Hybrid charger and inverter system
An electrical system can include an isolated bidirectional converter (having an input couplable to a grid connection and an output couplable to a battery) and an isolated converter (having an input coupled to the input of the isolated bidirectional converter and couplable to the grid connection, with an AC output coupled to a convenience outlet). The electrical system can further include a controller that controls operation of the converters to operate in one of a plurality of modes including a charging mode in which the isolated bidirectional converter operates in a forward direction to charge the battery and the non-isolated converter powers the convenience outlet from the grid connection, and a non-charging mode in which the isolated bidirectional converter operates in a reverse direction to power the non-isolated converter from the battery and the non-isolated converter powers the convenience outlet.
1. An electrical system comprising:
an isolated bidirectional converter having an input couplable to an AC grid connection and an output couplable to a battery;
a non-isolated converter having an input coupled to the input of the isolated bidirectional converter and selectively couplable to the AC grid connection and an AC output coupled to a convenience outlet;
a switch that selectively couples the input of the isolated bidirectional converter and the input of the non-isolated converter to the AC grid connection; and
a controller configured to toggle the switch and control operation of the isolated bidirectional converter and the non-isolated converter to operate in one or more of a plurality of modes including:
a charging mode in which the isolated bidirectional converter operates in a forward direction to charge the battery and the non-isolated converter powers the convenience outlet from the grid connection; and
a non-charging mode in which the isolated bidirectional converter operates in a reverse direction to power the non-isolated converter from the battery and the non-isolated converter powers the convenience outlet, wherein the non-charging mode includes at least one of:
a first discharging mode in which the isolated bidirectional converter is operated in the reverse direction to produce a DC output voltage having a magnitude tracking the battery voltage;
a second discharging mode in which the isolated bidirectional converter is operated in the reverse direction to produce a DC output voltage having a magnitude suitable for the convenience outlet; and
a third discharging mode in which the isolated bidirectional converter is operated in the reverse direction to produce a DC output voltage having a magnitude corresponding to a voltage of the AC grid.
2. The electrical system of claim 1 wherein the switch is a single pole switch.
3. The electrical system of claim 1 wherein:
in the charging mode the controller closes the switch; and
in the discharging mode the controller opens the switch.
4. The electrical system of claim 1 wherein the charging mode includes at least one of a power factor correction mode and a harmonics compensation mode, wherein:
in the power factor correction mode the isolated bidirectional converter is operated to correct the power factor of a load coupled to the convenience outlet such that the grid connection sees a unity power factor; and
in the harmonics compensation mode the isolated bidirectional converter is operated to compensate for harmonics introduced by the load coupled to the convenience outlet.
5. The electrical system of claim 1 wherein:
in the first discharging mode the isolated bidirectional converter operates as a pass-through inverter;
in the second discharging mode the isolated bidirectional converter performs regulation of the AC output voltage for the convenience outlet; and
in the third discharging mode the isolated bidirectional converter operates as a fixed ratio inverter.
6. The electrical system of claim 1 wherein the non-isolated converter comprises:
a stack of four switching devices, wherein an input of the non-isolated converter is coupled across the stack of four switching devices, and an output of the non-isolated converter is taken from a connection point of first and second switching devices of the stack and a junction of third and fourth switching devices of the stack;
input capacitors coupled in series across the input of the non-isolated converter, with a connection point of the input capacitors coupled to a connection point of the second and third switching devices; and
at least one output filter inductor and at least one output filter capacitor coupled to the output of the non-isolated converter.
7. The electrical system of claim 6 wherein the non-isolated converter further comprises a resonant tank made up of at least one resonant capacitor and at least one resonant inductor, wherein the resonant tank facilitates zero voltage switching of the switching devices.
8. The electrical system of claim 1 wherein the non-isolated converter comprises:
a plurality of bidirectional switching devices, wherein an input of the non-isolated converter is coupled across the bidirectional switching devices and an output of the non-isolated converter is taken from a connection point of the bidirectional switching devices;
at least one input capacitor coupled across the input of the non-isolated converter; and
at least one output filter inductor and at least one output filter capacitor coupled to the output of the non-isolated converter.
9. The electrical system of claim 8 wherein the bidirectional switches are configured as a full bridge converter.
10. The electrical system of claim 8 wherein the bidirectional switches are configured as a half bridge converter.