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Electric vehicle with variable efficiency regenerative braking depending upon battery charge state

  • US 5,941,328 A
  • Filed: 03/20/1998
  • Issued: 08/24/1999
  • Est. Priority Date: 11/21/1997
  • Status: Expired due to Term
First Claim
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1. A method for operating an electric vehicle which includes a traction motor connected for driving at least one drive wheel of said vehicle, and a control system for converting motion of said vehicle into electrical energy during braking, and for varying the amount of electrical energy produced by the traction motor during braking by adjusting the efficiency of the traction motor said method comprising the steps of:

  • returning substantially all of the energy from said traction motor to said batteries during braking, at a maximum efficiency of said traction motor operated as a generator, when said batteries are at a first charge condition which is less than a full charge condition;

    adjusting the efficiency of said traction motor to a level intermediate said maximum efficiency and zero efficiency, for returning less than all of said energy from said traction motor to said batteries during braking when said batteries are at a charge level between said first charge condition and said full-charge condition; and

    adjusting the efficiency of said traction motor to a selected level of low efficiency, which is intermediate the zero efficiency and said intermediate level of efficiency when said batteries are at said first charge condition for returning a minimum amount of said energy from said traction motor to said batteries when said batteries are at said full-charge condition.

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