Overvoltage snubber for grid tie inverter

1. An overvoltage snubber circuit configured to receive an alternating current (AC) overvoltage, comprising:

a first rectifier configured to convert the AC overvoltage to a direct current (DC) overvoltage;

a chopper circuit electrically connected to the first rectifier and configured to break up the DC overvoltage and to output a variable DC voltage; and

a resistor electrically connected to the chopper circuit and configured to dissipate energy of the variable DC voltage,

wherein the first rectifier is electrically connected to the resistor and configured to convert the variable DC voltage to a snubbed AC voltage,

wherein the overvoltage snubber circuit is located in a fuel cell system comprising:

a plurality of fuel cell modules are electrically connected to an inverter and configured to convert a DC voltage output of the plurality of fuel cell modules to an AC voltage,

an electrical grid circuit breaker electrically connected to an electrical grid and configured to interrupt an electrical connection between the inverter and the electrical grid,

a load configured to receive the AC voltage from the electrical grid and the inverter,

an electrical bus configured to transmit the AC voltage, and configured to electrically connect the inverter, the electrical grid circuit breaker, the load, and the overvoltage snubber circuit in parallel, and

wherein the overvoltage snubber circuit further comprises:

the first rectifier electrically connected to the electrical bus on an AC side of the first rectifier and electrically connected to a positive bus and a negative bus on a DC side of the first rectifier,

a pre-charge circuit electrically connected between the positive bus and the negative bus and electrically connected in parallel to an input of the chopper circuit via the negative bus, and

the resistor having a first and a second end, the first end of the resistor electrically connected to an output of the chopper circuit and the second end of the resistor electrically connected to the positive bus.

2. The overvoltage snubber circuit of claim 1 , wherein the pre-charge circuit is configured to reduce a rate of increase of power in the overvoltage snubber circuit in response to the overvoltage snubber circuit receiving the AC overvoltage.

3. The overvoltage snubber circuit of claim 1 , further comprising a controller electrically connected to the chopper circuit and configured to signal the chopper circuit to change a state of the chopper circuit, wherein the chopper circuit is configured to induce the overvoltage snubber circuit to receive the AC overvoltage when the chopper circuit is in a closed state and configured to break up the DC overvoltage by switching between the closed state and an open state.

4. The overvoltage snubber circuit of claim 1 , wherein the resistor is configured to dissipate energy of the variable DC voltage to approximately or below a designated threshold that indicates a power level manageable by the load.

5. The overvoltage snubber circuit of claim 1 , further comprising a filter capacitor electrically connected to the chopper circuit and configured to smooth out the DC overvoltage by storing energy of the DC overvoltage.