Modular Propulsion System

Highlights

• Over 30 locomotive systems in daily operation
• Modular rack construction
• Automatic wheel-slip and wheel-slide control
• Automatic regenerative braking to near zero speed
• Rack is fully tested before shipping to customer
• Common power module for armature, field and brake choppers



• The A300631 Rectifier Module converts 480V, 60Hz AC power to DC power at a voltage of approximately 650V. The output of the rectifier module is smoothed by six A300636 parallel-connected capacitors. Line reactor, A300637, reduces the harmonic load on the 480V supply. The A300631 rectifier module consists of a half-controlled SCR / Diode bridge for the purpose of limiting the charging current drawn by the bus capacitors during power up
• The A300633, A300634 and A300635 Chopper Modules are power converters designed to operate over a DC bus voltage range of 500V to 800V. They are used as components of a power conversion system consisting of several modules sharing a common DC bus filter capacitor
• When the A300634 Armature Chopper Module is used to control the armature of a DC traction motor, it controls the armature current by applying pulses of the DC bus voltage directly to the armature at a frequency of 1kHz. The chopper can supply the armature with a very large amount of current at low speed while consuming a relatively small amount of current from the DC bus. The Armature Chopper Module also receives speed feedback from the axle that it is driving and continuously compares the measured axle speed with a reference input derived from a non-driven axle. For the purpose of controlling wheel-spin or wheel-slide, a speed regulator overrides the traction reference with a lower value if the axle speed deviates outside a small band of acceptable values.
• The Armature Chopper Module can also operate very effectively as a brake down to very low speeds. It achieves this by applying a voltage to the armature that is lower than its open-circuit voltage so that both current and power flow are reversed. This change occurs as a seamless transition when the polarity of the traction reference is reversed.li>
• Energy recovered from the traction motors during dynamic braking is returned to the DC bus. All of the energy returned to the bus must be dissipated without resulting in a large increase in voltage. The excess power is absorbed in dynamic brake resistors controlled by the A300635 Dynamic Brake Chopper. The Dynamic Brake Chopper normally operates independently by responding only to the increase in DC bus voltage that occurs when power absorbed by the Armature Chopper Modules is returned to the DC bus.li>

  Components used in this system

  Traction Drive:

  500HP DC Traction