JP3483781B2 - Failure diagnosis method and device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a failure diagnosis method and apparatus, and more particularly to a failure diagnosis of a booster circuit for generating a drive power source for a switching element on the high side of an H-bridge type motor drive circuit using an N-channel switching element. A method and apparatus.

[0002]

2. Description of the Related Art A high-performance motor drive circuit using an N-channel switching element used in a conventional actuator operating motor of various vehicle systems (for example, vehicle control units such as antilock brake systems and transmission control systems). FIG. 4 shows an example of a failure diagnosing device for a booster circuit that generates drive power for a side-side switching element. In the motor drive circuit 103 shown in the figure, four switching elements (in the figure, constituted by power MOSFETs) Q1 to Q4 are connected in series and parallel between the power supply terminals VB and GND to form an H-type bridge circuit. In addition, the DC motor M to be driven is connected between the output terminals M + and M-, and the switching elements Q1 and Q4 or Q2 and Q3.
One element (Q2 or Q4) of the forward / reverse current path passing through
While the PWM pulse train is supplied to either of the above, the ON direction or the OFF signal is supplied to the other element (Q3 or Q1), thereby enabling the rotation direction control and the speed control.

Further, since the motor drive circuit 103 uses N-channel switching elements Q1 to Q4,
To operate the switching elements Q1 and Q3 on the high side, a voltage higher than the potential V _{VB of VB} is required. 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 equipped with a failure diagnosis device capable of self-diagnosing the failure location in order to speed up repair of the failure at a service station or the like. In short, switching element operating means for operating the switching elements Q1 to Q4 constituting the bridge circuit so as to obtain a given measurement condition, and boosting pulse operation for operating the booster circuit 100 so as to have a given measurement condition. Means, a terminal potential measuring means for measuring the terminal potential of the DC motor M, and a failure location determining means for determining the failure location of the motor drive circuit 103 based on the measurement conditions and the terminal potential measured corresponding thereto. In order to determine the failure of the booster circuit 100, the booster circuit 100 includes boosted potential measuring means for measuring the boosted voltage VS of the booster circuit 100 and booster circuit failure determination means for determining a failed portion of the booster circuit 100.

That is, the diagnosis of the booster circuit is, for example, a circuit in which the booster circuit can generate a voltage twice as high as D.
When the positive side (high potential side) power source potential V _VB of the C motor M is input, first, the booster circuit operating pulse is output to the booster circuit 100 from the port P1 of the CPU 101 configured by, for example, an 8-bit microcomputer. Next, 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.

In other words, the booster circuit 10 in the monitor circuit 104
The boosted voltage VS of 0 is monitored and this VS is supplied to the port P8 of the CPU 101. Similarly, in the monitor circuit 106, V _VB
Is monitored, and this V _VB is supplied to the port P7 of the CPU 101. The ports P7 and P8 have an A / D conversion function. Then, the CPU 101 compares the supplied V _VB and VS, and when VS is not substantially equal to 2V _VB , determines that the booster circuit 100 is out of order.

After confirming that the boosted voltage VS of the booster circuit 100 is normal, in order to perform actual control,
Since it is necessary to diagnose the main body of the motor drive circuit 103, the CPU 101 has a switching element operating means and a motor drive circuit abnormality determining means, and from any motor terminal (M + in this case) via the monitor circuit 105. Therefore, a circuit connected to the port P6 having an A / D conversion function is required.

[0008]

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

Therefore, the present invention has been made in order to solve the above-mentioned conventional problems, and an object thereof is to detect a failure without passing a current in any failure. Another object of the present invention is to provide a step-up circuit failure diagnosis method and apparatus that can reduce the weight and cost of the failure diagnosis apparatus of this type.

[0010]

The invention according to claim 1 of the present application is a reversible rotation type motor drive circuit in which a drive target motor is connected to the equilibrium point of a bridge circuit composed of N-channel switching elements. Is a fault diagnosis device applied to a booster circuit for generating a drive power source for a switching element on the high side of the switching element operation for operating the switching element constituting the motor drive circuit so as to meet 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 condition and the terminal potential measured corresponding thereto. Means, and a failure diagnosis device characterized by comprising.

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

The "bridge circuit" is not limited to the single-phase bridge circuit shown in the embodiment of the present invention, but widely includes multi-phase bridge circuits such as three-phase and six-phase.

Further, the term "balance point" is likened to the point where the potential is balanced in the case of a resistance bridge circuit, for the sake of easy understanding of the invention, and the point where the potential is actually balanced. Does not mean that. That is, this equilibrium point can be paraphrased as a connection point between the positive side switching element and the negative side switching element in the bridge circuit.

The "boost circuit" is a circuit for generating a higher potential power source from a power source of a certain potential.
For example, in the embodiments of the invention, the booster circuit is simply described, but the actual booster circuit refers to a circuit such as a charge pump type regulator or a boosting type switching regulator.

Further, the "high side switching element" is a switching element arranged on the positive side (high potential side) power source side from the motor terminal, and in the motor drive circuit 4 of the embodiment of the invention. This is Q1 and Q3.

Further, the "given measurement condition" defines the on / off state of the switching elements forming the bridge circuit. For example, one specific switching operation in which all the switching elements are in the off state. There may be multiple measurement conditions such as turning the device on.

Further, according to the invention described in claim 1, since the failure of the booster circuit is judged without directly reading the boosted voltage, the monitor circuit for measuring the boosted potential becomes unnecessary, and the device It is possible to reduce the size and weight and reduce the cost.

The invention according to claim 2 of this application is the switching on the high side of a reversible rotation type motor drive circuit in which a motor to be driven is connected to the equilibrium point of a bridge circuit composed of N-channel switching elements. A failure diagnosis method for diagnosing a failure of a booster circuit that generates driving power for an element based on a potential of a motor terminal, wherein the motor terminal potential is measured in a state in which all of the switching elements forming the bridge circuit are turned off. If it is in the floating state, the process moves to the next step.If it is the positive power supply potential or the negative power supply potential, the switching element on the side corresponding to that potential has a short circuit fault or the power supply line of the motor to be driven. The first step of diagnosing a short-circuit fault and ending the processing, and which of the high side of the bridge circuit The motor terminal voltage is measured in one state of being turned on only the switching element or,
If the difference between it and the terminal potential measured in the first step is greater than a predetermined first design value, the process proceeds to the next step, while if it is less than the first design value, a boost circuit abnormality or A second step of diagnosing the open failure of the switching element which is turned on and terminating the process, 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 If the difference between the motor terminal potential and the terminal potential measured in the first step is greater than or equal to the first design value, the process proceeds to the next step, while if it is less than the first design value, boosting is performed. Terminate the process by diagnosing a circuit abnormality or an open failure of the switching element that has been turned on.
And the second step or the third step in which the motor terminal potential is measured in the state where both the 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 predetermined second design value, the booster circuit is diagnosed as normal and the process ends, while if it exceeds the second design value, the booster circuit is determined. A fourth step of diagnosing an abnormality and terminating the process is provided.

Here, "the motor terminal potential is measured in a state where all the switching elements forming the bridge circuit are turned off, and it is in a floating state" means
Usually, switching elements Q1 to Q in the bridge circuit
When all 4 are turned off, the electric potential of the motor terminal is indefinite, but by connecting the power supply terminals VB and GND to the motor terminals M + and M- through a resistor as a monitor circuit, the electric potential of the resistance divided voltage of the motor power supply is obtained. It is determined by measuring VR.

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

According to the second aspect of the present invention, this type of boosting is 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. The failure diagnosis of the circuit can be appropriately performed.

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is a block diagram showing a schematic configuration of the failure diagnosis device according to the present invention. In the figure, the motor drive circuit 4 corresponds to a portion of the motor drive circuit 103 shown in FIG. 4 from which the DC motor M is removed.
Has a terminal VB that should be connected to the positive side (high potential side) power source.
And a terminal GND that should be connected to the negative side (low potential side) power supply
And a pair of terminals M to be connected to both sides of the DC motor M.
+ And 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.
Set to _GND .

The booster circuit 1 is the booster circuit 1 shown in FIG.
00 has the same configuration as that of the switching elements Q1 to Q1.
The drive power for the switching elements Q1 and Q3 on the high side of the motor drive circuit 4 constituted by Q4 is generated. The apparatus for diagnosing the failure of the booster circuit 1 mainly has switching element operating means for operating the switching elements Q1 to Q4 constituting the bridge circuit so that the given measurement condition is obtained, and the given measurement condition is provided. Based on the boosting pulse operating means for operating the boosting circuit 1, the terminal potential measuring means for measuring the terminal potential of the DC motor M, the measurement condition and the terminal potential measured corresponding thereto, the motor drive circuit No. 4 failure location determination means for determining the failure location, boosting potential measurement means for measuring the boosted voltage VS of the booster circuit 1 to determine the failure of the booster circuit 1, measurement conditions and corresponding measurement. The booster circuit failure determination means determines the failure location of the booster circuit 1 based on the terminal potential.

The CPU 2 is composed of a control 8-bit microcomputer in this example. A pulse train for driving the booster circuit is output from the output port P1 of the CPU2, and the switching elements Q1 to Q4 of the motor drive circuit 4 are output from the output ports P2 to P5 during the failure diagnosis process.
4 systems of signals for turning on and off are output, and these signals are supplied to the control input terminals (gate terminals of power MOSFETs in the figure) of the switching elements Q1, Q2, Q3, Q4 via the pre-driver 3. To be done. The pre-driver 3 is for converting the signal output from the CPU 2 into a signal that can drive the switching elements Q1 to Q4.

The monitor circuit 5 has the same structure as the monitor circuit 105 shown in FIG.
When all of 1 to Q4 are off, switching elements Q1 to Q4
If all DC motors M are normal, terminals M +, M
The potential of − becomes a state of VR shown by the following equation (hereinafter, this is called a floating state), and this potential VR becomes CP.
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, and C
It is supplied to the port P6 having the A / D conversion function of PU2. That is, the CPU 2 outputs the boosting operation signal from the output port P1 and outputs the switching element operation signals of the four systems from the output ports P2 to P5 in accordance with the given measurement conditions, whereby the motor drive circuit 4 On / off operations of the switching elements Q1 to Q4 that compose the above are appropriately performed, while the potential of one terminal M + of the DC motor M is set to A / via the monitor circuit 5 every time each measurement condition is given.
By taking in from the port P6 of the CPU 2 having the D conversion function, and then applying the given measurement condition and the one-sided terminal potential of the motor corresponding thereto to a predetermined algorithm, the booster circuit 1 and here A failure location of the motor drive circuit 4 not described in detail is determined.

Next, FIG. 2 is a circuit diagram showing the motor drive circuit 4, the monitor circuit 5 and the booster circuit 1 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. 2, the control input terminal Q of the switching element Q1 of the motor drive circuit 4
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 predriver 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 a V of the DC motor M is caused.
A B short circuit failure or a GND short circuit failure is determined. That is, in this first step, "all of Q1 to Q4 are turned off" is given as the initial measurement condition (step 301), and the potential V1 of the motor terminal M + is measured in that state (step 302). When this potential V1 is examined (step 303) and it is determined that V1 is other than VR (floating state) (V _VB or V _GND ), a short circuit failure occurs in any of the switching elements Q1 to Q4 or the DC motor M. It is determined that the error has occurred, and the diagnosis process 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 above-mentioned short-circuit fault does not exist, and then the second step is executed.

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

In the third step, similarly to the second step, "only Q3 is turned on" is given as a measurement condition (step 309), and the potential V3 of the motor terminal M + is measured in that state (step S309). 310). This potential V3 is compared with V1 measured in the first step (step 311), and if the difference between V3 and V1 is less than a predetermined value (design value 1), open failure of Q3 or boosting is performed. It is determined that Q3 cannot be turned on due to a circuit abnormality, and the diagnosis process is ended (step 312). On the other hand, V3 and V
If the difference from 1 is greater than or equal to the 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, "turn on Q1 and Q3" is given as the measurement condition (step 3
13) In that state, the electric potential V4 of the motor terminal M + is measured (step 314). This 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 set to a predetermined value. If it exceeds the value (design value 2), it is determined that the boosted voltage VS is insufficient and Q1 and Q3 cannot be turned on normally due to the abnormality of the booster circuit, and the diagnosis process is ended (step 316). On the other hand, if the difference between V4 and V2 (or V3) is less than or equal to the predetermined value (design value 2), it is diagnosed that the booster circuit is normal (step 317), and the diagnosis process ends.

Although detailed description is omitted, as can be understood from the above description, by performing the failure diagnosis of the booster circuit 1 of the present invention, the motor drive circuit 4, that is, the switching element Q1 constituting the motor drive circuit 4 is performed. -A part of the diagnosis of Q4 can be done. Therefore, if the diagnosis is performed in combination with the failure diagnosis of the motor drive circuit 4 which 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 an 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 mention a failure notification method for a failure of each part, various known notification means can be adopted for this. For example, when any failure is diagnosed, the switching element drive signal output from the ports P2 to P5 of the CPU 2 in FIG. 1 is fixed to the off side of the element, and the output to the DC motor M is prohibited. On the other hand, it is possible to make the number of blinks of one warning light different between the failure of the motor system and the failure of the booster circuit system or the switching element system. If such a notifying means is adopted, whether the repairer is on the side of the control unit having the motor drive circuit or on the side of the DC motor or the harness of the DC motor based on the number of times the warning light blinks. Can be easily discriminated and the time required for repairing a failure can be shortened.

[0034]

As is apparent from the above description, according to the present invention, it is possible to perform a failure diagnosis of the booster circuit portion without adding a monitor circuit. Therefore, a weight reduction and a cost reduction of this kind of failure diagnosis apparatus can be achieved. Is possible.

[Brief description of 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]

1 Booster circuit 2 CPU 3 pre-driver 4 Motor drive circuit 5 Monitor circuit Q1-Q4 switching elements

─────────────────────────────────────────────────── --- Continuation of the front page (56) Reference JP-A-8-332964 (JP, A) JP-A-8-207804 (JP, A) JP-A-8-84494 (JP, A) JP-A-7- 46885 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) H02P 5/00-5/26 H02P 7/00-7/34 B60T 8/88 H02H 7/20

Claims (2)

(57) [Claims] 1. A booster circuit for generating drive power for a switching element on the high side 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 composed of N-channel switching elements . late
A failure diagnosing device for diagnosing an obstacle based on a potential of a motor terminal, the switching element operating means for operating a switching element constituting the motor drive circuit so that a given measurement condition is satisfied, and A terminal voltage measuring means for measuring a terminal potential of the motor to be driven, and a booster circuit failure determining means for determining a failure of the booster circuit based on the measurement condition and the terminal potential measured corresponding thereto. and, all the switching elements constituting the bridge circuit
Measure the motor terminal potential in the off state,
If it is floating, move to the next step
On the other hand, if it is the positive power supply potential or the negative power supply potential,
If so, the side switching element corresponding to that potential is short-circuited
It is judged as a failure or a power supply line short circuit failure of the motor to be driven.
The first step of setting and terminating the processing, and one of the high side of the bridge circuit.
The motor with only the switching element turned on
The terminal potential is measured and it and the end measured in the first step
The difference from the child potential must be greater than or equal to the predetermined first design value.
If so, the process moves to the next step, while the first design value is not
If it is full, the booster circuit is abnormal or the switch turned on.
The second operation in which it is determined that the open failure of the switching element is completed and the processing ends.
And the side turned on in the second step of the bridge circuit is different.
Only the switching element on the high side is turned on.
The motor terminal potential in the state
The difference from the terminal potential measured in the step is less than the first design value.
If it is larger, move to the next step, while the first design
If it is less than the value, the booster circuit is abnormal or turned on.
It is judged as an open failure of the switching element and the processing is terminated.
Switching both the third step and the high side of the bridge circuit
Measure the motor terminal potential with the device turned on.
Constant and, at the same measured at the second step or third stearyl-up
The difference between the determined terminal potential and the predetermined second design value or more
If it is below, the booster circuit is diagnosed as normal and the process is terminated.
On the other hand, if it exceeds the second design value, it is judged that the booster circuit is abnormal.
Determine the step-up circuit by a fourth step of the process ends Te
A fault diagnosis device characterized by performing a determination . 2. A booster circuit for generating drive power for a switching element on the high side 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 composed of N-channel switching elements. A failure diagnosis method for diagnosing a failure based on the electric potential of a motor terminal, wherein the motor terminal electric potential is measured in a state in which all of the switching elements forming the bridge circuit are turned off,
If it is in the floating state, it moves to the next step, while if it is the positive power supply potential or the negative power supply potential, the switching element on the side corresponding to that potential has a short-circuit fault or the drive-target motor power line short-circuit fault. And the first step of terminating the processing and measuring the motor terminal potential in a state in which only one of the switching elements on the high side of the bridge circuit is turned on, and the measurement in the first step If the difference from the terminal potential is larger than a predetermined first design value, the process proceeds to the next step, while if it is less than the first design value, the booster circuit is abnormal or the switching element turned on is opened. Second, diagnosing failure and ending processing
And the first step of measuring the motor terminal potential in the 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 step 1 is larger than the first design value, the process proceeds to the next step, while if it is less than the first design value, the booster circuit is abnormal or the switching element that has been turned on has an open circuit failure. And a third step of terminating the processing by diagnosing the above, 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 less than or equal to the predetermined second design value, the booster circuit is diagnosed as normal and the process ends, while if it exceeds the second design value, the booster circuit is abnormal. A fourth step of diagnosing and ending the processing;