JP2017183108A - Vehicle bulb drive device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vehicle bulb drive device in which both lighting performance and durability are achieved.SOLUTION: This vehicle bulb drive device comprises: a switching element that has particularly an electric-field relaxation structure and controls current flowing in a bulb; a control part that controls turning on/off of the switching element; and a current detection part that detects a current output from the switching element. The control part has an automatic re-start function that turns off the switching element when the output current is equal to or higher than a predetermined threshold current, and automatically turns on the switching element after an elapse of the predetermined time. Additionally, as an operation mode for the switching element, the bulb drive device has a lighting-on priority mode in which lighting on of the bulb is given priority, and a protection priority mode in which protection of the switching element is given priority. If an instruction to light on the bulb is given, the switching element is driven in the lighting-on priority mode. Thereafter, shift to the protection priority mode takes place. A time period required to reach the automatic re-start in the lighting-on priority mode is set shorter than the time interval in the protection priority mode.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a vehicle valve drive device that has an auto-restart function and drives a valve (light) mounted on a vehicle.

  Energization of bulbs used in lighting devices such as headlamps and backlamps in vehicles is controlled by a semiconductor switching element. In recent years, there has been a demand for power saving and downsizing for valve driving devices that drive valves, and switching elements for driving control are also required to have low on-resistance and miniaturization. In response to this demand, a switching element having an electric field relaxation structure such as a partial thickening of an insulating film in a super junction, a field plate, or a trench gate has been proposed.

  On the other hand, the amount of heat generated per unit area increases with the miniaturization of switching elements that employ an electric field relaxation structure, and reliability against heat generation is required. In particular, a halogen bulb used in a vehicle generates a higher inrush current than that generally used at home. For this reason, for example, heat loss at the time of overcurrent detection is large, and a small switching element particularly requires reliability against heat generation. The battery pack described in Patent Document 1 includes current detection means and switch means for cutting off power supply from the battery when a current (overcurrent) of a predetermined value or more flows. The switch means has a so-called auto-restart function that is controlled so as to be automatically energized after a predetermined time after detecting the overcurrent. That is, by repeating the stop of energization by the switch means and the automatic restart, it is possible to suppress heat generation due to energization without completely stopping energization.

JP 2007-28858 A

  By the way, in Patent Document 1, it is only necessary to determine a predetermined time until auto-restart is executed for the purpose of ensuring durability in order to suppress overheating of the battery pack due to overcurrent and to protect the switch means. The auto restart function operates at a relatively long time interval (several hundred msec to several sec order). If this is applied to driving a vehicle valve, the time interval until auto-restart is long, so the valve filament is not sufficiently warmed up, and there is a possibility that early lighting characteristics cannot be secured. That is, the durability of the switch means or the battery pack can be ensured, but the lighting performance cannot be ensured.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a vehicle valve drive device that achieves both lighting performance and durability.

  The invention disclosed herein employs the following technical means to achieve the above object. Note that the reference numerals in parentheses described in the claims and in this section indicate a corresponding relationship with specific means described in the embodiments described later as one aspect, and limit the technical scope of the invention. Not what you want.

  In order to achieve the above object, the present invention provides a vehicle valve drive device for driving a valve for a vehicle, which has an electric field relaxation structure, controls a current flowing through the valve, and on / off of the switching element. A control unit for controlling the output current, and a current detection unit for detecting the output current of the switching element. The control unit turns off the switching element when the output current is equal to or higher than a predetermined threshold current, and automatically In addition to the auto-restart function that turns on, the operation mode of the switching element has a lighting priority mode that prioritizes lighting of the bulb and a protection priority mode that prioritizes protection of the switching element. When this is done, the switching element is driven in the lighting priority mode, and then the protection priority mode is entered. Time interval reaching the auto-restart in de is set shorter than the time interval in the protection priority mode.

  According to this, immediately after the bulb is instructed to turn on, the valve is energized in the lighting priority mode in which the auto-restart interval is shorter than the protection priority mode as the operation mode. Even when an overcurrent is detected by a state, for example, an inrush current of the bulb, the possibility of lighting can be increased while warming up the bulb. In addition, in the protection priority mode, since the auto-restart interval is longer than in the lighting priority mode, overheating of the switching element can be suppressed.

It is a block diagram showing a schematic structure of a valve drive device for vehicles concerning a 1st embodiment. It is a timing chart which shows operation | movement of the valve drive apparatus for vehicles. It is a block diagram which shows schematic structure of the valve drive apparatus for vehicles which concerns on 2nd Embodiment. It is a timing chart which shows operation | movement of the valve drive apparatus for vehicles. 10 is a timing chart showing the operation of the vehicle valve drive device according to Modification 2.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following drawings, the same reference numerals are given to the same or equivalent parts. In the case where only a part of the configuration is described in each embodiment, the other parts of the configuration are the same as those described previously. In addition to the combination of parts specifically described in each embodiment, the embodiments may be partially combined as long as the combination is not particularly troublesome.

(First embodiment)
Initially, with reference to FIG. 1, schematic structure of the valve drive apparatus for vehicles which concerns on this embodiment is demonstrated.

  The vehicle valve drive device 100 according to the present embodiment controls lighting of the halogen bulb mounted on the vehicle to turn on, turn off, and light control the halogen bulb. The halogen bulb is used in, for example, a head lamp, a back lamp, other brake lamps, flashers, and the like. The halogen bulb emits light when the filament is energized.

  As shown in FIG. 1, the vehicle valve drive device 100 includes a switching element 10, a control unit 20, a current detection unit 30, a timer 40, and a counter 50.

  As the switching element 10, generally known MOSFETs or IGBTs can be adopted, but the switching element 10 in the present embodiment will be described by taking a MOSFET with an electric field relaxation structure as an example. The MOSFET in which the electric field relaxation structure is formed is, for example, a MOSFET having a so-called super junction (SJ) structure having a pn column structure in which P conductivity type regions and N conductivity type regions are alternately formed in the drift layer. It is. In the SJ structure, since the depletion layer extends in a direction perpendicular to the extending direction of the column, a uniform depletion layer can be formed in the depth direction to ensure a breakdown voltage. Therefore, the impurity concentration of the drift layer can be relatively increased to achieve a low on-resistance. Similarly, by forming a field plate to make the electric field in the drift layer uniform, ensuring a withstand voltage, while achieving a relatively high on-resistance by increasing the impurity concentration of the drift layer, or a trench gate In some cases, a low on-resistance is realized by thickening a part of the insulating film and relaxing the electric field between the trench gates. Hereinafter, MOSFETs including these structures are collectively referred to as MOSFETs having an electric field relaxation structure. For example, the electric field relaxation structure in the case of IGBT includes a structure that secures a withstand voltage by forming a field plate, and a structure that relaxes the electric field between the trench gates by thickening a part of the insulating film of the trench gate. .

  The switching element 10 is connected in series with a valve 200 serving as a load with respect to the power supply VCC. When a predetermined gate voltage is applied to the gate terminal of the switching element 10 by the control unit 20 described later, the switching element 10 is turned on and a current flows through the valve 200. This energizes the filament and turns on the bulb 200.

  As shown in FIG. 1, in the present embodiment, a current detection element 11 is formed in parallel with the switching element 10. The current detection element 11 is, for example, a MOSFET, and a sense current corresponding to the output current flowing between the drain and source of the switching element 10 can be taken out. The current detection element 11 is formed on the same semiconductor substrate as the switching element 10, and the same gate voltage as that of the switching element 10 is supplied from the control unit 20.

  The source terminal of the current detection element 11 is connected to the source terminal of the switching element 10 via the shunt resistor 12. A current detection unit 30 described later can detect the current value of the sense current and consequently the current value of the output current of the switching element 10 based on the potential difference between both ends of the shunt resistor 12 and the known shunt resistance value. The current detector 30 is configured to detect an overcurrent by comparing the detected sense current with a predetermined threshold.

  The control unit 20 controls on / off of the switching element 10. The control unit 20 turns on the switching element 10 by applying a gate voltage to the gate terminal of the switching element 10. In the present embodiment, the switching element 10 being turned on includes a case where a pulse signal subjected to PWM control is input as a gate voltage. The dimming of the valve can be performed by adjusting the duty ratio related to the PWM control.

  The control unit 20 in this embodiment has an auto restart function. As described later, when an overcurrent state in which an output current equal to or higher than a predetermined threshold current flows in the switching element 10, the control unit 20 acts to turn off the switching element 10. However, after the switching element 10 is turned off, the output of the gate voltage is restarted so that the switching element 10 is automatically turned on after a predetermined time has elapsed. The operation of automatically turning on the switching element 10 and re-energizing the valve 200 is referred to as auto restart, and the function is referred to as auto restart function. That is, the predetermined time corresponds to a time interval from when the switching element 10 is turned off until auto restart is performed.

  And the control part 20 in this embodiment has a lighting priority mode and a protection priority mode as an operation mode of the switching element 10. The lighting priority mode is an operation mode in which the time interval to auto restart is set to be relatively short. On the other hand, the protection priority mode is an operation mode in which the time interval until auto restart is set longer than the lighting priority mode. In the present embodiment, as an example, the time interval in the lighting priority mode is set to 5 ms, for example, and the time interval in the protection priority mode is set to 20 ms, for example.

  When a command for lighting the bulb 200 is input to the control unit 20, the control unit 20 outputs a gate voltage to the switching element 10, but the switching element 10 immediately after the lighting command is driven in the lighting priority mode. . That is, if it is a situation where auto restart is necessary, the time interval until auto restart is 5 ms. If the valve 200 is normally lit in the lighting priority mode, the control unit 20 continues to turn on the bulb 200 by keeping the switching element 10 on. On the other hand, when the condition requiring auto restart continues and satisfies a predetermined condition, the control unit 20 shifts the operation mode of the switching element 10 from the lighting priority mode to the protection priority mode.

  As described above, the current detection unit 30 detects the current value of the output current flowing through the switching element 10 based on the sense current. The current detection unit 30 holds a predetermined threshold current therein. When the detected output current of the switching element 10 is equal to or greater than the threshold current, the control unit 20 is instructed to turn off the switching element 10. The control unit 20 turns off the switching element 10 based on this instruction.

  The timer 40 is connected to the control unit 20 and measures the time from when the energization of the switching element 10 is stopped due to an overcurrent state until the next auto-restart. The control unit 20 restarts the supply of the gate voltage to the switching element 10 when the time measured by the timer 40 reaches a predetermined time after turning off the switching element 10 by detecting the overcurrent. That is, auto restart is executed. As described above, when the operation mode is the lighting priority mode, the control unit 20 executes auto-restart on the condition that the timer 40 has counted 5 ms. Similarly, when the operation mode is the protection priority mode, the control unit 20 executes auto-restart on the condition that the timer 40 has counted 20 ms.

  The counter 50 is connected to the control unit 20 and counts the number of times that auto-restart is executed. In particular, the counter 50 counts the number of auto-restarts in the lighting priority mode, and outputs the count number to the control unit 20. When the number of auto restarts reaches a predetermined threshold number, the control unit 20 shifts the operation mode of the switching element 10 from the lighting priority mode to the protection priority mode. That is, the predetermined condition for the control unit 20 to shift the operation mode of the switching element 10 from the lighting priority mode to the protection priority mode described above is that the number of auto-restarts counted by the counter 50 reaches a predetermined threshold number. . Although the predetermined threshold number of times can be set arbitrarily, it can be set to 20 times, for example.

  In the present embodiment, as an example, the time interval in the lighting priority mode is set to 5 ms, for example, and the time interval in the protection priority mode is set to 20 ms, for example, but this is not restrictive. Since the heat generated by the overcurrent of the bulb 200 in the vehicle is larger than that of a household bulb, if the time interval of auto restart in the lighting priority mode is too short, an overheat state may occur. Therefore, the time intervals in the lighting priority mode and the protection priority mode should be set as appropriate. For example, the auto-restart time interval in the lighting priority mode is appropriately set in the range of 2.5 ms to 10 ms, and the time interval in the protection priority mode is appropriately set in the range of 10 ms to 30 ms.

  Initially, with reference to FIG. 2, operation | movement and effect of the valve drive apparatus for vehicles which concern on this embodiment are demonstrated.

  Assume that there is an instruction to turn on the bulb 200 at time t1 shown in FIG. When the switching element 10 is turned on, an output current flows and the element temperature rises due to power consumption. At this time, the temperature of the valve 200 itself also rises.

  The output current that flows at the time t1 is an inrush current, which may exceed the threshold current defined by the current detection unit 30. When the output current becomes equal to or greater than the threshold current defined by the current detection unit 30 at time t2, the control unit 20 turns off the switching element 10.

  The controller 20 initially operates in the lighting priority mode. Therefore, when the control unit 20 detects that 5 ms has elapsed from time t2 by the timer 40 after the switching element 10 is turned off, the control unit 20 turns on the switching element 10 again. That is, auto restart is executed at time t3 shown in FIG. This is the first auto restart, and the counter 50 increments the count as the number of auto restarts. Thereafter, when the output current reaches the threshold current again, the switching element 10 is turned off, and the timer 40 starts measurement. Then, auto restart is executed at time t4 after 5 ms. This is the second auto restart, and the counter 50 increments the auto restart count.

  When the 20th auto-restart is executed at time t5, the control unit 20 shifts the operation mode from the lighting priority mode to the protection priority mode. After the automatic restart at time t5, when the output current reaches the threshold current, the control unit 20 turns off the switching element 10 as in the lighting priority mode. When the timer 40 detects that 20 ms has elapsed after the switching element 10 is turned off, the control unit 20 turns on the switching element 10 again. That is, auto restart is executed at time t6 shown in FIG. Thereafter, auto restart is executed at a time interval of 20 ms.

  After the lighting instruction is given, the output current flows through the filament of the bulb 200 in a relatively short period during the period of operation in the lighting priority mode. For this reason, since electricity supply is performed again before the filament temperature falls to the environmental temperature, the valve 200 can be warmed up efficiently. That is, lighting performance can be improved. If the inrush current is reduced to a level that does not reach the threshold current by increasing the resistance of the filament by heating, continuous lighting of the bulb 200 can be realized.

  On the other hand, as shown in FIG. 2, not only the filament temperature but also the element temperature of the switching element 10 may increase during the lighting priority mode. Therefore, the vehicle valve drive device 100 according to the present embodiment shifts to the protection priority mode on condition that 20 automatic restarts have been executed in the lighting priority mode. In the protection priority mode, the time interval until auto restart is set longer than that in the lighting priority mode. Therefore, it is possible to secure time for heat dissipation of the switching element 10. Therefore, overheating of the switching element 10 can be suppressed. That is, durability can be improved.

  Further, in any operation mode of the lighting priority mode and the protection priority mode, the valve 200 is energized by the auto restart, so that there is a possibility that the valve 200 is warmed up and lit. . Thereby, for example, when the user transports the vehicle for repair, the vehicle can be moved with the bulb 200 turned on.

(Modification 1)
In the transition from the lighting priority mode to the protection priority mode, in the first embodiment described above, the threshold number for the number of times of auto-restart is set to 20, but the threshold number may be variable. In particular, the number of thresholds is preferably variable depending on the type of valve 200 connected to the switching element 10.

  If the valve 200 is of a type that is difficult to warm against energization of the filament, the threshold number may be set to be greater than 20, and conversely, if it is of a type that is likely to be warmed, the threshold number of times is set to be less than 20. May be.

  If the valve 200 to be connected is determined and fixed according to the specification, the threshold number may be set in advance for each type. On the other hand, if the specification allows the user to replace the valve 200 with a certain degree of freedom, for example, a threshold count corresponding to the valve 200 may be set. Alternatively, the resistance value of the filament of the connected valve 200 may be detected to automatically set the corresponding threshold number.

(Second Embodiment)
In addition to the vehicle valve drive device 100 in the first embodiment, the vehicle valve drive device 110 in the present embodiment detects the element temperature of the switching device 10 in the vicinity of the switching device 10 as shown in FIG. An element temperature detection unit 60 is further provided.

  The element temperature detection unit 60 can employ a temperature sensitive diode using a PN junction diode, for example, and is connected to the control unit 20. The control unit 20 controls the switching element 10 based on the detected element temperature. For example, the time interval until auto restart in the lighting priority mode is controlled to be longer as the temperature of the switching element is higher.

  This will be specifically described below. As shown in FIG. 4, in the lighting priority mode, it is assumed that the temperature of the switching element 10 becomes equal to or higher than the threshold temperature at time t21. On the condition that the temperature of the switching element 10 maintains a threshold value or more during a predetermined filter time, the control unit 20 lengthens the time interval to reach auto restart. In the example of this embodiment, the time interval that was 5 ms is changed to 7 ms at time t22. Thereby, since the frequency of auto-restart can be reduced, an excessive increase in element temperature can be suppressed. It is preferable that the extended time interval in the lighting priority mode is set to be shorter than the time interval in the protection priority mode, so that the valve 200 is controlled to be warmed up as much as possible.

(Modification 2)
In the second embodiment described above, the example in which the time interval until the auto restart is extended is described on the condition that the switching element 10 maintains the element temperature equal to or higher than the threshold temperature for a predetermined filter time. On the other hand, in the present modification, an example will be described in which the time interval is not changed, and the value of the threshold current that is a condition for turning off the switching element 10 is lowered.

  As shown in FIG. 5, in the lighting priority mode, it is assumed that the temperature of the switching element 10 becomes equal to or higher than the threshold temperature at time t31. The controller 20 reduces the current value of the threshold current, which is a condition for turning off the switching element 10, on condition that the temperature of the switching element 10 is maintained at the threshold value or more during a predetermined filter time. In this modification, the threshold current is reduced in the operation period in the lighting priority mode after time t32. Thereby, since the energization current value in one auto restart can be reduced, an excessive increase in the element temperature can be suppressed.

(Other embodiments)
The preferred embodiments of the present invention have been described above. However, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention.

  In each of the above-described embodiments, the MOSFET in which the electric field relaxation structure is adopted as the switching element 10 has been described as an example. However, an IGBT similarly adopting the electric field relaxation structure may be used. In this case, the current detector unit 30 detects the output current at the sense emitter terminal provided in the current detection element 11.

  In the above-described embodiment, the example in which the time intervals of auto-restart in the lighting priority mode and the protection priority mode are set to 5 ms and 20 ms, respectively, is described, but the present invention is not limited to this example. It is only necessary that the time interval in the lighting priority mode is set shorter than that in the protection priority mode. Preferably, the time interval in the lighting priority mode should be set to maintain a temperature higher than the temperature before the instruction to turn on the bulb 200.

  In the above-described embodiment, an example has been shown in which the number of auto-restarts reaches 20 times as a condition for shifting from the lighting priority mode to the protection priority mode. It is not limited. The number of auto-restarts may be set to a value other than 20, or may be variable as described in the first modification.

DESCRIPTION OF SYMBOLS 10 ... Switching element, 11 ... Current detection element, 12 ... Shunt resistance, 20 ... Control part, 30 ... Current detection part, 40 ... Timer, 50 ... Counter, 100 ... Vehicle valve drive device, 200 ... Valve

Claims (8)

A vehicle valve drive device for driving a vehicle valve (200), comprising:
A switching element (10) having an electric field relaxation structure and controlling a current flowing through the bulb;
A control unit (20) for controlling on / off of the switching element;
A current detector (30) for detecting an output current of the switching element,
The control unit has an auto-restart function that turns off the switching element when the output current is equal to or greater than a predetermined threshold current, and automatically turns on after a predetermined time has elapsed.
The operation mode of the switching element includes a lighting priority mode that prioritizes lighting of the bulb and a protection priority mode that prioritizes protection of the switching element, and the lighting priority mode when the lighting of the bulb is instructed Driving the switching element at, and then the transition to the protection priority mode,
The vehicle valve drive device in which the time interval to the auto restart in the lighting priority mode is set shorter than the time interval in the protection priority mode.   2. The vehicle interval according to claim 1, wherein the time interval until the auto-restart in the lighting priority mode is set such that the temperature of the bulb is maintained higher than a temperature before an instruction to turn on the bulb. Valve drive device. An element temperature detector (60) for detecting the temperature of the switching element;
3. The vehicle valve drive device according to claim 1, wherein a time interval until the auto restart in the lighting priority mode is set longer as a temperature of the switching element is higher. An element temperature detector for detecting the temperature of the switching element;
4. The vehicle valve drive device according to claim 1, wherein in the lighting priority mode, the threshold current at which the switching element is turned off is set to be smaller as the temperature of the switching element is higher. A counter (50) for counting the number of times of the auto restart in the lighting priority mode;
The said control part transfers the operation mode of the said switching element to the said protection priority mode, if the frequency | count of the said auto restart in the said lighting priority mode reaches the predetermined threshold frequency | count. Vehicle valve drive device.   The vehicular valve drive device according to claim 5, wherein the threshold number of times is variable depending on a type of the valve.   The time interval to reach the auto restart in the lighting priority mode is set to 2.5 ms to 10 ms, and the time interval to the auto restart in the protection priority mode is set to 10 ms to 30 ms. The valve drive device for vehicles given in any 1 paragraph.   The vehicle according to any one of claims 1 to 7, wherein a time interval to reach the auto restart in the lighting priority mode is set to 5 ms, and a time interval to the auto restart in the protection priority mode is set to 20 ms. Valve drive device.

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