JP6695244B2 - Power control device - Google Patents

Description

  The present invention relates to a power supply control device that controls power supply to an electric load in a control unit for an automobile, for example.

  In recent years, the demand for reducing the current consumption value (dark current) of the battery when the ignition of the automobile is off has become strict, and the need for reducing the dark current of the automobile control unit has increased. For example, in Patent Document 1, when the input circuit detects the ON state of the operation switch, the drive switching element of the electric load is turned off, and the current is interrupted between the power supply and the control unit, and between the control unit and the ground. The switching element for use is turned off. In addition, an overcurrent detection circuit, an overheat detection circuit, and the like are used to perform abnormality diagnosis during energization, the detection result is output to a protection circuit, and the current and temperature are adjusted by controlling the gate voltage of the drive switching element.

JP 2004-248093 A

  However, when the operation switch is in the OFF state, all the power supply paths except the input circuit are cut off, and the failure diagnosis function does not operate, so that the ON failure of the drive switching element cannot be detected. For this reason, a dark current may continue to flow through the drive switching element that has failed to turn on, which may shorten the battery life. Moreover, if a failure occurs when the power is not supplied, in order to carry out a failure diagnosis, it is necessary to supply power through the failed element, which may cause an overcurrent or overheat to the electric load.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to make it possible to perform a failure diagnosis in a state where a power supply path is cut off. Another object of the present invention is to provide a power supply control device capable of reducing the above.

A power supply control device of the present invention is provided in a power supply path to an electric load, and a first power cutoff circuit that switches the power supply path to a conductive state or a cutoff state based on a start request signal of the electric load; No. 1 power supply interruption circuit is provided in the power supply path between the electric load and the power supply path based on the start request signal and the voltage level of the power supply path downstream of the first power cutoff circuit. And a second power cutoff circuit for switching between a conductive state and a cutoff state, the second power cutoff circuit is provided in the power supply path on the downstream side of the first power cutoff circuit, and receives a control signal from the outside. On the basis of the above, an external control circuit unit that maintains a conductive state of the power supply path during normal operation and puts the power supply path into a cutoff state when a cutoff request is made by the control signal; It is detected that the voltage level of the power supply path, which is provided on the power supply path between the electric load and the electric load, is higher than a predetermined value based on the activation request signal. In this case, a signal indicating a failure of the first power cutoff circuit is output to the outside, and when the start is requested by the start request signal, the power supply between the external control circuit unit and the electric load is And a monitor circuit section for electrically connecting the supply path .

According to the present invention, when the non-operation of the electric load is instructed by the start request signal of the electric load, the interruption operation is performed by the first power interruption circuit, so that the power supply path to the electric load is interrupted and dark. The current can be reduced. The second power cutoff circuit switches the power supply path to the conductive state or the cutoff state based on the start request signal and the voltage level of the power supply path on the downstream side of the first power cutoff circuit. The failure diagnosis of the first power cutoff circuit can be performed by the two power cutoff circuit. Then, when the voltage level of the power supply path is higher than a predetermined value and a failure is detected when the power supply path is in the cutoff state in the first power cutoff circuit, the first power cutoff circuit is in the second power cutoff circuit. The power supply path on the downstream side of is cut off.
Therefore, the failure diagnosis can be performed with the power supply path cut off, and the dark current at the time of failure can be reduced not only when the non-operation of the electric load is instructed by the start request signal during normal operation.

It is a circuit diagram of a power supply control device according to an embodiment of the present invention. 3 is a flowchart showing a schematic operation of the power supply control device shown in FIG. 1. 6 is a flowchart showing another schematic operation of the power supply control device shown in FIG. 1.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows a circuit configuration example of a power supply control device, which controls a power supply supplied to an electric load in a vehicle control unit. This power supply control device includes a power cutoff circuit 1 (first power cutoff circuit), a power cutoff circuit 2 having a failure diagnosis function (second power cutoff circuit), an electric load 3, and control circuit elements included in the electric load 3. A power cutoff circuit 4 (third power cutoff circuit) that cuts off the electric path when the polarity of the battery terminal is reversely connected by control is provided.

  The power cutoff circuit 1 includes a P-channel MOSFET 11, an NPN bipolar transistor 21 and resistors R1 to R4. The current path between the source and drain of the MOSFET 11 is inserted in the power supply path 10 from the battery terminal T1 to the electric load 3. That is, the source of the MOSFET 11 is connected to the battery terminal T1, and the resistor R1 is connected between the gate and the source. One end of the resistor R2 is connected to the gate of the MOSFET 11 and the other end is connected to the collector of the bipolar transistor 21. The base of the bipolar transistor 21 is connected to the ignition terminal T2 via the resistor R3, and the emitter is grounded. A resistor R4 is connected between the base and emitter of the bipolar transistor 21. A battery power supply BATT is supplied to the battery terminal T1, and an ignition signal IGN which is a start request signal for the electric load 3 in the vehicle control unit is input to the ignition terminal T2.

The power cutoff circuit 2 includes an external control circuit unit 2a that switches the power supply path 10 to a conductive state or a cutoff state based on a control signal CS input to the external control terminal T3, and a power supply path downstream of the power cutoff circuit 1. The monitor circuit section 2b for monitoring the voltage of 10 is provided.
The external control circuit unit 2a is provided in the power supply path 10 on the downstream side of the power cutoff circuit 1, maintains a conductive state during normal operation, and cuts off the power supply path 10 when a cutoff request is issued by the control signal CS. To The external control circuit section 2a is composed of P-channel type MOSFETs 12 and 14, N-channel type MOSFETs 17 and 18, and resistors R5 to R10.

  The source of the MOSFET 12 is connected to the drain of the MOSFET 11, and the drain is connected to the source of the MOSFET 13. The resistor R5 is connected between the gate and the source of the MOSFET 12. Further, one end of the resistor R6 is connected to the gate of the MOSFET 12, and the other end is connected to the drain of the MOSFET 18. The source of the MOSFET 18 is grounded, and the resistor R7 is connected between the gate and the source.

  One end of the resistor R8 is connected to the drain of the MOSFET 11 and the other end is connected to the source of the MOSFET 14. The gate of the MOSFET 14 is commonly connected to the gate of the MOSFET 17, and is also connected to the external control terminal T3 to which the control signal CS is input via the resistor R20. The drain of the MOSFET 14 is connected to the gate of the MOSFET 18 and the drain of the MOSFET 17 via the resistor R9. The source of the MOSFET 17 is grounded, and the resistor R10 is connected between the gate and the source.

  The monitor circuit unit 2b controls the MOSFET 13 when the voltage level of the power supply path 10 on the downstream side of the power cutoff circuit 1 becomes higher than a predetermined value when the power supply path 10 is cut off in the power cutoff circuit 1. Then, the power supply path 10 is shut off, and the monitor signal MS indicating the failure of the power shutoff circuit 1 is output from the external monitor terminal T4. If the ignition signal IGN indicates that the ignition is on, the MOSFET 13 is controlled to make the power supply path 10 conductive. The monitor circuit section 2b is composed of an NPN type bipolar transistor 22, P channel type MOSFETs 15 and 16 and resistors R11 to R17.

  One end of the resistor R11 is connected to the drain of the MOSFET 12, and the other end is connected to the collector of the bipolar transistor 22 via the resistor R12. The emitter of the bipolar transistor 22 is grounded, and the base is connected to the ignition terminal T2 via the resistor R13. A resistor R14 is connected between the base and emitter of the bipolar transistor 22. The source of the MOSFET 15 is connected to the drain of the MOSFET 12, and the gate is connected to the connection point of the resistors R11 and R12. The drain of the MOSFET 15 is connected to the gate of the MOSFET 16 and is grounded via the resistor R15.

  The source of the MOSFET 16 is connected to the drain of the MOSFET 12, and the drain is grounded via the resistor R16 and is connected to the external monitor terminal T4 via the anode and cathode of the diode D1. A resistor R17 is connected between the gate and the source of the MOSFET 16.

  The MOSFET 13, the resistors R18 and R19, and the diode D2 make the power supply path 10 conductive or cut off based on the output voltage VA of the monitor circuit unit 2b and the voltage level of the power supply path 10 on the downstream side of the power cutoff circuit 1. It is to switch. Further, when the power supply cutoff circuit 1 cuts off the power supply path 10, the monitor circuit section 2b detects that the voltage level of the power supply cutoff path 10 downstream of the power supply cutoff circuit 1 becomes higher than a predetermined value. In this case, the power supply path 10 on the downstream side of the power cutoff circuit 1 is cut off.

The source of the MOSFET 13 is connected to the drain of the MOSFET 12, and the gate is grounded via the resistor R18. A resistor R19 is connected between the gate and the source of the MOSFET 13. The anode of the diode D2 is connected to the drain of the MOSFET 16 and the anode of the diode D1, and the cathode is connected to the gate of the MOSFET 13.
The electric load 3 includes a load 5, a power supply IC 6, a driver IC 7, a control circuit element microcomputer 8 and a smoothing capacitor 9. The power supply IC 6 and the driver IC 7 are controlled by the microcomputer 8.

The power cutoff circuit 4 (third power cutoff circuit) is provided in the power supply path 10 between the power cutoff circuit 2 and the electric load 3. The power cutoff circuit 4 includes a P-channel MOSFET 19, an NPN bipolar transistor 23, and resistors R21 to R24. The drain of the MOSFET 19 is connected to the drain of the MOSFET 13, and the gate is connected to the collector of the bipolar transistor 23 via the resistor R21. A resistor R22 is connected between the gate and the source of the MOSFET 19, and one electrode of the smoothing capacitor 9, the power supply IC 6, the driver IC 7, and the load 5 are connected to the source. The base of the bipolar transistor 23 is connected to the microcomputer 8 via the resistor R23, and the emitter is grounded. A resistor R24 is connected between the base and the emitter of the bipolar transistor 23.
The diodes D11 to D19, whose anodes and cathodes are respectively connected between the drains and sources of the MOSFETs 11 to 19, are parasitic diodes.

  A schematic operation of the power supply control device shown in FIG. 1 will be described with reference to the flowchart of FIG. In the initial state, the ignition signal IGN, which is a start request signal for the electric load 3, is on standby at a low level (ignition off) (step S1), and the power cutoff circuit 1 is in a cutoff state (step S2). In this state, the power cutoff circuit 2 makes a failure diagnosis whether the power cutoff circuit 1 is reducing the dark current (whether the dark current is flowing). When the ignition signal IGN is at a low level, the failure diagnosis is performed when the monitor circuit section 2b monitors the voltage of the power supply path 10 on the downstream side of the power cutoff circuit 1 and the power cutoff circuit 1 cuts off the power supply path 10. In addition, when the voltage level of the power supply path 10 becomes higher than a predetermined value, the power cutoff circuit 2 is controlled to cut off the power supply path 10 and a high level monitor signal MS indicating a failure of the power cutoff circuit 1 is output. Output (step S3).

  When it is determined by the diagnosis of the power cutoff circuit 2 that there is no failure (at this time, the monitor signal MS is low level), normal operation is started. First, the ignition signal IGN is turned on to supply the battery power BATT to the electric load 3 (step S4). When the ignition is turned on, the power cutoff circuit 1 becomes conductive (step S5), and the power cutoff circuit 2 also becomes conductive (step S6). As a result, the battery power supply BATT is supplied from the battery terminal T1 to the electric load 3 via the power supply cutoff circuit 1 and the power supply cutoff circuit 2 (step S7). When the ignition is turned off, the cutoff states of the power cutoff circuit 1 and the power cutoff circuit 2 are maintained, and the process returns to step S1.

When the ignition signal IGN goes low, the operation ends (step S8), both the power cutoff circuit 1 and the power cutoff circuit 2 are cut off, and the process returns to step S1.
On the other hand, when it is determined in step S3 that the power cutoff circuit 1 has a failure due to the diagnosis of the power cutoff circuit 2 and dark current is flowing, the monitor signal MS is set to a high level to notify the outside (step S9). Then, the power supply cutoff circuit 2 is turned off to cut off the power supply, and the process ends (step S10).

  According to the power supply control device having the above-described configuration and operation, when the ignition signal IGN indicates that the ignition is off (non-operation), the power supply cut-off circuit 1 causes the power supply to the electric load 3 to shut off. The dark current can be reduced by shutting off the supply path 10. Further, the power cutoff circuit 2 switches the power supply path 10 to the conductive state or the cutoff state based on the ignition signal IGN and the voltage level of the power supply path 10 on the downstream side of the power cutoff circuit 1 by the monitor circuit section 2b. Therefore, the failure diagnosis of the power cutoff circuit 1 can be performed by the power cutoff circuit 2. Then, when the voltage level of the power supply path 10 becomes higher than a predetermined value when the power supply path 10 in the power supply cutoff circuit 1 is in the cutoff state, the power supply cutoff circuit 2 supplies power to the downstream side of the power supply cutoff circuit 1. The route 10 is cut off. Therefore, the failure diagnosis can be performed in the state where the power supply path 10 is cut off, and the dark current at the time of failure can be reduced not only when the ignition signal IGN is instructed to turn off the ignition in the normal state.

FIG. 3 shows a modification of the operation shown in FIG. In FIG. 2, when it is determined in step S9 that a dark current is flowing in the power supply path 10, the monitor signal MS is set to a high level to notify the outside that a failure has occurred in the power cutoff circuit 1. I did it. On the other hand, when the monitor signal MS becomes high level and it is detected that the power cutoff circuit 1 is out of order, the high level control signal CS is input to the external control terminal T3 (step S11), and the external control is performed. The circuit section 2a is turned off (step S12).
Other operations are substantially the same as those in the flowchart shown in FIG. 2, and thus detailed description will be omitted.
In this way, when the monitor signal MS detects that the power cutoff circuit 1 is out of order, the external control circuit unit 2a is forcibly cut off by the control signal CS, thereby reliably suppressing the dark current. it can.

Next, the operation of the power supply control device shown in FIG. 1 will be described in detail.
[During normal operation]
When the ignition signal IGN becomes high level and the ignition on is instructed, the base-emitter voltage of the bipolar transistors 21 and 22 becomes high, and both of these transistors are turned on. When the bipolar transistor 21 is turned on, a potential difference is generated between the gate and the source of the MOSFET 11, and the MOSFET 11 is turned on. When the MOSFET 11 is turned on, a voltage is applied to the source side of the MOSFET 12.

  The external control terminal T3 is basically a terminal used only when a failure occurs, and the control signal CS is normally at a low level (0V). Therefore, the MOSFET 14 is turned on and the MOSFET 17 is turned off. As a result, the MOSFET 18 is turned on. When the MOSFET 18 turns on, the MOSFET 12 turns on, a voltage is applied to the source side of the MOSFET 13, and the MOSFET 13 turns on. In this way, by turning on the MOSFET 11, MOSFET 12, and MOSFET 13, the battery power supply BATT is supplied to the monitor circuit unit 2b and the electric load 3 side via the power supply path 10.

At this time, since the bipolar transistor 22 is turned on, the MOSFET 15 is turned on, and the MOSFET 16 is turned off by turning on the MOSFET 15. Since the MOSFET 16 is off, the voltage VA becomes low level, the monitor signal MS output from the external monitor terminal T4 becomes low level, and no abnormality is detected from the outside.
The dark current is diagnosed when the ignition is off, and the voltage is not detected (no diagnosis) during normal operation.

[When the ignition is off (normal)]
When the ignition signal IGN goes low, the ignition is turned off. The bipolar transistor 21 is turned off, the MOSFET 11 is turned off, and the power cutoff circuit 1 cuts off the power supply path 10. Therefore, only a minute leak current of the MOSFET 11 flows on the drain side of the MOSFET 11.

As shown in the circuit block of FIG. 1, by interposing the power cutoff circuit 1 in the power supply path 10 for the microcomputer 8 and the load 5 side, which consume large current in the automobile control unit, the current flowing at the time of ignition off is reduced. Since only the leak current of the MOSFET 11 can be used, the dark current can be significantly reduced.
Further, when the ignition is turned off, only the leak current of the MOSFET 11 flows to the drain side of the MOSFET 11, so that the voltage VA is at a low level and the monitor signal MS is also at a low level, so that no abnormality is detected by the external monitor terminal T4.

[When ignition is off (when MOSFET 11 is on failure)]
Since the MOSFET 11 is turned off when the ignition is turned off, no voltage is applied to the drain side of the MOSFET 11, but stress is applied because the voltage of the battery power source BATT is always applied to the source side. Therefore, consider a case where the MOSFET 11 has an ON failure for some reason.
When the MOSFET 11 fails to turn on, the voltage level of the power supply path 10 on the drain side (downstream side) of the MOSFET 11 rises even if the ignition is off.

  Since no failure (abnormality) is detected in the first stage, the control signal CS remains at the low level (0V). As in the normal operation, the MOSFET 12 is turned on and the battery power BATT is supplied to the drain side. When the ignition is off, the bipolar transistor 22 is off. When the bipolar transistor 22 is off, the MOSFET 15 is off and the MOSFET 16 is on. As a result, the level of the voltage VA rises, the level of the external monitor terminal T4 rises, and the monitor signal MS goes high. Further, when the level of the voltage VA rises, the potential difference between the gate and the source of the MOSFET 13 disappears, so that the MOSFET 13 is forcibly turned off. Therefore, the power supply path 10 can be shut off while notifying the abnormality to the outside by the monitor signal MS. As described above, the abnormality can be detected without depending on the microcomputer 8 and the diagnostic circuit inside the electric load 3 while having the configuration capable of reducing the dark current.

At this time, since the control signal CS is low level (0 V), the MOSFET 14 is on, the MOSFET 17 is off, and the MOSFET 18 is on. When the MOSFET 18 is turned on, the MOSFET 12 is turned on and the battery power source BATT is supplied to the source side of the MOSFET 13. However, when the ignition is off, the bipolar transistor 22 is off, so the MOSFET 15 is off and the MOSFET 16 is on.
When the MOSFET 16 is turned on, the level of the voltage VA becomes substantially equal to the source side of the MOSFET 13, so that the MOSFET 13 is turned off and the power supply path 10 is cut off.

  When an abnormality is detected at the external monitor terminal T4, the high-level control signal CS is input from the external control terminal T3 as described in the flowchart of FIG. It turns on and the MOSFET 18 turns off. As a result, the MOSFET 12 is turned off, and the supply of the battery power BATT can be forcibly cut off regardless of whether the ignition is on or off.

  As described above, the power supply control device of the present invention includes the power supply cutoff circuit 1 for reducing the dark current, the power supply cutoff circuit 2 for performing the failure diagnosis of the power supply cutoff circuit 1, and serving as the redundant circuit at the time of the failure. Equipped with. The dark current can be greatly reduced by providing the power cutoff circuit 1 for a control circuit element or load that consumes a large amount of current in the vehicle control unit. Further, since the power cutoff circuit 2 enables the failure diagnosis of the power cutoff circuit 1 when the ignition is turned off, even if the power cutoff circuit 1 fails, the power is supplied to the control circuit elements in the vehicle control unit. In other words, in other words, it is possible to diagnose the failure and shut off the power supply path 10 without increasing the current consumption.

Since the purpose of this circuit is to reduce the dark current, the power supply path 10 to the inside of the vehicle control unit is completely shut off when the ignition is turned off. Therefore, failure diagnosis by the microcomputer 8 inside the control unit is impossible.
However, even if the power cutoff circuit 1 fails when the ignition is turned off, the power cutoff circuit 2 can cut off the control circuit element in the control unit and the power supply path on the load side. Further, the level of the voltage VA inside the power cutoff circuit 2 becomes a high level only when the ignition 11 is turned off and the MOSFET 11 is turned on. Therefore, the failure of the power cutoff circuit 1 can be externally diagnosed.
Furthermore, when an abnormality is detected externally, the power supply path can be cut off regardless of whether the ignition is on or off without supplying power to the control circuit element in the control unit.

  Therefore, according to the present invention, when the non-operation is instructed by the activation request signal of the electric load, the interruption operation is performed by the first power interruption circuit, so that the power supply path to the electric load is interrupted and the dark current is cut off. Can be reduced. Further, the second power cutoff circuit operates in response to the operation of the first power cutoff circuit, and the failure diagnosis of the first power cutoff circuit can be performed by the second power cutoff circuit. Therefore, when a failure occurs in the first power supply cutoff circuit, it is possible to diagnose the failure and cut off the power supply path without supplying power to the electric load side.

Furthermore, the above-mentioned circuit configuration also provides the following effects (a) to (d).
(A) Since the abnormality of the first power shutoff circuit can be detected by the start request signal and the voltage level of the power supply path, it is possible to suppress the complication of the diagnostic processing.
(B) Since the circuit configuration can be cut off without performing a failure diagnosis by arithmetic processing, it is not necessary to constantly supply the power supply voltage to each element for diagnosis, and the dark current in the stopped state can be reduced.
(C) Since the abnormal state can be output to the outside (communication line with other ECU, inspection tool, etc.), the failing control based on the abnormality can be performed by the coordinated ECU. Further, it is possible to grasp the abnormal state of the power supply control device in the non-starting state.
(D) It can be shut off from an activated external ECU or the like, and can be shut off without activating the power supply control device.

  Although the present invention has been described using the embodiments, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the invention at the implementation stage. Further, the embodiments include inventions at various stages, and various inventions can be extracted by appropriately combining a plurality of disclosed constituent elements. For example, even if some constituent elements are deleted from all the constituent elements shown in the embodiment, at least one of the problems described in the section of the problem to be solved by the invention can be solved, and it is described in the section of the effect of the invention. When at least one of the effects is obtained, the configuration in which this constituent element is deleted can be extracted as the invention.

  DESCRIPTION OF SYMBOLS 1 ... 1st power supply cutoff circuit, 2 ... 2nd power supply cutoff circuit, 2a ... External control circuit part, 2b ... Monitor circuit part, 3 ... Electric load, 4 ... 3rd power supply cutoff circuit, 5 ... Load, 6 ... Power supply IC , 7 ... Driver IC, 8 ... Microcomputer (control circuit element), 9 ... Smoothing capacitor, 10 ... Power supply path, 11-16, 19 ... P-channel MOSFET, 17, 18 ... N-channel MOSFET, 21- 23 ... NPN bipolar transistor, R1 to R23 ... Resistor, T1 ... Battery terminal, T2 ... Ignition terminal, T3 ... External control terminal, T4 ... External monitor terminal, BATT ... Battery power supply, IGN ... Ignition signal (start request signal), CS ... control signal, MS ... monitor signal

Claims (4)

A first power cutoff circuit which is provided in a power supply path to the electric load and switches the power supply path to a conductive state or a cutoff state based on a start request signal of the electric load;
The power supply is provided in the power supply path between the first power cutoff circuit and the electric load, and the power supply is based on the start request signal and the voltage level of the power supply path downstream of the first power cutoff circuit. A second power cutoff circuit for switching the supply path to a conductive state or a cutoff state,
The second power cutoff circuit is provided in the power supply path on the downstream side of the first power cutoff circuit, and maintains the conductive state of the power supply path during normal operation based on a control signal from the outside. The start request signal is provided in an external control circuit unit that puts the power supply path into a cutoff state when a cutoff request is made by a control signal, and the power supply path between the external control circuit unit and the electric load. Based on the above, when it is detected that the voltage level of the power supply path on the downstream side of the external control circuit unit becomes higher than a predetermined value, a signal indicating a failure of the first power cutoff circuit is output to the outside. However, when the activation is instructed by the activation request signal, a monitor circuit unit for electrically connecting the power supply path between the external control circuit unit and the electric load, Control device. Further comprising a third power cutoff circuit provided in the power supply path between the downstream side of the second power cutoff circuit and the electric load,
The electric load includes a control circuit element that operates in response to the activation request signal,
The power supply control device according to claim 1, wherein the third power cutoff circuit is controlled by the control circuit element. The electric load is a vehicle control unit,
The control circuit element is a microcomputer,
The power supply control device according to claim 2, wherein the activation request signal is an ignition signal. The first power cutoff circuit includes a first transistor having a current path inserted in the power supply path,
The second power cutoff circuit includes second and third transistors whose current paths are inserted in series in the power supply path downstream of the first power cutoff circuit,
The third power cutoff circuit includes a fourth transistor having a current path inserted in the power supply path between the second power cutoff circuit and the electric load,
The power supply control device according to claim 2 , wherein the power supply path is switched between a conductive state and a cutoff state by controlling ON / OFF of each of the first to fourth transistors.