High-voltage power distribution enhances platform modernization

Story

January 04, 2010

John Wemekamp

Curtiss-Wright

The new generation of ground-based vehicles has moved away from the traditional 28 VDC power generation and distribution systems to high-voltage systems of typically 610 VDC, achieving great savings in space, weight, cost, and efficiency. Although easier to implement on new vehicle designs, high-voltage technology and many of its component parts can also be introduced into existing vehicles to great effect ? without the whole scale and potentially disruptive replacement of every 28 VDC powered electromechanical or electronic subsystem. Modernization programs aim to improve the warfighter?s operational effectiveness and survivability.

The new generation of ground-based vehicles has moved away from the traditional 28 VDC power generation and distribution systems to high-voltage systems of typically 610 VDC, achieving great savings in space, weight, cost, and efficiency. Although easier to implement on new vehicle designs, high-voltage technology and many of its component parts can also be introduced into existing vehicles to great effect – without the whole scale and potentially disruptive replacement of every 28 VDC powered electromechanical or electronic subsystem. Modernization programs aim to improve the warfighter’s operational effectiveness and survivability.

The continued presence of North Atlantic Treaty Organization (NATO) partners in areas of conflict has, for many nations, shifted combat doctrine and drained budgetary resources away from new large-scale ground vehicle procurement programs. Instead, life extension and modernization of existing fleets of armored vehicles is proposed – providing enhanced crew survivability – to add more firepower, increase situational awareness by introducing more Network Enabled Capability (NEC), and reduce maintenance and life-cycle costs. The recent rounds of rationalization, typified by the manned ground vehicle elements of Future Combat Systems (FCS), will result in the migration of new technologies into a series of phased modernization and update cycles for the current armored vehicle fleets to meet these objectives.

Mixed high- and low-voltage power systems

Significant weight, space, and efficiency gains will be achieved even by the partial adoption of new high-voltage power systems. Much of the new electrical technology is high-voltage based, whether power generation, distribution, all forms of motion control, driver control, or environmental controls. Modernization initiatives to infuse this technology into older vehicle types will result in two scenarios:

Change out of the power-generation system to the new high-voltage standard plus the introduction of some new high-voltage subsystems along with the retention of legacy 28 VDC subsystems.
Continue to generate power at 28 VDC but introduce some new technology subsystems requiring high voltage.

Both scenarios will utilize new power conversion technology between high voltage and 28 VDC or vice versa plus the inclusion of side-by-side distribution and switching systems.

Where and how this power conversion takes place will have a vital impact on a vehicle’s weight and space available for other equipment. A large armored vehicle such as a Main Battle Tank (MBT) might require 100+ kW power generation capability. At 28 VDC, this equates to 3,500 A to be distributed around the vehicle, requiring heavy cables and massive switchgear. Obviously, using a higher voltage reduces the current, allowing smaller, lighter cabling and switchgear. But crew safety also becomes a consideration, requiring additional physical protection of cables and connectors as well as the inclusion of ground fault detection circuit breakers.

Motion control

Motion control is one of the greatest consumers of power in an armored vehicle. Its applications range from the operation of hatches, fans, and pumps, to the environmental control of workspaces and electronic equipment, to a complete turret assembly. By providing a multi-axis stabilized platform for weapon, sensor, and crew systems, a typical turret system can require tens of kW per axis to control. The new generation of smart Servo Motor Controllers (SMCs) offers more opportunities for reducing weight and space. By providing high-power, three-phase synchronous output to the motor, an SMC can be directed to perform complex, preprogrammed movements by commands received via dual-redundant control buses such as CANbus or Ethernet.

Using solid-state switching and microprocessor technology, these SMCs offer increased reliability plus an inherent capability for sharing diagnostic and future prognostic results with other vetronics subsystems. Curtiss-Wright Controls Electronic Systems has played a major role in the development of equipment and installation technology for high-voltage ground vehicle power distribution, in addition to switching and motion control systems. Illustrating this breadth of expertise is a family of rugged, high-efficiency SMCs, packaged as Line Replaceable Units (LRUs) for vetronics applications, shown in Figure 1. Such an SMC can deliver two axis controls at up to 23 kW per axis in a package weighing only 22 lbs.

Figure 1: Curtiss-Wright Controls Electronic Systems family of rugged, high-efficiency SMCs, packaged as LRUs for vetronics applications.

Inserting high-voltage power technology into existing vehicle fleets will undoubtedly create significant savings in weight, space, and efficiency. However, careful trade-offs will be needed to ensure the optimum savings and benefits, particularly as phased introductions of new technologies into each vehicle type are proposed. This will require a deep understanding of each vehicle’s power infrastructure, its EMI characteristics, future upgrade plans, and crew safety requirements to create each optimal solution set.

To learn more, e-mail John at [email protected].