JP2005102358A - Motor drive circuit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To judge the abnormality of a drive circuit when a motor is not driven, in a motor drive circuit for forward driving/backward driving of the motor. <P>SOLUTION: The motor drive circuit (1) comprises two relays (31, 32) and relay driving means (7, 33, 35) for on/off driving the two relays. A motor M is driven forward or backward by turning one relay on while the other relay off. The motor drive circuit further comprises a current supply means (2) which supplies a drive current to the motor based on a drive signal, a relay state detecting means (4) which detects the state of the two relays while supplying of the drive current to the motor M is stopped, and an abnormality judging means (7) which judges presence of abnormality in the motor drive circuit by comparing the state of the relay which is set by the relay driving means to the state of the relay which is detected by the relay state detecting means. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a motor drive circuit.

  2. Description of the Related Art Conventionally, a transfer device provided in a so-called part-time four-wheel drive vehicle has a gear set in a high speed (high (H) mode) and a low speed (low (L) mode) by driving a motor in a normal rotation / reverse rotation. ), And the wheel drive state is switched between two-wheel drive (2WD mode) and four-wheel drive (4WD mode). This type of transfer device is shown in FIG. As described above, a motor drive circuit including two relays and a motor forward / reverse drive check circuit has been provided.

Then, each of the relays is driven on / off to drive the motor in the normal rotation direction or the reverse rotation direction, while the motor forward / reverse rotation drive check circuit detects the direction in which the motor is actually driven to detect a circuit abnormality. The motor is prevented from being driven in an unexpected direction due to (relay abnormality) or the like.
On the other hand, in recent years, a transfer device has been proposed in which a switching operation between the H mode and the L mode and a switching operation between the 2WD mode and the 4WD mode are performed by one motor. Some transfer devices have been developed that control the motor to switch between (high speed) two-wheel drive mode (2WD mode), high-speed four-wheel drive mode (4H mode) or low-speed four-wheel drive mode (4L mode). (See Patent Document 1).
JP-A-10-109563

By the way, in the motor drive circuit (FIG. 3) described above, the motor is driven when one of the relays is turned on, and the circuit (relay) is determined to be abnormal in the motor drive state. ing.
However, such abnormality determination is performed by driving the motor to one side (forward rotation side) or the other side (reverse rotation side) to drive the switching mechanism to a position corresponding to the H mode or L mode, respectively. When switching modes, that is, when switching the drive mode at 2 points, no problem occurs, but when switching the drive mode at 3 points as in the transfer device described in the above publication, apply as it is. I can't.

  That is, when switching at 3 points, the drive mode is switched at an intermediate position as compared with switching at 2 points. However, if a circuit abnormality has occurred at this intermediate position, In such an abnormality determination, the motor operates during the abnormality determination, and even if it is determined as abnormal (detection of abnormality) and the motor is stopped, it cannot be stopped at the intermediate position and is not intended. This is because there is a possibility that the vehicle may stop, and as a result, the vehicle may not be able to start or may move freely.

Therefore, it is desirable that the abnormality determination of the motor drive circuit that switches the drive mode at three points as in the transfer device described in the above publication is performed in the motor non-drive state.
The present invention has been made paying attention to such a situation, and an object of the present invention is to provide a motor drive circuit capable of performing an abnormality determination in a motor non-drive state.

  For this reason, the invention described in claim 1 has two relays and relay driving means for driving the two relays on and off, respectively, and one of the relays is turned on and the other relay is turned on. A motor drive circuit for driving the motor in a normal rotation direction or a reverse rotation by turning it off, current supply means for supplying a drive current to the motor based on a drive signal, and supply of the drive current to the motor stopped A relay state detecting means for detecting the state of the two relays in a state where the relay is operated, a relay state set by the relay driving means, and a relay state detected by the relay state detecting means And an abnormality determining means for determining whether there is an abnormality in the motor drive circuit.

  In this case, the relay state detection means detects the actual relay operation state (ON / OFF) in the motor non-driving state, and the abnormality determination means detects the actual relay operation state detected by the relay state detection means. The operation state of the relay set by the relay drive means is compared, and it is determined that there is an abnormality in the motor drive circuit (relay) when the two operation states are different. Thereby, abnormality of a motor drive circuit can be determined beforehand before motor drive.

According to a second aspect of the present invention, the relay drive means turns off the two relays when supply of drive current to the motor is stopped, and the abnormality determination means is the relay state detection means. Thus, when it is detected that either one of the relays is in the ON state, it is determined that there is an abnormality.
In this way, the relay state detection means only needs to be able to detect that either one of the two relays is in the on state, so that the relay state detection means can have a relatively simple configuration (a circuit thereof).

According to a third aspect of the present invention, when the abnormality determination means determines that there is an abnormality, the supply of drive current to the motor is prohibited.
As a result, it is possible to reliably prevent a situation in which the motor operates arbitrarily and rotates to an unexpected position.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a block diagram showing the overall configuration of a motor drive circuit according to an embodiment of the present invention. For example, in a part-time four-wheel drive vehicle, the transfer device 2 is controlled by controlling the rotation direction and rotation angle. The present invention can be applied to a drive mode switching motor that switches between a wheel drive mode (2WD mode), a high-speed four-wheel drive mode (4H mode), and a low-speed four-wheel drive (4L mode). An example of such a transfer device is disclosed in Japanese Patent Application Laid-Open No. 10-109563, and a description thereof is omitted here.

As shown in FIG. 1, a motor drive circuit 1 according to the present embodiment includes a current control circuit 2, a motor forward / reverse circuit 3, a motor forward / reverse check circuit 4, a motor forward / reverse drive check circuit 5, and a current detection. The circuit 6 includes a controller 7 that controls these circuits in an integrated manner.
The motor M is a so-called torque variable motor, and generates an output torque corresponding to a drive current (load current) when energized.

  The current control circuit 2 is provided on the upstream side of the motor M, and is connected to the drive power source BAT when the ignition switch 8 is turned on. Then, a drive current is supplied to the motor M based on a drive signal from the controller 7, and its output torque is controlled. The switching mechanism in the transfer device (not shown) is driven to a position corresponding to the 2WD mode, 4H mode, or 4L mode according to the output torque of the motor M.

The motor forward / reverse circuit 3 is provided on the downstream side of the current control circuit 2 and includes a first relay 31 and a second relay 32. Then, when one of the first relay 31 and the second relay 32 in the off state is turned on (the other is in the off state) according to the drive signal from the controller 7, the motor M is driven forward or reverse. A circuit to be driven is formed.
For example, when the first output processing circuit 33 energizes the first relay coil 34 by the drive signal from the controller 7, the first relay 31 is turned on (the second relay 32 remains off), and the motor M Is supplied with a drive current from the first relay 31 side to the second relay 32 side, and the motor M is driven forward. On the other hand, when the second output processing circuit 35 energizes the second relay coil 36, the second relay 32 is turned on (the first relay 31 remains off), and the motor M is connected to the second relay 32 side. A drive current directed toward the first relay 31 is supplied, and the motor M is driven in reverse.

  The motor forward / reverse check circuit 4 is connected between the current control circuit 2 and the motor forward / reverse circuit 3, and when the drive current is not supplied from the current control means 2 (that is, the motor M is in the non-drive state). Sometimes, the on / off state of the first relay 31 and the second relay 32 is detected, and the detection result is output to the controller 7. For this detection, a part of the motor forward / reverse check circuit 4 is configured as shown in FIG. 2 using, for example, a check voltage Vc and resistors R1 and R2, and the voltage Vx at the connection point X is monitored. And at least detecting that the first relay 31 and the second relay 32 are in the off state or that any one of the relays is in the on state.

  The motor forward / reverse drive check circuit 5 is provided to be connected between the first relay 31 and the motor M and between the second relay 32 and the motor M, and is driven from the current control circuit 2 to the motor M. When a current is supplied (that is, when the motor M is in a driving state), it is determined whether the motor M is actually driven in the forward direction or the reverse direction (whether it is driven), and the determination result Is output to the controller 7. Such a determination is made, for example, by detecting the voltage on the first relay 31 side and the voltage on the second relay 32 side of the motor M and comparing the detected voltages.

The current detection circuit 6 detects the current flowing through the motor M and outputs the detection result to the controller 7.
Then, the controller 7 switches the transfer device from the current drive mode to the selected drive mode based on an operation signal (2WD, 4H, 4L) of a drive mode switch (not shown) operated by the driver. The current control circuit 2 is feedback-controlled, and the relays 31 and 32 of the motor forward / reverse circuit 3 are turned on / off. Further, based on the determination results of the motor forward / reverse rotation check circuit 4 and the motor forward / reverse rotation drive check circuit 5, the abnormality determination of the motor drive circuit is performed before the motor M is driven and during the drive of the motor M.

Next, the operation of the motor drive circuit configured as described above will be described.
When the ignition switch 8 is turned on, first, the state of the first relay 31 and the second relay 32 is detected by the motor forward / reverse rotation check circuit 4, and the detection result is output to the controller 7. Specifically, when the voltage (monitoring voltage) Vx is a value within a predetermined range centered on Vc * R2 / (R1 + R2), it is detected that the first relay 31 and the second relay 32 are in an off state, When it exceeds the predetermined range, it is detected that either the first relay 31 or the second relay 32 is in the on state.

  Immediately after the ignition switch 8 is turned on, the first relay 31 and the second relay 32 should be in an off state, as will be described later. When it is detected that one of the relays 32 is in the on state, the controller 7 determines that an abnormality (relay stuck) has occurred in one of the relays and prohibits switching of the drive mode. .

Therefore, in such a case, even if the driver operates the drive mode changeover switch and selects a drive mode different from the current one, the controller 7 does not output a drive signal to the current control circuit 2 and the motor forward / reverse circuit 3, The currently set drive mode is maintained as it is.
On the other hand, when the motor forward / reverse rotation check circuit 4 detects that the first relay 31 and the second relay 32 are in the OFF state, the controller 7 determines that there is no abnormality. In such a case, the controller 7 permits the switching of the drive mode, and outputs a drive signal corresponding to the operation signal from the drive mode changeover switch to the current control circuit 2 and the motor forward / reverse circuit 3 to enter the selected drive mode. Switch.

  For example, when the 4H mode is selected when the current drive mode is the 2WD mode, the controller 7 outputs a drive signal to the first output processing circuit 33, energizes the first relay coil 34, and the first relay 31. Is turned on, and a drive signal is output to the current control circuit 2 to supply a predetermined drive current to the motor M. As a result, the motor M is rotated forward and rotated to a position corresponding to the 4H mode. When the transfer device is switched to the 4H mode, the supply of the drive current to the motor M is stopped and the first relay 31 is turned off to stop the motor M (the motor M is stopped at a position corresponding to the 4H mode). Stop).

When the 4L mode is selected, the motor M is further rotated in the forward direction to rotate to a position corresponding to the 4L mode, and when the transfer device is switched to the 4L mode, the supply of the drive current to the motor M is stopped. At the same time, the first relay 31 is returned to the off state (the motor M is stopped at a position corresponding to the 4L mode).
If the 2WD mode is selected when the current drive mode is the 4H mode, the controller 7 outputs a drive signal to the second output processing circuit 35, energizes the second relay coil 36, and the first relay 32. Is turned on, and a drive signal is output to the current control circuit 2 to supply a predetermined drive current to the motor M. As a result, the motor M is rotated in the reverse direction and rotated to the position corresponding to the 2WD mode. When the transfer device is switched to the 2WD mode, the current supply to the motor M is stopped and the second relay 32 is returned to the OFF state to stop the motor M (the motor M is stopped at a position corresponding to the 2WD mode). ).

  When the motor M is driven, the controller 7 outputs a drive signal (that is, a forward drive command or a reverse drive command to the motor M) output to the motor forward / reverse circuit 3 and a motor forward / reverse drive check circuit. 5 is compared with the determination result (actual driving direction of the motor M) to determine whether the motor drive circuit is abnormal. This prevents the motor M from rotating in an unexpected direction due to an abnormality that occurs during driving of the motor M, and the abnormality in which the first relay 31 and the second relay 32 do not operate in an off state (the motor M does not drive). (Abnormality) can also be detected.

  As described above, according to the motor drive circuit according to the present embodiment, the state of the first relay 31 and the second relay 32 can be detected without the motor M being driven by the motor forward / reverse rotation check circuit 4. Then, by comparing this detection result with the set relay status, it is possible to determine in advance (before driving the motor M) whether or not there is a relay abnormality (relay stuck). By prohibiting switching (supply of drive current to the motor M), it is possible to reliably prevent the motor M from operating without permission. Further, when the motor M is being driven, it is possible to determine whether or not the motor drive circuit is abnormal based on the determination result by the motor forward / reverse rotation drive check circuit 5.

It is a block diagram of the motor drive circuit which concerns on embodiment. It is a figure which shows a part of structure of the motor forward / reverse rotation check circuit which concerns on embodiment. It is a figure which shows the conventional motor drive circuit.

Explanation of symbols

      DESCRIPTION OF SYMBOLS 1 ... Motor drive circuit, 2 ... Current control circuit (current supply means) 3 ... Motor forward / reverse rotation circuit, 4 ... Motor forward / reverse rotation check circuit (relay state detection means), 7 ... Controller (relay drive means, abnormality determination means), 31 ... 1st relay, 32 ... 2nd relay

Claims (3)

Two relays and relay driving means for driving the two relays on and off, respectively, and driving the motor in the forward direction by setting one of the relays to the on state and the other relay to the off state. A motor drive circuit for reverse driving,
Current supply means for supplying a drive current to the motor based on a drive signal;
Relay state detection means for detecting the state of the two relays in a state where the supply of drive current to the motor is stopped;
An abnormality determining means for comparing the state of the relay set by the relay driving means and the state of the relay detected by the relay state detecting means to determine whether there is an abnormality in the motor drive circuit;
A motor drive circuit comprising: The relay driving means turns off the two relays when supply of driving current to the motor is stopped,
3. The motor drive according to claim 1, wherein the abnormality determination unit determines that there is an abnormality when the relay state detection unit detects that any one of the relays is in an on state. circuit.   3. The motor drive circuit according to claim 1, wherein the abnormality determination unit prohibits supply of a drive current to the motor when it is determined that there is an abnormality.

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