Control apparatus

Abstract

To limit power to be output from a motor at a more appropriate timing.SOLUTION: A control apparatus is used for a motor device including a motor, an inverter that drives the motor, a cooling device that cools the inverter with a cooling medium, and a current sensor attached to a connection line connecting the motor with the inverter. The control apparatus controls the inverter. The control apparatus derives an estimated temperature as an estimated value of the temperature of the current sensor on the basis of a coil temperature as a temperature of a coil of the motor and a coolant temperature as a temperature of the cooling medium and limits power to be output from the motor on the basis of the estimated temperature.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present disclosure relates to a control device.

Background Art

[0002] Conventionally, as this type of control device, a motor device including a motor, an inverter that drives the motor, a cooling device (cooler) that cools the inverter using a cooling medium, and a current sensor attached to a connection line that connects the motor and the inverter has been proposed for controlling the inverter (see, for example, Patent Document 1). In this device, based on the refrigerant temperature as the temperature of the cooling medium, an estimated temperature as an estimated value of the temperature of the electric sensor is specified, and the power output from the motor is limited based on the estimated temperature. Thereby, the current sensor is protected from heat.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the above control device, in recent years, in order to reduce the size of the current sensor, it has been proposed to reduce the area of the connection line. When the area of the connection line becomes smaller, the current sensor receives more heat from the connection line, the estimated temperature and the actual temperature of the current sensor deviate, and there is a concern about excessive temperature rise of the current sensor. As a method for suppressing excessive temperature rise of the current sensor, it is conceivable to lower the threshold value of the temperature of the current sensor for determining whether or not to limit the power output from the motor, or to estimate the temperature of the current sensor higher. However, in this method, the frequency of limiting the power output from the motor increases, and the power performance may be impaired. Therefore, it has been recognized as an important issue to limit the power output from the motor at a more appropriate timing.

[0005] The control device of the present disclosure mainly aims to limit the power output from the motor at more appropriate timings.

Means for Solving the Problems

[0006] The control device of the present disclosure has adopted the following means to achieve the above main purpose.

[0007] The control device of the present disclosure is used in a motor device including a motor, an inverter that drives the motor, a cooling device that cools the inverter using a cooling medium, and a current sensor attached to a connection line connecting the motor and the inverter, and is a control device that controls the inverter, derives an estimated temperature as an estimated value of the temperature of the current sensor based on the coil temperature as the temperature of the coil of the motor and the refrigerant temperature as the temperature of the cooling medium, and limits the power output from the motor based on the estimated temperature which is the gist.

[0008] In this control device of the present disclosure, an estimated temperature as an estimated value of the temperature of the current sensor is derived based on the coil temperature as the temperature of the coil of the motor and the refrigerant temperature as the temperature of the cooling medium. Thereby, the estimated temperature can be made closer to the actual temperature of the current sensor. Then, the power output from the motor is limited based on the estimated temperature. Since the power output from the motor is limited based on an estimated temperature closer to the actual temperature of the current sensor, the power output from the motor can be limited at more appropriate timings.

[0009] In such a control device of the present disclosure, an arrival temperature as the temperature that the current sensor reaches may be estimated based on the coil temperature and the refrigerant temperature, and the estimated temperature may be calculated by performing a first-order lag process on the arrival temperature. By doing so, the estimated temperature can be made closer to the actual temperature of the current sensor, and the power output from the motor can be limited at more appropriate timings.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

Embodiments for Carrying Out the Invention

[0011] Embodiments of the present disclosure will be described with reference to the drawings. FIG. 1 is a schematic configuration diagram for explaining the configuration of an electric vehicle 10 equipped with the control device of this embodiment. FIG. 2 is an explanatory diagram for explaining the outline of the configuration around the current sensor 23u. As shown in FIG. 1, the electric vehicle 10 includes a motor 22, an inverter 24, a battery 26 as a power storage device, a cooling device 40, and an electronic control unit 60 as a control device. In the electric vehicle 10, at least the motor 22 and the inverter 24 are housed in the same motor room (vehicle body space).

[0012] The motor 22 is configured as a three-phase AC motor, and includes a rotor in which permanent magnets are embedded in a rotor core, and a stator in which coils of U-phase, V-phase, and W-phase are wound around a stator core respectively. The rotor of the motor 22 is connected to a drive shaft 16 that is connected to drive wheels 12 via a differential gear 14.

[0013] The inverter 24 is used to drive the motor 22 and is connected to the battery 26 via the power line 28. The inverter 24 has six transistors as six switching elements and six diodes. The six transistors are arranged in pairs of two each so as to be on the source side and the sink side with respect to the positive line and the negative line of the power line 28. Each of the connection points of the transistor pairs of the six transistors is connected to each of the three-phase (U-phase, V-phase, W-phase) coils of the motor 22 via busbars 50u, 50v, 50w as connection lines. Therefore, when a voltage is applied to the inverter 24, a rotating magnetic field is formed in the three-phase coils by adjusting the ratio of the on-time of the paired transistors by the electronic control unit 60, and the motor 22 is rotationally driven. Current sensors 23u, 23v, 23w are attached to the busbars 50u, 50v, 50w. As shown in FIG. 2, the current sensor 23u includes a magnetic core 230u, a Hall IC 232u installed on the magnetic core 230u, and a resin mold 234u that seals the magnetic core 230u and the Hall IC 232u. The current sensor 23u measures the current value of the busbar 50u by measuring the magnetic field generated in the magnetic core 230u by the current flowing through the busbar 50u. Since the current sensors 23v, 23w have the same configuration as the current sensor 23u, their description is omitted.

[0014] The battery 26 is configured as a secondary battery such as a lithium-ion secondary battery. The battery 26 is connected to the inverter 24 via the power line 28 as described above.

[0015] The cooling device 40 includes a circulation flow path 42, a heat exchanger 44, an electric pump 46, and a cooler 47. The cooler 47 is attached to the inverter 24 to exchange heat with the inverter 24 and cool the inverter 24. The circulation flow path 42 is configured as a flow path for circulating a cooling medium in this order through the motor 22, the cooler 47, the battery 26, and the heat exchanger 44. The electric pump 46 circulates the cooling medium in the circulation flow path 42. Note that the circulation flow path 42 may be configured such that the cooling medium circulates in the order of the cooler 47, the motor 22, the battery 26, and the heat exchanger 44, or may be configured such that the cooling medium circulates in the order of the battery 26, the motor 22, the cooler 47, and the heat exchanger 44.

[0016] The electronic control unit 60 includes a microcomputer, and the microcomputer has a CPU, a ROM, a RAM, a flash memory, an input / output port, and a communication port. The electronic control unit 60 inputs signals from various sensors. For example, the electronic control unit 60 inputs the rotational position θm of the rotor of the motor 22 from a rotational position sensor (not shown), the phase currents Iu, Iv, Iw of the U-phase, V-phase, and W-phase of the motor 22 from the current sensors 23u, 23v, 23w, the coil temperatures αcu, αcv, αcw detected by temperature sensors 51u, 51v, 51w (only the temperature sensor 51u is shown in FIG. 2) for detecting the temperatures of the motor busbars 22u, 22v, 22w (only the motor busbar 22u is shown in FIG. 2) connected to the busbars 50u, 50v, 50w and the three-phase coils of the motor 22, and the refrigerant temperature αw as the temperature sensor 47a for detecting the temperature of the cooling medium passing through the cooler 47.

[0017] The electronic control unit 60 outputs various control signals. For example, the electronic control unit 60 outputs a control signal to the inverter 24 and a control signal to the electric pump 46. The electronic control unit 60 calculates the electrical angle θe and the rotational speed Nm of the motor 22 based on the rotational position θm of the rotor of the motor 22. The electronic control unit 60 calculates the state of charge SOC of the battery 26 based on the integrated value of the current Ib of the battery 26.

[0018] In the electric vehicle 10 of the embodiment configured in this way, the electronic control unit 60 sets the required torque Td* required for the drive shaft 16 based on the accelerator opening Acc as the opening of the accelerator pedal and the vehicle speed V, sets the torque command Tm* of the motor 22 so that the set required torque Td* is output to the drive shaft 16, and performs switching control of each transistor of the inverter 24 so that the motor 22 is driven by the torque command Tm*. Hereinafter, the control of such a motor 22 (inverter 24) is referred to as "normal control".

[0019] Next, the operation of the electric vehicle 10 of the embodiment configured in this way, particularly the operation when suppressing excessive temperature rise of the current sensor 23u, will be described. FIG. 3 is a flowchart showing an example of a control routine executed by the electronic control unit 60. This routine is repeatedly executed every predetermined time titr (for example, several msec) during the period from when the electric vehicle 10 is system-started to when it is system-stopped. The temperature and the like input or set in this control routine are reset to the value 0 or a predetermined value when the electric vehicle 10 is system-stopped. In the embodiment, the operation when suppressing excessive temperature rise of the current sensor 23u will be described, but excessive temperature rise can also be suppressed for the current sensors 23v and 23w by the same operation.

[0020] When this routine is executed, the CPU of the electronic control unit 60 executes a process of inputting the coil temperature αcu, the refrigerant temperature αw, the current temperature αcn, and the previous temperature αcp (S100). The coil temperature αcu is input as the value detected by the temperature sensor 51u. The refrigerant temperature αw is input as the value detected by the temperature sensor 47a. The current temperature αcn is the estimated temperature αcest after the lapse of a predetermined time titr calculated in S120 described later when the previous execution of this routine was performed, that is, the estimated value of the current temperature of the current sensor 23u. The previous temperature αcp is the estimated temperature αcest after the lapse of a predetermined time titr calculated in S120 described later when the routine was executed the time before last, that is, the estimated value of the previous temperature of the current sensor 23u. When the electric vehicle 10 is system-started and this routine is executed for the first time, the current temperature αcn and the previous temperature αcp are not set. In this case, the reaching temperature αcr set in S110 described later may be used as the current temperature αcn and the previous temperature αcp.

[0021] Next, based on the coil temperature αcu and the refrigerant temperature αw, the reaching temperature αcr as the temperature of the current sensor 23u is estimated when there is no delay in the change in the temperature of the current sensor 23u with respect to the change in the temperature of the coil of the motor 22 and the change in the temperature of the cooling medium after passing through the cooler 47 (S110). The reaching temperature αcr is estimated to be higher when the coil temperature αcu is high than when it is low, and higher when the refrigerant temperature αw is high than when it is low. The reason for making the reaching temperature αcr higher when the coil temperature αcu is high than when it is low is based on the fact that when the coil temperature αcu increases, the current sensor 23u is likely to receive heat from the coil of the motor 22 via the bus bar 50u and its temperature rises. Also, the reason for making the reaching temperature αcr higher when the refrigerant temperature αw is high than when it is low is based on the fact that when the refrigerant temperature αw is high, the cooling performance of the cooling device 40 deteriorates and the current sensor 23u is likely to have its temperature rise.

[0022] Then, a first-order lag process is applied to the reaching temperature αcr using the following equation (1) to calculate an estimated temperature αcest as an estimated value of the temperature of the current sensor 23u after a predetermined time titr (S120). In Equation (1), “τ” is a value determined in advance by experiments, analysis, machine learning, etc. as the time constant of the temperature change of the current sensor 23u with respect to the temperature change of the coil of the motor 22 and the temperature change of the cooling medium after passing through the cooler 47. The temperature change of the current sensor 23u changes with a certain delay with respect to the temperature change of the coil of the motor 22 and the temperature change of the cooling medium after passing through the cooler 47. Therefore, by applying a first-order lag process to the reaching temperature αcr and calculating the estimated temperature αcest as an estimated value of the temperature of the current sensor 23u after a predetermined time titr, the estimated temperature αcest can be made closer to the actual temperature of the current sensor 23u after a predetermined time titr.

[0023] αcest = αcp+(αcr - αcn)·(1 - exp(-τ / titr)) ···(1)

[0024] Next, it is determined whether or not the estimated temperature αcest is equal to or higher than a threshold value αth (S130). The threshold value αth is a value determined in advance by experiments, analysis, machine learning, etc. as the threshold value of the temperature of the current sensor 23u at which it can be determined that the output from the motor 22 should be restricted. Therefore, S130 is a process for determining whether or not the output from the motor 22 should be restricted.

[0025] When the estimated temperature αcest is less than the threshold value αth in S130, the above-described normal control is executed (S140), and this routine is terminated. When the estimated temperature αcest is equal to or greater than the threshold value αth in S130, output limit control for limiting the output from the motor 22 is executed (S150). This routine is terminated. In the output limit control, the required torque Td* required for the drive shaft 16 based on the accelerator opening Acc as the opening of the accelerator pedal and the vehicle speed V is set to be smaller than the required torque Td* set at the same accelerator opening Acc and vehicle speed V in the above-described normal control, and the torque command Tm* of the motor 22 is set so that the set required torque Td* is output to the drive shaft 16, and switching control of each transistor of the inverter 24 is performed so that the motor 22 is driven by the torque command Tm*. By executing the output limit control, the temperature rise of the motor 22 is suppressed, and the amount of heat received by the bus bar 50u is reduced, so that the temperature rise of the current sensor 23u can be suppressed, and the current sensor 23u can be protected. Further, since the output limit control is executed based on the estimated temperature αcest that is closer to the actual temperature of the current sensor 23u, the power output from the motor 22 can be limited at a more appropriate timing.

[0026] According to the electric vehicle 10 equipped with the control device of the present embodiment described above, based on the coil temperature αcu as the temperature of the coil of the motor 22 and the refrigerant temperature αw as the temperature of the cooling medium, the estimated temperature αcest as the estimated value of the temperature of the current sensor 23u is derived, and the power output from the motor 22 is limited based on the estimated temperature αcest, so that the power output from the motor 22 can be limited at a more appropriate timing.

[0027] Further, the reaching temperature αcr as the temperature that the current sensor 23u reaches is estimated based on the coil temperature αcu and the refrigerant temperature αw, and the estimated temperature αcest is calculated by performing a first-order lag process on the reaching temperature αcr, so that the power output from the motor 22 can be limited at a more appropriate timing.

[0028] In the above-described embodiment, an estimated temperature αcest obtained by subjecting the reached temperature αcr to a first-order lag process is calculated, and when the estimated temperature αcest is equal to or higher than the threshold value αth, output limit control is executed. However, when the temperature change of the current sensor 23u can sufficiently quickly follow the temperature change of the coil of the motor 22 and the temperature change of the cooling medium after passing through the cooler 47, the reached temperature αcr may be set to the estimated temperature αcest, and output limit control may be executed when the estimated temperature αcest is equal to or higher than the threshold value αth.

[0029] In the above-described embodiment, in the output limit control, the required torque Td* is set to be smaller than the above-described normal control, thereby restricting the power output from the motor 22. However, the normal control may be used to set the torque command Tm* in a similar manner, and the motor 22 may be driven with the torque obtained by restricting the torque command Tm* by the upper limit torque Tmax. The upper limit torque Tmax may be a value determined in advance by experiments, analysis, machine learning, etc. as the upper limit value of the output torque of the motor 22 at which the current sensor 23u overheats.

[0030] In the above-described embodiment, the control device of the present disclosure is applied to the electric vehicle 10. However, the control device of the present disclosure may be applied to a hybrid vehicle that can travel by power from an engine and power from a motor. Further, the control device of the present disclosure is not limited to being applied to an automobile, and can be applied to any form as long as it is a motor device including a motor 22, an inverter 24, a cooling device 40, and a current sensor 23u.

[0031] The correspondence between the main elements of the embodiment and the main elements of the invention described in the section of means for solving the problems will be described. In the embodiment, the motor 22 corresponds to the "motor", the inverter 24 corresponds to the "inverter", the cooling device 40 corresponds to the "cooling device", the current sensor 23u corresponds to the "current sensor", and the electronic control unit 60 corresponds to the "control device".

[0032] Note that the correspondence between the main elements of the embodiments and the main elements of the invention described in the section of means for solving the problems is an example for specifically explaining the mode for carrying out the invention described in the section of means for solving the problems in the embodiments. Therefore, it does not limit the elements of the invention described in the section of means for solving the problems. That is, the interpretation of the invention described in the section of means for solving the problems should be made based on the description in that section, and the embodiments are merely specific examples of the invention described in the section of means for solving the problems.

[0033] As described above, the embodiments for carrying out the present disclosure have been explained. However, the present disclosure is not limited to such embodiments, and it goes without saying that it can be implemented in various forms without departing from the gist of the present disclosure.

Industrial Applicability

[0034] The present disclosure can be used in the manufacturing industry of control devices and the like.

Explanation of Reference Numerals

[0035] 10 Electric vehicle, 12 Driving wheels, 14 Differential gear, 16 Drive shaft, 22 Motor, 22u, 22v, 22w Motor bus bar, 23u, 22v, 22w Current sensor, 24 Inverter, 26 Battery, 28 Power line, 40 Cooling device, 42 Circulation flow path, 44 Heat exchanger, 46 Electric pump, 47 Cooler, 47a, 51u, 51v, 51w Temperature sensor, 50u, 50v, 50w Bus bar, 60 Electronic control unit, 230u Magnetic core, 232u Hall IC, 234u Resin mold.

Claims

1. A control device used in a motor device comprising a motor, an inverter that drives the motor, a cooling device that cools the inverter using a cooling medium, and a current sensor attached to a connection line connecting the motor and the inverter, the control device being configured to: Derive an estimated temperature as an estimated value of the temperature of the current sensor based on the coil temperature as the temperature of the coil of the motor and the refrigerant temperature as the temperature of the cooling medium, and limit the power output from the motor based on the estimated temperature Control device.

2. The control device according to claim 1, wherein: An arrival temperature as the temperature that the current sensor reaches is estimated based on the coil temperature and the refrigerant temperature, and the estimated temperature is calculated by subjecting the arrival temperature to a first-order lag process Control device.

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