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An AC-AC power converter supplies AC power to an AC motor having a plurality of motor windings and a case connected to a ground. The AC-AC power converter architecture includes an asymmetric phase shift autotransformer/rectifier unit (ATRU) that converts an AC input to a DC output, wherein the asymm

An AC-AC power converter supplies AC power to an AC motor having a plurality of motor windings and a case connected to a ground. The AC-AC power converter architecture includes an asymmetric phase shift autotransformer/rectifier unit (ATRU) that converts an AC input to a DC output, wherein the asymmetric phase shift ATRU generates a common-mode AC voltage across the asymmetric phase shift ATRU. The common mode voltage is diverted to ground through motor case parasitic capacitance via a common-mode voltage pull-down circuit connected between each phase of the ATRU AC input and the ground.

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1. An AC-AC power converter architecture for supplying AC power to an AC motor having a plurality of motor windings and a case connected to a ground terminal, the AC-AC power converter architecture comprising: an asymmetric phase shift autotransformer/rectifier unit (ATRU) that converts an AC input

1. An AC-AC power converter architecture for supplying AC power to an AC motor having a plurality of motor windings and a case connected to a ground terminal, the AC-AC power converter architecture comprising: an asymmetric phase shift autotransformer/rectifier unit (ATRU) that converts an AC input to a DC output, wherein the asymmetric ATRU generates a common-mode AC voltage across the asymmetric ATRU, and wherein the asymmetric ATRU includes an asymmetric autotransformer;a DC-AC converter that converts the DC output to an AC output for supply to the AC motor; anda front-end filter connected to an input of the asymmetric ATRU to filter harmonics associated with the ATRU, wherein the front-end filter includes a common-mode pull-down voltage circuit connected between each phase of the AC input and the ground terminal connected to the case;wherein the asymmetric autotransformer provides six outputs that include a first group of AC outputs phase-shifted to lead the AC input voltages, and a second group of AC outputs phase-shifted to lag the AC input voltages. 2. The AC-AC power converter architecture of claim 1, wherein the common-mode voltage pull-down circuit utilizes a parasitic capacitance created between the plurality of motor windings and the case to dissipate the common-mode voltage generated by the asymmetric ATRU. 3. The AC-AC power converter architecture of claim 2, wherein the common-mode voltage pull-down circuit includes first, second and third capacitors connected between respective phases of the AC input and the ground terminal, and fourth, fifth, sixth capacitors connected between respective phases of the AC input and a series-connected resistor connected to the ground terminal. 4. The AC-AC power converter architecture of claim 1, wherein the first group of AC outputs are phase-shifted to lead the AC input voltages by 20°, and the second group of AC outputs are phase-shifted to lag the AC input voltages by 20°. 5. The AC-AC power converter architecture of claim 4, wherein the ATRU further includes: a first bridge rectifier for converting the filtered AC input provided by the front-end filter to a positive DC output and a negative DC output;a second bridge rectifier for converting the first group of AC outputs to a positive DC output and a negative DC output; anda third bridge rectifier for converting the second group of AC outputs to a positive and negative DC output. 6. The AC-AC power converter architecture of claim 4, wherein the ATRU includes: input terminals In1, In4, and In7 connected to the three-phase AC input voltage;a first plurality of coils A0, A0′, A1, A1′, and A2 wound on a first leg of the asymmetric autotransformer, connected to the input terminal In1 and output terminals Out6 and Out8, each coil of the first plurality of coils defined by a number of winding turns associated with the coil;a second plurality of coils B0, B0′, B1, B1′, and B2 wound on a second leg of the asymmetric autotransformer, connected to the input terminal In4 and output terminals Out2 and Out9, each coil of the second plurality of coils defined by a number of winding turns associated with the coil; anda third plurality of coils C0, C0′, C1, C1′, and C2 wound on a third leg of the asymmetric autotransformer, connected to the input terminal In7 and output terminals Out3 and Out5, each coil of the third plurality of coils defined by a number of winding turns associated with the coil; anda plurality of internal terminals T1-T6 for interconnecting the first, second and third plurality of coils in a desired configuration. 7. The AC-AC power converter architecture of claim 6, wherein the AC output provided at output terminal Out6 leads the AC output provided at the input terminal In7 by 20° and the AC output provided at output terminal Out8 lags the AC output provided at the input terminal In7 by 20°, the AC output provided at output terminal Out9 leads the AC output provided at the input terminal In1 by 20° and the AC output provided at output terminal Out2 lags the AC output provided at the input terminal In1 by 20°, and the AC output provided at output terminal Out3 leads the AC output provided at the input terminal In4 by 20° and the AC output provided at output terminal Out5 lags the AC output provided at the input terminal In4 by 20°. 8. The AC-AC power converter architecture of claim 7, wherein the coils A0, A2, and A0′ are connected in series between input terminals In1 and In4 via internal terminals T2 and T3, coils B0, B2, and B0′ are connected in series between input terminals In4 and In7 via internal terminals T4 and T5, and coils C0, C2, and C0′ are connected in series between input terminals In7 and In1 via internal terminals T6 and T1, wherein coil A1 is connected between internal terminal T5 and output terminal Out6, coil A1′ is connected between internal terminal T6 and output terminal Out8, coil B1 is connected between internal terminal T1 and output terminal Out9, coil B1′ is connected between internal terminal T2 and output terminal Out2, coil C1 is connected between internal terminal T3 and output terminal Out3, coil C1′ is connected between internal terminal T4 and output terminal Out5. 9. The AC-AC power converter architecture of claim 8, wherein the length of each of the first, second, and third plurality of coils is provided by the following table: CoilNumber of turnsA0, B0, C0n0A0′, B0′, C0′n0A1, B1, C1,n1=[3*sin⁡(π9)4*sin⁡(π18)2-12]*n⁢⁢0A1′, B1′, C1′n1=[3*sin⁡(π9)4*sin⁡(π18)2-12]*n⁢⁢0A2, B2, C2n2=[34*sin⁡(π18)2-2]*n⁢⁢0 10. An asymmetric autotransformer/rectifier unit (ATRU) comprising: input terminals In1, In4, and In7 connected to the three-phase AC input voltage, wherein the three-phase AC input voltage is connected directly as an output of the asymmetric ATRU;output terminals Out2, Out3, Out5, Out6, Out8, and Out9 connected to provide AC output voltages;a first plurality of coils wound on a first leg of the autotransformer, connected to the input terminal In1 and output terminals Out6 and Out8, each coil of the first plurality of coils defined by a number of winding turns associated with the coil;a second plurality of coils wound on a second leg of the autotransformer, connected to the input terminal In4 and output terminals Out2 and Out9, each coil of the second plurality of coils defined by a number of winding turns associated with the coil; anda third plurality of coils wound on a third leg of the autotransformer, connected to the input terminal In7 and output terminals Out3 and Out5, each coil of the third plurality of coils defined by a number of winding turns associated with the coil; anda plurality of internal terminals T1-T6 for interconnecting the first, second and third plurality of coils in a desired configuration, wherein the asymmetric ATRU provides a first group of AC outputs provided at output terminals Out3, Out6, and Out9 that lag the three-phase AC input voltage provided directly as an output of the asymmetric ATRU, and second group of AC outputs provided at output terminals Out2, Out5, and Out8 that lead the three-phase AC input voltage provided directly as an output of asymmetric ATRU. 11. The asymmetric ATRU of claim 10, wherein the first plurality of coils includes coils A0, A0′, A1, A1′, and A2, the second plurality of coils includes coils B0, B0′, B1, B1′, and B2, and the third plurality of coils includes coils C0, C0′, C1, C1′, and C2. 12. The asymmetric ATRU of claim 11, wherein the first group of AC outputs provided at output terminals Out3, Out6, and Out9 lead the three-phase AC input voltages provided directly as an output of the asymmetric ATRU by 20°, respectively, and wherein the second group of AC outputs provided at output terminals Out2, Out5, and Out8 lag the three-phase AC input voltages provided directly as an output of the asymmetric ATRU by 20°. 13. The asymmetric ATRU of claim 12, wherein the coils A0, A2, and A0′ are connected in series between input terminals In1 and In4 via internal terminals T2 and T3, coils B0, B2, and B0′ are connected in series between input terminals In4 and In7 via internal terminals T4 and T5, and coils C0, C2, and C0′ are connected in series between input terminals In7 and In1 via internal terminals T6 and T1, wherein coil A1 is connected between internal terminal T5 and output terminal Out6, coil A1′ is connected between internal terminal T6 and output terminal Out8, coil B1 is connected between internal terminal T1 and output terminal Out9, coil B1′ is connected between internal terminal T2 and output terminal Out2, coil C1 is connected between internal terminal T3 and output terminal Out3, coil C1′ is connected between internal terminal T4 and output terminal Out5. 14. The asymmetric ATRU of claim 13, wherein the length of each of the first, second, and third plurality of coils is provided by the following table: CoilNumber of turnsA0, B0, C0n0A0′, B0′, C0′n0A1, B1, C1,n⁢⁢1=[3*sin⁡(π/9)4*sin⁡(π/18)2-12]*n⁢⁢0A1′, B1′, C1′n⁢⁢1=[3*sin⁡(π/9)4*sin⁡(π/18)2-12]*n⁢⁢0A2, B2, C2n⁢⁢2=[34*sin⁡(π/18)2-2]*n⁢⁢0.