JP2004120946A - Motor drive unit - Google Patents

Abstract

An electric motor driving device includes: a pair of semiconductor switches connected in parallel to an electric motor; and a control unit that outputs a drive signal for simultaneously turning on and off the two semiconductor switches during normal operation of the electric motor. In the above, the time for determining the abnormality of the two semiconductor switches is shortened, and the generation of operation noise due to the operation of the electric motor for detecting the abnormality is suppressed to a very short time.
A control unit (30) outputs an ON signal for turning on one of a pair of semiconductor switches (25, 26) for a predetermined time by switching each time an ignition switch (27) is turned on, and a control unit on the side to which the ON signal is applied. An abnormality of the semiconductor switch is initially diagnosed based on an actual power supply state to the electric motor 11, and occurs between both ends of the parallel circuit 27 including the semiconductor switches 25 and 26 when the electric motor 11 is normally operated after the initial diagnosis. The abnormality of the parallel circuit 27 is diagnosed based on the potential difference.
[Selection] Fig. 2

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a pair of semiconductor switches connected in parallel to an electric motor mounted on a vehicle, and a control unit that outputs a drive signal for simultaneously turning on and off the two semiconductor switches during normal operation of the electric motor. More particularly, the present invention relates to an improvement in a configuration for diagnosing a failure of a semiconductor switch.
[0002]
[Prior art]
For example, in a vehicle brake fluid pressure control device equipped with an electric motor, when the electric motor is driven by PWM, a semiconductor switch such as a field-effect transistor connected to the electric motor generates heat, and further performance degradation or failure occurs. In some cases, a pair of the semiconductor switches is connected to an electric motor in order to suppress the above problem.
[0003]
[Problems to be solved by the invention]
Even when the pair of semiconductor switches is connected to the electric motor in parallel, it is necessary to diagnose the abnormality of each semiconductor switch. Is activated, the time for the abnormality diagnosis becomes uselessly long, and the operation noise of the electric motor becomes noticeable.
[0004]
The present invention has been made in view of such circumstances, and aims to reduce the time for determining an abnormality of a pair of semiconductor switches, and to reduce the generation of operation noise due to the operation of an electric motor for abnormality detection in a very short time. It is an object of the present invention to provide an electric motor drive device that can be suppressed.
[0005]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides a pair of semiconductor switches connected in parallel to an electric motor mounted on a vehicle, and a switch for simultaneously turning on and off the two semiconductor switches during normal operation of the electric motor. A control unit that outputs a drive signal, wherein the control unit outputs an ON signal that causes one of the pair of semiconductor switches to conduct for a predetermined time so as to switch each time the ignition switch is conducted. Initial diagnosis means for diagnosing an abnormality of the semiconductor switch on the side to which the ON signal is given based on the actual power supply state to the electric motor; and An abnormality in the parallel circuit is diagnosed based on a potential difference generated between both ends of the parallel circuit including the semiconductor switches. Characterized in that it comprises a normal diagnosis means.
[0006]
According to such a configuration, when the ignition switch is turned on to start the vehicle engine, an ON signal for turning ON one of the pair of semiconductor switches for a predetermined time is given. An abnormality of the assigned semiconductor switch can be diagnosed by the initial diagnosis means based on the actual power supply state to the electric motor. Also, during normal operation of the electric motor after completion of the diagnosis by the initial diagnosis means, if an abnormality has occurred in a semiconductor switch different from the semiconductor switch diagnosed in the initial diagnosis, only the semiconductor switch determined to be normal in the initial diagnosis is electrically operated. Since the current for driving the motor flows, the amount of heat generated by the normal semiconductor switch increases, and the resistance value of the normal semiconductor switch increases due to the increase in the amount of heat generated. The potential difference between both ends increases. Therefore, the abnormality of the semiconductor switch different from the semiconductor switch diagnosed as normal in the initial diagnosis can be diagnosed by the normal-time diagnosis means. Moreover, the semiconductor switch to be diagnosed by the initial diagnosis means is switched alternately each time the ignition switch is turned on, and is different from the semiconductor switch to be diagnosed by the initial diagnosis means during normal operation of the electric motor. The semiconductor switch is to be diagnosed, and it is possible to diagnose the abnormality of the pair of semiconductor switches simply by operating the electric motor for the diagnosis for a short time at the time of the initial diagnosis, and to diagnose the abnormality of the pair of semiconductor switches. Can be shortened, and the generation of operation noise due to the operation of the electric motor for abnormality detection can be suppressed in a very short time.
[0007]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of the present invention will be described based on an embodiment of the present invention shown in the attached drawings.
[0008]
1 to 8 show one embodiment of the present invention. FIG. 1 is a hydraulic circuit diagram of a vehicle brake device, FIG. 2 is a diagram showing a configuration of a driving device of an electric motor, and FIG. 3 is a control unit. 4 is a flowchart showing a procedure for determining an initial diagnosis target, FIG. 5 is a flowchart showing an initial diagnosis processing procedure, and FIG. 6 is a flowchart showing an initial diagnosis target every time the ignition is turned on. FIG. 7 is a timing chart for explaining a switching state, FIG. 7 is a flowchart showing a normal diagnosis processing procedure, and FIG. 8 is a diagram showing an example of a timing chart for a normal diagnosis after the initial diagnosis is completed.
[0009]
First, in FIG. 1, a tandem type master cylinder M is provided with first and second output ports 1A and 1B for generating a brake fluid pressure according to a depression force applied to a brake pedal P by a vehicle driver, and is used for a left front wheel. Wheel brake 2A, right rear wheel brake 2B, right front wheel brake 2C, left rear wheel brake 2D, and first and second individually connected to the first and second output ports 1A, 1B. A brake hydraulic pressure control device 4 is provided between the output hydraulic pressure passages 3A and 3B.
[0010]
The brake fluid pressure control device 4 includes a fluid pressure passage 20A corresponding to the first output fluid pressure passage 3A and normally open solenoid valves 6A, 6B provided between the left front wheel brake 2A and the right rear wheel brake 2B, respectively. A normally open solenoid valve 6C, 6D provided between the right front wheel brake 2C and the left rear wheel brake 2D, and a hydraulic passage 20B corresponding to the second output hydraulic passage 3B. Check valves 7A, 7B, 7C, 7D connected in parallel to the normally-open solenoid valves 6A to 6D so as to allow the flow of the brake fluid to the side of the first and second output hydraulic pressure paths. Normally closed first and second reservoirs 8A and 8B respectively corresponding to 3A and 3B, and a normally closed state provided between the first reservoir 8A and the left front wheel brake 2A and the right rear wheel brake 2B, respectively. Solenoid valves 9A and 9B, second reservoir 8B, normally closed solenoid valves 9C and 9D provided between right front wheel brake 2C and left rear wheel brake 2D, and first and second reservoirs 8A and 8B. A first and second pumps 10A and 10B having a suction portion connected to the fluid passages 20A and 20B and a common electric motor 11 for driving both pumps 10A and 10B; Normally closed solenoid valves 12A and 12B interposed between the first and second output hydraulic paths 3A and 3B and the suction portions of the first and second pumps 10A and 10B, respectively, and the first and second pumps 10A and 10B. And first and second pumps 10A and 10B, and first and second dampers 13A and 13B interposed between the discharge section and the hydraulic paths 20A and 20B, respectively. The first and second pumps 10A, 10B and the first and second orifices 14A, 14B are respectively provided between the second dampers 13A, 13B and the first and second pumps 10A, 10B so as to allow the flow of brake fluid to the pumps 10A, 10B. Check valves 15A and 15B interposed between the first and second reservoirs 8A and 8B, a pressure sensor 16 attached to the second output hydraulic pressure passage 3B, the first and second output hydraulic pressure passages 3A and 3B, and the fluid. Regulators 21A and 21B are provided between the pressure paths 20A and 20B, respectively.
[0011]
The normally closed solenoid valves 12A and 12B are provided between the first and second pumps 10A and 10B and the check valves 15A and 15B and between the output hydraulic pressure paths 3A and 3B, respectively.
[0012]
The regulators 21A and 21B include normally open solenoid valves 5A and 5B, one-way valves 18A and 18B, and relief valves 19A and 19A between the first and second output hydraulic paths 3A and 3B and the hydraulic paths 20A and 20B. 19B are connected in parallel.
[0013]
The one-way valves 18A and 18B are connected in parallel to the normally-open solenoid valves 5A and 5B so as to allow the flow of the brake fluid only from the first and second output hydraulic paths 3A and 3B. The relief valves 19A and 19B are connected in parallel to the normally-open solenoid valves 5A and 5B so as to open when the hydraulic pressure of the hydraulic pressure paths 20A and 20B becomes equal to or higher than a predetermined value.
[0014]
Although such regulators 21A and 21B always communicate between the first and second output hydraulic passages 3A and 3B and the hydraulic passages 20A and 20B that communicate with the master cylinder M, the regulators 21A and 21B have the normally closed solenoid valves 12A and 12B. When the valve is opened, the output hydraulic pressure passages 3A, 3B and the hydraulic pressure passages 20A, 20B are shut off while the hydraulic pressures of the hydraulic pressure passages 20A, 20B become higher than a set value while being shut off. It operates to release the hydraulic pressure to the master cylinder M side, thereby adjusting the hydraulic pressure of the hydraulic pressure paths 20A and 20B to a set value or less.
[0015]
The pressure sensor 16 detects whether or not the hydraulic pressure is output from the master cylinder M, that is, whether or not the brake pedal P is depressed. It is used for controlling the number of revolutions of the electric motor 11 according to the output hydraulic pressure of M, and the like.
[0016]
By the way, in the above-mentioned brake fluid pressure control device 4, at the time of normal braking in which each wheel is unlikely to be locked, the normally-open solenoid valves 5A and 5B are demagnetized and opened, and the normally-closed solenoid valves 12A and 12B are demagnetized. In the closed state, the normally-open solenoid valves 6A to 6D are demagnetized and opened, and the normally-closed solenoid valves 9A to 9D are demagnetized and closed. As a result, communication is established between the master cylinder M and the wheel brakes 2A to 2D, and between the wheel brakes 2A to 2D and the reservoirs 8A and 8B. Accordingly, the brake fluid pressure output from the first output port 1A of the master cylinder M acts on the left front wheel and right rear wheel brakes 2A, 2B via the normally-open solenoid valve 5A and the normally-open solenoid valves 6A, 6B. I do. The brake fluid pressure output from the second output port 1B of the master cylinder M is supplied to the right front wheel and left rear wheel brakes 2C, 2D via the normally-open solenoid valve 5B and the normally-open solenoid valves 6C, 6D. Act on.
[0017]
When the wheels are about to enter the locked state during the braking, the normally open solenoid valves corresponding to the wheels that are about to enter the locked state among the normally opened solenoid valves 6A to 6D are excited and closed. At the same time, the normally closed solenoid valves corresponding to the wheels among the normally closed solenoid valves 9A to 9D are excited and opened. As a result, the master cylinder M and the wheel brakes 2A to 2D are cut off at the portion corresponding to the wheel that is about to enter the locked state, and the wheel brakes 2A to 2D and the reservoirs 8A and 8B are communicated. Therefore, a part of the brake fluid pressure of the wheel about to enter the locked state is absorbed by the first reservoir 8A or the second reservoir 8B, and the brake fluid pressure of the wheel about to enter the locked state is reduced. Become.
[0018]
When the brake fluid pressure is kept constant, the normally-open solenoid valves 6A to 6D are energized and closed, and the normally-closed solenoid valves 9A to 9D are demagnetized and closed. 2D are disconnected from master cylinder M and reservoirs 8A and 8B.
[0019]
When the brake fluid pressure is further increased, the normally open solenoid valves 6A to 6D are demagnetized and opened, and the normally closed solenoid valves 9A to 9D are demagnetized and closed. The cylinder M and the wheel brakes 2A to 2D communicate with each other, and the wheel brakes 2A to 2D and the reservoirs 8A and 8B are shut off.
[0020]
With the normally-open solenoid valves 5A and 5B demagnetized and opened, and the normally-closed solenoid valves 12A and 12B demagnetized and closed, the normally-open solenoid valves 6A to 6D and the normally-closed solenoid valves 5A and 5B are closed. By controlling the demagnetization / excitation of the valves 9A to 9D, braking can be efficiently performed without locking the wheels.
[0021]
By the way, during the above-described antilock brake control, the electric motor 11 rotates and the first and second pumps 10A and 10B are driven by the operation of the electric motor 11, so that the first and second pumps are driven. The brake fluid absorbed by the reservoirs 8A, 8B is sucked into the first and second pumps 10A, 10B, and then passes through the first and second dampers 13A, 13B to the first and second output hydraulic lines 3A, 3B. It is refluxed. By such a return of the brake fluid, it is possible to prevent an increase in the amount of depression of the brake pedal P due to the absorption of the brake fluid in the first and second reservoirs 8A and 8B. Moreover, the pulsation of the discharge pressure of the first and second pumps 10A and 10B is suppressed by the functions of the first and second dampers 13A and 13B and the first and second orifices 14A and 14B. The ring is not disturbed.
[0022]
Further, the brake fluid pressure control device 4 can perform a side slip control and a traction control of the vehicle in a non-braking operation state in addition to the above-described antilock brake control.
[0023]
Thus, for example, during side slip control, the normally open solenoid valves 5A and 5B of the regulators 21A and 21B are excited and closed, and the normally closed solenoid valves 12A and 12B are excited and opened. , The first and second pumps 10A and 10B are driven, and the normally-open solenoid valves other than the normally-open solenoid valve corresponding to the wheel to be braked among the normally-open solenoid valves 6A to 6D are excited and closed. .
[0024]
Thereby, both pumps 10A and 10B transfer the brake fluid of the master cylinder M from the first and second output ports 1A and 1B through the first and second output hydraulic pressure paths 3A and 3B and the normally closed solenoid valves 12A and 12B. The brake fluid is supplied to the selected one of the wheel brakes 2A to 2D via the normally open solenoid valve that is open among the normally open solenoid valves 6A to 6D. Is prevented from flowing back to the master cylinder M side because the normally open solenoid valves 5A and 5B are closed.
[0025]
During such side slip control or traction control, when the hydraulic pressure of the hydraulic passages 20A, 20B on which the hydraulic pressures discharged from the first and second pumps 10A, 10B act becomes equal to or higher than a set value, the relief valves of the regulators 21A, 21B. By 19A and 19B, the excess hydraulic pressure is released to the master cylinder M side, thereby preventing the excessive hydraulic pressure from acting on the wheel brake on which the brake pressure is applied.
[0026]
Moreover, since the dampers 13A and 13B are interposed between the hydraulic paths 20A and 20B and the orifices 14A and 14B, the pulsations generated in the hydraulic paths 20A and 20B by the operation of the regulators 21A and 21B are absorbed by the dampers 13A and 13B. Therefore, it is possible to suppress the generation of the operation noise caused by the pulsation due to the operation of the regulators 21A and 21B.
[0027]
In FIG. 2, the electric motor 11 is connected to a parallel circuit 27 formed by connecting first and second field effect transistors (FETs) 25 and 26 as a pair of semiconductor switches in parallel. The parallel circuit 27 is connected to a vehicle-mounted battery 29 via an ignition switch 28.
[0028]
The ON / OFF of the first and second FETs 25 and 26 is controlled by the control unit 30. When the electric motor 11 is normally operated, the control unit 30 drives the first and second FETs 25 and 26 so that the electric motor 11 is driven by PWM. 26 is output at the same time.
[0029]
In addition, the control unit 30 outputs an ON signal for turning on one of the first and second FETs 25 and 26 for a predetermined time by switching each time the ignition switch 28 is turned on, and the abnormality of the FET to which the ON signal is given. Based on the actual state of power supply to the electric motor 11 based on the potential difference generated between both ends of the parallel circuit 27 during normal operation of the electric motor 11 after completion of the diagnosis by the initial diagnosis unit. A normal diagnosis means for diagnosing abnormality of the parallel circuit 27 is provided. A signal corresponding to the conduction of the ignition switch 28 and a potential difference generated between both ends of the parallel circuit 27 are input to the control unit 30.
[0030]
The control unit 30 diagnoses the abnormality of both the FETs 25 and 26 in accordance with the procedure shown in FIG. 3. In step S1, it is determined whether or not the initial diagnosis has been completed. In step S1, the initial diagnosis is executed by the initial diagnosis means. When it is determined in step S1 that the initial diagnosis has been completed, the normal diagnosis is executed in step S3.
[0031]
Incidentally, which of the first and second FETs 25 and 26 is to be subjected to the initial diagnosis is determined by executing the process shown in FIG. 4 every time the ignition switch 28 is turned on, and the initial diagnosis target determination index MTRDRVCT Is defined as [MTRDRVCT (n) = MTRDRVCT (n-1) +1]. That is, the initial diagnosis target determination index MTRDRVCT is incremented by [1] every time the ignition switch 28 is turned on.
[0032]
The initial diagnosis in step S2 is executed by the initial diagnosis means in accordance with the subroutine shown in FIG. 5. In step S11, it is determined whether the current initial diagnosis target determination index MTRDRVCT (n) is an even number or an odd number. If it is determined that the number is an odd number, the first FET 25 is selected, and a signal for driving the first FET 25 for a predetermined time is output in step S12. If it is determined in step S12 that the current initial diagnosis target determination index MTRDRVCT (n) is an even number, the second FET 26 is selected, and a signal for driving the second FET 26 for a predetermined time is output in step S13.
[0033]
That is, as shown in FIG. 6, each time the ignition switch 28 is turned on, the initial diagnosis target determination index MTRDRVCT alternately becomes an odd number and an even number. The signal is output from the initial diagnosis unit of the control unit 30. When the signal is an even number, a signal for driving the second FET 26 for a predetermined time T is output from the initial diagnosis unit of the control unit 30.
[0034]
After the processing in step S12 or step S13 is completed, the process proceeds to step S14 to determine whether the FET to be diagnosed is normal or abnormal. An abnormality determination is made based on the fact that normal power is not supplied to the motor 11.
[0035]
The normal time diagnosis in step S3 is executed by the normal time diagnosis means in accordance with a subroutine shown in FIG. 7, and in step S21, it is determined whether or not the electric motor 11 is being driven. When it is determined, the process proceeds to step S22 to determine whether or not the potential difference generated between both ends of the parallel circuit 27 is large. When the potential difference is small, it is determined in step S23 that the FET to be subjected to the normal diagnosis is normal, When the potential difference is large, it is determined in step S24 that the FET that is the target of the normal diagnosis is abnormal.
[0036]
That is, as shown in FIG. 8, at the time of normal diagnosis after determining that the first FET 25 is normal in the initial diagnosis with the first FET 25 as a diagnosis target, an ON signal for simultaneously conducting the first and second FETs 25 and 26 is output. At the time of output, if the second FET 26 is abnormal, the second FET 26, which should be conducting as shown by the chain line if normal, remains off as shown by the solid line, so that only the first normal FET 25 is normal. A current for driving the electric motor 11 flows, and the amount of heat generated by the first FET 25 increases to increase the resistance value, thereby causing a potential difference generated between both ends of the parallel circuit 27 including the first and second FETs 25 and 26. That the potential difference has increased, and that the first FET 25 is determined to be normal in the initial diagnosis. Based on, it can be determined that the 2FET26 is abnormal.
[0037]
Next, the operation of this embodiment will be described. During normal operation of the electric motor 11, the control unit 30, which outputs a drive signal for simultaneously turning on and off the first and second FETs 25 and 26, is turned on every time the ignition switch 28 is turned on. And outputs an ON signal for turning on one of the first and second FETs 25 and 26 for a predetermined time. The abnormality of the FET to which the ON signal is applied is determined based on the actual power supply state to the electric motor 11. Initial diagnosis means for diagnosing the parallel circuit 27 based on a potential difference generated between both ends of the parallel circuit 27 comprising the first and second FETs 25 and 26 during normal operation of the electric motor after completion of the diagnosis by the initial diagnosis means. Normal diagnosis means for diagnosing abnormality.
[0038]
Therefore, when the ignition switch 28 is turned on in order to start the vehicle engine, an ON signal for turning on one of the first and second FETs 25 and 26 for a predetermined time is given, so that the ON signal is given. The abnormality of the FET on the side can be diagnosed by the initial diagnosis means based on the actual power supply state to the electric motor 11. Also, during normal operation of the electric motor 11 after completion of the diagnosis by the initial diagnosis means, if an abnormality occurs in a FET different from the FET diagnosed in the initial diagnosis, only the FET determined to be normal in the initial diagnosis is used. , The amount of heat generated by the normal FET increases, and the resistance value of the normal FET rises due to the increase in the amount of heat generated. The potential difference between them increases. Therefore, an abnormality of the FET different from the FET diagnosed as normal in the initial diagnosis can be diagnosed by the normal-time diagnosis means.
[0039]
In addition, the FET to be diagnosed by the initial diagnosis means is alternately switched every time the ignition switch 28 is turned on, and is different from the FET to be diagnosed by the initial diagnosis means during the normal operation of the electric motor 11. The FET is an object to be diagnosed, and the abnormality of the pair of FETs 25 and 26 can be diagnosed only by operating the electric motor 11 for diagnosis for a short time at the time of the initial diagnosis. The time for determining an abnormality can be reduced, and the generation of operation noise due to the operation of the electric motor 11 for detecting an abnormality can be suppressed in a very short time.
[0040]
Although the embodiments of the present invention have been described above, the present invention is not limited to the above embodiments, and various design changes can be made without departing from the present invention described in the claims. It is.
[0041]
For example, in the above embodiment, the case where the FET is used as the semiconductor switch has been described. However, the semiconductor switch is not limited to the FET as long as it is a semiconductor switch for turning on / off the power supply to the electric motor.
[0042]
【The invention's effect】
As described above, according to the present invention, it is possible to reduce the time for determining the abnormality of a pair of semiconductor switches, and to suppress the generation of operation noise due to the operation of the electric motor for abnormality detection in a very short time. Can be.
[Brief description of the drawings]
FIG. 1 is a hydraulic circuit diagram of a vehicle brake device.
FIG. 2 is a diagram showing a configuration of a driving device for an electric motor.
FIG. 3 is a flowchart illustrating an electric motor abnormality diagnosis processing procedure performed by a control unit;
FIG. 4 is a flowchart illustrating a procedure for determining an initial diagnosis target.
FIG. 5 is a flowchart illustrating an initial diagnosis processing procedure.
FIG. 6 is a timing chart for explaining a state in which an initial diagnosis target is switched every time an ignition is turned on.
FIG. 7 is a flowchart for illustrating a normal-time diagnosis processing procedure;
FIG. 8 is a diagram showing an example of a timing chart at the time of normal diagnosis after the completion of the initial diagnosis.
[Explanation of symbols]
11 ... Electric motor 25, 26 ... FET as semiconductor switch
27 ... Parallel circuit 28 ... Ignition switch 30 ... Control unit

Claims (1)

A pair of semiconductor switches (25, 26) connected in parallel to an electric motor (11) mounted on a vehicle, and both semiconductor switches (25, 26) are simultaneously turned on when the electric motor (11) is normally operated. A control unit (30) for outputting a drive signal for turning off the electric motor drive device, wherein the control unit (30) switches the ignition switch (28) each time the ignition switch (28) is turned on to switch the pair of semiconductor switches. An initial signal for outputting an ON signal for conducting one of (25, 26) for a predetermined time and diagnosing an abnormality of the semiconductor switch to which the ON signal is applied based on an actual power supply state to the electric motor (11). Diagnosing means and the two semiconductor switches (25, 2) during normal operation of the electric motor (11) after completion of the diagnosis by the initial diagnosing means. Electric motor drive device, characterized in that it comprises a normal diagnosis means for diagnosing abnormality of the parallel circuit (27) based on a potential difference occurring between both ends of) the parallel circuit consisting of (27).

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