Vehicle Electronic Control Unit

Abstract

To provide an electronic control device for vehicles capable of preventing element destruction by preventing overcurrent from continuously flowing.SOLUTION: An electronic control device 10 comprises a power supply IC 2 by which, when a VB voltage is supplied from an on-vehicle battery 10 via a main relay MR of a vehicle, the VB voltage is regulated into a predetermined voltage and supplied to a mounted load. The power supply IC 2 includes: an overcurrent detection circuit 3 for detecting that overcurrent has occurred in a supply line 13 to which the VB voltage is supplied via a wiring resistor; a reset circuit 8 which resets the power supply IC 2 per se when the VB voltage becomes lower than a predetermined reset threshold; and an overcurrent detection counter 4 for measuring the number of times of detecting an overcurrent state by the overcurrent detection circuit 3. The overcurrent detection counter 4 is configured to be directly supplied with an operation voltage from the on-vehicle battery 10 without interposing the main relay MR and holds the number of times of the measurements regardless of a reset state of the power supply IC 2.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an electronic control device for a vehicle. [Background technology]

[0002] A power supply circuit called an overcurrent detection counter power supply is used as the power supply IC that supplies the VB voltage to the VB line. This power supply circuit has a built-in overcurrent detection counter, and when the number of measurements by the overcurrent detection counter to detect an overcurrent reaches a threshold, it prohibits power startup until the next time the startup switch is turned on. When an overcurrent flows due to an overload while the vehicle is running, a voltage drop occurs in the VB voltage for the vehicle. When an overcurrent flows, the overcurrent detection counter counts as mentioned above, but if the voltage on the VB line falls below a specified reset threshold, the power supply circuit itself is reset.

[0003] When the power supply circuit is reset, it stops supplying current to the load, so the voltage drop on the VB line is also alleviated, and then the power supply circuit starts supplying power. However, if an overcurrent continues to flow again on the VB line even after the power supply circuit starts supplying power, the power supply circuit will be reset again. When the power supply circuit is reset, the measurement value of the overcurrent detection counter returns to its initial value, and if an overcurrent continues to flow through the power supply circuit due to repeated power supply and reset operations, this is undesirable as it may damage the elements. Note that the technology described in Patent Document 1 is provided as a technology related to this application. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2015-192522 A Summary of the Invention [Problem to be solved by the invention]

[0005] An object of the present disclosure is to provide an electronic control device for a vehicle that can prevent element destruction by preventing a continuous flow of an overcurrent. [Means for solving the problem]

[0006] According to the invention described in claim 1, a power supply circuit is provided which, when an operating voltage is supplied from an on-board battery via a start switch of a vehicle, adjusts the operating voltage to a predetermined voltage and supplies the voltage to a load mounted on an electronic control device. The power supply circuit includes an overcurrent detection circuit which detects whether an overcurrent has occurred in a supply line which supplies the operating voltage, a reset circuit which resets the power supply circuit itself when the operating voltage falls below a predetermined reset threshold, and an overcurrent detection counter which measures the number of times an overcurrent state is detected by the overcurrent detection circuit. The overcurrent detection counter is configured so that the operating voltage is supplied directly from the on-board battery without passing through the start switch, and is configured to hold the measured number of times regardless of the reset state of the power supply circuit.

[0007] For example, when an overcurrent occurs in a supply line, the operating voltage supplied to the supply line drops significantly due to a voltage drop caused by wiring resistance. The reset circuit resets the power supply circuit itself when the operating voltage drops below a predetermined reset threshold. The power supply circuit stops supplying a predetermined voltage to the load by resetting. When the overcurrent state is resolved and the overcurrent no longer flows, the operating voltage rises. When the operating voltage rises, the power supply circuit returns from the reset state and restarts. If an overcurrent continues to flow in the supply line after this, the operating voltage drops significantly due to a voltage drop caused by wiring resistance, and the power supply circuit is reset again. In this way, the power supply circuit repeatedly resets and restarts. In this case, even if the power supply circuit is reset and restarted repeatedly, the overcurrent detection counter is configured to receive operating voltage directly from the vehicle battery without going through a start switch and holds the number of times it has detected an overcurrent state, so it can continuously count the number of times it has detected an overcurrent state. Therefore, for example, when the number of times it has detected an overcurrent state reaches a predetermined permanent overcurrent threshold, it is possible to stop the voltage adjustment operation of the power supply circuit so as not to allow the overcurrent to continue to flow. This prevents element destruction. [Brief description of the drawings]

[0008] [Figure 1] Electrical configuration diagram of a vehicle electronic control device according to an embodiment [Diagram 2] Time chart when the start-up switch is turned off and then turned on again to return to normal [Diagram 3] Time chart when abnormality continues after start operation switch is turned off and on [Figure 4] Time chart for when a momentary overcurrent fault occurs [Diagram 5] Time chart showing a comparative example DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] An embodiment of a vehicle electronic control device 1 will be described below with reference to the drawings. The vehicle electronic control device 1 is an ECU mounted on a vehicle, and is supplied with an operating voltage from an in-vehicle battery 10 through a main relay MR serving as a start switch for the vehicle. Hereinafter, the vehicle electronic control device 1 will be abbreviated as electronic control device 1. The main relay MR is turned on and off based on the start operation on and off of an ignition switch 11 serving as a start operation switch, and thus a VB voltage is supplied as an operating voltage from the in-vehicle battery 10 to the electronic control device 1 in response to a user operation of the ignition switch 11. This input VB voltage is input to a power supply IC2 serving as a power supply circuit.

[0010] When the power supply IC 2 receives the VB voltage from the vehicle battery 10 via the vehicle's main relay MR, the power supply IC 2 adjusts the VB voltage to a predetermined voltage and supplies it to a load mounted on the electronic control device 1, such as a control circuit 20.

[0011] A noise filter consisting of capacitors C1 and C2 and an inductor L1 arranged in a π configuration is configured on the VB voltage supply line 13. A current detection resistor R is configured on the VB voltage supply line 13, and the voltage between the terminals of the current detection resistor R is input to the overcurrent detection circuit 3 of the power supply IC2.

[0012] In addition, since the VB voltage supply line 13 is connected by extending a cable from the vehicle battery 10, there is a wiring resistance Rvb between the main relay MR and the VB terminal T1 of the electronic control device 1, and there is also a wiring resistance Rvb2 between the VB terminal T1 and the noise filter. In general, a large operating current of the electronic control device 1 flows through the supply line 13, so a large voltage drop occurs across the wiring resistances Rvb and Rvb2.

[0013] The VB voltage is also applied to switching elements M1 and M2 through a supply line 13. Each of the switching elements M1 and M2 is configured with a MOSFET, and the drain-source of the MOSFET is connected in series between the VB terminal T1 and ground.

[0014] An inductor Lo and a capacitor Co are connected in series between the common connection point of the switching elements M1, M2 and ground, and the common connection point of the inductor Lo and the capacitor Co is connected to a power supply terminal T3 to a load. The power supply terminal T3 is connected to a control circuit 20. The power supply unit 12 is configured by combining a power supply IC2, switching elements M1, M2, an inductor Lo and a capacitor Co, and supplies power to the control circuit 20, which serves as a load, via the power supply terminal T3.

[0015] The power supply IC 2 includes an overcurrent detection circuit 3 as an overcurrent detection unit, an overcurrent detection counter 4, a startup switch detection circuit 5 as a startup detection unit, pre-drivers 6 and 7 which drive the switching elements M1 and M2, respectively, and a power supply IC reset circuit 8. The overcurrent detection circuit 3 receives a VB voltage and detects whether or not an overcurrent has occurred in a supply line 13 to which the VB voltage is supplied.

[0016] When an overcurrent occurs in the supply line 13, the VB voltage supplied to the supply line 13 drops significantly due to a voltage drop caused by the wiring resistances Rvb and Rvb2. The power supply IC reset circuit 8 is configured to reset the power supply IC2 itself when the VB voltage drops below a predetermined reset threshold. When the overcurrent state is resolved and the overcurrent no longer flows, the VB voltage rises. The power supply IC2 is configured to return from the reset state and restart when the VB voltage rises. The start-up switch detection circuit 5 is configured to detect the state of an ignition switch 11 that starts the vehicle, and detects whether the start-up operation is turned on or off by a user. The ignition switch 11 is configured to be equivalent to a start-up switch.

[0017] The overcurrent detection counter 4 counts the number of times an overcurrent state is detected by the overcurrent detection circuit 3. The overcurrent detection counter 4 is configured to receive operating voltage directly from the vehicle battery 10 without going through the main relay MR. Therefore, the BATT voltage is constantly supplied to the overcurrent detection counter 4 through the BATT terminal T2, and the counted number can be held regardless of the reset state of the power supply IC2. The BATT voltage is supplied to the overcurrent detection counter 4 through the cable and the BATT terminal T2, but the power consumed at this time is not as much as the power based on the VB voltage, so there is little effect of voltage drop due to the internal resistance Rba of the cable connecting the BATT voltage.

[0018] The pre-drivers 6 and 7 can switch the driving operation between complementarily driving the switching elements M1 and M2 on and off based on the count value of the overcurrent detection counter 4, or stopping the power supply by driving the switching elements M1 and M2 off.

[0019] The effects of the above configuration will now be described. Normally, when the ignition switch 11 is off, the main relay MR is off, and so the VB voltage is not supplied to the electronic control device 1. However, the BATT voltage of the in-vehicle battery 10 is input to the power supply IC2 through the BATT terminal T2. The power supply IC2 inputs the BATT voltage to the overcurrent detection counter 4. This allows the overcurrent detection counter 4 to operate at all times, regardless of whether the main relay MR is on or off. However, the overcurrent detection counter 4 will not count up unless an overcurrent flows through the current detection resistor R.

[0020] Thereafter, when the ignition switch 11 is turned on by a user operation, the main relay MR is turned on. As a result, the VB voltage is supplied to the supply line 13 inside the electronic control device 1. When the VB voltage is supplied to the supply line 13, noise is removed by a noise filter made up of capacitors C1 and C2 and inductor L1, and the voltage is supplied to the switching elements M1 and M2 through a current detection resistor R. When the power supply IC2 is started, the pre-drivers 6 and 7 complementarily drive the switching elements M1 and M2 to start supplying power to the control circuit 20 through the power supply terminal T3.

[0021] Next, the operation will be described when the power supply terminal T3 is short-circuited to ground. When the power supply terminal T3 is dead shorted, a large current flows through the VB voltage supply line 13 while the switching element M1 is on. Since a large current flows through the current detection resistor R, the overcurrent detection circuit 3 increments the count number of the overcurrent detection counter 4 at timing t1 when the current flowing through the current detection resistor R exceeds a predetermined overcurrent threshold.

[0022] Even if overcurrent detection counter 4 counts at timing t1, an overcurrent continues to flow through supply line 13. Due to the effect of the dead short, the VB voltage itself drops and when it reaches the reset threshold of power supply IC2, power supply IC2 is reset at timing t2.

[0023] Thereafter, when the VB voltage returns to the predetermined start-up threshold, power supply IC2 inputs the start-up threshold voltage and restarts at timing t3. If the dead short at power supply terminal T3 continues even when power supply IC2 restarts, and the overcurrent state continues, the current flowing through supply line 13 at timing t4 will exceed the overcurrent threshold.

[0024] At this time, because power is constantly being supplied to the overcurrent detection counter 4 through the BATT terminal T2, the overcurrent detection counter 4 can start counting from the number of counts measured before the power supply IC2 was reset. Furthermore, if the dead short is not eliminated even after the power supply IC2 is restarted, the VB voltage drops. Therefore, when the VB voltage reaches the reset threshold of the power supply IC2, the power supply IC2 is reset again at timing t5.

[0025] In this way, when power supply IC2 is repeatedly reset and restarted, overcurrent detection counter 4 counts up its measurement value each time this reset is repeated. At this time, if the measurement value of overcurrent detection counter 4 reaches a predetermined permanent overcurrent threshold, voltage adjustment operation by power supply IC2 is stopped at timing t6. Then, power supply IC2 stops permanently without restarting even if the VB voltage reaches the start-up threshold. Once power supply IC2 stops permanently, the voltage at VB terminal T1 returns to the normal voltage as shown after timing t8.

[0026] When the measurement value of the overcurrent detection counter 4 reaches a predetermined permanent overcurrent threshold, the voltage adjustment operation by the power supply IC 2 is stopped. At this time, it is desirable for the power supply IC IC 2 to continue stopping the voltage adjustment operation until the start-up operation switch detection circuit 5 detects that the start-up operation by the ignition switch 11 is turned on again.

[0027] When the ignition switch 11 is turned off at timing t9, the power supply IC 2 detects that the start-up operation is turned off by the start-up operation switch detection circuit 5, and resets the measurement value of the overcurrent detection counter 4 to the initial value.

[0028] Thereafter, when the ignition switch 11 is turned on, the power supply IC 2 detects the start-up operation-on by the start-up switch detection circuit 5, and restarts the voltage adjustment operation by the power supply IC 2. Then, the overcurrent detection counter 4 restarts counting from the initial value. At this time, if it is confirmed that the circuit has returned to normal from the dead short, the overcurrent detection counter 4 operates normally without counting the overcurrent, as shown after timing t10.

[0029] Figure 3 shows the operation when the dead short abnormality continues when the ignition switch 11 is on. As shown by timings t20 to t25 in Figure 3, if the dead short has not returned to normal when the ignition switch 11 is turned on, the overcurrent detection counter 4 starts counting the overcurrent, and when it reaches the permanent overcurrent threshold as described above, the voltage adjustment operation by the power supply IC2 is stopped. This ensures safety.

[0030] Figure 4 shows a time chart for the case where an overcurrent is detected momentarily, but the system returns to normal immediately thereafter. If the VB voltage exceeds the startup threshold of power supply IC2, and no current exceeding the overcurrent threshold is detected thereafter, power supply IC2 determines that a normal current has been detected, and resets the measurement value of overcurrent detection counter 4 at timing t30. As a result, even if an overcurrent is detected momentarily, if the system subsequently returns to normal, the measurement value of overcurrent detection counter 4 is reset.

[0031] <Summary of this embodiment> In contrast, in this embodiment, when an overcurrent flows and the VB voltage falls below a predetermined reset threshold, the power supply IC2 is reset, but the overcurrent detection counter 4 is not reset, and the power supply IC2 retains the measurement value of the overcurrent detection counter 4 before the reset.

[0032] By stopping the power supply, there is no voltage drop in the VB voltage supply line 13, and the power supply IC2 can resume operation. As a result, the measurement value of the overcurrent detection counter 4 is no longer cleared each time the power supply IC2 is reset, but is instead permanently held, and when this measurement value reaches the permanent overcurrent threshold, the power supply IC2 can stop restarting itself. In this case, power startup will not be permitted until the next time the ignition switch 11 is turned on. This makes it possible to protect the components.

[0033] <Comparative Example> Furthermore, if the BATT voltage, which is constantly connected to the in-vehicle battery 10, is used as the power supply voltage for the power supply IC2, the dark current will increase. For this reason, it is conceivable to use the VB voltage, which is supplied only when the electronic control device 1 is started, as the power supply for the overcurrent detection counter 4. However, with such a configuration, as shown in Fig. 5, the measurement value of the overcurrent detection counter 4 is reset every time the electronic control device 1 is restarted, and the permanent overcurrent threshold value is never reached, so that the power supply IC2 is repeatedly reset and restarted, which is not preferable.

[0034] <Summary of this embodiment> In this embodiment, by using the BATT voltage as the power supply voltage for the overcurrent detection counter 4, the measurement value of the overcurrent detection counter 4 can be held even if the power supply IC2 is reset. As a result, even after the power supply IC2 is reset, the measurement value of the overcurrent detection counter 4 can be continuously counted from before the reset. By using the BATT voltage, which does not allow a large current to flow and does not cause a voltage drop during an overcurrent, as the power supply for the overcurrent detection counter 4, it is possible to prevent repeated resets. This makes it possible to prevent an overcurrent from continuing to flow through the supply line 13 and prevent element damage.

[0035] (Other embodiments) The present invention is not limited to the above-described embodiment, and the following modifications and extensions are possible. The "start-up switch" is not limited to the ignition switch 11, but may be any start-up switch that starts the power supply from the power supply IC 2 when operated by the user.

[0036] Although the present disclosure has been described based on the embodiment, it is understood that the present disclosure is not limited to the embodiment or structure. The present disclosure also encompasses various modifications and modifications within the equivalent range. In addition, various combinations and forms, as well as other combinations and forms including only one element, more than one element, or less than one element, are also within the scope and concept of the present disclosure. [Explanation of symbols]

[0037] In the drawing, 1 is a vehicle electronic control device, 2 is a power supply IC (power supply circuit), 3 is an overcurrent detection circuit, 4 is an overcurrent detection counter, 8 is a power supply IC reset circuit (reset circuit), 10 is an on-board battery, 11 is an ignition switch (start operation switch), 12 is a power supply unit, and MR is a main relay (start switch).

Claims

1. a power supply circuit (2) that, when an operating voltage is supplied from an on-board battery (10) via a start switch (MR) of the vehicle, adjusts the operating voltage to a predetermined voltage and supplies the voltage to a load mounted on the electronic control device; The power supply circuit includes: an overcurrent detection circuit (3) for detecting whether an overcurrent occurs in a supply line (13) to which the operating voltage is supplied through a wiring resistor; a reset circuit (8) for resetting the power supply circuit itself when the operating voltage falls below a predetermined reset threshold; an overcurrent detection counter (4) that measures the number of times an overcurrent state is detected by the overcurrent detection circuit; The overcurrent detection counter is configured to receive the operating voltage directly from the vehicle battery without passing through the start switch, and holds the measured number of times regardless of the reset state of the power supply circuit.

2. The power supply circuit is configured to restart when returning from the reset state; If the overcurrent state continues even when the power supply circuit is restarted, 2. The electronic control device for a vehicle according to claim 1, wherein the overcurrent detection counter starts counting from the number of times measured before the power supply circuit was reset, and when a predetermined permanent overcurrent threshold is reached, stops the voltage adjustment operation by the power supply circuit.

3. A start-up detection unit (5) is provided for detecting whether a start-up operation is turned on or off by a start-up operation switch (11) for starting a vehicle, 2. The electronic control device for a vehicle according to claim 1, wherein if the voltage adjustment operation by the power supply circuit is stopped when the measured value of the overcurrent detection counter exceeds a predetermined threshold, the voltage adjustment operation by the power supply circuit continues to be stopped until the start-up detection unit detects that the start-up operation is turned on again.

4. A start-up detection unit (5) is provided for detecting whether a start-up operation is turned on or off by a start-up operation switch (11) for starting the vehicle, 2. The electronic control device for a vehicle according to claim 1, wherein when the start-up detection unit detects that a start-up operation is off, the measured value of the overcurrent detection counter is reset to an initial value, and when the start-up detection unit detects that a start-up operation is on, the voltage adjustment operation by the power supply circuit is restarted, and the counting by the overcurrent detection counter is resumed from the initial value.

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