JP6090054B2 - Load drive device - Google Patents

Description

  The present invention relates to a load driving device that supplies power to a load such as a motor by driving a switching element.

  Conventionally, Patent Document 1 proposes a device that drives a motor by supplying power from a DC power source to a motor as a load based on on / off driving of a switching element. In this device, in order to improve the life of the motor, the duty is controlled so that the motor is started by supplying a voltage lower than a predetermined voltage at start-up, and gradually increased to a predetermined voltage after starting or within an arbitrary time. doing. As a result, the inrush current can be reduced, and the motor life can be improved.

Japanese Patent Laid-Open No. 9-317689

  However, as described above, if the voltage applied uniformly to the motor at startup is set to a voltage lower than a predetermined voltage, control according to the situation cannot be performed. For example, when starting a motor provided in a system that requires responsiveness, such as a brake device, if the voltage applied to the motor is uniformly lower than a predetermined voltage, the responsiveness is ensured. I can't. In particular, when the viscosity resistance of the brake fluid increases, such as at low temperatures, the responsiveness tends to deteriorate, making it difficult to ensure the responsiveness. For this reason, an apparatus as shown in Patent Document 1 cannot be applied to a system that requires responsiveness.

  In brake devices, in order to increase safety, demands for higher output and higher response are increasing. In order to obtain high output and high response, it is sufficient to increase the current supplied to the motor at the time of startup (hereinafter referred to as startup current). Become.

  In view of the above points, an object of the present invention is to provide a load driving device capable of achieving both high output and high response and load reduction of an in-vehicle power supply system.

  In order to achieve the above object, according to the first aspect of the present invention, current supply means for supplying a starting current by turning on the switching element at the start of driving the load (2), and supplying the starting current at the start of driving the load. Determining means for determining that the inrush current generated exceeds the current power supply capacity that is the upper limit of current that can be supplied as the supply current to the load, and when it is determined that the inrush current exceeds the current power supply capacity And a current regulating means for regulating the supply of the starting current to the load by controlling the on / off of the switching element (4) to regulate the inrush current to the current power source capacity.

In this way, it is determined whether or not the inrush current generated at the start of driving the load exceeds the power supply current capacity. When the inrush current exceeds the power supply current capacity, the switching element is driven on and off. Thereby, the supply current to the load can be regulated up to the power supply current capacity. In this way, it is possible to reduce the load on the in-vehicle power supply system by regulating the load current capacity when the load current exceeds the power supply current capacity at the time of the inrush current while increasing the load startup current to achieve high response. Therefore, it is possible to provide a load driving device capable of achieving both high output and high response and load reduction of the in-vehicle power supply system.
According to the first aspect of the present invention, the current supply means performs on / off control of the starting current supply to the load by performing on / off control of the switching element at the start of driving of the load, and the determination means is controlled to be on / off. It is determined whether or not the inrush current in the start-up current exceeds the current power supply capacity, and when the determination means determines that the inrush current does not exceed the current power supply capacity, the switching element is continuously turned on. Thus, the starting current is continuously supplied to the load.
As a result, it is possible to regulate the case where the power supply current capacity is exceeded at the time of inrush current while increasing the starting current to the load to achieve high response. Further, since the switching element is driven on and off immediately after the start of driving of the load, the increase of the inrush current is restricted. For this reason, it is possible to make the inrush current hardly exceed the power source current capacity.

  In addition, the code | symbol in the bracket | parenthesis of each said means shows an example of a corresponding relationship with the specific means as described in embodiment mentioned later.

1 is a diagram illustrating a schematic configuration of a motor drive device 1 according to a first embodiment of the present invention and a drive circuit of a motor 2 driven by the motor drive device 1; 3 is a time chart showing characteristics of a starting current described in the first embodiment. It is a time chart of the starting current at the time of applying the drive method of the motor 2 demonstrated in 1st Embodiment. It is a time chart of starting current at the time of applying the drive method of motor 2 explained in a 2nd embodiment.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following embodiments, parts that are the same or equivalent to each other will be described with the same reference numerals.

(First embodiment)
A load driving apparatus according to a first embodiment of the present invention will be described with reference to FIG. As shown in FIG. 1, in this embodiment, a motor drive device 1 is taken as an example of a load drive device, and when the motor 2 is driven by the motor drive device 1, high output and high response and a load of the in-vehicle power supply system are shown. A case where both reductions are achieved will be described.

  The motor drive device 1 is configured by a known microcomputer including a CPU, ROM, RAM, I / O, and the like, and controls power supply from the DC power supply 3 to the motor 2 according to a program stored in advance. The motor 2 is driven. Then, the motor drive device 1 grasps the power supply current capacity that is the upper limit value of the current that can be used for driving the motor 2 in consideration of the amount of power generated by the battery capacity, the alternator, and the like and the amount of current used in other in-vehicle electrical components The current supply to the motor 2 is controlled based on the power supply current capacity.

  The motor drive device 1 controls the current supply to the motor 2 by controlling the switching element 4 provided in the current supply path of the motor 2. In the case of this embodiment, the drive circuit of the motor 2 driven by the motor drive device 1 is a high-side drive drive circuit in which the switching element 4 is connected to the high side of the motor 2. For this reason, the current supply to the motor 2 is controlled by controlling the switching element 4 on the high side of the motor 2.

  Specifically, the motor drive device 1 controls on / off of the switching element 4 by outputting a command signal to the switching element 4 through the drive instruction terminal. The amount of current supplied to the motor 2 can be controlled by controlling on / off of the switching element 4 by duty control or PWM control. For example, as the switching element 4, an intelligent power device (hereinafter referred to as IPD) 4b including a MOS transistor 4a is used. The IPD 4b controls on / off of current supply to the motor 2 by controlling the gate voltage applied to the gate of the MOS transistor 4a to turn on / off the MOS transistor 4a.

  The motor driving device 1 monitors a current supplied to the motor 2 (hereinafter referred to as a supply current). For example, as shown in FIG. 1, the IPD 4b is provided with a current sensing function for monitoring current, and is input to the A / D input terminal of the motor drive device 1 through the output terminal CSNS. The resistor 5 connected to the wiring connecting the output terminal CSNS and the motor drive device 1 is a pull-down resistor 5.

  Further, as shown in FIG. 1, a shunt resistor 6 is connected in series to the motor 2, and a voltage between the motor 2 and the shunt resistor 6 (hereinafter referred to as an intermediate potential) is input to the motor driving device 1. May be. This intermediate potential is a voltage applied to the shunt resistor 6 and has a value corresponding to the current flowing through the shunt resistor 6, that is, the current supplied to the motor 2. Therefore, by monitoring the intermediate potential, the motor 2 The current supplied to can be monitored.

  The motor 2 is applied, for example, as a drive motor for an electric pump (not shown) for controlling brake fluid pressure. In this case, for example, when brake control such as anti-lock brake (hereinafter referred to as ABS) control, skid prevention control, traction control, pre-crash control, adaptive cruise control (hereinafter referred to as ACC) control is executed, the motor 2 Driven. For example, when the ABS control is executed, the brake fluid discharged from the wheel cylinder of the target wheel by the pump operation based on the drive of the motor 2 is returned to the master cylinder side. Also, when skidding prevention control, traction control, pre-crash control, ACC control, etc. are executed, the brake fluid is pumped from the master cylinder side by the pump operation based on the drive of the motor 2, and the wheel cylinder of the target wheel is added. Press. When performing such an operation, the motor 2 is driven.

  With such a configuration, the motor drive device 1 and the drive circuit of the motor 2 driven by the motor drive device 1 are configured. Next, a method for driving the motor 2 by the motor driving apparatus 1 according to the present embodiment will be described.

  First, the concept of the driving method of the motor 2 will be described with reference to FIG. As shown in FIG. 2, when a starting current is supplied to start driving the motor 2, an inrush current is generated, and then the current is lowered to a value determined by the resistance value of the motor 2 serving as a load and becomes a steady current. . At this time, since the copper wire constituting the winding of the motor 2 and the current supply path to the motor 2 has a temperature characteristic, an inrush current can be used for driving the motor 2 based on the temperature. May exceed power supply current capacity. In particular, at low temperatures, the inrush current tends to increase, and the value of the starting current tends to exceed the power supply current capacity. In such a case, it is necessary to regulate the supply current to the motor 2 in consideration of the battery capacity, the amount of power generated by the alternator, and the amount of current used in other in-vehicle electrical components. For this reason, in this embodiment, the supply current to the motor 2 is regulated by the following method.

  Specifically, first, in the motor drive device 1, the switching element 4 is turned on, and a starting current is supplied to the motor 2. At this time, the switching element 4 is fully turned on, that is, continuously turned on by setting the duty ratio to 100% or setting the pulse width in the PWM control to be always on. As a result, the starting current is continuously supplied to the motor 2.

  The supply of such a starting current generates an inrush current as shown in FIG. The current supplied to the motor 2 is monitored, and it is determined from the monitoring result whether the inrush current exceeds the power source current capacity. If the inrush current does not exceed the power supply current capacity, the current supply to the motor 2 is continued with the switching element 4 fully turned on. Further, when the inrush current exceeds the power supply current capacity, the switching element 4 is controlled to be turned on / off to restrict the increase in the supply current to the motor 2. For example, the duty ratio of the duty control is reduced, the pulse width at the time of turning on in the PWM control is set, the switching element 4 is switched to on / off driving, and the increase in the supply current to the motor 2 is regulated. Thus, as shown in FIG. 3, even if the supply current to the motor 2 when the switching element 4 is fully turned on exceeds the power supply current capacity (broken line in the figure), the switching element 4 is By performing on-off driving, the supply current is regulated up to the power supply current capacity (solid line in the figure).

  In this way, the motor drive device 1 is determined to determine whether or not the inrush current generated at the start of driving the motor 2 exceeds the power supply current capacity. When the inrush current exceeds the power supply current capacity, the switching element 4 is connected. Drive on and off. Thereby, the supply current to the motor 2 can be regulated up to the power supply current capacity.

  According to such a driving method, the start-up current of the motor 2 is increased to achieve a high response, and when the power supply current capacity is exceeded at the time of the inrush current, it is regulated to reduce the load on the in-vehicle power supply system. Is possible. Therefore, it becomes possible to make the motor drive device 1 a load drive device capable of achieving both high output and high response and load reduction of the in-vehicle power supply system. Further, it is not necessary to secure the power supply current capacity of the in-vehicle power supply system for the purpose of securing the starting current of the motor 2. Further, it is conceivable that the switching element 4 is overheated and damaged when the supply current to the motor 2 is large. However, according to this embodiment, the supply current to the motor 2 is not excessive. it can. For this reason, it is possible to monitor the change in the starting current due to the temperature state of the motor 2 at a low cost without adding a temperature sensor or the like.

(Second Embodiment)
A second embodiment of the present invention will be described. In this embodiment, the driving method of the motor 2 is changed with respect to the first embodiment, and other parts are the same as those in the first embodiment, and therefore only the parts different from the first embodiment will be described. To do.

  In the first embodiment, when the driving of the motor 2 is started, the starting current is supplied to the motor 2 with the switching element 4 fully turned on, that is, continuously turned on. On the other hand, in this embodiment, as shown in FIG. 4, at the start of driving of the motor 2, the motor 2 is turned on / off by setting the switching element 4 to a predetermined duty ratio smaller than 100% or a predetermined pulse width. Supply the start-up current. Then, it is determined whether or not the inrush current generated at the start of driving of the motor 2 in the motor drive device 1 exceeds the power supply current capacity. If not, the duty ratio is set to 100% or the pulse width in PWM control. By setting the width to be always on, the switching element 4 is fully turned on. For example, since the period during which the inrush current is generated can be confirmed in advance, if the inrush current is smaller than the power supply current capacity before or after the elapse of the period, the switching element 4 may be switched to full on.

  In this way, the start-up current is restricted immediately after the start of driving of the motor 2, but if the inrush current does not exceed the power supply current capacity, the switching element 4 is fully turned on and a larger start-up is performed. Current is supplied to the motor 2. For this reason, it is possible to increase the starting current of the motor 2 to achieve a high response, and to control the load when the power supply current capacity is exceeded at the time of the inrush current to reduce the load on the in-vehicle power supply system. The same effect as the embodiment can be obtained. Further, since the switching element 4 is driven on and off immediately after the start of driving of the motor 2, an increase in inrush current is restricted. For this reason, it is possible to make the inrush current hardly exceed the power source current capacity.

  Also in the case of the present embodiment, when the inrush current exceeds the power supply current capacity after switching the switching element 4 to full on, the duty ratio of the switching element 4 is reduced as in the first embodiment. The pulse width is set, the switching element 4 is switched to on / off driving, and the increase in the supply current to the motor 2 is restricted. Thereby, the same effect as that of the first embodiment can be obtained.

(Other embodiments)
The present invention is not limited to the embodiment described above, and can be appropriately changed within the scope described in the claims.

  For example, in each of the above embodiments, the motor 2 is taken as an example of the load, and the motor driving device 1 that drives the motor 2 is taken as an example of the load driving device. However, the load that drives a load other than the motor 2 is explained. The present invention can also be applied to a driving device. Although the MOS transistor 4a has been described as an example of the switching element 4, the present invention is not limited to the MOS transistor 4b, and other elements (for example, an IGBT or a relay) can be used.

  In each of the above embodiments, each functional unit provided in the motor drive device 1 constitutes various means in the present invention. Specifically, in the motor drive device 1, the portion that supplies the starting current to the motor 2 is the current supply means, the portion that determines that the inrush current has exceeded the current power supply capacity is the determination means, and the motor 2 The part which controls the on-off control of the supply of the starting current to restrict the inrush current to the current power source capacity corresponds to the current regulating means.

  DESCRIPTION OF SYMBOLS 1 ... Motor drive device, 2 ... Motor, 3 ... DC power supply, 4 ... Switching element, 4a ... MOS transistor, 4b ... IPD, 5 ... Pull-down resistance, 6 ... Shunt resistance

Claims (1)

Applied to a drive circuit for the load, comprising: a DC power supply (3) for supplying power to the load (2); and a switching element (4) for turning on and off current supply from the DC power supply to the load. In a load driving device that controls current supply to the load by controlling on / off,
Current supply means for supplying a starting current by turning on the switching element at the start of driving the load;
A determination means for determining that an inrush current generated when a starting current is supplied at the start of driving of the load exceeds a current power supply capacity that is a current upper limit value that can be supplied as a supply current to the load;
When it is determined that the inrush current has exceeded the current power supply capacity, the switching element is turned on / off to turn on / off the supply of the starting current to the load, and the inrush current is converted into the current power supply capacity. A current regulating means for regulating ,
The current supply means performs on / off control of the supply of the starting current to the load by performing on / off control of the switching element at the start of driving of the load,
The determination means determines whether or not the inrush current in the start-up current that is on-off controlled exceeds the current power supply capacity,
Further, when the determination means determines that the inrush current does not exceed the current power supply capacity, the switching element is continuously turned on to continuously supply the starting current to the load. A load driving device.

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