Pulsed electric machine control

Abstract

A variety of methods, controllers and electric machine systems are described that facilitate pulsed control of electric machines to improve the energy efficiency of the electric machine when conditions warrant. Selected transitions between pulsing output levels are controlled to provide a cubic or higher order transition torque profile. In various implementations, cubic, quintic or higher order transition profiles are use. The use of such transition torque profiles can improve NVH characteristics of the electric machine while providing energy efficient pulse transitions.

1 . A method of controlling operation of an electric machine, the method comprising:
 directing pulsed operation of the electric machine to deliver a requested average output, wherein the pulsed operation causes the electric machine to alternate between a first output level that is greater than the requested average output and a second output level that is less than the requested average output; and   controlling at selected transitions between the output levels using a cubic or higher order transition profile.   
     
     
         2 . (canceled) 
     
     
         3 . A method as recited in  claim 1  wherein the transition profile is a cubic function profile. 
     
     
         4 . (canceled) 
     
     
         5 . A method as recited in  claim 1  wherein the second output level is zero torque. 
     
     
         6 . A method as recited in  claim 5  wherein the electric machine is controlled by an inverter and in selected operating states, the inverter is turned off during at least a portion of the time that the electric machine is caused to output zero torque. 
     
     
         7 . A method as recited in  claim 1  wherein the transitions between the output levels are controlled by controlling the torque generated by the electric machine using the cubic or higher order transition profile. 
     
     
         8 . A method as recited in  claim 1  wherein the transitions between the output levels are controlled by controlling current supplied to the electric machine using the cubic or higher order transition profile. 
     
     
         9 . (canceled) 
     
     
         10 . A method as recited in  claim 1  wherein the transition profiles are transition torque profiles. 
     
     
         11 . A method as recited in  claim 1  wherein the transition profiles are transition current profiles. 
     
     
         12 .- 20 . (canceled) 
     
     
         21 . An electric machine controller arranged to direct operation of a power converter that controls an electric machine, the electric machine controller comprising:
 a pulse controller that directs pulsed operation of the electric machine to deliver a requested average output, wherein the pulsed operation causes the electric machine to alternate between a first output level that is greater than the requested average output and a second output level that is less than the requested average output; and   wherein the pulse controller directs transitions from at least one of (i) the first output to the second output level; and (ii) the second output level to the first output level, using an S-shaped commanded torque transition profile.   
     
     
         22 . An electric machine controller as recited in  claim 21  wherein the torque transition profile is a cubic or higher order function transition profile. 
     
     
         23 . An electric machine controller as recited in  claim 21  wherein the torque transition profile is a cubic function transition profile. 
     
     
         24 . An electric machine controller as recited in  claim 21  wherein the torque transition profile is a quintic function transition profile. 
     
     
         25 . An electric machine controller as recited in  claim 21  wherein the torque transition profile is a seventh order function transition profile. 
     
     
         26 . An electric machine controller as recited in  claim 1  wherein the second output level is zero torque. 
     
     
         27 . An electric machine controller as recited in  claim 26  wherein the electric machine is controlled by an inverter and in selected operating states, the inverter is turned off during at least a portion of the time that the electric machine is caused to output zero torque. 
     
     
         28 . An electric machine controller arranged to direct operation of a power converter that controls an electric machine, the electric machine controller comprising:
 a pulse controller that directs pulsed operation of the electric machine to deliver a requested average output, wherein the pulsed operation causes the electric machine to alternate between a first output level that is greater than the requested average output and a second output level that is less than the requested average output; and   wherein the pulse controller directs transitions from at least one of (i) the first output to the second output level; and (ii) the second output level to the first output level, using an S-shaped commanded current transition profile.   
     
     
         29 . An electric machine controller as recited in  claim 28  wherein the current transition profile is a cubic or higher order function transition profile. 
     
     
         30 . An electric machine controller as recited in  claim 28  wherein the current transition profile is a cubic function transition profile. 
     
     
         31 . An electric machine controller as recited in  claim 28  wherein the current transition profile is a quintic function transition profile. 
     
     
         32 . An electric machine controller as recited in  claim 28  wherein the current transition profile is a seventh order function transition profile. 
     
     
         33 . An electric machine controller as recited in  claim 28  wherein the second output level is zero torque. 
     
     
         34 . An electric machine controller as recited in  claim 33  wherein the electric machine is controlled by an inverter and in selected operating states, the inverter is turned off during at least a portion of the time that the electric machine is caused to output zero torque. 
     
     
         35 . A method as recited in  claim 1  wherein the transition profile is a quintic function transition profile. 
     
     
         36 . A method as recited in  claim 1  wherein the transition profile is a seventh order or higher transition profile.