Motor control device and motor control method

Abstract

To prevent excessive increasing of motor current flowing into a motor when an engine is started up.SOLUTION: A control device 60 acquires a rotation speed detected by a rotation speed sensor 42 when an engine is started up by an MG 21. The control device 60 acquires, based on a torque map 65, an upper limit value and a lower limit value that are associated with the acquired rotation speed. When a previous command value set previously is smaller than the lower limit value, the control device 60 sets the present command value to the lower limit value. When the previous command value is larger than the upper limit value, the control device 60 sets the present command value to the upper limit value. When the previous command value is larger than the lower limit value and smaller than the upper limit value, the control device 60 sets the present command value to the same value as the previous command value.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present disclosure relates to a motor control device and a motor control method. [Background technology]

[0002] Japanese Patent Application Laid-Open Publication No. 2019-19842 (Patent Document 1) discloses a vehicle having an engine and an alternator that assists in starting the engine. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2019-19842 Summary of the Invention [Problem to be solved by the invention]

[0004] In the above-described technology, a configuration in which the alternator is replaced by a motor can be considered. In a vehicle employing such a configuration, a problem can arise in that the motor current flowing through the motor becomes excessive when the engine is started.

[0005] The present disclosure has been made to solve such problems, and its purpose is to prevent the motor current flowing through the motor from becoming excessive when the engine is started. [Means for solving the problem]

[0006] (1) A motor control device disclosed herein includes a motor, a control device, a sensor, and a storage device. The motor is connected to an engine. The control device periodically sets a command value for the motor's torque. The sensor detects the motor's rotational speed. The storage device stores command value information in which an upper limit value and a lower limit value of the command value are defined in association with the motor's rotational speed. When starting the engine using the motor, the control device acquires the rotational speed detected by the sensor. The control device acquires the upper limit value and the lower limit value associated with the acquired rotational speed based on the command value information. If a previous command value set last time is smaller than the lower limit value, the control device sets the current command value to the lower limit value. If the previous command value is greater than the upper limit value, the control device sets the current command value to the upper limit value. If the previous command value is greater than the lower limit value and smaller than the upper limit value, the control device sets the current command value to the same value as the previous command value.

[0007] With this configuration, it is possible to suppress changes in the command value for the torque of the motor, and therefore it is possible to prevent the motor current flowing through the motor from becoming excessive when the engine is started.

[0008] (2) In the motor control device described in (1), the upper limit value is a value determined based on the suppression of overcurrent to the motor.

[0009] This configuration prevents the motor torque command value from exceeding the upper limit, which is the value based on which overcurrent to the motor is suppressed, and therefore prevents the motor current flowing to the motor when the engine is started from becoming excessive.

[0010] (3) In the motor control device according to (1) or (2), the lower limit value is a value that is determined based on the fact that stopping of the engine is suppressed.

[0011] This configuration prevents the motor torque command value from falling below the lower limit, which is the value based on which engine stoppage is prevented, and therefore prevents the engine from stopping when the motor is started.

[0012] (4) In the motor control device according to any one of (1) to (3), the command value information is defined such that the upper limit value and the lower limit value become smaller as the rotation speed increases.

[0013] With this configuration, the torque command value can be reduced when the rotation speed of the motor increases, thereby enabling the motor to be started appropriately.

[0014] (5) A motor control method disclosed herein is a method for controlling a motor connected to an engine. The motor control method includes periodically setting a command value for motor torque. Setting the command value includes acquiring a rotational speed of the motor when starting the engine with the motor. Setting the command value includes acquiring an upper limit value and a lower limit value associated with the acquired rotational speed. Setting the command value includes setting a current command value to the lower limit value when a previous command value set previously is smaller than the lower limit value. Setting the command value includes setting the current command value to the upper limit value when the previous command value is greater than the upper limit value. Setting the command value includes setting the current command value to the same value as the previous command value when the previous command value is greater than the lower limit value and less than the upper limit value. [Effects of the Invention]

[0015] In the present disclosure, it is possible to prevent the motor current flowing through the motor from becoming excessive when the engine is started. [Brief explanation of the drawings]

[0016] [Figure 1] 1 is a diagram showing a schematic configuration of a hybrid vehicle according to an embodiment; [Figure 2]4 is an example of a torque map according to the embodiment. [Figure 3] 10 is an example of a simulation result of a motor control device of a comparative example. [Figure 4] FIG. 2 is a functional block diagram of the motor control device. [Figure 5] FIG. 4 is a diagram schematically showing a torque map. [Figure 6] 10 is a flowchart executed by the control device 60. [Figure 7] 10 is a flowchart of a command value setting process. [Figure 8] 10 is an example of a simulation result of the motor control device according to the present embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0017] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are designated by the same reference numerals, and description thereof will not be repeated. [Overall configuration] Fig. 1 is a diagram showing a schematic configuration of a hybrid vehicle 1 according to an embodiment. As shown in Fig. 1, the hybrid vehicle 1 includes an engine 11, a transmission 12, a starter 19, a motor generator (hereinafter also referred to as "MG21"), an inverter 22, a high-voltage battery 23, a DC / DC converter 25, a low-voltage battery 26, accessories 27, a battery management system 28 (hereinafter also referred to as "BMS28"), drive wheels 30, a crank angle sensor 41, a rotational speed sensor 42, a motor current sensor 43, a vehicle ECU (Electronic Control Unit) 51, an engine ECU 52, and a motor ECU 53. The hybrid vehicle 1 uses the engine 11 and the MG21 as drive sources. The MG21 corresponds to the "motor" in this disclosure.

[0018] The engine 11 is an internal combustion engine having a plurality of cylinders 13 and a plurality of fuel injection valves 15 provided in each of the cylinders 13. Each fuel injection valve 15 is driven by a control signal from the engine ECU 52 and injects fuel into the corresponding cylinder 13.

[0019] One end of the crankshaft 11A of the engine 11 is connected to the drive wheels 30 via the transmission 12. The other end of the crankshaft 11A is connected to a first pulley 16. A transmission belt 17 is wound around the first pulley 16. Although not shown, the crankshaft 11A of the engine 11 is also connected to a hydraulic pump for generating hydraulic pressure via a belt, pulleys, gears (sprockets), chains, and the like.

[0020] The engine 11 is provided with a crank angle sensor 41. The crank angle sensor 41 outputs a detection signal corresponding to the rotation angle of the crankshaft 11A (i.e., the crank angle) to the vehicle ECU 51 and the engine ECU 52. The vehicle ECU 51 and the engine ECU 52 detect the crank angle and the rotation speed of the engine 11 (hereinafter also referred to as "engine rotation speed") based on the output of the crank angle sensor 41.

[0021] The transmission 12 is a transmission connected between the engine 11 and the drive wheels 30, and serves to adjust the torque output from the engine 11 based on a gear ratio (speed ratio) and transmit the torque to the drive wheels 30. The gear ratio indicates the ratio between the engine speed for each gear position (gear stage) and the speed changed by the transmission 12 (the speed of rotation output from the transmission 12).

[0022] The MG21 converts electrical energy into mechanical energy and vice versa. The MG21 is, for example, a three-phase AC synchronous rotating electric machine with a permanent magnet embedded in the rotor. One end of a rotating shaft 21A of the MG21 is connected to a second pulley 18. A transmission belt 17 is wound around the second pulley 18. That is, the MG21 is connected to a crankshaft 11A of the engine 11 via the second pulley 18, the transmission belt 17, and the first pulley 16. The transmission belt 17 is wound around the first pulley 16 and the second pulley 18. Furthermore, a belt tensioner 31 applies a predetermined tension to the transmission belt 17. The MG21 is connected to the engine 11 so as to be able to transmit power therebetween. The MG21 and the engine 11 are also connected via a predetermined member. The predetermined members in FIG. 1 are the crankshaft 11A, the rotary shaft 21A, the first pulley 16, the second pulley 18, and the transmission belt 17.

[0023] When functioning as an electric motor, the MG 21 generates torque for the drive wheels 30 using electric power supplied from the high-voltage battery 23. Specifically, when the MG 21 functions as an electric motor, a rotor (for example, a rotor) of the MG 21 rotates, and thereby a rotational torque is applied from the MG 21 to the second pulley 18. The rotational torque is then input to the crankshaft 11A of the engine 11 via the transmission belt 17 and the first pulley 16. This allows the MG 21 to assist the driving of the engine 11, thereby assisting the running of the hybrid vehicle 1.

[0024] When functioning as a generator, the MG 21 generates electricity using the driving force of the engine 11. Specifically, when the MG 21 functions as a generator, the rotational torque of the crankshaft 11A of the engine 11 is input to the rotating shaft 21A of the MG 21 via the first pulley 16, the transmission belt 17, and the second pulley 18. The MG 21 generates electricity in response to the rotation of the rotating shaft 21A.

[0025] The MG 21 is electrically connected to the high-voltage battery 23 via an inverter 22. The inverter 22 is a so-called bidirectional inverter. In accordance with a control signal from the motor ECU 53, the inverter 22 converts AC power generated by the MG 21 into DC power and outputs the DC power to the high-voltage battery 23. The inverter 22 also converts DC power supplied from the high-voltage battery 23 into AC power and outputs the AC power to the MG 21.

[0026] The motor current sensor 43 is provided in the MG 21 and measures the current flowing through the MG 21. For example, if the MG 21 is a three-phase AC synchronous rotating electric machine, the motor current sensor 43 measures the current of each phase of the MG 21.

[0027] The high-voltage battery 23 is, for example, a 48 V lithium-ion battery. Note that the high-voltage battery 23 is not limited to a lithium-ion battery, and may be another secondary battery (for example, a nickel-metal hydride battery) or an all-solid-state secondary battery.

[0028] When the MG 21 functions as an electric motor, the high-voltage battery 23 supplies power to the MG 21 via the inverter 22. When the MG 21 functions as a generator, the high-voltage battery 23 receives power generated by the MG 21 via the inverter 22, thereby being charged.

[0029] The BMS 28 measures the current value, voltage value, and state of charge (SOC) of the high-voltage battery 23. The measured values ​​of the BMS 28 are input to the vehicle ECU 51.

[0030] DC / DC converter 25 is connected to MG 21 via inverter 22. DC / DC converter 25 is also connected to high-voltage battery 23. DC / DC converter 25 steps down the DC voltages output from inverter 22 and high-voltage battery 23 to 12 V to 15 V, and outputs the voltages to auxiliary equipment 27 and low-voltage battery 26.

[0031] The low-voltage battery 26 is connected to the DC / DC converter 25. The low-voltage battery 26 is a 12V lead-acid battery having a lower voltage than the high-voltage battery 23. The low-voltage battery 26 outputs a direct current voltage of 12V when the DC / DC converter 25 is not operating or when the output voltage of the DC / DC converter 25 is 12V. The low-voltage battery 26 is charged by receiving power from the DC / DC converter 25 when the output voltage of the DC / DC converter 25 is higher than the open circuit voltage (OCV) of the low-voltage battery 26.

[0032] Various accessories (vehicle electrical equipment) 27 are connected to the DC / DC converter 25 and the low-voltage battery 26. The accessories 27 include, for example, lighting-related components such as vehicle headlights, turn signals, and interior lights, as well as interior equipment such as a car navigation system or speakers. The accessories 27 are supplied with power from the low-voltage battery 26 when the DC / DC converter 25 is not operating. The accessories 27 are supplied with power from the DC / DC converter 25 when the output voltage of the DC / DC converter 25 is higher than the open-circuit voltage (OCV) of the low-voltage battery 26.

[0033] A starter 19 is connected to the DC / DC converter 25 and the low-voltage battery 26 as one of the accessories 27. The starter 19 is a DC motor, and an output shaft of the starter 19 is connected to the crankshaft 11A of the engine 11. The starter 19 is driven by power supplied from the low-voltage battery 26 or the DC / DC converter 25.

[0034] The rotation speed sensor 42 is provided in the MG 21 and detects the rotation speed of the MG 21. The detection value of the rotation speed sensor 42 is input to the vehicle ECU 51.

[0035] Each of the vehicle ECU 51, the engine ECU 52, and the motor ECU 53 includes a central processing unit (CPU) as a computing device, a storage device, and input / output ports for inputting and outputting various signals (not shown). The storage device includes a random access memory (RAM) as a working memory and a storage device (a rewritable nonvolatile memory such as a read-only memory (ROM) or an EEPROM).

[0036] The vehicle ECU 51 also has a control device 60 and a storage device 61. The control device 60 is configured with a CPU and a part of the storage device. The storage device 61 is configured with at least a part of the above-mentioned storage device. The vehicle ECU 51 may also be referred to as a control device, and the vehicle ECU 51, engine ECU 52, and motor ECU 53 may also be collectively referred to as a "control device." The control device may also be referred to as a "control circuit."

[0037] The vehicle ECU 51, engine ECU 52, and motor ECU 53 receive signals from various devices (sensors, etc.) connected to their input ports and control various devices connected to their output ports based on the received signals. Various controls are performed by the CPU executing programs stored in the storage device. The controls performed by the vehicle ECU 51, engine ECU 52, and motor ECU 53 are not limited to software processing, but can also be realized by processing using dedicated hardware (electronic circuits).

[0038] The vehicle ECU 51 calculates (sets) an output command value (for example, a fuel injection amount) for the engine 11 and an output command value (for example, a command torque value described later) for the MG 21. The vehicle ECU 51 outputs the output demand value for the engine 11 to the engine ECU 52, and outputs the output demand value for the MG 21 to the motor ECU 53.

[0039] The vehicle ECU 51 sets the command torque value periodically (for example, at predetermined intervals). The predetermined interval is, for example, 0.1 seconds. In this embodiment, "periodically setting the command torque value" includes both an example in which the timing at which the command torque value is set and the timing at which the next command torque value is set are the same for multiple periods, and an example in which the multiple periods are slightly different.

[0040] The motor ECU 53 controls the supply of power to the MG 21 via the inverter 22 based on the command torque value input from the vehicle ECU 51. More specifically, the motor ECU 53 sets a command value (hereinafter referred to as a set command value) based on the command torque value, and controls the inverter 22 so that the actual torque output by the MG 21 becomes the set command value.

[0041] The engine ECU 52 performs operation control (such as fuel injection control) of the engine 11 based on an output requirement value (for example, engine required torque) input from the vehicle ECU 51. For example, when a fuel injection amount control signal is input from the vehicle ECU 51, the engine ECU 52 controls the fuel injection valve 15 so that the input fuel injection amount of fuel is injected into the cylinder 13. In other words, the vehicle ECU 51 controls the fuel injection amount per injection from the fuel injection valve 15 of the engine 11 via the engine ECU 52. In this way, the engine 11 generates actual torque for the drive wheels 30.

[0042] Furthermore, when a request to start the engine 11 is made while the engine 11 is stopped, the vehicle ECU 51 starts the engine 11 by cranking the engine 11 using the starter 19 or the MG 21. The start request is made, for example, when the driver depresses the accelerator pedal.

[0043] When a start request is made, the vehicle ECU 51 cranks the engine 11 using the starter 19 or the MG 21, and when the engine rotation speed reaches a predetermined starting rotation speed through cranking, the vehicle ECU 51 injects fuel from the fuel injection valve 15 to start the engine 11. In this manner, the period from when the starter 19 or the MG 21 begins to start the engine 11 until the MG 21 stabilizes is also referred to as the "starting period." The starter 19 or the MG 21 may also be referred to as the "cranking mechanism."

[0044] [Motor control device of comparative example] First, the starting of the motor generator of the motor control device of the comparative example will be described. When starting the MG, the motor control device of the comparative example uses a predetermined torque map to set a command torque value for the MG. Figure 2 shows an example of this torque map.

[0045] In the example of Fig. 2, the horizontal axis specifies the MG rotation speed, and the vertical axis specifies the command torque value. In the example of Fig. 2, the command torque value is specified so that the faster the MG rotation speed, the smaller the command torque value.

[0046] FIG. 3 shows an example of the MG rotation speed, command torque value, realized torque value, and MG current value in a motor control device of a comparative example. The horizontal axis in FIGS. 3(A) to 3(D) represents time. The vertical axis in FIG. 3(A) represents the MG rotation speed. The vertical axis in FIG. 3(B) represents the command torque value. As described above, the command torque value is a value that is periodically set by the vehicle ECU. The vertical axis in FIG. 3(C) represents the realized torque value. The realized torque value is the actual torque value generated in the MG 21. The vertical axis in FIG. 3(D) represents the MG current value. The MG current is the current flowing through the MG 21. The MG current is calculated, for example, by multiplying the realized torque by the MG rotation speed.

[0047] 3A, the MG rotation speed increases while fluctuating, that is, the MG rotation speed pulsates. This pulsation is caused by the vibration of the belt tensioner 31 and the rotation pulsation of the cranking mechanism described above.

[0048] As described above, the motor control device of the comparative example sets the command torque value based on the torque map of FIG. 2. Therefore, the faster the rotation speed of the MG, the smaller the command torque value set by the motor control device so as to slow the rotation speed of the MG. Conversely, the slower the rotation speed of the MG, the larger the command torque value set by the motor control device so as to speed up the rotation speed of the MG. Since the command torque value is set in this manner, the command torque value shown in FIG. 3(B) is set.

[0049] Furthermore, the actual driving of the MG is delayed relative to the command for the MG. In other words, as shown in Fig. 3(C), the timing at which the command torque value is reflected as the realized torque value is delayed from the timing at which the command torque value is set. In Fig. 3(C), the solid line indicates the realized torque value, and the dashed line indicates the command torque value shown in Fig. 3(B).

[0050] In this way, the delay in the realized torque value relative to the command torque value increases the frequency with which the timing at which the MG rotation speed reaches its maximum value coincides with the timing at which the realized torque value is large. This coincidence timing is also simply referred to as "coincidence timing."

[0051] In the example of FIG. 3, t1 and t2 are shown as coincidence times. As described above, the MG current is calculated by multiplying the realized torque value by the MG rotation speed. Therefore, the MG current tends to increase at the coincidence times. In particular, in the latter half of the starting period, as shown in FIG. 3(A), the MG rotation speed tends to increase. Therefore, as shown in FIG. 3(D), at coincidence time t2 in the latter half of the starting period, the MG current may become excessively large and exceed the overcurrent threshold.

[0052] As described above, the motor control device of the comparative example can have a problem in that the MG current flowing through the MG becomes excessive when the MG is started. Therefore, the motor control device of this embodiment prevents the MG current from becoming excessive when the MG is started. [Motor control device functional block diagram] 4 is a functional block diagram of the motor control device 300. The motor control device 300 has an MG 21, a rotation speed sensor 42, a control device 60, and a storage device 61. The control device 60 has an acquisition unit 102 and a command unit 104.

[0053] As described in FIG. 1 , the MG 21 is connected to the engine 11. Furthermore, the rotation speed sensor 42 detects the rotation speed of the MG 21. The detected rotation speed is input to the control device 60. When starting the engine 11, the acquisition unit 102 acquires the rotation speed. The acquired rotation speed is output to the command unit 104.

[0054] The storage device 61 also stores a torque map 65. The storage device 61 is configured, for example, by a ROM etc. FIG.

[0055] In the example of FIG. 5, an upper limit value map and a lower limit value map are defined. The upper limit value indicates the upper limit of the command torque value, and the lower limit value indicates the lower limit of the command torque value. In the upper limit value map and the lower limit value map, the command torque value is defined in association with the rotation speed of the MG 21. In addition, in the upper limit value map and the lower limit value map, the command torque value is defined to be smaller as the rotation speed of the MG 21 increases. Conversely, in the upper limit value map and the lower limit value map, the command torque value is defined to be larger as the rotation speed of the MG 21 decreases. Torque map 65 corresponds to the "command value information" of the present disclosure.

[0056] The command unit 104 periodically sets a command torque value for the MG 21 (see FIG. 7, which will be described later). This setting process is also referred to as a "command value setting process." The command torque value that is currently set is also referred to as a "current command value." The command torque value that was most recently set before the current command value is also referred to as a "previous command value."

[0057] In this embodiment, when the command unit 104 sets a current command value, the command unit 104 uses the current command value as the previous command value in the next command value setting process. Therefore, when the command unit 104 sets a current command value, the command unit 104 stores the current command value in a predetermined storage area (for example, a RAM).

[0058] Furthermore, when starting the engine 11 (MG21), the command unit 104 acquires the rotation speed from the acquisition unit 102. The command unit 104 acquires the upper limit value and the lower limit value associated with the acquired rotation speed based on the torque map 65.

[0059] If the previous command value is smaller than the acquired lower limit value, the command unit 104 sets the current command value to the lower limit value. If the previous command value is larger than the upper limit value, the command unit 104 sets the current command value to the upper limit value. Also, if the previous command value is larger than the lower limit value and smaller than the upper limit value, the command unit 104 sets the current command value to the same value as the previous command value.

[0060] The command unit 104 generates a command signal indicating the set command torque value and outputs the command signal to the motor ECU 53 .

[0061] Furthermore, the upper limit value (upper limit map) is a value that is determined in advance based on the suppression of overcurrent to the MG 21 (so that overcurrent to the MG 21 is suppressed). In other words, if the command torque value is equal to or greater than the upper limit value, an overcurrent may flow to the MG 21. In other words, if the command torque value is smaller than the upper limit value, it is possible to suppress the flow of overcurrent to the MG 21.

[0062] Furthermore, the lower limit value (lower limit map) is a value that is determined based on the prevention of stopping of the engine 11 (so that the prevention of stopping of the engine 11). In other words, if the command torque value is equal to or less than the lower limit value, the engine 11 may stop (the engine 11 may not start). In other words, if the command torque value is greater than the lower limit value, the engine 11 may be started appropriately. [flowchart] Fig. 6 is an example of a flowchart executed by the control device 60 when there is a request to start the engine 11. As shown in Fig. 6, the control device 60 periodically executes a command value setting process in step S100.

[0063] 7 shows a subroutine for the command value setting process. In step S2, the control device 60 acquires the MG rotation speed from the rotation speed sensor 42 (see FIG. 4). Next, in step S4, the control device 60 refers to the torque map 65 (see FIG. 5) to acquire the upper limit value TH and the lower limit value TL corresponding to the MG rotation speed.

[0064] Next, in step S6, the control device 60 determines whether the previous command value is greater than the lower limit TL. If the previous command value is greater than the lower limit TL (YES in step S6), the process proceeds to step S8. If the previous command value is equal to or less than the lower limit TL (NO in step S6), the process proceeds to step S14.

[0065] In step S14, the control device 60 sets the current command value to the lower limit value TL, thereby enabling the control device 60 to prevent the engine 11 from stopping.

[0066] In step S8, the control device 60 determines whether the previous command value is smaller than the upper limit value TH. If the previous command value is smaller than the upper limit value TH in step S8 (YES in step S8), the process proceeds to step S10. If the previous command value is equal to or greater than the upper limit value TH in step S8 (NO in step S8), the process proceeds to step S12.

[0067] In step S12, the control device 60 sets the current command value to the upper limit value TH. This allows the control device 60 to prevent an overcurrent from flowing through the engine 11.

[0068] Furthermore, in step S10, the control device 60 sets the current command value to the same value as the previous command value, thereby suppressing fluctuations in the command torque value, as will be described with reference to FIG.

[0069] After the processes of steps S10, S12, and S114 are completed, the process proceeds to step S16. In step S16, the control device 60 stores the current command value set in any one of steps S10, S12, and S114. In the next command value setting process, the control device 60 uses the current command value stored in step S16 as the previous command value.

[0070] Furthermore, the order of the processes in Fig. 7 is not limited to the order shown in Fig. 7, and other orders may be used. For example, the process of step S8 may be executed before the process of step S6. Furthermore, by summarizing the processes in Fig. 7, the current command value is expressed by the following equation (1).

[0071] Current command value = Min(TH, Max(TL, previous command value)) (1) In the formula (1), the function Max(p, q) is a function that outputs the larger of the real numbers p and q, and the function Min(p, q) is a function that outputs the smaller of the real numbers p and q. [Simulation Results] Figure 8 shows an example of a simulation result of the motor control device 300 of this embodiment. The horizontal axis in Figures 8(A) to 8(D) represents time. The vertical axis in Figure 8(A) represents the MG rotation speed. The vertical axis in Figure 8(B) represents the command torque value. The vertical axis in Figure 8(C) represents the realized torque value. The vertical axis in Figure 8(D) represents the MG current value.

[0072] Fig. 8(A) is the same as Fig. 3(A). Also, as shown in Fig. 8(B), when a start request is made, the command torque value (current command value) is set to an initial value S1. The initial value S1 is a value that is greater than a predetermined lower limit value and less than a predetermined upper limit value.

[0073] Furthermore, as explained in step S10, if the previous command value is greater than the lower limit TL and less than the upper limit TH, the control device 60 sets the current command value to the same value as the previous command value. Therefore, as shown in Fig. 8(B), the motor control device 300 can form a horizontal portion S3 for the command torque value.

[0074] Furthermore, as explained in step S14, when the previous command value is equal to or less than the lower limit value TL, the control device 60 sets the current command value to the lower limit value TL. Therefore, the motor control device 300 can form a following portion S4 in which the command torque value follows the lower limit value TL.

[0075] Furthermore, as explained in step S12, when the previous command value is equal to or greater than the upper limit value TH, the control device 60 sets the current command value to the upper limit value TH. Therefore, the motor control device 300 can form a following portion S2 in which the command torque value follows the upper limit value TH.

[0076] 8(C), the realized torque value of this embodiment is shown by a solid line, the command torque value is shown by a dashed line, and the realized torque value of the comparative example is shown by a dashed line. Also, as described above, in this embodiment as well, the timing at which the command torque value is reflected as the realized torque value is later than the timing at which the command torque value is set.

[0077] 8B, in this embodiment, fluctuations in the command torque value are suppressed. Therefore, fluctuations in the realized torque value corresponding to the command torque value can be suppressed compared to the realized torque value in the comparative example.

[0078] 8(D), the MG current value at the coincidence timing t2 in the latter half of the starting phase of the MG 21 can be reduced. This is because, as described above, fluctuations in the command torque value are suppressed, which in turn suppresses fluctuations in the realized torque value. This prevents the MG current value from exceeding the overcurrent threshold.

[0079] As described above, the motor control device of the comparative example can have a problem in that the MG current flowing through the MG becomes excessive when the engine is started (see FIG. 3(D)). To solve this problem, a configuration can be considered in which the tension of the transmission belt 17 is increased to suppress pulsation in the MG rotation speed as shown in FIG. 3(A). However, this configuration increases torque loss and lengthens the time it takes for the engine 11 to stabilize, thereby reducing startability. Another possible solution to this problem is a configuration in which the command torque value shown in FIG. 3(B) is reduced. However, even with this configuration, it still takes longer for the engine 11 to stabilize, thereby reducing startability.

[0080] Therefore, when starting the MG 21, the motor control device 300 of this embodiment acquires the rotation speed detected by the rotation speed sensor 42 (step S2). Next, the motor control device 300 acquires the upper limit value and lower limit value associated with the acquired rotation speed based on the torque map (step S4). Next, if the previous command value is equal to or smaller than the lower limit value TL (NO in step S6), the motor control device 300 sets the current command value to the lower limit value TL (step S14). Furthermore, if the previous command value is equal to or larger than the upper limit value TH, the motor control device 300 sets the current command value to the upper limit value TH (step S12). Furthermore, if the previous command value is greater than the lower limit value TL and less than the upper limit value TH, the motor control device 300 sets the current command value to the same value as the previous command value (step S10).

[0081] With this configuration, as shown in Figure 8(B), the motor control device 300 can suppress fluctuations in the change in the command torque value over time. Therefore, for example, the command torque value can be reduced even at coincidence time t2 in the latter half of the starting period (the period when the MG rotation speed tends to increase). This makes it possible to reduce the MG current value at coincidence time t2, thereby preventing the motor current flowing through the MG 21 from becoming excessive when the MG 21 is started.

[0082] 5 is a value that is determined in advance based on the suppression of overcurrent to MG 21. Therefore, motor control device 300 can prevent the motor torque command value from exceeding the upper limit, which is a value based on the suppression of overcurrent to MG 21. Therefore, it is possible to prevent the motor current flowing through MG 21 from becoming excessive when the engine is started.

[0083] 5 is a value that is determined in advance based on whether or not the engine is prevented from stopping. Therefore, motor control device 300 can prevent the MG torque command value from falling below the lower limit, which is a value based on which the engine is prevented from stopping. Therefore, engine 11 can be prevented from stopping when MG 21 is started.

[0084] Furthermore, torque map 65 is defined so that the higher the motor rotation speed, the smaller the upper and lower limit values. Therefore, when the rotation speed of MG 21 increases, the torque command value can be reduced. As a result, motor control device 300 can start engine 11 and MG 21 appropriately. [Other embodiments] (1) In the example of Figure 7 described above, motor control device 300 is configured to set the current command value to the previous command value when the previous command value is greater than the lower limit and less than the upper limit. However, motor control device 300 may be configured to set the current command value to the previous command value when the previous command value is greater than or equal to the lower limit and less than the upper limit. If such a configuration is used, then if the previous command value is the same as lower limit TL in step S6, a determination of YES is made in step S6.

[0085] Alternatively, motor control device 300 may be configured to set the current command value to the previous command value when the previous command value is greater than the lower limit and less than or equal to the upper limit. If such a configuration is employed, then if the previous command value is equal to upper limit TH in step S8, a determination of YES is made in step S8.

[0086] Alternatively, the motor control device 300 may be configured to set the current command value to the previous command value when the previous command value is equal to or greater than the lower limit value and equal to or less than the upper limit value. If such a configuration is employed, then if the previous command value is equal to the lower limit value TL in step S6, then a YES determination is made in step S6. Also, if the previous command value is equal to the upper limit value TH in step S8, then a YES determination is made in step S8.

[0087] (2) In the above embodiment, the command value information is the torque map 65. However, the command value information may be any information that is an upper limit value and a lower limit value associated with the rotation speed of the MG 21. For example, the command value information may be information (e.g., a function) that receives the rotation speed as an input and outputs an upper limit value and a lower limit value.

[0088] (3) In the above embodiment, the high-voltage battery 23 is described as being 48 V. However, the voltage value of the battery used may be other values. For example, it may be 12 V or 24 V. In such a configuration, the starter 19 starts the engine 11.

[0089] (4) In the above embodiment, the member wound around the first pulley 16 and the second pulley 18 is the transmission belt 17. However, this member may be any other flexible member. For example, this member may be a chain. Furthermore, the number of transmission belts 17 is not limited to one, and may be two or more.

[0090] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The scope of the present disclosure is defined by the claims, not by the description of the above embodiments, and is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0091] 1 Hybrid vehicle, 11 Engine, 11A Crankshaft, 12 Transmission, 13 Cylinder, 15 Fuel injection valve, 16 First pulley, 17 Transmission belt, 18 Second pulley, 19 Starter, 21A Rotating shaft, 22 Inverter, 23 High voltage battery, 25 Converter, 26 Low voltage battery, 27 Auxiliary equipment, 28 Battery management system, 30 Drive wheel, 31 Belt tensioner, 41 Crank angle sensor, 42 Rotational speed sensor, 43 Motor current sensor, 60 Control device, 61 Storage device, 65 Torque map, 102 Acquisition unit, 104 Command unit, 300 Motor control device.

Claims

1. a motor connected to the engine so that power can be transmitted between them; a control device that periodically sets a torque command value for the motor; a sensor for detecting the rotation speed of the motor; a storage device that stores command value information in which an upper limit value of the command value and a lower limit value of the command value are defined in association with a rotation speed of the motor, The control device When starting the engine with the motor, the rotation speed detected by the sensor is acquired; acquiring the upper limit value and the lower limit value associated with the acquired rotation speed based on the command value information; If the previous command value set previously is smaller than the lower limit value, the current command value is set to the lower limit value; If the previous command value is greater than the upper limit value, the current command value is set to the upper limit value; When the previous command value is greater than the lower limit value and smaller than the upper limit value, the current command value is set to the same value as the previous command value.

2. The motor control device according to claim 1 , wherein the upper limit value is a value determined based on suppression of an overcurrent to the motor.

3. 3. The motor control device according to claim 1, wherein the lower limit value is a value determined based on the fact that stopping of the engine is suppressed.

4. 3. The motor control device according to claim 1, wherein the command value information is defined such that the upper limit value and the lower limit value become smaller as the rotation speed increases.

5. A motor control method for a motor connected to an engine so that power can be transmitted between the engine and the motor, comprising: the motor control method includes periodically setting a torque command value of the motor; Setting the command value includes: acquiring a rotational speed of the motor when starting the engine with the motor; obtaining an upper limit value and a lower limit value associated with the obtained rotation speed; If a previous command value that was set previously is smaller than the lower limit value, setting the current command value to the lower limit value; If the previous command value is greater than the upper limit value, setting the current command value to the upper limit value; a current command value set to the same value as the previous command value when the previous command value is greater than the lower limit value and less than the upper limit value.

Images