JPH11108706A - Method and device for diagnosing failure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect a failure without applying a current whatever the failure may be and reduce weight and cost of a failure diagnosis device. SOLUTION: In a failure diagnosis device applied to a booster circuit 1 for generating power to drive switching elements Q1, Q3 on the higher side of a reversible-motor driving circuit 4 composed by connecting a DC motor M to a balancing point of a bridge circuit constituted of switching elements Q1 to Q4, the switching elements Q1 to Q4 constituting the bridge circuit and the booster circuit 1 are operated so as to provide a given measuring condition, terminal potential of the DC motor M is measured, and a failure of the booster circuit 1 is judged based on the measuring condition and the terminal potential measured correspondently thereto.

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. 5 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 switching elements Q1 and Q3 on the high side requires a voltage higher than the potential V _VB of the power supply terminal 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. in order to determine a failure of the booster circuit 100 is constituted by a boosted potential measuring means for measuring the boosted voltage V _VS terminal VS of the booster circuit 100, and determines the step-up circuit failure judging means for fault location of the booster circuit 100 ing.

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 V _VS 00, since it should be about twice the voltage of V _VB, can be determined abnormality of the booster circuit 100 is a monitor comparison between V _VB and V _VS.

That is, the monitor circuit 104 controls the booster circuit 10
Monitors the step-up voltage V _VS of 0, and supplies the V _VS to the CPU10 of the port P8. Similarly monitors V _VB in the monitor circuit 106, and supplies the V _VB to port P7 of CPU 101. The ports P7 and P8 have an A / D conversion function.

Then, the CPU 101 compares the supplied V _VB with V _VS and determines that the booster circuit 100 has failed if V _VS is not about twice the voltage of V _VB .

[0008] Incidentally, after the boosted voltage V _VS of the booster circuit 100 is confirmed to be normal, in order to actually 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.

[0009]

[SUMMARY OF THE INVENTION However, in the fault diagnosis method and device of such conventional booster circuit, requires a circuit for monitoring the boosted voltage V _VS, cost due to that much parts increases However, there is a problem that the ECU size and weight are increased, which is not preferable for mounting on a vehicle.

SUMMARY OF THE INVENTION 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.

[0011]

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 booster circuit operating means for operating a booster circuit for generating a drive power supply for the high-side switching element so as to satisfy a given measurement condition, and a terminal voltage measuring means for measuring a terminal potential of the motor to be driven And determining the failure of the booster circuit based on the measurement condition and the terminal potential measured correspondingly. In fault diagnosis apparatus characterized by comprising a judgment means.

[0012]

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 shown 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 resistor 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 of 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 arranged on the positive side (high potential side) power supply side from the motor terminal, and is a motor shown in FIG. 2 of the embodiment of the invention. Q1, Q3 in drive circuit 4
That is.

The "given measurement condition" defines the on / off state of the switching elements constituting the bridge circuit and the state of the booster circuit operating pulse. For example, all the switching elements are turned off. There will be multiple measurement conditions, such as turning on one particular switching element, stopping the boost pulse, and continuing to send the boost pulse.

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

The invention according to claim 2 of the present application 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 for generating drive power for an element based on a potential of a motor terminal, wherein all of the switching elements constituting the bridge circuit are performed in a state where the operation of the booster circuit is stopped. The motor terminal potential in the turned-off state is measured, and if the motor terminal potential is in the floating state, the process proceeds to the next step. On the other hand, if it is the positive power supply potential or the negative power supply potential, the switching corresponding to the potential is performed. A first step of diagnosing a short-circuit failure of the element or a power supply line short-circuit failure of the motor to be driven and ending the processing, From the state of one step, while turning on one of the switching elements on the high side of the bridge circuit, the motor terminal potential in that state is measured, and if it is in a floating state, the process proceeds to the next step. If the positive power supply potential is the second step of diagnosing the booster circuit as abnormal and ending the process, from the state of the second step, while operating the booster circuit, measure the motor terminal potential in that state, A third step of diagnosing that the booster circuit is normal and ending the process if it is the positive power supply potential, and diagnosing that the booster circuit is abnormal and ending the process if it is in a floating state; A failure diagnosis method characterized by the following.

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 that is in a floating state"
Usually, switching elements Q1 to Q
When all the terminals 4 are turned off, the potential of the motor terminal is indefinite. However, by connecting the power supply terminals VB and GND to the motor terminal M + or M- through a resistor as a monitor circuit, the potential of the resistance divided by the motor power supply is obtained. is determined by the V _R is measured.

Here, "while turning on one of the switching elements on the high side of the bridge circuit" in the second and subsequent steps means not only that any one of Q1 and Q3 is on, but also For example, turning on only Q1 to measure the terminal potential, then turning off Q1,
This includes a state in which an abnormality is determined by turning on Q3 and measuring the terminal potential.

According to the second aspect of the present invention, this type of boosting 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.

According to a third aspect of the present invention, in the third step of the failure diagnosis method according to the second aspect, the step-up circuit driving pulse is stopped in one of a high state and a low state after a normal operation and the motor terminal potential is stopped. And if it is the positive power supply potential, the booster circuit is diagnosed as normal and the process proceeds to the next step.If it is in the floating state, the booster circuit is diagnosed as abnormal and the process ends. After normal operation of the boost pulse, the other of the high and low stops and the motor terminal potential is measured. If it is the positive power supply potential, the boost circuit is diagnosed as normal and the process is terminated. And a step of ending the process after diagnosing a booster circuit abnormality, if any.

Here, "the boosting circuit drive pulse is stopped at one of the high and low levels after the normal operation" means that the boosting circuit is output by supplying a continuous high and low pulse train to the circuit. This means a type of circuit in which charge is sent to the output side and boosted by storing it on the output side.After sending this pulse train for a certain period of time to sufficiently boost the output side voltage, the drive pulse is set to high or low. This is a state in which it is stopped in one of the states.

According to the third aspect of the present invention, boosting such as an open failure of a capacitor for storing charge on the output side of a charge pump type boosting circuit, which cannot be found in the second aspect of the present invention. Depending on the state of the circuit drive pulse, it is possible to easily find a failure in a mode that is difficult to find.

[0027]

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. 5, 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-
Q4 driving power V _VS of the high-side switching element Q1, Q3 of the motor driving circuit 4 is configured to generate a.

The device for diagnosing the failure of the booster circuit 1 mainly includes switching element operating means for operating the switching elements Q1 to Q4 constituting the bridge circuit so as to satisfy given measurement conditions, A step-up pulse operating means for operating the step-up circuit 1 so as to satisfy a condition, a terminal potential measuring means for measuring a terminal potential of the DC motor M, and a measuring condition and a terminal potential measured corresponding thereto, based on: and determining failure location judgment means for failure position of the motor driving circuit 4, in order to determine a failure of the boosting circuit 1, and the boosted potential measuring means for measuring the boosted voltage V _VS of the booster circuit 1, the measurement conditions and correspondingly And a booster circuit failure determination means for determining a failure location of the booster circuit 1 based on the measured 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 (gate terminals of the power MOSFET in the figure) of the switching elements Q1, Q2, Q3, Q4 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 state of V _R shown in the following formula (hereinafter referred to as a floating state) becomes, the potential V _R is CP
Output to U2.

V _R = V _VB × ｛(R4 + R5) / (R3 +
R4 + R5)｝ Further, the monitor circuit 5 monitors the potential of the terminal M +, which is one terminal of the DC motor M,
Supply to port P6 having D conversion function. That is, the CPU 2 outputs a boost pulse operating signal from the output port P1 and outputs four systems of switching element operating signals from the output ports P2 to P5 in accordance with the given measurement conditions, thereby driving the motor. While the switching elements Q1 to Q4 constituting the circuit 4 are appropriately turned on and off, the monitoring circuit 5
, The potential of one terminal M + of the DC motor M is taken in from the port P6 of the CPU 2 having the A / D conversion function, and then the given measurement conditions and the potential of the one terminal of the motor measured corresponding to the given measurement conditions are By adapting to a predetermined algorithm, a failure location of the booster circuit 1 and the motor drive circuit 4 not described in detail here 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. , FIG. 4 shows the CPU 2
Is a flowchart showing another configuration of the failure diagnosis program executed in the first embodiment, and the details of a failure diagnosis apparatus and a failure diagnosis method according to the present invention will be systematically described with reference to these drawings.

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 this first step, first, “step-up pulse is stopped, Q1 to Q4 are all off” as initial conditions for measurement.
(Step 301), and the potential of the motor terminal M + measured in that state is referred to (Step 3).
02). Here, the terminal M + of the potential is determined V _R (floating state) other than (positive supply potential V _VB or negative power supply potential V _GND), the switching element Q1~Q4
Alternatively, it is determined that a short-circuit failure has occurred in any of the DC motors M, and the diagnosis processing is immediately terminated (step 30).
3). In contrast, when the terminal M + of the potential is determined V _R (floating state), diagnosis and shall not exist at least the above-mentioned short-circuit fault is made, followed by a second step is performed.

By performing the first step, a secondary failure that occurs when the switching element is turned on is prevented.

In the second step, first, "step-up pulse, ON only Q1" is given as a measurement condition (step 304), and in that state, the potential of the terminal M + is referred to (step 305). Here, the potential of the terminal M + is V _VB
If it is determined to be (positive power supply potential), it is diagnosed that a failure that cannot stop the operation of the booster circuit 1 has occurred, and the diagnostic processing is terminated (step 306). If the potential of the terminal M + is V _R (floating state), in addition to the normal stop of the booster circuit 1 and the possibility of an open failure of the switching element Q1, the measurement condition is changed to “turn off Q1, Q
3 is turned on ”(step 307), and the potential of the terminal M + is referred to (step 308). The potential of terminal M + is V _VB
Is measured, it is diagnosed that an open failure of the switching element Q1 and a failure that cannot stop the operation of the booster circuit 1 have occurred, and the diagnostic processing is terminated (step 30).
9). Still booster circuit 1 if the terminal M + of the potential V _R
Is diagnosed as having stopped normally, and the third step is executed.

In the third step, first, "start of boosting pulse, ON only Q1" is given as a measurement condition, and the boosting voltage _VVS is sufficiently increased by the boosting circuit 1 for a set time. After the elapse of the wax time (step 310), the potential of the terminal M + is referred to (step 311). If the potential is V _VB , it is diagnosed that the boosting is normal, and after the diagnosis end processing (step 313), the diagnosis processing is ended. If the potential of the terminal M + is V _R (floating state), it is diagnosed as a failure to stop the operation of the booster circuit 1 or an open failure of the switching element Q1, and the diagnostic processing ends (step 312).

In this way, the presence or absence of a failure of the booster circuit 1 is diagnosed.

However, for example, a charge-pump type booster circuit that sends a charge to the output side by supplying a high-low pulse train that is continuous with the circuit operation, and boosts the charge by storing it at the output side. In the case of confirmation, there is a failure mode that is difficult to find in the above method.
This is because when the output potential changes in synchronization with the booster circuit drive pulse, for example, when the drive pulse is high, the boosted potential is generated normally, but when the drive pulse is low, the boosted potential decreases. In the case of a failure (for example, the capacity of the accumulator C1 on the output side of the booster circuit 1 is missing), it is difficult to find out.

Therefore, the failure of the booster circuit 1 can be determined by executing a failure diagnosis program as shown in FIG. 4 instead of the third step described above. Note that the first step and the second step that constitute this program are the same processing as the first step and the second step described above, and a detailed description thereof will be omitted here.

In FIG. 4, after the processing of the first and second steps is completed, in the following fourth step, “start of boosting pulse, only Q1 is turned on” is given first, and the boosting pulse is set for a set time (by boosting circuit 1). After a lapse of time (the time when the voltage V _VS will rise sufficiently), the boost drive pulse is stopped once in a high state. After a lapse of a predetermined time (for example, a time during which an abnormality such as loss of capacity of the pressure accumulating capacitor C1 can be determined) after stopping in the high state (step 410), the potential of the terminal M + is referred to (step 411). Then, migrate the diagnostic potential thereof to a fifth step in the diagnosis of the booster normal if V _VB, if the terminal M + of the potential V _R (floating state), the operation stopping failure or switching of the step-up circuit 1 The diagnosis of the open failure of the element Q1 is made, and the diagnosis processing is terminated (step 412).

Next, in the fifth step, the measurement condition "restart of the boost pulse, ON only Q1" is given, and after the set time, the boost drive pulse is once stopped in a low state. After a lapse of a predetermined time (Step 413) after stopping in the low state, the potential of the terminal M + is referred to (Step 41).
4). If the potential is V _VB , it is diagnosed that the booster circuit is normal, and after the diagnosis end processing (step 416), the diagnosis processing is ended. Note terminal M + of the potential V _R If the (floating state), to diagnose the halt failure of the boosting circuit 1, and ends the diagnosis process (step 415).

By performing the failure diagnosis of the booster circuit 1 in such a manner, it is possible to surely find a failure in which the boosted output potential changes depending on the state of the boosting drive pulse.
The diagnosis at a set time and a predetermined time before the reference of the motor terminal potential is performed so that a change in the boosted output potential due to an abnormality of the booster circuit 1 appears remarkably and the failure determination is facilitated. Things.

Although a detailed description is omitted, as can be understood from the above description, the failure diagnosis of the booster circuit 1 of the present invention is performed so that the motor drive circuit 4, ie, the switching element Q1 constituting the motor drive circuit 4, The diagnosis of Q4 can be made to some extent. 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 mention 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 boosting drive pulse output from the port P1 of the CPU 2 in FIG. 1 is stopped, and the switching element drive signal output from the ports P2 to P5 is turned off. And the output to the DC motor M is prohibited, while the number of blinks of one warning light is
It is conceivable to make the difference depending on the failure of 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.

[0046]

As is apparent from the above description, according to the present invention, it is possible to diagnose a failure of a booster circuit portion without adding a monitor circuit of the booster circuit. In addition, the cost can be reduced.

[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 flowchart showing another configuration of the failure diagnosis program according to the present invention.

FIG. 5 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 Continuing on the front page (72) Inventor Hirotaka Kojima 1-4-4 Shiromi, Chuo-ku, Osaka-shi, Osaka NEC Home Electronics Co., Ltd.

Claims (3)

[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, wherein switching element operation means for operating a switching element constituting the motor drive circuit so as to satisfy a given measurement condition; and the high-side side so as to satisfy a given measurement condition. Step-up circuit operating means for operating a step-up circuit for generating a drive power supply for the switching element; terminal voltage measuring means for measuring a terminal potential of the motor to be driven; the measurement conditions and the terminal potential measured correspondingly And a booster circuit failure determination means for determining a failure of the booster circuit based on Failure diagnosis system. 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 operation of the booster circuit is stopped, and the motor terminal potential in a state in which all switching elements constituting the bridge circuit are turned off. Measure,
If it is in the floating state, the process proceeds to the next step. On the other hand, if it is the positive power supply potential or the negative power supply potential, the short-circuit failure of the switching element corresponding to that potential or the power supply line short-circuit failure of the driven motor. A first step of diagnosing the process and ending the process, from the state of the first step, while turning on any of the high-side switching elements of the bridge circuit, measuring the motor terminal potential in that state, If is floating, move to the next step,
If it is the positive power supply potential, a second step of diagnosing the booster circuit as abnormal and terminating the process, and measuring the motor terminal potential in that state while operating the booster circuit from the state of the second step A third step of diagnosing that the booster circuit is normal if the power supply potential is positive and ending the process while diagnosing that the booster circuit is abnormal if it is in a floating state and ending the process. A failure diagnosis method characterized by the above-mentioned. 3. The third step is to stop the booster circuit drive pulse in a high or low state after normal operation and measure the motor terminal potential. If the motor terminal potential is a positive power supply potential, the booster circuit is determined to be normal. While diagnosing and proceeding to the next step, if it is in a floating state, diagnosing a step-up circuit abnormality and ending the processing; Measuring the terminal potential, diagnosing that the booster circuit is normal if the power supply potential is the positive power supply potential and ending the process, and diagnosing the booster circuit as abnormal if it is in the floating state and ending the process; The failure diagnosis method according to claim 2, further comprising: