Controlled power fade for battery powered devices

• US 9,413,088 B2
• Filed: 01/23/2015
• Issued: 08/09/2016
• Est. Priority Date: 04/07/2010
• Status: Active Grant

• Current Assignee: Black & Decker Incorporated (Stanley Black & Decker, Inc.)
• Original Assignee: Black & Decker Incorporated (Stanley Black & Decker, Inc.)
• Inventors: Brotto, Daniele C., Forster, Michael K., Leh, Jason K., Lin, Wing W.
• Primary Examiner(s): Ro, Bentsu
• Assistant Examiner(s): Dinh, Thai
• Application Number:
  US14/603,977
• Publication Number:
  US 20150137715A1
• Time in Patent Office: 564 Days
• Field of Search: 318/139, 318/430, 318/443, 318/454, 318/455, 318/478, 318/479, 318/490, 318/599, 320/116, 320/118, 320/132, 320/134, 320/145, 324/429, 324/431, 324/433
• US Class Current: 1/1
• CPC Class Codes: B25F 5/00 Details or components of portable power-driven tools not particularly related to the operations performed and not otherwise provided for
• CPC Class Codes: B25F 5/02 Construction of casings, bodies or handles B25F5/006, B25F5/008 take precedence
• CPC Class Codes: B25F 5/021 with guiding devices guiding devices for hand tools on stands or supports B25H1/0078
• CPC Class Codes: G01R 31/3646 for indicating electrical conditions or variables, e.g. visual or audible indicators
• CPC Class Codes: G01R 31/374 with means for correcting the measurement for temperature or ageing
• CPC Class Codes: G01R 31/3835 involving only voltage measurements
• CPC Class Codes: G01R 31/385 Arrangements for measuring battery or accumulator variables for monitoring G01R31/382
• CPC Class Codes: H01H 2009/065 Battery operated hand tools in which the battery and the switch are directly connected
• CPC Class Codes: H01H 9/061 enclosing a continuously variable impedance
• CPC Class Codes: H01M 10/441 for several batteries or cells simultaneously or sequentially
• CPC Class Codes: H01M 10/448 End of discharge regulating measures
• CPC Class Codes: H01M 2010/4271 Battery management systems including electronic circuits, e.g. control of current or voltage to keep battery in healthy state, cell balancing
• CPC Class Codes: H01M 2010/4278 Systems for data transfer from batteries, e.g. transfer of battery parameters to a controller, data transferred between battery controller and main controller
• CPC Class Codes: H01M 2220/30 Batteries in portable systems, e.g. mobile phone, laptop
• CPC Class Codes: H01M 50/569 Constructional details of current conducting connections for detecting conditions inside cells or batteries, e.g. details of voltage sensing terminals battery terminal connectors with integrated measuring arrangements G01R31/364
• CPC Class Codes: H01R 12/7005 Guiding, mounting, polarizing or locking means; Extractors for printed circuit boards H05K
• CPC Class Codes: H01R 13/112 forked sockets having two legs
• CPC Class Codes: H02J 7/00034 Charger exchanging data with an electronic device, i.e. telephone, whose internal battery is under charge
• CPC Class Codes: H02J 7/00041 in response to measured battery parameters, e.g. voltage, current or temperature profile
• CPC Class Codes: H02J 7/0013 acting upon several batteries simultaneously or sequentially H02J7/1423 takes precedence
• CPC Class Codes: H02J 7/0019 : using switched or multiplexed charge circuits
• CPC Class Codes: H02J 7/0025 : Sequential battery discharge in systems with a plurality of batteries
• CPC Class Codes: H02J 7/0029 : with safety or protection devices or circuits
• CPC Class Codes: H02J 7/00306 : Overdischarge protection
• CPC Class Codes: H02J 7/0031 : using battery or load disconnect circuits H02J9/002 takes precedence
• CPC Class Codes: H02J 7/0045 : concerning the insertion or the connection of the batteries
• CPC Class Codes: H02J 7/0048 : Detection of remaining charge capacity or state of charge [SOC]
• CPC Class Codes: H02J 7/0063 : with circuits adapted for supplying loads from the battery
• CPC Class Codes: H02J 7/00714 : in response to battery charging or discharging current
• CPC Class Codes: H02J 7/007182 : in response to battery voltage
• CPC Class Codes: H02P 3/08 : for stopping or slowing a dc motor
• CPC Class Codes: H02P 31/00 : Arrangements for regulating or controlling electric motors not provided for in groups H02P1/00 - H02P5/00, H02P7/00 or H02P21/00 - H02P29/00
• CPC Class Codes: H02P 7/285 : controlling armature supply only
• CPC Class Codes: H02P 7/29 : using pulse modulation
• CPC Class Codes: Y02E 60/10 : Energy storage using batteries
• CPC Class Codes: Y02P 70/50 : Manufacturing or production processes characterised by the final manufactured product

Abstract

A method is provided for operating a power tool having a motor powered by a battery. The method includes: delivering power from the battery to the motor in accordance with an operator input; detecting a condition of the power tool indicating a shutdown of the power is imminent; and fading the power delivered from the battery to the motor, in response to the detected condition, through the use of a controller residing in the power tool.

Claims

1. A method for operating a power tool having a trigger switch and a motor powered by a battery pack, comprising:

setting the duty cycle of a pulse width modulated control signal in accordance with a position of the trigger switch;

delivering power from the battery pack to the motor in accordance with the control signal;

monitoring a parameter indicative of tool operation while power is delivered from the battery pack to the motor using a controller residing in the power tool;

detecting a condition of the parameter indicating a shutdown of the power is imminent; and

fading the power delivered from the battery to the motor, in response to the detected condition, using the controller, wherein the fading step comprises;

computing a value of the duty cycle as a function of a value of the parameter, and

setting the duty cycle of the control signal to the computed value of the duty cycle when the computed value of the duty cycle is less than the duty cycle set in accordance with position of the trigger switch, and retaining the duty cycle set in accordance with the position of the trigger switch when the computed value of the duty cycle is more than the duty cycle set in accordance with the position of the trigger switch.

2. The method of claim 1 wherein fading of the power delivered is by an amount that is computed as a function of a value of the parameter.

3. The method of claim 1 wherein fading of the power delivered further comprises decreasing the power delivered as a function of the value of the parameter, where the function is at least one of linear, step, exponential or polynomial.

4. The method of claim 1 wherein the parameter is voltage of the battery, comprising:

initiating fading of the power delivered when the battery voltage falls below a voltage fade threshold and decreasing the power delivered linearly as a function of the battery voltage until the battery voltage falls below a voltage cutoff threshold.

5. The method of claim 1 wherein the parameter is temperature in the power tool, the method comprising:

initiating fading of the power delivered when the temperature exceeds a temperature fade threshold and decreasing the power delivered linearly as a function of the temperature until the temperature exceeds a temperature cutoff threshold.

6. The method of claim 1 wherein the parameter is temperature in the battery pack, the method comprising:

fading of the power delivered when the temperature exceeds a temperature fade threshold and decreasing the power delivered linearly as a function of the temperature until the temperature exceeds a temperature cutoff threshold.

7. The method of claim 6, wherein the battery pack includes a positive terminal, a negative terminal, a temperature sense terminal, battery cells coupled to the positive and negative terminals, and a temperature sensor electrically coupled to the positive terminal.

8. A power tool system comprising:

a tool assembly having a motor;

a battery pack that selectively couples to the tool assembly and operates to provide power to the motor;

a trigger switch disposed on the tool assembly;

a discharge control module that is in data communication with the trigger switch and regulates power provided to the motor in accordance with a position of the trigger switch by adjusting a duty cycle of pulse width modulated control signal of a switch disposed in series with the motor, wherein the discharge control module is configured to monitor a parameter indicative of tool operation while power is delivered from the battery pack to the motor and fade the power delivered from the battery to the motor by adjusting the duty cycle of the control signal by an amount that is computed as a function of a value of the parameter,

wherein the discharge control module sets the duty cycle to a value computed as a function of a value of the parameter when the computed value of the duty cycle is less than the duty cycle set in accordance with position of the trigger switch, and retains the duty cycle set in accordance with the position of the trigger switch when the computed value of the duty cycle is more than the duty cycle set in accordance with the position of the trigger switch.

9. The power tool system of claim 8 wherein the discharge control module fades the power delivered by decreasing the power delivered as a function of the value of the parameter, where the function is at least one of linear, step, exponential or polynomial.

10. The power tool system of claim 8, wherein the discharge control module monitors voltage of the battery, initiates fading of the power delivered when the battery voltage falls below a voltage fade threshold and decreases the power delivered linearly as a function of the battery voltage until the battery voltage falls below a voltage cutoff threshold.

11. The power tool system of claim 8, further comprising a temperature sensor disposed in the tool assembly, wherein the discharge control module is configured to receive a temperature measure from the temperature sensor, initiate fading of the power delivered when the temperature exceeds a temperature fade threshold and decrease the power delivered linearly as a function of the temperature until the temperature exceeds a temperature cutoff threshold.

12. The power tool system of claim 8, further comprising a temperature sensor disposed in the battery pack and in data communication with the discharge control module, wherein the discharge control module is configured to monitor temperature in the battery pack, initiate fading of the power delivered when the temperature exceeds a temperature fade threshold and decrease the power delivered linearly as a function of the temperature until the temperature exceeds a temperature cutoff threshold.

13. The power tool of claim 12, wherein the battery pack includes a positive terminal, a negative terminal, a temperature sense terminal, battery cells coupled to the positive and negative terminals, and a temperature sensor electrically coupled to the positive terminal.

14. The power tool of claim 8, wherein the switch is disposed in series with battery cells of the battery pack.

15. The power tool system of claim 8, wherein the discharge control module resides in the tool assembly.

16. The power tool system of claim 8, wherein the discharge control module resides in the battery pack.

17. A power tool system comprising:

a tool assembly having a motor;

a battery pack having a plurality of battery cells that selectively couples to the tool assembly via a positive terminal and a negative terminal to provide electric power to the motor;

a trigger switch disposed on the tool assembly; and

a discharge control module within the tool assembly that controls power delivered from the battery to the motor in accordance with a position of the trigger switch, wherein the discharge control module is electrically coupled to the battery pack to measure voltage of the battery cells while the tool is being operated by a user by interrupting current flow from the battery pack to the motor momentarily via a power switch while the trigger switch is being pulled by the user and measuring voltage of the battery in an unloaded condition while current flow is interrupted, the discharge control module being further configured to compare the unloaded voltage measure to a voltage cutoff threshold, and resume current flow from the battery to the motor when the unloaded voltage measure exceeds the voltage cutoff threshold.

18. The power tool of claim 17, wherein the discharge control module is configured to terminate current discharge of the battery via the switch when the unloaded voltage measure is less than the voltage cutoff threshold.

19. The power tool of claim 17, wherein the discharge control module is configured to interrupt current via the power switch for a period of time on the order of milliseconds to measure voltage of the battery in an unloaded condition.

20. The power tool of claim 17, wherein the discharge control module is configured to delay the voltage measure of the battery in an unloaded condition.

21. The power tool of claim 17, wherein the discharge control module is configured to measure voltage of a single battery cell or a portion of the battery cells.

22. The power tool of claim 17, wherein the discharge control module is configured to interrupt current periodically via the switch to measure voltage of the battery in an unloaded condition while current is being drawn from the battery.

23. The power tool of claim 17, wherein the discharge control module is configured to fade the power delivered from the battery to the motor by an amount that is computed as a function of a value of the unloaded voltage measure.