Vehicle control device and vehicle control method

Abstract

The present invention provides a vehicle control device and a vehicle control method capable of suppressing unnecessary torque restriction. The state estimation unit of this vehicle control device estimates the current state quantity of a motor on the basis of driving state information. The state prediction unit predicts a future state quantity of the motor on the basis of the driving state information and the current state quantity. The cooling amount control instruction unit controls a cooling circuit for cooling the motor on the basis of the future state quantity. The torque control instruction unit controls the torque of the motor on the basis of the future state quantity. The state prediction unit makes a period up to the future (N2 time) when predicting the future state quantity to be output to the torque control instruction unit shorter than a period up to the future (N1 time) when predicting the future state quantity to be output to the cooling amount control instruction unit.

Description

Vehicle control device and vehicle control method

[0001] The present invention relates to a vehicle control device and a vehicle control method.

[0002] A technology for cooling a vehicle motor is described, for example, in Patent Document 1. The motor control device described in Patent Document 1 predicts (estimates) the temperatures of the magnets and motor coils and changes the flow rate of refrigerant in the cooling circuit according to the predicted temperatures. The motor control device also limits the upper torque limit of the motor according to the predicted temperatures.

[0003] Japanese Patent Application Laid-Open No. 2023-53765

[0004] However, the motor control device described in Patent Document 1 controls the motor torque and the cooling circuit flow rate independently, which can result in unnecessary torque restriction in motor torque control without considering the effect of cooling circuit flow rate control.

[0005] In consideration of the above problems, an object of the present invention is to provide a vehicle control device and a vehicle control method that can suppress unnecessary torque limitation.

[0006] In order to solve the above problems and achieve the object of the present invention, a vehicle control device according to one aspect of the present invention includes a state estimation unit, a state prediction unit, a cooling amount control instruction unit, and a torque control instruction unit. The state estimation unit acquires operating state information including parameters related to the temperature of the motor, and estimates a current state quantity of the motor based on the operating state information. The state prediction unit predicts a future state quantity of the motor based on the operating state information and the current state quantity. The cooling amount control instruction unit controls a cooling circuit for cooling the motor based on the future state quantity. The torque control instruction unit controls the torque of the motor based on the future state quantity. The state prediction unit sets a future period when predicting the future state quantity to be output to the torque control instruction unit to be shorter than a future period when predicting the future state quantity to be output to the cooling amount control instruction unit.

[0007] In one aspect of the present invention, a vehicle control method includes a state estimation unit that acquires driving state information including parameters related to the temperature of the motor and estimates a current state quantity of the motor based on the driving state information. Next, a state prediction unit predicts a future state quantity of the motor based on the driving state information and the current state quantity. A cooling amount control instruction unit controls a cooling circuit for cooling the motor based on the future state quantity. Furthermore, a torque control instruction unit controls the torque of the motor based on the future state quantity. The state prediction unit then sets a future period when predicting the future state quantity to be output to the torque control instruction unit to be shorter than a future period when predicting the future state quantity to be output to the cooling amount control instruction unit.

[0008] According to the vehicle control device and vehicle control method configured as described above, unnecessary torque limitation can be suppressed. Note that problems, configurations, and effects other than those described above will become clear from the following description of the embodiments.

[0009] FIG. 1 is an overall configuration diagram showing an example of a basic configuration of a vehicle according to one embodiment; FIG. 2 is a schematic configuration diagram showing the configuration of a motor, a cooling circuit, etc. according to one embodiment; FIG. 3 is a functional block diagram of a control unit according to one embodiment; FIG. 4 is a flowchart showing an example of a vehicle control process according to one embodiment; FIG. 5 is a diagram showing the relationship between the flow rate and heat transfer coefficient of the first refrigerant when the temperature of the first refrigerant changes according to one embodiment; FIG. 6 is a time history temperature result comparing the torque and temperature of a motor according to one embodiment and a conventional technology; and FIG. 7 is a time history result comparing the torque and temperature, and the flow rate and temperature of the cooling circuit of a motor according to one embodiment and a conventional technology.

[0010] A vehicle control device and a vehicle control method according to an embodiment of the present invention will be described below. Note that common members in the various drawings are given the same reference numerals.

[0011] [Configuration of the Vehicle] First, the overall configuration of a vehicle equipped with a motor and a cooling circuit will be described with reference to Fig. 1. Fig. 1 is an overall configuration diagram showing an example of the basic configuration of a vehicle according to one embodiment.

[0012] 1, the vehicle 100 includes a motor 101, a transmission 102, a differential gear 103, a drive shaft 104, and wheels 105. The vehicle 100 also includes a first cooling circuit, a second cooling circuit, and a third cooling circuit.

[0013] The motor 101 is a power source for driving the vehicle 100. The power output by the motor 101 is transmitted to wheels 105 via a transmission 102, a differential gear 103, and a drive shaft 104. The number of motors 101 provided in the vehicle 100 is not limited to one, and may be, for example, two, four, or more.

[0014] The first cooling circuit includes a first pipe 106, a heat exchanger 107, and a first refrigerant pump 108. The motor 101 is connected to the heat exchanger 107 via the first pipe 106. The first refrigerant pump 108 pumps the first refrigerant in the first pipe 106. As a result, the first refrigerant is sent to the heat exchanger 107.

[0015] The second cooling circuit has a second refrigerant pump 111, a radiator 112, a second pipe 113, and a heat exchanger 107. The second cooling circuit cools the inverter 110. The inverter 110 is connected to the heat exchanger 107 and the radiator 112 via the second pipe 113. The second refrigerant pump 111 pumps the second refrigerant in the second pipe 113. As a result, the second refrigerant is sent to the heat exchanger 107 and the radiator 112.

[0016] When the inverter 110 receives DC power from the battery 109, it operates a switching element to convert the DC power into AC power. The inverter 110 supplies AC power to the motor 101. When the inverter 110 receives a signal from the motor 101, it operates a switching element to convert the AC regenerative power of the motor 101 into DC power. The inverter 110 charges the battery 109 with the converted DC power. The battery 109 is, for example, a secondary battery such as a lithium-ion battery.

[0017] The radiator 112 exchanges heat with outside air to cool the second refrigerant and a third refrigerant, which will be described later. A radiator fan 114 is attached to the radiator 112. The rotation speed of the radiator fan 114 is controlled by a control unit 250 (see FIG. 2), which will be described later. The control unit 250 controls the amount of heat exchange by the radiator 112 by changing the rotation speed of the radiator fan 114.

[0018] The third cooling circuit has a radiator 112, a third refrigerant pump 115, and a third pipe 116. The third cooling circuit cools the battery 109. The battery 109 is connected to the radiator 112 via the third pipe 116. The third refrigerant pump 115 pumps the third refrigerant in the third pipe 116. As a result, the third refrigerant is sent to the radiator 112.

[0019] [Configuration of Motor and Cooling Circuit] Next, the motor 101, inverter 110, battery 109, first cooling circuit, second cooling circuit, and their control systems will be described with reference to Fig. 2. Fig. 2 is a schematic diagram showing the configuration of the motor 101, the cooling circuit, etc.

[0020] As shown in FIG. 2 , the motor 101 includes a housing 201 , a stator 202 , a rotor 203 , and a shaft 204 .

[0021] The stator 202 is fitted inside the housing 201. The stator 202 has a stator core 205 made of laminated magnetic material and a stator coil 206 wound around the stator core 205. The rotor 203 is installed on the inner periphery of the stator 202. The rotor 203 has a rotor core 207 made of laminated magnetic material and a magnet 208 embedded inside the rotor core 207 on the outer periphery side.

[0022] The shaft 204 is integrated with the rotor 203. A rotation angle resolver (not shown) is attached to one end of the shaft 204. The rotation angle resolver detects the number of rotations and the rotation angle of the shaft 204. A bearing 201a is attached to the housing 201. The bearing 201a supports the shaft 204 so that it can rotate.

[0023] The inverter 110 operates a switching element to convert DC power sent from the battery 109 into AC power. The inverter 110 supplies the converted AC power to the motor 101. When a current is applied to the stator coil 206 of the motor 101, a rotating magnetic field and the magnetic attraction force of the magnet 208 act to generate axial torque in the rotor 203. This causes the rotor 203 and the shaft 204 to rotate.

[0024] The speed of vehicle 100 required by the driver (required speed) is calculated from, for example, the amount of operation of an accelerator pedal (not shown) or a brake pedal (not shown). Control unit 250 calculates the torque required of motor 101 (required torque) based on the required speed. Control unit 250 generates a command for controlling the amount of current supplied to stator coil 206 in accordance with the calculated required torque, and outputs the command to inverter 110.

[0025] When current is applied to the stator coil 206, a portion of the power is lost and converted into heat in the stator coil 206. Furthermore, when the rotor core 207 rotates, eddy currents are generated inside the rotor core 207. The loss due to the eddy currents is converted into heat in the rotor core 207. The heat generated by the stator coil 206 and the rotor core 207 heats the stator 202, the rotor 203, the magnets 208, etc. As a result, the temperature of the motor 101 rises.

[0026] The first cooling circuit releases heat generated in the motor 101 to the outside of the motor 101. The first refrigerant pumped by the first refrigerant pump 108 passes through a heat exchanger 107 and is supplied to a housing 201 of the motor 101. The first refrigerant then absorbs heat from the stator 202 and the rotor 203 via the housing 201. This cools the stator 202 and the rotor 203.

[0027] The first refrigerant that has absorbed heat from the stator 202 and the rotor 203 returns to the first refrigerant tank 118. In the first refrigerant tank 118, the first refrigerant is cooled by heat exchange with outside air. The heat of a portion of the first refrigerant that has not been cooled in the first refrigerant tank 118 is transferred to the second cooling circuit when the first refrigerant is pumped by the first refrigerant pump 108 and passes through the heat exchanger 107. This cools the first refrigerant.

[0028] In this embodiment, the stator 202 and the rotor 203 are cooled via the housing 201. However, the cooling of the motor according to the present invention is not limited to this, and for example, a direct-cooling type motor may be adopted to directly cool the stator and rotor.

[0029] Here, we will explain the necessity of cooling the motor 101. If the temperature of the magnet 208 exceeds the allowable upper limit, irreversible demagnetization occurs, in which the magnetic force does not return to its original characteristics even if the temperature of the magnet 208 subsequently drops. As a result, the magnetic field generated by the current flowing through the stator coil 206 weakens, and the performance of the motor 101 deteriorates.

[0030] Furthermore, if the temperature of the stator coil 206 exceeds the allowable upper limit, the insulating coating covering the stator coil 206 will be damaged, causing an electrical short circuit in the motor 101. Therefore, it is important to control the flow rate and temperature of the first refrigerant in the first cooling circuit and the amount of electricity (i.e., torque) supplied to the motor 101 so that the temperature of the stator coil 206 and the temperature of the magnet 208 do not exceed the upper limit.

[0031] The second cooling circuit releases heat generated in the inverter 110 to the outside of the inverter 110. As described above, the second cooling circuit also cools the second refrigerant. The second refrigerant pumped by the second refrigerant pump 111 passes through the heat exchanger 107 and is supplied to the housing (not shown) of the inverter 110. The second refrigerant then absorbs heat from the inverter 110 via the housing. This cools the inverter 110.

[0032] The second refrigerant that has absorbed heat from inverter 110 passes through radiator 112 and returns to second refrigerant tank 119. In radiator 112 and second refrigerant tank 119, the second refrigerant is cooled by heat exchange with outside air. The temperature of the second refrigerant in second refrigerant tank 119 is lower than the temperature of the first refrigerant in first refrigerant tank 118.

[0033] The control unit 250 corresponds to a vehicle control device according to the present invention. The control unit 250 controls the driving of the motor 101, the first refrigerant pump 108, the second refrigerant pump 111, the third refrigerant pump 115, the inverter 110, and the radiator fan 114. The control unit 250 has a state estimation unit 251, a state prediction unit 252, a calculation unit 253, and a control instruction unit 254.

[0034] [Functional Configuration of Control Unit] Next, the functional configuration of the control unit 250 will be described with reference to Fig. 3. Fig. 3 is a functional block diagram of the control unit 250.

[0035] 3 , the actual temperature of motor 101, the torque value of motor 101, the rotation speed of motor 101, the flow rate of the first refrigerant, and the temperature of the first refrigerant are input to state estimation unit 251 of control unit 250. The motor temperature is temperature information of motor 101 output from a sensor (e.g., a thermocouple) attached to stator coil 206.

[0036] The actual temperature, torque value, and rotation speed of motor 101, and the flow rate and temperature of the first refrigerant correspond to operating state information according to the present invention. The operating state information according to the present invention may also be the amount of power supplied to motor 101 or the outside air temperature. The operating state information according to the present invention may include at least one parameter selected from the actual temperature, torque value, and rotation speed of motor 101, the flow rate and temperature of the first refrigerant, the amount of power supplied to motor 101, and the outside air temperature.

[0037] The state estimation unit 251 has a heat generation amount map (loss map), a heat transfer coefficient map, and a prediction model. The heat generation amount map defines the heat generation amount of each part (e.g., stator coil 206, stator core 205, rotor core 207, etc.) according to the rotation speed of motor 101, the torque of motor 101, the frequency of inverter 110, etc. The heat transfer coefficient map defines the heat transfer coefficient of parts (housing 201, etc.) that exchange heat with the first refrigerant according to the temperature and flow rate of the first refrigerant. The prediction model includes a system matrix A, an input matrix B, and an output matrix C of a state equation described below.

[0038] The state estimation unit 251 determines the motor loss u (input vector u) and the heat transfer coefficient h by referring to the heat generation amount map and the heat transfer coefficient map. The heat transfer coefficient h corresponds to the actual transfer coefficient according to the present invention. The control unit 250 estimates the state quantity x (temperature distribution of each part) using the input vector u, the heat transfer coefficient h, and the state equation. The control unit 250 can estimate the state quantity x using, for example, a Kalman filter. The state estimation unit 251 sends the state quantity x, the heat transfer coefficient h, and the motor loss u to the state prediction unit 252.

[0039] The state prediction unit 252 includes a first state prediction unit 252a and a second state prediction unit 252b. The first state prediction unit 252a predicts a state at a future time N based on a state quantity x, a heat transfer coefficient h, and an input vector u. １ The first state prediction unit 252a predicts the state quantity x (temperature of each part) at time N １ The state quantity x is sent to the calculation unit 253.

[0040] The second state prediction unit 252b predicts the state at a future time N based on the state quantity x, the heat transfer coefficient h, and the input vector u. ２ For example, the state quantity x (temperature of each part) at time N １ is time N ２ The second state prediction unit 252b sets the time later than time N ２ The state quantity x is sent to the calculation unit 253.

[0041] In this way, the state estimation unit 251 uses values ​​detected by various sensors to estimate the state quantity x. This allows the current state quantity x to be estimated from values ​​detected by a limited number of sensors. Then, the state prediction unit 252 can use the state quantity x to accurately predict the future state quantity x.

[0042] For example, the magnet 208 is located inside the rotor 203, which rotates at high speed. Therefore, it is difficult to measure the temperature of the magnet 208. The state estimation unit 251 can estimate the current temperature of the magnet 208, which is difficult to measure, from values ​​detected by various sensors. Furthermore, the state prediction unit 252 can predict the future temperature of the magnet 208 based on the current temperature of the magnet 208.

[0043] The calculation unit 253 includes a heat transfer coefficient calculation unit 253a, a first refrigerant temperature calculation unit 253b, a heat generation amount calculation unit 253c, and a first refrigerant flow rate calculation unit 253d. １ The heat transfer coefficient manipulated variable Δh is calculated based on the state variable x of the heat transfer coefficient control system 100. The heat transfer coefficient manipulated variable Δh corresponds to the required heat transfer coefficient according to the present invention. The heat transfer coefficient manipulated variable Δh is one of the physical quantities required to specify manipulated variables such as the flow rates of the first and second refrigerants and the rotation speed of the radiator fan 114.

[0044] The first refrigerant temperature calculation unit 253b calculates the first refrigerant temperature at time N １ The first refrigerant temperature manipulated variable ΔTf is calculated based on the state variable x and the heat transfer coefficient manipulated variable Δh in the heat transfer coefficient. The first refrigerant temperature manipulated variable ΔTf is one of the physical quantities described above, and is calculated based on the target temperature of the first refrigerant at the inlet of the motor 101. The heat generation amount calculation unit 253c calculates the first refrigerant temperature manipulated variable ΔTf based on the state variable x and the heat transfer coefficient manipulated variable Δh in the heat transfer coefficient. The first refrigerant temperature manipulated variable ΔTf is one of the physical quantities described above, and is calculated based on the target temperature of the first refrigerant at the inlet of the motor 101. ２ The allowable heat generation amount Δu is calculated based on the state quantity x after the time and the heat transfer coefficient manipulated variable Δh. The allowable heat generation amount Δu is the allowable heat generation amount of each part of the motor 101. The first refrigerant flow rate calculation unit 253d calculates the target flow rate of the first refrigerant based on the heat transfer coefficient manipulated variable Δh.

[0045] The control instructing unit 254 has a first cooling amount control instructing unit 254a, a second cooling amount control instructing unit 254b, and a torque control instructing unit 254c. The first cooling amount control instructing unit 254a determines the rotation speed of the first refrigerant pump 108 based on the target flow rate of the first refrigerant and the actual flow rate of the first refrigerant. The first cooling amount control instructing unit 254a controls the operation of the first refrigerant pump 108 in accordance with the determined rotation speed of the first refrigerant pump 108.

[0046] Second cooling amount control instructing unit 254b determines the rotation speed of radiator fan 114 and the rotation speed of second refrigerant pump 111 based on the first refrigerant temperature manipulated variable ΔTf, the temperature of the second refrigerant, and the temperature of the first refrigerant. Second cooling amount control instructing unit 254b controls the drive of radiator fan 114 in accordance with the determined rotation speed of radiator fan 114. Second cooling amount control instructing unit 254b controls the drive of second refrigerant pump 111 in accordance with the determined rotation speed of second refrigerant pump 111.

[0047] The torque control instruction unit 254c determines the torque limit value or the limit value of the amount of current flowing through the motor 101 based on the allowable heat generation amount Δu and the torque value of the motor 101. The torque control instruction unit 254c controls the torque (amount of current flowing through the motor 101) in consideration of the torque limit value so that the temperature of each part of the motor 101 is equal to or lower than the upper limit value.

[0048] Generally, the motor, refrigerant pump, and radiator fan are controlled independently. Therefore, motor torque control may limit torque at unnecessary times. As a result, motor torque control may degrade vehicle performance. In this embodiment, vehicle control processing is performed that coordinates the control of the motor, refrigerant pump, and radiator fan, thereby suppressing unnecessary torque limiting.

[0049] [Vehicle Control Processing] Next, the vehicle control processing performed by the control unit 250 will be described with reference to Fig. 4. Fig. 4 is a flowchart showing an example of the vehicle control processing according to an embodiment.

[0050] First, the state estimation unit 251 of the control unit 250 acquires the temperature sensor value Tmeas of the motor 101 (S401). Next, the state estimation unit 251 acquires the rotation speed of the motor 101, the torque of the motor 101, the flow rate of the first refrigerant, and the temperature of the first refrigerant (S402).

[0051] Next, the state estimation unit 251 refers to the heat generation map and calculates the heat generation amount u (input vector u) of each part of the motor 101 based on the rotation speed of the motor 101, the torque of the motor 101, and the frequency of the inverter 110 (S403).

[0052] In step S403, the state estimation unit 251 refers to the heat transfer coefficient map and calculates the heat transfer coefficient h (current heat transfer coefficient h) of each part of the motor 101 based on the rotation speed of the motor 101, the temperature of the first refrigerant, and the flow rate of the first refrigerant. ｍａｘ Calculate the following.

[0053] Next, the state estimation unit 251 calculates the state quantity x ｋis estimated (S404). The state equation at time k can be expressed by the following equation (1): In equation (1), A is a system matrix, B is an input coefficient matrix, u is an input vector, and Acnv is an area matrix of a prediction model in which heat transfer is performed.

[0054]

[0055] Here, assuming that the nonlinear term of the heat transfer coefficient part is constant from the kth step to the next step, linearization results in the following equation (2).

[0056]

[0057] Then, by substituting equation (2) into equation (1) and applying the Kalman filter, the state quantity x is calculated as shown in the following equations (3) to (8). ｋ can be estimated.

[0058]

[0059] Next, the first state prediction unit 252a of the control unit 250 predicts the state at a future time N １ The first state prediction unit 252a predicts the temperature e1 of each part of the motor 101 at step S405. ｋ The temperature e1 can be expressed by the following equations (9) and (10).

[0060]

[0061] In this way, the first state prediction unit 252a uses the formulas (9) and (10) to predict the future time N １ The temperature y of each part of the motor 101 at ｔ＋Ｎ１ The various parts of the motor 101 are, for example, the housing 201, the stator coil 206, the rotor core 207, the magnet 208, and other components.

[0062] Next, the heat transfer coefficient calculation unit 253a of the control unit 250 calculates the heat transfer coefficient at time N １The optimum heat transfer coefficient manipulated variable Δh is calculated based on the difference between the temperature of each part of the motor 101 at time (hereinafter referred to as the "predicted temperature") and the target temperature r (S406). The target temperature r corresponds to the motor target temperature according to the present invention.

[0063] The optimal heat transfer coefficient manipulated variable Δh can be calculated by reducing it to a quadratic programming problem, as shown in the following equations (11) to (16). At this time, the heat transfer coefficient calculation unit 253a can calculate the optimal heat transfer coefficient manipulated variable Δh under the constraint conditions by taking into account the constraint conditions. Examples of the constraint conditions include the rotation speed of the radiator fan 114 and the limit heat transfer coefficient determined by the limit value of the flow rate of the first coolant pump 108. Known methods for taking into account the constraint conditions include the active set method (effective constraint method). Note that the above method is merely an example and is not limited to this.

[0064]

[0065]

[0066]

[0067] Next, the heat transfer coefficient calculation unit 253a calculates the heat transfer coefficient h, which is the sum of the heat transfer coefficient manipulated variable Δh and the current heat transfer coefficient h. ｖａｒ Then, the heat transfer coefficient calculation unit 253a calculates the heat transfer coefficient h ｖａｒ is the maximum heat transfer coefficient h ｍａｘ In step S407, it is determined whether the heat transfer coefficient h ｖａｒ is the maximum heat transfer coefficient h ｍａｘ If it is determined that the number is not equal to or greater than the predetermined number (NO in S407), the control unit 250 proceeds to step S415.

[0068] Heat transfer coefficient h ｖａｒ is the maximum heat transfer coefficient h ｍａｘIf the target flow rate of the first refrigerant is not equal to or greater than the limit flow rate of the first refrigerant, this means that the target flow rate of the first refrigerant is not equal to or greater than the limit flow rate of the first refrigerant. The limit flow rate of the first refrigerant is determined according to the pumping capacity of the first refrigerant pump 108. If the target flow rate of the first refrigerant is not equal to or greater than the limit flow rate of the first refrigerant, the control unit 250 proceeds to step S415 and controls the drive of the first refrigerant pump 108 to set the flow rate of the first refrigerant to the target flow rate.

[0069] On the other hand, the heat transfer coefficient h ｖａｒ is the maximum heat transfer coefficient h ｍａｘ If the target flow rate of the first refrigerant is equal to or greater than the limit flow rate of the first refrigerant, this means that the target flow rate of the first refrigerant is equal to or greater than the limit flow rate of the first refrigerant. In other words, the first refrigerant pump 108 cannot make the flow rate of the first refrigerant reach the target flow rate. If the target flow rate of the first refrigerant is equal to or greater than the limit flow rate of the first refrigerant, the control unit 250 performs control to lower the temperature of the first refrigerant via the second refrigerant.

[0070] In step S407, the heat transfer coefficient h ｖａｒ is the maximum heat transfer coefficient h ｍａｘ When it is determined that the first refrigerant temperature is equal to or greater than the critical minimum temperature Tf (YES in S407), the heat transfer coefficient calculation unit 253a outputs a maximum value determination flag to the first refrigerant temperature calculation unit 253b. ｍｉｎ is calculated (S408).

[0071] Next, the first refrigerant temperature calculation unit 253b calculates the state quantity x estimated in step S404. ｋ From the above, the optimum temperature Tf of the first refrigerant at the inlet of the motor 101 is ｔａｒ In step S409, the first refrigerant temperature calculation unit 253b determines the target temperature (S409). １ Based on the difference between the predicted temperature and the target temperature r, an optimal temperature manipulated variable ΔTf for the first refrigerant (first refrigerant temperature manipulated variable ΔTf) is calculated. １ The predicted temperature of takes into consideration the heat transfer coefficient manipulated variable Δh calculated in step S406.

[0072] The first refrigerant temperature manipulated variable ΔTf can be calculated by solving a quadratic programming problem as shown in the following equations (17) to (22). At this time, the first refrigerant temperature calculation unit 253b calculates the first refrigerant temperature manipulated variable ΔTf by considering the constraints (the critical minimum temperature Tf ｍｉｎ and the maximum temperature Tf of the second refrigerant ｍａｘ ) is taken into consideration, the first refrigerant temperature manipulated variable ΔTf can be calculated under the constraint conditions.

[0073]

[0074]

[0075]

[0076] Next, the first refrigerant temperature calculation unit 253b calculates the optimum temperature Tf of the first refrigerant. ｔａｒ is the critical minimum temperature Tf of the first refrigerant ｍｉｎ In step S410, it is determined whether the optimum temperature Tf of the first refrigerant is equal to or lower than the optimum temperature Tf ｔａｒ is the critical minimum temperature Tf of the first refrigerant ｍｉｎ If it is determined that the value is not equal to or greater than the predetermined value (NO in S410), the control unit 250 proceeds to step S414.

[0077] In step S410, the optimum temperature Tf of the first refrigerant is determined. ｔａｒ is the critical minimum temperature Tf of the first refrigerant ｍｉｎ When it is determined that the first refrigerant temperature is equal to or less than the input vector u calculated in step 403 and the state quantity x estimated in step 404, the first refrigerant temperature calculation unit 253b outputs a most positive value determination flag to the heat generation amount calculation unit 253c. ｋ Using this, future time N ２ The temperature e2 of each part of the motor 101 at this time is predicted (S411).

[0078] For example, the time it takes for changes in the temperature of the first refrigerant, the flow rate of the first refrigerant, and the temperature of the second refrigerant to affect the temperature changes of each part of the motor 101 is longer than the time it takes for the amount of current supplied to the motor 101 to affect the temperature changes of each part. Therefore, it is necessary to determine the predicted time taking into account the difference between the two times.

[0079] The operation amount of the first refrigerant pump 108 and the like for controlling the cooling circuit is １ On the other hand, the torque limit value of the motor 101 is determined based on the state quantity x at time N ２ Therefore, the state x at time N １ The time required to reach time N ２ This makes it possible to effectively suppress unnecessary torque limitation.

[0080] Next, the heat generation amount calculation unit 253c calculates the heat generation amount at time N ２ The optimum heat generation amount Δu is calculated based on the difference between the predicted temperature of each part of the motor 101 at time N and the target temperature r (S412). ２ The predicted temperature of takes into consideration the heat transfer coefficient manipulated variable Δh calculated in step S406.

[0081] The heat transfer coefficient manipulated variable Δh can be calculated by solving a quadratic programming problem, as shown in the following equations (23) to (28). In this case, the first refrigerant temperature calculation unit 253b can calculate the optimal heat generation amount Δu under the constraint condition by taking into account the constraint condition (Δu≦0).

[0082]

[0083]

[0084]

[0085] Next, the torque control instruction unit 254c refers to the heat value map and calculates the limit torque taking into account the upper limit temperature of the motor 101 based on the rotation speed of the motor 101, the torque of the motor 101, and the frequency of the inverter 110 (S413).

[0086] After the process of step S413 or if the determination in step S410 is NO, second cooling amount control instructing unit 254b calculates the rotation speed of radiator fan 114 and the rotation speed of second refrigerant pump 111 based on the first refrigerant temperature manipulated variable ΔTf, the temperature of the second refrigerant, and the temperature of the first refrigerant (S414). Then, second cooling amount control instructing unit 254b controls the drive of radiator fan 114 and second refrigerant pump 111 according to the determination result.

[0087] After the process of step S414, or if the determination in step S407 is NO, the first refrigerant flow rate calculation unit 253d calculates a target flow rate of the first refrigerant based on the heat transfer coefficient manipulated variable Δh (S415).

[0088] Fig. 5 is a diagram showing the relationship between the heat transfer coefficient and the flow rate of the first refrigerant when the temperature of the first refrigerant changes. The first refrigerant flow rate calculation unit 253d has a memory unit that stores data (maps or tables) that define the relationship between the flow rate of the first refrigerant and the heat transfer coefficient as shown in Fig. 5. The first refrigerant flow rate calculation unit 253d refers to the data that defines the relationship shown in Fig. 5 and calculates the target flow rate of the first refrigerant based on the sum of the heat transfer coefficient manipulated variable Δh and the current heat transfer coefficient h.

[0089] Next, the first cooling amount control instructing unit 254a determines the rotation speed of the first refrigerant pump 108 based on the difference between the actual flow rate and the target flow rate of the first refrigerant. Then, the first cooling amount control instructing unit 254a controls the drive of the first refrigerant pump 108 according to the determined rotation speed of the first refrigerant pump 108.

[0090] In this embodiment, control instructions based on the future temperature are sequentially output, such as the flow rate of the first cooling circuit, the flow rate of the second cooling circuit and the rotation speed of the radiator fan 114, and the torque instruction amount to the inverter 110. This allows the control of the cooling circuits and the torque control of the motor 101 to function in coordination. As a result, unnecessary torque restrictions in the torque control of the motor 101 can be suppressed.

[0091] [Comparison of this embodiment with the prior art] Next, this embodiment will be compared with the prior art using Figures 6 and 7. Figure 6 shows time history temperature results comparing the torque and temperature of the motor of this embodiment with that of the prior art. Figure 7 shows time history results comparing the torque and temperature of the motor, and the flow rate and temperature of the cooling circuit of this embodiment with that of the prior art.

[0092] The vertical axis of Figure 6 represents motor torque and temperature. The horizontal axis of Figure 6 represents time. As shown in Figure 6, in the prior art, when the motor temperature reaches the protection start temperature T1, control is performed to gradually reduce the motor torque. As a result, torque is limited from a period when it is not yet necessary to limit the torque, resulting in unnecessary torque limitation.

[0093] In contrast, in this embodiment, the future temperature of the motor is predicted, and control is performed to reduce torque before the motor temperature exceeds the protection start temperature T1 and reaches the limit temperature T2. Therefore, even if the motor temperature exceeds the protection start temperature T1, torque does not need to be limited immediately. This makes it possible to prevent unnecessary torque limitation. The limit temperature T2 corresponds to the upper limit target temperature according to the present invention. The limit temperature T2 is set to be equal to or lower than the rated temperature of each part of the motor 101.

[0094] The vertical axis of Figure 7 represents the motor torque and temperature and the cooling circuit flow rate and temperature. The horizontal axis of Figure 7 represents time. In the prior art, when the motor temperature reaches the protection start temperature T1, torque limitation and cooling circuit control are initiated simultaneously. Therefore, the cooling circuit control and motor torque control do not function in coordination, resulting in unnecessary torque limitation.

[0095] In contrast, in this embodiment, the future temperature of the motor is predicted. If a rise in the motor temperature is predicted, first, control is performed to increase the flow rate of the refrigerant in the cooling circuit (control of the refrigerant pump). Next, control is performed to lower the temperature of the refrigerant in the cooling circuit (control of the radiator fan). Finally, control is performed to limit the torque of the motor (control of the inverter).

[0096] In this embodiment, the cooling circuit control and the motor torque control function in coordination. As a result, the torque limiting period in this embodiment is shorter than the torque limiting period in the prior art. As a result, the control unit 250 can suppress unnecessary torque limiting.

[0097] 7, the cooling amount control instruction units 254a and 254b control the cooling circuit so that the temperatures of the various parts of the motor 101 are equal to or lower than the cooling circuit target temperature. In other words, the cooling circuit target temperature is a reference temperature for determining whether or not to maximize the cooling capacity of the cooling circuit. The cooling circuit target temperature corresponds to the reference temperature according to the present invention.

[0098] The torque control instruction unit 254c controls the torque of the motor 101 so that the temperature of each part of the motor 101 is equal to or lower than a limit temperature T2 (upper limit target temperature). The limit temperature T2 is set to a value higher than the cooling circuit target temperature described above. Therefore, the control unit 250 starts torque control of the motor 101 after maximizing the cooling capacity of the cooling circuit. This allows the control unit 250 to suppress unnecessary torque restrictions.

[0099] Furthermore, when the target flow rate of the first refrigerant is equal to or greater than the limit flow rate, the torque control instructing unit 254c may execute control to lower the limit temperature T2 (upper limit target temperature), thereby shortening the period during which the torque of the motor 101 is limited.

[0100] The limit temperature T2 and the cooling circuit target temperature are set for each part of the motor 101. This makes it possible to predict the future temperature of each part of the motor 101 and control the cooling circuit and limit the torque. As a result, the cooling circuit can be controlled and the torque can be limited with higher accuracy so that the motor 101 remains at or below the rated temperature.

[0101] Each part of the motor 101 includes at least a stator part and a rotor part. The temperature limit T2 of the stator part is set to be equal to or lower than the dielectric breakdown temperature of the stator coil. If the motor 101 is a permanent magnet synchronous motor, the temperature of the rotor part is the temperature of the magnet. If the motor 101 is a wound field motor, the temperature of the rotor part is the temperature of the rotor field winding.

[0102] Furthermore, this embodiment can prevent the temperature of the stator coil 206 from exceeding the allowable value, which would destroy the insulating coating and cause an electrical short circuit. Furthermore, this embodiment does not restrict the required torque more than necessary to protect the stator coil 206. This prevents the motor 101 from losing the opportunity to output the characteristics it is capable of demonstrating. As a result, the motor 101 functions effectively, enabling the vehicle 100 to perform its intended functions.

[0103] Furthermore, according to this embodiment, it is possible to predict the temperature of each part of the motor 101 individually, and to issue control instructions for the flow rate of the first cooling circuit, the flow rate of the second cooling circuit and the fan rotation speed, and the torque instruction amount to the inverter 110, depending on the state of each part. This makes it possible to prevent the predicted temperature value of the magnet 208 from exceeding the allowable value and causing irreversible demagnetization.

[0104] The above describes the embodiments of the vehicle control device of the present invention, including their effects. However, the vehicle control device of the present invention is not limited to the above embodiments, and various modifications can be made without departing from the spirit of the invention as set forth in the claims.

[0105] Furthermore, the above-described embodiments have been described in detail to clearly explain the present invention, and are not necessarily limited to those including all of the described configurations. Furthermore, it is possible to replace part of the configuration of one embodiment with the configuration of another embodiment, and it is also possible to add the configuration of another embodiment to the configuration of one embodiment. Furthermore, it is possible to add, delete, or replace part of the configuration of each embodiment with another configuration.

[0106] In this specification, the words "parallel" and "orthogonal" are used, but these do not mean only "parallel" and "orthogonal" in the strict sense, but also include "parallel" and "orthogonal" and may also mean a "substantially parallel" or "substantially orthogonal" state within a range in which the functions can be exerted.

[0107] REFERENCE SIGNS LIST 100...vehicle, 101...motor, 102...transmission, 103...differential gear, 104...drive shaft, 105...wheel, 106...first piping, 107...heat exchanger, 108...first refrigerant pump, 109...battery, 110...inverter, 111...second refrigerant pump, 112...radiator, 113...second piping, 114...radiator fan, 115...third refrigerant pump, 116...third piping, 118...first refrigerant tank, 119...second refrigerant tank, 201...housing, 202...stator, 203...rotor, 204...shaft, 205...stator core, 206...stator coil, 207...rotor core, 208...magnet, 250...control unit, 251...state estimation unit, 252...State prediction unit, 252a...First state prediction unit, 252b...Second state prediction unit, 253...Calculation unit, 253a...Heat transfer coefficient calculation unit, 253b...First refrigerant temperature calculation unit, 253c...Heat generation amount calculation unit, 253d...First refrigerant flow rate calculation unit, 254...Control instruction unit, 254a...First cooling amount control instruction unit, 254b...Second cooling amount control instruction unit, 254c...Torque control instruction unit

Claims

1. A vehicle control device comprising: a state estimation unit that acquires operating state information including parameters related to the temperature of a motor and estimates a current state quantity of the motor based on the operating state information; a state prediction unit that predicts a future state quantity of the motor based on the operating state information and the current state quantity; a cooling quantity control instruction unit that controls a cooling circuit for cooling the motor based on the future state quantity; and a torque control instruction unit that controls the torque of the motor based on the future state quantity, wherein the state prediction unit shortens the future period when predicting the future state quantity to be output to the torque control instruction unit compared to the future period when predicting the future state quantity to be output to the cooling quantity control instruction unit.

2. A vehicle control device as described in claim 1, wherein the cooling circuit has piping for circulating a cooling medium for cooling the motor, a refrigerant pump for pressurizing the cooling medium, and a cooling unit for cooling the cooling medium, and further comprises a calculation unit for calculating a target flow rate of the cooling medium based on the future state quantity and a target temperature of the cooling medium based on the future state quantity.

3. A vehicle control device as described in claim 2, wherein the cooling amount control instruction unit controls the operation of the refrigerant pump in accordance with the target flow rate when the target flow rate is smaller than the limit flow rate of the cooling medium, and controls the operation of the cooling unit in accordance with the target temperature when the target flow rate is equal to or greater than the limit flow rate of the cooling medium.

4. The vehicle control device according to claim 3, wherein the torque control instruction unit initiates control to limit the torque of the motor when the target temperature is equal to or lower than the minimum limit temperature of the cooling medium.

5. A vehicle control device as described in claim 3, wherein the cooling unit is capable of varying the amount of outside air ventilated to cool the refrigerant, and when the target flow rate is equal to or greater than the limit flow rate of the cooling medium, the cooling amount control instruction unit executes control to increase the amount of outside air ventilated to the cooling unit.

6. A vehicle control device as described in claim 2, wherein the torque control instruction unit has an upper limit target temperature for controlling the temperature of the motor to be equal to or lower than a predetermined rated temperature, and the cooling amount control instruction unit has a reference temperature that is used to determine whether or not to maximize the cooling capacity of the cooling circuit, and the upper limit target temperature is set higher than the reference temperature.

7. The vehicle control device according to claim 6, wherein the torque control instruction unit executes control to lower the upper limit target temperature when the target flow rate is equal to or greater than the limit flow rate of the cooling medium.

8. The vehicle control device according to claim 6, wherein the upper limit target temperature and the reference temperature are set for at least the stator portion and the rotor portion of the motor, respectively.

9. A vehicle control device as described in claim 2, wherein the calculation unit calculates a target motor temperature that is a target for adjusting the temperature of the motor, a required heat transfer coefficient between the motor and the cooling medium that is required when adjusting the temperature of the motor, and an actual heat transfer coefficient based on the flow rate of the cooling medium and the actual temperature of the cooling medium, and calculates the target flow rate based on the required heat transfer coefficient and the actual heat transfer coefficient.

10. A vehicle control device according to claim 2, wherein the operating state information includes at least one parameter selected from the actual temperature of the motor, the rotational speed of the motor, the shaft torque output by the motor, the amount of electricity supplied to the motor, the actual temperature of the cooling medium, the actual flow rate of the cooling medium, or the outside air temperature.

11. A vehicle control method, in which a state estimation unit acquires driving state information including parameters related to the temperature of the motor, and estimates a current state quantity of the motor based on the driving state information; a state prediction unit predicts a future state quantity of the motor based on the driving state information and the current state quantity; a cooling amount control instruction unit controls a cooling circuit for cooling the motor based on the future state quantity; a torque control instruction unit controls the torque of the motor based on the future state quantity; and the state prediction unit shortens a future period when predicting the future state quantity to be output to the torque control instruction unit than a future period when predicting the future state quantity to be output to the cooling amount control instruction unit.

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