Pi source inverter-converter for hybrid electric vehicles

1. A system for reducing a resonant oscillation on a direct current bus of a power inverter/converter for an electric machine having a variable frequency drive, the system comprising:

a battery;

a first capacitor connected in parallel with the battery;

an inductor connected in series with the first capacitor;

a first diode connected in series with the inductor;

a second diode connected in parallel with the inductor and the first diode;

a second capacitor connected in series with the first diode; and

a starter-generator connected to the second capacitor;

wherein:

during a re-generation mode for charging the battery, a re-generation current flows from the starter-generator to the battery, passing through the first diode and the inductor and bypassing the second diode; and

during a motor mode, a motor current flows from the battery to the starter-generator, passing through the second diode and bypassing the first diode and the inductor.

2. The system of claim 1 , wherein the first capacitor and the inductor form an L-C filter.

3. The system of claim 1 , wherein during the re-generation mode for charging the battery, the re-generation current flows through the first capacitor and the inductor respectively.

4. The system of claim 1 , further comprising a power inverter/converter connected between the starter-generator and the second capacitor.

5. The system of claim 4 , wherein the power inverter/converter comprises six MOSFETS each including a diode.

6. The system of claim 4 , wherein:

during the motor mode, the power inverter/converter includes an inverter from DC to 3-phase AC sinusoidal; and

during the re-generation mode, the power inverter/converter includes a converter from 3-phase AC sinusoidal to DC.