INVERTER PRE-CHARGE CIRCUIT

1 . A pre-charge circuit, comprising:

an input configured to connect to a DC power source;

an output configured to connect to the input of an inverter;

a capacitor coupled to the output;

a resistive branch including a pre-charge switch and a limiting resistor coupled in series between the input and the output; and

a shunting branch coupled in parallel with the resistive branch including one or more solid-state switches connected between the input and the output.

2 . The pre-charge circuit of claim 1 , including multiple solid-state switches stacked in parallel within the shunting branch between the input and the output.

3 . The pre-charge circuit of claim 1 , wherein the solid-state switches are field effect transistors (FETs) or insulated-gate bipolar transistors (IGBTs).

4 . The pre-charge circuit of claim 1 , wherein the pre-charge switch comprises one or more solid-state switches.

5 . The pre-charge circuit of claim 1 , wherein a digital signal processor (DSP) is configured to:

close the pre-charge switch enabling the DC power source to charge the capacitor through the resistive branch;

activate the solid-state switches after charging the capacitor shunting the output of the DC power source to the input of the inverter;

reopen the pre-charge switch after activating the solid-state switches; and

maintain activation of the solid-state switches while operating the inverter.

6 . The pre-charge circuit of claim 5 , wherein the digital signal processor (DSP) is further configured to:

measure an input voltage at the input of the pre-charge circuit;

measure an output voltage at the output of the pre-charge circuit; and

activate the solid-state switches in the shunting branch when the output voltage is substantially and same as the input voltage.

7 . The pre-charge circuit of claim 5 , wherein the DSP controls the switching of the H-bridges.

8 . The pre-charge circuit of claim 5 , wherein the DSP is located in a power conversion system (PCS) used for converting DC power from a battery into AC power.

9 . The pre-charge circuit of claim 5 , wherein the DSP is further configured to:

close the pre-charge switch based on a request to leave a DC power source idle state; and

open the solid-state switches based on a request to enter the DC power source idle state.

10 . The pre-charge circuit of claim 5 , including a driver coupled to the DSP for activating the solid-state switches.

11 . The pre-charge circuit of claim 1 , wherein the output is coupled to a DC bus in a distributed energy resource system.

12 . A power conversion system (PCS) for converting between DC power and AC power, comprising:

an inverter including an output coupled at an AC bus;

a pre-charge circuit coupled between an output of a DC power source and an input of the inverter, the pre-charge circuit including solid-state switches and capacitors for pre-charging the input of the inverter; and

a digital signal processor (DSP) coupled to the inverter for controlling the conversion between DC power and AC power and coupled to the pre-charge circuit to control the pre-charging at the input of the inverter.

13 . The PCS of claim 12 , wherein the pre-charge circuit includes:

an input connected to the output of the DC power source;

an output connected to the input of the inverter and the capacitors;

a resistive branch including a pre-charge switch and a limiting resistor coupled in series between the input and the output; and

a shunting branch coupled in parallel with the resistive branch including solid-state switches connected between the input and the output.

14 . The PCS of claim 13 , wherein the output of the pre-charge circuit is coupled to a DC bus in a distributed energy resource system.

15 . The PCS of claim 13 , wherein the DSP is configured to:

close the pre-charge switch to charge the capacitor with the DC power source through the resistive branch;

activate the solid-state switches after charging the capacitor;

reopen the pre-charge switch after activating the solid-state switches; and

keep the solid-state switches activated while controlling the inverter.

16 . The PCS of claim 15 , wherein the DSP is further configured to:

monitor an input voltage at the input of the pre-charge circuit;

monitor an output voltage at the output of the pre-charge circuit; and

activate the solid-state switches when the output voltage is substantially the same as the input voltage.

17 . The PCS of claim 13 , wherein the DSP is further configured to:

close the pre-charge switch based on a request to activate the DC power source; and

open the solid state-switches based on a request to deactivate the DC power source.

18 . The PCS of claim 12 , including a driver coupled to the DSP for activating the solid-state relays.

19 . The PCS of claim 13 , wherein:

the solid-state switches in the shunting branch are connected in parallel between the input and the output of the pre-charge circuit; and

the pre-charge switch in the resistive branch comprises one or more solid-state switches coupled in parallel between the input of the pre-charge circuit and the limiting resistor.

20 . The PCS of claim 12 , wherein the solid-state switches are field effect transistors (FETs) or insulated-gate bipolar transistors (IGBTs).