초록 ▼

Various methods and apparatus are described for a photovoltaic system. In an embodiment, pluralities of three-phase Alternating Current (AC) inverter circuits electrically connect into a common three phase AC output. Each of those inverters receives a bipolar DC voltage supplied from its own set of

Various methods and apparatus are described for a photovoltaic system. In an embodiment, pluralities of three-phase Alternating Current (AC) inverter circuits electrically connect into a common three phase AC output. Each of those inverters receives a bipolar DC voltage supplied from its own set of Concentrated PhotoVoltaic (CPV) modules.

대표청구항 ▼

1. An inverter apparatus for converting power from a bipolar photovoltaic source to 3-phase AC power, comprising: a bipolar DC input port, a DC capacitive energy storage element, a single-stage DC to 3-phase power converter, AC line isolation contactors, a 3-phase AC output port and a control circui

1. An inverter apparatus for converting power from a bipolar photovoltaic source to 3-phase AC power, comprising: a bipolar DC input port, a DC capacitive energy storage element, a single-stage DC to 3-phase power converter, AC line isolation contactors, a 3-phase AC output port and a control circuit;wherein the bipolar DC input port is configured to accept two monopolar photovoltaic source circuits, where a first conductor of each of said monopolar photovoltaic source circuits is coupled to earth ground and where a second conductor of each of said monopolar photovoltaic source circuits are collectively of opposite polarities and coupled across a DC capacitive energy storage bus;wherein the DC capacitive energy storage element further comprises film type capacitors;wherein the DC capacitive energy storage element is coupled to an input of the single-stage DC to 3-phase power converter;wherein the AC line isolation contactors are configured to make or break a coupling between an output of the single-stage DC to 3-phase power converter and the 3-phase AC output port under control of the control circuit; andwherein the 3-phase AC output port is connected to an electrical utility grid. 2. The inverter apparatus for converting power from a bipolar photovoltaic source to 3-phase AC power of claim 1, further comprising: a first inverter circuit of a plurality of three-phase AC inverter circuits; anda second inverter circuit, where a first string of PhotoVoltaic (PV) cells all from the East side of a solar array feeds the first inverter circuit, and a second string of PV cells all from the West side of the solar array feeds the second inverter circuit, and this grouping of similarly shaded modules into the same string of PV cells feeding a particular inverter tends to allow a more narrow input working voltage into that three-phase AC inverter circuit, which avoids a DC-to-DC boost stage requirement between an input DC voltage circuit portion and an AC conversion portion in that three-phase AC inverter circuit. 3. The inverter apparatus for converting power from a bipolar photovoltaic source to 3-phase AC power of claim 1, further comprising: a single stage DC-to-AC voltage conversion circuitry containing a plurality of three phase AC inverter circuits electrically connecting into a common three-phase AC output, where the three-phase AC inverter circuitry has no need for supplemental input DC voltage level boosting strategies, including a DC input boost stage to increase the DC input voltage level to a higher DC voltage level for the DC to AC conversion, because the supplied bipolar DC input voltage level from the set of PV modules is high enough to directly convert to an AC working voltage level, and provides a three-phase 480 VAC output voltage level from the inverter circuit without the DC input boost stage or a step up transformer after the inverter portion. 4. The inverter apparatus for converting power from a bipolar photovoltaic source to 3-phase AC power of claim 1, further comprising: a first solar array with PV cells on the East side and the West side of the solar array contained in the PV modules supplying the bipolar DC voltage to a plurality of three-phase AC inverters, and these two or more three-phase AC inverters per this single solar array account for voltage differences coming out of the set of PV modules on the East side of the solar array and the voltage coming out of the set of PV modules on the West side of the solar array, which allows a first three phase AC inverter connected to the set of PV modules on the East side to operate at the bipolar DC input voltage level coming from the East side independent of what bipolar DC input voltage level is being produced and supplied by the set of PV modules on the West side to a second three phase AC inverter, and vice versa. 5. The inverter apparatus for converting power from a bipolar photovoltaic source to 3-phase AC power of claim 1, further comprising: a plurality of PV cells are contained and connected electrically in series in each module in the set of PV modules and enough are connected electrically in series in a string of PV cells from the set of modules to allow the bipolar DC voltage level from the PV modules to allow the bipolar DC input voltage level from the PV string of cells to be high enough to directly convert the DC voltage to the working AC voltage level but lower than a maximum DC voltage limit set by the National Electric Code (NEC). 6. The inverter apparatus for converting power from a bipolar photovoltaic source to 3-phase AC power of claim 5, further comprising: an input DC grounding circuit located in each inverter circuit that electrically couples to the strings of PV cells from a solar array, where the electrical components in an input DC Grounding Circuit cause the DC power from the strings of PV cells to be connected to ground when the inverter circuit is not producing three phase AC power out and the electrical components in the input DC Grounding circuit also use 1) a contact 2) switch or 3) both to create a dynamic ground/common zero VDC reference point for the bipolar DC voltage supplied to that inverter from its set of PV modules. 7. The inverter apparatus for converting power from a bipolar photovoltaic source to 3-phase AC power of claim 5, further comprising: a voltage level detection circuit monitoring the input bipolar DC input voltage level to one or more three phase AC inverter circuits;one or more switching devices; andwhere two or more sets of PV modules are electrically strung together to supply bipolar DC input voltage to a particular three phase AC inverter circuit, where a first switching device may actuate, by electrically opening a contact or switch, closing a contact or switch, by the first switching device starting to conduct, and any combination of the three, to create an electrically parallel path around one or more of the sets of the PV modules to effectively bypass that series of PV modules for that inverter, and by the voltage level detection circuit monitoring the input bipolar DC input voltage level, a staggering of an amount of PV modules supplying bipolar DC voltage level to that inverter is controlled by the operation of the one or more switching devices, where less than all of the sets of PV modules electrically connecting to the particular three phase AC inverter circuit initially contribute to the input bipolar DC voltage supplied to that particular three phase AC inverter circuit to ensure that at all times a maximum DC voltage input level into the inverter is below the NEC limit. 8. The inverter apparatus for converting power from a bipolar photovoltaic source to 3-phase AC power of claim 1, where a plurality of three phase AC inverter circuits are each contained in their own sub assembly with connections that are easily coupled to or slid into the electrical connections making replacement, troubleshooting, and servicing easier, and where a single solar array containing sets of PV modules that supply the DC power to the plurality of inverter circuits. 9. The inverter apparatus for converting power from a bipolar photovoltaic source to 3-phase AC power of claim 5, wherein wiring is installed and connections are made between the PV cells in each PV module in the manufacturing facility itself, which eliminates individually wiring each of the hundreds of PV cells in each solar array during the field installation of the solar array, where the PV cells in each module are wired in an electrically series-parallel arrangement. 10. The inverter apparatus for converting power from a bipolar photovoltaic source to 3-phase AC power of claim 1, further comprising: a plurality of PV cells contained and connected electrically in series in each module in a set of PV modules; anda bypass diode on each individual PV cell and electrically in parallel with that individual PV cell so when that cell is being shaded or fails, the electrically series connected PV cell in that PV string does not act as a load to significantly knock down the DC voltage output from that PV module. 11. The inverter apparatus for converting power from a bipolar photovoltaic source to 3-phase AC power of claim 1, further comprising: a plurality of PV cells contained and connected electrically in series in a set of PV modules to form a string of PV cells, where multiple strings of PV cells are formed and organized coming from a solar array to a plurality of three-phase AC inverter circuits; anda multiplicity of Maximum Power Point Tracking sense circuits controlling the PV cells in the solar array, each Maximum Power Point Tracking sense circuit controlling the DC power associated with its own string of PV cells that are configured to operate over a wide temperature range from −25 degrees C. to +55 degrees C., with a DC voltage operating window of 450 VDC up to 600 VDC to maximize the power coming out of that string, and where the PV cells are multi-junction solar cells. 12. The inverter apparatus for converting power from a bipolar photovoltaic source to 3-phase AC power of claim 1, further comprising: a controller to control the gating of a space vector modulated bridge switching circuit in a first inverter of a plurality of three phase AC inverter circuits; andFrequency and Voltage synchronization signals and wiring between the plurality of three phase AC inverter circuits feeding the common AC output to make sure the multiple inverter circuits generate the same AC voltage level and at the same frequency, and with synchronized phases of AC. 13. The inverter apparatus for converting power from a bipolar photovoltaic source to 3-phase AC power of claim 1, further comprising: a plurality of PV cells contained and connected electrically in series in a set of PV modules to form two or more strings of PV cells, where each string of PV cells is controlled by its own Maximum Power Point Tracking (MPPT) sense circuit in a three phase AC inverter circuit; andfeedback circuitry in the inverter circuitry configured for use between the MPPT sense circuitry in the inverter and a solar tracking calibration algorithm for a solar array, where after each movement of the solar array for each calibration point, then a signal is sent to the MPPT sense circuit for each string of PV cells supplying power from that solar array to reestablish the Maximum Power Point for that particular string, and when the MPPT sense circuits for all of the strings supplying power to those multiple inverters report back that they have completed their MPPT functionality to establish the Maximum Power Point for that particular string, then a signal is sent to the solar tracking calibration algorithm to determine the power coming out of the solar array for that coordinate position. 14. The inverter apparatus for converting power from a bipolar photovoltaic source to 3-phase AC power of claim 1, wherein two or more of a plurality of three phase AC inverter circuits have a pulse modulated switching circuit that generates a continuous three-phase power that avoids any need for large capacitance value electrolytic capacitors and uses film based capacitors instead due to an overall lower need for capacitance in the three phase AC inverter circuitry. 15. The inverter apparatus for converting power from a bipolar photovoltaic source to 3-phase AC power of claim 1, further comprising: a solar array with PV cells on the East side and the West side of the solar array contained in the PV modules supplying bipolar DC voltage to a plurality of three-phase AC inverters; andone or more Maximum Power Point Tracking (MPPT) sense circuits associated with each three phase AC inverter circuit, where each inverter has its own MPPT sense circuit per string of PV cells electrically coupling to that inverter to maximize the DC power coming from the string of PV cells contained in the PV modules, where a first MPPT sense circuit maximizes the DC power coming from a first string of PV cells located exclusively on the East side of the solar array, and a second MPPT sense circuit maximizes the DC power coming from a second string of PV cells located exclusively on the West side of the solar array. 16. The inverter apparatus for converting power from a bipolar photovoltaic source to 3-phase AC power according to claim 1, further comprising: a DC grounding circuit configured to allow for uncoupling said first conductor of each of said monopolar photovoltaic source circuits from earth ground when the inverter apparatus is producing power. 17. The inverter apparatus for converting power from a bipolar photovoltaic source to 3-phase AC power according to claim 1, further comprising: a second set of AC line isolation contactors connected in series with the AC line isolation contactors to provide isolation redundancy. 18. The inverter apparatus for converting power from a bipolar photovoltaic source to 3-phase AC power according to claim 1, further comprising: a DC ground fault detector and interrupter. 19. The inverter apparatus for converting power from a bipolar photovoltaic source to 3-phase AC power according to claim 1, further comprising: a diode between the bipolar DC input port and the DC capacitive energy storage element configured to allow preventing reverse current flow at the bipolar DC input port.