FIELD 
       [0001]    An embodiment of the present invention relates to an electric vehicle control device. 
       BACKGROUND 
       [0002]    In general, motors (electric motors) mounted on electric vehicles and inverters driving the motors are manufactured in different places manufacturers), and wiring workers who connect motors and inverters on electric vehicles are mostly different from their manufacturers. Because of this, motors and inverters may be electrically wired (connected) erroneously. 
         [0003]    Such a problem may occur riot only during the manufacture of electric vehicles but also during inspection or replacement work for the motors or inverters. 
         [0004]    Further, the miswire causes the motors to reversely rotate. Conventionally, such miswire between the motors and the inverters is detected by detecting currents generated by the reverse rotations of the motors. 
       CITATION LIST 
     Patent Literature 
       [0005]    Patent Literature 1: Japanese Laid-open Patent Publication No. 2010-213557 
       SUMMARY OF THE INVENTION 
     Problem to be Solved by the Invention 
       [0006]    However, in an electric vehicle on which a number of motors are mounted, if a majority of the motors are correctly wired and normally rotate, the wheels of the electric vehicle are all rotated in the same direction. Accordingly, erroneously wired motors are prevented from reversely rotating and moved along with the motion of the wheels. They do not reversely rotate against the rotation of the correctly wired motors. 
         [0007]    Thus, the miswire cannot be detected by the conventional method as above, which may lead to an excessive amount of currents flowing into the erroneously wired motors due to the miswire and damaging the motors. 
         [0008]    In view of the above problem, the present invention aims to provide an electric vehicle control device which can accurately detect a miswire between motors and an inverter in an electric vehicle incorporating a plurality of motors. 
       Means for Solving Problem 
       [0009]    An electric vehicle control device of the embodiment comprises a plurality of motors capable of transmitting motive power to a wheel of an electric vehicle and an inverter that supplies electric power to drive the motors. A controller controls the inverter and compares, when the electric vehicle drives under a certain velocity condition, a q-axis voltage feedforward value VqFF and a q-axis voltage command value Vq* used for controlling driving of the motors, to detect an occurrence of miswire between the motors and the inverter when the following inequation is satisfied: VqFF≧1.5·Vq* 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0010]      FIG. 1  is a schematic configuration diagram of an electric vehicle system including an electric vehicle control device according to an embodiment. 
           [0011]      FIG. 2  is a schematic configuration block diagram of a controller. 
           [0012]      FIG. 3  is an illustrative diagram for the operation in the embodiment. 
       
    
    
     DETAILED DESCRIPTION 
       [0013]    Now, an embodiment will be described with reference to the accompanying drawings. 
         [0014]      FIG. 1  is a schematic configuration diagram of an electric vehicle system including an electric vehicle control device according to one embodiment. 
         [0015]    An electric vehicle system ET, as shown in  FIG. 1 , includes an overhead wire  1  that supplies alternating-current power, a pantograph  2  for receiving the supply of the alternating-current power from the overhead wire  1 , a master breaker  3  that interrupts the alternating-current power supplied from the overhead wire  1  via the pantograph  2 , wheels  5  of an electric vehicle grounded via a rail  4 , an operation board  6  including a master controller, with which a driver conducts various kinds of operation, and a display board  7  that displays various kinds of information such as vehicle velocity. 
         [0016]    The electric vehicle system ET further includes a transformer  10  that transforms a voltage of the alternating-current power supplied from the overhead wire  1 , a current-limiting resistor  11  for limiting an inrush current, a contactor  12  that supplies the power from the transformer  10  to a following stage, and a current-limiting resistance contactor  13  for forming a closed circuit including the current-limiting resistor  11  prior to a closed state (ONstate) of the contactor  12  for the purpose of limiting the inrush current at the time of closing the contactor  12 . 
         [0017]    The electric vehicle system ET further includes a converter  14  that converts the alternating-current power supplied via the contactor  12  into direct-current power with a certain voltage, an inverter (variable voltage, variable frequency inverter)  15  that converts the direct-current power output from the converter  14  to three-phase alternating-current power with a desired frequency and voltage, and a current sensor unit  16  including current sensors which detect the U-phase, V-phase, and W-phase currents of the three-phase alternating-current power output from the inverter  15 , respectively. 
         [0018]    The electric vehicle system ET further includes a plurality of motors  18   a,    18   b  driven by the inverter  15  to transmit motive power to the corresponding wheels  5 , velocity sensors  19   a,    19   b  that detect the velocities of the motors  18   a,    18   b,  respectively, and a controller  100  that controls the driving of the motors  18   a,    18   b.    
         [0019]      FIG. 2  is a schematic configuration block diagram of the controller. The controller  100  includes a three-phase/two-phase converter  110  which receives a U-phase current signal Iu, a V-phase current signal Iv, and a W-phase current signal  1   w  from the current sensor unit  16  for three-phase to two-phase conversion to obtain a d-axis current Id and a q-axis current Iq, and a current command calculator  120  which receives a magnetic flux command Φ* and a torque command T* to calculate a d-axis current command Id* and a q-axis current command Iq* for output. 
         [0020]    The controller  100  further includes a feedback (FL) voltage calculator  111  which receives the d-axis current Id, the q-axis current Iq, the d-axis current command Id*, and the q-axis current command Iq* to calculate a d-axis feedback voltage VdFB and a q-axis feedback voltage VqFB for output, and a feedforward (FF) voltage calculator  121  which receives the d-axis current command Id* and the q-axis current command Iq* to calculate a d-axis feedforward voltage VdFF and a q-axis feedforward voltage VqFF for output. 
         [0021]    The controller  100  further includes a first adder  112  which adds the d-axis feedforward voltage VdFF to the d-axis feedback voltage VdFB to output a d-axis voltage command Vd*, a second adder  113  which adds the q-axis feedforward voltage VqFF to the q-axis feedback voltage VqFB to output a q-axis voltage command Vq*, and a drive controller  114  which generates a PWM control signal SPWM according to the d-axis voltage command Vd* and the q-axis voltage command Vq* for output to the inverter  15 . 
         [0022]    The controller  100  further includes an amplifier  115  which amplifies the q-axis voltage command Vq* by 1.5 times for output as a comparative voltage Vqc (=1.5·Vq*), a miswire detector  122  which detects a miswire according to the comparative voltage Vqc and the q-axis feedforward voltage VqFF to output a miswire detection output signal SER, and a vehicle velocity detector  123  which detects the velocity of the electric vehicle according to the outputs of the velocity sensors  19   a,    19   b.    
         [0023]    The configuration of the miswire detector  122  is now described. 
         [0024]    The miswire detector  122  includes a differential calculator  130  which calculates a difference between the comparative voltage Vqc and the q-axis feedforward voltage VqFF to output a differential voltage VV* (=VqFF−Vqc). 
         [0025]    The miswire detector  122  further includes a comparator  131  which determines whether or not the differential voltage VV* is equal to or above 0, and turns a miswire detection signal SED to “H”-level upon determining that the differential voltage is 0 or more, that is, VqFF≧Vqc. 
         [0026]    The miswire detector  122  further includes an AND circuit  132  that receives a notch position signal SNP which turns to “H”-level when a notch position of the master controller is at or below a 3-notch (maximal notch position during examination or inspection), receives a motion detection signal SMV which turns to “H”-level when the electric vehicle drives at a velocity of 30 km/hr (maximal allowable velocity during examination or inspection) or less, and receives the miswire detection signal, to obtain a logical AND of these signals and output a miswire detection output signal SER. 
         [0027]    Next, the operation in the embodiment will be described. 
         [0028]    In the following both of the motors  18   a,    18   b  are assumed to be connected to the inverter  15  via wiring. 
         [0029]    In such a connection, an operator places the master breaker  3  in an open state (OFF state) and activates the pantograph  2  with a not-shown activator to contact the overhead wire  1 . 
         [0030]    Then, the operator places the current-limiting resistance contactor  13  in a closed state (ON state) to form the current-limiting resistor  11  as a closed circuit including the transformer  10  and the converter  14 . 
         [0031]    As a result, the difference in voltage (voltage difference equivalent to a voltage drop in the current-limiting resistor  11 ) between both ends of the master breaker  3  is reduced to small, thus, with the occurrence of inrush currents inhibited, the operator can place the master breaker  3  in the closed state. 
         [0032]    In response to the closed state of the master breaker  3 , the transformer  10  transforms the voltage of the alternating-current power supplied from the overhead wire  1  and supplies the voltage to the converter  14 . 
         [0033]    The converter  14  is supplied with the alternating-current power from the overhead wire  1  at the transformed voltage by the transformer  10  to convert the supplied alternating-current power to direct-current power with a certain voltage for output to the inverter  1   
         [0034]    The inverter  15  converts the direct-current power output from the converter  14  to three-phase (U-phase, V-phase, W-phase) alternating-current power with a desired frequency and voltage according to a later-described PWM control signal SP input from the drive controller  114 , and supplies the alternating-current power to the motors  18   a,    18   b.    
         [0035]    In parallel thereto, the current sensor unit detects a U-phase current, a V-phase current, and a W-phase current to output a U-phase current signal Iu, a V-phase current signal Iv, and a W-phase current signal Iw to the three-phase/two-phase converter  110  of the controller  100 . 
         [0036]    The vehicle velocity detector  123  detects the velocity of the electric vehicle according to the outputs of the velocity sensors  19   a,    19   b  and outputs, to the AND circuit  132 , the motion detection signal SMV which turns “N”-level when the electric vehicle drives at the velocity of 30 km/hr (=a preset value as a maximal allowable velocity during examination or inspection) or less. 
         [0037]    Also input to the AND circuit  132  is the notch position signal SNP which turns to “H”-level when the notch position of the master controller on a control platform is at 3-notch (=a preset value as a maximal notch position during examination or inspection) or less. 
         [0038]    The three-phase/two-phase converter  110  of the controller  100  receives the U-phase current signal Iu, the V-phase current signal Iv, and the W-phase current signal Iw from the current sensor unit  16  for three phase/two phase conversion to obtain the d-axis current Id and the q-axis current Iq for output to the feedback voltage calculator  111 . 
         [0039]    In parallel thereto, the current command calculator  120  receives the magnetic flux command Φ* and the torque command T* and calculates the d-axis current command Id* and the q-axis current command Iq* for output to the feedback voltage calculator  111  and the feedforward (FF) voltage calculator  121 . 
         [0040]    Thereby, the feedback voltage calculator  111  calculates the d-axis feedback voltage VdFB and the q-axis feedback voltage VqFB according to the input d-axis current Id, q-axis current Iq, d-axis current command Id*, and q-axis current command Iq* to output the voltages to the drive controller  114 . 
         [0041]    The feedforward (FE) voltage calculator  121  calculates the d-axis feedforward voltage VdFF and the q-axis feedforward voltage VqFF according to the input d-axis current command Id* and q-axis current command Iq* to output the d-axis feedforward voltage VdFF to the first adder  112  and output the q-axis feedforward voltage VqFF to the second adder  113  and the differential calculator  130  of the miswire detector  122 . 
         [0042]    The first adder  112  adds the d-axis feedforward voltage VdFF to the d-axis feedback voltage VdFB to output the d-axis voltage command Vd* to the drive controller  114 . The second adder  113  adds the q-axis feedforward voltage VqFF to the q-axis feedback voltage VqFB to output the q-axis voltage command Vq* to the drive controller  114  and the amplifier  115 . 
         [0043]    The drive controller  114  generates the PWM control signal SPWM according to the d-axis voltage command Vd* and the q-axis voltage command Vq* for output to the inverter  15 . 
         [0044]    The amplifier  115  amplifies the input q-axis voltage command Vq* by 1.5 times and outputs it as a comparative voltage Vqc (=1.5·Vq*) to the differential calculator  130  of the miswire detector  122 , Herein, the amplification rate of the amplifier  115  is set to 1.5 times because it was confirmed by test results that relative to the d-axis voltage command Vd* which can take various different values when actually input, the values during normalcy and the values during anomaly can be accurately distinguished. That is, it was confirmed that at VqFF ≧1.5·Vq*, anomaly can be accurately determined while at VqFF&lt;1.5·Vq*, normalcy can be accurately determined. 
         [0045]    The differential calculator  130  of the wire detector  122  calculates a difference between the comparative voltage Vqc and the q-axis feedforward voltage VqFF to output a differential voltage VV* (=VqFF−Vqc) to the comparator  131 . 
         [0046]      FIG. 3  is an illustrative diagram for the operation according to the embodiment. 
         [0047]    Hence, the comparator  131  determines whether or not the differential voltage VV* is equal to or exceeds a set value α(=0), and outputs the miswire detection signal SED at “H”-level to the AND circuit  132  when determining that the differential voltage VV* is 0 or more, that is, 
         [0000]        VqFF≧Vqc (=1.5· Vq *).
 
         [0048]    The AND circuit  132  receives the miswire detection signal SED, the notch position signal SNP, and the motion detection signal SMV and obtains a logical AND of the signals to output the miswire detection output signal SER. 
         [0049]    Thus, the AND circuit  132  outputs the miswire detection output signal SER at the “H”-level when the differential voltage VV* is 0 or more, that is, VqFF≧Vqc, the velocity of the electric vehicle is 30 km/hr (=a preset value as a maximal allowable velocity during examination or inspection) or less, and the notch position of the master controller on the control platform is at 3-notch or less (=a preset value as a maximal notch position during examination or inspection). 
         [0050]    Accordingly, when VqFF≧Vqc is satisfied during examination or inspection (at the velocity of 30 km/hr or less and the notch position at 3-notch or less), the miswire detector  122  determines presence of a miswire and outputs the miswire detection output signal SER at “H”-level. 
         [0051]    Meanwhile, the comparator  131  outputs the miswire detection signal SED at “L”-level to the AND circuit  132  when the differential voltage VV* is less than 0, that is, 
         [0000]        VqFF&lt;Vqc  (=1.5· Vq *)
 
         [0052]    The AND circuit  132  receives the miswire detection signal SED, the notch position signal SNP, and the motion detection signal SMV to obtain a logical AND of these signals and output the miswire detection output signal SER at “L”-level. Normal wiring between the motors  18   a,    18   b  and the inverter  15  is thus found. 
         [0053]    This accordingly makes it possible to accurately and easily detect the miswire between the motors  18   a,    18   b  and the inverter  15 . 
         [0054]    In this case, the miswire detection output signal SER is output to other controllers, the display board  7  provided in a driver&#39;s cab, an operation device with a display carried by a driver or an examination or inspection worker (operator), or the operation board  6  to be able to notify the driver or the examination or inspection worker (operator). 
         [0055]    Accordingly, the driver or worker can easily recognize the occurrence of miswire. 
         [0056]    In the above description, although only the single circuit is provided, which includes the current-limiting resistor  11 , the contactor  12 , the current-limiting resistance contactor  13 , the converter  14 , the inverter  15 , the current sensor unit  16 , the first motor  18   a,  the second motor  18   b,  and the controller  100 , a plurality of circuits can be also provided in the transformer  10 . 
         [0057]    While certain embodiments have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the inventions. Indeed, the novel embodiments described herein may be embodied in a variety of other forms; furthermore, various omissions, substitutions and changes in the form of the embodiments described herein may be made without departing from e spirit of the inventions. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the inventions.
An electric vehicle control device includes: a plurality of motors capable of transmitting motive power to a wheel of an electric vehicle; an inverter that supplies electric power to drive the motors; and a controller that controls the inverter and compares, when the electric vehicle drives under a certain velocity condition, a q-axis voltage feedforward value VqFF and a q-axis voltage command value Vq* used for controlling driving of the motors, to detect an occurrence of miswire between the motors and the inverter when the following inequation is satisfied: VqFF>=1.5*Vq*.