Adjustable AC/DC conversion topology to regulate an isolated DC load with low AC ripple

1. A system, comprising:

a plurality of power converter modules individually including a first output to provide a DC output signal, the individual power converter modules including:

an adjustable voltage, adjustable frequency pulse width modulation (PWM) inverter to generate a first AC signal according to a desired fundamental inverter AC output frequency and a voltage reference,

an LC sinewave filter, including an input to receive the first AC signal, and an output to provide a filtered AC signal,

a multiphase isolation transformer, including a primary winding to receive the filtered AC signal, and a multiphase secondary to provide a plurality of isolated AC signals,

a multi-pulse diode bridge rectifier, including a plurality of rectifier inputs to receive the plurality of isolated AC signals, and a rectifier output to provide a DC rectifier output signal,

an output filter, including an input to receive the DC rectifier output signal, and an output to provide a filtered DC rectifier output signal, and

a blocking diode, including an anode connected to the output of the output filter, and a cathode to provide the filtered DC rectifier output signal;

wherein the PWM inverter regulates the filtered DC rectifier output signal by adjusting the first AC signal at least partially according to a feedback signal from the output filter.

2. The system of claim 1 , wherein the PWM inverter provides the first AC signal at a signal frequency in a range of about 120 Hz to about 600 Hz.

3. The system of claim 2 , wherein the PWM inverter provides the first AC signal at a signal frequency in a range of about 180 Hz to about 300 Hz.

4. The system of claim 2 , wherein the PWM inverter provides the first AC signal at a signal frequency of about 180 Hz.

5. The system of claim 1 , wherein the PWM inverter includes a six pulse inverter switching circuit, including three pairs of upper and lower switching devices individually coupled between a DC bus node and a corresponding one of three output nodes to provide the first AC signal as a three phase AC signal.

6. The system of claim 1 , wherein the plurality of power converter modules operate according to a profile that defines setpoints for the individual power converter modules.

7. The system of claim 1 , wherein the multiphase isolation transformer is a six-phase transformer with an electrostatic shield connected to a ground.

8. The system of claim 1 , wherein the multiphase isolation transformer is a nine-phase transformer with an electrostatic shield connected to a ground.

9. The system of claim 1 , further comprising an input rectifier to provide a DC input signal to the PWM inverter.

10. The system of claim 1 , wherein the LC sinewave filter comprises an inductor associated with each phase, and a capacitor connected between a respective one of the inductors for each phase and a common connection.

11. The system of claim 1 , wherein the LC sinewave filter is an LCL filter having first and second inductors associated with each phase, and a capacitor connected between a respective one of the second inductors for each phase and a common connection.

12. A power converter to provide a DC output signal, comprising:

an adjustable voltage, adjustable frequency pulse width modulation (PWM) inverter to generate a first AC signal according to a desired fundamental inverter AC output frequency and a voltage reference;

an LC sinewave filter, including an input to receive the first AC signal, and an output to provide a filtered AC signal;

a multiphase isolation transformer, including a primary winding to receive the filtered AC signal, and a multiphase secondary to provide a plurality of isolated AC signals;

a multi-pulse diode bridge rectifier, including a plurality of rectifier inputs to receive the plurality of isolated AC signals, and a rectifier output to provide a DC rectifier output signal;

an output filter, including an input to receive the DC rectifier output signal, and an output to provide a filtered DC rectifier output signal; and

a blocking diode, including an anode connected to the output of the output filter, and a cathode to provide the filtered DC rectifier output signal;

wherein the PWM inverter regulates the filtered DC rectifier output signal by adjusting the first AC signal at least partially according to a feedback signal from the output filter.

13. The power converter of claim 12 , wherein the PWM inverter provides the first AC signal at a signal frequency in a range of about 120 Hz to about 600 Hz.

14. The power converter of claim 13 , wherein the PWM inverter provides the first AC signal at a signal frequency in a range of about 180 Hz to about 300 Hz.

15. The power converter of claim 13 , wherein the PWM inverter provides the first AC signal at a signal frequency of about 180 Hz.

16. The power converter of claim 12 , wherein the PWM inverter includes a six pulse inverter switching circuit, including three pairs of upper and lower switching devices individually coupled between a DC bus node and a corresponding one of three output nodes to provide the first AC signal as a three phase AC signal.

17. The power converter of claim 12 , wherein the multiphase isolation transformer is a six-phase transformer with an electrostatic shield connected to a ground.

18. The power converter of claim 12 , wherein the multiphase isolation transformer is a nine-phase transformer with an electrostatic shield connected to a ground.

19. The power converter of claim 12 , further comprising an input rectifier to provide a DC input signal to the PWM inverter.

20. A method, comprising:

generating a plurality of DC voltage signals according to a profile defining setpoints for individual power converter modules, including for each power converter module:

generating a first AC signal at a frequency in a range of about 120 Hz to about 600 Hz using a pulse width modulation (PWM) inverter,

filtering the first AC signal to generate a filtered AC signal using an LC sinewave filter,

generating a plurality of isolated AC signals according to the filtered AC signal using a multiphase isolation transformer,

rectifying the isolated AC signals to generate a DC rectifier output signal using a multi-pulse diode bridge rectifier,

filtering the DC rectifier output signal to generate a filtered DC rectifier output signal using an output filter,

regulating the filtered DC rectifier output signal by adjusting the first AC signal at least partially according to a feedback signal from the output filter, and

providing the filtered DC rectifier output through a blocking diode.