System And Method To Divert Inductive Energy From Cells

Abstract

A power tool/battery pack combination includes an electric motor, one or more electrochemical cells, and a capacitive element. The electric motor is connected in series to a first switch. The series combination of the electric motor and the first switch is connected to a first terminal and a second terminal. The one or more electrochemical cells are connected across a third terminal and a fourth terminal. The third terminal and the fourth terminal are coupled respectively to the first terminal and the second terminal. The one or more electrochemical cells supply power to the electric motor via the first switch. The capacitive element includes one or more capacitors. The capacitive element is connected across the third terminal and the fourth terminal. The capacitive element is capable of storing inductive energy generated by the one or more electrochemical cells.

1 . A power tool and battery pack combination comprising:
 a power tool including an electric motor connected in series to a first switch, the series combination of the electric motor and the first switch connected to a first terminal and a second terminal; and   a battery pack including one or more electrochemical cells connected across a third terminal and a fourth terminal, the third terminal and the fourth terminal coupled respectively to the first terminal and the second terminal, wherein the one or more electrochemical cells supply power to the electric motor via the first switch; and a capacitive element including one or more capacitors, the capacitive element connected across the third terminal and the fourth terminal, the capacitive element capable of storing inductive energy generated by the one or more electrochemical cells.   
     
     
         2 . The combination of  claim 1  wherein the capacitive element prevents the inductive energy from being applied to the first switch in response to the motor being operated at varying speeds. 
     
     
         3 . The combination of  claim 1  wherein a value of the capacitive element depends on a voltage supplied by the one or more electrochemical cells and a chemical composition of the one or more electrochemical cells. 
     
     
         4 . The combination of  claim 1  wherein:
 the one or more electrochemical cells are connected in series, in parallel, or using a combination of series and parallel connections; and 
 the one or more capacitors are connected in series, in parallel, or using a combination of series and parallel connections. 
 
     
     
         5 . The combination of  claim 1  further comprising a fuse coupled to the one or more capacitors, wherein the fuse transforms into an open circuit when one of the one or more capacitors associated with the fuse malfunctions. 
     
     
         6 . The combination of  claim 1  further comprising:
 a second switch connected in series with the first switch, wherein the second switch has a higher power rating than the first switch; and 
 a controller to control the second switch, 
 wherein the controller opens the second switch to stop supply of power from the one or more electrochemical cells to the electric motor when a temperature, voltage, or current of the one or more electrochemical cells crosses a predetermined threshold. 
 
     
     
         7 . The combination of  claim 1  wherein:
 an inductance of the one or more electrochemical cells is a sum of inductances of each of the one or more electrochemical cells; and 
 a value of the inductance depends on a design of the one or more electrochemical cells. 
 
     
     
         8 . A battery pack for supplying power to a power tool, the battery pack comprising:
 a housing having a first terminal and a second terminal and configured to detachable couple to the power tool;   at least one electrochemical cell contained in the housing, a given electrochemical cell having a given shape and connected across the first terminal and the second terminal of the housing;   a compartment container contained in the housing, the container having a shape equivalent to the given electrochemical cell with dimensions equal to the given shape of the given electrochemical cell; and   two or more capacitors electrically coupled together and contained in the container, where the two or more capacitors are connected across the first terminal and the second terminal of the housing.   
     
     
         9 . The battery pack of  claim 8  wherein the two or more capacitors store inductive energy generated by the at least one electrochemical cell. 
     
     
         10 . The battery pack of  claim 8  wherein a value of the two or more capacitors depend on a voltage supplied by the at least one electrochemical cells and a chemical composition of the at least one electrochemical cells. 
     
     
         11 . The battery pack of  claim 8  wherein:
 there are at least two electrochemical cells and the at least two electrochemical cells are connected in series, in parallel, or using a combination of series and parallel connections; and 
 there are at least two capacitors and the at least two capacitors are connected in series, in parallel, or using a combination of series and parallel connections. 
 
     
     
         12 . The battery pack of  claim 8  further comprising a fuse coupled to the two or more capacitors, wherein the fuse transforms into an open circuit when one of the two or more capacitors associated with the fuse malfunctions. 
     
     
         13 . The battery pack of  claim 8  further comprising:
 a switch; and 
 a controller that opens the switch to stop supply of power from the at least one electrochemical cells to a load when a temperature, voltage, or current of the at least one electrochemical cells crosses a predetermined threshold. 
 
     
     
         14 . The battery pack of  claim 8  wherein:
 an inductance of the at least one electrochemical cells is a sum of inductances of each of the at least one electrochemical cells; and 
 a value of the inductance depends on a design of the at least one electrochemical cells. 
 
     
     
         15 . A battery pack for a power tool, the battery pack comprising:
 a capacitive element;   at least one electrochemical cell, the at least one electrochemical cell having a geometry; and   a plurality of compartments contained in a housing, each of the compartments having a geometry equivalent to the geometry of the at least one electrochemical cell,   wherein the capacitive element and the at least one electrochemical cell reside in respective compartments of the battery pack.   
     
     
         16 . The battery pack of  claim 15  wherein the capacitive element includes at least one capacitor, wherein the capacitive element is connected across a first terminal and a second terminal of the housing, and wherein the capacitive element stores inductive energy generated by the at least one electrochemical cell. 
     
     
         17 . A power tool and battery pack combination comprising:
 an electric motor arranged in a first housing, the first housing including a first terminal and a second terminal to receive power to drive the electric motor;   at least one electrochemical cell arranged in a second housing, the second housing including a third terminal and a fourth terminal coupled respectively to the first terminal and the second terminal of the first housing, the at least one electrochemical cell connected across the third terminal and the fourth terminal;   a first switch residing in the first housing, the first switch connecting the at least one electrochemical cell to the electric motor responsive to a first control signal;   a first controller residing in the first housing, the first controller generating the first control signal; and   a capacitive element residing in the second housing.   
     
     
         18 . The combination of  claim 17  wherein the capacitive element includes at least one capacitor, wherein the capacitive element is connected across the third terminal and the fourth terminal of the second housing, and wherein the capacitive element stores inductive energy generated by the at least one electrochemical cell thereby preventing the inductive energy from being applied to the first switch. 
     
     
         19 . The combination of  claim 17 , wherein:
 the at least one electrochemical cell has a geometry;   a plurality of compartments contained in the second housing, each of the plurality of compartments having a geometry equivalent to the geometry of the at least one electrochemical cell;   the capacitive element resides in a first one of the plurality of compartments; and   the at least one electrochemical cell resides in a second one of the plurality of compartments.   
     
     
         20 . The combination of  claim 17  wherein a value of the capacitive element depends on a voltage supplied by the one or more electrochemical cells and a chemical composition of the one or more electrochemical cells. 
     
     
         21 . The combination of  claim 17  wherein:
 there are at least two electrochemical cells and the at least two electrochemical cells are connected in series, in parallel, or using a combination of series and parallel connections; and 
 there are at least two capacitors and the at least two capacitors are connected in series, in parallel, or using a combination of series and parallel connections. 
 
     
     
         22 . The combination of  claim 17  further comprising a fuse coupled to one or more capacitors of the capacitive element, wherein the fuse transforms into an open circuit when one of the one or more capacitors associated with the fuse malfunctions. 
     
     
         23 . The combination of  claim 17  further comprising:
 a second switch residing in the second housing, wherein the second switch is connected in series with the first switch, wherein the second switch has a higher power rating than the first switch; and 
 a second controller residing in the second housing, the second controller generating a second control signal when a temperature, voltage, or current of the one or more electrochemical cells crosses a predetermined threshold, 
 wherein the second controller opens the second switch to stop supply of power from the one or more electrochemical cells to the electric motor based on the second control signal.