JP6847181B1 - In-vehicle control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an in-vehicle control device capable of quickly discharging the residual charge of a smoothing capacitor without using an external load. SOLUTION: One or more DC conversion circuits 11, a system IC 12 driven by a DC conversion circuit, an opening / closing circuit 13 inserted in series in an electric circuit connecting the DC conversion circuit and the system IC, and an opening / closing circuit. A smoothing capacitor 14 connected to the system IC, a discharge circuit 15 having a constant current discharge circuit 15b connected in parallel with the smoothing capacitor, and a low voltage for detecting that the input voltage is below the voltage threshold. It includes a detection circuit 16 and a control circuit 17 that sends a reset instruction to the system IC, a cutoff instruction to the switching circuit, and a discharge instruction to the discharge circuit when the input voltage is equal to or lower than the voltage threshold value. When the discharge circuit receives the discharge instruction, the constant current circuit of the discharge circuit is activated to discharge the residual charge of the smoothing capacitor via the discharge circuit. [Selection diagram] Fig. 1

Description

The present application relates to an in-vehicle control device.

Railroad vehicles, automobiles, and the like are equipped with in-vehicle control devices for controlling in-vehicle devices such as drive system motors. A system integrated circuit (hereinafter referred to as a system IC) composed of a microprocessor or the like is used in this in-vehicle control device. A system IC is designed so that in addition to the basic functions of a processor core, macro controller, etc., a semiconductor chip is equipped with integrated functions according to the purpose of use, and these functions work together to function as a system. It is an integrated circuit. This system IC defines a power supply sequence to be executed when the power is turned on and when the power is turned off in order to prevent problems such as latch-up when the power is turned on.

A smoothing capacitor is connected to the power supply terminal of the system IC for the purpose of stabilizing the voltage. A discharge resistor for discharging the electric charge remaining in the smoothing capacitor when the power supply is cut off is connected in parallel to this smoothing capacitor. The discharge resistance is set to a very large value in order to suppress power loss during normal operation of the control device. Therefore, it takes a long time to discharge the residual charge of the smoothing capacitor when the power supply is cut off.

In order to normally perform the power supply sequence when the power supply of the system IC is cut off, it is necessary to reduce the voltage of each power supply terminal of the system IC to almost zero in the order of the sequence. However, if it takes a long time to discharge the residual charge of the smoothing capacitor, the voltage of another power supply terminal to be reduced may be lowered before the voltage of one power supply terminal is lowered. If the power supply voltage drops in a different order than the sequence to be observed, the charge may remain in the circuit where the charge should not remain, or a backflow current may occur due to the reversal of the voltage. Therefore, a problem such as latch-up may occur when the power is cut off or when the power is turned on again. Therefore, in order to normally perform the power supply sequence when the power supply is cut off, it is necessary to quickly discharge the residual charge of the smoothing capacitor before the other power supply voltage drops.

As a method of quickly discharging the residual charge of the smoothing capacitor, in a control device equipped with an inverter circuit composed of a plurality of switching elements, some switching elements are turned on when the power is cut off to put the externally loaded motor in a torque-free state. A method of discharging the residual charge of the smoothing capacitor by driving with a smoothing capacitor is disclosed (see, for example, Patent Documents 1 and 2).

Japanese Unexamined Patent Publication No. 2005-253154 Japanese Unexamined Patent Publication No. 2018-152973

However, there is a problem that the conventional method of rapidly discharging the residual charge of the smoothing capacitor via an externally loaded motor cannot be used for an in-vehicle control device using a system IC.

The present application has been made to solve the above-mentioned problems, and an object of the present application is to obtain an in-vehicle control device capable of rapidly discharging the residual charge of a smoothing capacitor without using an external load.

In the vehicle-mounted control device according to the present application, one or a plurality of DC conversion circuits that convert DC input voltages into different voltages, and power output from the output terminals of one DC conversion circuit are input to the first power supply terminal. An on-off circuit inserted in series in the electric circuit connecting the system IC, the output terminal of one DC conversion circuit, and the second power supply terminal of the system IC, and connected between the on-off circuit and the second power supply terminal. A smoothing capacitor, a discharge circuit equipped with a constant current circuit connected in parallel with the smoothing capacitor, a low voltage detection circuit that detects that the DC input voltage has fallen below a preset voltage threshold, and a low voltage detection circuit. When it is detected that the DC input voltage is below the voltage threshold, a reset instruction is sent to the system IC, a cutoff instruction is sent to the switching circuit, and a discharge instruction is sent to the discharge circuit. It has. Then, the system IC is driven by the electric charge input to the first power supply terminal and performs arithmetic processing based on the voltage input to the second electric power supply terminal, and the discharge circuit issues a discharge instruction. When it is received, the constant current circuit of the discharge circuit is activated to discharge the residual charge of the smoothing capacitor to the ground.

In the in-vehicle control device of the present application, when the discharge circuit receives the discharge instruction, the constant current circuit is activated to discharge the residual charge of the smoothing capacitor to the ground, so that the residual charge of the smoothing capacitor is discharged without using an external load. It can be discharged quickly.

It is a block diagram of the vehicle-mounted control device which concerns on Embodiment 1. FIG. It is a block diagram of the constant voltage detection circuit of Embodiment 1. FIG. It is a block diagram of the discharge circuit of Embodiment 1. FIG. It is a timing chart in the vehicle-mounted control device of the first embodiment. It is a block diagram of the vehicle-mounted control device which concerns on Embodiment 1. FIG. It is a block diagram of the vehicle-mounted control device which concerns on Embodiment 2. FIG. It is a timing chart in the vehicle-mounted control device of the second embodiment. It is a block diagram of the vehicle-mounted control device which concerns on Embodiment 2. FIG.

Hereinafter, the in-vehicle control device according to the embodiment for carrying out the present application will be described in detail with reference to the drawings. In each figure, the same reference numerals indicate the same or corresponding parts.

Embodiment 1.
FIG. 1 is a configuration diagram of an in-vehicle control device according to the first embodiment. The in-vehicle control device of the present embodiment is mounted on, for example, an automobile, and has a function of controlling an engine, a brake, a transmission, and the like.

The vehicle-mounted control device 1 of the present embodiment shown in FIG. 1 includes a DC conversion circuit 11, a system IC 12, an on-off circuit 13, a smoothing capacitor 14, a discharge circuit 15, a low voltage detection circuit 16, and a control circuit 17. The DC conversion circuit 11 converts the DC input voltage Va into the first power supply voltage Vb1. The first power supply voltage Vb1 output from the DC conversion circuit 11 is input to the first power supply terminal 12a of the system IC 12. The switching circuit 13 is inserted in series in an electric line connecting the output terminal 11a of the DC conversion circuit 11 and the second power supply terminal 12b of the system IC 12. The smoothing capacitor 14 is connected between the switching circuit 13 and the second power supply terminal 12b. The discharge circuit 15 is connected in parallel to the smoothing capacitor 14. The low voltage detection circuit 16 detects that the DC input voltage Va is equal to or lower than a preset voltage threshold value. When the low voltage detection circuit 16 detects that the DC input voltage Va is equal to or lower than the voltage threshold, the control circuit 17 gives a reset instruction to the system IC 12, a cutoff instruction to the switching circuit 13, and a cutoff instruction. A discharge instruction is sent to the discharge circuit 15.

In the DC conversion circuit 11, the DC input voltage Va is input from an external DC power source 2 such as an in-vehicle battery via a relay 3. The DC conversion circuit 11 converts the DC input voltage Va into the first power supply voltage Vb1 and outputs the first power supply voltage Vb1 from the output terminal 11a to the switching circuit 13. Further, the output terminal 11a of the DC conversion circuit 11 is also connected to the first power supply terminal 12a of the system IC 12 and the power supply terminal 17a of the control circuit 17. Therefore, the electric power of the first power supply voltage Vb1 is the driving electric power of the system IC 12 and the control circuit 17. The DC conversion circuit 11 is a conversion circuit such as a series regulator or a switching regulator. The DC conversion circuit 11 may be another conversion circuit as long as it has a function of converting a DC input voltage into a different voltage and outputting it.

The system IC 12 is driven by the power of the first power supply voltage Vb1 supplied to the first power supply terminal 12a. The system IC 12 performs arithmetic processing based on the voltage input to the second power supply terminal 12b. The system IC 12 is an arithmetic processor such as a microcomputer or a System (System-on-a-Chip), and a power supply sequence is defined.

The switching circuit 13 is inserted in series into an electric line connecting the output terminal 11a of the DC conversion circuit 11 and the second power supply terminal 12b of the system IC 12, and connects the electric line based on the cutoff instruction sent from the control circuit 17. Electrically shut off. The switching circuit 13 is, for example, a transistor, a relay, or the like such as a MOS-FET (Metal-Oxide-Semiconductor Field-Effective Transistor), and has a function of electrically blocking and connecting an electric circuit. Here, the voltage on the output side of the switching circuit 13 is the voltage of the smoothing capacitor 14 and the voltage of the second power supply terminal 12b of the system IC 12. Hereinafter, the voltage on the output side of the switching circuit 13 is referred to as a first control voltage Vc1.

The smoothing capacitor 14 is connected between the switching circuit 13 and the second power supply terminal 12b, and has a function of smoothing the first control voltage Vc1 applied to the second power supply terminal 12b. The smoothing capacitor 14 is, for example, an aluminum electrolytic capacitor.

The discharge circuit 15 is connected in parallel to the smoothing capacitor 14, and has a function of discharging the residual charge of the smoothing capacitor 14 based on the discharge instruction sent from the control circuit 17. In the present embodiment, as shown in FIG. 1, the cutoff instruction sent by the control circuit 17 to the opening / closing circuit 13 and the discharge instruction sent to the discharge circuit 15 are the same first signal terminal 17b as the first operation instruction. It is a signal-based instruction.

A DC input voltage Va is input to the low voltage detection circuit 16. The low voltage detection circuit 16 detects that the DC input voltage Va is equal to or less than the preset voltage threshold Vth, and controls the voltage drop detection signal Vlow when the DC input voltage Va is equal to or less than the voltage threshold Vth. Output to the voltage signal terminal 17c of the circuit 17. The low voltage detection circuit 16 may be, for example, a reset IC or the like, and may be any other as long as it can detect that the DC input voltage Va is equal to or lower than the preset voltage threshold Vth. The voltage threshold Vth is, for example, the lower limit of the minimum operation guarantee voltage of the in-vehicle control device 1.

The control circuit 17 is driven by the power of the first power supply voltage Vb1 supplied to the power supply terminal 17a. When the control circuit 17 receives the voltage drop detection signal Vlow from the low voltage detection circuit 16, it outputs a reset instruction to the system IC 12 from the reset terminal 17d in order to start the power supply sequence of the system IC 12. Further, the control circuit 17 outputs a first operation instruction signal, which is a cutoff instruction to the open / close circuit 13 and a discharge instruction to the discharge circuit 15, from the first signal terminal 17b at the same timing as the reset instruction. .. In order to use the power of the first power supply voltage Vb1 as the driving power of the control circuit 17, the power supply terminal 17a of the control circuit 17 is connected to the DC conversion circuit 11, but the output of another power supply circuit is used as the driving power. Therefore, the power supply terminal 17a may be connected to another power supply circuit.

FIG. 2 is a configuration diagram of the low voltage detection circuit 16 of the present embodiment. The low voltage detection circuit 16 includes a voltage comparator 16a and six resistors 16b, 16c, 16d, 16e, 16f and 16g. The DC input voltage Va is divided by two resistors 16b and 16c and input to the non-inverting input terminal of the voltage comparator 16a. The voltage threshold Vth predetermined as the reference voltage of the low voltage detection circuit 16 is divided by the two resistors 16d and 16e and input to the inverting input terminal. The resistance values of the four resistors 16b, 16c, 16d and 16e are set so that the output is inverted when Va falls below a predetermined voltage threshold Vth as the reference voltage of the low voltage detection circuit 16. The voltage comparator 16a compares the voltage input to the non-inverting input terminal with the voltage input to the inverting input terminal, and when the DC input voltage Va becomes equal to or less than the voltage threshold Vth, the voltage comparator 16a refers to the control circuit 17. The voltage drop detection signal Vlow is output. The voltage drop detection signal Vlow is, for example, an off digital signal indicating no detection when the DC input voltage Va exceeds the voltage threshold Vth, and an ON digital signal indicating detection when the DC input voltage Va is equal to or less than the voltage threshold Vth. A resistor 16f is connected between the output terminal of the voltage comparator 16a and the inverting input terminal of the voltage comparator 16a. By feeding back the output of the output terminal of the voltage comparator 16a to the inverting input terminal of the voltage comparator 16a via the resistor 16f, the voltage input to the inverting input terminal can have a hysteresis width. That is, the voltage threshold Vth has a hysteresis width. Since the voltage threshold Vth has a hysteresis width, it is possible to prevent the output digital signal from chattering when the DC input voltage Va becomes a voltage close to the voltage threshold Vth due to the influence of noise, for example. The configuration of the low voltage detection circuit 16 is not limited to the configuration shown in FIG. 2, and other configurations may be used as long as it can detect that the DC input voltage Va is equal to or lower than the voltage threshold value Vth.

FIG. 3 is a configuration diagram of the discharge circuit 15 of the present embodiment. The discharge circuit 15 includes a backflow prevention element 15a, a constant current discharge circuit 15b, a delay circuit 15c, and a low-speed discharge resistor 15d. The constant current discharge circuit 15b includes a discharge switching element 31, a current value setting resistor 32, and a discharge drive resistor 33. The base terminal of the discharge switching element 31 is connected to the reference voltage Vo of the discharge circuit 15 via the discharge drive resistor 33. The collector terminal of the discharge switching element 31 is connected to the smoothing capacitor 14 via the backflow prevention element 15a. The emitter terminal of the discharge switching element 31 is connected to the ground via the current value setting resistor 32. The base terminal of the discharge switching element 31 is also connected to the delay circuit 15c. Since the constant current discharge circuit 15b is configured as an emitter follower and the base terminal is connected to a reference voltage Vo which is a DC voltage, the current flowing from the collector terminal to the emitter terminal becomes a constant current.
The backflow prevention element 15a receives the smoothing capacitor 14 from the discharge circuit 15 when the first control voltage Vc1 drops due to the discharge of the residual charge of the smoothing capacitor 14 and the first control voltage Vc1 becomes lower than the reference voltage Vo of the discharge circuit 15. Prevents the reverse current generated toward. The reference voltage Vo of the discharge circuit 15 is set by another power supply circuit that constantly supplies power.

Since the low-speed discharge resistor 15d is connected between the smoothing capacitor 14 and the ground, a current always flows through the low-speed discharge resistor 15d when the in-vehicle control device 1 is operating normally. Therefore, in order to minimize the power loss in the low-speed discharge resistor 15d, the resistance value of the low-speed discharge resistor 15d is set to a high resistance value of, for example, 100 KΩ or more. Therefore, when the residual charge of the smoothing capacitor 14 is discharged through the low-speed discharge resistor 15d, an extremely long time determined by the resistance value and the time constant of the capacitance value is required. On the other hand, the constant current discharge circuit 15b discharges the residual charge of the smoothing capacitor 14 at a constant current value determined by the reference voltage Vo and the resistance value of the current value setting resistance 32. Therefore, when the residual charge of the smoothing capacitor 14 is discharged by the constant current discharge circuit 15b, the voltage drops linearly. The current value flowing through the constant current discharge circuit 15b can be set to an arbitrary value from the capacitance value and the discharge time of the smoothing capacitor 14, and the discharge time is set to be a short time during which the sequence can be performed normally. ..

The delay circuit 15c is composed of a delay unit 34, a first discharge cutoff unit 35, and a second discharge cutoff unit 36. The delay unit 34 is composed of a resistor 34a and a capacitor 34b, and gives a preset delay time to the discharge instruction received from the control circuit 17. The first discharge cutoff unit 35 is composed of a discharge switch element 35a and a resistor 35b, and the second discharge cutoff unit 36 is composed of a discharge switch element 36a and a resistor 36b. A discharge instruction given a delay time by the delay unit 34 is input to the first discharge cutoff unit 35. A discharge instruction is directly input to the second discharge cutoff unit 36. The first discharge cutoff unit 35 and the second discharge cutoff unit 36 are connected in parallel to the base terminal of the discharge switching element 31 of the constant current discharge circuit 15b.

Next, the operation of the discharge circuit 15 of the present embodiment will be described.
When the discharge circuit 15 does not receive the discharge instruction from the control circuit 17, that is, when the connection instruction is issued to the switching circuit 13, a pull-down signal is output from the delay circuit 15c to the constant current discharge circuit 15b. At this time, since the base terminal of the discharge switching element 31 of the constant current discharge circuit 15b is pulled down, the collector terminal and the emitter terminal of the discharge switching element 31 are cut off. That is, the resistance of the constant current discharge circuit 15b is close to infinity. When the discharge circuit 15 receives the discharge instruction from the control circuit 17, the discharge instruction delayed by the delay circuit 15c is input to the constant current discharge circuit 15b. The voltage of the base terminal of the discharge switching element 31 of the constant current discharge circuit 15b is pulled up to the reference voltage Vo via the discharge drive resistor 33, and the collector terminal and the emitter terminal of the discharge switching element 31 are connected. Become. Then, the residual charge of the smoothing capacitor 14 flows to the ground via the backflow prevention element 15a, the discharge switching element 31, and the current value setting resistor 32. As described above, since the resistance value of the current value setting resistor 32 is set based on the discharge time required to comply with the power supply sequence when the power supply is cut off, the discharge via the constant current discharge circuit 15b is short. It will be done promptly. When the residual charge of the smoothing capacitor 14 is discharged via the constant current discharge circuit 15b and the first control voltage Vc1 becomes lower than the voltage of the base terminal of the discharge switching element 31, the discharge via the constant current discharge circuit 15b is performed. finish. After that, the discharge is performed via the low-speed discharge resistor 15d. However, the discharge via the low-speed discharge resistor 15d becomes slow.

FIG. 4 is a timing chart of the in-vehicle control device 1 of the present embodiment. FIG. 4 shows an operating state of the in-vehicle control device 1 in a state where the DC input voltage Va is decreasing.
For example, when the ignition switch of the vehicle is set to off and the relay 3 is opened, the DC input voltage Va gradually decreases. The low voltage detection circuit 16 detects that the DC input voltage Va is equal to or lower than the preset voltage threshold voltage Vth, and outputs a voltage drop detection signal Vlow to the control circuit 17. The control circuit 17 receives the voltage drop detection signal Vlow sent from the low voltage detection circuit 16 and outputs a reset instruction to the system IC 12. Further, the control circuit 17 outputs a first operation instruction signal which is a cutoff instruction to the open / close circuit 13 and a discharge instruction to the discharge circuit 15 at the same timing as the reset instruction. The opening / closing circuit 13 electrically cuts off the electric circuit in response to the first operation instruction signal which is a cutoff instruction. When the discharge circuit 15 receives the first operation instruction signal which is a discharge instruction, the smoothing capacitor 14 remains through the constant current discharge circuit 15b after the delay time preset by the delay circuit 15c of the discharge circuit 15 has elapsed. Discharge the charge.

The DC input voltage Va gradually decreases even after the voltage threshold Vth or less, and decreases to a voltage Vd at which the DC conversion circuit 11 cannot convert the DC input voltage into the first power supply voltage Vb1. As shown in the timing chart of the first power supply voltage Vb1 in FIG. 4, the DC conversion circuit 11 has the first power supply voltage until the DC input voltage Va becomes Vd or less even if the DC input voltage Va becomes the voltage threshold voltage Vth or less. Output Vb1. Therefore, the system IC 12 driven by the power of the first power supply voltage Vb1 can operate normally until the DC input voltage Va becomes Vd or less even if the DC input voltage Va becomes the voltage threshold Vth or less. The output voltage of the DC conversion circuit 11 gradually decreases after the DC input voltage Va becomes Vd or less.

The first control voltage Vc1 after the switching circuit 13 is cut off becomes the voltage of the residual charge of the smoothing capacitor 14. Therefore, the timing chart of the first control voltage Vc1 in FIG. 4 shows the voltage of the residual charge of the smoothing capacitor 14 after the switching circuit 13 is cut off. The discharge circuit 15 starts discharging the residual charge of the smoothing capacitor 14 at a timing delayed from the timing when the switching circuit 13 cuts off the electric circuit. At this time, the residual charge of the smoothing capacitor 14 is discharged via the constant current discharge circuit 15b, so that it is quickly discharged. The residual charge of the smoothing capacitor 14 is gradually discharged by the low-speed discharge resistor 15d after being discharged through the current value setting resistor 32.

When the discharge circuit receives the discharge instruction, the in-vehicle control device configured in this way drives the constant current circuit of the discharge circuit and discharges the residual charge of the smoothing capacitor with a constant current, so that smoothing is performed without using an external load. The residual charge of the capacitor can be discharged quickly. As a result, in this in-vehicle control device, the residual charge of the smoothing capacitor becomes almost zero before the power supply to the first power supply terminal of the system IC is reduced, so that the power supply sequence of the system IC at the time of power failure is ensured. Can be carried out.

Further, in the in-vehicle control device of the present embodiment, the residual charge of the smoothing capacitor is discharged via the constant current discharge circuit after the delay time preset in the delay circuit of the discharge circuit has elapsed, so that the power supply is cut off. Sometimes stable power sequence operation can be performed. For example, if the discharge operation of the discharge circuit is started before the switching circuit cuts off the electric circuit, the output current of the DC conversion circuit may increase sharply. As a result, the power supply sequence operation at the time of power failure becomes unstable, such as generation of unnecessary power when the power is cut off and ripple generation in the first control voltage which is the input of the second power supply terminal of the system IC. As described above, in the in-vehicle control device of the present embodiment, since the discharge operation of the discharge circuit is started after the opening / closing circuit performs the cutoff operation, a stable power supply sequence operation can be performed when the power supply is cut off.

Further, in the in-vehicle control device of the present embodiment, since the voltage threshold value Vth of the low voltage detection circuit can have a hysteresis width, the influence of chattering due to noise or the like can be minimized.

Further, since the residual charge of the smoothing capacitor is discharged via the constant current discharge circuit of the discharge circuit, the current at the time of discharge can be set to an arbitrary constant current value, so that the current value setting resistance 32 is allowed. An inexpensive resistor with low electric charge can be used.

FIG. 5 is a configuration diagram of another in-vehicle control device according to the present embodiment. Another vehicle-mounted control device shown in FIG. 5 includes a second DC conversion circuit 21 in parallel with the DC conversion circuit 11. The second DC conversion circuit 21 converts the DC input voltage Va into the second power supply voltage Vb2 and outputs it from the output terminal 21a. The output terminal 21a is connected to the first power supply terminal 12a of the system IC 12, and the second power supply voltage Vb2 serves as the driving power of the system IC 12. In the in-vehicle control device shown in FIG. 1, the power input to the first power supply terminal 12a of the system IC and the power input to the second power supply terminal 12b of the system IC 12 are the same outputs of the DC conversion circuit 11. I got it from. Like another in-vehicle control device shown in FIG. 5, the output of a DC conversion circuit in which the power input to the first power supply terminal 12a of the system IC 12 and the power input to the second power supply terminal 12b of the system IC 12 are different. May be obtained from.

The discharge circuit of the present embodiment includes a low-speed discharge resistor connected in parallel with the constant current discharge circuit, and the first control voltage Vc1 becomes lower than the voltage of the base terminal of the discharge switching element 31 to discharge the constant current. After the discharge operation of the circuit 15b is completed, the residual charge of the smoothing capacitor can be surely set to zero by discharging through the low-speed discharge resistor 15d. Therefore, it is possible to reliably execute the power supply sequence at the next power-on.

Embodiment 2.
FIG. 6 is a configuration diagram of the in-vehicle control device according to the second embodiment. The vehicle-mounted control device 1 of the present embodiment includes a plurality of DC conversion circuits. As shown in FIG. 6, the vehicle-mounted control device 1 of the present embodiment converts the DC input voltage Va into the second power supply voltage Vb2 in addition to the configuration of the vehicle-mounted control device shown in FIG. 1 of the first embodiment. A second switching circuit 23 inserted in series in the electric circuit connecting the second DC conversion circuit 21, the output terminal 21a of the second DC conversion circuit 21, and the first power supply terminal 12a of the system IC 12, and the second switching circuit. It includes a second smoothing capacitor 24 connected between the circuit 23 and the first power supply terminal 12a, and a second discharge circuit 25 connected in parallel to the second smoothing capacitor 24. In the vehicle-mounted control device 1 of the present embodiment, the DC conversion circuit 11 and the second DC conversion circuit 21 are connected in parallel. The second DC conversion circuit 21, the second open / close circuit 23, and the second discharge circuit 25 have the same configurations as the DC conversion circuit 11, the open / close circuit 13, and the discharge circuit 15, respectively.

The second DC conversion circuit 21 converts the DC input voltage Va into the second power supply voltage Vb2, and outputs the second power supply voltage Vb2 from the output terminal 21a to the second switching circuit 23. The second opening / closing circuit 23 electrically cuts off the electric circuit based on the cutoff instruction sent from the control circuit 17. The second discharge circuit 25 is connected in parallel to the second smoothing capacitor 24, and has a function of discharging the residual charge of the second smoothing capacitor 24 based on the discharge instruction sent from the control circuit 17. As shown in FIG. 6, the cutoff instruction sent by the control circuit 17 to the second opening / closing circuit 23 and the discharge instruction sent to the second discharge circuit 25 are the same second operation instruction signals output from the second signal terminal 17e. It is an instruction based on. In the present embodiment, the control circuit 17 outputs the second operation instruction signal with a delay with respect to the first operation instruction signal.

FIG. 7 is a timing chart of the in-vehicle control device 1 of the present embodiment. FIG. 7 shows the operating state of the in-vehicle control device 1 in a state where the DC input voltage Va is decreasing. In FIG. 7, the timing chart from the DC input voltage Va to the first control voltage Vc1 is the same as the timing chart described with reference to FIG. 4 of the first embodiment. The timing chart of the second power supply voltage Vb2 is substantially the same as the timing chart of the first power supply voltage Vb1. The control circuit 17 outputs a second operation instruction signal, which is a cutoff instruction to the second open / close circuit 23 and a discharge instruction to the second discharge circuit 25, at a timing delayed with respect to the first operation instruction signal. To do. The second opening / closing circuit 23 electrically cuts off the electric circuit in response to the second operation instruction signal which is a cutoff instruction. The second control voltage Vc2 after the second switching circuit 23 is cut off becomes the voltage of the residual charge of the second smoothing capacitor 24. Therefore, the timing chart of the second control voltage Vc2 in FIG. 7 shows the voltage of the residual charge of the second smoothing capacitor 24 after the second switching circuit 23 is cut off. The second discharge circuit 25 starts discharging the residual charge of the second smoothing capacitor 24 at a timing delayed from the timing when the second switching circuit 23 cuts off the electric circuit. At this time, the residual charge of the second smoothing capacitor 24 is discharged via the current value setting resistor of the constant current discharge circuit, so that the residual charge is quickly discharged. The residual charge of the second smoothing capacitor 24 is discharged through the current value setting resistor and then slowly discharged by the low-speed discharge resistor.

In the in-vehicle control device configured in this way, the first control voltage input to the second power supply terminal of the system IC is set before the second control voltage input to the first power supply terminal of the system IC drops. Since it falls down, it is possible to reliably carry out the power supply sequence of the system IC when the power supply is cut off.

Further, since the second control voltage input to the first power supply terminal of the system IC is surely lowered to zero in the second discharge circuit, the power supply sequence at the time of the next power-on can be surely executed.

FIG. 8 is a configuration diagram of another in-vehicle control device according to the present embodiment. The vehicle-mounted control device 1 shown in FIG. 8 has a first power supply voltage Vb1 which is an output voltage of the DC conversion circuit 11 in place of the input of the second DC conversion circuit 21 in place of the DC input voltage Va in the vehicle-mounted control device shown in FIG. It was done. In the vehicle-mounted control device shown in FIG. 6, the DC conversion circuit 11 and the second DC conversion circuit 21 are connected in parallel. On the other hand, in the in-vehicle control device shown in FIG. 8, the DC conversion circuit 11 and the second DC conversion circuit 21 are connected in series. The operation of the in-vehicle control device shown in FIG. 8 is the same as the operation of the in-vehicle control device shown in FIG.

In the in-vehicle control device configured in this way, the first control voltage input to the second power supply terminal of the system IC is set before the second control voltage input to the first power supply terminal of the system IC drops. Since it falls down, it is possible to reliably carry out the power supply sequence of the system IC when the power supply is cut off.

Although the present application describes various exemplary embodiments, the various features, embodiments, and functions described in one or more embodiments are limited to the application of the particular embodiment. Rather, it can be applied to embodiments alone or in various combinations.
Therefore, innumerable variations not illustrated are envisioned within the scope of the techniques disclosed in the present application. For example, it is assumed that at least one component is modified, added or omitted, and further, at least one component is extracted and combined with the components of other embodiments.

1 In-vehicle controller, 2 DC power supply, 3 relay, 11 DC conversion circuit, 12 system IC, 12a 1st power supply terminal, 12b 2nd power supply terminal, 13 switch circuit, 14 smoothing capacitor, 15 discharge circuit, 15a backflow prevention Element, 15b constant current discharge circuit, 15c delay circuit, 15d low speed discharge resistance, 16 low voltage detection circuit, 17 control circuit, 17a power supply terminal, 21 2nd DC conversion circuit, 23 2nd switch circuit, 24 2nd smoothing capacitor , 25 2nd discharge circuit, 31, 35a, 36a Discharge switching element, 32 Current value setting resistance, 33 Discharge drive resistance, 34 Delay part, 35 1st discharge cutoff part, 36 2nd discharge cutoff part.

Claims (5)

One or more DC conversion circuits that convert DC input voltages to different voltages,
A system IC in which the power output from the output terminal of one of the DC conversion circuits is input to the first power supply terminal, and
An on-off circuit inserted in series in an electric circuit connecting the output terminal of the DC conversion circuit and the second power supply terminal of the system IC, and an opening / closing circuit.
A smoothing capacitor connected between the switching circuit and the second power supply terminal,
A discharge circuit having a constant current circuit connected in parallel with the smoothing capacitor,
A low voltage detection circuit that detects that the DC input voltage has fallen below a preset voltage threshold value, and
When it is detected in the low voltage detection circuit that the DC input voltage is equal to or lower than the voltage threshold, a reset instruction is given to the system IC, a cutoff instruction is given to the opening / closing circuit, and the discharge circuit is given. It is an in-vehicle control device equipped with a control circuit that sends a discharge instruction to the device.
The system IC is driven by the power input to the first power supply terminal and performs arithmetic processing based on the voltage input to the second power supply terminal.
The discharge circuit is an in-vehicle control device characterized in that when it receives the discharge instruction, the constant current circuit of the discharge circuit is activated to discharge the residual charge of the smoothing capacitor via the discharge circuit. The vehicle-mounted control device according to claim 1, wherein the discharge circuit further includes a delay circuit that delays the discharge instruction received from the control circuit. The vehicle-mounted control device according to claim 1 or 2, wherein the discharge circuit further includes a backflow prevention element. The vehicle-mounted control device according to any one of claims 1 to 3, wherein the voltage threshold value of the low voltage detection circuit has a hysteresis width. A second switching circuit connected in series to an electric circuit connecting the first power supply terminal of the system IC and the output terminal of one DC conversion circuit.
A second smoothing capacitor connected between the second switching circuit and the first power supply terminal,
A second discharge circuit connected in parallel to the second smoothing capacitor is further provided.
The second discharge circuit is characterized in that the constant current circuit of the second discharge circuit is activated by a discharge instruction received from the control circuit to discharge the residual charge of the second smoothing capacitor via the second discharge circuit. The vehicle-mounted control device according to any one of claims 1 to 4.

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