Electric machine comprising an alternating current electric motor and an inverter

Abstract

An electric machine may include: an alternating current electric motor comprising a first semi-winding and a second semi-winding; an inverter comprising a first inverter branch electrically connected to the first semi-winding and a second inverter branch electrically connected to the second semi-winding; and a control unit configured to provide a first control signal to the first inverter branch, so as to induce a first alternating current in the first semi-winding, and a second control signal to the second inverter branch, so as to induce a second alternating current in the second semi-winding. The first and second alternating currents may have a first frequency. The first and second control signals may have a second frequency that is less than the first frequency. The first and second control signals may be reciprocally out of phase by substantially 180° relative to the second frequency.

1 . An electric machine, comprising:
 an alternating current electric motor comprising a first semi-winding and a second semi-winding;   an inverter comprising a first inverter branch electrically connected to the first semi-winding and a second inverter branch electrically connected to the second semi-winding; and   a control unit configured to provide a first control signal to the first inverter branch, so as to induce a first alternating current in the first semi-winding, and a second control signal to the second inverter branch, so as to induce a second alternating current in the second semi-winding;   wherein the first alternating current and the second alternating current have a first frequency,   wherein the first control signal and the second control signal have a second frequency that is less than the first frequency, and   wherein the first control signal and the second control signal are reciprocally out of phase by substantially 180° relative to the second frequency.   
     
     
         2 . The electric machine of  claim 1 , wherein the alternating current electric motor is a three-phase electric motor, and
 wherein a sum of the first alternating current and the second alternating current is a phase of a three-phase current.   
     
     
         3 . The electric machine of  claim 1 , wherein the first semi-winding and the second semi-winding are electrically connected according to a “Y” configuration or a “Δ” configuration. 
     
     
         4 . The electric machine of  claim 1 , wherein the first semi-winding and the second semi-winding are arranged so as to behave as a primary winding and a secondary winding of a transformer. 
     
     
         5 . The electric machine of  claim 1 , wherein the first semi-winding and the second semi-winding have electric inductances having a same value. 
     
     
         6 . The electric machine of  claim 1 , wherein the inverter further comprises a number N≧1 of first inverter branches electrically connected to the first semi-winding and a same number N≧1 of second inverter branches electrically connected to the second semi-winding. 
     
     
         7 . The electric machine of  claim 1 , wherein each one of the first inverter branch and second inverter branch comprises:
 a first switch;   a second switch connected in series to the first switch;   a first diode connected in anti-parallel configuration with the first switch; and   a second diode connected in anti-parallel configuration with the second switch;   wherein the first switch and the second switch are connected to the control unit, and   wherein the first switch and the second switch are configured to switch between an open state and a closed state.   
     
     
         8 . The electric machine of  claim 1 , wherein the first control signal is configured to induce the first inverter branch to provide a first voltage across the first semi-winding,
 wherein the second control signal is configured to induce the second inverter branch to provide a second voltage across the second semi-winding,   wherein the first voltage and the second voltage have a same waveform, and   wherein the first voltage and the second voltage are reciprocally delayed in time by substantially 1/2f P .   
     
     
         9 . The electric machine of  claim 8 , wherein the waveform comprises a sequence of pulses with pulse frequency equal to the second frequency. 
     
     
         10 . A method for supplying an alternating current electric motor that comprises a first semi-winding and a second semi-winding using an inverter that comprises a first inverter branch electrically connected to the first semi-winding and a second inverter branch electrically connected to the second semi-winding, the method comprising:
 providing a first control signal to the first inverter branch so as to induce a first alternating current in the first semi-winding; and   providing a second control signal to the second inverter branch so as to induce a second alternating current in the second semi-winding;   wherein the first alternating current and the second alternating current have a first frequency,   wherein the first control signal and the second control signal have a second frequency that is less than the first frequency, and   wherein the first control signal and the second control signal are reciprocally out of phase by substantially 180° relative to the second frequency.   
     
     
         11 . The electric machine of  claim 1 , wherein the first semi-winding and the second semi-winding are electrically connected according to a “Y” configuration. 
     
     
         12 . The electric machine of  claim 1 , wherein the first semi-winding and the second semi-winding are electrically connected according to a “Δ” configuration. 
     
     
         13 . The electric machine of  claim 1 , wherein the alternating current electric motor is a three-phase electric motor. 
     
     
         14 . The electric machine of  claim 13 , wherein the first semi-winding and the second semi-winding are electrically connected according to a “Y” configuration. 
     
     
         15 . The electric machine of  claim 13 , wherein the first semi-winding and the second semi-winding are electrically connected according to a “Δ” configuration. 
     
     
         16 . The electric machine of  claim 1 , wherein the first semi-winding is arranged so as to behave as a primary winding of a transformer. 
     
     
         17 . The electric machine of  claim 1 , wherein the second semi-winding is arranged so as to behave as a secondary winding of a transformer. 
     
     
         18 . The electric machine of  claim 1 , wherein the inverter further comprises a plurality of first inverter branches electrically connected to the first semi-winding and a plurality of second inverter branches electrically connected to the second semi-winding. 
     
     
         19 . The electric machine of  claim 18 , wherein a number of the plurality of first inverter branches is equal to number of the plurality of second inverter branches. 
     
     
         20 . An electric machine, comprising:
 an alternating current electric motor comprising a first semi-winding and a second semi-winding;   an inverter comprising a first inverter branch electrically connected to the first semi-winding and a second inverter branch electrically connected to the second semi-winding; and   a control unit configured to provide a first control signal to the first inverter branch, so as to induce a first alternating current in the first semi-winding, and a second control signal to the second inverter branch, so as to induce a second alternating current in the second semi-winding;   wherein the first alternating current and the second alternating current have a first frequency,   wherein the first control signal and the second control signal have a second frequency that is less than the first frequency, and   wherein the first control signal and the second control signal are reciprocally out of phase by 180° relative to the second frequency.