Patent Publication Number: US-10309842-B2

Title: Magnet temperature estimation device for rotating electric machine and magnet temperature estimation method for rotating electric machine

Description:
TECHNICAL FIELD 
     The present invention relates to a magnet temperature estimation device for a rotating electric machine and a magnet temperature estimation method for a rotating electric machine. 
     Priority is claimed on Japanese Patent Application No. 2014-098125, filed May 9, 2014, the contents of which are incorporated herein by reference. 
     BACKGROUND ART 
     In the related art, a motor control device configured to calculate a magnet temperature on the basis of a stator coil temperature, a liquid temperature of a cooling liquid, a heat generating ratio and a heat resistance ratio during operation of a motor is known (for example, see Patent Document 1). The motor control device previously acquires a ratio of a heat resistance between a cooling liquid and a stator coil and a heat resistance between the stator coil and a permanent magnet as a heat resistance ratio, and acquires a ratio of heat generation of the stator coil and heat generation of the permanent magnet as a heat generation ratio. 
     PRIOR ART DOCUMENTS 
     Patent Documents 
     Patent Document 1: Japanese Patent No. 4572907 
     SUMMARY OF INVENTION 
     Problems to be Solved by the Invention 
     However, according to the motor control device in the related art, a liquid temperature of a cooling liquid flowing toward the outside from an inside of the motor is detected outside the motor, and a heat resistance ratio is acquired on the basis of results of experiments that are previously performed. For this reason, a calculation error of a magnet temperature may be increased according to such as a flowing path and a cooling state of the cooling liquid inside the motor. 
     In consideration of the above-mentioned circumstances, an object of an aspect of the present invention is to provide a magnet temperature estimation device for a rotating electric machine and a magnet temperature estimation method for a rotating electric machine that are capable of improving estimation precision of the magnet temperature of a rotating electric machine. 
     Means for Solving the Problems 
     In order to solve the above-mentioned problems and accomplish the above-mentioned purposes, the present invention employs the following aspects. 
     (1) A magnet temperature estimation device for a rotating electric machine according to an aspect of the present invention includes a rotating electric machine configured with a rotor having a magnet and a stator having a coil; a coolant supply part configured to supply a coolant flowing from the stator toward the rotor; and a magnet temperature calculation part configured to calculate a temperature of the magnet using a temperature of the coolant has that received heat from the coil. 
     (2) In the aspect of the above mentioned (1), the magnet temperature calculation part may calculate a heat resistance of at least a portion between the magnet and the coolant that has received heat from the coil, calculate a heat reduction amount from the magnet using the heat resistance and a temperature of the coolant that has received heat from the coil, and calculate the temperature of the magnet using the heat reduction amount from the magnet. 
     (3) In the aspect of the above mentioned (2), the magnet temperature calculation part may calculate the heat resistance in accordance with a flow rate of the coolant and number of revolutions of the rotating electric machine. 
     (4) In the aspect of the above mentioned (2) or (3), a heating value calculation part configured to calculate a heating value due to loss of the magnet may be provided, and the magnet temperature calculation part may calculate the temperature of the magnet using the heating value due to the loss of the magnet and the heat reduction amount from the magnet. 
     (5) In any one aspect of the above mentioned (1) to (4), a coolant temperature calculation part configured to calculate the temperature of the coolant that has received heat from the coil may be provided, and the coolant temperature calculation part may acquire a beat receiving amount of the coolant that has received heat from the coil and a heat capacity of the coolant in accordance with the flow rate of the coolant, and calculate the temperature of the coolant that has received beat from the coil using the heat receiving amount of the coolant that has received heat from the coil and the heat capacity of the coolant. 
     (6) In the aspect of the above mentioned (5), a cooling part configured to cool the coolant may be provided, and the coolant temperature calculation part may acquire a heat resistance between the coil and the coolant that has received heat from the coil in accordance with the flow rate of the coolant, and calculate the heat receiving amount of the coolant that has received heat from the coil using the heat resistance between the coil and the coolant that has received heat from the coil, the temperature of the coil, and a temperature of the coolant cooled by the cooling part. 
     (7) A magnet temperature estimation method for a rotating electric machine is performed by a control device with respect to: a rotating electric machine configured with a rotor having a magnet and a stator having a coil, and a coolant supply part configured to supply a coolant flowing from the stator toward the rotor, and the magnet temperature estimation method for a rotating electric machine includes calculating a temperature of the magnet using a temperature of a coolant that has received heat from the coil. 
     Advantageous Effects of Invention 
     The magnet temperature estimation device for a rotating electric machine according to the aspect of the above mentioned (1) includes the magnet temperature calculation part configured to calculate the temperature of the magnet using the temperature of the coolant after the coolant flowing from the stator toward the rotor has received heat from the coil. For this reason, the calculation precision of the temperature of the magnet can be improved. In addition, the magnet temperature estimation device for a rotating electric machine according to the aspect of the above mentioned (1) includes the magnet temperature calculation part using a heat model in which the coolant that receives heat from the coil cools the magnet. For this reason, the temperature of the magnet can be precisely calculated according to a cooling path of the coolant in the rotating electric machine and a cooling state of the coil and the magnet by the coolant. 
     Further, in the aspect of the above mentioned (2), the magnet temperature calculation part configured to calculate the heat resistance of at least a portion between the magnet and the coolant that has received heat from the coil and configured to calculate the heat reduction amount from the magnet using the heat resistance may be provided. For this reason, the heat radiation amount from the magnet due to the coolant can be precisely calculated. 
     Further, in the aspect of the above mentioned (3), the magnet temperature calculation part configured to calculate the heat resistance of at least a portion between the magnet and the coolant that has received heat from the coil in accordance with the flow rate of the coolant and the number of revolutions of the rotating electric machine. For this reason, the heat resistance can be precisely calculated according to a state of the coolant in the rotor. 
     Further, in the aspect of the above mentioned (4), the magnet temperature calculation part configured to calculate the temperature of the magnet using the heating value due to loss of the magnet and the heat reduction amount from the magnet may be provided. For this reason, the temperature variation of the magnet according to a difference between the beating value and the heat reduction amount can be precisely calculated. 
     Further, in the aspect of the above mentioned (5), the coolant temperature calculation part configured to acquire the heat receiving amount of the coolant that has received heat from the coil and the heat capacity of the coolant in accordance with the flow rate of the coolant may be provided. For this reason, the temperature of the coolant can be precisely calculated according to a state (a contact state or the like) of the coolant that receives heat from the coil in the rotor. 
     Further, in the aspect of the above mentioned (6), the coolant temperature calculation part configured to acquire the heat resistance between the coil and the coolant that has received heat from the coil in accordance with the flow rate of the coolant may be provided. For this reason, the heat resistance can be precisely calculated according to a state of the coolant in the coil. 
     In the magnet temperature estimation method for a rotating electric machine according to the aspect of the above mentioned (7), the magnet temperature calculation part configured to calculate the temperature of the magnet using the temperature of the coolant after the coolant flowing from the stator toward the rotor receives heat from the coil may be provided. For this reason, the calculation precision of the temperature of the magnet can be improved. In addition, the magnet temperature estimation method for a rotating electric machine according to the aspect of the above mentioned (7) includes the magnet temperature calculation part using a heat model in which the coolant that receives heat from the coil cools the magnet. For this reason, the temperature of the magnet can be precisely calculated according to a cooling path of the coolant in the rotating electric machine and a cooling state of the coil and the magnet due to the coolant. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a view showing a configuration of a magnet temperature estimation device for a rotating electric machine according to an embodiment of the present invention. 
         FIG. 2  is a cross-sectional view showing a partial configuration of a driving motor of the magnet temperature estimation device for a rotating electric machine according to the embodiment of the present invention. 
         FIG. 3  is a view schematically showing a heat model of the magnet temperature estimation device for a rotating electric machine according to the embodiment of the present invention. 
         FIG. 4  is a view showing an interrelation between an applied voltage, the number of revolutions, torque and an iron loss of a rotor yoke in the driving motor of the magnet temperature estimation device for a rotating electric machine according to the embodiment of the present invention. 
         FIG. 5  is a view showing an interrelation between an applied voltage, the number of revolutions, torque and an eddy current loss of a magnet in the driving motor of the magnet temperature estimation device for a rotating electric machine according to the embodiment of the present invention. 
         FIG. 6  is a view showing an interrelation between the number of revolutions of a generating motor and a flow rate of a coolant of the magnet temperature estimation device for a rotating electric machine according to the embodiment of the present invention. 
         FIG. 7  is a view showing an interrelation of a flow rate of a coolant and heat resistance between a dropped coolant and a 3-phase coil in the driving motor of the magnet temperature estimation device for a rotating electric machine according to the embodiment of the present invention. 
         FIG. 8  is a view showing an interrelation of heat resistance between a dropped coolant and an end surface plate, a flow rate of a coolant, and the number of revolutions in the driving motor of the magnet temperature estimation device for a rotating electric machine according to the embodiment of the present invention. 
         FIG. 9  is a flowchart showing an operation of the magnet temperature estimation device for a rotating electric machine according to the embodiment of the present invention. 
         FIG. 10  is a flowchart showing one heating value calculation processing shown in  FIG. 9 . 
         FIG. 11  is a flowchart showing another heating value calculation processing shown in  FIG. 9 . 
         FIG. 12  is a flowchart showing dropped coolant temperature calculation processing shown in  FIG. 9 . 
         FIG. 13  is a flowchart showing heat resistance calculation processing shown in  FIG. 9 . 
         FIG. 14  is a flowchart showing magnet temperature calculation processing shown in  FIG. 9 . 
     
    
    
     DESCRIPTION OF EMBODIMENT 
     Hereinafter, a magnet temperature estimation device for a rotating electric machine and a magnet temperature estimation method for a rotating electric machine according to an embodiment of the present invention will be described with reference to the accompanying drawings. 
     A magnet temperature estimation device  10  for a rotating electric machine according to the embodiment is mounted on a vehicle  1  such as a hybrid vehicle, an electrically driven vehicle, or the like. As shown in  FIG. 1 , the vehicle  1  includes a driving motor (M)  11  (a rotating electric machine), a generating motor (G)  12 , a transmission (T/M)  13 , a coolant circulation section  14  (a coolant supply part), a power conversion part  15 , a battery  16 , and a control device  17 . 
     Each of the driving motor  11  and the generating motor  12  is, for example, a 3-phase alternating brushless DC motor, or the like. Each of the driving motor  11  and the generating motor  12  includes a rotary shaft connected to the transmission  13 . The rotary shaft of the generating motor  12  is connected to a mechanical pump of the coolant circulation section  14 , which will be described below. 
     As shown in  FIG. 2 , the driving motor  11  includes a stator  22  having a coil  21 , and a rotor  24  having a magnet  23 . The driving motor  11  is an inner rotor type and includes the rotor  24  in the stator  22  having a cylindrical shape. 
     The coil  21  is, for example, a segment conductor (SC) winding, or the like. The coil  21  is mounted in a slot formed between teeth of a stator core  22   a . The coil  21  is connected to the power conversion part  15 , which will be described below. The magnet  23  is, for example, a permanent magnet or the like. 
     The magnet  23  is held in a rotor yoke  24   a  not to come into direct contact with a pair of end surface plates  24   b  that sandwich the rotor yoke  24   a  from both sides in an axial direction of a rotary shaft  24   c.    
     The generating motor  12  includes, for example, the same configuration as the driving motor  11 . 
     The transmission  13  is, for example, an automatic transmission (AT) or the like. The transmission  13  is connected to the driving motor  11 , the generating motor  12  and driving wheels W. The transmission  13  controls power transmission between the driving wheels W and each of the driving motor  11  and the generating motor  12  according to a control signal output from the control device  17 , which will be described below. 
     The coolant circulation section  14  includes a coolant flow path  14   a  through which coolant circulates, and a cooler  14   b  (a cooling part) configured to cool the coolant. The coolant circulation section  14  uses, for example, working oil for performing lubrication, power transmission, and so on in the transmission  13  of the automatic transmission (AT) as coolant. 
     The coolant flow path  14   a  is connected to a flow path of the working oil in the transmission  13  and an inside of each of the driving motor  11  and the generating motor  12 . The coolant flow path  14   a  includes an ejection port (not shown) configured to eject coolant to each of the driving motor  11  and the generating motor  12 , and a suction port (not shown) configured to suction the coolant flowing through the inside of each of the driving motor  11  and the generating motor  12 . 
     The ejection port of the coolant flow path  14   a  is disposed over each of the driving motor  11  and the generating motor  12  in a vertical direction. The suction port of the coolant flow path  14   a  is disposed at a coolant storage section (not shown) formed under each of the driving motor  11  and the generating motor  12  in the vertical direction. 
     The cooler  14   b  includes a mechanical pump installed at the coolant flow path  14   a  and connected to the rotary shaft of the generating motor  12 . The mechanical pump generates a suction force by driving of the generating motor  12  and causes the coolant in the coolant flow path  14   a  to flow toward the ejection port while suctioning the coolant from the suction port of the coolant flow path  14   a . The cooler  14   b  cools the coolant flowing through the coolant flow path  14   a.    
     The coolant circulation section  14  ejects the coolant from the ejection part of the coolant flow path  14   a  toward a coil end of the coil  21  (a portion protruding outward from a slot of the stator core  22   a  in an axial direction thereof) according to an operation of the mechanical pump of the cooler  14   b  with respect to the driving motor  11 . 
     The coolant flows downward in the vertical direction on the coil end of the coil  21  and a surface of the stator core  22   a  by an action of gravity. The coolant flows downward in the vertical direction such that the coolant is dropped from the coil end of the coil  21  or the stator core  22   a  onto the end surface plates  24   b  via a gap between the stator  22  and the rotor  24  by the action of gravity. The coolant (dropped coolant) dropped on the surfaces of the end surface plates  24   b  flows on the surfaces of the end surface plates  24   b  to an outside of the end surface plates  24   b  by a centrifugal force due to a rotation of the rotor  24  and the action of gravity. The dropped coolant flows into the coolant storage section from the outside of the end surface plates  24   b  by the action of gravity. 
     The coolant circulation section  14  suctions the coolant stored in the coolant storage section from the suction port into the coolant flow path  14   a  by a suction of the mechanical pump, and performs cooling by the cooler  14   b . Accordingly, as shown in  FIG. 3 , the coolant circulation section  14  cools the coil  21  and the stator core  22   a  using the coolant. The coolant circulation section  14  directly cools the end surface plates  24   b  using the dropped coolant, and indirectly and sequentially cools the rotor yoke  24   a  and the magnet  23  via the end surface plates  24   b  using the dropped coolant. 
     The power conversion part  15  includes a booster  31  configured to increase an output voltage of the battery  16 , a second power drive unit (PDU 2 )  33  configured to control electrical conduction of the driving motor  11 , and a first power drive unit (PDU 1 )  32  configured to control electrical conduction of the generating motor  12 . 
     The booster  31  includes, for example, a DC-DC converter or the like. The booster  31  is connected between the battery  16  and the first and second power drive units  32  and  33 . 
     The booster  31  generates a voltage applied to the first and second power drive units  32  and  33  by increasing an output voltage of the battery  16  according to a control signal output from the control device  17 , which will be described below. The booster  31  outputs the applied voltage generated by increasing the output voltage of the battery  16  to the first and second power drive units  32  and  33 . 
     The first and second power drive units  32  and  33  include, for example, inverter devices or the like. The first and second power drive units  32  and  33  include bridge circuits and smoothing condensers formed by, for example, bridging and connecting a plurality of switching elements (for example, MOSFETs or the like) as inverter devices. The first and second power drive units  32  and  33  convert direct current output power of the booster  31  into 3-phase alternating current power according to a control signal output from the control device  17 , which will be described below. The first power drive unit  32  electrically conducts a 3-phase alternating current to the 3-phase coil  21  such that electrical conduction to the generating motor  12  is sequentially conmmutated. In addition, the second power drive unit  33  electrically conducts a 3-phase alternating current to the 3-phase coil  21  such that electrical conduction to the driving motor  11  is sequentially commutated. 
     The control device  17  is configured with a central processing unit (CPU), various storage media such as a random access memory (RAM) or the like, and an electronic circuit such as a timer or the like. The control device  17  outputs a control signal to control the transmission  13  and the power conversion part  15 . The control device  17  is connected to a voltage sensor  41 , a first current sensor  42 , a second current sensor  43 , a first number-of-revolutions sensor  44 , a second number-of-revolutions sensor  45 , a torque sensor  46 , a coolant temperature sensor  47  and a coil temperature sensor  48 . 
     The voltage sensor  41  detects the applied voltage applied to each of the first and second power drive units  32  and  33  from the booster  31 . The first current sensor  42  detects an alternating current (a phase current) flowing between the first power drive unit  32  and each of the coil  21  of the generating motor  12 . The second current sensor  43  detects an alternating current (a phase current) flowing between the second power drive unit  33  and each of the coil  21  of the driving motor  11 . 
     The first number-of-revolutions sensor  44  detects the number of revolutions of the driving motor  11  by sequentially detecting the rotation angle of the rotary shaft of the driving motor  11 . The second number-of-revolutions sensor  45  detects the number of revolutions of the generating motor  12  by sequentially detecting the rotation angle of the rotary shaft of the generating motor  12 . 
     The torque sensor  46  detects torque of the driving motor  11 . The coolant temperature sensor  47  detects the temperature of the coolant output from the cooler  14   b  in the coolant flow path  14   a  (the coolant temperature after passing through the cooler). 
     The coil temperature sensor  48  is, for example, a thermistor or the like, and detects a temperature of the coil  21  of the driving motor  11  (a coil temperature). 
     As shown in  FIG. 1 , the control device  17  includes a heating value calculation part  51 , a dropped coolant temperature calculation part  52 , a magnet temperature calculation part  53 , a motor controller  54  and a storage  55 . 
     The heating value calculation part  51  calculates a heating value due to a loss of each part in each of the driving motor  11  and the generating motor  12 . For example, the heating value calculation part  51  calculates heating values of a copper loss of the 3-phase coil  21 , an iron loss of the rotor yoke  24   a  and an eddy current loss of the magnet  23  in the driving motor  11 . 
     The heating value calculation part  51  calculates the copper loss of the 3-phase coil  21  according to a 3-phase phase current of the driving motor  11  detected by the second current sensor  43  and a resistance value of the 3-phase coil  21  previously stored in the storage  55 . 
     The heating value calculation part  51  calculates an iron loss W YOKE  of the rotor yoke  24   a  according to the applied voltage detected by the voltage sensor  41 , the number of revolutions of the driving motor  11  detected by the first number-of-revolutions sensor  44 , and the torque of the driving motor  11  detected by the torque sensor  46 . As shown in  FIG. 4 , the heating value calculation part  51  previously stores data such as a map or the like showing a mutual relationship between the applied voltage, the number of revolutions, the torque, and the iron loss W YOKE  of the rotor yoke  24   a  in the storage  55 . The heating value calculation part  51  calculates the iron loss W YOKE  of the rotor yoke  24   a  with reference to the data previously stored in the storage  55  using the applied voltage, the number of revolutions and the torque detected by the sensors  41 ,  44  and  46 . The heating value calculation part  51  calculates the iron loss W YOKE  while performing linear interpolation or the like with respect to the applied voltage and the number of revolutions, for example, using the map showing the mutual relationship between the torque and the iron loss W YOKE  with respect to combinations of a plurality of different applied voltages (Va&lt;Vb) and the numbers of revolutions (N1&lt;N2&lt;N3). 
     The heating value calculation part  51  calculates the eddy current loss W MAG  of the magnet  23  according to the applied voltage detected by the voltage sensor  41 , the number of revolutions of the driving motor  11  detected by the first number-of-revolutions sensor  44 , and the torque of the driving motor  11  detected by the torque sensor  46 . As shown in  FIG. 5 , the heating value calculation part  51  previously stores data such as the map or the like showing the mutual relationship between the applied voltage, the number of revolutions, the torque, and the eddy current loss W MAG  of the magnet  23  in the storage  55 . The heating value calculation part  51  calculates the eddy current loss W MAG  of the magnet  23  with reference to the data previously stored in the storage  55  using the applied voltage, the number of revolutions and the torque detected by the sensors  41 ,  44  and  46 . The heating value calculation part  51  calculates the eddy current loss W MAG  while performing linear interpolation or the like with respect to the applied voltage and the number of revolutions, for example, using the map showing the mutual relationship between the torque and the eddy current loss W MAG  with respect to combinations of the plurality of different applied voltages (Va&lt;Vb) and the numbers of revolutions (N1&lt;N2&lt;N3). 
     The dropped coolant temperature calculation part  52  calculates a temperature T DATF  of the dropped coolant according to the coolant temperature after passing through the cooler detected by the coolant temperature sensor  47 , the number of revolutions of the generating motor  12  detected by the second number-of-revolutions sensor  45 , and the coil temperature detected by the coil temperature sensor  48 . 
     The dropped coolant temperature calculation part  52  acquires a flow rate of the coolant circulating in the coolant circulation section  14  according to the number of revolutions of the generating motor  12  detected by the second number-of-revolutions sensor  45 . As shown in  FIG. 6 , the dropped coolant temperature calculation part  52  previously stores data such as a map or the like showing a mutual relationship between the number of revolutions of the generating motor  12  and the flow rate of the coolant in the storage  55 . The dropped coolant temperature calculation part  52  calculates the flow rate of the coolant with reference to the data previously stored in the storage  55  using the number of revolutions detected by the second number-of-revolutions sensor  45 . 
     The dropped coolant temperature calculation part  52  calculates a heat receiving amount Q co-atf  of the dropped coolant from the 3-phase coil  21  according to the coolant temperature after passing through the cooler detected by the coolant temperature sensor  47 , the coil temperature detected by the coil temperature sensor  48 , and the flow rate of the coolant. 
     As shown in  FIG. 7 , the dropped coolant temperature calculation part  52  previously stores data such as a map or the like showing a mutual relationship between a heat resistance R co-atf  between the dropped coolant and the 3-phase coil  21 , and the flow rate of the coolant in the storage  55 . The dropped coolant temperature calculation part  52  calculates the heat resistance R co-atf  between the dropped coolant and the 3-phase coil  21  with reference to the data previously stored in the storage  55  using the calculated flow rate of the coolant. 
     The dropped coolant temperature calculation part  52  calculates the heat receiving amount Q co-atf  using the calculated heat resistance R co-atf , a coolant temperature T atf  after passing through the cooler and a coil temperature T co  as expressed in the following Equation (1). 
     
       
         
           
             
               
                 
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     The dropped coolant temperature calculation part  52  calculates the temperature T DATF  of the dropped coolant according to the calculated heat receiving amount Q co-atf , a heat capacity of the coolant and the coolant temperature T atf  after passing through the cooler. 
     As expressed in the following Equation (2), the dropped coolant temperature calculation part  52  calculates a heat capacity C atf  of the coolant using a calculated flow rate F atf  of the coolant and a specific heat C and a predetermined coefficient A of the coolant previously stored in the storage  55 . 
     The dropped coolant temperature calculation part  52  calculates a temperature variation ΔT atf  of the coolant using the calculated heat receiving amount Q co-atf  and the heat capacity C atf  of the coolant. 
     As expressed in the following Equation (3), the dropped coolant temperature calculation part  52  calculates the temperature T DATF  of the dropped coolant using the calculated temperature variation ΔT atf  of the coolant and the coolant temperature T atf  after passing through the cooler. 
     
       
         
           
             
               
                 
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     The magnet temperature calculation part  53  calculates a heat resistance R EP-DATF  between the dropped coolant and the end surface plates  24   b  according to the number of revolutions of the driving motor  11  detected by the first number-of-revolutions sensor  44  and the flow rate F atf  of the coolant calculated by the dropped coolant temperature calculation part  52 . As shown in  FIG. 8 , the magnet temperature calculation part  53  previously stores a map or the like showing a mutual relationship between the heat resistance R EP-DATF  between the dropped coolant and the end surface plates  24   b , the flow rate F atf  of the coolant, and the number of revolutions of the driving motor  11  in the storage  55 . The magnet temperature calculation part  53  calculates the heat resistance R EP-DATF  between the dropped coolant and the end surface plates  24   b  with reference to the data previously stored in the storage  55  using the flow rate F atf  of the coolant and the number of revolutions of the driving motor  11 . The magnet temperature calculation part  53  calculates the heat resistance R EP-DATF  while performing linear interpolation or the like with respect to the flow rate F atf , for example, using a map or the like showing a mutual relationship between the number of revolutions and the heat resistance R EP-DATF  with respect to flow rates F atf  (F1&lt;F2&lt;F3&lt;F4) of a plurality of different coolants. 
     The magnet temperature calculation part  53  calculates a temperature T MAG  of the magnet  23  according to the calculated heat resistance R EP-DATF , the temperature T DATF  of the dropped coolant calculated by the dropped coolant temperature calculation part  52 , the iron loss W YOKE  of the rotor yoke  24   a  and the eddy current loss W MAG  of the magnet  23  calculated by the heating value calculation part  51 . 
     As expressed in the following Equation (4), the magnet temperature calculation part  53  calculates the temperature T EP  of the end surface plates  24   b  using a last count temperature T EP (pre) of the end surface plates  24   b  stored in the storage  55  and a temperature variation ΔT EP  of the end surface plates  24   b . The magnet temperature calculation part  53  estimates the temperature variation ΔT EP  of the end surface plates  24   b  by, for example, an appropriate calculation or the like.
 
[Math. 4]
 
 T   EP   =T   EP (pre)+Δ T   EP   (4)
 
     As expressed in the following Equation (5), the magnet temperature calculation part  53  calculates a heat receiving amount Q EP-DATF  of the dropped coolant from the end surface plates  24   b  using the heat resistance R EP-DATF  between the calculated dropped coolant and the end surface plates  24   b , the temperature T EP  of the end surface plates  24   b , and the temperature T DATF  of the dropped coolant. 
     As expressed in the following Equation (6), the magnet temperature calculation part  53  finds that a heat receiving amount Q YOKE-EP  of the end surface plates  24   b  from the rotor yoke  24   a  is equal to the heat receiving amount Q EP-DATF  of the dropped coolant from the end surface plates  24   b . 
     
       
         
           
             
               
                 
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                         - 
                       
                       ⁢ 
                       DATF 
                     
                   
                   = 
                   
                     
                       
                         T 
                         EP 
                       
                       - 
                       
                         T 
                         DATF 
                       
                     
                     
                       R 
                       
                         EP 
                         ⁢ 
                         
                           - 
                         
                         ⁢ 
                         DATF 
                       
                     
                   
                 
               
               
                 
                   ( 
                   5 
                   ) 
                 
               
             
             
               
                 
                   [ 
                   
                     Math 
                     . 
                     
                         
                     
                     ⁢ 
                     6 
                   
                   ] 
                 
               
               
                 
                     
                 
               
             
             
               
                 
                   
                     Q 
                     
                       YOKE 
                       ⁢ 
                       
                         - 
                       
                       ⁢ 
                       EP 
                     
                   
                   = 
                   
                     Q 
                     
                       EP 
                       ⁢ 
                       
                         - 
                       
                       ⁢ 
                       DATF 
                     
                   
                 
               
               
                 
                   ( 
                   6 
                   ) 
                 
               
             
           
         
       
     
     The magnet temperature calculation part  53  calculates a heat receiving amount Q MAG-YOKE  of the rotor yoke  24   a  from the magnet  23  using a last count temperature T MAG (pre) of the magnet  23  and a heat resistance R MAG-YOKE  between the rotor yoke  24   a  and the magnet  23  stored in the storage  55 , and an estimated temperature T YOKE (est) of the rotor yoke  24   a . The magnet temperature calculation part  53  calculates the heat receiving amount Q MAG-YOKE  by dividing a difference between the estimated value T YOKE (est) and the last count T MAG (pre) by the heat resistance R MAG-YOKE . 
     The magnet temperature calculation part  53  stores, for example, a predetermined constant value serving as the heat resistance R MAG-YOKE  between the rotor yoke  24   a  and the magnet  23  in the storage  55 . The magnet temperature calculation part  53  estimates an estimated value T YOKE (est) of the temperature of the rotor yoke  24   a  by, for example, an appropriate calculation or the like. 
     As expressed in the following Equation (7), the magnet temperature calculation part  53  calculates a heat receiving amount Q YOKE  of the rotor yoke  24   a  using the calculated heat receiving amount Q YOKE-EP  of the end surface plates  24   b  from the rotor yoke  24   a , the calculated heat receiving amount Q MAG-YOKE  of the rotor yoke  24   a  from the magnet  23  and the iron loss W YOKE  of the rotor yoke  24   a.  
 
[Math. 7]
 
 Q   YOKE   =W   YOKE   +Q   MAG-YOKE   −Q   YOKE-EP   (7)
 
     As expressed in the following Equation (8), the magnet temperature calculation part  53  calculates a temperature variation ΔT YOKE  of the rotor yoke  24   a  using a heat capacity C YOKE  of the rotor yoke  24   a  stored in the storage  55  and the calculated heat receiving amount Q YOKE  of the rotor yoke  24   a.    
     As expressed in the following Equation (9), the magnet temperature calculation part  53  calculates a temperature T YOKE  of the rotor yoke  24   a  using a last count temperature T YOKE (pre) of the rotor yoke  24   a  stored in the storage  55  and the calculated temperature variation ΔT YOKE  of the rotor yoke  24   a . 
     
       
         
           
             
               
                 
                   [ 
                   
                     Math 
                     . 
                     
                         
                     
                     ⁢ 
                     8 
                   
                   ] 
                 
               
               
                 
                     
                 
               
             
             
               
                 
                   
                     Δ 
                     ⁢ 
                     
                         
                     
                     ⁢ 
                     
                       T 
                       YOKE 
                     
                   
                   = 
                   
                     
                       Q 
                       YOKE 
                     
                     
                       C 
                       YOKE 
                     
                   
                 
               
               
                 
                   ( 
                   8 
                   ) 
                 
               
             
             
               
                 
                   [ 
                   
                     Math 
                     . 
                     
                         
                     
                     ⁢ 
                     9 
                   
                   ] 
                 
               
               
                 
                     
                 
               
             
             
               
                 
                   
                     T 
                     YOKE 
                   
                   = 
                   
                     
                       
                         T 
                         YOKE 
                       
                       ⁡ 
                       
                         ( 
                         pre 
                         ) 
                       
                     
                     + 
                     
                       Δ 
                       ⁢ 
                       
                           
                       
                       ⁢ 
                       
                         T 
                         YOKE 
                       
                     
                   
                 
               
               
                 
                   ( 
                   9 
                   ) 
                 
               
             
           
         
       
     
     As expressed in the following Equation (10), the magnet temperature calculation part  53  calculates a heat reduction amount (that is, a heat radiation amount) Q MAG  from the magnet  23  using the last count temperature T MAG (pre) of the magnet  23  and the heat resistance R MAG-YOKE  between the rotor yoke  24   a  and the magnet  23  stored in the storage  55 , and the calculated temperature T YOKE  of the rotor yoke  24   a.    
     As expressed in the following Equation (1), the magnet temperature calculation part  53  calculates a temperature variation ΔT MAG  of the magnet  23  using a heat capacity C MAG  of the magnet  23  stored in the storage  55 , the calculated heat reduction amount Q MAG , and the eddy current loss W MAG  of the magnet  23 . 
     As expressed in the following Equation (12), the magnet temperature calculation part  53  calculates the temperature T MAG  of the magnet  23  using the last count temperature T MAG (pre) of the magnet  23  stored in the storage  55  and the calculated temperature variation ΔT MAG  of the magnet  23 . 
     
       
         
           
             
               
                 
                   [ 
                   
                     Math 
                     . 
                     
                         
                     
                     ⁢ 
                     10 
                   
                   ] 
                 
               
               
                 
                     
                 
               
             
             
               
                 
                   
                     Q 
                     MAG 
                   
                   = 
                   
                     
                       
                         
                           T 
                           MAG 
                         
                         ⁡ 
                         
                           ( 
                           pre 
                           ) 
                         
                       
                       - 
                       
                         T 
                         YOKE 
                       
                     
                     
                       R 
                       
                         MAG 
                         ⁢ 
                         
                           - 
                         
                         ⁢ 
                         YOKE 
                       
                     
                   
                 
               
               
                 
                   ( 
                   10 
                   ) 
                 
               
             
             
               
                 
                   [ 
                   
                     Math 
                     . 
                     
                         
                     
                     ⁢ 
                     11 
                   
                   ] 
                 
               
               
                 
                     
                 
               
             
             
               
                 
                   
                     Δ 
                     ⁢ 
                     
                         
                     
                     ⁢ 
                     
                       T 
                       MAG 
                     
                   
                   = 
                   
                     
                       ( 
                       
                         
                           W 
                           MAG 
                         
                         - 
                         
                           Q 
                           MAG 
                         
                       
                       ) 
                     
                     
                       C 
                       MAG 
                     
                   
                 
               
               
                 
                   ( 
                   11 
                   ) 
                 
               
             
             
               
                 
                   [ 
                   
                     Math 
                     . 
                     
                         
                     
                     ⁢ 
                     12 
                   
                   ] 
                 
               
               
                 
                     
                 
               
             
             
               
                 
                   
                     T 
                     MAG 
                   
                   = 
                   
                     
                       
                         T 
                         MAG 
                       
                       ⁡ 
                       
                         ( 
                         pre 
                         ) 
                       
                     
                     + 
                     
                       Δ 
                       ⁢ 
                       
                           
                       
                       ⁢ 
                       
                         T 
                         MAG 
                       
                     
                   
                 
               
               
                 
                   ( 
                   12 
                   ) 
                 
               
             
           
         
       
     
     The motor controller  54  controls the driving motor  11  and the generating motor  12  by outputting a control signal for controlling the transmission  13  and the power conversion part  15  on the basis of the temperature T MAG  of the magnet  23  calculated by the magnet temperature calculation part  53 . 
     The magnet temperature estimation device  10  for a rotating electric machine according to the present embodiment includes the above-mentioned configuration, and an operation of the magnet temperature estimation device  10  for a rotating electric machine, i.e., the magnet temperature estimation method for a rotating electric machine, will be described. 
     Hereinafter, processing in which the control device  17  calculates the temperature T MAG  of the magnet  23  of the driving motor  11  and controls the driving motor  11  will be described. 
     First, as shown in  FIG. 9 , the control device  17  calculates a heating value due to loss of respective parts of the driving motor  11  (step S 01 ). 
     Next, the control device  17  calculates the temperature T DATF  of dropped coolant (step S 02 ). 
     Next, the control device  17  calculates the heat resistance R EP-DATF  between the dropped coolant and the end surface plates  24   b  (step S 03 ). 
     Next, the control device  17  calculates the temperature T MAG  of the magnet  23  (step S 04 ). 
     Next, the control device  17  determines whether the calculated temperature T MAG  of the magnet  23  is less than a predetermined output limit temperature (step SOS). 
     When the determination result is “YES,” the control device  17  terminates the processing without performing output limitation of the driving motor  11  (YES in step S 05 ). 
     On the other hand, when the determination result is “NO,” the control device  17  advances the processing to step S 06  (NO in step S 05 ). 
     Then, the control device  17  calculates an upper limit of allowable torque of the driving motor  11  (step S 06 ). 
     Next, the control device  17  outputs a control signal for instructing the power conversion part  15  to make the torque of the driving motor  11 I to the upper limit of allowable torque or less (step S 07 ). Then, the control device  17  terminates the processing. 
     Hereinafter, heating value calculation processing of the above-mentioned step S 01  will be described. 
     First, as shown in  FIG. 10 , the control device  17  acquires a 3-phase phase current of the driving motor  11  (i.e., an alternating current of the 3-phase coil  21 ) detected by the second current sensor  43  (step S 11 ). 
     Next, the control device  17  calculates a copper loss of the 3-phase coil  21  according to the acquired phase current of the 3-phase coil  21  and a resistance value of the 3-phase coil  21  previously stored in the storage  55  (step S 12 ). Then, the control device  17  terminates the processing. 
     In addition, as shown in  FIG. 11 , the control device  17  acquires the torque of the driving motor  11  detected by the torque sensor  46  (step S 21 ). 
     Next, the control device  17  acquires the number of revolutions of the driving motor  11  detected by the first number-of-revolutions sensor  44  (step S 22 ). 
     Next, the control device  17  acquires the applied voltage detected by the voltage sensor  41  (step S 23 ). 
     Next, the control device  17  calculates the iron loss W YOKE  of the rotor yoke  24   a  with reference to the data previously stored in the storage  55  using the torque, the number of revolutions and the applied voltage, which are acquired. Then, the control device  17  stores the calculated iron loss W YOKE  of the rotor yoke  24   a  in the storage  55  (step S 24 ). 
     Next, the control device  17  calculates the eddy current loss W MAG  of the magnet  23  with reference to the data previously stored in the storage  55  using the torque, the number of revolutions and the applied voltage, which are acquired. Then, the control device  17  stores the calculated eddy current loss W MAG  of the magnet  23  in the storage  55  (step S 25 ). Then, the control device  17  terminates the processing. 
     Hereinafter, dropped coolant temperature calculation processing of the above-mentioned step S 02  will be described. 
     First, as shown in  FIG. 12 , the control device  17  acquires the coolant temperature T atf  after passing through the cooler detected by the coolant temperature sensor  47  (step S 31 ). 
     Next, the control device  17  calculates the flow rate F atf  of the coolant with reference to the data previously stored in the storage  55  using the number of revolutions detected by the second number-of-revolutions sensor  45 . Alternatively, the flow rate F atf  of the coolant is acquired from a flow rate sensor or the like (step S 32 ). 
     Next, the control device  17  acquires the coil temperature T co , detected by the coil temperature sensor  48  (step S 33 ). 
     Next, the control device  17  calculates the heat resistance R co-atf  between the dropped coolant and the 3-phase coil  21  with respect to the data previously stored in the storage  55  using the flow rate F atf  of the coolant. Then, as expressed in the above-mentioned Equation (1), the control device  17  calculates the heat receiving amount Q co-atf  using the heat resistance R co-atf , the coolant temperature T atf  after passing through the cooler, and the coil temperature T co  (step S 34 ). 
     Next, as expressed in the above-mentioned Equation (2), the control device  17  calculates the heat capacity C atf  of the coolant using the flow rate F atf  of the coolant, and the specific heat C and the predetermined coefficient A of the coolant previously stored in the storage  55 . Then, the control device  17  calculates the temperature variation ΔT atf  of the coolant using the heat receiving amount Q co-atf  and the heat capacity C atf  of the coolant. Then, as expressed in the above-mentioned Equation (3), the control device  17  calculates the temperature T DATF  of the dropped coolant using the temperature variation ΔT atf  of the coolant and the coolant temperature T atf  after passing through the cooler. Then, the control device  17  stores the calculated temperature T DATF  of the dropped coolant in the storage  55  (step S 35 ). Then, the control device  17  terminates the processing. 
     Hereinafter, heat resistance calculation processing of the above-mentioned step S 03  will be described. 
     First, as shown in  FIG. 13 , the control device  17  acquires the number of revolutions of the driving motor  11  (step S 41 ). 
     Next, the control device  17  calculates or acquires the flow rate F atf  of the coolant (step S 42 ). 
     Next, the control device  17  calculates the heat resistance R EP-DATF  between the dropped coolant and the end surface plates  24   b  with reference to the data previously stored in the storage  55  using the flow rate F atf  of the coolant and the number of revolutions of the driving motor  11 . Then, the control device  17  stores the calculated heat resistance R EP-DATF  in the storage  55  (step S 43 ). 
     Next, the control device  17  acquires the heat resistance R MAG-YOKE  between the rotor yoke  24   a  and the magnet  23 , which is a predetermined constant value previously stored in the storage  55  (step S 44 ). 
     Then, the control device  17  terminates the processing. 
     Hereinafter, magnet temperature calculation processing of the above-mentioned step S 04  will be described. 
     First, as shown in  FIG. 14 , the control device  17  acquires the last count temperature T MAG (pre) of the magnet  23  stored in the storage  55  (step S 51 ). 
     Next, the control device  17  acquires the temperature T DATF  of the dropped coolant (step S 52 ). 
     Next, as expressed in the above-mentioned Equation (4), the control device  17  calculates the temperature T EP  of the end surface plates  24   b  using the last count temperature T EP (pre) of the end surface plates  24   b  stored in the storage  55  and the temperature variation ΔT EP  of the end surface plates  24   b . Then, the control device  17  stores the calculated temperature T EP  of the end surface plates  24   b  in the storage  55 . Then, as expressed in the above-mentioned Equation (5), the control device  17  calculates the heat receiving amount Q EP-DATF  of the dropped coolant from the end surface plates  24   b  using the heat resistance R EP-DATF  between the dropped coolant and the end surface plates  24   b , the temperature T EP  of the end surface plates  24   b , and the temperature T DATF  of the dropped coolant. Then, as expressed in the above-mentioned Equation (6), the control device  17  finds that the heat receiving amount Q YOKE-EP  of the end surface plates  24   b  from the rotor yoke  24   a  is equal to the heat receiving amount Q EP-DATF  of the dropped coolant from the end surface plates  24   b . Then, the control device  17  calculates the heat receiving amount Q MAG-YOKE  of the rotor yoke  24   a  from the magnet  23  using the last count temperature T MAG (pre) of the magnet  23  and the heat resistance R MAG-YOKE  between the rotor yoke  24   a  and the magnet  23  stored in the storage  55 , and the estimated temperature T YOKE (est) of the rotor yoke  24   a . Then, as expressed in the above-mentioned Equation (7), the control device  17  calculates the heat receiving amount Q YOKE  of the rotor yoke  24   a  using the heat receiving amount Q YOKE-EP  of the end surface plates  24   b  from the rotor yoke  24   a , the heat receiving amount Q MAG-YOKE  of the rotor yoke  24   a  from the magnet  23 , and the iron loss W YOKE  of the rotor yoke  24   a . Then, as expressed in the above-mentioned Equation (8), the control device  17  calculates the temperature variation ΔT YOKE  of the rotor yoke  24   a  using the heat capacity C YOKE  of the rotor yoke  24   a  stored in the storage  55  and the heat receiving amount Q YOKE  of the rotor yoke  24   a . Then, as expressed in the above-mentioned Equation (9), the control device  17  calculates the temperature T YOKE  of the rotor yoke  24   a  using the last count temperature T YOKE (pre) of the rotor yoke  24   a  stored in the storage  55  and the temperature variation ΔT YOKE  of the rotor yoke  24   a . Then, the control device  17  stores the calculated temperature T YOKE  of the rotor yoke  24   a  in the storage  55  (step S 53 ). 
     Next, as expressed in the above-mentioned Equation (10), the control device  17  calculates the heat reduction amount Q MAG  from the magnet  23  using the last count temperature T MAG (pre) of the magnet  23  and the heat resistance R MAG-YOKE  between the rotor yoke  24   a  and the magnet  23  stored in the storage  55 , and the temperature T YOKE  of the rotor yoke  24   a  (step S 54 ). 
     Next, as expressed in the above-mentioned Equation (11), the control device  17  calculates the temperature variation ΔT MAG  of the magnet  23  using the heat capacity C MAG  of the magnet  23  stored in the storage  55 , the heat reduction amount Q MAG , and the eddy current loss W MAG  of the magnet  23  (step S 55 ). 
     Next, as expressed in the above-mentioned Equation (12), the control device  17  calculates the temperature T MAG  of the magnet  23  using the last count temperature T MAG (pre) of the magnet  23  stored in the storage  55  and the temperature variation ΔT MAG  of the magnet  23  (step S 56 ). 
     Next, the control device  17  stores the calculated temperature T MAG  of the magnet  23  in the storage  55  (step S 57 ). Then, the control device  17  terminates the processing. 
     As described above, the magnet temperature estimation device  10  and the magnet temperature estimation method for a rotating electric machine according to the embodiment includes the magnet temperature calculation part  53  configured to calculate the temperature T MAG  of the magnet  23  using the temperature T DATF  of the dropped coolant. For this reason, calculation precision of the temperature T MAG  of the magnet  23  can be improved. 
     In addition, the magnet temperature estimation device  10  and the magnet temperature estimation method for a rotating electric machine according to the embodiment includes the magnet temperature calculation part  53  using a heat model in which the dropped coolant that receives heat from the coil  21  cools the magnet  23 . For this reason, the temperature T MAG  of the magnet  23  can be precisely calculated according to the cooling path of the coolant in the driving motor  11  and a cooling state of the coil  21  and the magnet  23 . 
     Further, the magnet temperature estimation device  10  and the magnet temperature estimation method for a rotating electric machine according to the embodiment includes the magnet temperature calculation part  53  configured to calculate the heat resistance R EP-DATF  between the dropped coolant and the end surface plates  24   b  and calculate the heat reduction amount Q MAG  from the magnet  23  using the heat resistance R EP-DATF . For this reason, a heat radiation amount from the magnet  23  due to the dropped coolant can be precisely calculated. 
     Further, the magnet temperature estimation device  10  and the magnet temperature estimation method for a rotating electric machine according to the embodiment includes the magnet temperature calculation part  53  configured to calculate the heat resistance R EP-DATF  between the dropped coolant and the end surface plates  24   b  according to the flow rate F atf  of the coolant and the number of revolutions of the driving motor  11 . For this reason, the heat resistance R EP-DATF  can be precisely calculated according to a state of the dropped coolant in the rotor  24 . 
     Further, the magnet temperature estimation device  10  and the magnet temperature estimation method for a rotating electric machine according to the embodiment includes the magnet temperature calculation part  53  configured to calculate the temperature T MAG  of the magnet  23  using the eddy current loss W MAG  of the magnet  23  and the heat reduction amount Q MAG  from the magnet  23 . For this reason, the temperature variation ΔT MAG  of the magnet  23  can be precisely calculated according to a difference between the heating value and a heat radiation amount due to loss of the magnet  23 . 
     Further, the magnet temperature estimation device  10  and the magnet temperature estimation method for a rotating electric machine according to the embodiment includes the dropped coolant temperature calculation part  52  configured to acquire the heat receiving amount Q co-atf  of the dropped coolant from the 3-phase coil  21  and the heat capacity C atf  of the coolant according to the flow rate F atf  of the coolant. For this reason, the temperature T DATF  of the dropped coolant can be precisely calculated according to a state (a contact state or the like) of the dropped coolant in the rotor  24 . 
     Further, the magnet temperature estimation device  10  and the magnet temperature estimation method for a rotating electric machine according to the embodiment includes the dropped coolant temperature calculation part  52  configured to acquire the beat resistance R co-atf  between the dropped coolant and the 3-phase coil  21  according to the flow rate F atf  the coolant. For this reason, the beat resistance R co-atf  can be precisely calculated according to a state of the coolant in the 3-phase coil  21 . 
     Further, in the above-mentioned embodiment, while the control device  17  calculates the heat reduction amount Q MAG  from the magnet  23  according to the holding of the magnet  23  in the rotor yoke  24   a  such that the magnet  23  in the driving motor  11  does not come into direct contact with the end surface plates  24   b , it is not limited thereto. For example, in the heat model shown in  FIG. 3 , the heat reduction amount Q MAG  from the magnet  23  may also be calculated to correspond to each of the cases in which the end surface plates  24   b , the rotor yoke  24   a , or the end surface plates  24   b  and the rotor yoke  24   a  are omitted. 
     For example, the case in which the magnet  23  in the driving motor  11  comes into direct contact with the end surface plates  24   b  to be held at the rotor yoke  24   a  corresponds to the case in which the rotor yoke  24   a  in the heat model shown in  FIG. 3  is omitted. 
     For example, the case in which the end surface plates  24   b  in the driving motor  11  are omitted and the dropped coolant comes into direct contact with the magnet  23  corresponds to the case in which the end surface plates  24   b  and the rotor yoke  24   a  in the heat model shown in  FIG. 3  are omitted. 
     For example, the case in which the end surface plates  24   b  in the driving motor  11  is omitted and the dropped coolant does not come into direct contact with the magnet  23  corresponds to the case in which the end surface plates  24   b  in the heat model shown in  FIG. 3  are omitted. 
     The control device  17  may calculate the heat reduction amount Q MAG  from the magnet  23  using the heat resistance and the heat receiving amount corresponding to each of the heat models. 
     Further, in the above-mentioned embodiment, the control device  17  acquires the flow rate of the coolant from the number of revolutions of the generating motor  12  because the mechanical pump of the coolant circulation section  14  is connected to the rotary shaft of the generating motor  12 , but it is not limited thereto. For example, when the coolant circulation section  14  includes a flow rate sensor configured to detect a flow rate of the coolant in the coolant flow path  14   a , the flow rate of the coolant detected by the flow rate sensor may be acquired. Further, the coolant circulation section  14  may include an electric pump instead of the mechanical pump. 
     Further, in the above-mentioned embodiment, while the magnet temperature estimation device  10  for a rotating electric machine includes the coil temperature sensor  48 , it is not limited thereto and the coil temperature sensor  48  may be omitted. The control device  17  may estimate a temperature of the coil  21  (a coil temperature) of the driving motor  11  by, for example, an appropriate calculation or the like. 
     Further, in the above-mentioned embodiment, while the magnet temperature estimation device  10  for a rotating electric machine includes the torque sensor  46 , it is not limited thereto and the torque sensor  46  may be omitted. The control device  17  may acquire a torque indicator value according to an alternating current flowing through the coils  21  of the driving motor  11  detected by the second current sensor  43  and a rotation angle of the driving motor  11  detected by the first number-of-revolutions sensor  44 . 
     Further, in the above-mentioned embodiment, while each of the driving motor  11  and the generating motor  12  includes the coil  21  of segment conductor (SC) winding, it is not limited thereto. Each of the driving motor  11  and the generating motor  12  may be a motor having another winding structure such as concentrated winding, distributed winding or the like. 
     The above-mentioned embodiment is exemplarily provided, and is not intended to limit the scope of the present invention. The above-mentioned novel embodiment may be performed as other various types, and various omissions, substitutions and changes may be made without departing from the scope of the present invention. The above-mentioned embodiment or modifications thereof are included in the scope of the present invention and included in the scope equivalent of the present invention disclosed in the scope of the claims. 
     REFERENCE SIGNS LIST 
     
         
         
           
               10  Magnet temperature estimation device for rotating electric machine 
               11  Driving motor (rotating electric machine) 
               12  Generating motor 
               13  Transmission 
               14  Coolant circulation section (coolant supply part) 
               14   b  Cooler (cooling part) 
               15  Power conversion part 
               16  Battery 
               17  Control device 
               21  Coil 
               22  Stator 
               23  Magnet 
               24  Rotor 
               24   a  Rotor yoke 
               24   b  End surface plate 
               51  Heating value calculation part 
               52  Dropped coolant temperature calculation part (coolant temperature calculation part) 
               53  Magnet temperature calculation part 
               54  Motor controller 
               55  Storage