Very little performance data is available for chopper controlled dc series motors as used in battery powered electric vehicles. This report presents preformance data obtained through experimental testing of a 22.4-KW (30 hp) traction motor using two types of excitation: ripple-free dc from a motor-generator set for baseline data and pulse-width modulated (chopped) dc as suppled by a battery and chopper controller. For the same average values of input voltage and current, the power output was independent of the type of excitation. However, at the same speeds, the motor efficiency at low power output (corresponding to low duty cycle of the controller) was 5 to 10 percentage points less on chopped dc than on ripple-free dc. This apparent discrepancy illustrates tht for chopped dc waveforms, it is incorrect to calculate input power as the product of average voltage and current. The chopped dc locked-rotor torque was approximately 1 to 3% greater than the ripple-free dc locked-rotor torque for the same average values of current. (ERA citation 04;056873)

  • Corporate Authors:

    Department of the Navy

    The Pentagon
    Washington, DC  United States  20350

    Department of Energy

    1000 Independence Avenue, SW
    Washington, DC  United States  20585
  • Authors:
    • Schwab, J R
  • Publication Date: 1979-9

Media Info

  • Pagination: 27 p.

Subject/Index Terms

Filing Info

  • Accession Number: 00317727
  • Record Type: Publication
  • Source Agency: National Technical Information Service
  • Report/Paper Numbers: NASA-TM-79252
  • Contract Numbers: EC-77-A-31-1044
  • Files: TRIS
  • Created Date: Jan 19 1981 12:00AM