# US 6,611,117 B1 · Drive circuit for a brushless DC motor > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 6,611,117 B1 - Document ID: US6611117B1 - Status: Granted - Kind: B1 - Application number: 09/556,717 - Filed: 2000-04-21 - Granted: 2003-08-26 - Earliest claimed: 2000-04-21 - Assignees: Minebea Co., Ltd. - Inventors: Eric A. Hardt - Web page: https://patentgrep.com/patent/US6611117B1 ## CPC - H02P 6/16: Circuit arrangements for detecting position - H02P 6/12: Monitoring commutation; Providing indication of commutation failure - H02P 6/20: Arrangements for starting (H02P6/08 takes precedence) - H02P 29/032: Preventing damage to the motor, e.g. setting individual current limits for different drive conditions - Y10S 388/904: Stored velocity profile - H02P: CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS - Y10S: TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS ## Abstract A drive circuit for a brushless DC motor controls at least one of a number of possible operation features of the motor. The drive circuit includes a driver stage for providing a current for a stator coil and varies which of the number of possible operation features of the motor are controlled. The operation features of the motor include inrush current limit control, PWM speed control, analog speed control, detecting a locked rotor condition, setting an alarm following detection of the locked rotor condition, restarting the motor following the locked rotor condition, detecting a low speed condition, and setting an alarm following detection of the low speed condition. Some of the operation features of the motor utilize at least one parameter that defines the desired operation of the feature. The drive circuit further varies the parameters of the operation features without changing the physical configuration of the brushless DC motor. ## Claims ### Claim 1 A drive circuit for a brushless DC motor that controls at least one operation feature of said motor, said at least one feature utilizing at least one parameter that defines the desired operation of said feature, said drive circuit comprising: a driver stage being configured to provide a current to a stator coil; means coupled to said driver stage for varying said at least one parameter and for comparing said at least one parameter with a signal generated by the operation of said motor; a software means controlling said means coupled to said driver stage; a microcontroller comprising said software means; and a sensor coupled to said microcontroller; wherein the means coupled to said driver stage further comprises a delay means for providing a delay, said delay corresponding to at least one parameter which can be varied by instructions from said software means; and wherein said sensor controls said delay means. ### Claim 2 (depends on 1) The drive circuit according to claim 1, wherein said means for varying includes input means for inputting said at least one parameter. ### Claim 3 (depends on 1) The drive circuit according to claim 1, wherein said means for varying said parameters comprises a microcontroller that executes software program instructions to control said features. ### Claim 4 (depends on 1) The drive circuit according to claim 1, wherein: said feature comprises limiting inrush current drawn by said brushless DC motor upon start-up of said motor. ### Claim 5 (depends on 4) The drive circuit according to claim 4, wherein said parameter comprises a threshold reference value for said inrush current. ### Claim 6 (depends on 4) The drive circuit according to claim 4, wherein said parameter comprises a compare value from which a voltage representing said inrush current is subtracted. ### Claim 7 (depends on 1) The drive circuit according to claim 1, wherein said feature comprises speed control of said brushless DC motor using an analog voltage. ### Claim 8 (depends on 7) The drive circuit according to claim 7, wherein said parameter comprises a threshold reference value for the speed of said motor. ### Claim 9 (depends on 1) The drive circuit according to claim 1, wherein said feature comprises generating an alarm signal. ### Claim 10 (depends on 9) The drive circuit according to claim 9, wherein said parameter comprises a threshold level for the speed of said DC motor. ### Claim 11 (depends on 9) The drive circuit according to claim 9, wherein said parameter further comprises a value stored in a counter. ### Claim 12 (depends on 9) The drive circuit according to claim 9, wherein said parameter further comprises a value indicating a time for generating said alarm. ### Claim 13 (depends on 1) The drive circuit according to claim 1, wherein said feature comprises determining a locked rotor condition. ### Claim 14 (depends on 13) The drive circuit according to claim 13, wherein said parameter comprises a value stored in a counter. ### Claim 15 (depends on 1) The drive circuit according to claim 1, wherein said feature comprises generating an alarm in response to the detection of a locked rotor condition. ### Claim 16 (depends on 15) The drive circuit according to claim 15, wherein said parameter comprises a value stored in a counter. ### Claim 17 (depends on 1) The drive circuit according to claim 1, wherein said feature comprises restarting said motor following the detection of a locked rotor condition. ### Claim 18 (depends on 17) The drive circuit according to claim 17, wherein said parameter comprises a value stored in a counter. ### Claim 19 A drive circuit for a brushless DC motor that controls at least one of a number of possible operation features of said motor, said drive circuit comprising: a driver stage being configured to provide a current for a stator coil; means for varying which of said number of possible operation features of said motor are controlled and for controlling said varied feature in response to a signal generated by the operation of said motor; a software means controlling said means for varying; a microcontroller comprising said software means; and a sensor coupled to said microcontroller; wherein the means for varying further comprises a delay means for providing a delay, said delay corresponding to at least one parameter which can be varied by instructions from said software means; and wherein said sensor controls said delay means. ### Claim 20 (depends on 19) The drive circuit according to claim 19, wherein said at least one of a number of possible operation features of said motor comprises speed control of said motor using a pulse-width modulated signal. ### Claim 21 (depends on 19) The drive circuit according to claim 19, wherein said at least one of a number of possible operation features of said motor comprises speed control of said motor using an analog voltage. ### Claim 22 (depends on 19) The drive circuit according to claim 19, wherein said at least one of a number of possible operation features of said motor comprises limiting inrush current drawn by said motor upon start-up of said motor. ### Claim 23 (depends on 19) The drive circuit according to claim 19, wherein said at least one of a number of possible operation features of said motor comprises generating an alarm signal if the speed of said motor is below a threshold level. ### Claim 24 (depends on 19) The drive circuit according to claim 19, wherein said at least one of a number of possible operation features of said motor comprises generating an alarm in response to the detection of a locked rotor condition. ### Claim 25 (depends on 19) The drive circuit according to claim 19, wherein said at least one of a number of possible operation features of said motor comprises restarting said motor following the detection of a locked rotor condition. ### Claim 26 A fan, comprising: a brushless DC motor; a drive circuit for said brushless DC motor, said drive circuit controlling at least one operation feature of said motor, said at least one feature utilizing at least one parameter that defines the desired operation of said feature; said driving circuit comprising: a driver being configured to provide a current to a stator coil; means coupled to said driver stage for varying said at least one parameter and for comparing said at least one parameter with a signal generated by the operation of said motor; a software means controlling said means coupled to said driver stage; a microcontroller comprising said software means; and a sensor coupled to said microcontroller; wherein the means coupled to said driver stage further comprises a delay means for providing a delay, said delay corresponding to at least one parameter which can be varied by instructions from said software means; and wherein said sensor controls said delay means. ### Claim 27 (depends on 26) The fan according to claim 26, wherein said means for varying said parameters comprises a microcontroller that executes software program instructions to control said features. ### Claim 28 (depends on 26) The fan according to claim 26, wherein said feature comprises limiting inrush current drawn by said brushless DC motor upon start-up of said motor. ### Claim 29 (depends on 28) The fan according to claim 28, wherein said parameter comprises a threshold reference value for said inrush current. ### Claim 30 (depends on 28) The fan according to claim 28, wherein said parameter comprises a compare value from which a voltage representing said inrush current is subtracted. ### Claim 31 (depends on 26) The fan according to claim 26, wherein said feature comprises speed control of said brushless DC motor using an analog voltage. ### Claim 32 (depends on 31) The fan according to claim 31, wherein said parameter comprises a threshold reference value for the speed of said motor. ### Claim 33 (depends on 26) The fan according to claim 26, wherein said feature comprises generating an alarm signal. ### Claim 34 (depends on 33) The fan according to claim 33, wherein said parameter comprises a threshold level for the speed of said DC motor. ### Claim 35 (depends on 33) The fan according to claim 33, wherein said parameter further comprises a value indicating a time for generating said alarm. ### Claim 36 (depends on 26) The fan according to claim 26, wherein said feature comprises determining a locked rotor condition. ### Claim 37 (depends on 26) The fan according to claim 26, wherein said feature comprises restarting said motor following the detection of a locked rotor condition. ### Claim 38 A fan comprising: a brushless DC motor; a drive circuit for said brushless DC motor that controls at least one of a number of possible operation features of said motor; said drive circuit comprising: a driver stage for providing a current for a stator coil; means for varying which of said number of possible operation features of said motor are controlled and for controlling said varied feature in response to a signal generated by the operation of said motor; a software means controlling said means for varying; a microcontroller comprising said software means; and a sensor coupled to said microcontroller; wherein the means for varying further comprises a delay means for providing a delay, said delay corresponding to at least one parameter which can be varied by instructions from said software means; and wherein said sensor controls said delay means. ### Claim 39 (depends on 38) The fan according to claim 38, wherein said at least one of a number of possible operation features of said motor comprises speed control of said motor using a pulse-width modulated signal. ### Claim 40 (depends on 38) The fan according to claim 38, wherein said at least one of a number of possible operation features of said motor comprises speed control of said motor using an analog voltage. ### Claim 41 (depends on 38) The fan according to claim 38, wherein said at least one of a number of possible operation features of said motor comprises limiting inrush current drawn by said motor upon start-up of said motor. ### Claim 42 (depends on 38) The fan according to claim 38, wherein said at least one of a number of possible operation features of said motor comprises generating an alarm signal if the speed of said motor is below a threshold level. ### Claim 43 (depends on 38) The fan according to claim 38, wherein said at least one of a number of possible operation features of said motor comprises generating an alarm in response to the detection of a locked rotor condition. ### Claim 44 (depends on 38) The fan according to claim 38, wherein said at least one of a number of possible operation features of said motor comprises restarting said motor following the detection of a locked rotor condition.