Hybrid vehicle control device

Abstract

To provide a control device of a hybrid vehicle that can protect a switching element from a rapid temperature rise, even if vehicle speed rapidly decreases.SOLUTION: A control device of a hybrid vehicle is equipped with an engine 2, a motor 4, an inverter 5 that supplies alternating-current power to the motor 4 by using a switching element, a rotation sensor 41 that detects the rotation speed of the motor 4, and a control portion 6 that restricts the torque of the motor 4 when it is detected that the rotation speed of the motor 4 decreases by a predetermined rate of change or more.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a control device for a hybrid vehicle. [Background technology]

[0002] Patent Document 1 discloses a technique in which, when the motor becomes locked while climbing a slope, the torque of the motor is reduced to release the locked state and prevent damage to the switching elements. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 11-215687 Summary of the Invention [Problem to be solved by the invention]

[0004] In Patent Document 1, it is determined that the motor is in a locked state when the motor rotation speed is lower than a first predetermined motor rotation speed and the motor torque command value is greater than a predetermined torque value.

[0005] However, when the motor torque command value is high and the vehicle suddenly decelerates, causing the motor rotational speed to decrease and motor lock to be detected, the temperature of the switching elements will rise rapidly, and there is a risk that torque reduction control will not be able to keep up.

[0006] SUMMARY OF THE PRESENT DISCLOSURE In view of the above, an object of the present invention is to provide a control device for a hybrid vehicle that can protect switching elements from a sudden increase in temperature even when the vehicle speed is suddenly reduced. [Means for solving the problem]

[0007] In order to solve the above problems, the present invention provides a control device for a hybrid vehicle including an engine, a motor, an inverter that uses switching elements to supply AC power to the motor, and a rotation speed detection unit that detects a rotation speed of the motor, The motor control unit includes a first filter and a second filter for correcting the rotation speed, and calculates a motor rotation speed change amount that is an absolute value of a difference between a correction value by the first filter and a correction value by the second filter, the second filter having a lower responsiveness than the first filter, and when the correction value by the first filter is equal to or lower than a predetermined rotation speed and the torque of the motor is equal to or higher than a predetermined motor torque, the control unit starts to determine whether the motor rotation speed change amount is equal to or higher than a predetermined value, and continues to determine that the motor rotation speed change amount is equal to or higher than the predetermined value for a predetermined time. In this case, the torque of the motor is limited. Rumo That is why. Effect of the Invention

[0008] In this way, according to the present invention, even if the vehicle speed is suddenly reduced, the switching element can be protected from a sudden increase in temperature. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a schematic diagram of a hybrid vehicle according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a flowchart showing a procedure of a motor output control process of the control device for a hybrid vehicle according to one embodiment of the present invention. [Diagram 3] FIG. 3 is a time chart showing a change in rotation speed that is filtered by the motor output control process of the control device for a hybrid vehicle according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] A control device for a hybrid vehicle according to one embodiment of the present invention is a control device for a hybrid vehicle that includes an engine, a motor, an inverter that supplies AC power to the motor using switching elements, and a rotational speed detection unit that detects the rotational speed of the motor, and is configured to include a control unit that limits the torque of the motor when it detects that the rotational speed of the motor has decreased by more than a predetermined rate of change.

[0011] As a result, the control device for a hybrid vehicle according to one embodiment of the present invention can protect the switching elements from a sudden increase in temperature even when the vehicle speed is suddenly reduced. EXAMPLES

[0012] A hybrid vehicle equipped with a control device according to an embodiment of the present invention will be described in detail below with reference to the drawings.

[0013] In FIG. 1, a hybrid vehicle 1 according to an embodiment of the present invention includes an engine 2, a transmission 3, a motor 4, an inverter 5, and a control unit 6.

[0014] A plurality of cylinders are formed in the engine 2. In this embodiment, the engine 2 is configured to perform a series of four strokes, which are an intake stroke, a compression stroke, an expansion stroke, and an exhaust stroke, for each cylinder.

[0015] The transmission 3 changes the speed of the rotation output from the engine 2 and drives left and right drive wheels 8 via a differential 7. The transmission 3 includes a constant mesh type speed change mechanism (not shown) made of a parallel shaft gear mechanism, and an actuator (not shown).

[0016] A dry single-plate clutch 31 is provided between the engine 2 and the transmission 3, and the clutch 31 connects and disconnects the power transmission between the engine 2 and the transmission 3.

[0017] The transmission 3 is configured as a so-called AMT (Automated Manual Transmission), and an actuator (not shown) switches the gear positions in the speed change mechanism and engages and disengages the clutch 31.

[0018] The motor 4 has a function as an electric motor driven by power supplied from a battery (not shown) via an inverter 5, and a function as a generator that performs regenerative power generation by a reverse driving force input from a differential 7. The output shaft of the motor 4 is connected to the output shaft of the transmission 3.

[0019] The motor 4 is provided with a rotation sensor 41 serving as a rotation speed detection unit that detects the rotation speed of the motor 4. The rotation sensor 41 is connected to the control unit 6.

[0020] Under the control of the control unit 6, the inverter 5 converts the DC power supplied from the battery into three-phase AC power and supplies it to the motor 4, or converts the three-phase AC power generated by the motor 4 into DC power to charge the battery.

[0021] The inverter 5 includes, for example, six switching elements, and controls the three-phase AC power supplied to the motor 4 by controlling the six switching elements.

[0022] The inverter 5 is provided with a current sensor 51 that detects a current supplied from the inverter 5 to the motor 4. The current sensor 51 is connected to the control unit 6.

[0023] The control unit 6 is composed of a computer unit equipped with a CPU (Central Processing Unit), a RAM (Random Access Memory), a ROM (Read Only Memory), a flash memory for storing backup data, etc., an input port, and an output port.

[0024] The ROM of this computer unit stores various constants, various maps, and the like, as well as a program for causing the computer unit to function as the control unit 6.

[0025] That is, the CPU executes the programs stored in the ROM using the RAM as a working area, and these computer units function as the control unit 6 in this embodiment.

[0026] To the input port of the control unit 6, various sensors including the rotation sensor 41 and the current sensor 51 described above are connected.

[0027] On the other hand, an output port of the control unit 6 is connected to various control targets including the inverter 5 and the actuator of the transmission 3, as well as an injector (not shown).

[0028] In this embodiment, when the control unit 6 detects that the rotation speed of the motor 4 has decreased by a predetermined rate of change or more, the control unit 6 limits the torque of the motor 4. Limiting the torque of the motor 4 means, for example, lowering the upper limit value of the motor torque.

[0029] The control unit 6 has, for example, a filter that corrects the rotation speed of the motor 4, and limits the torque of the motor 4 when the difference between the rotation speed of the motor 4 and the value obtained by correcting the rotation speed of the motor 4 using the filter is greater than or equal to a predetermined value.

[0030] The control unit 6, for example, has a first filter and a second filter having lower responsiveness than the first filter, and limits the torque of the motor 4 when the motor rotation speed change amount, which is the difference between the value corrected by the first filter and the value corrected by the second filter, is equal to or greater than a predetermined judgment threshold.

[0031] The first filter and the second filter have different cutoff frequencies. For example, the first filter has a higher cutoff frequency and a smaller time constant.

[0032] For example, the first filter is a filter that changes at approximately the same speed as the angle sensor used for motor torque control, and is used for motor lock determination and the like.

[0033] For example, when a predetermined determination condition is met, the control unit 6 determines whether or not the motor rotation speed change amount is equal to or greater than the determination threshold value.

[0034] The judgment conditions are, for example, that the rotation speed of the motor 4 is equal to or lower than a predetermined motor rotation speed, and that the torque of the motor 4 is equal to or higher than a predetermined motor torque.

[0035] The control unit 6 limits the torque of the motor 4, for example, when a predetermined determination condition is met and a state in which the amount of change in the motor rotation speed is equal to or greater than the determination threshold continues for a predetermined period of time.

[0036] The control unit 6 releases the torque limit of the motor 4, for example, when a predetermined return condition is met.

[0037] The return condition may be, for example, that any one or any combination of the following is satisfied: the rotational speed of motor 4 is equal to or greater than a predetermined return rotational speed, the torque of motor 4 is equal to or less than a predetermined return torque, the amount of change in motor rotational speed is equal to or less than a predetermined return threshold value, etc.

[0038] The motor output control process performed by the control device for a hybrid vehicle according to this embodiment configured as above will be described with reference to Fig. 2. The motor output control process described below is started when the control unit 6 starts its operation, and is executed at preset time intervals.

[0039] In step S1, the control unit 6 performs filtering using two filters having different responsiveness on the rotation speed of the motor 4. After executing the processing of step S1, the control unit 6 executes the processing of step S2.

[0040] In step S2, the control unit 6 calculates, as the motor rotation speed change amount, the absolute value of the value obtained by subtracting the rotation speed value of the motor 4 filtered by the fast response filter from the rotation speed value of the motor 4 filtered by the slow response filter. After executing the process of step S2, the control unit 6 executes the process of step S3.

[0041] By taking the absolute value of the difference between the filter values, the amount of change in motor rotation speed can be correctly calculated even when the motor 4 changes from forward rotation to reverse rotation or from reverse rotation to forward rotation, and it can handle both increasing and decreasing directions of the motor rotation speed. Therefore, it can also handle sudden changes in motor rotation speed when the tires lock or wheels spin, which occur due to the system structure.

[0042] In step S3, the control unit 6 determines whether or not the above-mentioned determination condition is met. If it is determined that the determination condition is met, the control unit 6 executes the process of step S4.

[0043] If it is determined that the determination condition is not satisfied, the control unit 6 executes the process of step S1.

[0044] In step S4, the control unit 6 determines whether the motor rotation speed change amount has been equal to or greater than the determination threshold for a predetermined time. If it is determined that the motor rotation speed change amount has been equal to or greater than the determination threshold for a predetermined time, the control unit 6 executes the process of step S6.

[0045] When it is determined that the amount of change in motor rotation speed has not been equal to or greater than the determination threshold for the predetermined time, the control unit 6 executes the process of step S5.

[0046] In step S5, the control unit 6 performs normal processing to control the motor 4. After executing the processing of step S5, the control unit 6 ends the motor output control processing.

[0047] In step S6, the control unit 6 performs an output limiting process to control the motor 4. After executing the process of step S6, the control unit 6 ends the motor output control process.

[0048] The operation of such a motor output control process will be described with reference to FIG. At time t1, the rotational speed of motor 4 filtered by the fast-response filter becomes equal to or lower than the rotational speed of the judgment condition, and the torque of motor 4 is equal to or higher than the torque of the judgment condition, so that the judgment condition is met and judgment of the amount of change in the motor rotational speed begins.

[0049] At time t2, the amount of change in motor rotation speed becomes equal to or greater than the determination threshold, and at time t3, the state in which the amount of change in motor rotation speed is equal to or greater than the determination threshold continues for the determination time, so that the output of motor 4 is limited.

[0050] In this manner, in this embodiment, the control unit 6 limits the torque of the motor 4 when it detects that the rotation speed of the motor 4 has decreased by a predetermined rate of change or more.

[0051] When it is detected that the rotation speed of the motor 4 is decreasing by more than a predetermined rate of change, there is a high possibility that the rotation speed of the motor 4 will then enter a low rotation range, increasing the possibility of motor lock occurring.

[0052] Therefore, by predicting the motor lock and reducing the torque of the motor 4, it is possible to prevent the motor from locking up, and to protect the switching elements of the inverter 5 from a sudden increase in temperature.

[0053] In addition, the control unit 6 has a filter that corrects the rotation speed of the motor 4, and limits the torque of the motor 4 when the difference between the rotation speed of the motor 4 and the value obtained by correcting the rotation speed of the motor 4 using the filter is greater than or equal to a predetermined value.

[0054] If the change in the rotation speed of the motor 4 is used for the judgment as it is, there is a possibility that an erroneous judgment may occur. The value obtained by correcting the rotation speed of the motor 4 using a filter does not differ greatly from the rotation speed of the motor 4 during normal driving, but if there is a sudden change, the difference becomes large.

[0055] By using this characteristic, the torque of motor 4 is limited when there is a large difference between the rotation speed of motor 4 and the value obtained by correcting the rotation speed of motor 4 using a filter, making it possible to prevent erroneous judgments and protect the switching elements from a sudden increase in temperature.

[0056] The control unit 6 also has a first filter and a second filter having a lower responsiveness than the first filter, and limits the torque of the motor 4 when a change in motor rotation speed, which is the difference between the value corrected by the first filter and the value corrected by the second filter, is equal to or greater than a predetermined judgment threshold.

[0057] While there is no significant difference between the values ​​of the two filters during normal driving, if the rotation speed of the motor 4 changes suddenly, there will be a significant difference between the values ​​of the two filters.

[0058] Therefore, by determining whether the difference between the values ​​corrected by the two filters is equal to or greater than a predetermined value, it is possible to predict that the rotation speed of motor 4 will enter the low rotation range and reduce the torque of motor 4, thereby protecting the switching elements from a sudden increase in temperature.

[0059] For example, the first filter is a filter that changes at approximately the same speed as the angle sensor used for motor torque control, and is used for motor lock determination, etc. Sudden deceleration can be detected by the first filter alone, but since the value changes rapidly, there will be many erroneous determinations, so erroneous determinations are prevented by using the difference between the two filters.

[0060] In this embodiment, an example has been described in which the control unit 6 performs various determinations and calculations based on various sensor information, but this is not limited thereto. The hybrid vehicle 1 may be provided with a communication unit capable of communicating with an external device such as an external server, and various determinations and calculations may be performed by the external device based on the detection information of the various sensors transmitted from the communication unit. The determination results and calculation results may be received by the communication unit, and various controls may be performed using the received determination results and calculation results.

[0061] Although an embodiment of the invention has been disclosed, it will be apparent to one of ordinary skill in the art that modifications may be made thereto without departing from the spirit and scope of the invention, and it is intended that all such modifications and equivalents be included in the following claims. [Explanation of symbols]

[0062] 1 Hybrid vehicles 2 Engine 4 Motors 5. Inverter 6. Control Unit 41 Rotation sensor (rotation speed detection section) 51 Current Sensor

Claims

[Claim 1] A control device for a hybrid vehicle including an engine, a motor, an inverter that uses a switching element to supply AC power to the motor, and a rotation speed detection unit that detects a rotation speed of the motor, a control unit having first and second filters for correcting the rotation speed, and calculating a motor rotation speed change amount that is an absolute value of a difference between a correction value by the first filter and a correction value by the second filter; the second filter being less responsive than the first filter; A control device for a hybrid vehicle, wherein the control unit starts determining whether the motor rotational speed change amount is greater than or equal to a predetermined value when the correction value by the first filter is less than or equal to a predetermined rotational speed and the torque of the motor is greater than or equal to a predetermined motor torque, and limits the torque of the motor when it continues to determine that the motor rotational speed change amount is greater than or equal to the predetermined value for a predetermined time.

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