Patent Document

CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a continuation of U.S. patent application Ser. No. 11/159,948, filed Jun. 23, 2005, which claims priority to U.S. patent application Ser. No. 10/426,589 filed on Apr. 30, 2003 (now U.S. Pat. No. 7,102,303). The disclosures of the above applications are incorporated herein by reference. 
     
    
     FIELD 
       [0002]    The disclosure relates generally to systems and methods for controlling the operation of a motor. More specifically, the disclosure relates to a generic motor control module suitable for use with any of a variety of motors in any of a variety of motor applications. 
       BACKGROUND 
       [0003]    Typically, motors are controlled by dedicated analog or digital circuitry configured to control a specific motor in a specific application. For example, one dedicated circuit would be required to control a specific motor utilized in a power saw application, while another dedicated circuit would be required to control a different motor utilized in a drill application. Or further yet, one dedicated circuit would be required to control the motor utilized in a power saw application, while a different circuit would be required to utilize the same motor in a table saw application. Normally, each dedicated analog or digital control circuit would be constructed of different components. These components would typically have differing values and/or control software in order to create a unique operational characteristic profile for each motor and each specific motor application. 
         [0004]    The requirement of different dedicated control circuitry for different motors and different applications greatly increases manufacturing, engineering design, parts, inventory and labor costs. This is because, up until the present time, no one ‘generic’ or ‘universal’ control circuit or module was available that could be easily tailored to meet the operational needs of different types of applications (e.g. drills, saws, grinders, etc.). Thus, there has existed a need for a single control circuit or module that can easily be tailored to control and optimize performance of a given one of a plurality of differing motors in a given one of a plurality of differing motor applications that require different operational characteristics. 
       BRIEF SUMMARY 
       [0005]    The present disclosure, in one aspect, relates to a method for controlling a plurality of different motors used in a corresponding plurality of power tool applications requiring different operational characteristics. The method may comprise using a single universal control module to store a generic, non-application-specific control algorithm, where the generic, non-application-specific control algorithm has at least one programmable constant. The programmable constant is selected to transform the generic, non-application-specific control algorithm into an application-specific control algorithm. The programmable constant represents a function parameter relating to a specific functionality of a specific, selected motor used in a specific, selected motor application to implement a phase control over the specific, selected motor. 
         [0006]    In another aspect the present disclosure relates to a method for controlling a plurality of different motors used in a corresponding plurality of power tool applications requiring different operational characteristics. The method may comprise: providing a controller in communication with a memory to form a universal control module for a specific, selected power tool. A generic, non-application-specific control algorithm may be implemented in a software program, wherein the software program is stored in the memory. The generic, non-application-specific control algorithm may have at least one programmable constant that is programmable during manufacture of the specific, selected power tool. The programmable constant may be selected to transform the generic, non-application-specific control algorithm into an application-specific control algorithm. The programmable constant may thus represent a function parameter relating to a specific functionality of a specific, selected motor used in a specific, selected motor application. This tailors the non-application-specific control algorithm for use with a required operating parameter of the specific, selected motor used in the specific, selected power tool. 
         [0007]    In still another aspect the present disclosure relates to a motor control module adapted to universally control any of a plurality of different motors utilized in a plurality of differing implementations. The motor control module may comprise a first memory device adapted to store a generic control algorithm and at least one programmable variable utilized during execution of the generic control algorithm. A second memory device may be used that is adapted to store at least one programmable constant that represents a function parameter relating to a specific functionality of a specific, selected motor used in a specific, selected motor application. A processor may be used that is adapted to execute the generic control algorithm implementing the programmable variable and the programmable constant to transform the generic control algorithm from a non-tool-specific format into a tool-specific format. The tool-specific format may be specifically suited for implementing a phase control over operation of the specific, selected motor used in the specific, selected motor application. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]    The present disclosure will become more fully understood from the detailed description and accompanying drawings, wherein; 
           [0009]      FIG. 1  is a simplified circuit diagram of a generic motor control module, in accordance with one embodiment of the present disclosure; 
           [0010]      FIG. 2  is a flow chart illustrating the general operation of the generic motor control module in an AC implementation, as shown in  FIG. 1 ; 
           [0011]      FIG. 3  is a simplified circuit diagram of the generic motor control module  10  as utilized in a DC implementation, wherein the motor  14  is a DC motor; and 
           [0012]      FIG. 4  is a flow chart illustrating the general operation of the generic motor control module in a DC implementation, shown in  FIG. 3 . 
       
    
    
     DETAILED DESCRIPTION 
       [0013]      FIG. 1  is a simplified circuit diagram of a generic motor control module  10 , in accordance with one embodiment of the present disclosure. The generic motor control module  10  is connectable to a motor  14  that can be any one of a plurality of motors used in any one of a plurality of applications. The motor  14  can be an AC motor, as illustrated in  FIG. 1  or a DC motor as illustrated in  FIG. 3 . The generic motor control module  10  is also referred to herein as the universal control module  10  because it is universally applicable such that it is capable of controlling any of the plurality of motors, such as motor  14 , in any of the plurality of motor applications or implementations. More specifically, the generic motor control module  10  is capable of controlling motors of differing size, ratings and/or types, wherein the motors can be utilized in any of a plurality of applications or implementations without altering components, component values, and/or hard coded control software. Preferably, the generic motor control module  10  is a digital control module that includes a digital control circuit, generally indicated at  18 . 
         [0014]    For example, the generic motor control module  10  can be used to control the motor of a heavy duty half-inch drill that has a high gear ratio and generates a high degree of torque, or to control the motor of a quarter-inch drill that has a relatively low gear ratio and generates only a small degree of torque. Similarly, the generic motor control module  10  can be utilized to control a motor used in a plurality of applications. For example, if a specific model of motor were used in both a power saw application and a drill press application, each with different operational parameters, the generic motor control module  10  can be used to control the motor in both the power saw and the drill press without the need to change any electrical components, component values, or to alter control software associated with the module  10 . For simplicity, the generic motor control module  10  will be referred to hereinafter as simply the motor control module  10 . 
         [0015]    In an AC implementation, as shown in  FIG. 1 , the motor control module  10  is connectable to an AC power source, via the power cord (not shown), at an AC mains node  20   a  and a neutral node  20   b . The control circuit  18  of the motor control module  10  includes a power supply  22  that supplies power to a controller  26 , e.g. a microcontroller. The controller  26  includes a processor  30 , e.g. a microprocessor, programmed to control an electronic valve  34 , such as a triac, a field effect transistor (FET), an insulated gate bipolar transistor (IGBT), a silicon-controlled rectifier (SCR), or various voltage and/or current control devices. The controller  26  can be any suitable controller or microcontroller. One microcontroller especially well suited for use with control circuit  18  is an ATtiny26 microcontroller commercially available from ATMEL, Inc. of San Jose, Calif. To control operation of the motor  14 , the controller  26  controls the amount of current, and therefore voltage, applied to the motor  14  by controlling the operation of the electronic valve  34 . 
         [0016]    The control circuit  18  further includes a shunt resistor  38  and a voltage divider circuit  42  comprised of resistors  46 ,  48 ,  50  and clamping diodes  52  and  54 . The controller  26  includes an amplifier  56  used to amplify the voltage across the shunt resistor  38  used by the controller  26  to measure the current flowing through the electronic valve  34  and the motor  14 . The voltage divider circuit  42  is coupled via a circuit line  62  to the controller  26 . The resistors  46 ,  48  and  50  divide the AC source voltage to a voltage level usable by the controller  26 , and the clamping diodes  52  and  54  protect the controller  26  from damage if a voltage spike occurs in the AC source voltage. The controller  26  senses an AC zero crossing by measuring the divided voltage from the AC power source via the voltage divider circuit  42 . Alternatively, the controller  26  can sense an AC zero crossing by monitoring a digital signal provided by a subsystem, wherein the digital signal would represent a zero crossing of the AC voltage. The control circuit  18  also includes a pair of pull-up resistors  58  and  60  used to condition the voltage input at a ‘port  1 ’ and a ‘port  2 ’ of the controller  26 . 
         [0017]    Generally, the motor control module  10  controls the operation of the motor  14  by switching the motor current on and off at periodic intervals in relation to the zero crossing of the AC current or voltage waveform, via the controller  26  and control signals applied to a control input  34   a  of the electronic valve  34 . These periodic intervals are caused to occur in synchronism with the AC waveform and are measured in terms of a conduction angle, measured as a number of degrees. The conduction angle determines the point within the AC waveform at which the electronic valve  34  is fired, i.e. turned on, thereby delivering electrical energy to the motor  14 . More specifically, the conduction angle determines the point at which the electronic valve  34  is fired within a selected period of the AC waveform for which operation of the electronic valve  34  is based, for example, a half-cycle of the AC waveform. The electronic valve  34  turns off at the conclusion of the selected period. Thus, the conduction angle is measured from the point of firing of the electronic valve  34  to the point of extinguishing at the end of the selected period. 
         [0018]    The point at which the electronic valve is fired is also referred to in the art, and will alternatively be referred to herein, as the firing angle of the electronic valve  34 . The firing angle is measured from the beginning of the selected period to the point within the selected period at which the electronic valve  34  is fired. Numerically, the conduction angle and the firing angle are complements of one another. Generally, the conduction angle and firing angle are measured in units of degrees, but could also be measured in radians, or in unitless fractions of the selected period. 
         [0019]    For example, a conduction angle of 180° per half cycle of the AC cycle corresponds to a condition of full conduction, in which electronic valve  34  is fired such that the entire, uninterrupted alternating current is applied to the motor  14 . That is, the electronic valve  34  is fired such that current flows through the electronic valve  34  for the entire half cycle of the AC input signal. Similarly, a 90° conduction angle corresponds to developing the supply voltage across the motor  14  commencing in the middle of a given half cycle, and thus the electronic valve  34  is fired so that approximately half of the available energy is delivered to the motor. Conduction angles below 90° correspond to firing of the electronic valve  34  later in a given half cycle so that even lesser quantities of energy are delivered to the motor  14 . 
         [0020]    The motor control module  10  controls the operation of the motor  14  when a motor control switch  64 , e.g. a tool On/Off switch, is placed in a closed (i.e. ‘On’) position, thereby allowing current to flow through the motor  14 . Although motor control switch  64  is illustrated as being located between the node  20   a  and the motor  14 , alternatively, the motor control switch  64  can be located between the node  20   a  and the AC mains. In one embodiment, the control circuit  18  determines a firing angle solution for the electronic valve  34  for each half cycle of the AC line voltage. Alternatively, the control circuit  18  could determine the firing angle solution for each full cycle, each one and a half cycle, each two cycles, or any other predetermined periodic interval of the AC line voltage signal based on multiples of the half cycle. Although the present disclosure will be described herein as determining the firing angle solution based on a half cycle, it should be understood that the determination of the firing angle solution could be based on any multiple of the half cycle and remain within the scope of the present disclosure. 
         [0021]    To determine the firing angle solution for each half cycle such that the motor  14  will operate in a desired manner, various pertinent inputs, i.e. motor operating criterion, are measured during operation of the motor  14 . The various pertinent inputs are referred to herein as “Dynamicisms” and include, but are not limited to, such things as a closed loop dial, an open loop dial, an amount of current flowing through the motor  14  during operation, the voltage across the motor  14  during operation, an amount of torque provided by the motor  14 , and a speed of the motor  14 . For example, a first input  58   a  could be a closed loop dial signal, or a tachometer signal or any other dynamicism signal. Likewise, a second input  58   b  could be a motor speed signal, or an open loop dial signal or any other dynamicism signal. Dynamicisms include any motor operational value or parameter that has an effect on the calculation of the firing angle solution. As the dynamicisms change during operation, the firing angle solution for each subsequent half cycle, or other periodic interval based on half cycles, will also change. 
         [0022]    To generate a timing solution for the electronic valve  34 , i.e. the timing and duration for which the electronic valve  34  is turned on, the processor  30  executes a universal generic control algorithm stored in a memory device  66  included in the controller  26 . More specifically, the firing angle solution for each half cycle, or multiple thereof, of the AC line during operation of the motor  14 , the processor  30  executes a universal generic firing angle control algorithm. Alternatively, the memory device  66  could be included in the motor control module  10  external to the controller  26 . In various embodiments the memory device  66  is a functionally non-volatile, non-alterable memory device. For example, memory device  66  can be a read only memory (ROM) device, a Flash Memory device or a one time programmable (OTP) device. In one embodiment, the generic firing angle algorithm is hard-coded in the memory device  66  during manufacturing of the motor control module  10 . That is, the generic algorithm is stored in non-volatile memory device  66  as part of the process for manufacturing the motor control module  10  and can not be altered or modified once it is stored in the memory device  66 . Thus, the generic algorithm is applicable to determine the firing angle solution for any of a plurality of motor applications in which any of a plurality of motors, such as motor  14 , are controlled by the motor control module  10 . More specifically, the generic algorithm determines the firing angle solution for any motor  14  in which the motor control module  10  is installed, such that the motor  14  operates according to parameters specifically required for the particular motor application. 
         [0023]    In various alternative embodiments the generic algorithm can be stored in alterable memory that allows data to be stored, read and altered such as flash memory, erasable programmable read-only memory (EPROM) or electrically erasable programmable read-only memory (EEPROM). 
         [0024]    The processor  30  executes the generic algorithm utilizing the dynamicisms as inputs, thereby determining a firing angle solution specific to the particular motor  14  and the specific motor application. Generally, the generic algorithm can be expressed by the following equation: 
         [0000]      Firing angle solution= f (dynamicisms) 
         [0000]    It should be understood that the notation ‘f( )’ means ‘a function of ( )’, where the contents of the parentheses are the argument of the function f. 
         [0025]    For example, in one embodiment, the generic algorithm could be more specifically expressed by the following equation. 
         [0000]      Firing angle solution= f ( f (switch position)+(f(dial setting 1)+ f (dial setting 2)+ f (current)+ f (voltage)+ f (tachometer)+ . . .  f (dynamicism  n )+ K )+ M;    
         [0000]    where ‘switch position’ refers to the position of the motor control switch  64 , ‘dial setting  1  ’ refers to closed loop desired speed, ‘dial setting  2  ’ refers to open loop firing angle clamp, ‘current’ refers to the amount of current flowing through the motor  14 , ‘voltage’ refers to a voltage value across the motor  14 , ‘tachometer’ refers to a tachometric period or rate of rotational speed of the motor, and K and M are offsets or constants to bias the firing angle into the correct working range of operation for the particular implementation of the motor  14 . The tachometer period is the time period that is directly proportional to the inverse of the speed of the motor  14 . The motor control switch  64  controls the operational status of the motor  14 . That is, if the motor control switch  64  is in an open position, the motor  14  is in an ‘Off’ operational status, while if the motor control switch  64  is in a closed position, the motor  14  is in an ‘On’ operational status. 
         [0026]    The controller  26  samples the dynamicisms using appropriate sensors or sensing circuits (not shown) for each dynamicism and utilizes the processor  30  to execute the generic algorithm to determine the proper firing angle solution for the electronic valve  34  for each half cycle of the AC line voltage. Additionally, the generic algorithm utilizes at least one motor function coefficient stored in a memory device  68  to determine the firing angle solution such that the motor  14  functions in accordance with motor operational parameters specific to the particular application of the motor  14 . Generally, the motor operational parameters of a given application will require the use of more than one function coefficient in the execution of the generic algorithm. In various embodiments, the motor function coefficient is a soft-coded function coefficient and the memory device  68  is an alterable memory device that allows data to be stored, read and altered such as flash memory, erasable programmable read-only memory (EPROM) or electrically erasable programmable read-only memory (EEPROM). Alternatively, the memory device  68  can be a functionally non-volatile, non-alterable memory device, such as a read only memory (ROM) device, a Flash Memory device or a one time programmable (OTP) device. 
         [0027]    In one embodiment, the function coefficient(s) are stored in the alterable memory device  68  subsequent to the manufacturing of the motor control module  10  and subsequent to the motor control module  10  being implemented in a particular application. For example, if the control module  10  is utilized to control the motor  14  of a hammer drill, the function coefficient(s) specific to the motor operational parameters of the hammer drill are not stored in the alterable memory device  68  until after the hammer drill has been assembled including the motor control module  10 . Thus, after the exemplary hammer drill is assembled including the motor control module  10 , an external device (not shown) capable of communicating with the controller  26  is used to program (i.e. store) the function coefficient(s) in the alterable memory device  68 . The external device communicates the function coefficient(s) to the alterable memory device  68  over any suitable means for data transmission. For example, the function coefficient(s) can be transmitted from the external device to the alterable memory device  68  over the power cord of the tool, e.g. the hammer drill. The external device can be any computer-based device capable of transmitting data, such as a laptop computer, a hand-held computer or any other programming device. Alternatively, the module  10  could be programmed after its manufacture but before being implemented in a particular application. 
         [0028]    A further derivation of the generic algorithm incorporating the function coefficient(s) can be expressed by summing the products of the dynamicism(s) and associated function coefficient(s), as illustrated by the following equation. 
         [0000]      Firing angle solution= f ((switch position* C   0 )+((dial setting 1* C   1 )+(dial setting 2* C   2 )+(current* C   3 )+(voltage* C   4 )+(tachometer* C   5 )+ . . . (dynamicism  n*C   n )+ C   n+1 )+ C   n+2 ); 
         [0000]    where the value for ‘switch position’ equals one (1) if the motor control switch  64  is in a closed (i.e. ‘On’) position and zero (0) if the motor control switch  64  is in an open (i.e. ‘Off’) position. Additionally, C 0 , C 1 , C 2 , C 3 , C 4 , C 5  . . . C n , C n+1 , C n+2  are function coefficients specific to a particular application of the motor  14 , so that the motor  14  operates in accordance with desired motor operational parameters of the particular application. 
         [0029]    Thus, if a particular dynamicism is to have no impact on the firing angle solution for the electronic valve  34  in a given application, the function coefficient of that particular dynamicism would be zero (0). For example, if the motor control module  10  is implemented in an application where open loop control is desirable, C 2 , C 3 , C 4  and C 5 , in the above generic algorithm, would be zero (0). However, if the motor control module  10  is implemented in an application where closed loop control is desirable, but there is no tachometer utilized in the application, then C 1 , C 2 , C 3  and C 4  would have values calculated to operate the motor  14  in accordance with desired motor operational parameters, and C 5  would be zero (0). 
         [0030]    Therefore, in one embodiment, the processor  30  executes the generic algorithm during each half cycle of the AC power source, implementing the function coefficient(s), stored in alterable memory device  68 , as a constant value(s) in the algorithm, and utilizing the dynamicism(s) as an input variable(s) to determine the firing angle solution for the electronic valve  34 , for each given half cycle. Alternatively, the controller  26  could execute the generic algorithm based on multiples of the half cycle, as opposed to executing the generic algorithm during each half cycle. In this instance each firing angle solution calculated will be used to fire the electronic valve  34  for two or more consecutive half cycles. That is, although the electronic valve  34  will be fired during each half cycle based on the firing angle solution generated by execution of the generic algorithm, the generic algorithm will not be executed during each half cycle. 
         [0031]    Since the dynamicism(s) is a variable, the calculated firing angle solution will change during operation of the motor  14  due to variations in load requirements for the motor  14  during operation and changes in function settings of the device in which the motor  14  is installed. For example, if the load requirement of the motor  14  changes during operation, the dynamicism for the current and/or the voltage being used by the motor  14  will change leading to a change in the firing angle solution to compensate for the change in power needed by the motor  14 . Additionally, if a user changes the speed setting on a power drill, the associated dynamicism(s) will change, thereby altering the firing angle solution generated by the generic algorithm. 
         [0032]    Although, in the various embodiments described herein, the motor control module  10  has been described to execute the generic algorithm shown above, it should be appreciated that the particular algorithm described is exemplary only. As such the description of the exemplary algorithm does not exhaust all possible algorithms for use in implementing the motor control module  10 , in accordance with the present disclosure. Accordingly, changes in the algorithm described above may be made by those skilled in the art without departing from the scope of the disclosure. For example, the generic algorithm could utilize a look-up table as a transfer function to generate firing angle solutions, as described below. 
         [0033]      FIG. 2  is flow chart  100  illustrating the general operation of the motor control module  10  (shown in  FIG. 1 ), in accordance with one preferred AC embodiment of the present disclosure. In a practical application of the motor control module  10 , on each given half cycle, or multiple thereof, the controller  26  initially synchronizes with the zero cross of the AC voltage source to acquire a reference for firing of the electronic valve  34 , as indicated at step  104 . Next, the controller  26  utilizes the processor  30  to sample any one, or all, dynamicism(s), as indicated at step  108 . The processor  30  then retrieves the soft-coded function coefficient(s) from the alterable memory device  68 , as indicated at step  112 . After retrieving the function coefficient(s), the processor  30  executes the generic algorithm, incorporating the dynamicism(s) and the function coefficient(s), to determine the firing angle solution for the electronic valve for the given predetermined periodic interval, e.g. a half cycle, as indicated at step  116 . The processor  30  then fires the electronic valve  34  for the given periodic interval at the calculated firing angle, thereby operating the motor  14  in accordance with motor operational parameters of the specific application of the motor  14 , as indicated at step  120 . 
         [0034]    Although the generic algorithm has been described above to be hard-coded in memory device  66 , in an alternate embodiment, the generic algorithm is soft-coded in an alterable memory device, such as memory device  68 . Thus, in this embodiment, the generic algorithm can be programmed into the motor control module  10  subsequent to the manufacturing of the motor control module  10 . Additionally, by storing the generic algorithm in an alterable memory device, the generic algorithm could be modified using an external programming device, any time it is desirable to do so. 
         [0035]    In an alternate embodiment, the firing angle solution, or duty cycle solution, described below with reference to  FIG. 3 , is determined using at least one look-up table stored in either the alterable or non-alterable memory devices  68  and  66 . That is, look-up table(s) are used as transfer functions to control any of the plurality of motors, such as motor  14 , in any one of the plurality of applications. 
         [0036]    An address, or index, of the look-up table(s) is any one of, or any combination of, the dynamicisms suitably scaled or modified to accommodate the range of possible look-up table addresses, i.e. inputs. That is, the dynamicisms are not generally suitable to be used directly as indexes to the look-up table(s). The dynamicisms must be adjusted to accommodate the input range of the addresses to the look-up table(s). For example, the electronic valve  34  has firing angle range of 0° to 180° for normal sinusoidal AC power. Therefore, the dynamicisms must be modified or scaled to generate firing angle solutions within the range of 0° to 180°. Similarly, the motor  14  may have some specified speed range, e.g. 0 to 5000 revolutions per minute (rpm). Therefore, the dynamicisms must be modified or scaled to generate firing angle solutions that will operate the motor  14  within the specified speed range. Thus, the firing angle solution is still determined as a function of the dynamicisms, generally expressed by the equation: 
         [0000]      Firing angle solution= f (dynamicisms). 
         [0037]    For example, on one embodiment, the generic algorithm could be more specifically expressed by the following equation. 
         [0000]      Look-up table address= K   N *dynamicism N+K   2 *dynamicism2+ K   1 *dynamicism1+ K   0 ; 
         [0000]    where K is an offset or constant to bias the firing angle into the correct working range of operation for the particular implementation of the motor  14 . 
         [0038]    The address generated by the generic algorithm is input to the look-up table(s) and thereby utilized to output a corresponding firing angle solution stored in the look-up table(s). The content of the look-up table comprises a plurality of predetermined firing angles for the electronic valve  34 . Thus, based on the input address, the corresponding firing angle contained in the look-up table is output to control the timing of the electronic valve  34 . 
         [0039]    The content of the look-up table(s) is predetermined based upon empirical data. In a preferred implementation, the empirical data used to determine the content of the look-up table(s) is the same data used to determine the generic firing angle control algorithm and all necessary constants C 0  to C n+2 , as described above. The look-up table(s) can be permanently programmed into the non-alterable memory device  66  or the alterable memory device  68  prior to, or subsequent to, the control module  10  being implemented into the specific tool. For example, 130, or 256, or 512 firing angle solutions for the electronic valve  34  could be stored in the look-up table(s) to be accessed by 130, or 256, or 512 addresses, or indexes, computed from the dynamicisms. 
         [0040]    In a DC implementation wherein the motor  14  is a DC motor, as described below, the look-up table(s) are utilized to determine a pulse width modulated (PWM) duty cycle, or some other suitable control function for the motor  14 . The address, or index, of the look-up table(s), as generated by the generic algorithm, is any one of, or any combination of, the dynamicisms suitably scaled or modified to accommodate the range of possible look-up table addresses, i.e. inputs. For example, the electronic valve  134  (shown in  FIG. 3 ) has a duty cycle of 0% to  100  for normal DC power. Therefore, the dynamicisms must be modified or scaled to generate duty cycle solutions within the range of 0% to 100%. Similarly, the motor  14  may have some specified speed range, e.g. 0 to 5000 revolutions per minute (rpm). Therefore, the dynamicisms must be modified or scaled to generate duty cycle solutions that will operate the motor  14  within the specified speed range. 
         [0041]    Thus, the duty cycle solution is also determined as a function of the dynamicisms, generally expressed by the equation: 
         [0000]      Duty cycle solution= f (dynamicisms). 
         [0042]    For example, on one embodiment, the generic algorithm could be more specifically expressed by the following equation. 
         [0000]      Look-up table address= K   N *dynamicism N+K   2 *dynamicism2+ K   1 *dynamicism1+ K   0 ; 
         [0000]    where K is an offset or constant to bias the duty cycle into the correct working range of operation for the particular implementation of the motor  14 . 
         [0043]    The address generated by the generic algorithm is input to the look-up table(s) and thereby utilized to output a corresponding duty cycle solution stored in the look-up table(s). The content, i.e. output, of the look-up table is the duty cycle solution, or other control function, for the electronic valve  34 . As in the AC implementation, the look-up table(s) can be permanently programmed into the non-alterable memory device  66  or the alterable memory device  68  prior to, or subsequent to, the control module  10  being implemented into the specific tool. For example, 130, or 256, or 512 duty cycle, or other control function, solutions for the electronic valve  34  could be stored in the look-up table(s) to be accessed by 130, or 256, or 512 addresses, or indexes, computed from the dynamicisms. 
         [0044]    The look-up tables can be multidimensional wherein the scaled or modified dynamicisms are used as X-coordinates, i.e. inputs, of a first look-up table and the Y-coordinate, i.e. output, of the first look-up table is then used as an X-coordinate, i.e. input, of a second look-up table. The Y-coordinate, i.e. output, of the second look-up table then yields the operational timing of the electronic valve  34 , e.g. the firing angle or duty cycle solution. 
         [0045]    It is envisioned that the use of a look-up table(s) as transfer functions could provide greater flexibility, significantly greater speed, and conserve space in the applicable memory device  66  or  68  than the use of the mathematical algorithm described above. More particularly, the computational burden would be removed from the real-time operation of the controller  26  having been transferred to the prior development of look-up table(s). The controller  26  need only look-up the correct firing angle or duty cycle, based on one or more of the plurality of dynamicisms, rather than compute the correct firing angle solution every full cycle, or multiple thereof. 
         [0046]    In another embodiment, non-motor function tool operational parameters, e.g. tool features, can be programmed into the control module  10  using soft-coded coefficients. Such tool operational parameters control different tool operating features for different tool applications. For example, the tool operational coefficients can control such tool operating features as ‘no-volt’ tool operation, electronic clutch operation, thermal overload protection and brush wear indication. The tool features can be enabled and disabled within the particular tool, via execution of the generic control algorithm incorporating the soft-coded tool operational coefficients or utilizing the look-up table(s), as described above. Alternatively, the tool features can be enabled and disabled within the particular tool utilizing state diagrams, wherein the tool features can be sequenced between an operational state and a non-operational state depending on conditions defined by soft-coded tool operational coefficients. 
         [0047]    Furthermore, the tool features can be enabled and disabled within the particular tool to control the operation features of the tool without affecting the motor performance, i.e. function, coefficients. The tool operational coefficients can be stored in the alterable memory device  68  or the non-alterable memory device  66  subsequent to the manufacturing of the motor control module  10  and can be either permanently resident within the control module  10  or uploaded as needed. More specifically, the tool operational coefficients can be programmed into the non-alterable memory device  66  prior to the control module  10  being installed into the tool or uploaded to the alterable memory device  68 , via an external communication device, subsequent to the control module  10  being implemented in the tool. The external communication device could be any computer-based device capable of transmitting data, such as a laptop computer, a hand-held computer or any other programming device. 
         [0048]      FIG. 3  is a simplified circuit diagram of a generic motor control module  100  that is effectively the same as the motor control module  10 , described above, utilized in a DC implementation. For clarity and simplicity, components of the motor control module  100  that are substantially the same as components of the motor control module  10  are identified in  FIG. 3  using the reference numerals of  FIG. 1  incremented by 100. The motor control module  100  is connectable to a DC power source  190 , such as a battery, at DC terminals  120   a  and  120   b . The control circuit  118  includes a power supply  122  that supplies power to a controller  126 , e.g. a microcontroller. The controller  126  includes a processor  130 , e.g. a microprocessor, programmed to control an electronic valve  134 , such as a bipolar transistor, a field effect transistor (FET), an insulated gate bipolar transistor (IGBT), or various voltage and/or current control devices. To control operation of the motor  114 , the controller  126  controls the amount of current, and therefore voltage, applied to the motor  114  by controlling the operation of the electronic valve  134 . 
         [0049]    The control circuit  118  additionally includes a shunt resistor  138 . The controller  126  includes an amplifier  156  used to amplify the voltage across the shunt resistor  138  used by the controller  126  to measure the current flowing through the electronic valve  134  and the motor  114 . The control circuit  118  also includes a pair of pull-up resistors  158  and  160  used to condition the voltage input at a ‘port  1 ’ and a ‘port  2 ’ of the controller  126 . 
         [0050]    Generally, the motor control module  100  controls the operation of the motor  114  by switching the motor current on and off at periodic intervals, via the controller  126  and control signals applied to a control input  134   a  of the electronic valve  134 . These periodic intervals are based on a pulse width modulated (PWM) duty cycle calculated by the controller  126 . The duty cycle stipulates the time and duration that the electronic valve  134  is fired, thereby delivering electrical energy to the motor  114 . 
         [0051]    The motor control module  100  controls the operation of the motor  114  when a motor control switch  164 , e.g. a tool On/Off switch, is placed in a closed (i.e. ‘On’) position, thereby allowing current to flow through the motor  114 . Although motor control switch  164  is illustrated as being located between the node  120   a  and the motor  14 , alternatively, the motor control switch  164  can be located between the node  120   a  and the DC power source  190 . To determine the duty cycle, the dynamicisms are measured during operation of the motor  114 . As described above, the dynamicisms include, but are not limited to, such things as a closed loop dial, an open loop dial, an amount of current flowing through the motor  114  during operation, the voltage across the motor  114  during operation, an amount of torque provided by the motor  114 , and a speed of the motor  114 . For example, a first input  158   a  could be a closed loop dial signal, or a tachometer signal or any other dynamicism signal. Likewise, a second input  158   b  could be a motor speed signal, or an open loop dial signal or any other dynamicism signal. Dynamicisms include any motor operational value or parameter that has an effect on the calculation of the duty cycle for the electronic valve  134 . As the dynamicisms change during operation, the duty cycle will also change. 
         [0052]    To generate a timing solution for the electronic valve  134 , i.e. the timing and duration for which the electronic valve  134  is turned on, the processor  130  executes a universal generic control algorithm stored in a functionally non-volatile memory device  166  included in the controller  126 . More specifically, to generate the duty cycle for the electronic valve  134  the processor  130  executes a universal generic duty cycle control algorithm. For example, memory device  166  could be a read only memory (ROM) device, a Flash Memory device or a one time programmable (OTP) device. Alternatively, the memory device  166  could be included in the motor control module  100  external to the controller  126 . 
         [0053]    In one embodiment, the generic duty cycle algorithm is hard-coded in the memory device  166  during manufacturing of the motor control module  100 . That is, the generic algorithm is stored in non-volatile memory device  166  as part of the process for manufacturing the motor control module  100  and can not be altered or modified once it is stored in the memory device  166 . Thus, the generic algorithm is applicable to determine a timing solution, i.e. a duty cycle solution, for the electronic valve  134  for any of a plurality of motor applications in which any of a plurality of motors, such as motor  114 , are controlled by the motor control module  100 . More specifically, the generic algorithm determines a duty cycle solution for any motor  114  in which the motor control module  100  is installed, such that the motor  114  operates according to parameters specifically required for the particular motor application. 
         [0054]    The processor  130  executes the generic algorithm utilizing the dynamicisms as inputs, thereby determining a duty cycle solution specific to the particular motor  114  and the specific motor application. Generally, the generic algorithm can be expressed by the following equation: 
         [0000]      Duty cycle solution= f (dynamicisms) 
         [0055]    For example, in one embodiment, the generic algorithm could be more specifically expressed by the following equation. 
         [0000]      Duty cycle solution= f ( f (switch position)+( f (dial setting 1)+ f (dial setting 2)+ f (current)+ f (voltage)+ f (tachometer)+ . . .  f (dynamicism  n )+ K )+ M;    
         [0000]    where ‘switch position’ refers to the position of the motor control switch  64 , ‘dial setting  1 ’ refers to closed loop desired speed, ‘dial setting  2 ’ refers to open loop firing angle clamp, ‘current’ refers to the amount of current flowing through the motor  114 , ‘voltage’ refers to a voltage value across the motor  114 , and ‘tachometer’ refers to a tachometric period or rate of rotational speed of the motor. The motor control switch  164  controls the operational status of the motor  114 . That is, if the motor control switch  164  is in an open position, the motor  114  is in an ‘Off’ operational status, while if the motor control switch  164  is in a closed position, the motor  114  is in an ‘On’ operational status. 
         [0056]    The controller  126  samples the dynamicisms using appropriate sensors or sensing circuits (not shown) for each dynamicism and utilizes the processor  130  to execute the generic algorithm to determine the proper duty cycle solution for the electronic valve  134 . Additionally, the generic algorithm utilizes at least one soft-coded function coefficient stored in a non-volatile alterable memory device  168  to determine the duty cycle solution such that the motor  114  functions in accordance with motor operational parameters specific to the particular application of the motor  114 . Generally, the motor operational parameters of a given application will require the use of more than one function coefficient in the execution of the generic algorithm. Alterable memory device  168  can be any suitable memory device that allows data to be stored, read and altered such as flash memory, erasable programmable read-only memory (EPROM) or electrically erasable programmable read-only memory (EEPROM). 
         [0057]    In one embodiment, the function coefficient(s) are stored in the alterable memory device  168  subsequent to the manufacturing of the motor control module  100  and subsequent to the motor control module  100  being implemented in a particular application. An external device (not shown) capable of communicating with the controller  126  is used to program (i.e. store) the function coefficient(s) in the alterable memory device  168 . The external device communicates the function coefficient(s) to the alterable memory device  168  over any suitable means for data transmission. For example, the function coefficient(s) can be transmitted from the external device to the alterable memory device  168  over battery terminals, e.g. terminals  20   a  and  20   b , of the associated power tool. Alternatively, the module  100  could be programmed after its manufacture but before being implemented in a particular application. 
         [0058]    A further derivation of the generic algorithm incorporating the function coefficient(s) can be expressed by summing the products of the dynamicism(s) and associated function coefficient(s), as illustrated by the following equation. 
         [0000]      Firing angle solution= f ((switch position* C   0 )+((dial setting 1* C   1 )+(dial setting 2* C   2 )+(current* C   3 )+(voltage* C   4 )+(tachometer* C   5 )+ . . . (dynamicism  n*C   n )+ C   n+1 )+ C   n+2 ); 
         [0000]    where the value for ‘switch position’ equals one (1) if the motor control switch  64  is in a closed (i.e. ‘On’) position and zero (0) if the motor control switch  64  is in an open (i.e. ‘Off’) position. Additionally, C 0 , C 1 , C 2 , C 3 , C 4 , C 5  . . . C n , C n+1 , C n+2  are function coefficients specific to a particular application of the motor  114 , so that the motor  114  operates in accordance with desired motor operational parameters of the particular application. 
         [0059]    Thus, the processor  130  executes the generic algorithm, implementing the function coefficient(s) stored in alterable memory device  168 , as a constant value(s) in the algorithm, and utilizing the dynamicism(s) as an input variable(s) to determine the duty cycle solution for the electronic valve  134 . Since the dynamicism(s) is a variable, the calculated duty cycle solution will change during operation of the motor  114  due to variations in load requirements for the motor  114  and changes in function settings of the device in which the motor  114  is installed. For example, if the load requirement of the motor  114  changes during operation, the dynamicism for the current and/or the voltage being used by the motor  114  will change leading to a change in the duty cycle solution to compensate for the change in power needed by the motor  114 . Additionally, if a user changes the speed setting on a power drill, the associated dynamicism(s) will change, thereby altering the duty cycle solution generated by the generic algorithm. 
         [0060]    Although, in the various embodiments described herein, the motor control module  100  has been described to execute the generic algorithms shown above, it should be appreciated that the particular algorithm described is exemplary only. As such the description of the exemplary algorithm does not exhaust all possible algorithms for use in implementing the motor control module  100 , in accordance with the present disclosure. Accordingly, changes in the algorithm described above may be made by those skilled in the art without departing from the scope of the disclosure. For example, the generic algorithm could utilize a look-up table as a transfer function to generate duty cycle solutions, as described above. Additionally, although the DC implementation of the control module  118  has been described above utilizing a PWM duty cycle to determine the timing of the electronic valve  134 , it should be understood that any suitable discrete control function could be utilized and remain with the scope of the disclosure. 
         [0061]    Additionally, although various embodiments described herein disclose a controller, e.g. a microcontroller, implementation of the motor control module  10 , it should be understood that the motor control module  10  may also utilize other forms of digital circuitry. That is, the control circuit  18  of the motor control module  10  can include any electrical and semiconductor devices suitable to sample the dynamicism(s) and execute the generic algorithm, as described above. For example, control circuit  18  could be a discrete digital logic integrated circuit, or an application specific integrated circuit (ASIC), or a combination of digital and analog circuitry, or any combination thereof. 
         [0062]      FIG. 4  is flow chart  200  illustrating the general operation of the motor control module  100  (shown in  FIG. 2 ), in accordance with one preferred DC embodiment of the present disclosure. In a practical application of the motor control module  100 , the controller  126  utilizes the processor  130  to sample any one, or all, dynamicism(s), as indicated at step  204 . The processor  130  then retrieves the soft-coded function coefficient(s) from the alterable memory device  168 , as indicated at step  108 . After retrieving the function coefficient(s), the processor  130  executes the generic algorithm, incorporating the dynamicism(s) and the function coefficient(s), to determine the duty cycle solution for the electronic valve  134 , as indicated at step  112 . The processor  130  then fires the electronic valve  134  in accordance with the duty cycle solution, thereby operating the motor  114  in accordance with motor operational parameters of the specific application of the motor  114 , as indicated at step  116 . 
         [0063]    While the disclosure has been described in terms of various specific embodiments, those skilled in the art will recognize that the disclosure can be practiced with modification within the spirit and scope of the claims.

Technology Category: 5