Abstract:
A control method of a vehicle having a motor according to an exemplary embodiment of the present invention can include confirming that a speed of the motor is not 0 and an output torque thereof is 0 in a condition that the vehicle is being operated, confirming that a voltage of the motor converges to a regular value, and accumulating control data for the motor and processing the control data to calculate an offset value of a resolver. Accordingly, the control method of a vehicle effectively determines whether the offset of the resolver is to be compensated without affecting the drivability of the vehicle.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims priority to and the benefit of Korean Patent Application No. 10-2011-0126332 filed in the Korean Intellectual Property Office on Nov. 29, 2011, the entire contents of which are incorporated herein by reference. 
       FIELD OF THE INVENTION 
       [0002]    The present invention relates to a control method of a hybrid vehicle that automatically measures an error (offset) of a resolver and compensates the offset value of the error so as to accurately control torque and speed of a motor. 
       BACKGROUND OF THE INVENTION 
       [0003]    Generally, an MCU (motor control unit) is used to control an induction motor or a synchronous motor that is used in an electric vehicle and a hybrid vehicle. For this, a coordinate system is established according to a position of flux. Accordingly, a resolver is used to read an absolute position of a motor rotator. 
         [0004]    A resolver is a kind of transformer to transmit an excitation voltage to a first side winding (input side), and if an axis is rotated, a magnetic coupling coefficient is transformed and a voltage that varies the amplitude of a carrier is generated in a second side winding (output). 
         [0005]    The winding is arranged such that the voltage varies along sine and cosine curves based on the rotation angle. Accordingly, the rotation angle of the resolver can be detected by reading the carrier amplitude of the sine output and the cosine output. 
         [0006]    A resolver that is operated according to the above principle senses speed and phase data of the motor and transfers the position data of the motor rotator to the MCU, and these are used for generating a torque order and speed order. 
         [0007]    However, an offset or error can be generated while mounting the resolver, so an accurate position of the rotator of the motor cannot be detected because of the error or the offset, and this causes the motor to be abnormally operated. 
         [0008]    Accordingly, as a method for compensating the sensing error, a measuring instrument such as an oscilloscope is used to analyze a waveform of the resolver and line-to-line counter-electromotive force of the motor and then an offset value for the sensing error is compensated. 
         [0009]    This method is performed by a manual operation of an operator, so the time required is increased, the amount of work is increased, and all vehicles have to be compensated. Also, the compensation value can vary according to the skill level of the operator. 
         [0010]    The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it can 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 
       [0011]    The present invention has been made in an effort to provide a control method of a vehicle having a motor having advantages of monitoring an offset of a resolver while driving without affecting drivability and determining whether the offset is to be compensated. 
         [0012]    A control method of a vehicle having a motor according to an exemplary embodiment of the present invention can include confirming that a speed of the motor is not 0 and an output torque thereof is 0 in a condition that the vehicle is being operated, confirming that a voltage of the motor converges to a regular value, and accumulating control data the motor and processing the control data to calculate an offset value of a resolver. 
         [0013]    The offset mode can be performed in a condition that the speed of the vehicle is not 0. 
         [0014]    A point that an output torque of the motor is 0 can be extended to can be within a predetermined speed range of the motor. The predetermined speed range can be between about 1,000 RPM and about 2,000 RPM. 
         [0015]    While the current of the motor converges to the predetermined value, an axis D voltage of the motor can converge to a predetermined range. The predetermined range can be between about −1.2 V and about +1.2 V. 
         [0016]    While the current of the motor converges to the predetermined value, an axis Q voltage of the motor can converge to a predetermined range. The predetermined range can be between about −1.2 V and about +1.2 V. 
         [0017]    While the current of the motor converges to the predetermined value, an axis D voltage and an axis Q voltage of the motor can converge to a predetermined range. The predetermined range can be between about −1.2 V and about +1.2 V. 
         [0018]    When it is confirmed that the torque of the motor is 0, the motor can be controlled in a 0-current condition. 
         [0019]    The offset value can be calculated in accordance with equations v d =ωψ F  sin(α−α*) and v q =ωψ F  cos(α−α*), wherein v d  denotes an axis D voltage, v q  denotes an axis Q voltage, ω denotes a rotator angle speed, ψ F  denotes a size of flux, α denotes a final offset value, and α* denotes an offset candidate value. 
         [0020]    The regular value can be between about 0.3 V and about 1 V. 
         [0021]    A non-transitory computer-readable medium containing program instructions executed by a processor or controller to implement a control method of a vehicle having a motor according to an exemplary embodiment of the invention can include: program instructions that confirm that a speed of the motor is not 0 and an output torque thereof is 0 in a condition that the vehicle is being operated; program instructions that confirm that a voltage of the motor converges to a regular value; and program instructions that accumulate control data for the motor and processing the data to calculate an offset value of a resolver. 
         [0022]    The control method of a vehicle having a motor according to an exemplary embodiment of the present invention effectively determines whether the offset of the resolver is to be compensated without affecting the drivability of the vehicle. 
       DEFINITIONS 
       [0023]    The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” and/or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items. 
         [0024]    It is understood that the term “vehicle” or “vehicular” or other similar term as used herein is inclusive of 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 hybrid vehicles, electric vehicles, plug-in hybrid electric vehicles, hydrogen-powered vehicles and other alternative 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. 
         [0025]    Unless specifically stated or obvious from context, as used herein, the term “about” is understood as within a range of normal tolerance in the art, for example within 2 standard deviations of the mean. “About” can be understood as within 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, 1%, 0.5%, 0.1%, 0.05%, or 0.01% of the stated value. Unless otherwise clear from the context, all numerical values provided herein are modified by the term “about.” 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0026]    While the drawings are 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 drawings. 
           [0027]      FIG. 1  is a schematic diagram of a vehicle having a motor according to an exemplary embodiment of the present invention. 
           [0028]      FIG. 2  is a circuit diagram for an MCU control portion controlling a motor according to an exemplary embodiment of the present invention. 
           [0029]      FIG. 3  is a schematic diagram of a resolver offset determiner according to an exemplary embodiment of the present invention. 
           [0030]      FIG. 4  is a graph showing a torque profile according to speed of a motor disposed in a hybrid vehicle according to an exemplary embodiment of the present invention. 
           [0031]      FIG. 5  is a graph showing a state that a torque profile is changed according to speed of a motor disposed in a hybrid vehicle according to an exemplary embodiment of the present invention. 
           [0032]      FIG. 6  is a table showing an offset determination mode entry condition of a resolver disposed in a hybrid vehicle according to an exemplary embodiment of the present invention. 
           [0033]      FIG. 7  is a table showing an offset determination mode entry condition of a resolver disposed in a hybrid vehicle and a driving mode according to an exemplary embodiment of the present invention. 
           [0034]      FIG. 8  is a graph showing a v d  value in a condition that an offset error of a resolver is formed in a hybrid vehicle according to an exemplary embodiment of the present invention. 
           [0035]      FIG. 9  is a flowchart showing a method for entering a mode for determining an offset of a resolver in a hybrid vehicle according to an exemplary embodiment of the present invention. 
       
    
    
       [0036]    The following legend of reference numerals used in the figures is provided for the reader&#39;s convenience:
         110 : motor     120 : resolver     130 : motor control unit     140 : high voltage battery     150 : main relay     160 : capacitor     210 : current order generator     220 : current controller     230 : axis converter     240 : PWM (pulse-width modulation) generator     250 : PWM inverter     260 : resolver offset determiner     310 : speed/torque determiner     320 : 0-current control determiner     330 : voltage sensing and resolver offset calculating portion       
 
       DETAILED DESCRIPTION OF THE EMBODIMENTS 
       [0052]    Hereinafter, the present invention will be described more fully with reference to the accompanying drawings, in which exemplary embodiments of the invention are shown. As those skilled in the art will realize, the described embodiments can be modified in various different ways, all without departing from the spirit or scope of the present invention. 
         [0053]    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. 
         [0054]    In the drawings, size and thickness of each element are approximately shown for better understanding and ease of description. Therefore, the present invention is not limited to the drawings, and the thicknesses of layers, films, panels, regions, etc., can be exaggerated for clarity. 
         [0055]      FIG. 1  is a schematic diagram of a vehicle having a motor according to an exemplary embodiment of the present invention. 
         [0056]    Referring to  FIG. 1 , a vehicle having a motor includes the motor  110 , a resolver  120 , a motor control unit  130 , a high voltage battery  140 , a main relay  150 , a capacitor  160 , and a BMS (battery management system), wherein the system can be applied to a hybrid vehicle, an electric vehicle, and a fuel cell vehicle. The motor  110  can output torque developed by electricity and can generate electricity. 
         [0057]    The motor  110  is controlled by the motor control unit  130 , and the motor control unit  130  includes an inverter that transforms a DC current to a variable frequency and an AC current of a variable voltage, and a control portion controlling current and voltage. 
         [0058]    The resolver  120  is a motor position sensor that provides rotation position information of the motor  110  to the motor control unit  130 . The motor control unit  130 , in turn, controls the current and voltage that is supplied to the motor  110 . 
         [0059]      FIG. 2  is a circuit diagram for an MCU control portion controlling a motor according to an exemplary embodiment of the present invention. 
         [0060]    Referring to  FIG. 2 , a control portion of an MCU  130  includes a current order generator  210 , a current controller  220 , an axis converter  230 , a PWM generator  240 , a PWM inverter  250 , and a resolver offset determiner  260 . 
         [0061]    If a torque order or a speed order is input from a higher rank control portion, the motor control unit  130  generates axis D and axis Q current orders in the current order generator  210 , and the current controller  220  performs current control such that the inverter current follows the current order. 
         [0062]    The axis converter  230  transforms current from axis D and axis Q to three phases, the PWM generator  240  transmits a PWM switching signal to an inverter based on the current order, and the PWM inverter  250  controls the motor through switching based on the PWM switching signal. 
         [0063]    The resolver offset determiner  260  uses the torque order and current order that are transferred from the higher rank control portion, current that is fed back from the motor, axis D and Q voltages that are monitored, and the like to determine the offset of the resolver  120 . 
         [0064]    The present invention enters into a resolver offset determination mode in a 0-torque period during which 0-current controlling is possible in a driving condition, and performs 0-current controlling in a condition in which the drivability of the vehicle is not affected to determine the offset of the resolver. 
         [0065]      FIG. 3  is a schematic diagram of a resolver offset determiner according to an exemplary embodiment of the present invention. 
         [0066]    Referring to  FIG. 3 , the resolver offset determiner  260  includes a speed/torque determiner  310 , a 0-current control determiner  320 , and a voltage sensing and resolver offset calculating portion  330 . 
         [0067]    The speed/torque determiner  310  monitors the speed and torque order of the motor and the 0-current control determiner  320  monitors a torque that is demanded by the motor. 
         [0068]    Further, the voltage sensing and resolver offset calculating portion  330  senses the voltage according to the speed and the 0-current condition of the motor to determine the offset of the resolver. In one embodiment, the offset of the resolver is determined in accordance with Equation (1) below. 
         [0000]    
       
         
           
             
               
                 
                   
                     
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         [0069]    In Equation (1), R denotes a resistance that is applied to the motor  110 , L d  denotes an axis D inductance constant, L q  denotes an axis Q inductance constant, ψ F  denotes a size of flux, α denotes a final offset value, and α* denotes an offset candidate value. 
         [0070]    Further, in Equation (1), i d  denotes an axis D current, i q  denotes an axis Q current, v d  denotes an axis D voltage, v q  denotes an axis Q voltage, and ω denotes a rotator angle speed. 
         [0071]    In the first equation, if the axis D current (i d ) and the axis Q current (i q ) converge to 0 by 0-current control, Equation (1) can be transformed to Equation (2) below. 
         [0000]        v   d =ωψ F  sin(α−α*)
 
         [0000]        v   q =ωψ F  cos(α−α*)  (2)
 
         [0072]      FIG. 4  is a graph showing a torque profile according to a speed of a motor disposed in a hybrid vehicle according to an exemplary embodiment of the present invention. 
         [0073]    Referring to  FIG. 4 , the horizontal axis denotes a vehicle speed, and the vertical axis denotes an output torque of a motor. 
         [0074]    The motor  110  outputs a torque at a slower speed than a predetermined value, and the motor  110  generates electricity to perform regeneration at a faster speed than a predetermined value. 
         [0075]      FIG. 5  is a graph showing a state that a torque profile is changed according to a speed of a motor disposed in a hybrid vehicle according to an exemplary embodiment of the present invention. 
         [0076]    Referring to  FIG. 5 , the horizontal axis denotes a vehicle speed, and the vertical axis denotes an output torque of a motor. Compared to  FIG. 4 , the torque profile is transformed and the 0-torque section is extended in a condition that a vehicle speed ranges within a predetermined range such that the system can easily enter into an offset determination mode. 
         [0077]      FIG. 6  is a table showing an offset determination mode entry condition of a resolver disposed in a hybrid vehicle according to an exemplary embodiment of the present invention. 
         [0078]    Referring to  FIG. 6 , if a motor speed is not 0, an output torque thereof is 0, and axis D and Q currents are 0, the vehicle enters into a resolver offset determination mode. 
         [0079]      FIG. 7  is a table showing an offset determination mode entry condition of a resolver disposed in a hybrid vehicle and a driving mode according to an exemplary embodiment of the present invention. 
         [0080]    Referring to  FIG. 7 , in a condition that a motor speed is not 0, an output torque thereof is 0, and axis C and Q currents are 0, the vehicle enters into a resolver offset determination mode. 
         [0081]      FIG. 8  is a graph showing v d  values in a condition that an offset error of a resolver is formed in a hybrid vehicle according to an exemplary embodiment of the present invention. 
         [0082]    Referring to  FIG. 8 , if the vehicle enters into a resolver offset determination mode, the current of the motor  110  converges to 0 by the 0-current control, the speed of the motor  110  varies in a predetermined range, and the axis D voltage (Vd) slowly converges to a predetermined value. 
         [0083]    As shown, a predetermined converging time is necessary to determine the offset of the resolver of the motor  110 . Accordingly, when the vehicle enters into a resolver offset determination mode during a driving condition, data is gathered, filtered, or averaged to perform calculation of the resolver after a predetermined time. 
         [0084]      FIG. 9  is a flowchart showing a method for entering a mode for determining an offset of a resolver in a hybrid vehicle according to an exemplary embodiment of the present invention. 
         [0085]    Referring to  FIG. 9 , it is determined whether a demanded torque of the motor  110  is 0 while driving in S 900 , and it is determined whether 0-current control is possible in S 910 . 
         [0086]    It is determined whether a speed of the motor  110  is 0 in S 920 , and it is determined whether data for the control converge to a predetermined value in S 930 . Data is gathered for a predetermined section in S 940 , the data is processed to determine whether an offset value of the resolver is to be compensated, and the control is ended in S 950 . 
         [0087]    The data includes all control data for the motor  110 , which includes a resistance that is applied to the motor  110 , an axis D inductance constant, an axis Q inductance constant, a size of flux, a final offset value, an offset candidate value, an axis D current, an axis Q current, axis D voltage, axis Q voltage, and an angle speed of a rotator. 
         [0088]    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. 
         [0089]    For example, although various aspects of the invention are in the context of a single unit or a plurality of units, it is understood that the invention can also be performed by a plurality of units or a single unit, respectively. 
         [0000]    Furthermore, the control logic of the present invention can be embodied as non-transitory computer-readable media on a computer-readable medium containing executable program instructions executed by a processor, controller or the like. Examples of computer-readable media 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 or a Controller Area Network (CAN).