JP2000184764A - Motor controller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a motor controller in which short circuit of a relay switch is detected and notified. SOLUTION: At first, an electronic control switch SW2 is turned off and then the switch SW1 of a motor drive circuit is turned on. Consequently, charges stored in the capacitors C1, C2 of a filter circuit 110 are discharged through the SW1 followed by a process of waiting a specified time required for discharging the capacitors C1, C2. Consequently, the capacitors C1, C2 are discharged sufficiently so long as a relay switch 180 is not short circuited. Subsequently, the SW1 is turned off and the potential difference ΔV(=VB-VC) between points C and B is inputted through an A/D converter 105. A short circuit alarm process is started if ΔV>ε is not satisfied.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motor drive circuit for controlling power supply by chopper control, a filter circuit for reducing propagation of noise generated by chopper control to a power supply, and a power supply and a filter circuit. The present invention relates to a motor control device having an electrically connected relay switch, and more particularly to a motor control device having a means for detecting a short-circuit state of the relay switch. The present invention can be applied to, for example, a motor control device of a DC motor that directly or indirectly drives (provides an assist torque) a power steering shaft or a power steering gear of an automobile.

[0002]

2. Description of the Related Art FIG. 7 shows a conventional electronic control unit (ECU).
FIG. 2 illustrates a hardware configuration diagram of a motor control device provided with a 900. This motor control device is mounted on a power steering system of an automobile. An electric pump P for supplying oil to a hydraulic gear of a power steering system is driven by a brushed DC motor M using a permanent magnet having a shunt characteristic. The DC motor M is driven by being supplied with power from a DC power supply 190. This DC supply power is MOS
The electronic control switches SW1 and MO constituted by FETs
Chopper control is performed by a motor drive circuit including the SFET drive circuit 102.

A filter circuit 110 including a coil L and capacitors C1 and C2 serves as a current smoothing circuit for a DC current flowing through a motor, and also prevents radio noise generated by chopper control from propagating to a power supply 190. The filter circuit 110 and the power supply 190 are connected by a relay switch 180. The relay switch 180 also functions as a safety device when the electronic control switch SW1 is not unduly turned off for some reason. In such an unexpected case, the relay switch 180 is turned off and the power supply 190 is unjustly turned off. Power consumption can be avoided. The opening and closing of the relay switch 180 is controlled by an electronic control switch SW2 constituted by a MOSFET. When the electronic control switch SW2 is ON, the relay switch 18 is turned on.
0 is also turned on. When the ignition switch IG is turned on, the CPU 101 turns the electronic control switch SW2 on. Thereby, the relay switch 180 is also turned on, so that the motor M can be driven by chopper control.

[0004]

SUMMARY OF THE INVENTION Relay switch 180
May cause a short circuit due to metal deposition or the like. In such a case, the relay switch 1
No. 80 may not function as the above-mentioned safety device. Therefore, a means for determining whether or not an electric contact of the relay switch 180 has short-circuited by measuring a potential difference between two points via the relay switch 180 can be considered. For example, the electronic control switch SW determines a potential difference ΔV (= V _B −V _C ) between the potential V _B at the point _B and the potential V _{C at the} point C in the conventional motor control device of FIG.
2 is a means for measuring when in the OFF state. According to this means, if the potential difference ΔV is larger than a certain reference value, it can be determined that the relay switch 180 is normal.

However, when the ignition switch IG is turned on and the relay switch 180 is turned on, the capacitors C1 and C
2, even if the relay switch 180 is in the OFF state, there is a possibility that V _C ≒ V _B.
When the short-circuit detecting means as described above is used in the conventional ECU 900, the short-circuit state of the relay switch 180 may be erroneously detected even though the electric contact of the relay switch 180 is not in contact. For this reason, detection of such a short circuit state has not been actually performed conventionally.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a motor control device capable of easily detecting the short circuit of the relay switch. An object of the present invention is to provide a motor control device having a relay switch short-circuit detecting means applicable to an automobile power steering system.

[0007]

In order to solve the above-mentioned problems, the following means are effective. That is, the first means includes a motor drive circuit that controls the amount of electric power supplied to the motor by chopper control, a filter circuit that reduces the propagation of noise generated due to the chopper control to the power supply, In a motor control device having a relay switch that electrically connects a power supply and a filter circuit that supplies the power and a electronic control switch that controls an open / close state of the relay switch, the relay switch is controlled to an open state by the electronic control switch. When the relay switch is controlled to be open by an electronic control switch after discharging by the discharging means for discharging the electric charge stored in the capacitor of the filter circuit.
Relay switch short-circuit detecting means for detecting a potential difference between two points via a relay switch or a potential difference between both terminals of a capacitor of a filter circuit, and a short-circuit for reporting a short-circuit state of the relay switch detected by the relay switch short-circuit detecting means Notification means. Note that the filter circuit may be a current smoothing circuit for a DC current flowing through the motor.

The second means is that, in the first means, the discharging means is operated after a main switch of a power supply is closed.

[0009] The third means may be the first or the second means.
In the means, the discharging means is operated after the main switch of the power supply is opened.

Further, the fourth means includes the first to third means.
In one of the above means, the motor is a DC motor that directly or indirectly drives a power steering shaft or a power steering gear of an automobile, and the main switch is an ignition switch of the automobile. That is. With the above means, the above-mentioned problem can be solved.

[0011]

According to the present invention, the electric charge stored in the capacitor of the filter circuit is discharged when the relay switch of the motor power supply is controlled to the open state by the electronic control switch in the motor control device. Therefore, if the relay switch is not short-circuited, after the discharge, no charge is accumulated in the capacitor of the filter circuit. Therefore, if the potential difference between two points via the relay switch or the potential difference between both terminals of the capacitor of the filter circuit is detected while the relay switch is controlled to be in the open state by the electronic control switch, the value is calculated as The short-circuit state of the relay switch can be determined,
Erroneous detection of a short circuit state is also eliminated. Further, the user can easily recognize the short-circuit of the relay switch by the short-circuit notifying unit that notifies the user of the detected short-circuit state of the relay switch. The short-circuit notification means includes, for example,
Any signaling device such as a pilot lamp, buzzer, or alarm can be used.

FIG. 2 is a general flowchart showing a general procedure of the relay switch short-circuit detecting process. The relay switch short-circuit detection processing is executed by the CPU of the motor control device when the electronic control switch that controls the open / close state of the relay switch is in the OFF state. In the relay switch short-circuit detection process, first, in step 220, a process of discharging the electric charge accumulated in the capacitor of the filter circuit is performed. The discharging process includes a process of opening and closing other electronic control switches required for discharging, a process of waiting for discharging time, and the like.
However, when the operation of opening and closing the electronic control switch is not required for discharging the electric charge accumulated in the capacitor of the filter circuit, this discharge processing may be only the processing for waiting for the discharge time.

Next, at step 240, a potential difference between two points via the relay switch or a potential difference between both terminals of the capacitor of the filter circuit is detected. Step 26
In the case of 0, the short circuit state of the relay switch is determined based on the detected potential difference.
The short circuit 80 is notified. If the above-described relay switch short-circuit detection processing is executed when the electronic control switch that controls the open / close state of the relay switch is in the OFF state, relay switch short-circuit detection and short-circuit notification can be performed.

If the relay switch short-circuit detection processing is executed in the sequence shown in FIG. 2 under the above-described execution conditions, the relay switch short-circuit detection and short-circuit notification can be performed at any timing. it can. That is, the above-described relay switch short-circuit detection processing may be performed at any of the following times. However, in order to perform the relay switch short-circuit detection processing at the following (time 2), the ECU needs a backup battery in addition to the power supply 190. (Timing 1) After the main switch (ignition switch) of the motor power supply is switched to the ON state. (Timing 2) After the main switch (ignition switch) of the motor power supply is switched to the OFF state. (Time 3) In the first half of the relay switch short-circuit detection processing, after the main switch of the motor power supply is switched to the OFF state, in the second half of the processing, the main switch of the motor power supply is turned on.
After switching to the state.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described based on specific embodiments. (First Embodiment) FIG. 2 shows an electronic control unit (E) according to the present invention.
1 shows a hardware configuration diagram of a motor control device including a CU) 100. FIG. This motor control device is
Equipped with the steering system, EC
U100 is similar to conventional ECU 900 (FIG. 7). That is, regarding the chopper control, the ECU 100
Performs exactly the same control as the conventional ECU 900 as follows.

An electric pump P for supplying oil to a hydraulic gear of a power steering system is a brushed DC motor M using a permanent magnet having a shunt characteristic.
Driven by The DC motor M is driven by being supplied with power from a DC power supply 190 such as a battery. This DC supply power is supplied to an electronic control switch SW1 composed of a MOSFET and a MOSFET drive circuit 1
The chopper control is performed by a motor drive circuit consisting of C.O. CPU101 is, RAM 103, ROM 104 is used as a storage device, performs an operation command voltage V _n to the motor in accordance with the vehicle speed u inputted from an unillustrated vehicle speed meter, the obtained command voltage V _n the MOSFET drive circuit 102
Output to

However, the present electronic control unit (ECU)
100 (FIG. 2) has the following points due to the hardware configuration.
It is different from CU900. That is, in the ECU 100, an A / D converter 105 and a voltage detector 106 composed of an analog amplifier having a feedback resistor are arranged as shown in the figure, and the voltage detector 106 has an ignition switch IG in an ON state and Electronic control switch SW2 is OFF
In the state, the potential difference ΔV between points C and B (= V _B −V _C )
To the A / D converter 105. The CPU 101 inputs the value of the potential difference ΔV via the A / D converter 105.

FIG. 3 shows an algorithm for more specifically executing the relay switch short-circuit detection processing (FIG. 1) in the present motor control device (FIG. 2). FIG. 3 is a flowchart of the short-circuit detection routine 1 in the present embodiment. This routine 1 is executed by the CPU 101 of the ECU 100 immediately after the ignition switch IG is switched to the ON state. That is, in this routine 1, the above (time 1) is adopted.

In this routine 1, first, at step 310, the electronic control switch SW2 is turned off (hereinafter simply referred to as turning off the switch SW2). In this step, the short-circuit detection processing of step 320 and subsequent steps is performed by SW2.
Is to be executed under the OFF state, and if this state is guaranteed immediately after the ignition switch IG is switched to the ON state,
It is not necessary.

Next, in steps 320 to 340, a discharging process corresponding to step 220 in FIG. 1 is performed. That is, in step 320, S of the motor drive circuit
Turn on W1. Thus, the charges stored in the capacitors C1 and C2 of the filter circuit 110 are discharged through the switch SW1. In step 330, a process for waiting for a predetermined time required for the discharge is performed. For example, the completion of the discharge can be waited for by using a timer to wait for a timer interrupt or performing a predetermined number of loop processes. By the above processing, the capacitors C1,
The charge stored in C2 is sufficiently discharged (grounded) as long as the relay switch 180 does not cause a short circuit. In step 340, SW1 is turned off.

Next, at step 350, FIG.
The potential difference corresponding to step 240 is detected. That is,
In step 350, the potential difference ΔV between point C and point B (= V_B
-V _C) Is input via the A / D converter 105. Stay
In step 360, a short circuit corresponding to step 260 in FIG.
Is determined. That is, in this step, the predetermined voltage ε
The magnitude relationship with the above potential difference ΔV is determined, and ΔV> ε
If not, go to step 380; otherwise, go to step 380.
The process moves to step 370. For example, the power supply voltage V_BIs 12
In the case of about [V], ε may be about 6 [V]. ε
Value V_BIf the discharge time is too close to the
And conversely make the value of ε too small
May not be able to detect the short circuit of the relay switch 180
Occurs.

In step 370, step 28 in FIG.
A short circuit corresponding to 0 is reported. That is, in this step, an abnormal process such as turning on the notification lamp on the front panel (not shown) of the driver's seat and stopping the motor is performed. On the other hand, in step 380 and below, the ignition
The conventional processing immediately after the switch IG is switched to the ON state is executed. That is, in step 380, SW2 is turned on.
I do. As a result, the relay switch 180 is turned on, and power can be supplied to the motor M. In step 390, the motor M is driven by chopper control.

As described above, by executing the relay switch short-circuit detection processing, the relay switch short-circuit detection and short-circuit notification can be performed.

(Second Embodiment) This embodiment is also implemented in the motor control device of FIG. 2 having the ECU 100 as in the first embodiment. In the above-described first embodiment, the relay switch short-circuit detection processing is executed by the short-circuit detection routine 1 at the (time 1). However, in the present embodiment, the relay switch short-circuit detection processing is performed at the (time 3). Short circuit detection routines 2 and 3 shown in 4 and 5
Execute by

FIG. 4 shows a flowchart of the short-circuit detection routine 2 of this embodiment. This routine 2 is executed by the ECU 100
Ignition switch IG by CPU 101
Is executed immediately after switching to the OFF state. In this routine, a series of processing from step 310 to step 340 is executed in exactly the same manner as the short-circuit detection routine 1 of the first embodiment.

FIG. 5 shows a flowchart of the short-circuit detection routine 3 of this embodiment. This routine 3 is executed by the ECU 100
Ignition switch IG by CPU 101
Is executed immediately after switching to the ON state. In this routine, a series of processes in steps 350 to 390 are executed in exactly the same manner as the short-circuit detection routine 1 of the first embodiment. As described above, if the relay switch short-circuit detection processing is executed, the relay switch short-circuit detection and the short-circuit notification can be performed as in the short-circuit detection routine 1 of the first embodiment.

In the motor control device shown in FIG. 2 having the ECU 100, the ignition switch IG is turned off.
When the FF state is not able to enter the potential V _B at the point B to the positive terminal of the voltage detector 106. Therefore, in the present motor control device, step 350 can be executed only when the ignition switch IG is in the ON state, so that the above (time 2) cannot be adopted. Hereinafter, a description will be given of a motor control device capable of executing the relay switch short-circuit detection processing at any of the timings (timing 1), (timing 2), and (timing 3). (However, as described above, in order to execute the relay switch short-circuit detection process at (time 2), a backup battery is required in the ECU.)

(Third Embodiment) FIG. 6 shows an ECU according to the third embodiment.
FIG. 2 shows a hardware configuration diagram of a motor control device provided with 200. This motor control device differs from the motor control devices of the first and second embodiments (FIG. 2) in the following points (1) to (3). (1) A discharging circuit 120 including a discharging transistor TR (hereinafter simply referred to as TR) and resistors R1 to R4 is connected to a point C. The resistance value of the resistor R2 is a sufficiently large value so that a large current does not flow even when TR is turned on. Further, since the resistance values of the resistors R1 and R4 are sufficiently large, TR is as follows.
5 can be controlled. (2) The discharge TR driving circuit 125 is connected to the CPU 101, and when the CPU 101 outputs a discharge suppression command to the circuit 125, the discharge of the discharge circuit 120 is suppressed. The discharge TR drive circuit 125 suppresses the above-described discharge by setting the output to the TR to a low potential state (turning off the TR) when a discharge suppression command is issued. (3) The voltage detector 106 detects a potential difference ΔV (= V _C −V _D ) between both terminals of the capacitor C2. Where V
_D is the potential on the negative terminal side of the capacitor C2.

In the ECU 200, when the ignition switch IG is turned off, the CPU 1
The power supply (not shown) is also turned off at the same time. Accordingly, the above-described discharge suppression command is not output from the CPU 101, and the discharge circuit 120 automatically discharges the capacitors C1 and C2. That is, in this case, the capacitors C1,
The electric charge from C2 generates a potential between the base and the emitter of TR, and TR becomes conductive (turns on). As a result, charges from the capacitors C1 and C2 are discharged through between the collector and the emitter of the TR.

Therefore, in the present motor control device, a desired relay switch short-circuit detection process can be realized only by executing the short-circuit detection routine 3 in FIG. However, in the third embodiment, the inequality sign (>) in step 360 must be replaced with the opposite direction (<). That is, in the present embodiment, in step 360 of the short-circuit detection routine 3, the magnitude relationship between the predetermined voltage ε and the above-described potential difference ΔV is determined, and if ΔV <ε, the process proceeds to step 380; The process moves to step 370. In addition, the CPU 1
When the power supply (not shown) is turned off, SW2 is also turned off at the same time.
F.

Also, by replacing "SW1" in steps 320 and 340 of FIG. 3 with "TR" and replacing the inequality sign ">" in step 360 with the inequality sign "<" in the short-circuit detection routine 1 of FIG. , A short-circuit detection routine 4), a desired relay switch short-circuit detection process can be realized in the motor control device (FIG. 6) including the ECU 200.

According to the short-circuit detection routine 4,
Since the potential difference ΔV (= V _C −V _D ) can be measured even when the IG is OFF, not only at (Timing 1) but also at (Timing 2), the motor control device including the ECU 200 (FIG. 6). As a result, a desired relay switch short-circuit detection process can be realized. However, as described above (time 2)
In order to implement the relay switch short circuit detection processing at
The ECU 200 requires a backup battery.

Further, in the motor control devices of the first and second embodiments (FIG. 2), the positive terminal of the voltage detector 106 is connected to the point B through the ignition switch IG. May be directly connected to the point B without passing through the ignition switch IG. If the positive terminal of the voltage detector 106 is connected in this manner, the relay switch short-circuit detection process can be performed at any of (timing 1), (timing 2), and (timing 3) by introducing a backup battery. It can be implemented.

The A / D converter 105 and the voltage detector 106 of the ECUs 100 and 200 are connected to the potential V _B ,
V _C, or it may be replaced with a comparator for inputting a potential V _C, V _D. Also in this case, a desired relay switch short-circuit detection process can be performed by using the voltage ε as a comparison reference value of the comparator and appropriately rewriting the short-circuit determination process of the step 360.

[Brief description of the drawings]

FIG. 1 is a general flowchart showing a general procedure of a relay switch short-circuit detection process.

FIG. 2 is a hardware configuration diagram of a motor control device including an ECU 100 according to the present invention.

FIG. 3 is a flowchart of a short-circuit detection routine 1 according to the present invention.

FIG. 4 is a flowchart of a short-circuit detection routine 2 according to the present invention.

FIG. 5 is a flowchart of a short-circuit detection routine 3 according to the present invention.

FIG. 6 is a hardware configuration diagram of a motor control device including an ECU 200 according to the present invention.

FIG. 7 is a hardware configuration diagram of a motor control device including a conventional ECU 900.

[Explanation of symbols]

106: Analog amplifier 110: Filter circuit (current smoothing circuit) 120: Discharge circuit 180: Relay switch 190: DC power supply IG: Ignition switch SW1, SW2: Electronic control switch (MOSFE)
T) C1, C2 ... capacitor L ... coil M ... DC motor P ... electric hydraulic pump Rj ... resistor (j is a natural number) TR ... discharge transistor V _B ... supply voltage

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H02P 7/00 H02P 7/00 P (72) Inventor Fukami Imai 1-1-1 Asahimachi, Kariya City, Aichi Prefecture Toyota Koki Co., Ltd. (72) Inventor Hirogo Nakagawa 1-1-1, Asahi-cho, Kariya-shi, Aichi Prefecture Toyota Koki Co., Ltd. F-term (reference) 3D033 CA33 EB06 5H550 AA16 BB08 CC04 DD01 DD06 FF03 GG03 HA01 HA04 HA08 HB12 JJ02 JJ03 JJ16 JJ26 KK06 LL01 LL52 MM01 MM09 5H570 AA21 BB09 CC04 DD01 DD06 FF03 HA01 HA04 HA08 HB12 JJ02 JJ03 JJ16 JJ17 JJ26 KK06 LL32 MM06 MM07 5H571 AA03 BB07 CC04 FF04 GG02 HA01 EJ04 GG02 HA01

Claims (4)

[Claims] A motor driving circuit for controlling the amount of electric power supplied to the motor by chopper control; a filter circuit for reducing propagation of noise generated by the chopper control to a power supply; A motor control device comprising: a relay switch that electrically connects the power supply and the filter circuit for supplying the power; and an electronic control switch that controls an open / close state of the relay switch. The electronic control switch causes the relay switch to open. A discharging means for discharging the electric charge stored in the capacitor of the filter circuit when being controlled to the state, and after the discharging by the discharging means, the relay switch is controlled to an open state by the electronic control switch. When there is a potential difference between two points via the relay switch,
A relay switch short-circuit detecting means for detecting a potential difference between both terminals of the capacitor; and a short-circuit notifying means for notifying a short-circuit state of the relay switch detected by the relay switch short-circuit detecting means. Motor control device. 2. The motor control device according to claim 1, wherein the discharging means operates after a main switch of the power supply is closed. 3. The motor control device according to claim 1, wherein the discharging unit operates after a main switch of the power supply is opened. 4. The motor is a DC motor that directly or indirectly drives a power steering shaft or a power steering gear of an automobile, and the main switch is an ignition motor of the automobile.
4. The switch according to claim 1, wherein the switch is a switch.
The motor control device according to any one of claims 1 to 4.