JP2000125586A - Method and device for diagnosing failures - Google Patents

Abstract

PROBLEM TO BE SOLVED: To attain weight and cost reduction in a device for diagnosing failures by detecting failures, without passing current in any type of failure. SOLUTION: This device is provided for diagnosing failures and is applied to a boosting circuit 1 which generates the drive power supply of switching elements Q1, Q3 on the high side of a reversible motor drive circuit 4 formed by connecting a DC motor M to the equilibrium point of a bridge circuit, consisting of the switching elements Q1 to Q4. The switching elements Q1 to Q4 forming the bridge circuit are operated so as to obtain a given measuring condition, the terminal potential of the DC motor M is measured to determine the presence of a failure in the boosting circuit 1 in the measuring conditions, based on the terminal potential measured in the measuring conditions.

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, and more particularly to a failure diagnosis of a booster circuit for generating a drive power supply for a switching element on a high side of an H-bridge type motor driving circuit using an N-channel switching element. Method and apparatus.

[0002]

2. Description of the Related Art A conventional motor drive circuit using an N-channel switching element employed in an actuator operation motor of various vehicle systems (for example, a vehicle control unit such as an anti-lock brake system and a transmission control system). FIG. 4 shows an example of a failure diagnosis device for a booster circuit that generates a drive power supply for a switching element on the side. The motor drive circuit 103 shown in FIG. 1 forms an H-type bridge circuit by connecting four switching elements (formed of power MOSFETs in the figure) Q1 to Q4 in series and parallel between power supply terminals VB and GND. And a DC motor M to be driven is connected between its output terminals M + and M-, and the switching elements Q1 and Q4 or Q2 and Q3
One element (Q2 or Q4) in the forward / reverse current path passing through
While supplying a PWM pulse train to any one of the above, while supplying an ON signal or an OFF signal to the other element (Q3 or Q1), rotation direction control and speed control are enabled.

The motor drive circuit 103 uses N-channel switching elements Q1 to Q4.
The operation of the high-side switching elements Q1 and Q3 requires a voltage higher than the potential V _{VB of VB} . Therefore, the motor drive circuit 103 requires the booster circuit 100.

On the other hand, the booster circuit 100 and the motor drive circuit 103 are provided with a fault diagnosis device capable of self-diagnosis of a fault location in order to speed up fault repair at a service station or the like. In short, switching element operation means for operating the switching elements Q1 to Q4 constituting the bridge circuit so as to satisfy a given measurement condition, and boosting pulse operation for operating the booster circuit 100 so as to satisfy a given measurement condition Means, a terminal potential measuring means for measuring a terminal potential of the DC motor M, and a fault location determining means for determining a fault location of the motor drive circuit 103 based on the measurement conditions and the terminal potential measured corresponding thereto. The booster circuit 100 includes a boosted potential measuring unit that measures the boosted voltage VS of the booster circuit 100 to determine a failure of the booster circuit 100, and a booster circuit failure determination unit that determines a failure location of the booster circuit 100.

That is, the booster circuit is diagnosed by, for example, a circuit capable of generating a double voltage by the booster circuit.
When the positive (high potential) power supply potential V _VB of the C motor M is being input, first, a booster circuit operating pulse is output to the booster circuit 100 from the port P1 of the CPU 101 formed of, for example, an 8-bit microcomputer. Next, the booster circuit 1
00 boosts V _VB . Then, this booster circuit 1
Boosted voltage 00 VS, so should be approximately 2 times the voltage of V _VB, can be determined abnormality of the booster circuit 100 is in the comparison of the V _VB and VS.

That is, the monitor circuit 104 controls the booster circuit 10
The boosted voltage VS of 0 is monitored, and this VS is supplied to the port P8 of the CPU 101. Similarly, V _VB
Monitors, and supplies the V _VB to port P7 of CPU101. The ports P7 and P8 have an A / D conversion function. Then, the CPU 101 compares the supplied V _VB and VS, and determines that the booster circuit 100 has failed if VS is not substantially equal to 2V _VB .

After confirming that the boosted voltage VS of the booster circuit 100 is normal, in order to actually perform the control,
Since it is necessary to diagnose the main body of the motor drive circuit 103, the CPU 101 has a switching element operation unit and a motor drive circuit abnormality determination unit. Therefore, a circuit connected to the port P6 having the A / D conversion function is required.

[0008]

However, in such a conventional method and apparatus for diagnosing a failure of a booster circuit, a circuit for monitoring the boosted voltage VS is required, and the cost increases due to an increase in the number of parts. There is a problem that the ECU size and weight are increased, which is not preferable for mounting on a vehicle.

Therefore, 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. It is an object of the present invention to provide a failure diagnosis method and apparatus for a booster circuit that can reduce the weight and cost of this kind of failure diagnosis apparatus.

[0010]

According to a first aspect of the present invention, there is provided a motor drive circuit of a reversible rotation type wherein a motor to be driven is connected to an equilibrium point of a bridge circuit constituted by N-channel switching elements. A fault diagnosis device applied to a booster circuit for generating a drive power supply for a switching element on the high side of the switching device, wherein a switching element operating a switching element configuring the motor driving circuit so as to satisfy a given measurement condition. Means, a terminal voltage measuring means for measuring a terminal potential of the motor to be driven, and a booster circuit failure determination for determining a failure of the booster circuit based on the measurement conditions and the terminal potential measured corresponding thereto. Means for diagnosing a failure.

Here, the "N-channel switching element" is a general term for a power element having a switching characteristic, and is an N-channel switching element described in the embodiment of the present invention.
It goes without saying that an NPN bipolar transistor and the like are included in addition to the chMOSFET.

The "bridge circuit" is not limited to the single-phase bridge circuit described in the embodiment of the invention, 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 "boost circuit" is a circuit for generating a higher potential power supply from a power supply having a certain potential.
For example, in the embodiments of the present invention, it is simply expressed as a booster circuit, but an actual booster circuit refers to a circuit such as a charge pump regulator or a boost switching regulator.

The "high-side switching element" is a switching element disposed on the positive (high-potential side) power supply side from the motor terminal, and is used in the motor drive circuit 4 according to the embodiment of the present invention. Q1 and Q3.

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

According to the first aspect of the present invention, since the failure of the booster circuit is determined without directly reading the boosted voltage, the monitor circuit for measuring the boosted potential becomes unnecessary, and It is possible to reduce the size and weight and reduce the cost.

The second aspect of the present invention is directed to a high-side switching 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 N-channel switching elements. A failure diagnosis method for diagnosing a failure of a booster circuit that generates a drive power supply for an element based on a potential of a motor terminal, wherein the potential of the motor terminal is measured in a state where all switching elements constituting the bridge circuit are turned off. If it is in a floating state, the process proceeds to the next step. On the other hand, if it is a positive power supply potential or a negative power supply potential, a short-circuit failure of a switching element corresponding to the potential or a power supply line of a motor to be driven is performed. A first step of diagnosing a short-circuit fault and terminating the process, The motor terminal voltage is measured in one state of being turned on only the switching element or,
If the difference between the measured value and the terminal potential measured in the first step is larger than a predetermined first design value, the process proceeds to the next step. A second step of diagnosing the open failure of the turned on switching element and ending the processing, and a state in which only the switching element on the high side different from the side turned on in the second step of the bridge circuit is turned on. The motor terminal potential is measured. If the difference between the motor terminal potential and the terminal potential measured in the first step is larger than the first design value, the process proceeds to the next step. Diagnosing a circuit abnormality or an open failure of the switched-on switching element and terminating the processing.
And measuring the motor terminal potential in a state in which both switching elements on the high side of the bridge circuit are turned on.
If the difference from the terminal potential measured in the step is less than or equal to the second predetermined design value, it is diagnosed that the booster circuit is normal, and the processing is terminated. A fourth step of diagnosing the abnormality and ending the process.

Here, "measurement of the motor terminal potential in a state in which all of the switching elements constituting the bridge circuit are turned off, and the measurement is in a floating state"
Usually, switching elements Q1 to Q
4 are all turned off, the potential of the motor terminal is undefined. However, by connecting the power supply terminals VB and GND to the motor terminals M + and M- via a resistor as a monitor circuit, the potential of the motor power supply is divided by the resistance. It is determined by measuring VR.

The "first design value" and the "second design value" are the positive (high potential) power supply potential V _{VB of} the motor M to be driven, the characteristics of the switching element, and the resistance of the monitor circuit. It is a threshold for diagnosis that is determined in consideration of the pressure ratio and the like.

According to the second aspect of the present invention, this type of step-up can be performed without rotating the motor to be driven to adversely affect the load, or short-circuiting the power supply terminals to cause a secondary failure. Circuit failure diagnosis can be appropriately performed.

[0022]

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 according to the present invention. 4, the motor drive circuit 4 corresponds to a portion obtained by removing the DC motor M from the motor drive circuit 103 shown in FIG.
Terminal VB to be connected to the positive (high potential) power supply
And a terminal GND to be connected to a negative (low potential) power supply
And a pair of terminals M to be connected to both sides of the DC motor M
+, M- are derived. In this embodiment, the potential of the positive power supply is V _VB and the potential of the negative power supply is V _VB.
GND .

The booster circuit 1 includes a booster circuit 1 shown in FIG.
00 and the switching elements Q1-
A drive power supply for the switching elements Q1 and Q3 on the high side of the motor drive circuit 4 constituted by Q4 is generated. The device for performing the failure diagnosis of the booster circuit 1 mainly includes switching element operation means for operating the switching elements Q1 to Q4 constituting the bridge circuit so as to satisfy the given measurement condition, and the given measurement condition. Pulse operating means for operating the boosting circuit 1, terminal potential measuring means for measuring the terminal potential of the DC motor M, and a motor driving circuit based on the measuring conditions and the terminal potential measured corresponding thereto. 4, a failure location determination means for determining a failure location, a boosted potential measurement means for measuring a boosted voltage VS of the booster circuit 1 for determining a failure of the booster circuit 1, a measurement condition and measurement corresponding thereto. And booster circuit failure determination means for determining a failure location of the booster circuit 1 based on the terminal potential.

The CPU 2 is constituted by an 8-bit control microcomputer in this example. A pulse train for driving the boosting circuit is output from the output port P1 of the CPU 2, and the switching elements Q1 to Q4 of the motor drive circuit 4 are output from the output ports P2 to P5 at the time of failure diagnosis processing.
Are output to the control input terminals of the switching elements Q1, Q2, Q3, and Q4 (the gate terminals of the power MOSFETs in the figure) via the pre-driver 3. Is done. The pre-driver 3 converts a signal output from the CPU 2 into a signal that can be driven by the switching elements Q1 to Q4.

The monitor circuit 5 has the same configuration as the monitor circuit 105 shown in FIG.
When all of the switching elements Q1 to Q4 are off,
If all the DC motors M are normal, the terminals M +, M
The potential of-becomes the state of VR shown by the following equation (hereinafter referred to as a floating state).
Output to U2. VR = V _VB × ｛(R4 + R5) / (R3 + R4 + R
5)｝

Further, the monitor circuit 5 monitors the potential of the terminal M + which is one terminal of the DC motor M,
It is supplied to the port P6 of the PU2 having the A / D conversion function. That is, the CPU 2 outputs the boosting operation signal from the output port P1 and outputs four switching element operation signals from the output ports P2 to P5 in accordance with the given measurement conditions. The switching elements Q1 to Q4 are appropriately turned on and off, and the potential of one terminal M + of the DC motor M is changed to A /
The booster circuit 1 and the booster circuit 1 in this case are fetched from the port P6 of the CPU 2 having the D conversion function, and thereafter adapt the given measurement conditions and the one-side terminal potential of the motor measured corresponding thereto to a predetermined algorithm. A failure point of the motor drive circuit 4 (not described in detail) is determined.

FIG. 2 is a circuit diagram showing the motor drive circuit 4, monitor circuit 5 and booster circuit 1 in FIG. 1 in more detail, and FIG. 3 is a flowchart showing the configuration of a failure diagnosis program executed by the CPU 2. Hereinafter, the details of the failure diagnosis device and the failure diagnosis method according to the present invention will be systematically described with reference to these drawings. In FIG. 2, the control input terminal Q of the switching element Q1 of the motor drive circuit 4 is shown.
1a, the control input terminal Q2a of the switching element Q2, the control input terminal Q3a of the switching element Q3, and the control input terminal Q4a of the switching element Q4 are connected to the ports P2 to P5 of the CPU 2 via the pre-driver 3.

In FIG. 3, when the failure diagnosis program is started, first, in a first step, a short-circuit failure of the switching elements Q1 to Q4 or the V
The determination of the B short-circuit failure or the GND short-circuit failure is performed. That is, in the first step, "Q1 to Q4 are all turned off" is given as a measurement initial condition (step 301), and in that state, the potential V1 of the motor terminal M + is measured (step 302). After examining the potential V1 (step 303), if V1 is determined to be other than VR (floating state) (V _VB or V _GND ), a short-circuit fault occurs in either the switching elements Q1 to Q4 or the DC motor M. It is determined that an error has occurred, and the diagnostic processing is immediately terminated (step 304). On the contrary,
When the potential of the terminal M + is determined to be VR (floating state), it is diagnosed that at least the short-circuit fault does not exist, and then the second step is executed.

In the second step, "ON only Q1" is given as a measurement condition (step 305).
In this state, the potential V2 of the motor terminal M + is measured (Step 306). The potential V2 is compared with V1 measured in the first step (step 307), and V2
Is not greater than V1 by a predetermined value (design value 1) or more, that is, if the difference between V2 and V1 is less than design value 1, the open failure of Q1 or
It is determined that Q1 cannot be turned on due to the booster circuit abnormality, and the diagnosis process is terminated (step 308). On the other hand, if V2 is greater than V1 by a predetermined value (design value 1) or more, that is, if the difference between V2 and V1 is greater than or equal to a predetermined value (design value 1), at least the above-described failure does not exist. A diagnosis is made, followed by a third step.

In the third step, similarly to the second step, "ON only in Q3" is given as a measurement condition (step 309), and in that state, the potential V3 of the motor terminal M + is measured (step 309). 310). The potential V3 is compared with V1 measured in the first step (step 311). If the difference between V3 and V1 is less than a predetermined value (design value 1), the open failure of Q3 or the boost It is determined that Q3 cannot be turned on due to a circuit abnormality, and the diagnostic processing is terminated (step 312). On the other hand, V3 and V
If the difference from 1 is equal to or more than a predetermined value (design value 1), it is diagnosed that at least the above-mentioned failure does not exist, and then the fourth step is executed.

Next, in the fourth step, "Q1 and Q3 are turned on" is given as a measurement condition (step 3).
13) In this state, the potential V4 of the motor terminal M + is measured (Step 314). The potential V4 is compared with V2 measured in the second step (or V3 measured in the third step) (step 315), and the difference between V4 and V2 (or V3) is determined by a predetermined value. If the value exceeds the design value (design value 2), it is determined that the boosted voltage VS is insufficient due to the booster circuit abnormality and Q1 and Q3 cannot be normally turned on, and the diagnosis process is terminated (step 316). On the other hand, if the difference between V4 and V2 (or V3) is equal to or smaller than the predetermined value (design value 2), the booster circuit is diagnosed as normal (step 317), and the diagnostic processing ends.

Although the detailed description is omitted, as can be understood from the above description, the failure diagnosis of the booster circuit 1 according to the present invention is performed, so that the motor drive circuit 4, that is, the switching element Q1 constituting the motor drive circuit 4, is provided. Some diagnosis of Q4 can be made. Therefore, if the diagnosis is performed in combination with the failure diagnosis of the motor drive circuit 4 that can be safely performed with the same circuit configuration, the failure diagnosis of the booster circuit 1 and the motor drive circuit 4 is performed very efficiently and without any additional circuit. Therefore, it is possible to reduce the weight and cost of this type of failure diagnosis device.

Although the failure diagnosis program described above does not refer to a failure notification method for a failure of each part, various known notification means can be employed. For example, if any failure is diagnosed, the switching element drive signals output from the ports P2 to P5 of the CPU 2 in FIG. 1 are fixed to the off side of the element, and the output to the DC motor M is prohibited. On the other hand, it is conceivable that the number of blinks of one warning light is made different between a failure in the motor system and a failure in the booster circuit system or the switching element system. If such a notification means is employed, the repairer can determine whether the failure site is located on the control unit side where the motor drive circuit is mounted or on the DC motor or the harness side of the DC motor based on the number of times the warning light blinks. Can be easily determined, and the time required for repairing a failure can be reduced.

[0034]

As is apparent from the above description, according to the present invention, the failure diagnosis of the booster circuit can be performed without adding a monitor circuit. Becomes possible.

[Brief description of the drawings]

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

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

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

FIG. 4 is a circuit diagram showing a conventional failure diagnosis device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Step-up circuit 2 CPU 3 Pre-driver 4 Motor drive circuit 5 Monitor circuit Q1-Q4 Switching element

 ──────────────────────────────────────────────────続 き Continued on the front page F-term (reference)

Claims (2)

[Claims] 1. A step-up circuit for generating a drive power supply for a switching element on a high side of a reversible rotation type motor driving circuit in which a motor to be driven is connected to an equilibrium point of a bridge circuit constituted by N-channel switching elements. A failure diagnosis device to be applied, comprising: switching element operation means for operating a switching element constituting the motor drive circuit so as to satisfy a given measurement condition; and terminal voltage measurement for measuring a terminal potential of the motor to be driven. A failure diagnosis device comprising: means; and a booster circuit failure determination means for determining a failure of the booster circuit based on the measurement condition and the terminal potential measured corresponding thereto. 2. A step-up circuit for generating a drive power supply for a switching element on a high side of a reversible rotation type motor driving circuit in which a motor to be driven is connected to an equilibrium point of a bridge circuit composed of N-channel switching elements. A failure diagnosis method for diagnosing a failure based on a potential of a motor terminal, wherein the motor terminal potential is measured in a state in which all switching elements constituting the bridge circuit are turned off,
If it is in a floating state, the process proceeds to the next step. If it is a positive power supply potential or a negative power supply potential, a short-circuit failure of the switching element corresponding to the potential or a power supply line short-circuit failure of the driven motor. A first step of diagnosing and terminating the process; and measuring the motor terminal potential in a state where only one of the high-side switching elements of the bridge circuit is turned on, and measuring the potential in the first step. If the difference from the set terminal potential is greater than or equal to a predetermined first design value, the process proceeds to the next step. If the difference is less than the first design value, the booster circuit is abnormal or the opened switching element is opened. Diagnosis of failure and end of process 2
And measuring the motor terminal potential in a state where only the switching element on the high side different from the side turned on in the second step of the bridge circuit is turned on.
If the difference from the terminal potential measured in the step is larger than the first design value, the process proceeds to the next step. If the difference is smaller than the first design value, the booster circuit is abnormal or the switching element that has been turned on has an open fault. A third step of diagnosing the process and terminating the process; and measuring the motor terminal potential in a state where both switching elements on the high side of the bridge circuit are turned on, and the second step or the third step If the difference from the terminal potential measured in step 2 is equal to or less than a predetermined second design value, the booster circuit is diagnosed as normal, and the process is terminated. A fourth step of diagnosing and terminating the process, comprising: