JP6740114B2 - Motor system - Google Patents

Description

The present invention relates to control of a motor system using a motor in which a permanent magnet is attached to a rotor.

In recent years, motors having permanent magnets incorporated in rotors have been widely used as drive motors for electric vehicles. It is known that the permanent magnet incorporated in the rotor is demagnetized when the temperature rises to a predetermined temperature or higher, and the operating efficiency (rotation efficiency, power generation efficiency) is reduced.

Therefore, the stator temperature detected by the thermistor provided near the stator coil and the permanent magnet temperature of the rotor are estimated based on the temperature of the cooling oil of the motor, and when the estimated magnet temperature exceeds a predetermined threshold value, A method has been proposed in which the carrier frequency of the inverter is increased to reduce the ripple current and suppress the temperature rise of the permanent magnet (for example, refer to Patent Document 1).

Further, a method has also been proposed in which the output of a drive motor of an electric vehicle is limited based on the stator temperature detected by a thermistor and the temperature of cooling oil of the motor to suppress demagnetization of a permanent magnet incorporated in a rotor. (For example, refer to Patent Document 2).

JP, 2010-93982, A JP, 2014-42400, A

By the way, since the temperature of the permanent magnet incorporated in the rotor is affected by the torque and the number of revolutions of the motor, the method of estimating the magnet temperature from the temperature of the stator and the temperature of the cooling oil as described in Patent Document 1 is used. Then, the estimation accuracy of the magnet temperature becomes low. Therefore, when the output of the motor is limited based on the magnet temperature estimated by such a method, the output of the motor may be excessively limited.

Therefore, an object of the present invention is to improve the estimation accuracy of the temperature of the permanent magnet incorporated in the rotor and suppress the excessive output limitation.

The motor system of the present invention includes a motor having a rotor to which a permanent magnet is attached and a stator around which a coil is wound, a coil temperature sensor for detecting the temperature of the coil, and a temperature of a cooling liquid for cooling the motor. A motor system comprising: a coolant temperature sensor for detecting; a rotation speed sensor for detecting a rotation speed of the rotor; and a controller for adjusting an output of the motor based on an input torque command value, the controller comprising: Is the coil temperature detected by the coil temperature sensor, the temperature of the cooling liquid detected by the cooling liquid temperature sensor, the rotation speed of the rotor detected by the rotation speed sensor, and the torque command value of the motor. A magnet temperature estimation unit that calculates an estimated temperature of the permanent magnet based on a target operating point, and an output limit that limits the output of the motor based on the estimated temperature of the permanent magnet calculated by the magnet temperature estimation unit. Part, a maximum torque line of the motor, a maximum output line, and an operating region surrounded by a maximum rotational speed line, a second region in which both the rotational speed and the torque command value are large, and the torque command value is in the second region. Similarly, a first region in which the rotation speed is lower than the second region, a fourth region in which the rotation speed is similar to the second region and a torque command value is smaller than the second region, and both the rotation speed and the torque command value are And a storage unit that stores a selection chart that associates a calculation formula of an estimated magnet temperature or a map with each of the divided regions into four regions, a third region smaller than the second region, and the magnet temperature. The estimation unit includes a calculation formula selection unit and an estimated magnet temperature calculation unit, and the calculation formula selection unit selects a calculation formula or map of the estimated magnet temperature based on the target operating point of the motor and the selection chart. Then, the estimated temperature of the permanent magnet is calculated based on the selected calculation formula or map .

INDUSTRIAL APPLICABILITY The present invention can improve the estimation accuracy of the temperature of the permanent magnet incorporated in the rotor and suppress excessive output limitation.

It is a systematic diagram which shows the structure of the motor system in embodiment of this invention. It is a functional block diagram of a controller in a motor system of an embodiment of the present invention. It is explanatory drawing which shows the correlation of the temperature of a cooling fluid, the actual temperature of a permanent magnet, and the correlation of a coil temperature and the actual temperature of a permanent magnet. It is explanatory drawing which shows the correlation of a rotor rotation speed and the iron loss of a rotor, and the correlation of the output torque of a motor, and the iron loss of a rotor. 6 is a selection chart for selecting a calculation formula or a map used when an estimated magnet temperature calculation unit calculates an estimated magnet temperature based on a target operating point of a motor that is determined by a rotation speed of a rotor and a torque command value. It is explanatory drawing which shows the map 2 corresponding to the area|region 2 shown in FIG. 5, and the map 3 corresponding to the area|region 3 shown in FIG. 6 is an allowable torque map showing an allowable torque with respect to an estimated magnet temperature. It is a flow chart which shows operation of the motor system of the present invention. It is a functional block diagram of a controller in a motor system of other embodiments of the present invention. 6 is a graph showing a relationship between an actual back electromotive force voltage of a motor and a reference back electromotive force voltage in motor design. 6 is a flowchart showing an operation of calculating an allowable torque correction coefficient in a motor system according to another embodiment of the present invention. 7 is a flowchart showing a repetitive operation in a motor system according to another embodiment of the present invention.

Hereinafter, a motor system 100 according to an embodiment of the present invention will be described with reference to the drawings. In the following description, the motor system 100 is described as being mounted on the electric vehicle 200, but may be mounted on another device.

First, an electric vehicle 200 in which the motor system 100 is mounted will be described. As shown in FIG. 1, an electric vehicle 200 includes a motor 10 for driving the vehicle, a battery 30, an inverter 34 that converts the DC power of the battery 30 into AC power and supplies the AC power to the motor 10, and wheels 44 by the motor 10. It includes a drive mechanism 40 for driving the motor 10, a cooling device 20 for cooling the motor 10, and a controller 50 for adjusting the output of the motor 10.

As shown in FIG. 1, a motor 10 includes a casing 11, a stator 12 attached to the inside of the casing 11, a rotor 14 arranged on the inner periphery of the stator 12, and a rotating shaft integrally fixed to the rotor 14. 16 and. A coil 13 is wound around the stator 12. A coil temperature sensor 17 that detects the coil temperature Tc is attached to the coil 13. The rotor 14 has a cylindrical shape in which electromagnetic steel sheets are laminated, and a permanent magnet 15 is incorporated inside the outer periphery thereof. A resolver 18, which is a rotation speed sensor that detects the rotation angle θ and the rotation speed R of the rotor 14, is attached to one end of the rotation shaft 16.

The battery 30 is a chargeable/dischargeable secondary battery, and may be, for example, a nickel hydrogen battery, a lithium ion battery, or the like. The positive electrode and the negative electrode of the battery 30 are connected to the inverter 34 through the high piezoelectric path 31 and the ground electric path 32, respectively. A voltage sensor 33 that detects the voltage Vb of the battery 30 is attached between the high-voltage path 31 and the ground electric path 32.

The inverter 34 includes switching elements such as a plurality of FETs inside, and turns on/off the switching elements according to the PWM signal input from the controller 50, and outputs from the battery 30 input from the high piezoelectric path 31 and the ground electric path 32. DC power is converted into AC power and supplied to the motor 10 from the AC circuit 35. Further, the inverter 34 turns on and off the switching element by the PWM signal input from the controller 50, converts the AC regenerative power of the motor 10 input from the AC power line 35 into DC power, and converts the AC power to the high-voltage path 31 and the ground. The battery 30 is charged through the electric path 32. Here, the alternating-current electric path 35 is composed of three electric paths: a U-phase electric path 35u, a V-phase electric path 35v, and a W-phase electric path 35w. A current sensor 36 for detecting the V-phase current Iv and a current sensor 37 for detecting the W-phase current Iw are attached to the V-phase electric path 35v and the W-phase electric path 35w, respectively.

A cooling device 20 that cools the motor 10 includes an oil pan 22 that is provided below the motor 10 to store a cooling liquid 21 such as cooling oil, and an oil pump 23 that pressurizes the cooling liquid 21 stored in the oil pan 22. A cooling liquid circulation pipe 24 for circulating the pressurized cooling liquid 21 in the casing 11 of the motor 10 and a cooling liquid temperature sensor 25 for detecting the temperature To of the cooling liquid 21 stored in the oil pan 22. I'm out. As shown in FIG. 1, the cooling liquid 21 that has flowed into the inside of the casing 11 of the motor 10 through the cooling liquid circulation pipe 24 cools the coil 13 of the stator 12 and flows from the bottom of the casing 11 to the oil pan 22. Return. The cooling liquid 21 is stored in the lower portion of the casing 11, and the lower portion of the stator 12 and the lower portion of the rotor 14 are submerged in the cooling liquid 21 stored in the casing 11.

The drive mechanism 40 is connected to the rotary shaft 16 of the motor 10 to transmit the drive force of the motor 10, a differential gear 42 that transmits the rotation of the drive shaft 41 to the rotation of the axle 43, and the axle 43. Includes mounted wheels 44.

Here, the motor 10, the coil temperature sensor 17, the coolant temperature sensor 25, the resolver 18 which is a rotation speed sensor, and the controller 50 constitute a motor system 100.

As shown in FIG. 1, the controller 50 is a computer that includes a device/sensor interface 53 connected to devices and sensors, a storage unit 52 that stores control data and operation programs, and a CPU 51 that performs arithmetic processing. The CPU 51, the storage unit 52, and the device/sensor interface 53 are connected by a data bus 60. The device/sensor interface 53 is connected to the resolver 18, the voltage sensor 33, the current sensors 36 and 37, the coil temperature sensor 17, and the coolant temperature sensor 25. The rotation angle θ and the rotational speed R of the rotor 14, the voltage Vb of the battery 30, the V-phase current Iv, the W-phase current Iw, the coil temperature Tc, and the cooling detected by the resolver 18 and the sensors 33, 36, 37, 17, and 25. The temperature To of the liquid 21 is input to the controller 50 through the device/sensor interface 53. The device/sensor interface 53 is connected to the inverter 34. The controller 50 outputs the PWM signal calculated by the CPU 51 to the inverter 34 through the device/sensor interface 53. Further, the torque command value Tr ^* of the motor 10 calculated by another control device (not shown ⁾ is input to the controller 50.

The storage unit 52 stores control data for executing control of the motor 10, a program, a selection chart shown in FIG. 5, a map shown in FIG. 6, and an allowable torque map shown in FIG. 7.

Next, the functional blocks of the controller 50 will be described with reference to FIG. As shown in FIG. 2, the controller 50 includes a magnet temperature estimating unit 54 and an output limiting unit 57. Further, as shown in FIG. 2, the magnet temperature estimation unit 54 includes a calculation formula selection unit 55 and an estimated magnet temperature calculation unit 56. The output limiting unit 57 is composed of a torque command value resetting unit 58 and a PWM control unit 59.

The rotational speed R of the motor 10 and the torque command value Tr ^* of the motor 10 input from another control device (not shown) are input to the calculation formula selection unit 55. The calculation formula selection unit 55 uses the target operating point of the motor 10 determined by the input rotation speed R and the torque command value Tr ^* , the selection chart shown in FIG. 5, and the estimated magnet temperature calculation unit using the map shown in FIG. 56 selects a calculation formula or map used when calculating the estimated magnet temperature Tm of the permanent magnet 15.

The estimated magnet temperature calculation unit 56 includes a calculation formula or map selected by the calculation formula selection unit 55, a coil temperature Tc detected by the coil temperature sensor 17, and a temperature To of the cooling liquid 21 detected by the cooling liquid temperature sensor 25. And are entered. The estimated magnet temperature calculation unit 56 calculates the estimated magnet temperature Tm using the input calculation formula or map, the coil temperature Tc, and the temperature To of the cooling liquid 21, and outputs the calculated estimated magnet temperature Tm.

As described above, the magnet temperature estimation unit 54 including the calculation formula selection unit 55 and the estimated magnet temperature calculation unit 56 causes the coil temperature Tc detected by the coil temperature sensor 17 and the cooling detected by the coolant temperature sensor 25. The estimated magnet temperature Tm of the permanent magnet 15 is calculated based on the temperature To of the liquid 21 and the target operating point of the motor 10 which is determined by the rotational speed R of the rotor 14 detected by the resolver 18 and the torque command value Tr ^* .

In the torque command value resetting unit 58, the estimated magnet temperature Tm output by the estimated magnet temperature calculation unit 56, the rotation speed R of the rotor 14 detected by the resolver 18, and the torque command value input from another control device are input. Tr ^* and are input. The torque command value resetting unit 58 calculates the allowable torque Tra of the motor 10 based on the input rotational speed R and the estimated magnet temperature Tm with reference to the allowable torque map shown in FIG. 7, and calculates the calculated allowable torque. is reset and outputs the allowable torque Tra as a torque command value Tr2 ^* when comparing the Tra and the torque command value Tr ^* and the torque command value Tr ^* exceeds the permissible torque Tra. Further, when the torque command value Tr ^* of lower than the allowable torque Tra and outputs the re-sets the torque command value Tr ^* as the torque command value Tr2 ^*. In this way, the torque command value resetting unit 58 limits the torque command value Tr2 ^* to the allowable torque Tra or less based on the estimated magnet temperature Tm.

In the PWM control unit 59, the torque command value Tr2 ^* reset by the torque command value resetting unit 58, the voltage Vb of the battery 30 detected by the voltage sensor 33, and the V-phase current Iv detected by the current sensors 36, 37. The W-phase current Iw and the rotation angle θ of the rotor 14 detected by the resolver 18 are input. The PWM control unit 59 outputs a PWM signal for turning on/off the switching element of the inverter 34 based on the input torque command value Tr2 ^* , voltage Vb, V-phase current Iv, W-phase current Iw, and rotation angle θ. Output. In this way, the PWM control unit 59 adjusts the output of the motor 10 based on the limited torque command value Tr2 ^* .

As described above, the output limiting unit 57 including the torque command value resetting unit 58 and the PWM control unit 59 uses the torque command value based on the estimated magnet temperature Tm of the permanent magnet 15 calculated by the magnet temperature estimating unit 54. The output of the motor 10 is limited by limiting Tr2 ^* to the allowable torque Tra or less.

The functional block of the controller 50 illustrated in FIG. 2 described above is realized by software including a CPU 51 and a storage unit 52 included in the controller 50, and a program read from the storage unit 52 and executed by the CPU 51. ..

Next, the selection chart (FIG. 5) and the map (FIG. 6) stored in the storage unit 52 will be described with reference to FIGS. 3 to 6. The selection chart shown in FIG. 5 is a chart to be referred to when the estimated magnet temperature calculation unit 56 selects a calculation formula or a map used when calculating the estimated magnet temperature Tm of the permanent magnet 15.

First, a basic calculation formula of the estimated magnet temperature Tm of the permanent magnet 15 will be described with reference to FIG. As shown in FIG. 3 to FIG. 6, the unit of the actual temperature Tma of the permanent magnet 15, the estimated magnet temperature Tm, the temperature To of the cooling liquid 21, the coil temperature Tc is (° C.), and the unit of the iron loss Lf is (W /Kg), the unit of the rotational speed R of the rotor 14 is (rpm), the unit of the output torque Tr of the motor 10 and the torque command value Tr ^* is (N*m).

FIG. 3A is a graph showing the correlation between the temperature To of the coolant 21 detected by the coolant temperature sensor 25 of the motor 10 and the actual temperature Tma of the permanent magnet 15 incorporated in the rotor 14. As described above, the cooling liquid 21 is stored in the lower portion of the casing 11 of the motor 10, and the lower portion of the rotor 14 is submerged in the cooling liquid 21. Therefore, as indicated by the solid line 71 in FIG. 3A, the actual temperature Tma of the permanent magnet 15 incorporated in the rotor 14 is substantially proportional to the temperature To of the cooling liquid 21, and the temperature To of the cooling liquid 21 increases. Rise according to.

FIG. 3B is a graph showing the correlation between the coil temperature Tc detected by the coil temperature sensor 17 and the actual temperature Tma of the permanent magnet 15 incorporated in the rotor 14. Both the temperature Tc of the coil 13 and the actual temperature Tma of the permanent magnet 15 have characteristics that they become higher as the output of the motor 10 becomes larger. Therefore, as indicated by the solid line 72 in FIG. 3B, the actual temperature Tma of the permanent magnet 15 increases in proportion to the increase in the coil temperature Tc.

From the correlation between the actual temperature Tma of the permanent magnet 15, the temperature To of the cooling liquid 21 and the coil temperature Tc as described above, the estimated magnet temperature Tm of the permanent magnet 15 is calculated based on the temperature To of the cooling liquid 21 and the coil temperature Tc. The following calculation formula to be estimated is derived.

Estimated magnet temperature Tm (°C) = A x To + B x Tc + C
Here, A, B, and C are constants.

Next, the correlation between the iron loss Lf of the rotor 14 and the rotational speed R of the rotor 14 and the correlation between the iron loss Lf of the rotor 14 and the output torque Tr of the motor 10 will be described with reference to FIG. As shown by the solid line 73 in FIG. 4A, the iron loss Lf of the rotor 14 increases substantially in proportion to the rotation speed R of the rotor 14. Further, as shown by the solid line 74 in FIG. 4B, the iron loss Lf of the rotor 14 increases as the output torque Tr of the motor 10 increases, and the increase rate of the iron loss Lf increases as the output torque Tr of the motor increases. Getting smaller.

The iron loss Lf of the rotor 14 and the actual temperature Tma of the permanent magnet 15 are in a substantially proportional relationship. Therefore, the larger the rotational speed R and the output torque Tr of the motor 10, the higher the actual temperature Tma of the permanent magnet 15 of the rotor 14, and the smaller the rotational speed R and the output torque Tr of the motor 10, the actual temperature of the permanent magnet 15. Tma will be lower. Further, as shown in FIGS. 4(a) and 4(b), the rotational speed R has a larger influence on the iron loss Lf, so that the motor output torque is larger when the rotational speed R of the rotor 14 is larger. The temperature of the permanent magnet 15 tends to be higher than that when Tr is large.

Therefore, in the motor system 100 of the present embodiment, as shown in FIG. 5, the operating region of the motor 10 surrounded by the maximum torque line 75, the maximum equal output line 76, and the maximum rotation speed line 77 is from region 1 to region 1. The storage unit 52 stores a selection chart in which the area is divided into four areas 4 and a calculation formula or map used for calculating the estimated magnet temperature Tm is associated with each area.

Region 2 in the selection chart shown in FIG. 5 is surrounded by a rotation speed division line 78, a torque command value division line 79, a maximum torque line 75, and a maximum equal output line 76, and the rotation speed R of the rotor 14 is greater than α. This is a region where the torque command value Tr ^* is large and is larger than β. Region 2 is a region where the actual temperature Tma of the permanent magnet 15 is estimated to be higher than other regions.

Region 3 in the selection chart shown in FIG. 5 is surrounded by a rotation speed division line 78 and a torque command value division line 79, the rotation speed R of the rotor 14 is smaller than α, and the torque command value Tr ^* is β. Is a smaller area. The region 3 is a region where the actual temperature Tma of the permanent magnet 15 is estimated to be lower than the other regions.

Region 1 in the selection chart shown in FIG. 5 is surrounded by the maximum torque line 75, the rotation speed division line 78, and the torque command value division line 79, the rotation speed R of the rotor 14 is smaller than α, and the torque command This is a region where the value Tr ^* is larger than β. Region 4 in the selection chart shown in FIG. 5 is surrounded by the maximum rotation speed line 77, the rotation speed division line 78, and the torque command value division line 79, and the rotation speed R of the rotor 14 is larger than α, and , Where the torque command value Tr ^* is smaller than β. Regions 1 and 4 are regions where the actual temperature Tma of the permanent magnet 15 is estimated to be intermediate between the regions 2 and 3. As shown in FIGS. 4(a) and 4(b), the rotational speed R of the rotor 14 has a greater effect on the iron loss Lf than the torque command value Tr ^* , so that the actual temperature Tma of the permanent magnet 15 is increased. A large impact. Therefore, between the actual temperature Tma of the permanent magnet 15 in the area 4 and the actual temperature Tma of the permanent magnet 15 in the area 1 in the selection chart shown in FIG. 5, the actual temperature Tma of the permanent magnet 15 in the area 4 is the area 1 It is estimated that the temperature becomes higher than the actual temperature Tma of the permanent magnet 15 of.

In the motor system 100 of the present embodiment, the following formula is used to calculate the estimated magnet temperature Tm of the permanent magnet 15 from the temperature To of the coolant 21 and the coil temperature Tc in the regions 1 to 4 in the selection chart shown in FIG. It is defined as (Expression 1) to (Expression 4) shown in FIG.

Area 1: Estimated magnet temperature Tm=A1×To+B1×Tc+C1 (Equation 1)
Region 2: Estimated magnet temperature Tm=A2×To+B2×Tc+C2 (Equation 2)
Region 3: Estimated magnet temperature Tm=A3×To+B3×Tc+C3 (Equation 3)
Region 4: Estimated magnet temperature Tm=A4×To+B4×Tc+C4 (Equation 4)

In (Equation 1) to (Equation 4), A1 to A4, B1 to B4, and C1 to C4 are constants.

Then, the estimated magnet temperatures Tm of the areas 1 to 4 in the selection chart shown in FIG. 5 calculated by the equations 1 to 4 are such that the estimated magnet temperature Tm of the area 2>the estimated magnet temperature Tm of the area 4 The constants A1 to A4, B1 to B4, and C1 to C4 are set as follows, for example, such that >estimated magnet temperature Tm in area 1>estimated magnet temperature Tm in area 3 is satisfied.

A2>A4>A1>A3
B2>B4>B1>B3
C2>C4>C1>C3

Each estimated magnet temperature Tm of the regions 1 to 4 in the selection chart shown in FIG. 5 is such that the estimated magnet temperature Tm of the region 2>the estimated magnet temperature Tm of the region 4>the estimated magnet temperature Tm of the region 1>the region 3 If the estimated magnet temperature Tm is reached, the constants A1 to A4, B1 to B4, and C1 to C4 are not limited to the above, and may be set as follows, for example.

A2>A1>A4>A3
B2>B1>B4>B3
C2>C1>C4>C3

Further, in the motor system 100 according to the present embodiment, the map 4 is stored in the map 1 used in calculating the estimated magnet temperature Tm of the permanent magnets 15 in the areas 1 to 4 in the selection chart shown in FIG. Stored in. A map 2 for calculating the estimated magnet temperature Tm of the permanent magnet 15 in the area 2 and a map 3 for calculating the estimated magnet temperature Tm of the permanent magnet 15 in the area 3 will be described with reference to FIG. 6.

As shown in FIG. 6A, in the map 2, the temperature of the cooling liquid 21 when the coil temperature Tc is a predetermined value is obtained by sequentially substituting a plurality of predetermined values into the coil temperature Tc of (Equation 2) described above. The relationship between the estimated magnet temperature Tm and To is set as a map of a set of a plurality of solid lines 81 to 83. As shown by solid lines 81 to 83 in FIG. 6A, the estimated magnet temperature Tm increases as the temperature To of the cooling liquid 21 and the coil temperature Tc increase.

Similar to the map 2 shown in FIG. 6A, the map 3 shown in FIG. 6B also sequentially substitutes a plurality of predetermined values into the coil temperature Tc of (Equation 3) described above, and the coil temperature Tc becomes the predetermined value. In the case of, the relationship between the temperature To of the cooling liquid 21 and the estimated magnet temperature Tm is mapped as a set of a plurality of alternate long and short dash lines 84 to 86.

As described above, the constants A1 to A4, B1 to B4, and C1 to C4 are calculated as follows: the estimated magnet temperature Tm in the region 2>the estimated magnet temperature Tm in the region 4>the estimated magnet temperature Tm in the region 1>the estimated magnet in the region 3 For example, A2>A4>A1>A3, B2>B4>B1>B3, C2>C4>C1>C3 are set so as to reach the temperature Tm. Therefore, when the temperature To of the coolant 21 is the same To1 and the coil temperature Tc is the same Tc1, the estimated magnet temperature Tm is Tm2 in Map 2, whereas the estimated magnet temperature Tm is Tm2 in Map 3. It is lower than Tm3. Map 1 corresponding to area 1 and map 4 corresponding to area 4 have the same configurations as map 2 and map 3. Then, when the temperature To of the cooling liquid 21 and the coil temperature Tc are the same, the estimated magnet temperature Tm estimated using the map 1 and the map 4 is calculated using the estimated magnet temperature Tm estimated using the map 2 and the map 3. The value is an intermediate value of the estimated estimated magnet temperature Tm, and the estimated magnet temperature Tm estimated using the map 4 is higher than the estimated magnet temperature Tm estimated using the map 1.

Next, an allowable torque map showing the allowable torque Tra with respect to the estimated magnet temperature Tm shown in FIG. 7 will be described. The allowable torque map shown in FIG. 7 is stored in the storage unit 52. A solid line 91 in FIG. 7 shows a change in the allowable torque Tra with respect to the rotation speed R when the estimated magnet temperature Tm is low and there is no torque limitation with respect to the rotation speed R of the rotor 14. As the estimated magnet temperature Tm becomes higher, the rotation speed R at which the maximum torque Tr0 can be output decreases as shown by the solid lines 92 and 93. As a result, the torque is limited and the output of the motor 10 is limited in the high rotation range. When the estimated magnet temperature Tm further rises, the maximum torque that can be output is reduced from Tr0 to Tr1, Tr2, Tr3, as shown by the solid lines 94 to 96. As a result, the torque and output of the motor 10 are limited over the entire rotation speed R of the rotor 14.

Next, the operation of the controller 50 will be described with reference to FIG. The controller 50 repeatedly executes steps S101 to S113 shown in FIG. 8 for each predetermined cycle Δt (for example, 0.1 seconds). Steps S101 to S103 shown in FIG. 8 are executed by the calculation formula selection unit 55, and steps S104 and S105 shown in FIG. 8 are executed by the estimated magnet temperature calculation unit 56. Further, steps S106 to S108 and S111 shown in FIG. 8 are executed by the torque command value resetting unit 58, and steps S109, S110, S112 and S113 shown in FIG. 8 are executed by the PWM control unit 59. Further, another control device (not shown) calculates and outputs the torque command value Tr ^* of the motor 10 based on, for example, the vehicle speed of the electric vehicle 200, the position of the shift lever, the accelerator opening or the brake opening, and the like. ..

As shown in step S101 of FIG. 8, the calculation formula selection unit 55 acquires the torque command value Tr ^* of the motor 10 from another control device (not shown). Next, the calculation formula selection unit 55 detects the rotation speed R of the rotor 14 from the resolver 18, as shown in step S102 of FIG. After obtaining the torque command value Tr ^* and the rotational speed R of the rotor 14, the calculation formula selection unit 55 stores the acquired torque command value Tr ^* and rotational speed R in the storage unit 52, and proceeds to step S103 of FIG. move on. The calculation formula selection unit 55 confirms the target operating point of the motor 10 determined from the torque command value Tr ^* and the rotation speed R of the rotor 14 in step S103 of FIG. Then, the calculation formula selection unit 55 refers to the selection chart shown in FIG. 5 stored in the storage unit 52, and the target operating point of the motor 10 is changed from the region 1 to the region 4 of the selection chart shown in FIG. Check if there is. Then, for example, when the target operating point of the motor 10 is in the region 1, the calculation formula selection unit 55 selects (Formula 1) or (Map 1). In this way, the calculation formula selection unit 55 selects (Formula N) or (Map N) when the target operating point of the motor 10 is in the region N (N is an integer from 1 to 4).

The estimated magnet temperature calculation unit 56 acquires the coil temperature Tc and the temperature To of the cooling liquid 21 from the coil temperature sensor 17 and the cooling liquid temperature sensor 25 in step S104 of FIG. The estimated magnet temperature calculation unit 56 stores the acquired coil temperature Tc and the acquired temperature To of the cooling liquid 21 in the storage unit 52, and proceeds to step S105 in FIG. In step S105 of FIG. 8, the estimated magnet temperature calculation unit 56 calculates the estimated magnet temperature Tm using the calculation formula or map selected by the calculation formula selection unit 55, the coil temperature Tc, and the temperature To of the cooling liquid 21. , Estimated magnet temperature Tm is output.

The torque command value resetting unit 58, in step S106 shown in FIG. 8, the allowable torque map shown in FIG. 7 stored in the storage unit 52, the estimated magnet temperature Tm output by the estimated magnet temperature calculation unit 56, and the storage unit. The allowable torque Tra of the motor 10 is calculated based on the rotational speed R of the rotor 14 read from 52. After calculating the allowable torque Tra of the motor 10, the torque command value resetting unit 58 proceeds to step S107 of FIG. 8 and determines the allowable torque Tra calculated by the torque command value Tr ^* of the motor 10 input from another control device. Determine if it exceeds. If the torque command value Tr ^* exceeds the calculated allowable torque Tra, the process proceeds to step S108 in FIG. 8 and the allowable torque Tra is reset to the torque command value Tr2 ^* output to the PWM control unit 59.

In step S109 of FIG. 8, the PWM control unit 59 sets the voltage Vb of the battery 30, the V-phase current Iv, the W-phase current Iw, and the rotation angle θ of the rotor 14 from the voltage sensor 33, the current sensors 36 and 37, and the resolver 18, respectively. get. The PWM control unit 59 stores the acquired voltage Vb, V-phase current Iv, W-phase current Iw, and rotation angle θ of the rotor 14 in the storage unit 52, and proceeds to step S110 in FIG. In step S110 of FIG. 8, the PWM control unit 59 sets the torque command value Tr2 ^* reset to the allowable torque Tra by the torque command value resetting unit 58, the voltage Vb of the battery 30, the V-phase current Iv, and the W-phase. Based on the current Iw and the rotation angle θ of the rotor 14, a PWM signal for turning on/off the switching element of the inverter 34 is output. This PWM signal is a signal for driving the motor 10 by limiting the output torque of the motor 10 to the allowable torque Tra or less. In this way, the output of the motor 10 is limited by the estimated magnet temperature Tm of the permanent magnet 15.

On the other hand, if the torque command value resetting unit 58 determines that the torque command value Tr ^* is equal to or less than the calculated allowable torque Tra and it is NO in step S107 of FIG. 8, the process proceeds to step S111 of FIG. The torque command value Tr2 ^* output to the unit 59 is reset to the torque command value Tr ^* acquired from another control device. Then, in step S112 of FIG. 8, as in step S109, the PWM control unit 59 receives the voltage Vb of the battery 30, the V-phase current Iv, and the W-phase current Iw from the voltage sensor 33, the current sensors 36 and 37, and the resolver 18, respectively. , The rotation angle θ of the rotor 14 is acquired, and the process proceeds to step S113 in FIG. PWM control unit 59, in step S113 of FIG. 8, the torque command value Tr2 ^* which is reset to the torque command value Tr ^* in the torque command value resetting unit 58, and the voltage Vb of the battery 30, V-phase current Iv, Based on the W-phase current Iw and the rotation angle θ of the rotor 14, a PWM signal for turning on/off the switching element of the inverter 34 is output. This PWM signal is a signal for driving the motor 10 without limiting the output torque of the motor 10 from the torque command value Tr ^* . Therefore, in this case, the output of the motor 10 is not limited by the estimated magnet temperature Tm of the permanent magnet 15.

As described above, the motor system 100 of the present embodiment uses the selection chart shown in FIG. 5 to select the permanent magnet 15 from the selection chart shown in FIG. 5 based on the target operating point of the motor 10 determined by the rotation speed R of the rotor 14 and the torque command value Tr ^* . The estimated magnet temperature Tm of the permanent magnet 15 is calculated with accuracy because the estimated magnet temperature Tm of the permanent magnet 15 is calculated using the selected equation or map that can accurately calculate the estimated magnet temperature Tm. It can be well estimated. Then, since the output of the motor 10 is limited by using the estimated magnet temperature Tm calculated with high accuracy, it is possible to suppress the output of the motor 10 from being excessively limited. When the motor system 100 according to the present embodiment is mounted on the electric vehicle 200, the estimated magnet temperature Tm of the permanent magnet 15 of the motor 10 for driving the vehicle is accurately estimated to suppress an excessive output limitation of the motor 10 and the vehicle. It is possible to prevent the performance from decreasing.

Next, another embodiment of the motor system 100 of the present embodiment will be described with reference to FIGS. 9 to 11. The same parts as those of the embodiment described above with reference to FIGS. 1 to 8 are designated by the same reference numerals and the description thereof will be omitted.

FIG. 9 is a functional block diagram of the controller 50 of the motor system 100 according to another embodiment. The controller 50 of the motor system 100 of the present embodiment is obtained by adding a torque correction coefficient calculation unit 61 to the controller 50 of the embodiment described above with reference to FIG. Further, the controller 50 of the present embodiment stores the time change curve of the reference back electromotive force in motor design, which is indicated by the solid line 99 in FIG.

The torque correction coefficient calculation unit 61 detects the counter electromotive voltage of the motor 10 and calculates the allowable torque correction coefficient K from the ratio of the detected maximum value of the counter electromotive voltage to the maximum value of the reference counter electromotive voltage in motor design. Is.

Similar to the embodiment described above, the functional blocks of the controller 50 shown in FIG. 9 mainly include a CPU 51 and a storage unit 52 included in the controller 50, and a program read from the storage unit 52 and executed by the CPU 51. It is realized by software.

The operation of the controller 50 of this embodiment will be described below with reference to FIGS. 11 and 12. After executing steps S201 and S202 shown in FIG. 11, the controller 50 repeats steps S101 to S105, S203, and S107 to S113 shown in FIG. 11 at every predetermined cycle Δt (for example, 0.1 seconds). Execute.

Steps S201 and S202 shown in FIG. 11 are executed by the torque correction coefficient calculation unit 61. Steps S101 to S103 shown in FIG. 12 are executed by the calculation formula selection unit 55, and steps S104 and S105 shown in FIG. 12 are executed by the estimated magnet temperature calculation unit 56. Further, steps S106, S203, S204, S205 and S111 shown in FIG. 12 are executed by the torque command value resetting unit 58, and steps S109, S110, S112 and S113 shown in FIG. 12 are executed by the PWM control unit 59. Further, another control device (not shown) calculates and outputs the torque command value Tr ^* of the motor 10 based on the vehicle speed of the electric vehicle 200, the position of the shift lever, the accelerator opening degree, the brake opening degree, and the like. .. In the following description, the same steps as those described with reference to FIG. 8 are designated by the same reference numerals and the description thereof will be omitted.

As shown in step S201 of FIG. 11, the torque correction coefficient calculation unit 61 detects the counter electromotive voltage waveform of the motor 10 and stores it in the storage unit 52. The detection of the back electromotive force waveform of the motor 10 is performed by, for example, opening all the switching elements of the inverter 34 and attaching the motor 10 to the AC circuit 35 shown in FIG. Alternatively, the voltage may be detected by detecting the AC voltage of the AC circuit 35 with a voltage sensor (not shown). Such a state can be realized by, for example, opening all the switching elements of the inverter 34 and allowing the electric vehicle 200 to coast. The torque correction coefficient calculation unit 61 detects the back electromotive voltage waveform of the motor 10 as a time-varying AC voltage waveform as indicated by a broken line 98 in FIG. 10. As indicated by a broken line 98 in FIG. 10, the maximum value of the back electromotive voltage waveform of the motor 10 is V1. After detecting the counter electromotive voltage waveform of the motor 10, the torque correction coefficient calculation unit 61 proceeds to step S202 in FIG.

In step S202 of FIG. 11, the torque correction coefficient calculation unit 61 reads from the storage unit 52 the reference back electromotive force waveform in motor design shown by the solid line 99 in FIG. As shown by the solid line 99 in FIG. 10, the maximum value of this reference counter electromotive voltage waveform is V2. Then, the torque correction coefficient calculation unit 61 calculates the allowable torque correction coefficient K as described below and stores it in the storage unit 52.

Allowable torque correction coefficient K = V1/V2

The motor 10 is designed so that the back electromotive force is higher than the reference back electromotive force. Therefore, since the actual back electromotive force of each motor 10 is larger than this reference back electromotive force, the allowable torque correction coefficient K=V1/V2 becomes a value larger than 1. In the case of the motor 10 in which the back electromotive force is larger than the designed reference back electromotive voltage, it is possible to output a torque larger than the designed torque when the designed voltage and current are applied. Therefore, the motor system 100 of the present embodiment further suppresses the output limitation of the motor 10 by expanding the allowable torque Tra of the motor to the torque obtained by multiplying the value of the allowable torque Tra by the allowable torque correction coefficient K. Is.

After the execution of steps S201 and S202 shown in FIG. 10, the calculation formula selection unit 55 and the estimated magnet temperature calculation unit 56 execute steps S101 to S105 of FIG. 12 as described above with reference to FIG. The estimated magnet temperature Tm is calculated.

In step S203 shown in FIG. 12, torque command value resetting section 58 has the allowable torque map shown in FIG. 7 stored in storage section 52 and the estimated magnet temperature calculating section, similar to step S106 in FIG. 8 described above. The allowable torque Tra of the motor 10 is calculated based on the estimated magnet temperature Tm output by 56 and the rotation speed R of the rotor 14 read from the storage unit 52. Next, the torque command value resetting unit 58 multiplies the calculated allowable torque Tra by the allowable torque correction coefficient K to calculate the enlarged allowable torque K*Tra. After calculating the expansion allowable torque K*Tra of the motor 10, the torque command value resetting unit 58 proceeds to step S204 of FIG. 12 and expands the torque command value Tr ^* of the motor 10 input from another control device. It is determined whether the allowable torque K*Tra is exceeded. When the torque command value Tr ^* exceeds the expansion allowable torque K*Tra, the process proceeds to step S205 of FIG. 12, and the expansion allowable torque K*Tra is re-set to the torque command value Tr2 ^* output to the PWM control unit 59. Set.

As described with reference to FIG. 8, in step S109 of FIG. 12, the PWM control unit 59 causes the voltage sensor 33, the current sensors 36 and 37, and the resolver 18 to output the voltage Vb of the battery 30 and the V-phase currents Iv and W, respectively. The phase current Iw and the rotation angle θ of the rotor 14 are acquired, the torque command value Tr2 ^* reset to the expansion allowable torque K*Tra by the torque command value resetting unit 58, the voltage Vb of the battery 30, and the V-phase current. A PWM signal for turning on/off the switching element of the inverter 34 is output based on the Iv, the W-phase current Iw, and the rotation angle θ of the rotor 14. The PWM signal is a signal for driving the motor 10 by limiting the output torque of the motor 10 to the expansion allowable torque K*Tra or less. In this way, the output of the motor 10 is limited by the estimated magnet temperature Tm of the permanent magnet 15.

On the other hand, when the torque command value Tr ^* is equal to or less than the expansion allowable torque K*Tra and the determination is NO in step S204 of FIG. 12, the torque command value resetting unit 58 proceeds to step S111 of FIG. As described with reference to FIG. 8, the torque command value Tr2 ^* output to the PWM control unit 59 is reset to the torque command value Tr ^* obtained from another control device. The PWM control unit 59 outputs a PWM signal for driving the motor 10 without limiting the output torque of the motor 10 from the torque command value Tr ^* . Therefore, in this case, the output of the motor 10 is not limited by the estimated magnet temperature Tm of the permanent magnet 15.

As described above, the motor system 100 of the present embodiment has the same effect as that of the embodiment previously described with reference to FIGS. 1 to 8 and the enlargement allowance enlarged based on the characteristics of each motor 10. Since the output torque of the motor 10 is not limited to the torque K*Tra, it is possible to more appropriately suppress the excessive output restriction of the motor 10 and suppress the deterioration of the vehicle performance.

10 motor, 11 casing, 12 stator, 13 coil, 14 rotor, 15 permanent magnet, 16 rotating shaft, 17 coil temperature sensor, 18 resolver, 20 cooling device, 21 cooling liquid, 22 oil pan, 23 oil pump, 24 cooling liquid Circulation pipe, 25 Coolant temperature sensor, 30 Battery, 31 High-voltage line, 32 Ground line, 33 Voltage sensor, 34 Inverter, 35 AC line, 35u U-phase line, 35v V-phase line, 35w W-phase line, 36, 37 Current Sensor, 40 drive mechanism, 41 drive shaft, 42 differential gear, 43 axle, 44 wheels, 50 controller, 51 CPU, 52 storage unit, 53 sensor interface, 54 magnet temperature estimation unit, 55 calculation formula selection unit, 56 estimated magnet temperature Calculation unit, 57 output limit unit, 58 torque command value resetting unit, 59 PWM control unit, 60 data bus, 61 torque correction coefficient calculation unit, 75 maximum torque line, 76 maximum equal output line, 77 maximum rotation speed line, 78 Revolution speed division line, 79 torque command value division line, 100 motor system, 200 electric vehicle, A1 to A4, B1 to C4, C1 to C4 constant, Iv V phase current, Iw W phase current, K allowable torque correction coefficient, Lf Iron loss, R rotation speed, Tc coil temperature, Tm estimated magnet temperature, Tma actual temperature, To coolant temperature, Tr output torque, Tr ^* , Tr2 ^* torque command value, Tra allowable torque, K*Tr expansion allowable torque, Vb Voltage, Δt period, θ rotation angle.

Claims (1)

A motor having a rotor having a permanent magnet attached thereto and a stator having a coil wound around it;
A coil temperature sensor for detecting the temperature of the coil,
A cooling liquid temperature sensor for detecting the temperature of the cooling liquid for cooling the motor,
A rotation speed sensor for detecting the rotation speed of the rotor,
A motor system comprising a controller that adjusts the output of the motor based on an input torque command value,
The controller is
A target operating point of the motor determined by the coil temperature detected by the coil temperature sensor, the temperature of the cooling liquid detected by the cooling liquid temperature sensor, and the rotation speed and torque command value of the rotor detected by the rotation speed sensor. And a magnet temperature estimation unit that calculates the estimated temperature of the permanent magnet based on
An output limiting unit that limits the output of the motor based on the estimated temperature of the permanent magnet calculated by the magnet temperature estimating unit,
The operating region surrounded by the maximum torque line, the maximum output line, and the maximum rotation speed line of the motor rotates in a second region in which both the rotation speed and the torque command value are large, and the torque command value is the same as in the second region. The first region has a lower number than the second region, the fourth region has a rotational speed similar to that of the second region and the torque command value is smaller than the second region, and the rotational speed and the torque command value are both second. A storage unit that stores a selection chart that is divided into four regions, a third region smaller than the region, and a calculation formula or map of the estimated magnet temperature associated with each of the divided regions;
The magnet temperature estimation unit includes a calculation formula selection unit and an estimated magnet temperature calculation unit,
The calculation formula selection unit selects a calculation formula or map of the estimated magnet temperature based on the target operating point of the motor and the selection chart,
Calculating the estimated temperature of the permanent magnet based on a selected formula or map,
Motor system characterized by .