JP2009213234A - Motor controller - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a motor controller capable of suppressing power consumption of a battery and further preventing breakdown of ECU, due to reverse electromotive power of a motor. <P>SOLUTION: A relay having two contact points, i.e. normally open and normally closed types is used, and the connection destination of the normal close side is connected to a gate terminal portion of a motor drive circuit portion via a resistance (Fig.1). When the ECU is brought into a standby mode and the relay is turned OFF, a voltage is generated in the motor drive circuit by a reverse electromotive force due to an external force generated from the motor, the motor drive circuit is turned ON by the voltage and the reverse electromotive force is returned as a current to the motor; and by doing so, a large part of surge energy is consumed in the motor. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a motor control device, and more particularly to a seat belt retractor motor control device.

  2. Description of the Related Art Conventionally, a motor control ECU mounted on a vehicle has a structure in which a back electromotive force surge from a motor is released to a power source side by maintaining the power switch conduction of a motor drive circuit (Patent Document 1).

  In the above-described conventional device, it is necessary to maintain the switch conduction of the power supply circuit. Like a seat belt motor control ECU with an occupant fitting function, even if the vehicle is in an ignition-off state, it may be operated by the vehicle battery, and in order to avoid wasting battery power after a certain period of time In the case of an ECU that reduces power consumption depending on the mode, there is a possibility that the ECU will be destroyed by the back electromotive force of the motor when the motor is rotated by an external force in a state where power cannot be supplied to the motor drive circuit in the standby mode. There is.

JP-A-8-308004

  The problem to be solved by the present invention is to suppress the consumption of battery power and further to prevent the destruction of the ECU due to the motor back electromotive force.

  Accordingly, in the present invention, a plurality of switching elements that convert a direct current into an alternating current and output the alternating current to the motor, a drive signal is output to the plurality of switching elements, and the plurality of switching elements are driven. A control circuit unit that controls the motor, wherein the plurality of switching elements provide a motor control device that is driven based on a current caused by a counter electromotive force generated by rotation of the motor.

  Consumption of battery power can be suppressed, and further, destruction of the ECU due to motor back electromotive force can be prevented.

  Using a relay with two contacts, normally open and normally closed, the connection on the normally closed side is connected to the gate terminal of the motor drive circuit through a resistor (Fig. 1). When the ECU enters the standby mode and the relay is OFF, a voltage is generated at the gate terminal of the motor drive circuit by the back electromotive force generated by the external force generated from the motor. By returning electric power to the motor as current, most of the surge energy is consumed by the motor, so that the motor drive circuit is not destroyed by the surge energy.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

  First, the configuration of the vehicle collision safety device using the seat belt retractor according to the present embodiment will be described with reference to FIG.

  FIG. 15 is a perspective view showing a configuration of a vehicle collision safety device using a seat belt retractor according to an embodiment of the present invention.

  An obstacle sensor 102 that outputs a signal corresponding to the distance to the obstacle is attached to the front portion of the vehicle 112. The output signal of the obstacle sensor 102 is transmitted to the collision determination controller 106 that is electrically connected to the obstacle sensor 102. A signal from the wheel speed sensor 104 that outputs a signal corresponding to the speed of the vehicle is also transmitted to the collision determination controller 106 that is electrically connected to the wheel speed sensor 104.

  The collision determination controller 106 determines whether or not the vehicle 112 collides with an obstacle based on signals from the obstacle sensor 102 and the wheel speed sensor 104. For example, when the distance to the obstacle obtained from the output signal of the obstacle sensor 102 is shorter than a predetermined value and the vehicle speed obtained from the output signal of the wheel speed sensor 104 is higher than the predetermined value, The collision determination controller 106 determines that the vehicle 112 collides with an obstacle. When the collision determination controller 106 determines that it collides with an obstacle, it outputs a command signal to the brake assist device 108 and the electromechanical integrated seat belt retractor 100 before the vehicle 112 collides with the obstacle.

  The brake assist device 108 and the electromechanical integrated seat belt retractor 100 are electrically connected to the collision determination controller 106. The brake assist device 108 applies a brake based on a command signal from the collision determination controller 106, for example. Further, the electromechanically integrated seat belt retractor 100 winds up the seat belt, for example, based on a command signal from the collision determination controller 106.

  FIG. 2 is a schematic configuration of a seat belt system using the present invention.

  In this system, the control device 22 drives and controls the motor 321 to wind up the seat belt 20. The seat belt is retracted by increasing the restraining force in an emergency for the purpose of safety of the occupant 23, automatic fitting when attached to the buckle 25 for the purpose of improving the comfort of the occupant 23, and improving the appearance of the vehicle. And automatically storing the seat belt 20 in the retractor 24 for the purpose.

  Next, the configuration of the seat belt retractor according to the present embodiment will be described with reference to FIG.

  FIG. 16 is an exploded perspective view showing the configuration of the seat belt retractor according to one embodiment of the present invention.

  A spool 200 for winding the seat belt 20 (shown in FIG. 2) and a frame 202 for holding the spool 200 in the axial direction are attached to the electromechanically integrated seat belt retractor 100. The frame 202 is provided with a lock mechanism 204 that locks the seat belt 20 from being released from the spool 202 in an emergency. The lock mechanism 204 is provided with a speed detection unit 206 that detects the rotational speed of the spool 202 and activates the lock mechanism 204.

  Further, a pretensioner portion 214 and a return spring 216 are located on the opposite side of the spool 200 from the lock mechanism 202. The rotation shaft of the return spring 216 is configured to rotate in synchronization with the rotation shaft of the spool 200. Between the motor 208 and the spool 200, a motor power transmission mechanism 218 that transmits the rotational force of the motor 208 to the spool 200 is provided. The motor power transmission mechanism 218 is formed by a plurality of spur gears. A motor gear 210 fixed to the output shaft of the motor 208 is engaged with a spur gear of the motor power transmission mechanism 218.

  The control circuit board 314 is arranged at a position parallel to the rotation surface of the spool 200. The control circuit board 314 includes a microcomputer 349 capable of 8-bit or 16-bit calculation, a motor drive circuit 344 that supplies power to the motor 208 via the motor terminal 212, and a nonvolatile memory 408. Has been. A vehicle connector 220 is mounted on the control circuit board 314, and plays a role of supplying power from the battery to the control circuit board and inputting a command signal from the collision determination controller 106. Further, a current sensor 412 that detects a current flowing through the motor 208 is provided on the control circuit board 314.

  For electrical connection between the control circuit board 314 and the motor 208, a method of fixing the wire to the control circuit board 314 and the motor terminal 212 with solder or a relay terminal having both ends formed into a female shape is used. A method of connecting without using the is used. In order to suppress electrical noise generated from the motor 208, it is useful to shorten the wiring length between the control circuit board 314 and the motor 208. For this purpose, a method using a relay terminal is preferable. The cover 222 is arranged outside the control circuit board 314 in order to protect the control circuit board 314 from disturbance such as water droplets.

  The internal circuit configuration of the control device 22 in this embodiment is shown in FIG.

  Based on various actuators such as the buckle switch 341 and the brake stroke sensor 342 or data transmitted from the CANBUS communication 351, the control device 22 drives the motor 321 as necessary to perform the seat belt winding operation.

  The motor drive circuit 344 in this embodiment is an H bridge circuit including four transistors, that is, high-side transistors 305 and 306 and low-side transistors 307 and 308, and is controlled by the microcomputer 349. A relay 343 having a three-point structure having a normally open contact 355, a normally closed contact 353 and a connection destination common contact 356 is disposed between the motor drive circuit 344 and the drive system power supply.

  The relay 343 is in an OFF state when power is not supplied to the control device 22 or when the coil 354 inside the relay 343 is not conductive, and the connection destination common contact 356 is connected to the normal close contact 353, The normally open contact 355 is not connected. When the transistor 358 controlled by the microcomputer 349 is turned on, the coil 354 inside the relay 343 is turned on, and the relay internal movable part spring 357 is expanded by the attractive force of the coil 354, so that the connection destination common contact 356 and the normal open contact 355 is connected, the relay 343 is turned on, and power is supplied to the motor drive circuit 344. At the same time, the connection destination common contact 356 and the normal close contact 353 are disconnected.

  After power is supplied to the motor drive circuit 344, the microcomputer 349 controls the rotation of the motor 321 by motor drive signals INA, INB, ENA, ENB, and PWM. Table 1 shows how the states of the high-side transistors 305 and 306 and the low-side transistors 307 and 308 change according to the motor driving signals INA, INB, ENA, ENB, and PWM.

  For example, FIG. 4 shows an operation in the case where the motor is rotated in the forward rotation direction according to the truth table of Table 1. When INA = High, INB = Low, ENA = High, ENB = High, the high-side transistor 305 is ON, the high-side transistor 306 is OFF, the low-side transistor 307 is OFF, and the low-side transistor 308 is in accordance with PWM logic. Repeat ON and OFF. When the low-side transistor 308 is repeatedly turned on and off, the current 401 flows through the motor 321 through the body diode 310 of the low-side transistor 308 or the high-side transistor 306, so that the motor 321 rotates in the forward direction.

  FIG. 5 shows the operation when the motor is rotated in the reverse direction according to the truth table of Table 1. When INA = Low, INB = High, ENA = High, ENB = High, the high-side transistor 305 is OFF, the high-side transistor 306 is ON, the low-side transistor 308 is OFF, and the low-side transistor 307 is in accordance with PWM logic. Repeat ON and OFF. When the low-side transistor 307 is repeatedly turned on and off, the current 501 flows through the motor 321 through the body diode 309 of the low-side transistor 307 or the high-side transistor 305, so that the motor 321 rotates in the forward direction.

  FIG. 6 shows an operation in the truth table of Table 1 when the motor is stopped in the brake mode. FIG. 6 shows a case where the brake mode is stopped when the motor 321 is rotating in the reverse direction. Even when the motor 321 is rotating in the forward direction, only the current direction is reversed and the same. . When INA = High, INB = High, ENA = High, ENB = High, the high-side transistors 305 and 306 are turned on and the low-side transistors 307 and 308 are turned off. At this time, when no power is supplied from the motor drive circuit 344 side and no rotational force is applied by an external force or inertial force, the motor 321 does not rotate, but when it is rotated by an external force or inertial force, the counter electromotive force 601 is rotated. Is generated. A current 603 is generated by the counter electromotive force. The current 603 is returned to the motor 321 via the body diode 309 of the high side transistor 305 and the high side transistor 306. Since this current generates a magnetic field opposite to the magnetic field in the motor 321, the current is in a direction that prevents the motor 321 from rotating, and cancels external force and inertial force. For this reason, it is possible to brake the rotation of the motor 321 as a brake mode.

  In the truth table of Table 1, when INA = Low, INB = Low, ENA = High, ENB = High, only when the logic of PWM becomes High, the current is supplied to the motor 321 through the path 701 shown in FIG. However, if the microcomputer 349 does not drive the motor 321 or if no power is supplied to the microcomputer 349, the PWM logic is normally at the low level, so this brake mode is used. do not do.

  In the automatic fitting when attaching to the buckle 25 for the purpose of improving comfort or the automatic retracting of the seat belt 20 to the retractor 24 for the purpose of improving the appearance of the vehicle, the motor 321 is rotated and the seat belt 20 is wound up. However, at this time, when the occupant 23 keeps pulling the seat belt 20 against the operation of winding up by a deliberate operation, the motor 321 rotates in the reverse direction to generate a counter electromotive force. If there is no path for escaping the counter electromotive force, excessive back electromotive force is applied to the high-side transistor 305 and the low-side transistor 308, and these transistors are destroyed.

  When the vehicle is in an ignition-on state and a power generator such as an alternator is operating, the control device 22 continues to conduct the relay 343 without needing to limit the power, so that a surge current caused by the back electromotive force 802 as shown in FIG. Can be escaped to the drive system power supply side through the path 801.

  The automatic fitting operation and the automatic storage operation are performed by the electric power from the vehicle battery when the vehicle is in the ignition off state. In this case, since it is inconvenient for the vehicle system to continue the conduction of the relay 343 and consume battery power, the control device 22 turns off the conduction of the relay 343 after the automatic fitting operation or the automatic storage operation is completed. In this case, as shown in FIG. 9, since the surge current due to the back electromotive force 902 flows through the path 901, a voltage is generated at the normally closed contact 353 of the relay 343. In this embodiment, when this voltage is generated, the motor drive signals INA, INB, ENA, and ENB can be set to a high level by the back electromotive force surge absorption path generation circuit 347, so that the motor 321 is prevented from rotating by the brake mode. It is done. That is, the motor drive circuit 344 (a plurality of switching elements) is driven based on a current due to the counter electromotive force generated by the rotation of the motor 321 independently of the control by the microcomputer 349 (control circuit unit). Thereby, the surge current due to the back electromotive force is released through the path 903 during the brake mode, so that the high-side transistor 305 and the low-side transistor 308 are not destroyed.

  Further, when the vehicle is not operated for a long period of time, the control device 22 detects that a signal from the CANBUS communication line 351 or the like is not sent to suppress the power consumption of the battery, and the power supply IC (361 ) Enters a standby mode in which almost no power is consumed by stopping the power supply to the microcomputer 349 or setting the microcomputer 349 in a low power consumption mode. In this case as well, even if a back electromotive force is generated as in FIG. 9, the motor 321 enters the brake mode by the surge absorption path generation circuit 347, so that the high side transistor 305 and the low side transistor 308 are not destroyed.

  That is, even when the ECU is in the standby mode and the power switch conduction of the motor drive circuit cannot be maintained, the motor drive circuit can be protected from a surge caused by the back electromotive force. In addition, the control device does not need to maintain the power switch continuity in preparation for the occurrence of a back electromotive force surge.

  As shown in FIG. 3, the surge absorption path generation circuit 347 can achieve only a simple configuration in which the relay normal close contact 353 and the motor driving signals INA, INB, ENA, ENB are connected via the resistor 313.

  As shown in FIG. 8, when the relay 343 is conductive and the relay connection destination common contact 356 and the relay normal open contact 355 are connected, the motor driving signals INA, INB, ENA, ENB are passed through the resistor 313 and the resistor 348. Is pulled down to GND. By setting the value of the series resistance 315 between the microcomputer 349 and the motor drive circuit 344 to be lower than the resistance 313, the control logic of the microcomputer 349 is transmitted to the motor drive circuit 344.

  As shown in FIG. 9, when the relay 343 is turned off and the relay connection destination common contact 356 and the relay normal close contact 353 are connected, the resistor 313 functions as the surge absorption path generation circuit 347. When a surge voltage due to the back electromotive force is generated at the relay normal close contact 353, the motor drive signals INA, INB, ENA, and ENB cause the gate side terminal 316 of the motor control circuit 344 to be at a high level by a part of the power. At this time, if the amount of current flowing into the terminal 316 is too large, the high-side transistors 305 and 306 and the low-side transistors 307 and 308 are destroyed. Therefore, the resistor 313 has a resistance value of about several tens of KΩ as a current limiting resistor.

  The resistor 348 connected to the relay normal close contact 353 can function as a discharge resistor in addition to the function of pulling down the resistor 313 of the surge absorption path generation circuit 347 to GND when the relay 343 is conductive. When the relay 343 is turned from ON to OFF, the electric charge of the capacitor 346 upstream of the motor drive circuit 344 is discharged.

  In the present embodiment, specifically, 51 KΩ is used as the resistor 313 of the surge absorption path generation circuit 347, 15 KΩ is used as the series resistance 315 between the microcomputer 349 and the motor drive circuit 344, and 330Ω is used as the discharge resistance 348.

  In this embodiment, since the current required for driving the motor 321 is large, the relay 343 is used as the switching means of the drive system power supply for the purpose of ensuring reliability. However, a semiconductor element such as a power transistor can be substituted. It is. In this case, a circuit configuration is required to prevent a large current from flowing into the parasitic diode of the semiconductor element when the battery is reversely connected.

  When the relay 343 is replaced with a semiconductor element, two power transistors or the like may be combined to switch each other in a toggle manner.

  FIG. 10 shows the configuration of the motor control circuit 1000 in the second embodiment. In this embodiment, when the relay 1001 is turned off and the relay common connection destination contact 1003 is connected to the normally closed contact 1002, the surge current generated by the back electromotive force generated from the motor 1004 passes through the path 1005 and passes through the relay 1001. It is released to GND through a Zener diode 1006 connected to the normally closed contact 1002. In this embodiment, it is necessary to have a power withstand enough to allow a surge current due to the back electromotive force to flow through the Zener diode 1006.

  FIG. 11 shows the configuration of the motor control circuit 1100 according to the third embodiment. The normally closed contact 1102 of the relay 1101 is directly connected to GND without a resistor. In this embodiment, when the relay 1101 is turned off and the relay common connection destination contact 1103 is connected to the normally closed contact 1102, the surge current generated by the back electromotive force generated from the motor 1104 passes through the path 1105 to the GND. And escaped. In this embodiment, when the harness and pattern at both ends of the motor are short-circuited to the power supply side, if the relay 1101 is turned off, a dead short occurs between the power supply and GND. It is necessary not to short-circuit to the side.

  FIG. 12 shows a configuration of a motor control circuit 1200 according to the fourth embodiment. A normally closed contact 1202 of a relay 1201 is connected to a motor end 1207 via a diode 1206. In this embodiment, when the relay 1201 is turned off and the relay common connection destination contact 1203 is connected to the normally closed contact 1202, the surge current generated by the back electromotive force generated from the motor 1204 passes through the path 1205 to the motor 1204. Therefore, there is no destruction of the motor control circuit 1200. In this embodiment, it is necessary to have a power withstand enough to allow a back electromotive force surge current to flow through the diode 1206.

  FIG. 13 shows the configuration of the motor control circuit 1300 in the fifth embodiment. The normally closed contact 1302 of the relay 1301 is directly connected to the motor end 1307. In this embodiment, when the relay 1301 is turned off and the relay common connection contact 1303 is connected to the normally closed contact 1302, the surge current caused by the counter electromotive force generated from the motor 1304 is returned to the motor 1304 through the path 1305. Therefore, the motor control circuit 1300 is not destroyed. In this embodiment, when the charge of the downstream capacitor 1308 of the relay 1301 is discharged, the low-side transistor 308 needs to be separately controlled.

  FIG. 14 shows the configuration of the motor control circuit 1400 in the sixth embodiment, and the normally closed contact 1402 of the relay 1401 is directly connected to the motor end 1407. In this embodiment, when the relay 1401 is turned off and the relay common connection destination contact 1403 is connected to the normally closed contact 1402, the surge current caused by the counter electromotive force generated from the motor 1404 is returned to the motor 1405 through the path 1405. Therefore, the motor control circuit 1400 is not destroyed. In this embodiment, since the voltage at the motor end 1407 is close to the GND level due to the discharge resistor 1406, the method of monitoring the voltage at the motor end 1407 cannot be used as means for detecting the OPEN or GND short of the motor terminal. Used when it is not necessary to monitor the end voltage.

It is an internal circuit structure of the motor control apparatus by a prior art. It is an internal circuit structure of the motor control apparatus by this invention. 1 is a seat belt system according to an embodiment of the present invention. It is a figure which shows the control state when rotating the motor of the seatbelt concerning the form of Example 1 to a normal rotation direction. It is a figure which shows the control state when rotating the motor of the seatbelt concerning the form of Example 1 to a reverse rotation direction. It is a figure which shows the control state when making the motor of the seatbelt concerning the form of Example 1 into a brake mode. It is a figure which shows the control state when making the motor of the seatbelt concerning the form of Example 1 into a brake mode. It is a figure which shows the path | route which releases the surge electric current by the back electromotive force generated from the motor of the seatbelt concerning the form of Example 1. FIG. It is a figure which shows the path | route which releases the surge electric current by the back electromotive force generated from the motor of the seatbelt concerning the form of Example 1. FIG. 3 is an internal circuit configuration of a motor control device according to a form of Example 2; 6 is an internal circuit configuration of a motor control device according to a form of Example 3; 6 is an internal circuit configuration of a motor control device according to a form of Example 4; 9 is an internal circuit configuration of a motor control device according to a form of Example 5; 9 is an internal circuit configuration of a motor control device according to a form of Example 6; It is a lineblock diagram of the collision safety device of vehicles using the seatbelt retractor concerning this embodiment. It is a disassembled perspective view of an electromechanical integrated seat belt retractor.

Explanation of symbols

20 seat belt 22 control device 23 occupant 24 retractor 25 buckle 100 electromechanically integrated seat belt retractor 102 obstacle sensor 104 wheel speed sensor 106 collision determination controller 108 brake assist device 112 vehicle 305, 306 high side transistors 307, 308 low side Side transistor 313, 348 Resistor 321 Motor 343 Relay 344 Motor drive circuit 349 Microcomputer

Claims (11)

A motor control device for controlling a seat belt retractor motor,
A plurality of switching elements for converting a direct current into an alternating current and outputting the alternating current to the motor;
A control circuit unit that outputs a drive signal to the plurality of switching elements and controls driving of the plurality of switching elements, and
The plurality of switching elements are driven by a motor control device independently of the control by the control circuit unit and based on a current caused by a counter electromotive force generated by rotation of the motor. The motor control device according to claim 1,
The plurality of switching elements are driven to be in a brake mode that prevents rotation of the motor based on a current caused by a counter electromotive force generated by rotation of the motor, independently of control by the control circuit unit. Control device. The motor control device according to claim 1,
The plurality of switching elements constitutes an inverter circuit unit including a plurality of high-side switching elements and low-side switching elements,
The inverter circuit unit drives the plurality of high-side switching elements in an on state and the plurality of low-side switching elements in an off state based on a current due to a counter electromotive force generated by rotation of the motor. Control device. The motor control device according to claim 1,
The control circuit unit includes a microcomputer for controlling the drive circuit based on information output from at least one of a vehicle communication interface circuit, a switch for detecting states of various actuators, or sensors. apparatus. The motor control device according to claim 1,
Relay means capable of connecting or disconnecting an electrical connection between the plurality of switching elements and an external power source;
When the electrical connection between the plurality of switching elements and an external power source is interrupted by the relay means, the plurality of switching elements are generated by the rotation of the motor independently of the control by the control circuit unit. A motor control device that is driven based on the current generated by the back electromotive force. The motor control device according to claim 5,
The relay means includes two contacts, and the connection state of the contacts can be switched by electromagnetic force of a built-in coil,
One contact side of the two contacts is electrically connected to the external power source,
The other contact side is a motor control device that is grounded to the vehicle body via discharge resistance means. The motor control device according to any one of claims 1 to 6,
The plurality of switching elements are a plurality of transistors,
A motor control device in which a current caused by the back electromotive force is input to gate terminals of the plurality of transistors via a first resistance means. The motor control device according to claim 7,
The control circuit unit and the plurality of transistors are connected via second resistance means,
The motor control device, wherein a resistance value of the second resistance means is set smaller than a resistance value of the first resistance means. The motor control device according to any one of claims 1 to 6,
The control circuit unit has a standby mode for monitoring signal input from the outside without controlling the switching operation of the plurality of switching elements,
When the control circuit unit is in the standby mode, the plurality of switching elements are driven based on a current caused by a counter electromotive force generated by rotation of the motor, independently of the control by the control circuit unit. Motor control device. A drive circuit composed of a plurality of switching elements for driving a vehicle seat belt retractor motor;
Relay means capable of connecting or disconnecting the electrical connection between the drive circuit and an external power source by a switching operation;
At least one switch or sensor for detecting the state of the vehicle communication interface circuit and various actuators is provided, and the microcomputer has a microcomputer for controlling the drive circuit and the relay according to the state of the interface circuit, various actuators, switches, and sensors. A control circuit;
In the motor control device with
The relay has a two-contact structure, the motor drive circuit is connected to the normally closed side via a resistor, the power supply for driving the motor is connected to the normally open side, and the relay is connected to the normally closed side. The motor control device according to claim 1, wherein when the motor generates a counter electromotive force by an external force, the drive circuit shifts to a brake mode for regenerating the counter electromotive force to the motor. The motor control device according to claim 10,
A motor control device having a standby mode for reducing power consumption as much as possible, monitoring only a state change of a switch or an interface circuit during the standby mode, and not operating a drive circuit or a control circuit.

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