Electric Tool Control Circuit

Abstract

An electric tool control circuit includes a central control module, a motor drive module, a motor, and a working parameter detection module. The working parameter detection module can detect and communicate a parameter to the central control module related to a load on the motor detected during running of the motor. The motor drive module is separately electrically connected to the motor by using first and second switch modules, and the motor drive module controls the first and second modules to be discontinuously on and off to thereby reduce variation of a speed of the motor caused by a variation of the load on the motor. The status of the first and second switch modules being on and off are always contrary. A related method is disclosed.

1 . An electric tool control circuit comprising:
 a motor;   a central control module, a motor drive module, a working parameter detection module, a first switch module, and a second switch module;   the central control module being electrically connected to the motor drive module, and the central control module controlling turn on and off of the motor drive module; and   the working parameter detection module being electrically connected to the motor and the central control module, the working parameter detection module detecting and communicating a parameter to the central control module, the parameter being related to a load on the motor detected during running of the motor, the motor drive module being electrically connected to the motor by a first switch module and a second switch module, the motor drive module controlling the first and second switch modules to be discontinuously on and off to thereby reduce variation of a speed of the motor caused by a variation of the load on the motor, the respective statuses of the first switch module and the second switch module being on and off are always contrary so that when the first switch module is on, the second switch module is off, and when the first switch module is off, the second switch module is on.   
     
     
         2 . The electric tool control circuit according to  claim 1 , wherein the first and second switch modules, the motor drive module and the motor are electrically connected to form a half-bridge driving circuit. 
     
     
         3 . The electric tool control circuit according to  claim 2 , wherein field effect transistors are used as the first and second switch modules. 
     
     
         4 . The electric tool control circuit according to  claim 1 , wherein the parameter detected by the working parameter detection module is at least one of a current of the motor, a voltage of the motor, a speed of the motor, and a temperature of the motor. 
     
     
         5 . The electric tool control circuit according to  claim 1 , wherein the protection module has a spike absorption module and a follow current module, which respectively form a circuit loop with the motor. 
     
     
         6 . The electric tool control circuit according to  claim 5 , wherein the spike absorption module includes a first spike absorption module and a second spike absorption module. 
     
     
         7 . The electric tool control circuit according to  claim 6 , wherein the first spike absorption module is a capacitor, the second spike absorption module is a schottky diode, and the follow current module is a diode. 
     
     
         8 . The electric tool control circuit according to  claim 1 , wherein the working parameter detection module has a current detection module which has a detection time inversely proportional to a magnitude of current value detected when the motor is loaded to increase rotation speed. 
     
     
         9 . The electric tool control circuit according to  claim 1 , wherein the working parameter detection module has a current detection module which has a detection time proportional to a magnitude of current value detected when the motor idling at high speed reduces speed. 
     
     
         10 . The electric tool control circuit according to  claim 1 , further including a protection module which can prevent a motor peripheral circuit from being damaged by motor clutter produced during running of the motor. 
     
     
         11 . A method of controlling a speed of a motor of a tool having a central control module, a motor drive module, a working parameter detection module, a first switch module, and a second switch module, the method including the steps of:
 controlling a turning on and a turning off of the motor drive module using the central control module;   detecting a parameter related to a load on the motor during running of the motor using the working parameter detection module, communicating the parameter detected to the central control unit using the working parameter detection module, the motor drive module being electrically connected to the motor by a first switch module and a second switch module; and   controlling the first and second switch modules using the motor drive module to be discontinuously on and off to thereby reduce variation of a speed of the motor caused by a variation of the load on the motor, the controlling step including setting respective on and off statuses of the first switch module and the second switch module to always be opposite so that when the first switch module is on, the second switch module is off, and when the first switch module is off, the second switch module is on.   
     
     
         12 . The method according to  claim 11 , wherein the first and second switch modules, the motor drive module and the motor are electrically connected to form a half-bridge driving circuit. 
     
     
         13 . The method according to  claim 12 , wherein field effect transistors are used as the first and second switch modules. 
     
     
         14 . The method according to  claim 11 , wherein detecting step includes detecting at least one of a current of the motor, a voltage of the motor, a speed of the motor, and a temperature of the motor. 
     
     
         15 . The method according to  claim 11 , wherein the protection module has a spike absorption module and a follow current module, which respectively form a circuit loop with the motor. 
     
     
         16 . The method according to  claim 15 , wherein the spike absorption module includes a first spike absorption module and a second spike absorption module. 
     
     
         17 . The method according to  claim 16 , wherein the first spike absorption module is a capacitor, the second spike absorption module is a schottky diode, and the follow current module is a diode. 
     
     
         18 . The method according to  claim 11 , wherein the working parameter detection module has a current detection module which has a detection time inversely proportional to a magnitude of current value detected when the motor is loaded to increase rotation speed. 
     
     
         19 . The method according to  claim 11 , wherein the working parameter detection module has a current detection module which has a detection time proportional to a magnitude of current value detected when the motor idling at high speed reduces speed. 
     
     
         20 . The method according to  claim 11 , further including a protection module which can prevent a motor peripheral circuit from being damaged by motor clutter produced during running of the motor.