Systems and methods to provide enhanced diode bypass paths
View Patent ↗Systems and methods are herein disclosed for efficiently allowing current to bypass a group of solar cells having one or more malfunctioning or shaded solar cells without overwhelming a bypass diode. This can be done using a switch (e.g., a MOSFET) connected in parallel with the bypass diode. By turning the switch on and off, a majority of the bypass current can be routed through the switch, which is configured to handle larger currents than the bypass diode is designed for, leaving only a minority of the current to pass through the bypass diode.
1. A system, comprising:
a group of series-connected solar cells in a solar module, wherein
the solar module has a plurality of groups of solar cells, including the group of series-connected solar cells,
the plurality of groups are connected in series, and
solar cells in the group are series-connected between two nodes;
a bypass diode connected between the two nodes and configured to allow a current generated by the solar module to flow from a first node of the two nodes to a second node of the two nodes via the bypass diode and bypass the group of series-connected solar cells; and
a bypass switch having a MOSFET separate from the bypass diode and connected between the two nodes and configured to allow a bypass current to flow from the first node to the second node via the bypass switch and bypass:
the group of solar cells; and
the bypass diode.
2. The system of claim 1 , wherein current passes through the bypass switch more often than current passes through the bypass diode.
3. The system of claim 1 , further comprising a current transformer configured to generate a power supply input voltage to a power supply when a current passing through the bypass diode increases.
4. The system of claim 3 , wherein the power supply input voltage charges a capacitor of the power supply.
5. The system of claim 4 , further comprising a latch circuit configured to:
discharge the power supply into a first gate terminal and a second gate terminal, when a power supply input voltage is greater than a first voltage threshold; and
prevent the power supply from discharging into the first gate terminal and the second gate terminal, when the power supply input voltage is less than a second voltage threshold lower than the first voltage threshold;
wherein the latch circuit provides a control signal to control the bypass switch.
6. The system of claim 1 , further comprising a controller for turning the bypass switch on, when the bypass diode, is forward biased.
7. The system of claim 6 , wherein the controller turns the bypass switch on based on the bypass current through the bypass diode.
8. The system of claim 6 , wherein the controller turns the bypass switch on based on a voltage drop across the bypass diode, wherein the voltage drop is caused by the bypass current passing through the bypass diode.
9. The system of claim 6 , wherein the controller periodically turns the bypass switch on and off.
10. The system of claim 6 , wherein the controller:
holds the bypass switch on for a period of time;
turns the bypass switch off; and
turns the bypass switch back on when the bypass current passes through the bypass diode.
11. The system of claim 1 , further comprising:
a control circuit coupled with the bypass switch, wherein the control circuit has a power supply;
a current transformer coupled with the bypass diode and the power supply to charge the power supply using a current passing through the bypass diode; and
a latch circuit coupled to the power supply to control the bypass switch, wherein when the power supply has sufficient power, the latch circuit is configured to close the bypass switch to allow the bypass current to bypass:
the group of solar cells; and
the bypass diode.