Over-voltage protection circuit
View Patent ↗An over-voltage protection circuit is disclosed herein for protection against over-voltage of an energy storage device while charging. The circuit operates within the operational limits of a battery-operated device, such as a mobile or handheld device. The over-voltage protection circuit comprises an over-voltage protection device, and an over-voltage protection controller. The controller allows current to flow to the over-voltage protection device only when an energy storage device is experiencing over-voltage. In allowing current to flow to the over-voltage protection device only when the voltage across the energy storage device is above a predetermined voltage, power conservation is achieved.
1. An over-voltage protection circuit for connection to a charging circuit for maintaining a voltage across a plurality of electrical energy storage devices at or below a predetermined voltage during charging, comprising:
a first electrical energy storage device connected from a top voltage rail to a primary junction;
a second electrical energy storage device connected from the primary junction to a bottom voltage rail; and
an inductor;
the over-voltage protection circuit to perform a first procedure in which a charge is drawn from the first electrical energy storage device through the inductor to energize the inductor, for the inductor to then cause a current that charges the second storage device;
the over-voltage protection circuit to perform a second procedure in which a charge is drawn from the second electrical energy storage device through the inductor to energize the inductor, for the inductor to then cause a current that charges the first storage device; and
a dissipation controller to perform a third procedure in which a charge is discharged from the energized inductor upon detection of an over-voltage condition.
2. The over-voltage protection circuit of claim 1 , further comprising:
a first diode and a first switch connected from the top rail to a secondary junction;
a second diode and a second switch connected from the secondary junction to the bottom rail, with the inductor connected from the primary junction to the secondary junction;
the over-voltage protection circuit being configured in the first procedure to:
close the first switch to conduct current from the top rail, through the first switch and the inductor, to the primary junction to energize the inductor; and
open the first switch, causing the inductor to induce a temporary current to flow from the bottom rail through the second diode and the inductor, to the primary junction; and
the over-voltage protection circuit being configured in the second procedure to:
close the second switch to conduct current from the primary junction, through the second switch and the inductor, to the bottom rail to energize the inductor; and
open the second switch, causing the inductor to induce a temporary current to flow from the primary junction through the first diode and the inductor, to the top rail.
3. The circuit of claim 1 , wherein the first electrical energy storage device is a capacitor.
4. The circuit of claim 1 , wherein the first electrical energy storage device is a battery.
5. An over-voltage protection circuit for connection to a charging circuit for maintaining a voltage across a plurality of electrical energy storage devices at or below a predetermined voltage during charging, comprising:
a first electrical energy storage device connected from a top voltage rail to a primary junction;
a second electrical energy storage device connected from the primary junction to a bottom voltage rail;
an inductor;
a dissipation controller to perform a dissipation procedure in which a charge is discharged from the energized inductor upon detection of an over-voltage condition;
the over-voltage protection circuit to perform a first procedure in which a charge is drawn from the first electrical energy storage device through the inductor to energize the inductor, for the inductor to then cause a current that charges the second electrical energy storage device; and
the over-voltage protection circuit to perform a second procedure in which a charge is drawn from the second electrical energy storage device through the inductor to energize the inductor, for the inductor to then cause a current that charges the first electrical energy storage device.
6. The over-voltage protection circuit of claim 5 , further comprising:
a first diode, the first diode and the first switch connected from the top rail to a secondary junction;
a second diode, the second diode and the second switch connected from the secondary junction to the bottom rail, with the inductor connected from the primary junction to the secondary junction;
the over-voltage protection circuit being configured in the first procedure to:
close the first switch to conduct current from the top rail, through the first switch and the inductor, to the primary junction to energize the inductor; and
open the first switch, causing the inductor to induce a temporary current to flow from the bottom rail through the second diode and the inductor, to the primary junction; and
the over-voltage protection circuit being configured in the second procedure to:
close the second switch to conduct current from the primary junction, through the second switch and the inductor, to the bottom rail to energize the inductor; and
open the second switch, causing the inductor to induce a temporary current to flow from the primary junction through the first diode and the inductor, to the top rail.
7. The over-voltage protection circuit of claim 5 , further comprising a voltage sensor that detects the over-voltage condition and that closes the first switch in response to the first storage device being excessively charged, and closes the second switch in response to the second storage device being excessively charged.
8. The over-voltage protection circuit of claim 5 , configured to alternate between the first procedure and the second procedure at a regular time interval.
9. A method of operating an over-voltage protection circuit electrical circuit for charging a plurality of electrical energy storage devices that includes a first electrical energy storage device connected from a top voltage rail to a primary junction, a second electrical energy storage device connected from the primary junction to a bottom voltage rail, an inductor, a first diode connected from the top rail to a secondary junction, and a second diode connected from the secondary junction to the bottom rail, with the inductor connected from the primary junction to the secondary junction, the method comprising:
performing a first procedure in which a charge is drawn from the first electrical energy storage device through the inductor to energize the inductor, for the inductor to then cause a current that charges the second electrical energy storage device; and
performing a second procedure in which a charge is drawn from the second electrical energy storage device through the inductor, for the inductor to then cause a current that charges the first electrical energy storage device; and
discharging the energized inductor upon detection of an over-voltage condition.
10. The method of claim 9 , wherein the first electrical energy storage device is a capacitor.
11. The method of claim 9 , wherein the first electrical energy storage device is a battery.
12. The method of claim 9 , wherein the first procedure and the second procedure are performed alternatingly at a regular time interval.