Abstract:
A hybrid control system and method includes an offset candidate value determination step wherein an offset candidate value of a resolver is determined based on predetermined data; a zero current control step wherein all currents are controlled at zero; a voltage detection step wherein the voltage generated in the drive motor is detected while the currents are controlled at zero; an average value calculation step wherein the average value of the voltage is calculated using the detected voltage values; and a final offset value calculation step wherein the final offset valve is calculated using the average value and the offset candidate value. As such, a final offset value is quickly and accurately calculated.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims priority to and the benefit of Korean Patent Application No. 10-2011-0090312 filed in the Korean Intellectual Property Office on Sep. 6, 2011, the entire contents of which are incorporated herein by reference. 
       BACKGROUND OF THE INVENTION 
       [0002]    (a) Field of the Invention 
         [0003]    The present invention relates to a system and control method of a hybrid vehicle that powers the vehicle by combining engine output and motor output according to a driving condition, which improves fuel efficiency to reduce the rate of fuel consumption. 
         [0004]    (B) Description of the Related Art 
         [0005]    Generally, a drive motor is mounted in a hybrid vehicle. The drive motor includes a stator and a rotor, and a resolver is disposed to measure an absolute position of the rotator against the stator. 
         [0006]    In particular, the resolver is disposed near the drive motor, and an offset error is generated by the tolerance thereof and values detected by the mechanical/electrical error of an inner coil. However, the absolute position of the rotator/stator of the drive motor is still not accurately measured by the offset error (value). 
         [0007]    The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art. 
       SUMMARY OF THE INVENTION 
       [0008]    The present invention has been made in an effort to provide a system and control method of a hybrid vehicle that provides more precise control of a motor, reduces the hybrid vehicle fabrication process time, and further reduces the cost of a vehicle having a resolver. 
         [0009]    A hybrid control method according to an exemplary embodiment of the present invention may include an offset candidate value determination step wherein predetermined data is used to determine an offset candidate value of a resolver by detecting a rotation position of a drive motor; a zero current control step wherein all currents are controlled to a zero value; a voltage detection step wherein the voltage generated in the drive motor is detected when the currents are set at zero; an average value calculation step wherein an average value of the voltage in the drive motor is calculated using the voltage values detected in the voltage detection step; and a final offset value calculation step wherein a final offset valve is calculated using the average voltage value and the offset candidate value. 
         [0010]    In particular, the offset candidate value is the median of predetermined data in the offset candidate value determination step. 
         [0011]    The final offset value is calculated by the below equation 5. 
         [0000]    
       
         
           
             
               
                 
                   
                     α 
                     = 
                     
                       
                         
                           α 
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                          
                         
                           ( 
                           
                             
                               
                                 v 
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                                 v 
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                               q 
                             
                           
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                   , 
                 
               
               
                 
                   Equation 
                    
                   
                       
                   
                    
                   
                     ( 
                     5 
                     ) 
                   
                 
               
             
           
         
       
     
         [0012]    Here, α=final offset value,  α *=median of offset candidate value,  V   d =average voltage value of axis d (“direct axis”),  V   q =average voltage value of axis q (“quadrature axis”). 
         [0013]    At the zero current control step, the current (I d ) at axis d and the current (I q ) at axis q are controlled to be 0. 
         [0014]    The hybrid control method may further include processes that make the motor/ISG (“integrated starting and generating”) and the engine become directly engaged by a clutch, and prevents the torque from the motor/ISG and the engine from being transmitted into a drive wheel. According to various embodiments, the voltage detection step is performed for a predetermined sampling time. In particular, the voltage value is detected in a predetermined cycle in the sampling time in the average calculation step. 
         [0015]    According to an exemplary embodiment of the present invention, a control method for a hybrid vehicle uses a predetermined offset value for a resolver that is disposed within the vehicle so as to detect a rotation position of a drive motor, and voltage value is detected in the drive motor when the drive motor is controlled to a zero current so as to quickly and accurately calculate a final offset value. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0016]    The drawings illustrate exemplary embodiments of the present invention and are not construed to limit any aspect of the invention. 
           [0017]      FIG. 1  is a schematic diagram of a hybrid vehicle according to an exemplary embodiment of the present invention. 
           [0018]      FIG. 2  shows equations for controlling a hybrid vehicle according to an exemplary embodiment of the present invention. 
           [0019]      FIG. 3  is a graph showing a voltage for controlling a hybrid vehicle according to an exemplary embodiment of the present invention. 
           [0020]      FIG. 4  is a flowchart showing a control method of a hybrid vehicle according to an exemplary embodiment of the present invention. 
       
    
    
       [0021]    It should be understood that the appended drawings are not necessarily to scale, presenting a somewhat simplified representation of various preferred features illustrative of the basic principles of the invention. The specific design features of the present invention as disclosed herein, including, for example, specific dimensions, orientations, locations, and shapes will be determined in part by the particular intended application and use environment. 
         [0022]    In the figures, reference numbers refer to the same or equivalent parts of the present invention throughout the several figures of the drawing. 
       DETAILED DESCRIPTION OF THE EMBODIMENTS 
       [0023]    Hereinafter, the present invention will be described more fully hereinafter with reference to the accompanying drawings, in which exemplary embodiments of the invention are shown. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention. 
         [0024]    Portions having no relation with the description will be omitted in order to explicitly explain the present invention, and the same reference numerals will be used for the same or similar elements throughout the specification. 
         [0025]    Also, the size and thickness of each element are arbitrarily shown in the drawings, and the present invention is not necessarily limited thereto, and in the drawings, the thickness of layers, films, panels, regions, etc., are exaggerated for clarity. 
         [0026]    It is understood that the term hybrid “vehicle” or “vehicular” or other similar term as used herein is inclusive of all hybrid motor vehicles in general such as passenger automobiles including sports utility vehicles (SUV), buses, trucks, various commercial vehicles, watercraft including a variety of boats and ships, aircraft, and the like, and includes parallel and series hybrid vehicles, semi-electric vehicles, plug-in hybrid electric vehicles, hydrogen-powered hybrid vehicles and other alternative combination type fuel vehicles (e.g. fuels derived from resources other than petroleum). As referred to herein, a hybrid vehicle is a vehicle that has two or more sources of power, for example both gasoline-powered and electric-powered vehicles. 
         [0027]      FIG. 1  is a schematic diagram of a hybrid vehicle according to an exemplary embodiment of the present invention. 
         [0028]    Referring to  FIG. 1 , a hybrid vehicle includes a motor/generator ( 100 , ISG: integrated starting and generating), an engine  110 , a clutch  115 , a drive motor  120 , a resolver  125 , a transmission  130 , a drive wheel  140 , and a control portion  150 . 
         [0029]    The motor/generator  100  starts the engine  110  or generates electricity by the engine  110  to charge a separate a battery (not shown). 
         [0030]    The engine  110  is connected to the transmission  130  through the clutch  115  and the drive motor  120  is disposed between the clutch  115  and the transmission  130 . 
         [0031]    The drive motor  120  assists the output of the engine  110  or inputs a rotation torque to the transmission  130  without operating the engine  110 . 
         [0032]    The control portion  150  controls the motor/generator  100 , the engine  110 , the clutch  115 , the drive motor  120 , and the transmission  130 . The general aspects and functions of the control portion  150  are well understood in the art, and can be in accordance with such general aspects and functions and, as such, a detailed description of these aspects and functions of the control portion  150  according to an exemplary embodiment of the present invention will be omitted. 
         [0033]    According to an exemplary embodiment, the engine  110  operates when the clutch  115  is engaged, and the engine  110 , the motor/generator  100 , and the drive motor  120  are all rotated at the same speed. In this condition, the engine  110  is operated in an idle state, while the motor/generator  100  and the drive motor  120  function as a generator by a driving torque of the engine  110 . 
         [0034]    The resolver  125  detects absolute position of the rotator with respect to the stator in the drive motor  120 , transfers the detected position to the control portion  150 , and the control portion  150  applies an offset value for an assembly clearance to compensate and provide a more accurate rotation position of the rotator. 
         [0035]    In a case that the drive motor  120 , the resolver  125 , or the motor/generator  100  is replaced or repaired, there is often a problem in compensating the rotation position detected by the resolver  125  near the drive motor  120  with a conventional offset value. Accordingly, the offset value of the resolver  125  is reset. 
         [0036]      FIG. 2  shows equations for controlling a hybrid vehicle according to an exemplary embodiment of the present invention. 
         [0037]    Equation (1) of  FIG. 2  is a voltage differential equation that is related to the resolver  125 , which is as follows: 
         [0000]    
       
         
           
             
               
                 
                   
                     
                       
                         
                           
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                   Equation 
                    
                   
                       
                   
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                     ( 
                     1 
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         [0038]    In this Equation (1), R is a resistance that is applied to the drive motor  120 , L d  is an axis d inductance coefficient, L q  is an axis q inductance coefficient, Ψ F  is the size of magnetic flux, α is the final offset value, and α* is the offset candidate value. 
         [0039]    Further, in Equation (1), i d  is axis d current, i q  is axis q current, v d  is axis d voltage, v q  is axis q voltage, and ω is rotator angle speed. 
         [0040]    In Equation (1), if axis d current (i d ) and axis q current (i q ) converge to 0 through a zero current control, then Equation (1) becomes Equation (2). 
         [0000]    
       
         
           
             
               
                 
                   
                     
                       
                         
                           
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                   Equation 
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                     ( 
                     2 
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         [0041]    From the two equations of Equation (2), Equation (3) is obtained as follows: 
         [0000]    
       
         
           
             
               
                 
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                   = 
                   
                     
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                       * 
                     
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                   Equation 
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                     ( 
                     3 
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         [0042]    Referring to Equation (3), an offset candidate value (α*), axis d voltage (V d ), and axis q voltage (V q ) are used to calculate an offset value (α). 
         [0043]    In particular, the offset candidate value is one value that is selected among the offset candidate values. Because the axis d voltage and the axis q voltage are varied according to a sampling time because of a sensor noise, this is described in further detail as follows. 
         [0044]      FIG. 3  is a voltage graph with a sensor noise while currents are controlled to zero according to an exemplary embodiment of the present invention. 
         [0045]    Firstly, referring to  FIG. 3 , the horizontal axis represents time and the vertical axis represents voltage. 
         [0046]    As shown, axis d voltage (V d ) and axis q voltage (V q ) are detected in the drive motor  120 , and the axis d voltage (V d ) and the axis q voltage (V q ) are varied depending on time. 
         [0047]    Accordingly, the axis d voltage and the axis q voltage are detected for a predetermined time by a predetermined cycle, and the average value thereof is used. 
         [0048]    In the below Equation (4), an average value of the axis d voltage is used to calculate an axis d voltage average value (  V   d ), and an average value of the axis q voltage is used to calculate an axis q voltage average value (  V   q ). 
         [0000]    
       
         
           
             
               
                 
                   
                     
                       
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                     ( 
                     4 
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         [0049]    Accordingly, if Equation (4) is applied to Equation (3), Equation (5) is provided. 
         [0000]    
       
         
           
             
               
                 
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                   = 
                   
                     
                       
                         α 
                         _ 
                       
                       * 
                     
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                         tan 
                         
                           - 
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                        
                       
                         ( 
                         
                           
                             
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                         ) 
                       
                     
                   
                 
               
               
                 
                   Equation 
                    
                   
                       
                   
                    
                   
                     ( 
                     5 
                     ) 
                   
                 
               
             
           
         
       
     
         [0050]    Accordingly, median values of (  α *) the offset candidate value, the axis d voltage average value (  V   d ), and the axis q voltage average value (  V   q ) are applied to Equation 5 to quickly calculate the offset value (α). The thus calculated offset value is transferred to the control portion  150 , and the value is used to compensate the absolute position of a rotator of the drive motor  120 . 
         [0051]      FIG. 4  is a flowchart showing a control method of a hybrid vehicle according to an exemplary embodiment of the present invention. 
         [0052]    In particular, referring to  FIG. 4 , at S 400 , a control for compensating the signal detected by the resolver  125  starts. 
         [0053]    At S 410 , a median of offset values is selected as an offset candidate value. For example, if the offset values range from 1 to a maximum value of 10, the median thereof might be, for example, 5.5. 
         [0054]    After the offset candidate value is selected in a S 420 , the drive motor  120  is current controlled to zero current. Here, an axis d current and an axis q current of the drive motor  120  are controlled to be 0 through use of a current controller. 
         [0055]    At S 430 , it is determined whether an operating condition is normal. The normal condition in an exemplary embodiment of the present invention signifies that the axis d current and the axis q current of the drive motor  120  are 0. 
         [0056]    Further, the engine  110  is operated in an idle condition and the drive motor  120  is operated by the engine  110  through the clutch  115 . Also, the transmission  130  separates an input shaft from an output shaft, and a torque is not transferred to a drive wheel  140  to provide a parking condition (P). 
         [0057]    At S 440 , each average value of N number of axis d voltages and N number of axis q voltages is calculated during a predetermined sampling period, and a median of the offset candidate value (  α *), the axis d voltage average value (  V   d ), and the axis q voltage average value (  V   q ) are applied to Equation (5) to calculate a final offset value (α) at S 450 . 
         [0058]    The final offset value that is calculated is transmitted to the control portion  150 , and the controller  150  compensates the signals detected in the resolver  125 . 
         [0059]    according to an exemplary embodiment of the present invention, a median is selected in the offset candidate values, but in other embodiments an average value can be applied to calculate the final offset value. 
         [0060]    Furthermore, the above described processes and methods may be performed by control logic embodied as computer readable media on a computer readable medium containing executable program instructions executed by a processor, controller or the like. Examples of the computer readable mediums include, but are not limited to, ROM, RAM, compact disc (CD)-ROMs, magnetic tapes, floppy disks, flash drives, smart cards and optical data storage devices. The computer readable recording medium can also be distributed in network coupled computer systems so that the computer readable media is stored and executed in a distributed fashion, e.g., by a telematics server. 
         [0061]    While this invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims. 
       DESCRIPTION OF SYMBOLS 
       [0000]    
       
         
           
               100 : motor/generator 
               110 : engine 
               115 : clutch 
               120 : drive motor 
               125 : resolver 
               130 : transmission 
               140 : drive wheel 
               150 : control portion