Control device for mobile object, storage medium, and program

Abstract

To provide technique for increasing maximum motor torque, thereby improving the acceleration performance of a mobile object.SOLUTION: A vehicle MV which is a mobile object, comprises: a cooling mechanism which cools an inverter 30 by cooling water; and a cooling water temperature sensor 53 which detects the temperature of the cooling water flowing to the inverter 30. A controller 80 controls the output current of the inverter 30. The maximum output current Imax of the inverter 30 is set according to the cooling water temperature Tc. A negative correlation including at least one inflection point is set between the maximum output current Imax and the cooling water temperature Tc. The rate of change of the maximum output current Imax with respect to the cooling water temperature Tc is smaller in a first cooling water temperature region W1 below the inflection point temperature than in a second cooling water temperature region W2 above the inflection point temperature. This prevents the occurrence of thermal runaway, while also enabling the inverter's maximum output power to be fully utilized and the motor torque to be increased.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The disclosure in this specification relates to technology that can be used for a control device, a control method, a storage medium, and a program for a mobile object. [Background technology]

[0002] As an example of this type of control device, a method for operating an electric vehicle including a rechargeable battery, a direct current (DC) bus, an electric motor, and a power inverter electrically connecting the rechargeable battery and the electric motor is known, as described in Patent Document 1. In this method, a vehicle controller identifies an operating mode of the electric vehicle and / or the power inverter, and establishes calibration settings corresponding to the operating mode. The calibration settings include a first coolant temperature threshold, a second coolant temperature threshold higher than the first coolant temperature threshold, and a set of motor calibration torque limits as a function of coolant temperature and a current DC busbar voltage of the DC busbar. The method also determines whether the current coolant temperature of the coolant in the power inverter is greater than or equal to the first coolant temperature threshold and less than or equal to the second coolant temperature threshold. In response to the current coolant temperature being greater than or equal to the first coolant temperature threshold and less than or equal to the second coolant temperature threshold, the motor torque limit of the electric motor is set to a first torque limit value selected from a first fixed torque limit range within the motor calibration torque limits between the first and second coolant temperature thresholds. A command signal is then sent by the vehicle controller to the power inverter to adjust the power transfer between the rechargeable battery and the electric motor based on the motor torque limits of the electric motor.

[0003] This patent document shows that the equipment can be protected from being affected when the temperature is higher or lower than a certain refrigerant temperature, but the maximum output power cannot be obtained in other areas, so there is still room for further improvement. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] CN114475270A Summary of the Invention

[0005] The disclosure in this specification has been made in consideration of the above technical problems. The disclosure in this specification aims to provide a control technology for a moving body that can improve the acceleration performance of the moving body. This aim may be achieved by providing a control device for a moving body, a control method for a moving body, a program for causing a computer to execute the control method for a moving body, and a storage medium on which the program is recorded.

[0006] The technology disclosed in this specification increases the maximum motor torque by changing the maximum output current that the inverter can output based on the cooling medium temperature of the cooling mechanism that cools the inverter that controls the rotating electric machine that generates the power to move the moving body.

[0007] One aspect of the disclosure in this specification relates to a control device for a mobile object. The control device is applied to the mobile object. The mobile object includes: a rotating electric machine having a rotor and a stator with a stator winding including a plurality of phase windings; a power storage unit; an inverter having a series connection of upper and lower arm switches, which converts DC power supplied from the power storage unit into AC power by switching control and supplies the AC power to the rotating electric machine; a cooling mechanism which cools the inverter with a cooling medium; a cooling medium temperature sensor which detects the temperature of the cooling medium flowing through the inverter; and a control device which controls the inverter output current. The control device controls the inverter so as to establish a negative correlation between the inverter's maximum output current Imax and the cooling medium temperature Tc. The control device also establishes at least one inflection point in the negative correlation. The inflection point includes a first inflection point P1. The negative correlation established by the control device is characterized by a rate of change of the inverter's maximum output current with respect to the cooling medium temperature. The negative correlation provided by the control device is characterized by a first coolant temperature region W1 below the first inflection point and a second coolant temperature region W2 above the first inflection point. The negative correlation provided by the control device is characterized by setting the rate of change in the first coolant temperature region W1 to be smaller than the rate of change in the second coolant temperature region W2. In other words, the control device is configured so that the rate of change of the inverter's maximum output current with respect to the coolant temperature is smaller in the first coolant temperature region W1 than in the second coolant temperature region W2. In other words, the control device is configured so that the rate of change of the inverter's maximum output current with respect to the coolant temperature is smaller in the first coolant temperature region W1 than in the second coolant temperature region W2.

[0008] In this disclosure, a control device for a mobile object establishes a negative correlation between the maximum output current Imax of the inverter and the cooling medium temperature Tc. Additionally, the negative correlation is characterized by the establishment of at least one inflection point. The negative correlation includes a first inflection point P1 as an inflection point. The control device is configured so that the rate of change of the maximum output current of the inverter with respect to the cooling medium temperature is smaller in a first cooling medium temperature region W1 below the first inflection point than in a second cooling medium temperature region W2 above the first inflection point. As a result, the control device prevents the cooling capacity of the cooling device from being exceeded and thermal runaway from occurring. At the same time, the control device can fully utilize the maximum output power of the inverter to increase the torque of the electric motor.

[0009] The disclosure of this specification provides a program that causes a control device to execute a control process for controlling an inverter's output current. The program includes an acquiring process, a setting process, and a controlling process. The acquiring process acquires a cooling medium temperature (Tc) detected by a cooling medium temperature sensor. The setting process sets the maximum output current (Imax) according to the cooling medium temperature (Tc) based on a negative correlation between the cooling medium temperature (Tc) and the inverter's maximum output current (Imax), the negative correlation having at least one inflection point. Here, the negative correlation indicates that the rate of change of the inverter's maximum output current with respect to the cooling medium temperature is smaller in a temperature range below the inflection point than in a temperature range above the inflection point. As a result, the setting process sets the maximum output current (Imax) according to the cooling medium temperature (Tc) based on the negative correlation. The controlling process controls the inverter's output current based on the maximum output current (Imax).

[0010] The technology disclosed in this specification can be understood and implemented as a control device, a control method, a storage medium, and / or a program.

[0011] The various embodiments disclosed in this specification employ different technical means to achieve their respective objectives. The claims and the reference numerals in parentheses in this section are intended to exemplify the correspondence with the embodiments described below and are not intended to limit the technical scope. The objectives, features, and advantages disclosed in this specification will become more apparent by referring to the following detailed description and the accompanying drawings. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is a diagram showing the overall structure of a drive system according to the first embodiment. [Figure 2] FIG. 2 is a curve diagram showing the relationship between heat generation of the inverter and the coolant temperature. [Figure 3] FIG. 3 is a curve diagram showing the relationship between the coolant temperature and the output torque of the rotating electrical machine. [Figure 4] FIG. 4 is a curve diagram showing the relationship between the maximum output current of the inverter and the coolant temperature in the first embodiment. [Figure 5] FIG. 5 is a flowchart showing inverter control steps executed by the control device in the first embodiment. [Figure 6] FIG. 6 is a curve diagram showing the relationship between the maximum output current of the inverter and the coolant temperature in the first modification of the first embodiment. [Figure 7] FIG. 7 is a flowchart showing inverter control steps executed by the control device in the first modification of the first embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0013] Several embodiments will be described with reference to the drawings. In several embodiments, functionally and / or structurally corresponding and / or associated parts may be designated by the same reference numerals or reference numerals that differ by one hundred or more digits. For corresponding and / or associated parts, reference may be made to the descriptions of other embodiments.

[0014] First embodiment A first embodiment in which the mobile body control technology of the present disclosure is applied to a drive system of an electric vehicle MV as a mobile body will be described below with reference to the drawings. In this embodiment, the mobile body is an electric vehicle MV. The mobile body is not limited to a vehicle as a mobile body on land. The mobile body may be a ship as a mobile body on or in water, or an aircraft as a mobile body in the air. Hereinafter, the electric vehicle MV will be abbreviated as vehicle MV.

[0015] FIG. 1 is an overall configuration diagram of a drive system for a vehicle MV in a first embodiment. As shown in FIG. 1, the vehicle MV includes a rotating electric machine 20. The rotating electric machine 20 is a multi-phase synchronous motor. The rotating electric machine 20 has a rotor and a stator. The rotor includes an excitation winding. The stator has a stator winding including multiple phase windings and a stator core. The rotating electric machine 20 is a three-phase synchronous motor.

[0016] The stator includes a three-phase armature winding. The three-phase armature winding includes a star-connected U-phase winding, a V-phase winding, and a W-phase winding. The phase windings are arranged with an electrical angle offset of 120°. In this embodiment, the number of turns of each phase winding is set to be the same. Therefore, for example, the inductance of each phase winding is set to be the same. The rotor of the rotating electric machine 20 can transmit power to the drive wheels of the vehicle MV.

[0017] The vehicle MV further includes an inverter 30. The inverter 30 converts DC power from the storage battery 40 into AC power and outputs the AC power. The storage battery 40 provides a power storage unit. The rotating electric machine 20 applies drive torque to drive wheels of the vehicle MV based on the AC power output from the inverter 30.

[0018] The inverter 30 includes power devices that are series-connected upper-arm switches QUH, QVH, and QWH and lower-arm switches QUL, QVL, and QWL corresponding to three phases. In this embodiment, voltage-controlled semiconductor switching devices, specifically IGBTs, are used for the switches QUH, QVH, QWH, QUL, QVL, and QWL. Therefore, the high-potential terminal of each switch QUH, QVH, QWH, QUL, QVL, and QWL serves as the collector, and the low-potential terminal serves as the emitter. Diodes DUH, DVH, DWH, DUL, DVL, and DWL, serving as flywheel diodes, are connected in reverse parallel to each switch QUH, QVH, QWH, QUL, QVL, and QWL.

[0019] The collectors of the upper arm switches of each phase are connected to the positive terminal of the storage battery 40 via a positive bus bar Lp. The emitters of the lower arm switches of each phase are connected to the negative terminal of the storage battery 40 via a negative bus bar Ln. The positive bus bar Lp and the negative bus bar Ln are connected via a capacitor 31. The capacitor 31 can be built into the inverter 30 or can be provided externally to the inverter 30.

[0020] Therefore, the inverter 30 has a series-connected assembly of upper arm switches and lower arm switches. The inverter 30 has a number of series-connected assembly corresponding to the number of phases of the rotating electric machine 20. The inverter 30 converts DC power supplied from the storage battery 40 into AC power and supplies it to the rotating electric machine 20 by controlling the switching of the plurality of series-connected assembly.

[0021] The storage battery 40 provides a power storage unit. The power storage unit stores electric power and supplies the electric power to the rotating electric machine 20 via the inverter 30. The storage battery 40 is, for example, a battery pack. The terminal voltage of the storage battery 40 is, for example, several hundred volts. The storage battery 40 is, for example, a secondary battery such as a lithium ion battery or a nickel-metal hydride battery.

[0022] One end of the reactor L is connected to the positive bus bar Lp, and the other end of the reactor L is connected to the negative bus bar Ln.

[0023] The vehicle MV also includes a current sensor 21, a rotation angle sensor 22, and a controller 80. The controller 80 corresponds to a "control device." The current sensor 21 detects the current flowing through the stator windings of at least two of the phases. The rotation angle sensor 22 is, for example, an analyzer, and detects the rotation speed and phase information of the rotating electric machine. The detection values ​​of the sensors 21 and 22 are input to the controller 80, whereby feedback control is performed.

[0024] The controller 80 is primarily composed of a microcomputer including a CPU. The functions provided by the microcomputer can be provided by software recorded in a physical storage device, a computer executing the software, software alone, hardware alone, or a combination thereof. For example, if the microcomputer is provided as an electronic circuit in the form of hardware, the functions can be provided by digital circuits or analog circuits including multiple logic circuits. For example, the microcomputer executes programs stored in a non-transitory tangible storage medium contained within the microcomputer. The programs include, for example, programs for the processes shown in FIG. 5. Executing the programs results in the execution of the methods corresponding to the programs. The storage medium is, for example, a non-volatile memory. Furthermore, the programs stored in the storage medium can be updated via a network such as the Internet.

[0025] The controller 80 can perform power running control. Power running control is switching control of the inverter 30 for converting DC power output from the storage battery 40 into AC power and supplying it to the stator windings of the rotating electric machine 20. When this control is performed, the rotating electric machine 20 acts as an electric motor and generates power running torque. The controller 80 can also perform regenerative drive control. Regenerative drive control is switching control of the inverter 30 for converting AC power generated by the rotating electric machine 20 into DC power and supplying it to the storage battery 40. When this control is performed, the rotating electric machine 20 acts as a generator and generates regenerative torque.

[0026] The controller 80 performs switching control of the inverter 30 by, for example, PWM control at a predetermined switching frequency (carrier frequency), and uses the control amount of the rotary electric machine 20, for example, torque feedback control, as its command value.

[0027] When the controller 80 performs switching control of the inverter 30 using PWM control, the inverter 30 generates heat, which limits the maximum output current of the inverter 30, and thereby limits the motor torque of the rotating electric machine 20, making it impossible to improve the acceleration performance of the vehicle MV.

[0028] For this reason, the vehicle MV also includes a cooling mechanism. By providing the cooling mechanism to cool the inverter 30, it is possible to prevent the temperature of the inverter 30 from rising too high and causing a breakdown.

[0029] The cooling mechanism uses cooling water as a cooling medium. The cooling mechanism includes a circulation path 50 that circulates the cooling water, a cooler 51 as a cooling device, an electric fan 52, and a water pump 54. The cooling water is circulated by supplying power to the water pump 54 to operate it. The cooler 51 cools the cooling water that flows in via the circulation path 50 and supplies it to the water pump 54. The cooling water that flows into the cooler 51 is cooled by the wind blowing into the cooler 51 as the vehicle MV travels and the wind blown into the cooler 51 by rotating the fan 52.

[0030] The cooling water is, for example, an antifreeze liquid or a mixture of antifreeze liquid and water. The antifreeze liquid is, for example, a liquid called LLC. Instead of cooling water, the cooling medium can be provided by a flowable substance capable of transporting heat, such as gas or oil.

[0031] In the circulation path 50, the inverter 30 and the rotating electric machine 20 are arranged in this order downstream of the cooler 51. However, the arrangement order of the rotating electric machine 20 and the inverter 30 in the circulation path 50 is not limited to the above order.

[0032] The vehicle MV further includes a coolant temperature sensor 53. The coolant temperature sensor 53 detects the temperature of the coolant flowing through the inverter 30 in the circulation path 50.

[0033] As a result of research, the inventors of the present application have found that there is a relationship between the heat generation of the inverter 30 and the coolant temperature, as shown in Figure 2. As shown in Figure 2, for the same heat resistance temperature (at maximum output), when the coolant temperature is relatively high, for example, at B°C, the allowable amount of heat generated by the inverter is relatively low. Conversely, when the coolant temperature is relatively low, for example, at A°C, the allowable amount of heat generated by the inverter is relatively high, and in this case, an increase in the maximum output current can be permitted.

[0034] Also, as shown in FIG. 3, at the same DC voltage, when the coolant temperature is relatively low, for example, A°C, the motor torque is higher than when the coolant temperature is relatively high, for example, B°C.

[0035] According to this, the maximum output current Imax of the inverter 30 and the motor torque have a negative correlation with the coolant temperature Tc.

[0036] 4 shows an example of the correlation between the coolant temperature Tc and the maximum output current Imax. The correlation can also be called a negative correlation. At least one inflection point P1 is set in the negative correlation.

[0037] In the disclosure of this specification, the curve of maximum output current Imax versus coolant temperature Tc has at least one first inflection point P1, and the maximum output current Imax of the inverter 30 changes linearly with the temperature before the first inflection point P1. Because the change in maximum output current Imax is linear within a first coolant temperature region W1 that is lower than the first inflection point P1, a map can be drawn by linear interpolation with the coolant temperature Tc on the horizontal axis and the maximum output current Imax on the vertical axis, and this can be easily implemented.

[0038] By setting the coolant temperature Tc at the first inflection point P1 to the heat-resistant critical temperature Tmax of the inverter 30, it is possible to prevent the cooling capacity of the cooling device from being exceeded, thereby preventing thermal runaway.

[0039] In the first coolant temperature region W1, which is lower than the first inflection point P1, the coolant temperature Tc is relatively low compared to the second coolant temperature region W2, which is higher than the first inflection point P1. This causes the maximum output current Imax of the inverter 30 to increase more slowly. Therefore, the rate of change of the maximum output current Imax of the inverter 30 with respect to the coolant temperature Tc, i.e., the first slope S1, is set to a relatively small value. As one example, the first slope S1 is set to 8 Arms / 1°C or less. The set value of this first slope S1 is a reasonable value that takes into consideration the heat generation and cooling capacity of the inverter's power devices.

[0040] By gradually increasing the maximum output current Imax of the inverter 30 in accordance with the decrease in the coolant temperature in the first coolant temperature region W1, which is lower than the first inflection point P1, it is possible to obtain a sufficient maximum output power of the inverter 30 and increase the motor torque.

[0041] On the other hand, in the second coolant temperature region W2 on the higher side of the first inflection point P1, the coolant temperature Tc exceeds the heat-resistant critical temperature Tmax of the inverter 30, compared to the first coolant temperature region W1 on the lower side of the first inflection point P1, and therefore the maximum output current Imax of the inverter 30 needs to be reduced more rapidly. Therefore, the rate of change of the maximum output current Imax of the inverter 30 with respect to the coolant temperature Tc, i.e., the second slope S2, is set to be relatively large.

[0042] By rapidly reducing the maximum output current Imax of the inverter 30 in the second coolant temperature region W2, which is higher than the first inflection point P1, when the coolant temperature Tc exceeds the heat-resistant critical temperature Tmax of the inverter 30, the maximum output power of the inverter 30 can be rapidly reduced to prevent the cooling capacity of the cooling device from being exceeded and thermal runaway from occurring.

[0043] The above setting prevents the cooling capacity of the cooling device from being exceeded, and prevents the occurrence of thermal runaway, while at the same time making it possible to obtain a sufficient maximum output power of the inverter 30 and increase the torque of the electric motor.

[0044] The inverter control executed by the controller 80 will be described below with reference to FIG.

[0045] FIG. 5 is a flowchart showing inverter control steps executed by the control device in the first embodiment.

[0046] In step S11, the temperature of the coolant flowing through the inverter 30 detected by the coolant temperature sensor 53, that is, the coolant temperature Tc, is acquired (corresponding to a coolant temperature acquisition unit).

[0047] Thereafter, in step S12, it is determined whether or not the coolant temperature Tc acquired in step S11 exceeds the heat-resistant critical temperature Tmax of the inverter 30 (corresponding to a first determination unit).

[0048] If the determination result in step S12 is negative, that is, if the coolant temperature Tc is equal to or lower than the heat-resistant critical temperature Tmax of the inverter 30, then in step S13, the controller 80 increases the maximum output current Imax of the inverter 30 at a first gradient S1 as the coolant temperature Tc decreases. If the determination result in step S12 is positive, then in step S14, the controller 80 decreases the maximum output current Imax of the inverter 30 at a second gradient S2 as the coolant temperature Tc increases, where the second gradient S2 is greater than the first gradient S1. The processes in steps S13 and S14 correspond to the operation unit.

[0049] The inverter control executed by the controller 80 described above is repeatedly executed at predetermined time intervals.

[0050] As described above, in this embodiment, the controller 80 is configured to control the output current of the inverter 30, i.e., the current supplied to the rotating electric machine 20. The controller 80 is configured to control the maximum output current Imax of the inverter 30 in response to the coolant temperature Tc so that the maximum output current Imax has a negative correlation with the coolant temperature Tc. Furthermore, the controller 80 is configured so that the negative correlation, which is a control characteristic, has at least one inflection point. The controller 80 is configured so that at least one inflection point in the negative correlation has a first inflection point P1. As a result, the negative correlation has a first coolant temperature region W1 lower than the first inflection point P1 and a second coolant temperature region W2 higher than the first inflection point P1. Note that the first inflection point P1 may belong to either the first coolant temperature region W1 or the second coolant temperature region W2. Therefore, the first coolant temperature region W1 may be referred to as a region equal to or lower than the temperature of the first inflection point P1, or a region lower than the temperature of the first inflection point P1. Furthermore, the second coolant temperature region W2 may be referred to as a region exceeding the temperature of the first inflection point P1, or a region equal to or higher than the temperature of the first inflection point P1.

[0051] The negative correlation is set so that the rate of change of the inverter's maximum output current Imax relative to a change in the coolant temperature Tc is different between the first coolant temperature region W1 and the second coolant temperature region W2. The rate of change in the first coolant temperature region W1 is set smaller than the rate of change in the second coolant temperature region W2. Therefore, the negative correlation realized by the controller 80 is configured so that the rate of change of the inverter's maximum output current Imax relative to a change in the coolant temperature Tc is smaller in the first coolant temperature region W1 that is lower than the first inflection point P1 than in the second coolant temperature region W2 that is higher than the first inflection point P1.

[0052] The controller 80 includes a coolant temperature acquisition unit that acquires the coolant temperature Tc detected by the coolant temperature sensor 53 and a first determination unit that determines whether the coolant temperature Tc is in a first coolant temperature region W1 or a second coolant temperature region W2. The controller 80 further includes an operation unit that sets a rate of change of the inverter's maximum output current Imax with respect to the coolant temperature Tc to a first gradient S1 if the first determination unit determines that the coolant temperature Tc is in the first coolant temperature region W1, and that sets a rate of change of the inverter's maximum output current Imax with respect to the coolant temperature Tc to a second gradient S2 if the first determination unit determines that the coolant temperature Tc is in the second coolant temperature region W2. The first gradient S1 is smaller than the second gradient S2. The relationship between the gradients of the change rates is second gradient S2 > first gradient S1.

[0053] The first inflection point P1 may be the only inflection point in the negative correlation. The first inflection point P1 may be any one of multiple inflection points in the negative correlation on the temperature axis. The first inflection point P1 may be any one of multiple inflection points adjacent to each other along the temperature axis.

[0054] The rate of change in the negative correlation is set to change linearly. In a temperature range lower than the first inflection point P1, the rate of change of the maximum output current Imax of the inverter with respect to the coolant temperature Tc may be set to change linearly. In a temperature range higher than the first inflection point P1, the rate of change of the maximum output current Imax of the inverter with respect to the coolant temperature Tc may be set to change linearly.

[0055] Modification 1 of the First Embodiment The following describes Modification 1, focusing on differences from the first embodiment, with reference to the drawings. In this embodiment, the method of inverter control executed by the controller 80 is changed. In addition, in the second embodiment, the drive system of the first embodiment will be described as an example of the basic structure.

[0056] Fig. 6 is a curve diagram showing the relationship between the maximum output current of the inverter and the coolant temperature in Modification 1 of the first embodiment. Fig. 7 is a flowchart showing steps of inverter control in Modification 1 of the first embodiment.

[0057] 6, in this first modification, a second inflection point P2, i.e., a limit temperature Tlimit, is provided in a region lower than the first inflection point P1. This divides the coolant temperature region into a first coolant temperature region W1, a second coolant temperature region W2, and a third coolant temperature region W3. Of these, the first coolant temperature region W1 is located between the first inflection point P1 and the second inflection point P2, the second coolant temperature region W2 is on the higher temperature side than the first inflection point P1, and the third coolant temperature region W3 is on the lower temperature side than the second inflection point P2.

[0058] In the first coolant temperature region W1, the maximum output current Imax of the inverter 30 increases at a first gradient S1 as the coolant temperature decreases. In the second coolant temperature region W2, the maximum output current Imax of the inverter 30 decreases at a second gradient S2. In the third coolant temperature region W3, the maximum output current Imax of the inverter 30 increases at a third gradient S3 as the coolant temperature decreases. The relationship between the first gradient S1, the second gradient S2, and the third gradient S3 is set as S2>S1>S3.

[0059] Next, inverter control executed by the controller 80 in the first modification of the first embodiment will be described with reference to FIG.

[0060] FIG. 7 is a flowchart showing inverter control steps in the first modification of the first embodiment.

[0061] In step S21, the temperature of the coolant flowing through the inverter 30 detected by the coolant temperature sensor 53, that is, the coolant temperature Tc, is acquired (corresponding to a coolant temperature acquisition unit).

[0062] Thereafter, in step S22, it is determined whether or not the coolant temperature Tc acquired in step S21 exceeds the heat-resistant critical temperature Tmax of the inverter 30 (corresponding to a first determination unit).

[0063] If the determination result in step S22 is negative, that is, if the coolant temperature Tc is equal to or lower than the heat-resistant critical temperature Tmax of the inverter 30, the process proceeds to step S23. If the determination result in step S22 is positive, the controller 80 decreases the maximum output current Imax of the inverter 30 at a second gradient S2 in step S24.

[0064] In step S23, it is determined whether the coolant temperature Tc exceeds the limit temperature Tlimit of the inverter 30 (corresponding to a second determination unit). If the determination result in step S23 is negative, in step S25 the controller 80 increases the maximum output current Imax of the inverter 30 at a third gradient S3 as the coolant temperature decreases. If the determination result in step S23 is positive, in step S26 the controller 80 increases the maximum output current Imax of the inverter 30 at a first gradient S1 as the coolant temperature decreases. The processes of steps S24, S25, and S26 correspond to an operation unit.

[0065] As in the first embodiment, the inverter control executed by the controller 80 is repeatedly executed at predetermined time intervals.

[0066] In this case, the negative correlation has multiple inflection points adjacent to each other along the temperature axis. In this case, the negative correlation includes, in addition to the first inflection point P1, at least one second inflection point P2 on the lower temperature side than the first inflection point P1. The negative correlation may include the above-mentioned relative magnitude relationship of the rate of change and the magnitude relationship of the slope of the rate of change for both the first inflection point P1 and the second inflection point P2. For example, the rate of change of the maximum output current Imax of the inverter relative to the coolant temperature Tc is smaller in a temperature range lower than the inflection point P1 (or P2) than in a temperature range higher than the inflection point P1 (or P2). In this case, the controller 80 further includes a second determination unit that determines whether the coolant temperature Tc is in a third coolant temperature range W3 lower than the second inflection point P2. When the second determination unit determines that the coolant temperature Tc is in the third coolant temperature region W3, the operation unit of the controller 80 sets the rate of change of the inverter's maximum output current Imax with respect to the coolant temperature Tc to a third gradient S3. The third gradient S3 is smaller than the first gradient S1. Therefore, the relationship of the gradients of the change rates is second gradient S2 > first gradient S1 > third gradient S3.

[0067] The rate of change in the negative correlation is set to change linearly. In a temperature range lower than the second inflection point P2, the rate of change of the maximum output current Imax of the inverter with respect to the coolant temperature Tc may be set to change linearly. In a temperature range higher than the second inflection point P2, the rate of change of the maximum output current Imax of the inverter with respect to the coolant temperature Tc may be set to change linearly. The negative correlation may have multiple inflection points and divide multiple temperature ranges. In this case, the rate of change in each of the multiple temperature ranges may be set to change linearly.

[0068] The above-described first modification can achieve the same effects as the first embodiment. In addition, a second inflection point P2 is set in a region lower in temperature than the first inflection point P1, and in a third coolant temperature region W3 lower in temperature than the second inflection point P2, the maximum output current Imax of the inverter 30 is increased at a second gradient S2 smaller than the first gradient S1. In other words, the maximum output current Imax of the inverter 30 is increased more gradually.

[0069] By setting it in this way, it is possible to suppress the increase in the maximum output current of the inverter in low temperature regions such as when the road surface is frozen, thereby achieving optimal driving performance.

[0070] Second embodiment The second embodiment will be described below with reference to the drawings, focusing on the differences from the first embodiment. In the second embodiment, the drive system of the first embodiment will be used as an example of the basic structure.

[0071] As described above, the inverter 30 converts the DC power from the storage battery 40 into AC power and outputs it. Therefore, the DC voltage of the DC power from the storage battery 40 also affects the heat generation of the inverter 30.

[0072] Therefore, in this embodiment, the vehicle MV includes a voltage sensor that detects the terminal voltage of the capacitor 31 and uses it as the DC voltage from the storage battery 40.

[0073] The controller 80 further controls the maximum output current of the inverter 30 based on the detected DC voltage value from the voltage sensor. Specifically, the controller 80 is configured so that the maximum output current of the inverter 30 increases as the detected DC voltage value decreases.

[0074] Therefore, in this embodiment, an additional control is performed in addition to the preceding embodiment. In this embodiment, the mobile object further includes a voltage sensor. The voltage sensor detects the DC voltage from the power storage unit. The controller 80 is configured to control the output current of the inverter so that the maximum output current Imax of the inverter increases as the detected DC voltage value decreases.

[0075] Third embodiment The third embodiment will be described below with reference to the drawings, focusing on the differences from the first embodiment. In the third embodiment, the drive system of the first embodiment will be used as an example of the basic structure.

[0076] As described above, the controller 80 performs switching control of the inverter 30 by, for example, PWM control at a predetermined switching frequency (carrier frequency), and uses the control amount of the rotating electrical machine 20, for example, torque feedback control, as its command value. The lower the switching frequency, the less heat the inverter 30 generates.

[0077] Therefore, in this embodiment, the controller 80 further controls the inverter based on the switching frequency of the PWM control. Specifically, the controller 80 is configured so that the maximum output current of the inverter 30 increases as the switching frequency decreases.

[0078] Therefore, in this embodiment, an additional control is performed in addition to the preceding embodiment. In this embodiment, the controller 80 is configured to control the output current of the inverter such that the lower the switching frequency of the switching control, the higher the maximum output current Imax of the inverter.

[0079] Fourth embodiment The fourth embodiment will be described below with reference to the drawings, focusing on the differences from the first embodiment. In the fourth embodiment, the drive system of the first embodiment will be used as an example of the basic structure.

[0080] As described above, the cooling water flowing into the cooler 51 is cooled by the wind blowing into the cooler 51 as the vehicle MV travels.

[0081] In other words, the faster the vehicle MV moves, the lower the coolant temperature becomes.

[0082] Therefore, in this embodiment, the controller 80 also controls the inverter based on the travel speed of the vehicle MV. Specifically, the controller 80 is configured so that the maximum output current of the inverter 30 increases as the travel speed of the vehicle MV increases.

[0083] Therefore, in this embodiment, in addition to the preceding embodiment, an additional control is performed. In this embodiment, the controller 80 is configured to control the output current of the inverter so that the maximum output current Imax of the inverter increases as the moving speed of the moving object increases.

[0084] Fifth embodiment The fifth embodiment will be described below with reference to the drawings, focusing on the differences from the first embodiment. In the fifth embodiment, the drive system of the first embodiment will be used as an example of the basic structure.

[0085] As described above, the cooling water flowing into the cooler 51 is cooled by the wind blown into the cooler 51 by driving the rotation of the fan 52 .

[0086] In other words, the faster the rotation speed of the fan 52, the lower the cooling water temperature.

[0087] Therefore, in this embodiment, the controller 80 further controls the inverter based on the rotation speed of the fan 52. Specifically, the controller 80 is configured so that the maximum output current of the inverter 30 increases as the rotation speed of the fan 52 increases.

[0088] Therefore, in this embodiment, an additional control is performed in addition to the preceding embodiment. In this embodiment, the cooling mechanism has a fan 52. The fan 52 supplies cooling air to the cooler 51. The fan 52 is connected to a power source with an adjustable rotation speed. The power source can be provided by an electric motor, a hydraulic motor, or the like. The controller 80 is configured to control the output current of the inverter so that the higher the rotation speed of the fan 52, the higher the maximum output current Imax of the inverter.

[0089] Other embodiments The disclosure in this specification and the drawings, etc. is not limited to the exemplified embodiments. The disclosure encompasses the exemplified embodiments and variations thereon that may be made by those skilled in the art. For example, the disclosure is not limited to the combinations of parts and / or elements shown in the embodiments. The disclosure can be implemented in various combinations. The disclosure may have additional parts that can be added to the embodiments. The disclosure encompasses the omission of parts and / or elements from the embodiments. The disclosure encompasses the substitution or combination of parts and / or elements between one embodiment and another embodiment. The disclosed technical scope is not limited to the description of the embodiments. Some disclosed technical scopes are defined by the claims, and should be interpreted as including all modifications within the meaning and scope of the claims.

[0090] Furthermore, each of the above embodiments can be modified as follows.

[0091] The semiconductor switches that make up the inverter are not limited to IGBTs, but can also be, for example, N-channel MOSFETs with built-in body diodes. In such cases, the high-potential terminal of the switch becomes the drain, and the low-potential terminal becomes the source.

[0092] The rotating electric machine is not limited to a star-connected rotating electric machine, but may be, for example, a delta-connected rotating electric machine.

[0093] The control unit and the method described herein can be implemented by a special-purpose computer, which can be configured with a processor and memory. The processor is programmed to perform one or more functions embodied in a computer program. Alternatively, the control unit and the method described herein can be implemented by a special-purpose computer, which can be configured with a processor configured with one or more dedicated hardware logic circuits. Alternatively, the control unit and the method described herein can be implemented by one or more special-purpose computers, which can be configured by combining a processor programmed to perform one or more functions, memory, and a processor configured with one or more hardware logic circuits. Furthermore, the computer program can be stored in a computer-readable, non-transitory physical storage medium as instructions to be executed by a computer.

[0094] Although the present disclosure has been described based on the embodiments, it should be understood that the present disclosure is not limited to the above-described embodiments and structures. The present disclosure also includes various modifications and variations within the same scope. In addition, various combinations and forms, as well as other combinations and forms of only one element, more than one, or less than one element, are also within the scope and concept of the present disclosure.

[0095] (Disclosure of technical ideas) This specification discloses multiple technical ideas described in the following multiple clauses. Some clauses may be written in a multiple dependent form, with the subsequent clause referring to the preceding clause as an alternative. Furthermore, some clauses may be written in a multiple dependent form, referring to another multiple dependent clause. These multiple dependent clauses define multiple technical ideas.

[0096] (Technical thought 1) a rotating electric machine (20) including a rotor and a stator having a stator winding including a plurality of phase windings; a power storage unit (40); an inverter (30) having a series connection of an upper arm switch and a lower arm switch, and converting DC power supplied from the power storage unit into AC power by switching control and supplying the AC power to the rotating electric machine; a cooling mechanism that cools the inverter with a cooling medium; A control device (80) for a moving body (MV) that is equipped with a cooling medium temperature sensor that detects the temperature of the cooling medium flowing through the inverter, the control device is configured to control an output current of the inverter; the control device is configured to have a negative correlation between a maximum output current (Imax) of the inverter and a cooling medium temperature (Tc), and the negative correlation has at least one inflection point; the control device is configured to have a first inflection point (P1) as the inflection point, The control device is configured so that the rate of change of the maximum output current of the inverter with respect to the cooling medium temperature is smaller in a first cooling medium temperature region (W1) lower than the first inflection point than in a second cooling medium temperature region (W2) higher than the first inflection point.

[0097] (Technical thought 2) a coolant temperature acquisition unit that acquires the coolant temperature detected by the coolant temperature sensor; a first determination unit that determines whether the cooling medium temperature is in the first cooling medium temperature region or the second cooling medium temperature region; when the first determination unit determines that the cooling medium temperature is in the first cooling medium temperature region, setting a rate of change of a maximum output current of the inverter with respect to the cooling medium temperature to a first gradient (S1); A control device for a moving body described in Technical Idea 1, comprising an operation unit that sets the rate of change of the maximum output current of the inverter with respect to the cooling medium temperature to a second gradient (S2) greater than the first gradient when the first judgment unit determines that the cooling medium temperature is in the second cooling medium temperature region.

[0098] (Technical Thought 3) The inflection points further include at least one second inflection point (P2) on the lower temperature side than the first inflection point, A control device for a moving body according to Technical Idea 1 or Technical Idea 2, in which the rate of change of the maximum output current of the inverter with respect to the cooling medium temperature is made smaller in a temperature region lower than the inflection point compared to a temperature region higher than the inflection point.

[0099] (Technical Thought 4) a second determination unit that determines whether the cooling medium temperature is in a third cooling medium temperature region (W3) that is lower than the second inflection point; A control device for a moving body described in Technical Idea 2 or Technical Idea 3, wherein when the second judgment unit determines that the cooling medium temperature is in the third cooling medium temperature region, the operation unit sets the rate of change of the maximum output current of the inverter with respect to the cooling medium temperature to a third slope (S3) that is greater than the first slope.

[0100] (Technical Thought 5) A control device for a moving body according to any one of Technical Ideas 1 to 4, wherein in a temperature region lower than the first inflection point, the rate of change of the maximum output current of the inverter with respect to the cooling medium temperature changes linearly.

[0101] (Technical Thought 6) the moving object further includes a voltage sensor, the voltage sensor detecting a DC voltage from the power storage unit; The control device for a moving body according to any one of Technical Ideas 1 to 5, wherein the control device is configured such that the smaller the detected value of the DC voltage, the larger the maximum output current of the inverter.

[0102] (Technical Thought 7) The control device for a moving body according to any one of Technical Ideas 1 to 6, wherein the control device is configured such that the maximum output current of the inverter increases as the switching frequency of the switching control decreases.

[0103] (Technical Thought 8) The control device for a moving body according to any one of Technical Ideas 1 to 7, wherein the control device is configured such that the maximum output current of the inverter increases as the moving speed of the moving body increases.

[0104] (Technical Thought 9) The cooling mechanism has a fan (52), The control device for a moving body according to any one of Technical Ideas 1 to 8, wherein the control device is configured such that the maximum output current of the inverter increases as the rotation speed of the fan increases.

[0105] (Technical Thought 10) a rotating electric machine (20) including a rotor and a stator having a stator winding including a plurality of phase windings; a power storage unit (40); an inverter (30) having a series connection of an upper arm switch and a lower arm switch, and converting DC power supplied from the power storage unit into AC power by switching control and supplying the AC power to the rotating electric machine; a cooling mechanism that cools the inverter with a cooling medium; a cooling medium temperature sensor (53) for detecting the temperature of the cooling medium flowing through the inverter; a computer as a control device, and a program for causing the control device to execute a control process for controlling an output current of the inverter, the program comprising: A process of acquiring a coolant temperature (Tc) detected by the coolant temperature sensor; a process of setting the maximum output current (Imax) according to the cooling medium temperature (Tc) based on a negative correlation that is set between the cooling medium temperature (Tc) and the maximum output current (Imax) of the inverter, the negative correlation having at least one inflection point, wherein a rate of change of the maximum output current of the inverter with respect to the cooling medium temperature is smaller in a temperature region lower than the inflection point compared to a temperature region higher than the inflection point; and controlling the output current of the inverter based on the maximum output current (Imax).

[0106] (Technical Thought 11) A computer-readable storage medium storing a program for causing a computer to execute the control process described in Technical Idea 10. [Explanation of symbols]

[0107] 20 rotating electric machine, 21 current sensor, 22 rotation angle sensor, 30 inverters, 40 storage batteries, 50 circulation path, 51 cooler, 52 fan, 54 water pump, 80 controllers, P1: First inflection point, P2: Second inflection point W1 first cooling water temperature region, W2 second cooling water temperature region, W3 Third coolant temperature region.

Claims

1. A rotating electric machine (20) including a rotor and a stator having a stator winding including a plurality of phase windings; A power storage unit (40); an inverter (30) having a series connection of an upper arm switch and a lower arm switch, and converting DC power supplied from the power storage unit into AC power by switching control and supplying the AC power to the rotating electric machine; a cooling mechanism that cools the inverter with a cooling medium; A control device (80) for a moving body (MV) that is equipped with a cooling medium temperature sensor that detects the temperature of the cooling medium flowing through the inverter, the control device is configured to control an output current of the inverter; the control device is configured to have a negative correlation between a maximum output current (Imax) of the inverter and a cooling medium temperature (Tc), and the negative correlation has at least one inflection point; the control device is configured to have a first inflection point (P1) as the inflection point, The control device is configured so that the rate of change of the maximum output current of the inverter with respect to the cooling medium temperature is smaller in a first cooling medium temperature region (W1) lower than the first inflection point than in a second cooling medium temperature region (W2) higher than the first inflection point.

2. a coolant temperature acquisition unit that acquires the coolant temperature detected by the coolant temperature sensor; a first determination unit that determines whether the cooling medium temperature is in the first cooling medium temperature region or the second cooling medium temperature region; when the first determination unit determines that the cooling medium temperature is in the first cooling medium temperature region, setting a rate of change of a maximum output current of the inverter with respect to the cooling medium temperature to a first gradient (S1); 2. The control device for a moving body according to claim 1, further comprising: an operation unit that, when the first determination unit determines that the cooling medium temperature is in the second cooling medium temperature region, sets a rate of change of a maximum output current of the inverter with respect to the cooling medium temperature to a second gradient (S2) that is greater than the first gradient.

3. The inflection points further include at least one second inflection point (P2) on the lower temperature side than the first inflection point, 2. The control device for a moving body according to claim 1, wherein a rate of change of a maximum output current of the inverter with respect to the cooling medium temperature is made smaller in a temperature region lower than the inflection point compared to a temperature region higher than the inflection point.

4. a second determination unit that determines whether the cooling medium temperature is in a third cooling medium temperature region (W3) that is lower than the second inflection point; 3. The control device for a moving body according to claim 2, wherein, when the second determination unit determines that the cooling medium temperature is in the third cooling medium temperature region, the operation unit sets a rate of change of the maximum output current of the inverter with respect to the cooling medium temperature to a third gradient (S3) that is greater than the first gradient.

5. The control device for a moving body according to claim 1 , wherein a rate of change of the maximum output current of the inverter with respect to the cooling medium temperature changes linearly in a temperature region lower than the first inflection point.

6. the moving object further includes a voltage sensor, the voltage sensor detecting a DC voltage from the power storage unit; The control device for a moving body according to claim 1 , wherein the control device is configured such that the maximum output current of the inverter increases as the detected value of the DC voltage decreases.

7. The control device for a moving body according to claim 1 , wherein the control device is configured such that the maximum output current of the inverter increases as the switching frequency of the switching control decreases.

8. The control device for a moving body according to claim 1 , wherein the control device is configured such that the maximum output current of the inverter increases as the moving speed of the moving body increases.

9. The cooling mechanism includes a fan (52); The control device for a moving body according to claim 1 , wherein the control device is configured such that the maximum output current of the inverter increases as the rotation speed of the fan increases.

10. A rotating electric machine (20) including a rotor and a stator having a stator winding including a plurality of phase windings; A power storage unit (40); an inverter (30) having a series connection of an upper arm switch and a lower arm switch, and converting DC power supplied from the power storage unit into AC power by switching control and supplying the AC power to the rotating electric machine; a cooling mechanism that cools the inverter with a cooling medium; a cooling medium temperature sensor (53) for detecting the temperature of the cooling medium flowing through the inverter; a computer as a control device, and a program for causing the control device to execute a control process for controlling an output current of the inverter, the program comprising: A process of acquiring a cooling medium temperature (Tc) detected by the cooling medium temperature sensor; a process of setting the maximum output current (Imax) according to the cooling medium temperature (Tc) based on a negative correlation that is set between the cooling medium temperature (Tc) and the maximum output current (Imax) of the inverter, the negative correlation having at least one inflection point, wherein a rate of change of the maximum output current of the inverter with respect to the cooling medium temperature is smaller in a temperature region lower than the inflection point compared to a temperature region higher than the inflection point; and controlling the output current of the inverter based on the maximum output current (Imax).

11. A computer-readable storage medium storing a program for causing a computer to execute the control process according to claim 10.

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