JPH1020001A - Failure diagnostic method for motor driving circuit and device therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a failure diagnostic device which can detect any failure without any supply of current and to accomplish reduction in weight and in a cost of this kind of device. SOLUTION: This failure diagnostic device is fitted in a reversibly rotatable motor driving circuit 1, in which a driving object motor M is connected to a valance position in a bridge circuit consisting of switching elements Q1-Q4. In this case, the switching elements Q1-Q4 constituting the bridge circuit are operated so that a given measurement condition is accomplished, and an electric potential of a predetermined one side terminal M+ of the driving object motor M is measured, and then, a failure position of the motor driving circuit 1 is determined on the basis of the measuring condition and the one side terminal electric potential measured in compliance with the measuring condition.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for diagnosing a failure of a motor drive circuit, and more particularly to a motor for operating an actuator of an antilock brake system (hereinafter referred to as ABS) for a vehicle. The present invention relates to a method and an apparatus for diagnosing a failure of a motor drive circuit which are suitable for the present invention.

[0002]

2. Description of the Related Art FIG. 4 shows an example of a motor drive circuit and a failure diagnostic device thereof conventionally used in an actuator operating motor of a vehicle ABS. The mode shown in FIG.
The data driver circuit 100 forms an H-type bridge circuit by connecting four switching elements (in the figure, constituted by power MOS-FETs) Q1 to Q4 in series and parallel between the power supply terminals VB and GND, Terminal M corresponding to the equilibrium point
A direct current motor M to be driven is connected between + and M-, and a forward / reverse current path via a pair of switching elements Q1 and Q4 or a pair of switching elements Q2 and Q3 which are located diagonally to each other. Supplies a PWM pulse train to one of the elements (Q2 or Q4), and the other element (Q
By supplying an ON signal or an OFF signal to 3 or Q1), rotation direction control and speed control can be performed.

On the other hand, this motor drive circuit is provided with a failure diagnosis device capable of self-diagnosis of a failure location in order to speed up the repair of a failure in a service station or the like. In short, this fault diagnosis apparatus measures switching element operating means for operating the switching elements Q1 to Q4 constituting the bridge circuit so as to satisfy a given measurement condition, and measures the terminal potentials on both sides of the motor M to be driven. It comprises a terminal potential measuring means and a fault location determining means for determining a fault location of the motor drive circuit 100 based on the measurement conditions and the two-sided terminal potential measured corresponding thereto.

That is, the terminal potentials of the terminals M + and M− located on both sides of the motor M are respectively set to the dedicated monitor circuit 10.
For example, an 8-bit micro computer
P (M +), P
(M-). These ports P (M
+) And P (M-) have an A / D conversion function.

The CPU 103 supplies a measurement on / off signal to each of the switching elements Q1 to Q4 from four dedicated output ports (not shown) in accordance with several measurement conditions prepared in advance, and measures each measurement. Motor M from port P (M +), P (M-) for each condition
Measure the terminal potentials on both sides of. Thereafter, by applying the given measurement conditions and the corresponding double-sided terminal potentials to a predetermined failure diagnosis algorithm,
The fault location and the fault content of the motor drive circuit 100 are determined.

Here, the failure location and the content of the failure in the motor drive circuit include (1) switching elements Q1 to Q4.
Is short-circuit failure (failure that cannot be turned off), (2) switching elements Q1 to Q
If any one of the motors 4 has an open fault (a fault that cannot be turned on), (3) if the motor M has a disconnection fault, (4) if the motor M has a VB short-circuit fault or GN
Four cases of D short-circuit failure are assumed.

[0007] In the failure diagnosis, several points must be noted. The first is that when performing a fault diagnosis,
The point is that a secondary failure due to a power supply short circuit must not occur. That is, in a state where one of the switching elements Q1 to Q4 has a short-circuit fault, if a switching element connected in series with the short-circuit fault is turned on by mistake, the power supply is short-circuited, a large current flows and a secondary fault occurs. Cause. Second, it must not have any effect on the load on the motor M. That is, in this example, since the output shaft of the motor M is connected to the brake actuator of the ABS, it is preferable that the motor M is not rotated during the failure diagnosis. Therefore, when diagnosing a failure, taking these points into account,
The measurement conditions are switched according to a certain procedure.
First, as a first step, "turn off all switching elements Q1 to Q4" is given as a measurement condition,
In that state, terminals M +,
The potential of M- is measured. In this case, when all of the switching elements Q1 to Q4 and the motor M are normal, the potentials of the terminals M + and M- are changed to the state of VR shown in the following equation (hereinafter referred to as the floating state). On the other hand, if a short-circuit fault has occurred in any one of the switching elements Q1 to Q4, or a VB short-circuit fault or a GND short-circuit fault has occurred in the winding or line of the motor M, the terminal The potential of M +, M- is VB or GND
Becomes

VR = VB × ｛(R2 + R3) / (R1 +
R2 + R3)｝ In this way, when a short-circuit failure of the switching elements Q1 to Q4 or a short-circuit failure of the power supply of the motor M is determined, the diagnosis is performed in order to avoid the occurrence of a secondary failure in the subsequent failure diagnosis. Stop processing immediately. On the contrary,
Only when it is determined that the above-mentioned short-circuit fault or power short-circuit fault does not exist, as a second step, the diagnosis of the open fault of the switching elements Q1 to Q4 and the disconnection fault of the motor M are performed. That is, the switching elements Q1 to Q4 are sequentially turned on one by one, and each time the potentials of the terminals M + and M− located on both sides of the motor M are measured. If you do this,
When all of the switching elements Q1 to Q4 are normal, the terminals M + or M
The-potential indicates VB or GND, whereas if any of the switching elements Q1 to Q4 has an open fault, the potential of the terminal M + or M- is set to the above-mentioned flow even if the switching element is turned on. In this case, the singing state is maintained. In addition, while the potential of one of the terminals M + and M- located on both sides of the motor M is VB or GND, the potential of the other terminal is floating.
If the motor M is in the running state, it can be determined that the motor M has a disconnection failure.

The monitor circuits 101 and 1 shown in FIG.
Numeral 02 has the same configuration, and includes potentiometers 101a and 102a comprising resistors R1 to R3, a capacitor C1 for removing a noise component contained in the output of the potentiometer, and a Zener diode. D1 and D2, the voltage level of which is not allowed due to noise or the like.
And clamp circuits 101b and 102b for avoiding input to the input ports P (+) and P (-).

[0010]

However, in such a conventional failure diagnosis apparatus for a motor drive circuit, the monitor circuit is required to measure the terminal potentials on both sides of the motor M. In addition to this, there is a problem that the cost is increased by that much, and that it is not preferable for mounting on a vehicle in terms of weight.

It is also conceivable to use one monitor circuit and switch it over with a switch to measure both terminal potentials. In this case, however, a new switch is required to achieve the purpose of cost reduction. Can not. Furthermore, if only one monitor circuit is used and only one terminal potential of the motor M is to be measured, it is not possible to diagnose a disconnection fault of the motor based on a difference between the potentials at both terminals of the conventional motor.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems, and an object of the present invention is to detect a failure without flowing a current in any failure. An object of the present invention is to provide a method and an apparatus for diagnosing a motor failure circuit which can reduce the weight and cost of this kind of failure diagnosis apparatus.

[0013]

The invention described in claim 1 of this application is applied to a motor drive circuit of a reversible rotation type in which a motor to be driven is connected to an equilibrium point of a bridge circuit constituted by switching elements. A switching element operating means for operating a switching element forming the bridge circuit so as to satisfy a given measurement condition, and a predetermined one-side terminal potential of the motor to be driven is measured. Terminal potential measuring means; and a fault location determining means for determining a fault location of the motor drive circuit based on the measurement conditions and the one-side terminal potential measured corresponding thereto. In the failure diagnosis device for the motor drive circuit.

Here, the term "switching element" is a general term for a power element having switching characteristics. In addition to the MOS-FET shown in the embodiment, a bipolar transistor, an electrostatic induction type Needless to say, transistors and the like are included.

The "bridge circuit" is not limited to the single-phase bridge circuit shown in the embodiment, but broadly includes a multi-phase bridge circuit such as three-phase or six-phase.

The term "equilibrium point" is likened to a point where the potential is balanced in the case of a resistive bridge circuit so that the invention can be easily understood. It does not mean that That is, this equilibrium point can be rephrased as a connection point between the positive switching element and the negative switching element in the bridge circuit.

The "given measurement condition" defines an ON / OFF state of a switching element constituting a bridge circuit. For example, a specific one switching element in which all switching elements are turned OFF. There may be multiple measurement conditions, such as turning on the power.

The "predetermined one-side terminal potential" means that only the potential of one of the two terminals located on both sides of the motor is measured. By switching the circuit with a switch,
This means eliminating the case where the potentials at both ends of the data are sequentially measured twice and measured one by one.

Further, "based on the measurement condition and the one-side terminal potential measured corresponding thereto" means "based on only one measurement condition and one single-side terminal potential measured correspondingly." The present invention is not limited to the case where the failure location is determined, and also includes the case where the failure location is determined based on two or more measurement conditions and two or more one-side terminal potentials measured corresponding thereto.

According to the first aspect of the present invention, since the failure point of the motor drive circuit is determined based on only one terminal potential, one monitor circuit for measuring the potential is provided. It is possible to reduce the weight and cost.

According to a second aspect of the present invention, the fault location determining means alternately switches a positive side switching element and a negative side switching element connected to the one terminal and the motor terminal opposite to each other, which are potential measurement points. 2. An open failure of the switching element and a disconnection failure of the motor are determined based on two measurement results obtained by turning on the motor.
4. A failure diagnosis device for a motor drive circuit according to (1).

Here, "positive and negative switching elements" means a high potential side and a low potential side, such as a VB potential side and a GND potential side.

According to the second aspect of the present invention, a disconnection fault of the motor can be determined without comparing the terminal potentials on both sides of the motor.

According to a third aspect of the present invention, a faulty portion of a reversible rotation type motor drive circuit in which a motor to be driven is connected to an equilibrium point of a bridge circuit constituted by switching elements is connected to one side of the motor. A failure diagnosis method for diagnosing based on a terminal potential, wherein one side terminal potential of the motor is measured in a state in which all of the switching elements constituting the bridge circuit are turned off. On the other hand, if it is a positive power supply potential or a negative power supply potential, a first step of diagnosing a short-circuit failure of the switching element corresponding to the potential or a short-circuit failure of the power supply line of the motor and terminating the process. And a positive side switch and a negative side switch connected to the potential measurement point side among the switching elements forming the bridge circuit. While the switching elements are turned on alternately, the one-side terminal potentials in the respective states are measured, and if they are the corresponding power supply potentials, the process proceeds to the next step, while if any of them is in the floating state, it is turned on at that time. A second step of diagnosing the open failure of the switching element to be performed and ending the processing, and a positive side and a negative side connected to the opposite side of the potential measurement point among the switching elements forming the bridge circuit. While the switching elements are turned on alternately, the one-side potential in each state is measured, and if any of them is the corresponding power supply potential, the circuit is diagnosed as normal and the processing is terminated. If the one-side terminal potential is in a floating state when the element is turned on, it is immediately diagnosed that the switching element has an open failure. Without referring to the one-side terminal potential when the other switching element is turned on, and diagnosing an open failure of the preceding switching element only when it is the corresponding power supply potential, while still in the floating state, A third step of diagnosing a disconnection failure of the motor and ending the processing, and diagnosing the motor drive circuit failure.

According to the third aspect of the present invention, the motor can be rotated without adversely affecting the load, or the power supply terminals can be short-circuited without causing a secondary failure. The failure diagnosis of the motor drive circuit can be appropriately performed.

[0026]

Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 is a block diagram showing a schematic configuration of a failure diagnosis device for a motor drive circuit according to the present invention. 4, a motor driving circuit 1 is a motor driving circuit 100 shown in FIG.
This corresponds to the part from which the data M has been removed.
The motor drive circuit 1 is connected to a terminal VB to be connected to a positive (high potential) power source, a terminal GND to be connected to a negative (low potential) power source, and to both sides of the motor M. A pair of power terminals M + and M- are derived.

In this example, the CPU 2 is constituted by an 8-bit control microcomputer. From the output ports P1 to P4 of the CPU 2, four signals for turning on and off the respective switching elements Q1 to Q4 of the motor drive circuit 1 are output during the failure diagnosis processing. Each of the switching elements Q1 to Q
4 is supplied to a control input terminal (gate terminal of a MOS-FET in the figure). From port P5 of CPU2,
A PWM pulse train for controlling the speed of the motor M is output,
This pulse train is supplied to one (Q4 or Q2) of a pair of output transistors (Q1 and Q4 or Q2 and Q3) on a diagonal line from each other via the pre-driver 3. Note that, at this time, the other transistor (Q1 or Q3) is kept on.

The monitor circuit 4 has the same configuration as the monitor circuit 101 or 102 shown in FIG. 4. The monitor circuit 4 monitors the potential of a terminal M + which is one terminal of the motor M, and monitors the potential of the terminal M +. It is supplied to the A / D conversion port P6 of the CPU 2. That is, the CPU 2 outputs four control signals from the output ports P1 to P4 in accordance with given measurement conditions, so that the switching elements Q1 to Q4 constituting the motor drive circuit 1 are appropriately controlled. On the other hand, each time the measurement conditions are given, the potential of one terminal M + of the motor M is taken in from the A / D port P6 via the monitor circuit 4 and then the given measurement conditions and the The fault location of the motor drive circuit 1 is determined by adapting the one-side terminal potential of the motor correspondingly measured to a predetermined fault diagnosis algorithm.

FIG. 2 is a circuit diagram showing the motor drive circuit 1 and the monitor circuit 4 in FIG. 1 in more detail, and FIG. 3 is a flow chart showing the configuration of a failure diagnosis program executed by the CPU 2. The details of the failure diagnosis device and the failure diagnosis method according to the present invention will be systematically described below with reference to these drawings.

In FIG. 3, when the failure diagnosis program is started, first, in a first step, a determination of a short-circuit failure of the switching elements Q1 to Q4, a VB short-circuit failure of the motor M, or a GND short-circuit failure. It is carried out.
That is, in the first step, "Q1 to Q4 all off" is given as the measurement condition (step 30).
1), one side terminal M + of the motor measured in that state
Is referred to (step 302). Here, when the potential of the terminal M + is determined to be the positive side (high potential side) potential VB, the two switching elements Q1, Q
No. 3 is diagnosed as having a short-circuit fault or the line of the motor M is causing a VB short-circuit fault, and the diagnosis process ends (step 303). When the potential of the terminal M + is determined to be the negative (low potential) power supply potential GND, it is determined whether one of the two switching elements Q2 and Q4 located on the GND side has a short-circuit failure, or A diagnosis is made that the line of the data M has a GND short-circuit failure, and the diagnosis process is immediately terminated (step 304). On the other hand, the potential of the terminal M + is VR
(Floating state), it is diagnosed that at least the short-circuit fault does not exist, and then the two switching elements Q located on the potential measurement point side
A second step is performed to diagnose an open fault in Q1, Q2.

In the second step, first, "only Q1 is turned on" is given as a measurement condition (step 30).
5) In this state, the potential of the terminal M + is referred to (step 306). Here, the potential of the terminal M + is VR
If it is determined that the switching element Q1 is in the floating state, the switching element Q1 is diagnosed as having an open failure (step 307), and the diagnosis processing ends. On the contrary,
If the potential of the terminal M + is VB, “ON only Q2” is further given as a measurement condition (step 30).
8) In this state, the potential of the terminal M + is referred to (step 309). Here, the potential of the terminal M + is VR
If it is determined that the switching element Q2 is in the floating state, the switching element Q2 is diagnosed as an open failure (step 310), and the failure diagnosis processing ends.

As described above, in the second step, it is determined on the basis of the potential of the terminal M + that the switching element that should have been turned on is not actually turned on. The device is diagnosed as having an open fault. On the contrary,
When the potential of the terminal M + is the measurement condition “only Q1 is ON”, V
GND when B and measurement condition "Only Q2 is ON"
In the case of (1), it is diagnosed that there is no open circuit fault in either of the switching elements Q1 and Q2, the second step is completed, and the terminal M- on the opposite side of the potential measurement point is continued.
A third step is executed for diagnosing an open failure of the two switching elements Q3 and Q4 connected to the motor M and a disconnection failure of the motor M.

In the third step, first, "ON only Q3 (switching element connected to VB side)" is given as a measurement condition (step 31).
1), the potential of the terminal M + in that state is referred to (step 312). Here, the potential of the terminal M + is VB
If it is determined that the switching element Q3 is open (floating state), "ON only the switching element Q4 (the switching element on the GND side)" is given as a measurement condition without immediately determining that the switching element Q3 has an open failure (step 31).
3), the potential of the terminal M + in that state is referred to (step 314). Here, the potential of the terminal M + is GND.
Is determined, the switching element Q3 is diagnosed as having an open failure (step 315), and the diagnosis processing ends. On the other hand, the potential of the terminal M + is VR
When it is determined that the motor M is in the floating state, the motor M is diagnosed as having a disconnection failure (step 316).
The diagnostic processing ends. On the other hand, in step 312,
When the potential of the terminal M + is determined to be VB, "ON only the switching element Q4 (GND-side switching element)" is continuously given as a measurement condition (step 317).
The potential of the terminal M + in that state is referred to (step 318). If the potential of the terminal M + is determined to be VR (floating state), it is diagnosed that the switching element Q4 has an open failure (step 31).
9), the diagnostic processing ends. On the other hand, when the potential of the terminal M + is determined to be GND, all the circuits are diagnosed as normal (step 320), and the diagnostic processing ends.

As described above, in the third step, when it is determined that the potential of the terminal M + in the state where either one of the switching elements Q3 or Q4 is turned on is in the floating state, the terminal is immediately turned on. Without determining the open failure of the switching element, which should have been performed, the potential of the terminal M + at the time of turning on the switching element on the opposite side should be referred to and turned on only when both potentials are different. While the switching element is determined to be an open fault, if both potentials are in the floating state, it is determined that the motor M is disconnected. As a result, unlike the conventional failure diagnosis device, the open-circuit failure of the motor M can be accurately diagnosed based on only the potential of one terminal M + without knowing the potentials of both terminals M + and M- of the motor M. It is possible to do.

As described above, according to the failure diagnosis program shown in FIG. 3, as a first step, it is confirmed that no short-circuit failure exists in any of the switching elements Q1 to Q4 and the motor M. Even if one of the switching elements is turned on for the subsequent diagnostic processing, there is no possibility that the power supply terminal VB-GND is short-circuited, thereby preventing the occurrence of a secondary failure.

In a second step following the first step, a pair of switching elements Q1,
Since the presence or absence of an open failure is diagnosed for Q2, the open failure of these switching elements can be immediately diagnosed.

In a third step following the second step, a terminal M + on the opposite side of the terminal M +, which is a potential measurement point, is used.
The open fault is determined for the two switching elements Q3 and Q4 connected to the negative terminal. At this time, the switching element Q3 and Q4 are alternately switched while referring to the potential of the terminal M + which is the potential measurement point. Therefore, the open fault of the motor M is not erroneously diagnosed as the open fault of the switching element Q3 or Q4, and the open fault and the open fault of the motor M can be accurately diagnosed. Becomes In addition, since only one terminal potential needs to be measured, only one monitor circuit is required as compared with a conventional failure diagnosis device, and the weight and cost of this type of diagnosis device can be reduced.

In the above-described fault diagnosis program, there is no mention of a fault notification method for a short-circuit fault, an open fault of the switching elements Q1 to Q4, and a disconnection fault of the motor. Notification means can be adopted. For example, if any failure is diagnosed, the port of CPU 2 in FIG.
While prohibiting the PWM pulse train output from the
It is conceivable that the number of blinks of one warning light is made different between a motor system failure and a switching element system failure. If such a notification means is employed, the repair worker can determine whether the faulty part is located on the control unit side where the motor drive circuit is mounted, based on the number of times the warning light blinks, or whether the motor or the motor Whether it is on the harness side can be easily determined, and the time required for repairing a failure can be reduced.

[0039]

As is apparent from the above description, according to the present invention, only one monitor circuit is required, so that the weight and cost of this type of fault diagnosis device can be reduced.

[Brief description of the drawings]

FIG. 1 is a block diagram schematically showing a failure diagnosis device for a motor drive circuit according to the present invention.

FIG. 2 is a circuit diagram showing in detail a motor drive circuit and a monitor circuit in the failure diagnosis device according to the present invention.

FIG. 3 is a flowchart showing the configuration of a failure diagnosis program according to the present invention.

FIG. 4 is a circuit diagram showing a conventional motor drive circuit failure diagnosis apparatus.

[Explanation of symbols]

 Reference Signs List 1 motor drive circuit 2 CPU 3 pre-driver 4 monitor circuit Q1 to Q4 switching element

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Kensuke Otake 1-4-24 Shiromi, Chuo-ku, Osaka City, Osaka Within NEC Home Electronics Co., Ltd. No. 1 Inside Honda R & D Co., Ltd.

Claims (3)

[Claims] 1. A failure diagnosis apparatus applied to a reversible rotation type motor drive circuit in which a motor to be driven is connected to an equilibrium point of a bridge circuit formed by switching elements, wherein a given measurement condition is satisfied. Switching element operation means for operating the switching elements constituting the bridge circuit, terminal potential measurement means for measuring a predetermined one-side terminal potential of the motor to be driven, and the measurement conditions and the measurement are performed in accordance with the measurement conditions. A failure location determination unit that determines a failure location of the motor drive circuit based on the one-side terminal potential. 2. The fault location determination means according to claim 1, wherein the two measurement points obtained by alternately turning on a positive side switching element and a negative side switching element connected to the one terminal and the motor terminal opposite to each other as a potential measurement point. 2. The failure diagnosis device for a motor drive circuit according to claim 1, wherein an open failure of the switching element and a disconnection failure of the motor are determined based on the result. 3. A failure diagnosis method for diagnosing a failed portion of a reversible rotation type motor drive circuit in which a drive target motor is connected to an equilibrium point of a bridge circuit constituted by switching elements based on one-side terminal potential of the motor. And measuring the one-side terminal potential of the motor in a state where all the switching elements constituting the bridge circuit are turned off, and if it is in a floating state, proceeds to the next step, while it is a positive side power supply. A first step of diagnosing a short-circuit failure of the switching element corresponding to the potential or a short-circuit failure of the power supply line of the motor if the potential or the negative power supply potential, and ending the processing; and a switching element forming the bridge circuit. Of the positive and negative switching elements connected to the potential measurement point side are alternately turned on. In this state, the one-side terminal potential is measured, and if they are the corresponding power supply potentials, the process proceeds to the next step, while if any of them is in the floating state, the open-circuit failure of the switching element that should be turned on at that time. A second step of diagnosing the process and terminating the process, and alternately turning on the positive and negative switching elements connected to the opposite side of the potential measurement point among the switching elements constituting the bridge circuit. The one-side potential in each state is measured, and if any of them is the corresponding power supply potential, the circuit is diagnosed as normal and the processing is terminated, whereas the one-side terminal when one of the switching elements is turned on. If the potential is in a floating state, the other switch is not immediately diagnosed as an open failure of the switching element. Refers to the one-side terminal potential when the switching element is turned on, and diagnoses the open failure of the preceding switching element only when the potential is the corresponding power supply potential. If the switching element is still in the floating state, the disconnection failure of the motor is performed. And a third step of ending the processing after diagnosing the failure.