Abstract:
A vehicle window lift control system includes a window lift motor, a motor drive/control module, an inverter, a rotor position sensing unit, and an anti-pinch module. The window lift motor is a brushless direct current motor. The anti-pinch module detennines whether or not the vehicle window is in an anti-pinch area based on position feedback signals generated by a rotor position sensing unit that is inherently included in the brushless direct current motor. When the vehicle window is in the anti-pinch area, an obstacle judgment unit is initiated. When there is an obstacle, an anti-pinch instruction unit sends an anti-pinch instruction to the motor drive/control module, and the motor drive/control module drives the inverter according to the anti-pinch instruction to make the motor rotate reversely. The present vehicle window lift control system has the advantages of small size, low failure rate and low cost.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This non-provisional patent application claims priority under 35 U.S.C. §119(a) from Patent Application No. 201610116816.X filed in The People&#39;s Republic of China on Mar. 1, 2016. 
       FIELD OF THE INVENTION 
       [0002]    This invention relates to a vehicle window lift control system and its control method, and in particular to a vehicle window lift control system with an anti-pinch function and its control method. 
       BACKGROUND OF THE INVENTION 
       [0003]    Many cars are equipped with electric windows to facilitate opening and closing of the windows. Opening and closing of the electric windows are achieved through a vehicle window lift mechanism. The vehicle window lift mechanism typically includes a motor and an associated transmission assembly. However, traditionally, the motor for driving the vehicle window is usually a brushed motor including components such as a stator, a rotor, brushes, and the like, which leads to a relatively large motor size. In addition, as the motor operates, a commutator connected with the rotor and the brushes produce a mutual friction therebetween, which causes the brushes to be easily worn. Therefore, the electric vehicle windows utilizing the brushed motor have a high failure rate and short lifespan. In addition, current electric vehicle windows usually need to include an auto-lift system, and the electric vehicle windows including the auto-lift system need to have an anti-pinch function. Therefore, a switch-type Hall sensor needs to be installed to determine the position of the vehicle window, which greatly dilutes the cost advantages of utilizing the brushed motor. 
       SUMMARY OF THE INVENTION 
       [0004]    Accordingly, there is a need for a vehicle window lift control system having a relatively smaller size, lower failure rate and reasonable cost, and a vehicle window lift control method. 
         [0005]    A vehicle window lift control system for controlling lifting up or lowering down of a vehicle window includes a window lift motor, a motor drive/control module, an inverter, and a rotor position sensing unit. The window lift motor is a brushless direct current motor. The motor drive/control module is configured to drive the inverter to thereby control rotation of the window lift motor based on a rotor position feedback signal obtained by the rotor position sensing unit. The vehicle window lift control system further includes an anti-pinch module. The anti-pinch module includes a pulse counter, a count comparator, an obstacle judgment unit, and an anti-pinch instruction unit. The pulse counter is configured to record the number of pulses generated by the rotor position sensing unit during lifting up of the vehicle window. The count comparator is configured to compare the recorded number of the pulses against a preset threshold to determine whether or not the vehicle window is in an anti-pinch area. The obstacle judgment unit is initiated when it is determined that the vehicle window is in the anti-pinch area. When the obstacle judgment unit determines that there is an obstacle, the anti-pinch instruction unit sends an anti-pinch instruction to the motor drive/control module, and the motor drive/control module drives the inverter according to the anti-pinch instruction to make the motor rotate reversely. 
         [0006]    A vehicle window lift control method includes the steps of: providing a brushless direct current motor for driving a vehicle window to lift up or lower down; operating the brushless direct current motor according to an external command and a motor position feedback signal; determining whether or not the vehicle window is in an anti-pinch area according to the rotor position feedback signal; determining whether or not the lifting vehicle window meets an obstacle according a motor operating parameter when it is determined that the vehicle window is in the anti-pinch area; and controlling the motor to perform an anti-pinch operation when it is determined that the lifting vehicle window meets an obstacle. 
         [0007]    The vehicle window lift control system of the present invention utilizes the brushless direct current motor, and the anti-pinch operation is performed based on the position feedback signals generated by the rotor position sensing unit that is inherently included in the brushless direct current motor. Therefore, the present vehicle window lift control system has a smaller size, lower failure rate and reasonable cost. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]      FIG. 1  is a block diagram of a vehicle window lift control system according to one embodiment of the present invention. 
           [0009]      FIG. 2  is a block diagram of a vehicle window lift control system according to another embodiment of the present invention. 
           [0010]      FIG. 3  is a circuit diagram of the inverter of  FIG. 1 . 
           [0011]      FIG. 4  is a circuit diagram of the inventor of  FIG. 1  according to another embodiment. 
           [0012]      FIG. 5  is a flow chart of a vehicle window lift control method according to one embodiment. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0013]    The present invention will now be described further, by way of example only, with reference to the accompanying drawings. 
         [0014]    Referring to  FIG. 1 , a vehicle window lift control system of the present invention is used to control a vehicle window  80  to lift up or lower down. The vehicle window lift control system includes a window lift motor  10 , a motor drive/control module  20 , an inverter  30 , a rotor position sensing unit  40 , and an anti-pinch module  50 . 
         [0015]    The window lift motor  10  is a three-phase or single-phase brushless direct current motor. The window lift motor  10  is connected to the vehicle window  80  through a transmission assembly including a gearbox, traction cables, and the like, such that power outputted from a rotary shaft of the window lift motor  10  is transmitted to the vehicle window  80  to form a traction force for driving the vehicle window  80  to lift up or lower down. 
         [0016]    The motor drive/control module  20  is configured to receive and execute an external command, and have the functions of data processing and driving the inverter  30 . The motor drive/control module  20  includes a command receiving unit  21 , a data processing unit  23 , and a driving unit  25 . The command receiving unit  21  receives an external command, such as an instruction of lifting up, lowering down or stopping the vehicle window that is inputted through a button or a trigger. The data processing unit  23  performs data processing according to the received command to obtain a corresponding motor control signal. The driving unit  25  obtains a regular driving signal according to the motor control signal and drives the inverter  30  to supply or cut off power to various windings of the window lift motor  10 , thereby starting the motor  10  in a desired direction or stopping the motor  10 . 
         [0017]    Since the window lift motor  10  is a brushless direct current motor, in order to ensure continuous operation of the window lift motor  10 , the rotor position sensing unit  40  is required to detect a position of the motor rotor, and upon the motor rotor  50  rotating over a preset position, the motor drive/control module  20  drives the inverter  30  to make the motor  10  run continuous. Specifically, the data processing unit  23  of the motor drive/control module  20  is connected to the rotor position sensing unit  40  to receive a position feedback signal from the rotor position sensing unit  40 . The data processing unit  23  generates commutation instruction according to the position feedback signal, and the driving unit  25  drives the inverter  30  to perform proper commutation, thereby ensuring continuous rotation of the window lift motor  10  and hence achieving the control of automatic lifting up or lowering down of the vehicle window  80 . The rotor position sensing unit  40  includes one or more switch-type Hall sensors. Each of the switch-type Hall sensors generates a continuous square wave signal as the motor operates. 
         [0018]    In one embodiment, the motor drive/control module  20  further includes a rotation direction judgment unit  27  to judge a motor actual rotating direction and judge whether the motor actual rotating direction is consistent with the control command received by the command receiving unit  21 , and generate a failure signal when the motor actual rotating direction is inconsistent with the control command It is noted that, when the rotation direction judgment unit  27  is included, the rotor position sensing unit  40  includes at least two switch-type Hall sensors, and the rotation direction judgment unit  27  judges the motor rotating direction according to a sequence of two square wave signals generated by the two switch-type Hall sensors. 
         [0019]    Specifically, when the window lift motor  10  is a three-phase brushless direct current motor, the rotor position sensing unit  40  includes three switch-type Hall sensors. The three switch-type Hall sensors detect the position of the motor rotor relative to the stator winding of each of three phases. Therefore, positions of two adjacent switch-type Hall sensors have a 120-degree electric angle difference therebetween. the motor actual rotating direction can be judged according to a sequence of the square wave signals generated by any two or all of the three switch-type Hall sensors. When the window lift motor  10  is a single phase brushless direct current motor, the rotation direction judgment unit  27  is not included, and the rotor position sensing unit  40  needs only one switch-type Hall sensor. Of course, as noted above, when the rotation direction judgment unit  27  is included, two switch-type Hall sensors are needed, one of which is used to operate the motor, and both of which are used in combination to judge the motor rotating direction. 
         [0020]    The inverter  30  is a bridge switch circuit. Referring to  FIG. 3 , when the three-phase brushless direct current motor is used, the bridge switch circuit is typically a three-phase bridge switch circuit having six power transistor switches. Referring to  FIG. 4 , when the single-phase brushless direct current motor is used, the bridge switch circuit is typically an H-bridge switch circuit having four transistor switches. The power transistor switches may be metal-oxide-semiconductor field-effect transistors (MOSFETs). 
         [0021]    The anti-pinch module  50  includes a pulse counter  51 , a count comparator  53 , an obstacle judgment unit  55 , and an anti-pinch instruct unit  57 . Since the rotor position sensing unit  40  includes one or more switch-type Hall sensors, the rotor position sensing unit  40  generates square wave pulse signals as the motor rotor rotates. The number of the pulses is directly proportional to rotation turns of the rotor. The transmission module has a fixed reduction ratio. Therefore, the number of the pulses linearly corresponds to a position of the vehicle window, and the position of the vehicle window can be determined by recording the number of the pulses. In one embodiment, the window lift motor  10  is a three-phase brushless direct current motor, the rotor position sensing unit  40  includes three switch-type Hall sensors, and the pulse counter  51  are used to record the number of the pulses generated by the three switch-type Hall sensors during lifting up of the vehicle window  80 . In another embodiment, the vehicle window  80  is a single-phase brushless direct current motor, the rotor position sensing unit  40  includes two switch-type Hall sensors, and the pulse counter  51  is used to record the number of the pulses generated by one of the two switch-type Hall sensors during lifting up of the vehicle window  80 . The count comparator  53  is used to compare the number of the pulses recorded in the pulse counter  51  against a predetermined threshold, and determine whether or not the vehicle window is in an anti-pinch area according to a relationship between the recorded number of the pulses and the threshold. For example, the threshold includes a threshold upper limit and threshold lower limit. When the recorded number of the pulses falls between the threshold upper limit and the threshold lower limit, it is determined that the vehicle in window is in the anti-pinch area, such that the obstacle judgment unit  55  is initiated. 
         [0022]    The obstacle judgment unit  55  can determine whether the lifting vehicle window meets an obstacle by measuring at least one of a motor speed, a current of the motor windings and a motor output torque and comparing the measured parameter against a preset threshold. A width of the pulses generated by the rotor position sensing unit  40  has a positive correlation with the rotation speed of the window lift motor  10  and can therefore be used to indicate the motor speed. In one embodiment, the obstacle judgment unit  55  includes a pulse width recorder and a pulse width comparator. The pulse width recorder is used to record the width of the pulses generated by the rotor position sensing unit  40 . The pulse width comparator is used to compare the recorded pulse width against a preset threshold. When the recorded pulse width is greater than the preset threshold, the obstacle judgment unit  55  determines that there is an obstacle. When the vehicle window  10  is a three-phase brushless direct current motor, the rotor position sensing unit  40  includes three switch-type Hall sensors, and the pulse width recorder is used to record the width of the pulses generated by one of the switch-type Hall sensors. When the vehicle window  10  is a single-phase brushless direct current motor, the rotor position sensing unit  40  includes two switch-type Hall sensors, the pulse width recorder is used to record the width of the pulses generated by one of the switch-type Hall sensors. 
         [0023]    The anti-pinch instruction unit  57  is connected to the motor drive/control module  20 . When the obstacle judgment unit  55  judges that there is an obstacle, the anti-pinch instruction unit  57  generates an anti-pinch instruction, and the data processing unit  23  of the motor drive/control module  20  performs data processing according to the anti-pinch instruction to obtain a corresponding anti-pinch control signal. The driving unit  25  of the motor drive/control module  20  generates an anti-pinch driving signal according to the anti-pinch control signal and drives the inverter  30  to perform the anti-pinch operation, making the window lift motor  10  rotate reversely. 
         [0024]    Referring to  FIG. 5 , a vehicle window lift control method according to one embodiment of the present invention includes the following steps. 
         [0025]    S 10 : a brushless direct current motor is provided to drive the vehicle window to lift up or lower down. 
         [0026]    A rotary shaft of the brushless direct current motor is connected to the vehicle window through a transmission mechanism. The window lift motor is connected to the vehicle window through a transmission assembly including a gearbox, traction cables and the like, such that power outputted from the rotary shaft of the window lift motor is transmitted to the vehicle window to form a traction force to drive the vehicle window to lift up or lower down. An external power supply supplies power to the brushless direct current motor through an inverter. 
         [0027]    S 20 : the brushless direct current motor is started in a desired direction or stopped according to an external command. The step S 20  includes the following steps: 
         [0028]    S 21 : a data processing is perfoiiiied according to an external command to obtain a corresponding motor control instruction. The external command includes an instruction of lifting up, lowering down or stopping the vehicle window that is inputted through a vehicle window button. 
         [0029]    S 22 : Inverter is driven according to the motor control instruction to supply or cut off power to various windings of the brushless direct current motor, thereby starting the motor in a desired direction or stopping the motor. 
         [0030]    S 30 : Rotor position is detected with a rotor sensing unit, a motor actual rotating direction is determined according to a sequence of the position feedback signals, and the actual rotating direction is compared against a rotating direction controlled by the control signal. If the two rotating directions are inconsistent, a failure signal is generated. 
         [0031]    S 40 : The inverter is driven to ensure continuous running of the motor according to rotor positon feedback signals. 
         [0032]    S 50 : it is deteiiiiined whether or not the vehicle window is in an anti-pinch area. 
         [0033]    The step S 50  includes the following steps: 
         [0034]    S 51 : the number of the position feedback signals is recorded. In one embodiment, recording the number of the position feedback signals is performed using a counter to record the number of the square wave pulses. 
         [0035]    S 52 : the recorded number of the position feedback signals is compared against a preset threshold, and whether or not the vehicle window is in the anti-pinch area is determined according to the relationship between the number of the position feedback signals and the preset threshold. In one embodiment, the preset threshold has a threshold upper limit and a threshold lower limit. When the number of the feedback signals falls between the threshold upper limit and the threshold lower limit, it is determined that the vehicle window is in the anti-pinch area. 
         [0036]    S 60 : it is determined whether or not the lifting vehicle window meets an obstacle when it is determined that the vehicle window is in the anti-pinch area. 
         [0037]    The step S 60  includes the following steps. 
         [0038]    S 61 : an operational parameter of the brushless direct current motor is detected. The parameter includes any one or more of a motor rotating speed, a current of the motor windings, and a motor output torque. When the feedback signals generated by the rotor position sensing unit are square wave pulse signals, a pulse width of the pulse signals can be used to indicate the motor rotating speed. In one embodiment, this step records the width of the pulses generated by the position sensing unit. 
         [0039]    S 62 : the detected operational parameter of the brushless direct current motor is compared against a preset threshold, and whether or not the lifting vehicle window meets an obstacle is determined according to the relationship between the detected operational parameter of the brushless direct current motor and its corresponding threshold. In one embodiment, the recorded width of the pulses generated by the position sensing unit is compared against a threshold of the pulse width. It is determined that there is an obstacle when the recorded width of the pulses generated by the position sensing unit is greater than the threshold. 
         [0040]    S 70 : when it is determined that there is an obstacle, the motor is controlled to perform an anti-pinch operation. 
         [0041]    The step S 50  comprises the following steps: 
         [0042]    S 51 : when it is determined that there is an obstacle, an anti-pinch instruction is generated. 
         [0043]    S 52 : a corresponding anti-pinch control signal is obtained by data processing according to the anti-pinch instruction. 
         [0044]    S 53 : according to the anti-pinch control signal, a driving signal is generated which is used to drive the inverter to perform the anti-pinch operation. The anti-pinch operation includes making the brushless direct current motor rotate reversely. 
         [0045]    Although the invention is described with reference to one or more embodiments, the above description of the embodiments is used only to enable people skilled in the art to practice or use the invention. It should be appreciated by those skilled in the art that various modifications are possible without departing from the spirit or scope of the present invention. The embodiments illustrated herein should not be interpreted as limits to the present invention, and the scope of the invention is to be determined by reference to the claims that follow.