JP3819826B2 - Electric motor drive device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention includes 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 both the semiconductor switches during normal operation of the electric motor. In particular, 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 hydraulic pressure control device equipped with an electric motor, when the electric motor is driven by PMW, a semiconductor switch such as a field effect transistor connected to the electric motor generates heat, and further, performance degradation and failure occur. In order to suppress this, there is one in which a pair of the semiconductor switches are connected to an electric motor.
[0003]
[Problems to be solved by the invention]
Even when a pair of semiconductor switches are connected in parallel to the electric motor in this way, it is necessary to diagnose the abnormality of each semiconductor switch. At the time of failure diagnosis, each semiconductor switch is turned on for a predetermined time, and the electric motor is turned on. If the motor is operated, the time for abnormality diagnosis becomes uselessly long, and the operation sound of the electric motor becomes conspicuous.
[0004]
The present invention has been made in view of such circumstances, shortens the time for determining an abnormality of a pair of semiconductor switches, and generates an operation sound due to the operation of an electric motor for detecting an abnormality in a very short time. An object of the present invention is 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 simultaneously turning on and off both semiconductor switches during normal operation of the electric motor. In an electric motor drive device comprising a control unit for outputting a drive signal, the control unit outputs an ON signal for conducting one of the pair of semiconductor switches for a predetermined time by switching each time the ignition switch is conducted. And an initial diagnosis means for diagnosing an abnormality in the semiconductor switch on the side to which the ON signal is given based on a state of power supply to the actual electric motor, and both of the two during normal operation of the electric motor after the diagnosis by the initial diagnosis means is completed. An abnormality of the parallel circuit is diagnosed based on a potential difference generated between both ends of the parallel circuit composed of 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, so the on signal is The abnormality of the semiconductor switch on the assigned side can be diagnosed by the initial diagnosis means based on the power supply state to the actual electric motor. Also, during normal operation of the electric motor after completion of the diagnosis by the initial diagnosis means, if an abnormality occurs 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 that drives the motor flows, the amount of heat generated by the normal semiconductor switch increases, and when the amount of heat generated increases, the resistance value of the normal semiconductor switch increases. The potential difference between both ends increases. Therefore, an abnormality of the semiconductor switch different from the semiconductor switch diagnosed as normal in the initial diagnosis can be diagnosed by the normal time diagnostic means. Moreover, the semiconductor switch to be diagnosed by the initial diagnosis means is alternately switched every 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. Semiconductor switches are to be diagnosed, and it is possible to diagnose abnormalities in a pair of semiconductor switches by operating the electric motor for diagnosis for a short time at the time of initial diagnosis. It is possible to shorten the time for determining the occurrence of the operation, and it is possible to suppress the generation of the operation sound due to the operation of the electric motor for detecting the abnormality in a very short time.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below based on one embodiment of the present invention shown in the accompanying drawings.
[0008]
1 to 8 show an embodiment of the present invention, FIG. 1 is a hydraulic circuit diagram of a vehicle brake device, FIG. 2 is a diagram showing the configuration of an electric motor drive device, and FIG. 3 is a control unit. FIG. 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 an initial diagnosis target every time the ignition is turned on. FIG. 7 is a flowchart for illustrating a normal-time diagnosis processing procedure, and FIG. 8 is a diagram illustrating an example of a timing chart at the time of normal-time diagnosis after completion of the initial diagnosis.
[0009]
First, in FIG. 1, a tandem master cylinder M is provided with first and second output ports 1A and 1B for generating brake fluid pressure in accordance with a pedaling force applied to a brake pedal P by a vehicle driver. Wheel brake 2A, right rear wheel wheel brake 2B, right front wheel wheel brake 2C and left rear wheel wheel brake 2D, and first and second individually connected to the first and second output ports 1A and 1B, respectively. A brake fluid pressure control device 4 is provided between the output fluid pressure paths 3A and 3B.
[0010]
The brake hydraulic pressure control device 4 includes normally open solenoid valves 6A and 6B provided between the hydraulic pressure path 20A corresponding to the first output hydraulic pressure path 3A and the left front wheel brake 2A and the right rear wheel brake 2B. And the hydraulic pressure path 20B corresponding to the second output hydraulic pressure path 3B, the normally open electromagnetic valves 6C and 6D provided between the right front wheel brake 2C and the left rear wheel brake 2D, respectively, and the hydraulic pressure path 20A , 20B side check valves 7A, 7B, 7C, 7D connected in parallel to the normally open solenoid valves 6A-6D so as to allow the brake fluid to flow, and first and second output hydraulic pressure paths The first and second reservoirs 8A, 8B individually corresponding to 3A, 3B, and the normally closed provided between the first reservoir 8A and the left front wheel brake 2A and the right rear wheel brake 2B, respectively. The normally closed solenoid valves 9C and 9D, and the first and second reservoirs 8A and 8B provided between the solenoid valves 9A and 9B, the second reservoir 8B, the right front wheel brake 2C and the left rear wheel brake 2D, respectively. The first and second pumps 10A, 10B, the suction part of which is connected to the hydraulic pressure passages 20A, 20B, the common electric motor 11 for driving both pumps 10A, 10B, Normally closed solenoid valves 12A and 12B interposed between the suction portions of the first and second output hydraulic pressure paths 3A and 3B and the first and second pumps 10A and 10B, and the first and second pumps 10A and 10B, respectively. First and second dampers 13A and 13B, first and second pumps 10A and 10B, and first and second hydraulic pressure passages 20A and 20B, respectively. The first and second pumps 10A, 10B and the first and second orifices 14A, 14B provided between the two dampers 13A, 13B, and the first and second pumps 10A, 10B and the first pump 10A, 10B and the first pumps 10A, 10B, respectively. 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 path 3B, the first and second output hydraulic pressure paths 3A and 3B, and the liquid Regulators 21A and 21B 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 electromagnetic valves 5A and 5B, one-way valves 18A and 18B, and relief valves 19A, between the first and second output hydraulic pressure paths 3A and 3B and the hydraulic pressure paths 20A and 20B. 19B is connected in parallel.
[0013]
The one-way valves 18A, 18B are connected in parallel to the normally open solenoid valves 5A, 5B so as to allow the brake fluid to flow only from the first and second output hydraulic pressure paths 3A, 3B. The relief valves 19A and 19B are connected in parallel to the normally open solenoid valves 5A and 5B so as to open in response to the hydraulic pressure of the hydraulic pressure paths 20A and 20B becoming a predetermined value or higher.
[0014]
Such regulators 21A and 21B always communicate between the first and second output hydraulic pressure paths 3A and 3B and the hydraulic pressure paths 20A and 20B communicating with the master cylinder M, but the normally closed solenoid valves 12A and 12B. When the valve is opened, the output hydraulic pressure paths 3A, 3B and the hydraulic pressure paths 20A, 20B are shut off, and the hydraulic pressure paths 20A, 20B become higher than a set value in response to the hydraulic pressure of the hydraulic pressure paths 20A, 20B exceeding the set value. It operates so as to release the hydraulic pressure to the master cylinder M side, thereby adjusting the hydraulic pressure in 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 being output from the master cylinder M, that is, whether or not the brake pedal P is being depressed. This is used for controlling the rotational speed of the electric motor 11 according to the output hydraulic pressure of M.
[0016]
By the way, in the brake fluid pressure control device 4, during normal braking in which each wheel is not likely 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, the master 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 disconnected. Accordingly, the brake hydraulic pressure output from the first output port 1A of the master cylinder M acts on the left front wheel brakes and the right rear wheel brakes 2A and 2B via the normally open solenoid valve 5A and the normally open solenoid valves 6A and 6B. To do. The brake fluid pressure output from the second output port 1B of the master cylinder M is the right front wheel brakes 2C, 2D via the normally open solenoid valve 5B and the normally open solenoid valves 6C, 6D. Act on.
[0017]
When the wheel is about to enter the locked state during the brake, the normally open type electromagnetic valve corresponding to the wheel that is about to enter the locked state among the normally open type electromagnetic valves 6A to 6D is excited and closed. In addition, among the normally closed solenoid valves 9A to 9D, the normally closed solenoid valves corresponding to the wheels are excited and opened. As a result, the master cylinder M and the wheel brakes 2A to 2D are disconnected 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 that is 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 that is 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 excited and closed, and the normally closed solenoid valves 9A to 9D are demagnetized and closed, whereby the wheel brake 2A. ˜2D is disconnected from the master cylinder M and the reservoirs 8A and 8B.
[0019]
Further, when the brake fluid pressure is 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 disconnected.
[0020]
In this manner, the normally open solenoid valves 5A and 5B are demagnetized and opened, and the normally closed solenoid valves 12A and 12B are demagnetized and closed, and the normally open solenoid valves 6A to 6D and the normally closed solenoid valves are closed. By controlling the demagnetization / excitation of the valves 9A to 9D, braking can be performed efficiently without locking the wheels.
[0021]
By the way, during the antilock brake control as described above, the electric motor 11 is rotated, and the first and second pumps 10A and 10B are driven in accordance with the operation of the electric motor 11. Therefore, the first and second pumps are driven. The brake fluid absorbed in the reservoirs 8A and 8B is sucked into the first and second pumps 10A and 10B, and then passes through the first and second dampers 13A and 13B to the first and second output hydraulic pressure paths 3A and 3B. Refluxed. Such recirculation of the brake fluid can 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. In addition, the pulsation of the discharge pressures of the first and second pumps 10A and 10B is suppressed by the action of the first and second dampers 13A and 13B and the first and second orifices 14A and 14B. The ring is not disturbed.
[0022]
The brake fluid pressure control device 4 can perform side slip control and traction control of the vehicle in a non-brake 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, and the operation of the electric motor 11 is further performed. Thus, 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]
As a result, both pumps 10A, 10B allow the brake fluid of the master cylinder M to flow from the first and second output ports 1A, 1B to the first and second output hydraulic pressure paths 3A, 3B and the normally closed solenoid valves 12A, 12B. The brake fluid is supplied to the selected wheel brake 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]
When the hydraulic pressure in the hydraulic pressure passages 20A and 20B on which the discharge hydraulic pressure from the first and second pumps 10A and 10B acts during such side slip control and traction control becomes a set value or more, the relief valves of the regulators 21A and 21B 19A and 19B allow excess hydraulic pressure to escape to the master cylinder M side, so that excessive hydraulic pressure is prevented 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 pressure paths 20A and 20B and the orifices 14A and 14B, pulsations generated in the hydraulic pressure paths 20A and 20B due to 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 sound due to the pulsation caused by the operation of the regulators 21A and 21B.
[0027]
In FIG. 2, the electric motor 11 is connected with a parallel circuit 27 in which first and second field effect transistors (FET: hereinafter referred to as FET) 25 and 26 as a pair of semiconductor switches are connected in parallel. The parallel circuit 27 is connected to an in-vehicle battery 29 via an ignition switch 28.
[0028]
On / off of the first and second FETs 25 and 26 is controlled by the control unit 30, and during normal operation of the electric motor 11, the control unit 30 controls the first and second FETs 25, 25 to drive the electric motor 11 by PMW. A drive signal for simultaneously turning on and off 26 is output.
[0029]
In addition, the control unit 30 outputs an ON signal that makes one of the first and second FETs 25 and 26 conductive for a predetermined time so as to switch every time the ignition switch 28 is turned on, and an abnormality of the FET on the side to which the ON signal is given. On the basis of the actual power supply state to the electric motor 11 and 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 means. Normal time diagnosis means for diagnosing abnormality of the parallel circuit 27, and 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 the FETs 25 and 26 in accordance with the procedure shown in FIG. 3. In step S1, it is diagnosed whether or not the initial diagnosis has been completed. In step S3, an initial diagnosis is performed by the initial diagnosis means. If it is determined in step S1 that the initial diagnosis has been completed, a normal diagnosis is performed in step S3.
[0031]
By the way, which of the first and second FETs 25 and 26 is to be subjected to the initial diagnosis is determined by executing the processing 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 according to 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 odd, 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 odd and even, and when it is odd, the first FET 25 is driven for a predetermined time T (for example, 320 ms). A signal is output from the initial diagnosis means of the control unit 30, and when it is an even number, a signal for driving the second FET 26 for a predetermined time T is output from the initial diagnosis means of the control unit 30.
[0034]
After the process of step S12 or step S13 is completed, the process proceeds to step S14 to determine normality / abnormality of the FET to be diagnosed. Abnormality determination is performed based on the fact that normal power is not supplied to the motor 11.
[0035]
The normal diagnosis in step S3 is executed according to the subroutine shown in FIG. 7 by the normal diagnosis means. In step S21, it is determined whether or not the electric motor 11 is being driven. When the determination is made, 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 normal diagnosis is normal. If the potential difference is large, it is determined in step S24 that the FET that is the object of the normal diagnosis is abnormal.
[0036]
That is, as shown in FIG. 8, an ON signal for simultaneously conducting the first and second FETs 25 and 26 at the time of normal diagnosis after the first FET 25 is determined to be normal in the initial diagnosis with the first FET 25 as a diagnosis target. When the second FET 26 is abnormal at the time of output, only the normal first FET 25 is normal because the second FET 26, which is supposed to be conductive if normal, remains off as indicated by the solid line. A potential difference generated between both ends of the parallel circuit 27 composed of the first and second FETs 25 and 26 based on the fact that 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. Is increased, the potential difference is increased, and it is determined that the first FET 25 is 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. The control unit 30 that outputs a drive signal for simultaneously turning on and off the first and second FETs 25 and 26 during normal operation of the electric motor 11 is used every time the ignition switch 28 is turned on. Based on the actual power supply state to the electric motor 11, an ON signal is output that makes one of the first and second FETs 25, 26 conductive for a predetermined time. Of the parallel circuit 27 based on a potential difference generated between both ends of the parallel circuit 27 composed of the first and second FETs 25 and 26 during normal operation of the electric motor after completion of diagnosis by the initial diagnosis means. A normal time diagnosis means for diagnosing an abnormality.
[0038]
Therefore, when the ignition switch 28 is turned on to start the vehicle engine, an on signal is given to one of the first and second FETs 25 and 26 for a predetermined time, so 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. Further, during normal operation of the electric motor 11 after completion of the diagnosis by the initial diagnosis means, if an abnormality has occurred in the FET different from the FET diagnosed in the initial diagnosis, only the FET determined to be normal in the initial diagnosis has the electric motor 11. Since the current that drives the current flows, the amount of heat generated by the normal FET increases, and the resistance value of the normal FET increases by increasing the amount of heat generated. The potential difference between them increases. Therefore, the abnormality of the FET different from the FET diagnosed as normal in the initial diagnosis can be diagnosed by the normal diagnostic means.
[0039]
In addition, the FETs to be diagnosed by the initial diagnosis means are alternately switched every time the ignition switch 28 is turned on, and are different from the FETs to be diagnosed by the initial diagnosis means during normal operation of the electric motor 11. The FET is a diagnosis target, and it is possible to diagnose the abnormality of the pair of FETs 25 and 26 only by operating the electric motor 11 for diagnosis for a short time at the time of initial diagnosis. The time for determining the abnormality can be shortened, and the generation of the operation sound due to the operation of the electric motor 11 for detecting the 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-described 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-described 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 that turns 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 an abnormality of a pair of semiconductor switches, and to suppress the generation of operation noise due to the operation of the electric motor for detecting an abnormality in a very short time. Can do.
[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 an electric motor drive device.
FIG. 3 is a flowchart showing an abnormality diagnosis processing procedure of the electric motor by the control unit.
FIG. 4 is a flowchart showing a procedure for determining an initial diagnosis target;
FIG. 5 is a flowchart showing an initial diagnosis processing procedure;
FIG. 6 is a timing chart for explaining a state in which the initial diagnosis target is switched every time the ignition is turned on.
FIG. 7 is a flowchart for illustrating a normal-time diagnosis processing procedure;
FIG. 8 is a diagram illustrating an example of a timing chart during normal diagnosis after the initial diagnosis is completed.
[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 the electric motor (11) mounted on the vehicle and both the semiconductor switches (25, 26) are turned on simultaneously during normal operation of the electric motor (11). And a control unit (30) for outputting a drive signal for turning off the control unit (30), wherein the control unit (30) is switched every time the ignition switch (28) is turned on. An initial signal for outputting an ON signal for conducting one of (25, 26) for a predetermined time and diagnosing an abnormality in the semiconductor switch on the side to which the ON signal is applied based on the actual power supply state to the electric motor (11) During the normal operation of the diagnosis means and the electric motor (11) after completion of the diagnosis by the initial diagnosis means, the two semiconductor switches (25, 2 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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