WO2024018710A1

WO2024018710A1 - Power supply control circuit

Info

Publication number: WO2024018710A1
Application number: PCT/JP2023/015544
Authority: WO
Inventors: 智行河野; 賢佑伊藤
Original assignee: Ｋｙｂ株式会社
Priority date: 2022-07-20
Filing date: 2023-04-19
Publication date: 2024-01-25
Also published as: JP2024013588A

Abstract

The present invention maintains the normal operation of a vehicle even if noise is superimposed on a power supply voltage and suppresses the increase in the size of a device. A power supply control circuit 1a includes: input terminals T21, T22 to which a DC power supply can be connected; a power supply line that supplies power from the input terminals to a next-stage circuit; a coil L400 provided in the power supply line; a first capacitor C400 connected between the input terminal side of the coil L400 and the ground line for the power supply line; a second capacitor C401 connected between the next-stage circuit side of the coil L400 and the ground line; a switch element Q303 that is connected in series with the power supply line and turns on or off the supply of power to the next-stage circuit; a monitoring circuit U310 that turns off the switch element Q303 when the voltage or current of the power supply line exceeds a threshold value; and a semiconductor element including a diode connected in parallel with the coil such that the cathode faces the previous-stage side of the coil L400 and the anode faces the next-stage side of the coil.

Description

power control circuit

The present invention relates to a power supply control circuit.

An electronic control unit mounted on a vehicle is known (for example, Patent Document 1). The electronic control unit may include circuitry that controls the supply of power.

Japanese Patent Application Publication No. 2013-206802

In electronic control units mounted on vehicles, noise may be superimposed on the power supply voltage supplied to various parts. It is desirable to maintain normal vehicle operation even when noise is superimposed on the power supply voltage. However, even if the operation of the vehicle can be maintained normally, it is not preferable that the device becomes large.

The present disclosure has been made in view of the above, and the purpose is to provide a power supply that can maintain normal operation of a vehicle even when noise is superimposed on the power supply voltage, and that can suppress the increase in size of the device. The object of the present invention is to provide a control circuit.

In order to solve the above-mentioned problems and achieve the objects, a power supply control circuit according to an aspect of the present disclosure includes an input terminal to which a DC power supply can be connected, and a power supply line that supplies power from the input terminal to a subsequent circuit. , a coil provided on the power supply line, a first capacitor connected between the input terminal side of the coil and a ground line for the power supply line, and a first capacitor connected between the circuit side of the latter stage of the coil and the ground line. a second capacitor connected between the power supply line and the switch element connected in series with the power supply line to turn on or off the supply of power to the subsequent circuit; a monitoring circuit that turns off the switch element when the voltage is exceeded, and a diode connected in parallel with the coil such that the cathode faces the front side of the coil and the anode faces the rear side of the coil. A semiconductor element.

FIG. 1 is a diagram showing the configuration of a power supply control circuit according to a comparative example. FIG. 2 is a waveform diagram illustrating the operation of the power supply control circuit of the comparative example. FIG. 3 is a diagram showing the configuration of the power supply control circuit of the first embodiment. FIG. 4 is a waveform diagram illustrating the operation of the power supply control circuit of the first embodiment. FIG. 5 is a diagram showing the configuration of a power supply control circuit according to the second embodiment.

Hereinafter, embodiments of the power supply control circuit of the present disclosure will be described in detail based on the drawings. Note that the present invention is not limited to this embodiment. Furthermore, the constituent elements of each embodiment include those that can be easily replaced by those skilled in the art, or those that are substantially the same. Each embodiment is an illustrative example, and configurations shown in different embodiments can be partially replaced or combined. In the following description of each embodiment, the same or equivalent components as in other embodiments will be denoted by the same reference numerals, and the description thereof will be simplified or omitted. The configurations described below can be combined as appropriate. Further, the configuration can be omitted, replaced, or changed without departing from the gist of the present disclosure.

(Comparative example)
In order to facilitate understanding of the power supply control circuit of the present disclosure, a comparative example will be described first.

First, the configuration of a power supply control circuit according to a comparative example will be described. FIG. 1 is a diagram showing the configuration of a power supply control circuit 1 according to a comparative example. In FIG. 1, power supply control circuit 1 includes units U100, U200, U300, and U400. In the following explanation, when focusing on a certain unit, the left side in the figure may be referred to as the front stage, and the right side in the figure may be referred to as the rear stage.

Unit U100 includes a battery VBATT, which is a DC power source, and a coil L100. The battery VBATT is, for example, a 12 [V] or 24 [V] storage battery for a vehicle. That is, the normal voltage value output from the battery VBATT is 12 [V] or 24 [V]. Unit U200 in FIG. 1 and each unit on the right side thereof correspond to an ECU (Electronic Control Unit). An ECU is an electronic control unit installed in a vehicle or the like. In the following description, unit U200 and the units on the right side thereof may be collectively referred to as "ECU."

The unit U200 is provided after the unit U100 and before the unit U300. Unit U200 is provided to prevent failure of subsequent circuits even if the polarity of battery VBATT of unit U100 is accidentally reversed.

Unit U200 has capacitors C200 and C201, diodes D200 and D201, and terminals T21, T22, T23 and T24.

Terminals T21 and T22 are connected to terminals T11 and T12 of the preceding unit U100. Thereby, unit U100 and unit U200 are electrically connected. Terminals T21 and T22 are input terminals to which battery VBATT in unit U100 can be connected.

Capacitors C200 and C201 are charged by battery VBATT of unit U100. Current flows from unit U100 to unit U200 by battery VBATT and coil L100, and charges are accumulated in capacitor C200 and capacitor C201.

The diode D200 is provided to prevent reverse current flow. Diode D200 prevents current from flowing from unit U200 to unit U100.

If the polarity of the battery VBATT of the unit U100 is connected correctly, the diode D201 will be turned off. If the polarity of battery VBATT of unit U100 is accidentally reversed, diode D201 will turn on. This can prevent the subsequent unit U300 and the like from being broken.

Terminals T23 and T24 are connected to terminals T31 and T32 of the subsequent unit U300.

Unit U300 includes a current/voltage monitoring circuit U310, a switch element Q303, a resistor R320, and terminals T31, T32, T33, and T34. Resistor R320 is connected to the power line from unit U200 to unit U400. Resistor R320 is provided to detect the current and voltage of the power supply line. Switch element Q303 is connected to the above-mentioned power supply line. Switch element Q303 turns on or off the supply of power to the subsequent circuit.

The current and voltage monitoring circuit U310 is a circuit that monitors current and voltage. Current/voltage monitoring circuit U310 turns off switch element Q303 when detecting that the current flowing through resistor R320 exceeds a predetermined threshold. Furthermore, when detecting that the voltage across the resistor R320 exceeds a predetermined threshold, the current/voltage monitoring circuit U310 turns off the switch element Q303. That is, current/voltage monitoring circuit U310 turns off switch element Q303 when the voltage or current of the power supply line exceeds a threshold value. "Off" here includes not only completely turning off, but also limiting the current. For example, when an overcurrent is detected, the current is limited without turning off the switch element Q303 while keeping it conductive.

The switch element Q303 is a semiconductor switch such as an FET (Field Effect Transistor). Switch element Q303 is turned on or off depending on the voltage applied to the gate terminal of switch element Q303. Current/voltage monitoring circuit U310 turns on or off switch element Q303 by applying a voltage to the gate terminal of switch element Q303.

Unit U400 includes a diode D400, capacitors C400 and C401, a coil L400, and terminals T41, T42, T43, and T44. Unit U400 is provided for EMC (Electro Magnetic Compatibility) countermeasures. Capacitor C400, coil L400, and capacitor C401 function as a π-type filter for noise countermeasures. Since it functions as a π-type filter, it prevents noise from units preceding unit U400 from being input to the subsequent stage, and prevents noise from units following unit U400 from inputting to the previous stage.

Diode D400 functions as a freewheeling diode. The free circulation path IC1 is a path from the cathode of the diode D400, passing through the coil L400, the capacitor C401, and the ground line GND, and returning to the anode of the diode D400. If the diode D400 is not provided, and the voltage on the cathode side of the diode D400 drops to the negative side, the preceding switch element Q303 may be broken. Due to the diode D400, the voltage drop on the cathode side of the diode D400 stops at the forward voltage of the diode D400. Therefore, destruction of the switching element Q303 can be prevented. Note that the forward voltage is, for example, 0.7 [V].

A device (not shown) that operates in response to power supply is provided at the subsequent stage of the unit U400 (on the right side in the figure). Terminals T43 and T44 are electrically connected to a device provided downstream of unit U400. When the power supply control circuit 1 is mounted on a vehicle, it is conceivable that the electrical contact between the respective terminals may deteriorate due to vibrations during driving. Even in such a case, since the capacitor C401 is provided, the power supplied to each part can be stabilized. In other words, the capacitor C401 also has a function as a vibration countermeasure.

The path from terminal T21 via terminals T23, T31, T33, T41, and T43 is a power supply line that supplies power from terminal T21 to subsequent circuits. Coil L400 is connected to this power line. The capacitor C400 is connected to the input terminal side of the coil L400, that is, the terminal T41 side, and between the ground line GND and the power supply line. The capacitor C401 is connected on the circuit side after the coil L400, that is, on the terminal T43 side, between the power supply line and the ground line GND. The terminal T41 side is the upstream side of power supply through the power line when viewed from the coil L400. The terminal T43 side is on the downstream side of power supply through the power line when viewed from the coil L400. Note that the ground line GND is a path from the terminal T22 via the terminals T24, T32, T34, T42, and T44.

Next, the operation will be explained. The power supply control circuit 1 of the comparative example having the above configuration supplies power to each part of the device (not shown) on the right side of the unit U400, that is, at the subsequent stage. A device that receives power supply may be provided with a solenoid or a relay (not shown). Noise may be generated when turning solenoids or relays on or off. Furthermore, noise may occur due to load dump surge due to the relationship with a generator (not shown) for charging the battery VBATT, which is a DC power source. For convenience of explanation, these noises are expressed as noise VNOISE in the unit U100 in FIG.

Due to the occurrence of noise, the voltage of battery VBATT, that is, the voltage "+B" between terminals T21 and T22 changes. The operation when the voltage between terminals T21 and T22 changes will be described with reference to FIG. 2.

FIG. 2 is a waveform diagram illustrating the operation of the power supply control circuit 1 of the comparative example. In FIG. 2, the horizontal axis is time and the vertical axis is voltage. FIG. 2 shows the voltage of battery VBATT, that is, the voltage "+B" between terminals T21 and T22, the voltage "VL_IN" stored in capacitor C400, and the voltage "VL_OUT" stored in capacitor C401. Voltage VL_IN is the voltage on the input side of coil L400, and voltage VL_OUT is the voltage accumulated in capacitor C401 on the output side of coil L400. The voltage VL_IN and the voltage VL_OUT have a relationship of VL_IN>VL_OUT.

In FIG. 2, the battery VBATT, the voltage VL_IN of the capacitor C400, and the voltage VL_OUT of the capacitor C401 are all, for example, 12 [V] in normal times. Here, consider a case where pulse-like noise VNOISE is superimposed on the normal voltage value of battery VBATT. Due to the noise VNOISE, the voltage value of the battery VBATT rapidly increases to the voltage value V11. Due to this voltage increase, the voltage VL_IN stored in capacitor C400 also increases. The current/voltage monitoring circuit U310 monitors the rise in voltage VL_IN by comparing it with a predetermined threshold value. Current/voltage monitoring circuit U310 turns off switch element Q303 when voltage VL_IN exceeds a threshold value.

In this example, the current/voltage monitoring circuit U310 detects the voltage increase before the voltage VL_IN rises to the voltage value V12 indicated by the broken line, and turns off the switch element Q303. That is, when the voltage rises and exceeds the threshold (for example, 18 [V]) detected by the current-voltage monitoring circuit U310, the current-voltage monitoring circuit U310 turns off the switch element Q303. In this example, current/voltage monitoring circuit U310 turns off switch element Q303 at time t1.

When switch element Q303 is turned off, voltage VL_IN begins to fall. Even when switch element Q303 is turned off, current flow is maintained by coil L400. That is, the electrical energy stored in the coil L400 is released, and a current flows toward the capacitor C401 and a subsequent circuit (not shown). Capacitor C401 is charged by a current due to electrical energy released from coil L400. As a result, the voltage VL_OUT stored in the capacitor C401 increases. Therefore, the voltage VL_OUT rises to the voltage value V13. Thereafter, the voltage VL_OUT drops due to leakage to subsequent devices. When the switch element Q303 is turned on at time t2, the voltage VL_OUT rises, then falls and returns to the normal voltage value (for example, 12 [V]). Note that when the switch element Q303 is turned off, the connection between the subsequent device and the unit U400 is cut off by the aforementioned relay or the like. This charges the capacitor C401.

Here, the capacitance of the capacitor C401, which is part of the π-type filter, may not be able to be increased from the viewpoint of realizing a predetermined cutoff frequency. The voltage value V13 is a large value (for example, about 30 [V]) that significantly exceeds the threshold detected by the current/voltage monitoring circuit U310. If the capacitance of the capacitor C401 is small, there is a possibility that the withstand voltage of the circuit will be exceeded. It is necessary to avoid situations where the voltage exceeds the withstand voltage of the ECU's internal circuits. Even if the capacitance of the capacitor C401 is small, such a problem can be solved by the power supply control circuit of the embodiment described below.

(First embodiment)
First, the configuration of the power supply control circuit according to the first embodiment will be described. FIG. 3 is a diagram showing the configuration of the power supply control circuit of the first embodiment. The power supply control circuit 1a shown in FIG. 3 differs from the power supply control circuit 1 of the comparative example shown in FIG. 1 in that diodes D410 and D411 are added. Diodes D410 and D411 are connected such that the cathodes face the front side of the coil L400 and the anodes face the rear side of the coil L400.

When current/voltage monitoring circuit U310 detects overcurrent or overvoltage due to noise VNOISE and switch element Q303 is turned off, a free circulation is formed by coil L400 and diodes D410 and D411. In other words, a bypass circuit is formed in which the current flowing from the coil L400 is returned to the input side. A return current path IC2 flowing through the bypass circuit is a path from one end side (node N1 side) of the coil L400, passing through a diode D410 and a diode D411, and returning to the other end side (node N2 side) of the coil L400. If voltage VL_IN<voltage VL_0UT, the electric energy stored in coil L400 can be released by circulation through path IC2. By discharging the electrical energy stored in the coil L400, it is possible to suppress the voltage increase in the capacitor C401. That is, in this embodiment, in order to avoid exceeding the withstand voltage of the internal circuit of the ECU, the voltage on the input side of the coil L400 and the voltage on the output side of the coil L400 are compared, and the output voltage is higher. In this case, the charge can be released to the input side by the above-mentioned reflux.

By the way, forward voltage exists in each of the diodes D410 and D411. These diodes D410 and D411 are connected in series, and the sum of their forward voltages is the offset voltage V0FFSET. Considering this offset voltage V0FFSET,
Voltage VL_IN + offset voltage V0FFSET < voltage VL_0UT
When , the above-mentioned reflux of route IC2 occurs. As a result, even if the capacitance of the capacitor C401 on the output side of the coil L400 is small, it is possible to avoid a situation in which the withstand voltage of the circuit is exceeded even when noise VNOISE occurs, as in the case of the comparative example.

In this embodiment, two diodes D410 and D411 connected in series are used. During normal operation when no noise is applied, diodes D410 and D411 do not operate because the voltage on the cathode side of diodes D410 and D411 is high. When noise VNOISE occurs, freewheeling flows through path IC2 when the difference between the voltage of capacitor C400 and the voltage of capacitor C401 exceeds the sum of the forward voltages of diodes D410 and D411. The electric energy stored in coil L400 can be released by this return flow through path IC2. In other words, even if the two diodes D410 and D411 are provided, normal operation is not affected, and when noise VNOISE occurs, it is possible to avoid a situation where the withstand voltage of the circuit is exceeded.

In this example, two stages of forward voltage are provided by two diodes D410 and D411. If the forward voltage of one diode is Vf, the forward voltage of the two stages will be twice (that is, Vf×2). By providing a plurality of diodes, it is possible to prevent the diodes from turning on when there is some voltage fluctuation. The number of diodes connected is not limited to two stages. The number of connected diodes may be increased to three stages (that is, Vf x 3), or the number of connected diodes may be reduced to one stage (that is, Vf x 1). In this way, when the diodes are connected in series, the sum of the forward voltages Vf becomes the above offset voltage V0FFSET. When a plurality of diodes with the same forward voltage are connected, the offset voltage V0FFSET is a multiple of the forward voltage Vf corresponding to the number of connections. When the difference between the voltage of capacitor C400 and the voltage of capacitor C401 exceeds the sum of the forward voltages of diodes D410 and D411, freewheeling in path IC2 flows.

Note that instead of the diode, it is also possible to provide a semiconductor element including a diode, such as an FET or an IGBT (Insulated Gate Bipolar Transistor). Even when FETs and IGBTs are used, the same effect as when using diodes can be obtained. However, it is preferable to use a diode as shown in FIG. 3 because the structure is inexpensive and simple.

Next, the operation will be explained. FIG. 4 is a waveform diagram illustrating the operation of the power supply control circuit 1a of the first embodiment. In FIG. 4, the horizontal axis is time and the vertical axis is voltage.

In FIG. 4, consider the case where pulse-like noise VNOISE is superimposed on the normal voltage value of battery VBATT, as in the case of FIG. Due to the noise VNOISE, the voltage value of the battery VBATT rapidly increases to the voltage value V21. Due to this voltage increase, the voltage VL_IN stored in capacitor C400 also increases. The current/voltage monitoring circuit U310 monitors the rise in voltage VL_IN by comparing it with a predetermined threshold value. Current/voltage monitoring circuit U310 turns off switch element Q303 when voltage VL_IN exceeds a threshold value.

In this example, the current/voltage monitoring circuit U310 detects a rise in voltage before the voltage VL_IN rises to the voltage value V22 shown by the broken line, and turns off the switch element Q303. In this example, current/voltage monitoring circuit U310 turns off switch element Q303 at time t1'.

When switching element Q303 is turned off, the electrical energy stored in coil L400 is released. At this time, the electric energy accumulated in the coil L400 can be released by generating the above-mentioned reflux in the path IC2. By discharging the electrical energy stored in the coil L400, it is possible to suppress the voltage increase in the capacitor C401. In this example, voltage VL_OUT rises to voltage value V23. The voltage value V23 slightly exceeds the threshold value (for example, 18 [V]) of the current/voltage monitoring circuit U310. After that, voltage VL_OUT falls. When the switch element Q303 is turned on at time t2', the voltage VL_OUT rises, then falls and returns to the normal voltage value (for example, 12 [V]). That is, when all the electrical energy stored in the coil L400 is released, the series of operations stops, and the voltage VL_IN and the voltage VL_OUT return to their normal voltage values.

As described above, since electric energy can be released through reflux, even if strong noise is applied, it can be controlled so that the withstand voltage of the ECU's internal circuit is not exceeded, without increasing the capacitance of the capacitor. Therefore, it is possible to use a capacitor with a small capacity, so it is possible to take measures against vibration, suppress the increase in size of the device, reduce weight, improve fuel efficiency, and reduce costs.

(Second embodiment)
FIG. 5 is a diagram showing the configuration of the power supply control circuit 1b of the second embodiment. The power supply control circuit 1b shown in FIG. 5 differs from the power supply control circuit 1a shown in FIG. 3 in the configuration of the unit U400a. In unit U400a, common mode choke coil L401 is used instead of coil L400 of unit U400. Furthermore, unit U400a includes diodes D401 and D402. Common mode choke coil L401 includes two windings. Winding L4 on one side of common mode choke coil L401 acts as coil L400 in FIG. 3.

The diode D401 and the diode D402 are connected in opposite directions. That is, the cathode of the diode D401 and the anode of the diode D402 are connected, and the anode of the diode D401 and the cathode of the diode D402 are connected. Therefore, when the potential of the ground line GND1 on the previous stage side of these diodes D401 and D402, that is, on the side closer to the unit U100, becomes high and exceeds the forward voltage Vf of the diode D401, the diode D401 is turned on.

On the contrary, when the potential of the ground line GND2 downstream of these diodes D401 and D402 becomes higher and exceeds the forward voltage Vf of the diode D402, the diode D402 turns on. Therefore, the potential difference between the ground lines between the front side and the rear side of these diodes D401 and D402 can be kept below the forward voltage Vf. Note that the forward voltage Vf is, for example, 0.4 [V].

According to the power supply control circuit of the second embodiment shown in FIG. 5, when noise is generated by the winding L4 on one side of the common mode choke coil L401 and turns off the switch element Q303, as in the first embodiment, Even if there is, it can be controlled so that the withstand voltage of the ECU's internal circuit is not exceeded. At the same time, common mode noise can be reduced by the common mode choke coil L401.

1, 1a, 1b Power supply control circuit C200, C201, C400, C401 Capacitor D200, D201, D400,
D401, D402, D410, D411 Diode GND, GND1, GND2 Ground wire L100, L400 Coil L401 Common mode choke coil Q303 Switch element R320 Resistor U100, U200, U300, U400, U400a Unit U310 Current voltage monitoring circuit

Claims

An input terminal to which a DC power supply can be connected,
a power supply line that supplies power from the input terminal to a subsequent circuit;
a coil provided on the power line;
a first capacitor connected between the input terminal side of the coil and a ground line for the power line;
a second capacitor connected between the circuit side of the latter stage of the coil and the ground line;
a switch element connected in series to the power supply line to turn on or off power supply to a subsequent circuit;
a monitoring circuit that turns off the switch element when the voltage or current of the power supply line exceeds a threshold;
a semiconductor element including a diode connected in parallel with the coil such that the cathode faces the front side of the coil and the anode faces the rear side of the coil;
Power control circuit including.
2. The power supply control circuit according to claim 1, wherein the semiconductor element is turned on when a difference between the voltage of the first capacitor and the voltage of the second capacitor exceeds a forward voltage of the diode.
including a plurality of the diodes,
the plurality of diodes are connected in series,
3. The power supply control circuit according to claim 2, wherein the semiconductor element is turned on when the difference exceeds a sum of forward voltages of the diodes connected in series.