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.

What is claimed is: 
     
         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 . A method as recited in  claim 1  wherein the transition profile is a cubic function profile. 
     
     
         3 . A method as recited in  claim 1  wherein the second output level is zero torque. 
     
     
         4 . A method as recited in  claim 3  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. 
     
     
         5 . 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. 
     
     
         6 . 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. 
     
     
         7 . A method as recited in  claim 1  wherein the transition profiles are transition torque profiles. 
     
     
         8 . A method as recited in  claim 1  wherein the transition profiles are transition current profiles. 
     
     
         9 . A method as recited in  claim 1  wherein the transition profile is a quintic function transition profile. 
     
     
         10 . A method as recited in  claim 1  wherein the transition profile is a seventh order or higher transition profile. 
     
     
         11 . 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.   
     
     
         12 . An electric machine controller as recited in  claim 11  wherein the torque transition profile is a cubic or higher order function transition profile. 
     
     
         13 . An electric machine controller as recited in  claim 11  wherein the torque transition profile is a cubic function transition profile. 
     
     
         14 . An electric machine controller as recited in  claim 11  wherein the torque transition profile is a quintic function transition profile. 
     
     
         15 . An electric machine controller as recited in  claim 11  wherein the torque transition profile is a seventh order function transition profile. 
     
     
         16 . An electric machine controller as recited in  claim 11  wherein the second output level is zero torque. 
     
     
         17 . An electric machine controller as recited in  claim 16  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. 
     
     
         18 . 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.   
     
     
         19 . An electric machine controller as recited in  claim 18  wherein the current transition profile is a cubic or higher order function transition profile. 
     
     
         20 . An electric machine controller as recited in  claim 18  wherein the current transition profile is a cubic function transition profile. 
     
     
         21 . An electric machine controller as recited in  claim 18  wherein the current transition profile is a quintic function transition profile. 
     
     
         22 . An electric machine controller as recited in  claim 18  wherein the current transition profile is a seventh order function transition profile. 
     
     
         23 . An electric machine controller as recited in  claim 18  wherein the second output level is zero torque. 
     
     
         24 . An electric machine controller as recited in  claim 23  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. 
     
     
         25 . 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 least an initial portion of selected transitions from the second output level to the first output level using a cubic or higher order transition profile.   
     
     
         26 . A method as recited in  claim 25  wherein the transition profile is a quintic function profile. 
     
     
         27 . A method as recited in  claim 25  wherein the transition profile is a cubic function profile. 
     
     
         28 . A method as recited in  claim 25  wherein the transition profile is a profile having an order that is higher than quintic. 
     
     
         29 . A method as recited in  claim 25  wherein the second output level is zero torque. 
     
     
         30 . A method as recited in  claim 29  wherein the electric machine is controlled by an inverter and in at least some 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. 
     
     
         31 . A method as recited in  claim 25  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. 
     
     
         32 . A method as recited in  claim 25  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. 
     
     
         33 . A method as recited in  claim 25  further comprising additionally controlling at least one of (a) a final portion of selected transitions from the first output level to the second output level, (b) a final portion of selected transitions from the second output level to the first output level, or (c) an initial portion of selected transitions from the first output to the second output level using a cubic or higher order transition profile. 
     
     
         34 . A method as recited in  claim 25  wherein the transition profiles are transition torque profiles. 
     
     
         35 . A method as recited in  claim 25  wherein the transition profiles are transition current profiles. 
     
     
         36 . An electric machine controller arranged to direct operation of a power converter that controls an electric machine, the electric machine controller comprising:
 a pulsing decision module that determines when pulsed operation of the electric machine is desirable and when continuous operation of the electric machine is desirable to deliver a desired average output; and   a pulse controller that directs the pulsed operation of the electric machine when the pulsing decision module determines that the pulsed operation of the electric machine is desirable, wherein the pulsed operation causes the electric machine to alternate between a first output level that is greater than the desired average output and a second output level that is less than the desired average output, the pulse controller including a transition profile generator that controls at least initial portions of selected transitions from the second output level to the first output level using a cubic or higher order transition profile.   
     
     
         37 . An electric machine controller as recited in  claim 36  wherein the transition profile generator controls the selected transitions from the second output level to the first output level using a quintic or higher transition profile. 
     
     
         38 . An electric machine controller as recited in  claim 36  wherein the transition profile generator controls the selected transitions from the first output level to the second output level using a cubic transition profile. 
     
     
         39 . An electric machine controller as recited in  claim 36  wherein the second output level is zero torque and during pulsing in at least some operating states, the power converter is turned off during at least a portion of the time that the electric machine is caused to output zero torque. 
     
     
         40 . An electric machine controller as recited in  claim 36  wherein the transition profiles are transition torque profiles. 
     
     
         41 . An electric machine controller as recited in  claim 36  wherein the transition profiles are transition current profiles. 
     
     
         42 . An electric machine including an electric machine controller as recited in  claim 36 . 
     
     
         43 . An electric machine as recited in  claim 42  wherein the electric machine is a motor, a generator or a motor/generator. 
     
     
         44 . 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 least one of (a) an initial portion of selected transitions from the second output level to the first output level, (b) a final portion of selected transitions from the first output level to the second output level, (c) a final portion of selected transitions from the second output level to the first output level, or (d) an initial portion of selected transitions from the first output to the second output level, using a cubic or higher order transition profile.