US 6,806,686 B1 · Charge balancing circuit

Abstract

A charge balancing circuit is disclosed that is configured to provide charge balancing for a bank of series connected charge storage devices such as capacitors. One embodiment of the charge balancing circuit comprises a voltage divider, an operational amplifier, and a negative feedback resistor connected between every two capacitors. The circuit is configured to monitor the voltage in each of the capacitors and, if the voltage in one of the capacitors is higher than the other, the circuit transfers energy from the higher charged capacitor to the lower charged capacitor until the capacitors are balanced. A current limiting resistor can be included for limiting the output current of the operational amplifier to a safe value and for providing feedback information regarding the health of the capacitor. An additional gain stage can also be included for increasing the output current of the operational amplifier for banks of large charge storage devices such as capacitors.

Claims30

Dependent claims

A charge balancing circuit for providing charge balancing for at least two charge storage devices connected in series, the at least two charge storage devices capable of being charged by a supply voltage, the charge balancing circuit comprising:

a voltage divider for equally dividing the supply voltage across the at least two charge storage devices;
an operational amplifier having inputs and an output, the operational amplifier being connected at its output between each at least two charge storage devices and the operational amplifier being connected to the voltage divider such that the voltage divider provides a voltage to an input of the operational amplifier;
a negative, feedback resistor for providing feedback regarding a stored voltage in each of the at least two charge storage devices to an input of the operational amplifier;
wherein the operational amplifier is configured to produce an output current when the stored voltage of a first of the at least two charge storage devices is higher than the stored voltage of a second of the at least two charge storage devices, the output current causing energy stored in the first charge storage device to be transferred to the second charge storage device until the at least two charge storage devices are balanced.

1 more element

A charge balancing circuit for providing charge balancing for n charge storage devices connected in series, wherein n is greater than or equal to 2, the n charge storage devices capable of being charged by a supply voltage, the charge balancing circuit comprising:

n-1 voltage dividers for equally dividing the supply voltage across the n charge storage devices;
n-1 operational amplifiers having inputs and an output, each operational amplifier being connected at its output between two charge storage devices and each operational amplifier being connected to one of the n-1 voltage dividers such that each voltage divider provides a voltage to an input of an operational amplifier,
n-1 negative feedback resistors, each negative feedback resistor connected to one of the n-1 operational amplifiers, the n-1 negative feedback resistors for providing feedback regarding stored voltage in the n charge storage devices to an input of one of the n-1 operational amplifiers;
wherein each operational amplifier is configured to produce an output current when the stored voltage at a first of the two charge storage devices to which it is connected is higher then the stored voltage at a second of the two charge storage devices to which it is connected, the output current causing energy stored in the first charge storage device to be transferred to the second charge storage device until the two charge storage devices are balanced.

1 more element

Dependencies are inferred from the claim text.

Charge balancing circuit

Life of this patent

Charge balancing circuit

Life of this patent

Abstract

Claims30