FILTER COMPONENT REDUCTION
Reduction as well as elimination of the use of discrete inductors or other filtering components for photovoltaic (PV) Module-Level Power Electronics (MLPE) is provided. This reduction may serve to promote two-dimensional circuit topology designs of MLPEs as well as promote efficiencies and reliability linked to diminished or eliminated inductor, or other filtering component(s), presence or use in MLPEs or related components or systems.
1 . A photovoltaic (PV) system comprising:
a plurality of PV modules;
a plurality of dc-dc converters, each of the plurality of dc-dc converters operatively connected to at least one of the PV modules;
a dc-ac inverter, each of the dc-dc converters operatively connected in series to the dc-ac inverter through an electrical conduit, the electrical conduit providing a first wire inductance to the PV system;
wherein the dc-ac inverter comprises a capacitor providing a capacitance to the PV system; and,
wherein the first wire inductance and the inverter capacitance operate as an output filter of the PV system.
2 . The system of claim 1 , wherein the dc-ac inverter further comprises an inductor providing a second inductance to the PV system.
3 . The system of claim 1 , wherein the dc-dc converter is a buck converter.
4 . The system of claim 3 , wherein the buck converter comprises a first and a second switch.
5 . The system of claim 3 , wherein the buck converter does not comprise an output filter.
6 . The system of claim 3 , wherein the buck converter does not comprise an output inductor.
7 . The system of claim 3 , wherein the buck converter does not comprise an output capacitor.
8 . A method of operating a photovoltaic (PV) system, the PV system comprising:
a plurality of PV modules;
a plurality of dc-dc converters, each of the plurality of dc-dc converters operatively connected to at least one of the PV modules of the plurality of PV modules;
a dc-ac inverter, each of the dc-dc converters operatively connected in series to the dc-ac inverter through an electrical conduit, the electrical conduit providing a first wire inductance to the PV system;
wherein the dc-ac inverter comprises a capacitor providing a capacitance to the PV system; and,
wherein the first wire inductance and the inverter capacitance operate as an output filter of the PV system,
the method comprising:
providing a synchronization signal to each of the dc-dc converters; and
phase-shifting the output voltages of each of the dc-dc converters based on the synchronization signal.
9 . The method of claim 8 wherein the plurality of dc-dc converters totals N in number and wherein the output voltages of the each of the dc-dc converters are phase-shifted by a cycle length times the inverse of one-half of N.
10 . The method of claim 8 further comprising:
phase-shifting the output voltages of two or more of the dc-dc converters by a multiplier, the multiplier serving to cancel ripple in an output of one or more of the dc-dc converters.
11 . The method of claim 8 further comprising:
using a first duty cycle to control switches in a first dc-dc converter of the plurality of dc-dc converters; and
using a second duty cycle to control switches in a second dc-dc converter of the plurality of dc-dc converters;
wherein the first duty cycle is different than the second duty cycle.
12 . The method of claim 8 further comprising:
during a commissioning of converters of the plurality of dc-dc converters, assigning a relative time shift to each of the converters of the plurality, the time shift serving to stager relative switch firing times of converters of the plurality of dc-dc converters.
13 . The method of claim 12 wherein a value indicating the relative time shift to be assigned is received at the PV system from an external communication network.
14 . The method of claim 8 further comprising:
assigning a relative time shift to each of the converters of the plurality, the time shift serving to stager relative switch firing times of converters of the plurality of dc-dc converters.
15 . A first dc-dc converter comprising:
a microcontroller,
a plurality of switches,
a gate drive circuit, and
a sensing circuit,
the microcontroller configured to assign a relative time shift to gate signals being sent by the gate drive circuit to one or more switches of the plurality of switches, the time shift serving to stager relative switch firing times of the plurality of switches relative to a second and a third plurality of switches located at a second and third dc-dc converter, the first dc-dc converter, the second dc-dc converter and the third dc-dc converter connected in series to each other.
16 . The first dc-dc converter of claim 15 wherein the microcontroller is further configured to receive a duty cycle for the plurality of switches and to send instructions to the gate driving to apply the received duty cycle when driving the plurality of switches, the plurality of switches comprising a first switch and a second switch.
17 . The first dc-dc converter of claim 15 wherein the switches of the plurality of switches are MOSFETs.
18 . The first dc-dc converter of claim 15 further comprising:
a dc voltage input, the dc voltage input coupled to the plurality of switches and configured to receive a dc voltage from at least one photovoltaic cell.
19 . The first dc-dc converter of claim 18 wherein the dc voltage input is receiving a dc voltage from a plurality of photovoltaic cells.
20 . The first dc-dc converter of claim 15 wherein the microcontroller is further configured to receive the relative time shift to gate signals to be assigned over a network and in response to an initial system initiation announcement signal.