Air
Oil
Radiator
Filter
Torque
Speed
Reducer
Steering &
Brake Hydraulics