Wisconsin Alumni Research Foundation

Reducing DC-DC Converter Loss for More Efficient Cars
WARF: P130119US01

Inventors: Robert Lorenz, Chi-Ming Wang, Masaki Wasekura

The Wisconsin Alumni Research Foundation (WARF) is seeking commercial partners interested in developing loss optimization control for the DC-to-DC converters found in vehicle power systems.
DC-DC converters are used in a variety of devices to raise or lower voltage. They are used in the power systems of hybrid and electric vehicles to boost the battery’s output voltage. In these systems, an upper controller continually samples and determines the motor’s target output in response to speed and the position of the accelerator pedal. For a motor outputting several tens of kilowatts, sampling time (Ta) is typically every 0.1 seconds.

Since efficiency is particularly important in hybrid and electric vehicles, the efficiency of the DC converter is critical too. Some amount of energy loss always takes place. Minimizing loss would mean a car could be driven longer on a tank of gas or battery charge.
The Invention
UW–Madison researchers have developed a technique for reducing loss in DC-DC converters by estimating and selecting the best flux linkage trajectory to meet target output. This is accomplished rapidly, within the time it takes to sample the system at large (Ta).

The loss associated with each of the possible trajectories can be stored in the converter controller or may be calculated in real time. The trajectory with the least loss is selected and implemented using a deadbeat control law, which can accurately achieve the loss minimizing flux linkage trajectory.
  • Improving DC-DC converters in vehicles
Key Benefits
  • Makes cars more efficient
  • Control system update is simple.
  • Inexpensive and easy to implement
  • No hardware additions or extensive redesigns
Stage of Development
In experimental setups, loss differences of 4.4 percent (200-250 volts) and 2.8 percent (400-450 volts) were observed. Even a 1 percent difference is considered a significant improvement for automakers.
For current licensing status, please contact Michael Carey at [javascript protected email address] or 608-960-9867