JP2014034221A - Motor control device, and sheet belt device - Google Patents

Abstract

There is provided a motor control device capable of preventing an increase in dark current even when a switching element constituting a motor drive circuit fails without adding a component such as a relay.
A motor drive unit for driving a motor, a motor drive driver unit for generating a PWM signal for driving the motor drive unit, and a potential for fixing the potential to turn off the motor drive unit at low current consumption. A fixing unit 320; a motor voltage detection unit 314 that detects a voltage applied to a terminal of the motor; an A / D conversion unit 318a that performs A / D conversion on a voltage signal detected by the motor voltage detection unit; A CPU 308 serving as an abnormality determining unit that determines whether or not the potential fixing unit is normal based on the voltage signal A / D-converted by the conversion unit. If the abnormality determining unit determines that there is an abnormality, the potential fixing unit 320 fixes the potential to the motor driver 310 off.
[Selection] Figure 3

Description

  The present invention relates to a motor control device, for example, a motor control device optimal for a seat belt retractor, and a seat belt device for winding a seat belt using the motor control device.

  2. Description of the Related Art Conventionally, a control device for driving this type of motor controls the supply of drive current to the motor by controlling conduction of a plurality of switching elements constituting the bridge circuit based on a switching command signal given from the control means. Signal detection for detecting a first diagnostic signal output to one terminal of the motor and a second diagnostic signal output to the other terminal of the motor. And a current supply means for selectively supplying a diagnostic current to the bridge circuit at the time of failure diagnosis of the switching element when the motor is stopped, and the control means selects a plurality of switching elements at the time of failure diagnosis of the switching element. The first diagnostic signal and the second diagnostic signal detected by the signal detection means as a result, and the input first diagnostic signal and Detecting the rising / falling of the second diagnostic signal is for diagnosing faults of at least a switching element on the basis of the detection result (for example, see Patent Document 1).

JP 2008-187873 A

  When a motor control device (ECU) as described in Patent Document 1 is mounted on a vehicle, in order to reduce the power consumption of the ECU, for example, the ignition key is off and no wake-up factor is input for a set time or longer. With such a condition, the ECU enters a low current consumption state when the sleep condition is satisfied.

  When the current consumption is low, it is necessary to fix the switching elements that make up the motor drive circuit, such as the motor driver IC and H-bridge. However, if the location fails, the switching elements are fixed off when the current consumption is low. In the case of a system that cannot be physically cut off from the power source, dark current increases, so it is necessary to add a component such as a relay.

  The present invention has been made in view of such a problem, and the purpose thereof is to add a component such as a relay and even when a switching element constituting the motor drive circuit fails, An object of the present invention is to provide a motor control device capable of preventing an increase in dark current and a seat belt device using the motor control device.

  In order to achieve the above object, a motor control device according to the present invention includes a motor drive unit that drives a motor, a motor drive driver unit that generates a PWM signal that drives the motor drive unit, and a low current consumption. A potential fixing unit that fixes a potential so as to turn off the motor driving unit, a motor voltage detection unit that detects a voltage applied to a terminal of the motor, and a voltage signal detected by the motor voltage detection unit is A / D An A / D conversion unit for conversion, and an abnormality determination unit for determining whether or not the potential fixing unit is normal based on the voltage signal A / D converted by the A / D conversion unit, the abnormality determination When it is determined as abnormal by the means, the potential fixing unit fixes the potential to the motor driving unit off.

  According to the present invention, it is possible to detect a failure of a motor driver IC or an off-fixing circuit of a switching element constituting an H-bridge at low current consumption at an appropriate timing, and a highly reliable motor control device, particularly a seat belt retractor. Motor control device can be provided. Further, according to the present invention, it is possible to prevent an increase in dark current even in the case of a system that does not have a relay or the like and cannot be physically cut off from the power supply.

It is a safety device connection diagram including a seat belt device in a vehicle according to the present invention. It is a passenger | crew restraint figure to the seat by the seatbelt apparatus which concerns on this invention. It is a block diagram of a motor control device concerning the present invention. It is a control circuit diagram in Example 1 concerning the present invention. It is a wave form chart at the time of failure detection concerning the present invention. It is a control flow figure concerning the present invention. It is a control circuit diagram in Example 2 concerning the present invention.

  Hereinafter, an embodiment in which a motor control device according to the present invention is mounted on a vehicle will be described in detail with reference to the drawings.

[Example 1]
FIG. 1 is a layout diagram of a collision determination unit and a seat belt device in a vehicle using the motor control device according to the first embodiment. First, in FIG. 1, a vehicle 112 includes various sensors such as an obstacle sensor 102 and a wheel speed sensor 104 and a collision determination controller 106 as collision determination means. An obstacle sensor 102 that outputs a signal corresponding to the distance to the obstacle is attached to the front part of the vehicle. 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, and outputs a command signal to the brake assist device 108 and the retractor 100 before the vehicle 112 collides with the obstacle.

  The brake assist device 108 and the seat belt drive controller 110 are electrically connected to the collision determination controller 106, and each execute a predetermined operation based on a command signal from the collision determination controller 106.

  FIG. 2 shows a seat belt device. The retractor 100 includes a motor 200, and the seat belt can be wound by rotating the motor 200. Here, the motor may be a direct current motor or a brushless motor. For example, consider a case where the occupant 202 is driving the vehicle 112 and the occupant 202 moves to the front of the vehicle although it is minute, and a gap is generated between the occupant 202 and the seat 204. In FIG. 1, the seat belt device is attached to the passenger seat side seat, but the same seat belt device is also attached to the driver seat side seat.

  In such a situation, when the vehicle 112 collides with an obstacle, the occupant is not restrained by the seat 204 and is strongly hit against the seat 204. However, according to the motor control apparatus of the first embodiment, the motor 200 included in the retractor 100 winds up the seat belt 206 before the vehicle 112 and the obstacle collide, and the gap between the passenger 202 and the seat 204 is taken up. Can be eliminated. Accordingly, when the vehicle 112 and the obstacle collide, the passenger 202 is already restrained by the seat 204, so that the impact on the passenger 202 can be reduced.

  By the driving of the motor 200 controlled by the seat belt drive controller 110, the retractor 100 performs pre-crash operation of the occupant 202, automatic fitting for the purpose of improving comfort or automatic storage of the seat belt 206, and calls the occupant 202 for attention. Winding such as a warning operation is performed. The seat belt device according to the present invention is configured to wind the seat belt 206 with the motor 200 using the motor control device of the first embodiment.

  FIG. 3 schematically shows the configuration of the motor control device for the seat belt retractor. When the battery and the power (VB) 300 supplied from the alternator driven by the engine are supplied to the custom IC 304 in the motor control unit (ECU) 302 for the seat belt retractor, the vehicle is connected to the power circuit 306 in the custom IC 304. Battery voltage is supplied. The power supply circuit 306 generates a positive power supply voltage (VCC = 5V) to be supplied to a signal system element such as a central processing unit 308 (hereinafter referred to as a CPU) that controls signal processing. The power supply circuit 306 has a function of receiving a periodic signal from the CPU 308 and monitoring the operation of the CPU 308 and a function of resetting the CPU 308.

  The motor control unit (ECU) 302 has a motor drive unit 310 for driving the motor 200. The motor driving unit 310 is constituted by an H bridge circuit using a MOSFET, for example. The motor drive driver 312 in the custom IC 304 is controlled by a signal from the CPU 308 to generate a PWM signal for driving the motor drive 310. The motor driving unit 310 is operated by the PWM signal and supplies electric power to the motor 200.

  The motor voltage detection unit 314 receives the voltage at both ends of the motor 200 and outputs a voltage according to normal or abnormal conditions. The voltage output from the motor voltage detection unit 314 is input to the A / D conversion unit 318a in the custom IC 304.

  The current detection unit 316 detects a current flowing through the motor, and after voltage conversion and amplification, the current detection unit 316 inputs the current to the A / D converter 318b in the custom IC 304. The A / D converters 318a and 318b are connected to the CPU 308. The motor control unit (ECU) 302 can comfortably perform operations such as storing the seat belt based on the current detected by the current detection unit 316.

  A potential fixing unit 320 is provided between the motor driving unit 310 and the motor driving driver unit. The potential fixing unit 320 is connected to the power supply 300 or GND via a switch, for example, and fixes the gate potential of the MOSFET of the motor driving unit 310 to off at the time of low current consumption that transitions when the sleep condition is satisfied. Further, the potential fixing unit 320 can also be controlled from the CPU 308. Here, the power supply circuit 306, the motor drive driver unit 312 and the like in the custom IC 304 may be configured with external components.

  FIG. 4 is a circuit diagram illustrating in detail the motor driving unit 310, the motor driving driver unit 312, the motor voltage detecting unit 314, and the potential fixing unit 320 used in this embodiment.

  The motor driving unit 310 is configured by an H bridge using four MOSFETs (400a, 400b, 400c, 400d). In order to drive the motor, the CPU 308 gives a signal to the motor drive driver unit 312 according to the drive mode. The motor drive driver unit 312 generates a PWM signal, controls the gate voltage of the MOSFETs (400a, 400b, 400c, 400d), switches the MOSFET, and supplies power to the motor 200. Here, the Pch MOSFET connected to the high side can be replaced by an Nch MOSFET depending on, for example, a drive circuit having a booster circuit.

  The motor drive driver unit 312 acts on each of the four MOSFETs (400a, 400b, 400c, 400d). For example, the motor drive driver unit 312 includes MOSFETs 408a and 408b for the MOSFET 400a. MOSFET 408a is disposed between power supply 300 and MOSFET 400a, and MOSFET 408b is disposed between GND and MOSFET 400a.

  The motor drive driver unit 312 includes, for example, MOSFETs 408c and 408d for the MOSFET 400c. The MOSFET 408c is disposed between the power source 300 and the MOSFET 400c, and the MOSFET 408d is disposed between the GND and the MOSFET 400c. Further, by giving a signal that turns off both the MOSFETs (408a, 408b) and the MOSFETs (408c, 408d), the gate voltages of the MOSFETs (400a, 400c) become indeterminate, which is similar to the low current consumption state. High impedance state. Although not shown directly in FIG. 4, the same circuit connection as described above is also configured for the MOSFETs (400c, 400d). With the above configuration, the motor drive driver unit 312 generates a PWM signal for driving the motor drive unit 310.

  The motor voltage detection unit 314 includes a pull-up resistor 402 connected between the drain terminal portions of the MOSFETs 400a and 400c and VCC, and a pull-down resistor 404 connected between the drain terminal portions of the MOSFETs 400b and 400d and GND. Further, a diode 406 for suppressing a current flowing from the motor terminal is connected between the drain terminal portions of the MOSFETs 400a and 400c and the pull-up resistor 402.

  The drain terminal partial voltage (VDa) of the MOSFETs 400a and 400c and the drain terminal partial voltage (VDb) of the MOSFETs 400b and 400d are input to the A / D converter 318a and converted into digital values. The digital value information is input to the CPU 308. The CPU 308 diagnoses the state of the motor terminal using the input value. Here, the connection destination of the pull-up resistor 402 in the motor voltage detection unit does not need to be VCC, and VB or another power source may be used.

  When the four MOSFETs (400a, 400b, 400c, 400d) are in the OFF state, VDa and VDb are an intermediate potential obtained by dividing the voltage obtained by subtracting the voltage applied to the diode from VCC by the pull-up resistor 402 and the pull-down resistor 404. However, if any one of the four MOSFETs (400a, 400b, 400c, 400d) is turned on, the voltage of VDa, VDb fluctuates, so that an abnormality can be detected. Become.

  The potential fixing unit 320 acts on each of the four MOSFETs (400a, 400b, 400c, 400d). For example, the MOSFET 400a includes an inverter 410a, a logical product 412a, a logical sum 414a, and a switch 416a. The inverter 410a receives the gate signal to the MOSFET 408b and outputs it to the logical product 412a. The logical product 412a receives the gate signal to the MOSFET 408a and the output of the inverter 410a and outputs them to the logical sum 414a. The logical sum 414a receives the output of the logical product 412a and the signal (416a_ON) from the CPU, and outputs them to the switch 416a. The switch 416a is disposed between the power supply 300 and the gate of the MOSFET 400a.

  For the MOSFET 400c, the potential fixing unit 320 includes, for example, an inverter 410b, a logical product 412b, a logical sum 414b, and a switch 416b. The inverter 410b receives the gate signal to the MOSFET 408d and outputs it to the logical product 412b. The logical product 412b receives the gate signal to the MOSFET 408c and the output of the inverter 410b, and outputs it to the logical sum 414b. The logical sum 414b receives the output of the logical product 412b and a signal (416b_ON) from the CPU, and outputs them to the switch 416b. The switch 416b is disposed between the GND and the gate of the MOSFET 400c.

  Note that the inputs of the switches (416a, 416b) are composed of an output of the logical product (412a, 412b) and a signal (416a_ON) from the CPU, which is a double system. Therefore, even if one of the two fails, the switch (416a, 416b) can be turned on by the other signal, so that an increase in dark current can be reliably prevented. Similarly, the switches (416a, 416b) can be reliably turned on even when the motor drive driver unit 312 breaks down. Here, the switches (416a, 416b) may be constituted by MOSFETs or the like. Although not shown directly in FIG. 4, the same circuit connection as described above is also configured for the MOSFETs (400b, 400d).

  Tables 1 to 3 and FIG. 5 show a truth table that can be taken by the MOSFETs (400a, 400c) used in the first embodiment and waveforms in each state. In Table 1, the CPU 308 determines the VDa voltage or the VDb voltage in the high impedance state. In this case, in a state where there is no failure, the four MOSFETs (400a, 400b, 400c, 400d) are turned off. Hereinafter, the VDa (VDb) voltage in a normal state without a failure and a failure state is shown. However, it is assumed that the pull-up resistor 402, the pull-down resistor 404 = 5.1 KΩ, and the power supply (VCC) = 5V.

In the normal state (the state of FIG. 5E),
VDa (VDb) = 5.1 KΩ / (5.1 KΩ + 5.1 KΩ) × 5 V
= 2.5V
Thus, an intermediate potential between Vref1 and Vref2 is obtained.

In the abnormal state (the state of FIG. 5 (F)),
VDa (VDb) = indefinite, exceeding Vref1 and less than Vref2, and VDa (VDb) is not stable and becomes indefinite. According to the above, VDa (VDb) takes an intermediate potential in the normal state, but failure detection is possible because the diagnosis lower limit threshold Vref1 and the diagnosis upper limit threshold Vref2 deviate in the abnormal state.

  FIG. 6 shows a flowchart of the fault diagnosis of this embodiment. When the battery and the power supply 300 supplied from the alternator driven by the engine are supplied to the motor control device 302 for the seat belt retractor, the vehicle battery voltage is supplied to the power supply circuit 306 inside the control device 302. The power supply circuit 306 generates a voltage VCC = 5 V to be supplied to a signal system element such as the CPU 308 that performs signal processing from the vehicle battery voltage, and starts operation (600). Next, the CPU 308 is reset (602). Thereafter, the CPU 308 sets the MOSFETs 400a to 400d to high impedance in order to start the initial diagnosis of the drain terminals VDa of the MOSFETs 400a and 400c and the drain terminal partial voltage VDb of the MOSFETs 400b and 400d (604). By performing diagnosis of the potential fixing unit 320 in the initial diagnosis (604), a failure can be detected at an appropriate timing.

  First, an initial diagnosis of VDa is performed (606). When the voltage of VDa is not an intermediate potential and is outside the diagnosis lower limit threshold Vref1 and the diagnosis upper limit threshold Vref2, the CPU 308 determines that the motor terminal is in a power supply fault state or a ground fault state, and determines the failure. At this time, the CPU 308 determines that a failure has occurred (608), and by setting 416a_ON to 416d_ON to HI, the switches (416a to 416d) are set to ON to prevent an increase in dark current. Thereafter, the high impedance setting of MOSFETs 400a to 400d is canceled, the initial diagnosis is finished (612), and then the control is finished (614).

  On the other hand, in the initial diagnosis of VDa, if the drain terminal VDa voltage of the MOSFET indicates a normal intermediate potential, then the initial diagnosis of VDb is performed (610). When the voltage of VDb is not the intermediate potential and is outside the diagnosis lower limit threshold Vref1 and the diagnosis upper limit threshold Vref2, the CPU 308 determines that the motor terminal is in a power supply fault state and a ground fault state, and determines the failure. At this time, the CPU 308 determines that a failure has occurred (608), and by setting 416a_ON to 416d_ON to HI, the switches (416a to 416d) are set to ON to prevent an increase in dark current. Thereafter, the high impedance setting of MOSFETs 400a to 400d is canceled, the initial diagnosis is finished (612), and then the control is finished (614).

  Further, in the initial diagnosis of VDb, when the drain terminal VDb voltage of the MOSFET indicates an intermediate potential of a normal value, the CPU 308 determines that it is normal, cancels the high impedance setting of the MOSFETs 400a to 400d, and finishes the initial diagnosis (612). The control is terminated (614). Here, if it is determined that there is a failure, motor driving is prohibited. When the failure is confirmed, the potential fixing unit 320 fixes the potential of the motor driving unit 310 to OFF, so that a low current consumption state is maintained and an increase in dark current is prevented. Moreover, it is good also as a system which lights a warning lamp simultaneously. Further, as an initial diagnosis, it is possible to perform control for diagnosing only one of the voltages of VDa and VDb, rather than diagnosing both.

[Example 2]
Next, another embodiment of the present invention will be described. In the second embodiment, an example of a motor control device for a seat belt retractor capable of performing failure diagnosis at a lower cost will be described.

  FIG. 7 is a control circuit diagram of the motor control device for the seat belt retractor in the second embodiment. In FIG. 7, the description of the components having the same functions as those shown in FIG. 4 already described in FIG. 4 is omitted. In the second embodiment, the pull-up resistor 700 and the pull-down resistor 702 are used for the potential fixing unit 320 that fixes the gate voltages of the four MOSFETs (400a, 400b, 400c, and 400d) constituting the H bridge.

  By providing a signal that turns off both the set of MOSFETs (408a, 408c) that provide VDa and the set of MOSFETs (408b, 408d) that provide VDb, the same high level as in the low current consumption state is provided. When the impedance state is established, the pull-up resistor 700 and the pull-down resistor 702 are provided so that the MOSFETs (400a and 400c) are fixed to a voltage that is turned off. The pull-up resistor 700 and the pull-down resistor 702 preferably have a resistance value of about 1 MΩ so as not to affect normal PWM control. In the second embodiment, since the potential fixing unit 320 is configured by only a resistor, the configuration of the motor control device can be simplified, and cost reduction can be achieved.

  Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the above-described embodiments, and various designs can be made without departing from the spirit of the present invention described in the claims. It can be changed. For example, the above-described embodiments have been described in detail for easy understanding of the present invention, and are not necessarily limited to those having all the configurations described. Further, a part of the configuration of one embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of one embodiment. Further, it is possible to add, delete, and replace other configurations for a part of the configuration of each embodiment.

  Further, the control lines and information lines indicate what is considered necessary for the explanation, and not all the control lines and information lines on the product are necessarily shown. Actually, it may be considered that almost all the components are connected to each other.

100: retractor 102: obstacle sensor 104: wheel speed sensor 106: collision determination controller 108: brake assist device 110: seat belt drive controller 112: vehicle 200: motor 202: occupant 204: seat 206: seat belt 300: power supply 302 : ECU (motor control device)
304: Custom IC
306: Power supply circuit 308: CPU (abnormality determination means)
310: Motor drive unit 312: Motor drive driver unit 314: Motor voltage detection unit 316: Current detection unit 318a, 318b: A / D converter 320: Potential fixing unit 400a to 400d: MOSFET
402: Pull-up resistor 404: Pull-down resistor 406: Diodes 408a to 408d: Driver MOSFET
410a, 401b: inverters 412a, 412b: logical products 414a, 414b: logical sums 416a, 416b: switch 700: potential fixing pull-up resistor 702: potential fixing pull-down resistor

Claims (6)

A motor drive unit for driving the motor;
A motor drive driver unit for generating a PWM signal for driving the motor drive unit;
A potential fixing unit that fixes the potential so as to turn off the motor driving unit at the time of low current consumption;
A motor voltage detector for detecting a voltage applied to the terminal of the motor;
An A / D converter for A / D converting the voltage signal detected by the motor voltage detector;
An abnormality determining means for determining whether or not the potential fixing unit is normal based on the voltage signal A / D converted by the A / D converter,
The motor control device according to claim 1, wherein when the abnormality determination unit determines that an abnormality has occurred, the potential fixing unit fixes the potential to the motor driving unit off.   2. The motor control device according to claim 1, wherein the motor drive driver unit sets a state of the motor drive unit to a high impedance state which is the same as that at the time of low current consumption.   The potential fixing unit uses a logical sum of a signal indicating a high impedance state from the motor driving driver unit and a signal from the control unit as an input signal, and fixes the potential to turn off the motor driving unit based on the input signal. The motor control device according to claim 1.   The abnormality determining means is a potential fixing unit that fixes the potential to turn off the motor driving unit based on a voltage signal when the motor driving unit is in a high impedance state that is the same as when the current consumption is low. The motor control device according to claim 1, wherein it is determined whether or not a failure has occurred.   The motor control device according to claim 1, wherein the potential fixing unit is a resistor connected to a potential at which the motor driving circuit is turned off.   6. A seat belt device using the motor control device according to claim 1 to wind up a seat belt with the motor.

Images