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US 2011/0031974 A1Published application
Method and System to Measure Series-Connected Cell Voltages using a Flying Capacitor
AssigneeEnerdel, Inc.
InventorsRonald H. Jaeger, Chad Hartzog
Life of this patent
Estimating the term…
Abstract
A method and system for measuring voltage of individual cells connected in series includes a pair of busses connectable to the cells and a flying capacitor connectable to the busses. The capacitor stores the charge of one of the cells such that an analog-to-digital converter (ADC) connected to the capacitor may process an accurate representation of the voltage of the cell being measured. In order to prevent electrical interference with the capacitor and the ADC, the charge on the busses is reduced prior to measurement by the ADC
Claims20
1:
- A method of measuring voltage of individual cells in a plurality of cells connected in series, said method comprising:
- electrically connecting one of the cells to a capacitor via a plurality of busses disposed between the cells and the capacitor;
- charging the capacitor;
- electrically disconnecting the capacitor from the busses in response to an elapse of the predetermined charge time;
- and
- reducing the charge on the busses in response to the electrical disconnection of the capacitor from the busses.
3 more elements
2:
- A method as set forth in claim 1 further comprising the step of measuring the voltage of the capacitor in response to the reduction of the charge on the busses to generate a digital voltage signal.
3:
- A method as set forth in claim 2 further comprising the step of reading the digital voltage signal by a controller.
4:
- A method as set forth in claim 1 wherein said step of reducing the charge on the busses is further defined as electrically connecting the busses to the cells with the lowest potential in response to the electrical disconnection of the capacitor from the busses.
5:
- A method as set forth in claim 1 wherein said step of reducing the charge on the busses is further defined as discharging the busses by electrically connecting the busses to ground in response to the electrical disconnection of the capacitor from the busses.
6:
- A system for measuring voltage of individual cells in a plurality of cells connected in series, said system comprising:
- a plurality of cell switches for electrical connection to the plurality of cells wherein each cell switch includes a first side and a second side with said first side of each cell switch electrically connectable to a positive terminal of one of the cells;
- a first bus electrically connected to said second side of every other cell switch;
- a second bus electrically connected to said second side of each cell switch not connected to said first bus;
- a capacitor for storing a charge of at least one of the cells wherein said capacitor includes a pair of terminals;
- a first bus switch electrically connected between said first bus and said capacitor for connecting at least one of the cells to said capacitor;
- a second bus switch electrically connected between said second bus and said capacitor for connecting at least one of the cells to said capacitor;
- a ground switch connected at one terminal to one of the terminals of the capacitor and at an other terminal to ground, said ground switch being configured to move between an open and a closed state under the control of a controller;
- and
- a first bus ground switch electrically connected between said first bus and ground and a second bus ground switch electrically connected between said second bus and ground.
7 more elements
7:
- A system as set forth in claim 6 further comprising an analog-to-digital converter (ADC) in electrical communication with said capacitor for receiving a voltage from said capacitor and converting the voltage into digital voltage data.
8:
- A system as set forth in claim 7 further comprising a controller in communication with said ADC for controlling said switches and receiving the digital voltage data provided by the ADC.
9:
- A system as set forth in claim 6 wherein said first bus switch is further defined as a first bus positive switch electrically connected between said first bus and a positive terminal of said capacitor and a first bus negative switch electrically connected between said first bus and a negative terminal of said capacitor.
10:
- A system as set forth in claim 8 wherein said second bus switch is further defined as a second bus positive switch electrically connected between said second bus and said positive terminal of said capacitor and a second bus negative switch electrically connected between said second bus and said negative terminal of said capacitor.
11:
- The method of claim 1 wherein the charging the capacitor step includes charging the capacitor for a predetermined charge time.
12:
- The method of claim 1 wherein the charging the capacitor step includes charging the capacitor to a charge state.
13:
- The method of claim 12 wherein the charging the capacitor step includes charging the capacitor to a charge state corresponding to the charge of one of the individual cells of the plurality of cells.
14:
- A method of measuring voltage of individual cells in a plurality of cells connected in series, said method comprising:
- electrically connecting one of the cells to a capacitor via a plurality of busses disposed between the cells and the capacitor;
- charging the capacitor;
- electrically disconnecting the capacitor from the busses in response to an elapse of the predetermined charge time;
- and
- reducing the charge on the busses by configuring switches utilizing a microprocessor in response to the electrical disconnection of the capacitor from the busses.
3 more elements
15:
- A method as set forth in claim 14 further comprising the step of measuring the voltage of the capacitor in response to the reduction of the charge on the busses to generate a digital voltage signal.
16:
- A method as set forth in claim 14 further comprising the step of reading the digital voltage signal by a controller.
17:
- A method as set forth in claim 14 wherein said step of reducing the charge on the busses is further defined as electrically connecting the busses to the cells with the lowest potential by configuring switches utilizing a microprocessor in response to the electrical disconnection of the capacitor from the busses.
18:
- A method as set forth in claim 14 wherein said step of reducing the charge on the busses is further defined as discharging the busses by electrically connecting the busses to ground in response to the electrical disconnection of the capacitor from the busses.
19:
- The method of claim 14 wherein the charging the capacitor step includes charging the capacitor for a predetermined charge time.
20:
- The method of claim 14 wherein the charging the capacitor step includes charging the capacitor to a charge state corresponding to the charge of one of the individual cells of the plurality of cells.