Motor control method and motor control device

Abstract

A motor control method and a motor control device acquire a gradient parameter indicating a road gradient of an electric vehicle, acquire a temperature parameter indicating a temperature in a motor control system including a motor, and control the motor when at least one of the gradient parameter and the temperature parameter is equal to or greater than a predetermined threshold value. A torque limiting process is executed in which the upper limit of the request torque is set to a correction torque upper limit that is less than a predetermined basic torque upper limit. Furthermore, in the torque limiting process, a first torque is determined on the basis of the gradient parameter, a second torque for applying a predetermined acceleration to the electric vehicle is determined, and a corrected torque upper limit is determined by correcting the basic torque upper limit with reference to the first torque and the second torque.

Description

Technical Field

[0001] The present invention relates to a motor control method and a motor control device having a motor as a driving source. Background Art

[0002] JP4946100B describes a motor control method having a first torque limiting unit and a second torque limiting unit. The first torque limiting unit limits the torque according to the motor temperature when the motor temperature is above a first specified value in order to avoid motor failure. The second torque limiting unit limits the torque to a constant upper limit torque that is slower than the first torque limiting unit when the motor temperature exceeds a second specified value that is smaller than the first specified value in order to suppress the motor temperature from reaching the first specified value under high load conditions such as when the electric vehicle is traveling on a long uphill road.

[0003] Problems to be solved by the invention

[0004] In the control method described in JP4946100B, when the vehicle is traveling on an uphill road with a slope of a certain degree or more, the electric motor has sufficient maximum torque performance. Although the temperature of the electric motor is within the allowable range, the upper limit of the electric motor torque is limited due to the operation of the second torque limiting unit (a limit for suppressing temperature rise), so that the desired driving performance when traveling uphill is sometimes not achieved. Summary of the invention

[0005] Therefore, the present invention aims to achieve both suppression of an excessive temperature rise in a motor control system and ensuring the running performance of the vehicle during uphill driving.

[0006] According to one embodiment of the present invention, a motor control method is provided, which controls the operation of the motor based on a specified request torque in an electric vehicle having an electric motor as a driving source. In the motor control method, a slope parameter indicating (prompting) the road slope of the electric vehicle is obtained, and a temperature parameter indicating the temperature in the motor control system including the electric motor is obtained. When at least one of the slope parameter and the temperature parameter is above a respectively specified threshold value, a torque limiting process is performed to set the upper limit of the requested torque to a corrected torque upper limit that is less than a specified basic torque upper limit. Moreover, in the torque limiting process, a first torque is determined based on the slope parameter, a second torque for giving a specified acceleration to the electric vehicle is determined, and the corrected torque upper limit is determined by correcting the basic torque upper limit with reference to the first torque and the second torque. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 It is a block diagram showing a main structure of the vehicle drive system according to the first embodiment.

[0008] Figure 2 This is a block diagram for explaining the configuration of the motor controller according to the first embodiment.

[0009] Figure 3 This is a diagram for explaining an example of a basic torque limiter.

[0010] Figure 4 This is a block diagram for explaining the structure of the gradient torque estimating unit.

[0011] Figure 5 It is an explanatory diagram showing a dynamic model of an electric vehicle.

[0012] Figure 6 : is a flowchart showing the processing of the upper-limit torque limit request determination unit.

[0013] Figure 7 This is a block diagram for explaining the configuration of the torque limiter.

[0014] Figure 8 1 is a flowchart showing the overall process of the motor control method according to the first embodiment.

[0015] Fig. 9 It is a block diagram showing a main structure of a vehicle drive system according to a second embodiment.

[0016] Fig.10 This is a block diagram illustrating the structure of a motor controller.

[0017] Fig.11 This is a diagram for explaining a method of estimating the gradient torque.

[0018] Fig.12 This is a block diagram for explaining the structure of the gradient torque estimating unit.

[0019] Fig.13 This is a diagram showing an example of a map for determining acceleration torque.

[0020] Fig.14 This is a block diagram for explaining the configuration of the torque limiter.

[0021] Fig.15 1 is a flowchart showing the overall process of the motor control method according to the second embodiment.

[0022] Fig.16 It is a graph which shows the control result of each of a comparative example and an Example. DETAILED DESCRIPTION

[0023] Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[0024] [First embodiment]

[0025] Figure 1 It is a block diagram showing the main structure of a vehicle drive system 100 mounted on an electric vehicle. As shown in the figure, the vehicle drive system 100 mainly includes a battery 1, a vehicle controller 2, a motor controller 3 as a motor control device, a PWM (Pulse Width Modulation) inverter 4, a motor 5, a reducer 6, a drive shaft 8, drive wheels 9a, 9b, a rotation sensor 20, a current sensor 21, a voltage sensor 22, and a thermistor 23. In addition, an electric vehicle refers to a vehicle that uses an electric motor as a drive source. A vehicle that can use the electric motor 5 as part or all of the drive source of the vehicle is an electric vehicle. That is, in addition to electric vehicles, electric vehicles also include hybrid vehicles or fuel cell vehicles.

[0026] The battery 1 is connected to the motor 5 via the PWM inverter 4, and supplies driving power to the motor 5 by discharging. In addition, the battery 1 is configured to be chargeable by receiving supply of regenerative power from the motor 5.

[0027] The vehicle controller 2 is composed of a computer, which is composed of, for example, a central processing unit (CPU), a read-only memory (ROM), a random access memory (RAM), and an input / output interface (I / O interface). The vehicle controller 2 generates a torque requested by the electric vehicle (hereinafter referred to as "high-level requested torque T) based on the operation of the accelerator pedal or the brake pedal by the driver of the electric vehicle and other vehicle conditions. * ”) and output to the motor controller 3.

[0028] The motor controller 3 is composed of, for example, a computer including a central processing unit (CPU), a read-only memory (ROM), a random access memory (RAM), and an input / output interface (I / O interface). The motor controller 3 is programmed to generate a torque based on the upper request torque T received from the vehicle controller 2. * , input signals from various sensors, perform the processing described below, and generate control signals (three-phase load command values ​​D u , D v , D w ).

[0029] The PWM inverter 4 includes, for example, two switching elements (for example, power semiconductor elements such as IGBT (Insulated Gate Bipolar Transistor) or MOS-FET (metal-oxide-semiconductor field-effect transistor)) corresponding to each phase. The PWM inverter 4 is based on the three-phase load command value D received from the motor controller 3. u , D v , D w The comparison result with the carrier triangular wave of the prescribed frequency generates a driving signal for the switching element. Furthermore, the PWM inverter 4 converts the DC current supplied from the battery 1 into AC current by turning the switching element on / off according to the driving signal, thereby adjusting the current supplied to the motor 5. In addition, the PWM inverter 4 reversely converts the AC current generated by the motor 5 into DC current by the regenerative braking force, thereby adjusting the current supplied to the battery 1.

[0030] The motor 5 is composed of, for example, a three-phase AC motor, and generates a driving force by the AC current supplied from the PWM inverter 4. The driving force generated by the motor 5 is transmitted to a pair of left and right drive wheels 9a and 9b via the speed reducer 6 and the drive shaft 8. In addition, when the motor 5 is rotated by the drive wheels 9a and 9b, a regenerative braking force is generated, and the kinetic energy of the vehicle drive system 100 is recovered as electric energy.

[0031] The speed reducer 6 is composed of, for example, a plurality of gears, and reduces the rotation speed of the motor 5 and transmits the reduced speed to the drive shaft 8, thereby generating a driving torque or a braking torque proportional to the reduction ratio.

[0032] The rotation sensor 20 detects the rotor position θ of the motor 5 and outputs it to the motor controller 3. The rotation sensor 20 is composed of, for example, a resolver or an encoder. The current sensor 21 detects the current flowing in the motor 5 and outputs it to the motor controller 3. In this embodiment, the current sensor 21 detects the three-phase AC current i of the motor 5, i u 、i v 、i w Alternatively, the current sensor 21 may be used to detect any two-phase currents, and the remaining one-phase current may be calculated by calculation. The voltage sensor 22 detects the DC voltage value V of the battery 1. dc The thermistor 23 detects the temperature of the stator winding of the motor 5 (hereinafter also referred to as "winding temperature T emp ”), and outputs it to the motor controller 3.

[0033] Figure 21 is a block diagram for explaining the structure of the motor controller 3. As shown in the figure, the motor controller 3 is programmed to function as a basic torque limiter 31, a rotation speed calculation unit 32, a gradient torque estimation unit 33, an upper limit torque limit request determination unit 34, a torque limit unit 35, a vibration reduction control unit 36, and a torque control unit 37.

[0034] The basic torque limiter 31 limits the upper request torque T * , the DC voltage value V from the voltage sensor 22 dc , and the speed RPM of the motor 5 are used as inputs to calculate the maximum torque T as the upper limit of the basic torque. max and basic requested torque T1.

[0035] Figure 3 The figure is used to explain the processing performed by the basic torque limiter 31. As shown in the figure, the basic torque limiter 31 firstly adjusts the speed RPM and the DC voltage value V dc , determine the maximum torque T of the motor 5, which is equivalent to the positive output limit torque max and the minimum torque T corresponding to the negative output limit torque min Moreover, the basic torque limiter 31 will be at the maximum torque T max and minimum torque T min Request torque T for the upper position * The value subjected to the limit processing is determined as the basic request torque T1. Then, the basic torque limiter 31 outputs the obtained maximum torque T to the torque limiter 35. max and basic requested torque T1.

[0036] The rotation speed calculation unit 32 receives the rotor position θ as an input, and calculates a mechanical angular velocity ω indicating the rotation speed of the motor 5 based on the temporal variation of the rotor position θ. m [rad / s], electrical angular velocity ω e [rad / s], and the rotation speed RPM [rpm]. The rotation speed calculation unit 32 calculates the mechanical angular velocity ω m The output is sent to the gradient torque estimation unit 33 and the vibration reduction control unit 36, and the electrical angular velocity ω e The rotation speed RPM is output to the torque control unit 37 , and the rotation speed RPM is output to the upper-limit torque restriction request determination unit 34 .

[0037] The gradient torque estimation unit 33 converts the mechanical angular velocity ω from the rotation speed calculation unit 32 into m and a limited requested torque T2 from the torque limiter 35, which will be described later, are used as inputs, and the gradient torque T is calculated as the first torque. s Here, the slope torque T of this embodiment sThe torque required to maintain the vehicle speed at a constant value or less (particularly 0) on an uphill road on which the electric vehicle is traveling is determined. s The torque is determined to offset the force acting on the electric vehicle in the reverse direction due to the gradient of the uphill road.

[0038] Figure 4 This is a block diagram for explaining the structure of the gradient torque estimation unit 33. As shown in the figure, the gradient torque estimation unit 33 first calculates the gradient torque by using the transfer function G as p The filter H1(s) / G is determined by the quotient of (s) relative to the filter H1(s). p (s) for mechanical angular velocity ω m Perform filtering and calculate the estimated torque T est In addition, the transfer function G p (s) represents the mechanical angular velocity ω m The output torque to the motor 5 (hereinafter also referred to as “motor torque T m ”) transfer characteristics. In addition, the filter H1(s) is configured to have a transfer function G p A low-pass filter of an order greater than or equal to the difference between the denominator and numerator of (s).

[0039] In addition, the gradient torque estimation unit 33 calculates the reference torque T by processing the limited requested torque T2 with the filter H1(s) described above. ref Then, the gradient torque estimation unit 33 uses the reference torque T ref Subtract the estimated torque T es t and calculate their deviation T err In addition, the gradient torque estimation unit 33 uses the filter H z (s) Processing deviation T err , calculate the disturbance torque T as the slope parameter d Then, the gradient torque estimation unit 33 processes the disturbance torque T by using the filter H2(s). d To find the slope torque T s .

[0040] In addition, the following transfer function G p (s), and each filter H1(s), H z (s) and H2(s) are described in detail.

[0041] exist Figure 5 An example of a dynamic model of an electric vehicle is shown in FIG. The following equations of motion 1 to 5 can be derived from the dynamic model shown in the figure.

[0042] [Mathematical formula 1]

[0043]

[0044] F=K t (r·ω w -V) (5)

[0045] In addition, each character in Formulas 1 to 5 includes the contents already described and is defined as follows.

[0046] J m : Inertia of the motor

[0047] J w : Inertia of the driving wheel

[0048] M: Vehicle mass

[0049] K D : Torsional rigidity of wheel drive system

[0050] K t : Coefficient related to the friction between the tire and the road

[0051] N: total transmission ratio

[0052] r: load radius of the tire

[0053] ω m : Mechanical angular velocity of the motor

[0054] T m : Motor torque

[0055] T D : Torque of the driving wheel

[0056] F: force applied to the vehicle

[0057] V: Vehicle speed

[0058] ω w : Angular velocity of the driving wheel

[0059] Referring to the above equations of motion 1 to 5, the transfer function G p (s) can be expressed by the following equation 6. In addition, each coefficient a1 to a4 and coefficient b0 to b3 in equation 6 is expressed by the following equations 7 to 14.

[0060] [Mathematical formula 2]

[0061]

[0062] a4=2J m J w M (7)

[0063] a3=J m (2J w +Mr 2 )K t(8)

[0064]

[0065] b3=2J w M (11)

[0066] b2=(2J w +Mr 2 )K t (12)

[0067] b1=MK D (13)

[0068] b0=K D K t (14)

[0069] Consider the transfer function G shown in the above equation 6 p The pole and zero of (s) indicate that one pole and one zero indicate very close values. This means that α and β in the following equation 15 indicate very close values.

[0070] [Mathematical formula 3]

[0071]

[0072] Therefore, by performing pole-zero cancellation approximating α=β in equation 15, a transfer function G in the form of (2nd order) / (3rd order) can be obtained as shown in equation 16 below: p (s).

[0073] [Formula 4]

[0074]

[0075] Next, the filter H1(s) is described. p From the viewpoint of setting (s) as a dedicated transfer function, the filter H1(s) is composed of a first-order low-pass filter defined by the following equation 17.

[0076] [Formula 5]

[0077]

[0078] The time constant τ1 is set to an appropriate value, for example, on the order of several tens of milliseconds, according to the torque response characteristics of the motor 5 .

[0079] Next, filter H z First, if the above equation 16 is rewritten, the following equation 18 is obtained.

[0080] [Mathematical formula 6]

[0081]

[0082] Among them, the coefficients of Formula 18 are determined by the following Formulas 19 to 23.

[0083] [Mathematical formula 7]

[0084]

[0085] In summary, the filter H is determined by the following formula 24 z (s).

[0086] [Mathematical formula 8]

[0087]

[0088] Among them, "ζ c " was determined to be higher than "ζ z "Small constant.

[0089] Next, the filter H2(s) is described. The filter H2(s) is configured to remove the disturbance torque T d Specifically, the filter H2(s) is composed of a first-order low-pass filter defined by the following equation 25.

[0090] [Mathematical formula 9]

[0091]

[0092] In addition, the time constant τ2 is set to an appropriate value of, for example, several hundred milliseconds in accordance with the assumed road surface conditions.

[0093] Next, return Figure 2 The upper limit torque limit request determination unit 34 is described below. The upper limit torque limit request determination unit 34 determines the gradient torque T s , Winding temperature T emp , RPM, and basic requested torque T1 as inputs to determine the restriction execution flag f lim .

[0094] Figure 6 : is a flowchart showing the processing of the upper limit torque limit request determination unit 34. As shown in the figure, the upper limit torque limit request determination unit 34 determines the gradient torque T in steps S110 to S140 respectively. s Is it the slope torque threshold T? s_th Above, winding temperature T emp Is it the temperature threshold T? emp_th Above, whether the vehicle speed V is within the low speed threshold V _loHigh speed threshold V _hi and whether the basic requested torque T1 is within the requested torque threshold T 1_th Furthermore, as for the upper limit torque limit request determination unit 34, if all the determination results are affirmative, the restriction execution flag f is set to lim Set to "1", if any one is negative, the execution flag f will be restricted lim Set to "0".

[0095] The vehicle body speed V used in the determination is calculated based on the following equation 26 according to the rotation speed RPM.

[0096] [Formula 10]

[0097]

[0098] Here, the gradient torque threshold value T used in S110 is s_th The appropriate grade torque T is determined as a reference for determining whether the grade is large enough to require execution of the upper limit of the basic request torque T1 (hereinafter, also referred to as "torque limit") (whether it is a steep uphill road). s In addition, the temperature threshold T used in S120 is emp_th As a judgement of the winding temperature T emp The criterion for whether the torque limit is required is determined as the appropriate winding temperature T emp The value of .

[0099] In addition, the low vehicle speed threshold V used in S130 _lo and high speed threshold V _hi As a reference for determining whether the vehicle speed of the electric vehicle during forward movement is within a predetermined vehicle speed range that requires execution of torque limitation, a value of an appropriate vehicle body speed V is determined.

[0100] Here, in the region where the vehicle speed V is below a certain value (low vehicle speed region), the electric vehicle cannot reach the desired vehicle speed or requires excessive time to reach the desired vehicle speed due to the execution of torque limitation, and thus, it is assumed that the driving time on the uphill road is prolonged. In this case, the motor 5 continues to output torque for a long time in the low vehicle speed region (low rotation speed region of the motor 5). Therefore, in the above-mentioned low vehicle speed region, it is assumed that the execution of torque limitation promotes the winding temperature T emp Considering this point, in this embodiment, the low vehicle speed threshold V _lo The value of the vehicle body speed V is determined to be appropriate from the viewpoint of determining a low vehicle speed region in which the execution of torque limitation should be prohibited. That is, the low vehicle speed threshold value V _loThe value is determined to be appropriate from the viewpoint of determining a low vehicle speed region in which an excessive temperature rise in the motor control system may be promoted due to execution of torque limitation.

[0101] On the other hand, it is assumed that the vehicle speed range (high vehicle speed range) in which the vehicle speed V is above a certain level is a small uphill road, and an excessive winding temperature T is not likely to occur. emp Therefore, if torque limitation is performed in such a scenario, although the possibility of excessive temperature rise in the motor control system is low, it is assumed that the acceleration performance of the electric vehicle is unnecessarily impaired. Considering this, in this embodiment, the high vehicle speed threshold V _hi The value of the vehicle body speed V is determined to be preferable from the viewpoint of determining a high vehicle speed region in which the execution of torque limitation should be prohibited. That is, the high vehicle speed threshold value V _hi The value is determined to be appropriate from the viewpoint of determining a high vehicle speed region in which the acceleration performance of the electric vehicle may be unnecessarily impaired due to execution of torque limitation.

[0102] Furthermore, in the vehicle speed range (medium vehicle speed range) other than the above-mentioned low vehicle speed range and high vehicle speed range, if the slope is large, an excessive winding temperature T may be generated. emp Therefore, in this embodiment, the execution of torque limitation is allowed in this scenario.

[0103] Furthermore, the requested torque threshold value T used in S140 1_th The reference value is determined to determine whether there is an acceleration request for the electric vehicle (based on the driver's acceleration intention).

[0104] Here, as a case where the basic request torque T1 becomes less than a certain value (inferred as a case where there is no acceleration intention), it is assumed that the driver does not operate the accelerator pedal, or after the accelerator pedal is turned on or off. m It is difficult to reach the winding temperature T emp In addition, after the accelerator pedal is turned on or off, the slope torque T is easily increased due to the pitch of the electric vehicle. s Therefore, in this scenario, based on the slope torque T s The calculated correction torque upper limit (the correction torque upper limit T lim ) may reduce the accuracy. Considering this point, in this embodiment, the requested torque threshold T 1_th The basic requested torque T1 is determined to be a value that is appropriate from the viewpoint of determining that there is no acceleration intention that should prohibit execution of torque limitation.

[0105] Then, the upper limit torque restriction request determination unit 34 outputs the set restriction execution flag f to the torque restriction unit 35. lim .

[0106] Next, the torque limiter 35 will be described.

[0107] Figure 7 This is a block diagram for explaining the structure of the torque limiting unit 35. lim If the limit execution flag f is "0" (when there is no upper limit torque limit request), the torque limiter 35 outputs the basic request torque T1 as the limited request torque T2 without changing the basic request torque T1. lim is "1" (when there is an upper limit torque limit request), the torque limiter 35 outputs the value obtained by combining the basic request torque T1 and the correction torque upper limit T lim The minimum value obtained is selected as the limited requested torque T2.

[0108] In addition, the torque limiting unit 35 uses the gradient torque T s And acceleration torque T acc The sum and maximum torque T max The minimum selection is used to calculate the corrected torque upper limit T lim In addition, the acceleration torque T acc The motor torque T is set to a value determined from the viewpoint of obtaining the minimum acceleration of the electric vehicle so as not to hinder traffic flow when traveling on an uphill road. m In particular, the acceleration torque T of this embodiment acc It is a fixed value determined in advance by experiments and is stored in a predetermined storage area that can be accessed by the motor controller 3 .

[0109] According to the control logic of the motor control method of the present embodiment described above, when the electric vehicle is traveling on an uphill road, the temperature parameter (winding temperature T emp ) and slope parameters (interference torque T d ) appropriately performs limitation of the upper limit of the basic requested torque T1.

[0110] return Figure 2 The vibration reduction control unit 36 ​​obtains the final requested torque T3 by executing a known process (such as that described in Japanese Patent No. 3508742) on the limited requested torque T2 to suppress the torsional vibration of the drive shaft 8, and outputs the final requested torque T3 to the torque control unit 37.

[0111] Furthermore, the torque control unit 37 determines the three-phase load command value D according to the known motor control logic (current vector control and voltage phase control, etc.) based on the final required torque T3 and other required input values.u , D v , D w .

[0112] In addition, Figure 8 Detailed Description of the Invention A flowchart showing the overall process in the motor control method according to the present embodiment described above is shown.

[0113] The configuration of the motor control method according to the present embodiment described above and the effects achieved thereby will be described.

[0114] In the present embodiment, a motor control method is provided for controlling the operation of the motor 5 based on a predetermined requested torque in an electric vehicle including the motor 5 as a driving source.

[0115] In the motor control method, a slope parameter (disturbance torque T d ), obtains a temperature parameter (winding temperature T emp ), at least one of the slope parameter and the temperature parameter is a predetermined threshold value (slope torque threshold value T s_th Or temperature threshold T emp_th ) or more, the upper limit of the requested torque is set to be smaller than the prescribed basic torque upper limit (maximum torque T max ) of the corrected torque upper limit T lim The torque limit processing (upper torque limit request determination unit 34 and torque limit unit 35) is performed.

[0116] In particular, in the torque limiting process, according to the slope parameter (disturbance torque T d ) determines the first torque (slope torque T s ), determine the second torque (acceleration torque T acc ), by referring to the first torque (slope torque T s ) and the second torque (acceleration torque T acc ) Correction of the basic torque upper limit (maximum torque T max ) to determine the corrected torque upper limit T lim .

[0117] Thus, when the electric vehicle is traveling on an uphill road, the upper limit of the basic request torque T1 can be appropriately limited according to the temperature in the motor control system and / or the size of the slope. Therefore, when traveling on an uphill road, it is possible to take into account both suppressing excessive temperature rise in the motor control system and ensuring the driving performance (acceleration performance) of the electric vehicle.

[0118] In particular, in this embodiment, the gradient torque T sThe acceleration torque T is determined to offset the force in the reverse direction when the vehicle is traveling uphill. acc is determined to obtain a torque that does not hinder the traffic flow. lim By determining the combined value of these, it is possible to more reliably achieve a balance between suppressing the temperature rise during uphill driving and ensuring the driving performance.

[0119] In the present embodiment, the output torque of the motor 5 (motor torque T m ) is the estimated value of the torque T est , and according to the rotation speed of the motor 5 (mechanical angular velocity ω m ) The estimated value of the disturbance determined is the disturbance torque T d To calculate the slope torque T s (gradient torque estimation unit 33).

[0120] Thus, the calculation of the slope torque T is realized. s In particular, the slope torque T can be calculated based on the signal that can be obtained in the vehicle drive system 100 without using a sensor for detecting the size of the slope. s .

[0121] In the present embodiment, when the vehicle speed parameter (vehicle body speed V) indicating the vehicle speed of the electric vehicle deviates from the predetermined vehicle speed range (V _lo ≤V≤V _hi ) in the case of slope torque T s Or winding temperature T emp and each specified threshold T s_th 、T emp_th Regardless of the size relationship, the upper limit of the requested torque is set to the maximum torque T max (No in S130 and S160).

[0122] Thus, after appropriately detecting a low vehicle speed region where the execution of torque limitation may promote excessive temperature rise in the motor control system, and a high vehicle speed region where excessive temperature rise itself is unlikely to occur and the need for torque limitation is low, the execution of torque limitation can be prohibited in these scenarios. Therefore, the execution of torque limitation can be limited to a medium vehicle speed region where excessive temperature rise in the motor control system is concerned, such as when driving on an uphill road with a large slope. As a result, the balance between suppressing excessive temperature rise when driving on an uphill road and ensuring the driving performance of the electric vehicle can be improved.

[0123] In addition, instead of prohibiting the execution of torque limitation in the low vehicle speed range and the high vehicle speed range, the execution of torque limitation may be permitted, but the limit value when the torque limitation is executed (i.e., the corrected torque upper limit T lim ) structure.

[0124] In particular, when the vehicle speed V deviates from the above vehicle speed range (V _lo ≤V≤V _hi ) can also be adjusted by adjusting the acceleration torque T acc The correction torque upper limit T lim In this case, the correction torque upper limit T can be set according to the vehicle body speed V. lim A structure whose size changes stepwise or continuously.

[0125] In the present embodiment, when the basic requested torque T1 determined based on the requested driving force for the electric vehicle is lower than a predetermined torque threshold (requested torque threshold T 1_th ) in the case of slope torque T s Or winding temperature T emp and each threshold T s_th 、T emp_th The upper limit of the requested torque is set to the maximum torque T max (No in S140 and S160).

[0126] Thus, by referring to the basic request torque T1, it is possible to appropriately identify a scenario where there is no advantage in executing torque limitation when driving uphill, that is, a scenario where excessive temperature rise in the motor control system is not likely to occur, and appropriately prohibit the execution of torque limitation in this scenario. Therefore, the execution of torque limitation can be limited to a torque region where excessive temperature rise in the motor control system is concerned. As a result, it is possible to achieve a better balance between suppressing excessive temperature rise when driving uphill and ensuring the driving performance of the electric vehicle.

[0127] In addition, when the basic requested torque T1 is lower than the requested torque threshold T 1_th In the case of the above, instead of prohibiting the execution of the upper torque limit, the execution of the torque limit may be allowed, but the correction torque upper limit T when the torque limit is executed may be appropriately adjusted. lim The size of the structure.

[0128] In particular, when the basic requested torque T1 determined according to the requested driving force for the electric vehicle is lower than the requested torque threshold T 1_th In the case of acc The correction torque upper limit T limIn this case, the correction torque upper limit T can be set according to the size of the basic request torque T1. lim A structure whose size changes stepwise or continuously.

[0129] Furthermore, in the present embodiment, a motor controller 3 that functions as a motor control device suitable for executing the motor control method is provided.

[0130] The motor controller 3 includes a gradient parameter acquisition unit (gradient torque estimation unit 33) for acquiring a gradient parameter (disturbance torque T d ); a temperature parameter acquisition unit (upper torque limit request determination unit 34) which acquires a temperature parameter (winding temperature T) indicating the temperature within the motor control system including the motor 5; emp ); the torque limiting unit 35, at least one of the slope parameter and the temperature parameter is a predetermined threshold value (slope torque threshold value T s_th Or temperature threshold T emp_th ) or more, the torque limiter 35 sets the upper limit of the requested torque to a value smaller than the predetermined basic torque upper limit (maximum torque T max ) of the corrected torque upper limit T lim Torque limiting process.

[0131] Specifically, the torque limiting unit 35 generates a torque limiting function based on the slope parameter (the disturbance torque T d ) determines the first torque (slope torque T s ), determine the second torque (acceleration torque T acc ), by referring to the first torque (slope torque T s ) and the second torque (acceleration torque T acc ) Correction of the basic torque upper limit (maximum torque T max ) to determine the corrected torque upper limit T lim .

[0132] [Second embodiment]

[0133] Hereinafter, the second embodiment will be described. Note that the same reference numerals are given to the same elements as those of the first embodiment, and the description thereof will be appropriately omitted.

[0134] Fig. 91 is a block diagram showing the main structure of a vehicle drive system 200 mounted on an electric vehicle. As shown in the figure, in the vehicle drive system 200 of the present embodiment, the motor controller 3 performs various operations using the vehicle body speed V of the electric vehicle detected by a vehicle speed sensor (not shown) and the longitudinal acceleration a1 detected by a longitudinal acceleration sensor (not shown) as inputs in addition to the various input values ​​described above, which is different from the first embodiment.

[0135] Fig.10 2 is a block diagram for explaining the configuration of the motor controller 3 according to the present embodiment. In the motor controller 3 according to the present embodiment, the gradient torque estimation unit 33 replaces the mechanical angular velocity ω m The gradient torque T is calculated by taking the vehicle speed V and the longitudinal acceleration a1 as inputs and limiting the requested torque T2. s .

[0136] Fig.11 is the slope torque T s Generally speaking, the driving force F acting on the tires of an electric vehicle, the vehicle weight M, the gravitational acceleration g, and the slope angle α of the road surface are in Fig.11 Therefore, the driving force F becomes the sum of the slope direction component of the gravitational acceleration and the actual acceleration (hereinafter also referred to as "vehicle acceleration a") excluding the influence of the slope acting on the vehicle body. Therefore, the relationship of the following formula 27 holds.

[0137] [Mathematical formula 11]

[0138] F=Ma-Mg·sinα (27)

[0139] On the other hand, the longitudinal acceleration a1 detected by the longitudinal acceleration sensor includes the influence of the gravitational acceleration corresponding to the slope angle α in addition to the vehicle body acceleration a. Therefore, the driving force F can be expressed by the product of the vehicle weight M and the longitudinal acceleration a1. Therefore, if "M×a1" is substituted into "F" of Formula 27 and both sides are divided by "M", the following Formula 28 is obtained.

[0140] [Mathematical formula 12]

[0141] a1=ag·sinα (28)

[0142] Furthermore, by rearranging equation 28, we obtain the following equation 29.

[0143] [Mathematical formula 13]

[0144] g·sinα=a-a1 (29)

[0145] The vehicle body acceleration a is calculated by differentiating the vehicle body speed V as shown in the following equation 30.

[0146] [Formula 14]

[0147]

[0148] In addition, the torque that cancels the force acting on the electric vehicle in the retreating direction due to the slope (ie, the slope torque T s ) can be expressed by the following formula 31.

[0149] [Mathematical formula 15]

[0150]

[0151] Therefore, if equation 29 is substituted into equation 31, the following equation 32 is obtained.

[0152] [Formula 16]

[0153]

[0154] Fig.12 2 is a block diagram for explaining the configuration of the gradient torque estimation unit 33. As shown in the figure, the gradient torque estimation unit 33 includes an acceleration calculation unit 331, a subtraction calculation unit 332, and a gain unit 333.

[0155] The acceleration calculation unit 331 calculates the vehicle body acceleration a from the amount of change in the vehicle body speed V per time according to equation 30 and outputs it to the subtraction unit 332. The subtraction unit 332 calculates the gradient acceleration a corresponding to the influence of the gravity acceleration corresponding to the gradient by subtracting the longitudinal acceleration a1 from the vehicle body acceleration a according to equation 29. s (=gsinα) and outputs it to the gain unit 333. The gain unit 333 calculates the slope acceleration a according to equation 31. s Multiply the vehicle weight M, the total transmission ratio N, the gain Mr / N determined according to the load radius r of the driving wheels 9a, 9b and add the slope acceleration a s Convert to torque equivalent value and output it as slope torque T s .

[0156] return Fig.11 The upper limit torque limit request determination unit 34 of this embodiment uses the gradient torque T s and winding temperature T emp As input to determine the acceleration torque T acc .

[0157] Fig.13 It indicates the determination of the acceleration torque T acc As shown in the figure, the acceleration torque Tacc is determined as the winding temperature T emp The lower the slope, the torque T s The smaller the acceleration torque T acc The larger the value is. In addition, the map is pre-stored in a predetermined storage area accessible to the motor controller 3. In addition, the map may be configured in a form that is preferably selected from the viewpoint of arithmetic processing, such as a linear complementary lookup table or a function with conditional determination.

[0158] The upper-limit torque limit request determination unit 34 can determine the upper-limit torque limit request based on the winding temperature T by referring to the above map. emp and slope torque T s Determine the appropriate acceleration torque T for pre-schedule acc .

[0159] Furthermore, in Fig.14 , a block diagram for explaining the structure of the torque limiter 35 of the present embodiment is shown. As shown in the figure, the torque limiter 35 replaces the fixed value acceleration torque T described in the first embodiment. acc , and the variable acceleration torque T calculated by the upper torque limit request determination unit 34 is acc Subsequent operations are performed similarly as input.

[0160] In addition, Fig.15 , a flowchart showing the overall processing in the motor control method according to the above-mentioned present embodiment is shown.

[0161] The configuration of the motor control method according to the present embodiment described above and the effects achieved thereby will be described.

[0162] In this embodiment, the first torque (slope torque T ) is determined based on the longitudinal acceleration a1 of the electric vehicle and the rate of change (body acceleration a) of the body speed parameter (body speed V) indicating the longitudinal speed of the body of the electric vehicle. s )(Formula 30 to Formula 32).

[0163] In this way, the slope torque T can be calculated by using the detection values ​​of the sensor (G sensor) for detecting the actual front and rear acceleration of the electric vehicle and the vehicle speed sensor according to the change of the driving resistance when driving uphill and the change of the driving force F acting on the vehicle body (brake operation, etc.). s Determine the appropriate size.

[0164] In addition, in this embodiment, based on the temperature parameter (winding temperature T emp ) and slope parameters (slope torque T s ) determines the second torque (acceleration torque T acc ).

[0165] Therefore, the winding temperature T emp and / or the size of the slope, appropriately determine the acceleration torque T acc More specifically, at a winding temperature T emp In situations where the possibility of excessive temperature rise in the motor control system is low, such as when the speed is relatively low or the slope is relatively small, the acceleration torque T acc The larger value is set to more reliably maintain the running performance of the electric vehicle.

[0166] Alternatively, the winding temperature T emp and slope torque T s The acceleration torque T is determined by referring to at least one of the above, or in addition to the above, a vehicle speed parameter indicating the vehicle speed of the electric vehicle (such as the vehicle body speed V). acc structure.

[0167] Thus, the second torque (acceleration torque T acc ). More specifically, for example, in a low vehicle speed region where the vehicle speed is below a certain value, by increasing the acceleration torque T acc Setting it relatively large enables the electric vehicle to smoothly join the traffic flow when starting (accelerating from a stop to a certain speed). In addition, in the medium and high speed range where the vehicle speed is above a certain level, by increasing the acceleration torque T acc By setting it relatively small, it is possible to suppress excessive acceleration after the vehicle speed transitions from the low vehicle speed region to the medium and high vehicle speed region, and suppress excessive temperature rise in the motor control system.

[0168] [Control results]

[0169] Hereinafter, the control result of the motor control method (embodiment) according to the above-mentioned embodiment will be compared with the control result of the motor control method according to the comparative example and described. Figure 7 or Fig.10 The control method of the embodiment differs in that the upper limit torque limit request determination unit 34 and the torque limit unit 35 perform processing to output the basic request torque T1 directly to the vibration reduction control unit 36 ​​without changing. A common control method is assumed for other structures.

[0170] Fig.16 is a graph showing various control results based on the comparative example and the embodiment. Fig.16 In FIG. 1 , it is assumed that the electric vehicle continues to travel on an uphill road for a predetermined period of time. Fig.16 (a) shows the control results of the comparative example. Fig.16 (b) shows the control result of the embodiment.

[0171] As shown in the figure, under the control of the embodiment, the motor torque T after the start of the limitation of the upper limit torque (t=t1) is suppressed compared with the control of the comparative example. m As a result, the winding temperature T emp The maximum value of the winding temperature T emp The maximum value of the decrease (in the figure, indicated by the reference symbol "ΔT emp ”). On the other hand, in the embodiment, the vehicle speed after the restriction starts (t=t1) is slightly reduced compared to the comparative example, but is maintained within a range that does not impair the driving performance requested when driving on an uphill road.

[0172] Therefore, in the control of the embodiment, it is possible to achieve both ensuring the running performance during uphill running and suppressing an excessive temperature increase.

[0173] Although the embodiments of the present invention have been described above, the configurations described in the above embodiments and modifications are merely examples of application of the present invention and are not intended to limit the technical scope of the present invention.

[0174] For example, in the above-mentioned embodiments, the winding temperature T detected by the thermistor 23 is used. emp The temperature parameter indicating the temperature in the motor control system is described as an example. However, the temperature parameter is not limited to this, and any other parameter can be used as long as it can indicate the temperature change in the motor control system corresponding to the gradient of the uphill road. For example, the magnet temperature of the motor 5, the temperature of the power semiconductor element in the PWM inverter 4, and / or the temperature of the battery 1 can also be used as the temperature parameter.

[0175] Furthermore, the structures of the first embodiment and the second embodiment may be appropriately combined within the range that they do not contradict each other. For example, the winding temperature T described in the second embodiment may be determined. emp , Slope torque T s , and the vehicle body speed V, at least one of which is a variable acceleration torque T acc The operation logic of the first embodiment is replaced by determining the fixed value of the acceleration torque T acc The calculation logic of is applied to the motor control method of the first embodiment. In addition, the gradient torque T described in the second embodiment may also be s The estimation logic of is replaced by the disturbance torque T described in the first embodiment. d Determine the slope torque T s The operation logic is applied to the motor control method of the first embodiment.

Claims

1. A motor control method, in an electric vehicle having a motor as a driving source, controlling the operation of the motor based on a predetermined requested torque, wherein: obtaining a slope parameter indicating the slope of a road surface for the electric vehicle, obtaining a temperature parameter indicative of a temperature within a motor control system including the motor, When at least one of the gradient parameter and the temperature parameter is equal to or greater than a predetermined threshold value, a torque limiting process is performed to set the upper limit of the requested torque to a modified torque upper limit that is smaller than a predetermined basic torque upper limit. In the torque limiting process, determining a first torque according to the slope parameter, determining a second torque for imparting a predetermined acceleration to the electric vehicle, The modified torque upper limit is determined by modifying the basic torque upper limit with reference to the first torque and the second torque.

2. The motor control method according to claim 1, wherein: The first torque is calculated based on an estimated value of the output torque of the electric motor and an estimated value of a disturbance determined based on a rotation speed of the electric motor.

3. The motor control method according to claim 1, wherein: The first torque is determined based on the longitudinal acceleration of the electric vehicle and a rate of change of a vehicle body speed parameter indicating a longitudinal speed of a vehicle body of the electric vehicle.

4. The motor control method according to any one of claims 1 to 3, wherein: The second torque is determined based on at least any one of the temperature parameter, a vehicle speed parameter indicating a vehicle speed of the electric vehicle, and the slope parameter.

5. The motor control method according to claim 1, wherein: When a vehicle speed parameter indicating the vehicle speed of the electric vehicle deviates from a predetermined vehicle speed range, Regardless of the magnitude relationship between the gradient parameter or the temperature parameter and each of the predetermined threshold values, the upper limit of the requested torque is set to the basic torque upper limit or the second torque is adjusted to make the correction torque upper limit larger.

6. The motor control method according to claim 1, wherein: When a basic requested torque determined based on a requested driving force for the electric vehicle is lower than a prescribed torque threshold, Regardless of the magnitude relationship between the slope parameter or the temperature parameter and the prescribed threshold value, the upper limit of the requested torque is set to the basic torque upper limit or the second torque is adjusted to make the correction torque upper limit larger.

7. A motor control device for controlling the operation of the motor based on a predetermined requested torque in an electric vehicle having a motor as a driving source, wherein: The motor control device has: a slope parameter acquisition unit configured to acquire a slope parameter indicating a road surface slope of the electric vehicle; a temperature parameter acquisition unit that acquires a temperature parameter indicating a temperature in a motor control system including the motor; a torque limiting unit for executing a torque limiting process for setting the upper limit of the requested torque to a modified torque upper limit that is smaller than a prescribed basic torque upper limit when at least one of the slope parameter and the temperature parameter is equal to or greater than a prescribed threshold value, respectively prescribed; The torque limiter determines a first torque based on the gradient parameter and determines a second torque for providing a predetermined acceleration to the electric vehicle, and determines the modified torque upper limit by modifying the basic torque upper limit with reference to the first torque and the second torque.

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