CN115220510B - Constant-voltage current-limiting driving circuit, electronic control unit and vehicle - Google Patents

Constant-voltage current-limiting driving circuit, electronic control unit and vehicle Download PDF

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Publication number
CN115220510B
CN115220510B CN202111487873.6A CN202111487873A CN115220510B CN 115220510 B CN115220510 B CN 115220510B CN 202111487873 A CN202111487873 A CN 202111487873A CN 115220510 B CN115220510 B CN 115220510B
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resistor
circuit
triode
constant voltage
capacitor
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CN115220510A (en
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伍世儒
梁志伟
李尚司
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Guangzhou Automobile Group Co Ltd
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Guangzhou Automobile Group Co Ltd
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    • G—PHYSICS
    • G05—CONTROLLING; REGULATING
    • G05F—SYSTEMS FOR REGULATING ELECTRIC OR MAGNETIC VARIABLES
    • G05F1/00—Automatic systems in which deviations of an electric quantity from one or more predetermined values are detected at the output of the system and fed back to a device within the system to restore the detected quantity to its predetermined value or values, i.e. retroactive systems
    • G05F1/10—Regulating voltage or current
    • G05F1/46—Regulating voltage or current wherein the variable actually regulated by the final control device is dc
    • G05F1/56—Regulating voltage or current wherein the variable actually regulated by the final control device is dc using semiconductor devices in series with the load as final control devices
    • G05F1/561—Voltage to current converters
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60R—VEHICLES, VEHICLE FITTINGS, OR VEHICLE PARTS, NOT OTHERWISE PROVIDED FOR
    • B60R16/00—Electric or fluid circuits specially adapted for vehicles and not otherwise provided for; Arrangement of elements of electric or fluid circuits specially adapted for vehicles and not otherwise provided for
    • B60R16/02—Electric or fluid circuits specially adapted for vehicles and not otherwise provided for; Arrangement of elements of electric or fluid circuits specially adapted for vehicles and not otherwise provided for electric constitutive elements
    • B60R16/023—Electric or fluid circuits specially adapted for vehicles and not otherwise provided for; Arrangement of elements of electric or fluid circuits specially adapted for vehicles and not otherwise provided for electric constitutive elements for transmission of signals between vehicle parts or subsystems
    • B60R16/0231—Circuits relating to the driving or the functioning of the vehicle
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H9/00—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection
    • H02H9/02—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection responsive to excess current
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
    • Y02B20/00—Energy efficient lighting technologies, e.g. halogen lamps or gas discharge lamps
    • Y02B20/30—Semiconductor lamps, e.g. solid state lamps [SSL] light emitting diodes [LED] or organic LED [OLED]

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  • Engineering & Computer Science (AREA)
  • Automation & Control Theory (AREA)
  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • General Physics & Mathematics (AREA)
  • Radar, Positioning & Navigation (AREA)
  • Power Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Continuous-Control Power Sources That Use Transistors (AREA)

Abstract

The invention discloses a constant voltage current-limiting driving circuit, an electronic control unit and a vehicle, comprising: an input enabling circuit connected with an external power supply, a control signal input source, a current limiting circuit and a constant voltage circuit and used for amplifying the input control signal and controlling the opening and closing of the constant voltage current limiting driving circuit; the current limiting circuit is connected with the input enabling circuit and the constant voltage circuit and is used for controlling the output current of the constant voltage current limiting driving circuit for generating short circuit to not exceed a preset limiting value; the constant voltage circuit is connected with the input enabling circuit, the current limiting circuit and the protection circuit and is used for controlling the output voltage of the constant voltage current limiting driving circuit to be constant; and the protection circuit is connected with the output end and the constant voltage circuit and is used for electrostatic protection of the constant voltage current-limiting driving circuit. The constant-voltage current-limiting driving circuit provided by the invention has the advantages that the constant-voltage driving function is carried out on the internal load and the external load of the ECU, the current-limiting measures are automatically taken when the load has a short-circuit fault, the load is prevented from being further damaged, and other functions are prevented from being influenced.

Description

Constant-voltage current-limiting driving circuit, electronic control unit and vehicle
Technical Field
The invention relates to the technical field of automobile electronic circuits, in particular to a constant-voltage current-limiting driving circuit, an electronic control unit and a vehicle.
Background
On an automotive Electronic Control Unit (ECU), a driving circuit is required to drive a load, including driving an internal load to the ECU and an external load to the ECU. In order to protect electronic components in the ECU, a constant voltage current limiting driving circuit is generally used as the driving circuit.
At present, a constant voltage current limiting driving circuit used by an ECU generally uses an Integrated Circuit (IC) directly, but the IC has the following problems:
1. the cost is high, and many performance parameters are fixed inside the IC and cannot be changed.
2. The driving output part circuit of the IC is low in withstand voltage and is easily damaged.
3. The power input part has poor voltage resistance and stability and is easy to burn.
4. Once the IC is burnt out and damaged, the IC can only be directly scrapped, a new IC is replaced, and the maintenance cost is increased.
Disclosure of Invention
The purpose of the invention is that: the constant-voltage current-limiting driving circuit has an enabling function, can be used for constant-voltage driving of an ECU internal load and an external load, automatically takes current-limiting measures when a short-circuit fault occurs to the load, and avoids further damage to the load and influences other functions.
In order to achieve the above object, the present invention provides a constant voltage current limiting driving circuit comprising: an input enable circuit, a current limiting circuit, a constant voltage circuit and a protection circuit;
the input enabling circuit is connected with an external power supply, a control signal input source, the current limiting circuit and the constant voltage circuit and used for amplifying an input control signal and controlling the constant voltage current limiting driving circuit to be turned on and off;
the current limiting circuit is connected with the input enabling circuit and the constant voltage circuit and is used for controlling the output current of the constant voltage current limiting driving circuit, which is short-circuited, not to exceed a preset limiting value;
the constant voltage circuit is connected with the input enabling circuit, the current limiting circuit and the protection circuit and is used for controlling the output voltage of the constant voltage current limiting driving circuit to be constant;
the protection circuit is connected with the output end of the constant voltage current-limiting driving circuit and the constant voltage circuit and is used for electrostatic protection of the constant voltage current-limiting driving circuit.
Preferably, the input enabling circuit includes: the first capacitor, the third resistor, the third triode, the sixth resistor, the seventh resistor and the fifth capacitor;
the first capacitor is connected with the third resistor in parallel;
one end of the third resistor is connected with an external power supply, and the other end of the third resistor is connected with the collector electrode of the third triode;
the base electrode of the third triode is connected with the sixth resistor, the seventh resistor and the fifth capacitor, the collector electrode of the third triode is connected with the first capacitor, the third resistor and the current limiting circuit, and the emitter electrode of the third triode is connected with the constant voltage circuit;
one end of the sixth resistor is connected with a control signal input source, and the other end of the sixth resistor is connected with the seventh resistor, the fifth capacitor and the base electrode of the third triode;
the fifth capacitor is connected with the seventh resistor in parallel;
one end of the seventh resistor is connected with the sixth resistor and the base electrode of the third triode, and the other end of the seventh resistor is grounded.
Preferably, the third triode is an NPN triode.
Preferably, the current limiting circuit includes: the first resistor, the second resistor, the fourth resistor, the first triode and the second triode;
one end of the first resistor is connected with the second resistor, and the other end of the first resistor is connected with the emitter of the second triode;
one end of the second resistor is connected with the first resistor, and the other end of the second resistor is connected with the fourth resistor and the emitter of the first triode;
one end of the fourth resistor is connected with the second resistor and the emitter of the first triode, and the other end of the fourth resistor is connected with the base electrode of the second triode;
the base electrode of the first triode is connected with the collector electrode of the second triode and the input enabling circuit, the collector electrode of the first triode is connected with the constant voltage circuit, and the emitter electrode of the first triode is connected with the second resistor and the fourth resistor;
the base of the second triode is connected with the fourth resistor, the collector of the second triode is connected with the base of the first triode and the input enabling circuit, and the emitter of the second triode is connected with the first resistor.
Preferably, the first triode and the second triode are PNP type triodes.
Preferably, the constant voltage circuit includes: a ninth resistor, a tenth resistor, a fourth triode, a fifth resistor, an eighth resistor and a second capacitor;
the ninth resistor is connected with the tenth resistor in parallel;
one end of the tenth resistor is connected with the emitter of the fourth triode and the input enabling circuit, and the other end of the tenth resistor is grounded;
the base electrode of the fourth triode is connected with the fifth resistor, the eighth resistor, the second capacitor and the protection circuit, the collector electrode of the fourth triode is connected with the fifth resistor, the second capacitor and the current limiting circuit, and the emitter electrode of the fourth triode is connected with the ninth resistor, the tenth resistor and the input enabling circuit;
one end of the fifth resistor is connected with the collector electrode of the fourth triode, the current limiting circuit, the second capacitor and the protection circuit, and the other end of the fifth resistor is connected with the base electrode of the fourth triode, the eighth resistor and the second capacitor;
the second capacitor is connected in parallel with the fifth resistor.
Preferably, the fourth triode is an NPN triode.
Preferably, the protection circuit includes: a third capacitor and a fourth capacitor;
one end of the third capacitor is connected with the output ends of the fourth capacitor, the constant voltage circuit and the constant voltage current-limiting driving circuit, and the other end of the third capacitor is grounded;
the fourth capacitor is connected in parallel with the third capacitor.
The invention also provides an electronic control unit comprising a constant voltage current limiting drive circuit as defined in any one of the above.
The invention also provides a vehicle which comprises the vehicle body and the electronic control unit.
Compared with the prior art, the constant current limiting driving circuit provided by the invention has the following beneficial effects:
1. the constant voltage current limiting circuit provided by the embodiment of the invention automatically takes the current limiting measures when the load has a short circuit fault by performing a constant voltage driving function on the internal load and the external load of the ECU, so that the load is prevented from being further damaged and other functions are prevented from being influenced.
2. The constant voltage current limiting circuit provided by the embodiment of the invention also has an enabling function, and can be enabled and disabled as an operation IC. In addition, many of the problems of using ICs for driving are well addressed.
3. The constant voltage current limiting circuit provided by the embodiment of the invention is built by using discrete components, has low cost and meets the requirement of reducing the cost. Parameters such as driving voltage, current limiting value and the like can be conveniently adjusted by replacing passive components according to actual project requirements.
4. The drive output part of the constant voltage current limiting circuit provided by the embodiment of the invention uses the triode, has very high voltage withstand characteristic, is not easy to be damaged by overvoltage and static electricity, and can be directly used for driving an external load of the ECU. The power input part also uses a triode, and can well cope with abnormal voltage driven from VBAT. Even if the circuit fails, the failed components in the circuit can be easily found and replaced, and the maintenance cost is low.
Drawings
FIG. 1 is a schematic diagram of a constant voltage current limiting driving circuit according to an embodiment of the present invention;
FIG. 2 is a simplified schematic diagram of a constant voltage current limiting driving circuit according to an embodiment of the present invention when the load impedance is smaller than the load impedance threshold;
FIG. 3 is a schematic diagram of a current output curve of the constant voltage current-limiting driving circuit when the load impedance is smaller than a threshold value according to an embodiment of the present invention;
FIG. 4 is a schematic diagram of a constant voltage current limiting driving circuit according to an embodiment of the present invention, wherein the output voltage varies with the load impedance;
FIG. 5 is a schematic diagram showing the output current of the constant voltage circuit according to the embodiment of the present invention along with the load impedance;
fig. 6 is a schematic diagram showing an effect of the ninth resistor R9 and the tenth resistor R10 on the output constant voltage according to the embodiment of the present invention.
Detailed Description
The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
It should be understood that the step numbers used herein are for convenience of description only and are not limiting as to the order in which the steps are performed.
It is to be understood that the terminology used in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used in this specification and the appended claims, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise.
The terms "comprises" and "comprising" indicate the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.
The term "and/or" refers to any and all possible combinations of one or more of the associated listed items, and includes such combinations.
Referring to fig. 1, an embodiment of the present invention provides a constant voltage current limiting driving circuit 10, comprising: an input enable circuit 11, a current limiting circuit 12, a constant voltage circuit 13, and a protection circuit 14;
the input enabling circuit 11 is connected with an external power supply, a control signal input source, the current limiting circuit 12 and the constant voltage circuit 13, and is used for amplifying an input control signal and controlling the constant voltage current limiting driving circuit to be turned on and off;
the current limiting circuit 12 is connected with the input enabling circuit 11 and the constant voltage circuit 13, and is used for controlling the output current of the constant voltage current limiting driving circuit 10 for short circuit not to exceed a preset limiting value;
the constant voltage circuit 13 is connected with the input enabling circuit 11, the current limiting circuit 12 and the protection circuit 14 and is used for controlling the output voltage of the constant voltage current limiting driving circuit 10 to be constant;
the protection circuit 14 is connected to the output end of the constant voltage current-limiting driving circuit 10 and the constant voltage circuit 13, and is used for protecting the constant voltage current-limiting driving circuit 10 from static electricity.
It should be noted that, the INPUT signal in fig. 1 controls the on and off of the output of the constant voltage current limiting driving circuit. When the INPUT signal is at a high level, the output of the constant voltage current-limiting driving circuit is started.
The OUTPUT end is connected with a load to be powered, the working voltage required by the working condition of the load is the OUTPUT constant voltage of the constant voltage current-limiting driving circuit, and the working current is smaller than the maximum load current of the constant voltage current-limiting driving circuit. Moreover, if the load is sensitive to voltage ripple, a corresponding filter circuit needs to be added after OUTPUT.
U bat The voltage of the storage battery is input through the front-end power supply protection and filtering circuit, and the voltage range can be set according to actual requirements.
Specifically, the working principle of the constant voltage current-limiting driving circuit provided by the invention is as follows:
1. when the load impedance connected with the OUTPUT end is larger than the critical value, the circuit OUTPUT at the moment is constant voltage OUTPUT, and the working principle is as follows:
because the load impedance connected with the OUTPUT end is larger than the critical value, when the OUTPUT voltage passes through the voltage dividing circuit formed by the fifth resistor R5 and the eighth resistor R8, the base voltage is larger for the fourth triode Q4, so that the fourth triode Q4 is in an on state, and the fourth triode Q4, the fifth resistor R5 and the eighth resistor R8 form a negative feedback circuit. At this time, part of the output current is split from the branch where the collector of the fourth transistor Q4 is located, thereby reducing the output voltage. The reduction of the output voltage leads to the reduction of the base voltage provided by the voltage dividing circuit of the fifth resistor R5 and the eighth resistor R8 for the fourth triode Q4, and reduces the opening degree of the fourth triode Q4, thereby reducing the shunt of the branch where the collector of the fourth triode Q4 is located. When the equilibrium state is reached, a constant output voltage can be obtained.
The device parameters influencing the output constant voltage are calculated as follows:
first, since the emitters of the third transistor Q3 and the fourth transistor Q4 are connected together, and the third transistor Q3 and the fourth transistor Q4 are NPN transistors of the same model, it is possible to obtain:
U E－Q4 ＝U E－Q3 。
U BE－Q3 ＝U BE－Q4 。
secondly, according to the characteristics of the NPN triode, the following steps are obtained:
U B－Q3 ＝U E－Q3 +U BE－Q3 。
U B－Q4 ＝U E－Q4 +U BE－Q4 。
next, the circuit connection relationship according to fig. 1 can be obtained:
U B－Q3 ＝U in ＊R7/(R6+R7)。
U B－Q3 ＝U out ＊R8/(R5+R8)。
finally, the sum up can be obtained:
U out ＝U in ＊R7/(R6+R7)＊(R5+R8)/R8。
it should be noted that, the parameters in the above formula are defined as follows: u (U) in A voltage representing the INPUT; u (U) B－Q3 Representing the base voltage of the third transistor Q3; u (U) E－Q3 An emitter voltage of the third transistor Q3; u (U) BE－Q3 Representing the turn-on voltage of the third transistor Q3; u (U) B－Q4 Representing the base voltage of the fourth transistor Q4; u (U) E－Q4 An emitter voltage of the fourth transistor Q4; u (U) BE－Q4 Indicating the turn-on voltage of the fourth transistor Q4; u (U) out Representing the output voltage of the constant voltage current limiting drive circuit.
From the above analysis, it can be seen that the output voltage of the constant voltage current limiting circuit of the present invention is related to the INPUT voltage of the INPUT and the resistance values of the fifth resistor R5, the sixth resistor R6, the seventh resistor R7, and the eighth resistor R8.
2. When the connected load impedance is smaller than the critical value, the circuit output at this time is a constant current output circuit (limiting current output):
because the load impedance connected to the OUTPUT terminal is smaller than the threshold, the OUTPUT voltage passes through the R5 and R8 voltage dividing circuits, and the base voltage provided to the fourth transistor Q4 is smaller. The fourth transistor Q4 is turned off, and at this time, the first resistor R1, the second resistor R2, and the fourth resistor R4 form a current limiting circuit with the first transistor Q1 and the second transistor Q2, and since the fourth transistor Q4 is turned off, the circuit of fig. 1 can be simplified to a case without the fourth transistor Q4, as shown in fig. 2.
The device parameters affecting the constant current are specifically calculated as follows:
according to the connection relation that the first resistor R1, the second resistor R2 and the fourth resistor R4 form a current limiting circuit with the first triode Q1 and the second triode Q2, the following can be obtained:
I max ＝U BE－Q2 /(R1+R2)。
in U BE－Q2 Representing the turn-on voltage of the second transistor Q2.
From the above analysis, it can be seen that the output current of the constant voltage current limiting circuit of the present invention is related to the resistance values of the resistors R1 and R2.
The load critical impedance in the invention has the following working characteristics:
1. when the load impedance is smaller than the critical value, the output of the current-limiting driving circuit of the invention Fang Hengya is constant current and is Imax. By ohm's law u=ir, the output voltage increases linearly with increasing load impedance.
2. When the load impedance is equal to the critical value, the output voltage of the constant voltage current-limiting driving circuit of the invention is increased to the maximum U out At this time, there are:
U out ＝I max ＊R o
3. when the load impedance is larger than the critical value, the output constant voltage output of the constant voltage current-limiting driving circuit is U out . By ohm's law i=u/R, the output load current decreases as the load impedance increases. The output load current reaches a maximum at the load impedance threshold.
In one embodiment, the input enabling circuit 11 includes: the first capacitor C1, the third resistor R3, the third triode Q3, the sixth resistor R6, the seventh resistor R7 and the fifth capacitor C5;
the first capacitor C1 is connected with the third resistor R3 in parallel;
one end of the third resistor R3 is connected with an external power supply, and the other end of the third resistor R3 is connected with the collector electrode of the third triode Q3;
the base electrode of the third triode Q3 is connected with the sixth resistor R6, the seventh resistor R7 and the fifth capacitor C5, the collector electrode of the third triode Q3 is connected with the first capacitor C1, the third resistor R3 and the current limiting circuit 12, and the emitter electrode of the third triode Q3 is connected with the constant voltage circuit 13;
one end of the sixth resistor R6 is connected with a control signal input source, and the other end of the sixth resistor R6 is connected with the seventh resistor R7, the fifth capacitor C5 and the base electrode of the third triode Q3;
the fifth capacitor C5 is connected with the seventh resistor R7 in parallel;
one end of the seventh resistor R7 is connected with the sixth resistor R6 and the base electrode of the third triode Q3, and the other end of the seventh resistor R7 is grounded.
Specifically, as shown in fig. 1, the INPUT enabling circuit of the present invention is composed of a third triode Q3, a third resistor R3, a sixth resistor R6, a seventh resistor R7, a first capacitor C1 and a fifth capacitor C5, the circuit is enabled by the high and low level of the INPUT signal, when the INPUT signal is at the low level, the third triode Q3 is turned off, and the voltages across the third resistor R3 are both U bat The first transistor Q1 is turned off and no current is OUTPUT to the OUTPUT signal. The energy on the OUTPUT signal line is discharged to the ground through the fifth resistor R5 and the eighth resistor R8, and the circuit has no OUTPUT voltage.
When the INPUT signal is at a high level, the sixth resistor R6 is connected in series with the third triode Q3, and the seventh resistor R7 is connected in parallel with the third triode Q3, so as to ensure that the voltage between the BE poles is the starting voltage when the third triode Q3 is turned on, and the third triode Q3 is not damaged. The fifth capacitor C5 also functions as a filter capacitor. After the third triode Q3 is turned on, current appears at two ends of the third resistor R3, and a voltage difference exists, so that the first triode Q1 is turned on, and the whole circuit starts to work.
In one embodiment, the third transistor Q3 is an NPN transistor.
In one embodiment, the current limiting circuit 12 includes: the first resistor R1, the second resistor R2, the fourth resistor R4, the first triode Q1 and the second triode Q2;
one end of the first resistor R1 is connected with the second resistor R2, and the other end of the first resistor R1 is connected with the emitter of the second triode Q2;
one end of the second resistor R2 is connected with the first resistor R1, and the other end of the second resistor R2 is connected with the fourth resistor R4 and the emitter of the first triode Q1;
one end of the fourth resistor R4 is connected with the second resistor R2 and the emitter of the first triode Q1, and the other end of the fourth resistor R4 is connected with the base electrode of the second triode Q2;
the base electrode of the first triode Q1 is connected with the collector electrode of the second triode Q2 and the input enabling circuit 11, the collector electrode of the first triode Q1 is connected with the constant voltage circuit 13, and the emitter electrode of the first triode Q1 is connected with the second resistor R2 and the fourth resistor R4;
the base of the second triode Q2 is connected with the fourth resistor R4, the collector of the second triode Q2 is connected with the base of the first triode Q1 and the input enabling circuit 11, and the emitter of the second triode Q2 is connected with the first resistor R1.
In one embodiment, the first transistor Q1 and the second transistor Q2 are PNP transistors.
In one embodiment, the constant voltage circuit 13 includes: a ninth resistor R9, a tenth resistor R10, a fourth triode Q4, a fifth resistor R5, an eighth resistor R8 and a second capacitor C2;
the ninth resistor R9 is connected with the tenth resistor R10 in parallel;
one end of the tenth resistor R10 is connected to the emitter of the fourth triode Q4 and the input enabling circuit 11, and the other end is grounded;
the base electrode of the fourth triode Q4 is connected with the fifth resistor R5, the eighth resistor R8, the second capacitor C2 and the protection circuit 14, the collector electrode of the fourth triode Q4 is connected with the fifth resistor R5, the second capacitor C2 and the current limiting circuit 12, and the emitter electrode of the fourth triode Q4 is connected with the ninth resistor R9, the tenth resistor R10 and the input enabling circuit 11;
one end of the fifth resistor R5 is connected to the collector of the fourth triode Q4, the current limiting circuit 12, the second capacitor C2 and the protection circuit 14, and the other end is connected to the base of the fourth triode Q4, the eighth resistor R8 and the second capacitor C2;
the second capacitor C2 is connected in parallel with the fifth resistor R5.
In the constant voltage circuit 13, the ninth resistor R9 and the tenth resistor R10 are used for performing voltage division and current limiting protection on the fourth triode Q4, and when the output interface of the constant voltage current limiting driving circuit 10 performs an electrical short circuit test, the ninth resistor R9 and the tenth resistor R10 perform voltage division to avoid breakdown damage to the collector and the emitter of the fourth triode Q4.
In one embodiment, the fourth transistor Q4 is an NPN transistor.
In one embodiment, the protection circuit 14 includes: a third capacitor C3 and a fourth capacitor C4;
one end of the third capacitor C3 is connected to the fourth capacitor C4, the constant voltage circuit 13 and the output end of the constant voltage current-limiting driving circuit 10, and the other end is grounded;
the fourth capacitor C4 and the third capacitor C3 are connected in parallel.
Specifically, the protection circuit 14 of the present invention is composed of the third capacitor C3 and the fourth capacitor C4, mainly preventing external electrostatic interference, and may also perform ripple filtering on the output power supply. The actual capacitor has poles, so if the effect of filtering by using 1 capacitor is poor, inflection points can appear at the places of the poles, and frequencies higher than the poles can be shown as sensibility, thereby influencing the antistatic effect and circuit stability. Therefore, two capacitors with 100 times of phase difference are selected for parallel connection, the frequency phase difference of the two poles is larger, the respective poles can be avoided for complementation, and the current stability is improved.
Compared with the prior art, the constant-voltage current-limiting driving circuit provided by the invention has the following beneficial effects:
1. the constant voltage current limiting circuit provided by the embodiment of the invention automatically takes the current limiting measures when the load has a short circuit fault by performing a constant voltage driving function on the internal load and the external load of the ECU, so that the load is prevented from being further damaged and other functions are prevented from being influenced.
2. The constant voltage current limiting circuit provided by the embodiment of the invention also has an enabling function, and can be enabled and disabled as an operation IC. In addition, many of the problems of using ICs for driving are well addressed.
3. The constant voltage current limiting circuit provided by the embodiment of the invention is built by using discrete components, has low cost and meets the requirement of reducing the cost. Parameters such as driving voltage, current limiting value and the like can be conveniently adjusted by replacing passive components according to actual project requirements.
4. The drive output part of the constant voltage current limiting circuit provided by the embodiment of the invention uses the triode, has very high voltage withstand characteristic, is not easy to be damaged by overvoltage and static electricity, and can be directly used for driving an external load of the ECU. The power input part also uses a triode, and can well cope with abnormal voltage driven from VBAT. Even if the circuit fails, the failed components in the circuit can be easily found and replaced, and the maintenance cost is low.
In order to better illustrate the constant voltage current limiting circuit provided by the invention, the circuit shown in fig. 1 is subjected to simulation test.
Taking the example of 5V current limiting 20mA output by the constant voltage current limiting driving circuit for testing, the selected component parameters are shown in the table 1:
table 1 constant voltage current limiting driving circuit outputs 5V current limiting 20mA component parameter value
According to the parameters of the components, the critical value of the load impedance is 250 Ω, the simulation results are shown in fig. 3-6, fig. 3 is a current output curve of the constant voltage current limiting driving circuit when the load impedance is smaller than the critical value, and it can be seen from fig. 3 that the output current of the constant voltage current limiting driving circuit is constant when the load impedance is smaller than the critical value.
Fig. 4 is a graph showing the variation of the output voltage of the constant voltage current limiting driving circuit along with the load impedance, and as can be seen from fig. 4, the output voltage shows a growing trend along with the increase of the load impedance, when the load impedance is equal to the critical value, the output voltage increases to the maximum, and the subsequent output reaches the constant voltage state.
Fig. 5 is a graph showing the variation of the output current of the constant voltage current circuit with the load impedance, and as can be seen from fig. 6, the first half of the simulation result of fig. 5 shows that when the load impedance is smaller than the critical value, the output current of the constant voltage current-limiting driving circuit remains almost unchanged, and the output voltage corresponding to fig. 4 increases linearly with the load impedance.
According to the second half of the simulation result of fig. 4, when the load impedance is greater than the critical value, the output voltage of the constant voltage current-limiting driving circuit remains unchanged, and the output current corresponding to fig. 5 decreases with the load impedance.
As can be seen from the simulation results of fig. 4, when the load impedance is greater than the value according to the formula: u (U) out ＝I max When the load impedance critical value calculated by R theory is, the voltage output by the constant voltage current-limiting driving circuit is not instantaneously changed into constant voltage, and a transition period exists, when the constant voltage is actually output, the impedance ratio of the load is as follows: u (U) out ＝I max The value of the theoretical calculation of R is large. Therefore, in practical application, it is required thatIn the formula: u (U) out ＝I max And (3) on the basis of calculating the load impedance critical value, performing simulation debugging matching to determine the actual load impedance theoretical value.
Fig. 6 is a simulation result of the effect of the ninth resistor R9 and the tenth resistor R10 on the output constant voltage, and according to the simulation result of fig. 6, it can be obtained that when the ninth resistor R9 and the tenth resistor R10 are small, the effect on the output constant voltage is large, and the output constant voltage may fluctuate rapidly. When the total resistance of the ninth resistor R9 and the tenth resistor R10 connected in parallel is greater than 500 ohms, the influence thereof on the output constant voltage is small. According to project experience, the values of the ninth resistor R9 and the tenth resistor R10 are 1K.
The invention also provides an electronic control unit comprising a constant voltage current limiting drive circuit as defined in any one of the above.
The invention also provides a vehicle which comprises the vehicle body and the electronic control unit.
It should be noted that the above-described apparatus embodiments are merely illustrative, and the units described as separate units may or may not be physically separate, and units shown as units may or may not be physical units, may be located in one place, or may be distributed over a plurality of network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution of this embodiment. In addition, in the drawings of the embodiment of the device provided by the invention, the connection relation between the modules represents that the modules have communication connection, and can be specifically implemented as one or more communication buses or signal lines. Those of ordinary skill in the art will understand and implement the present invention without undue burden.
The foregoing is merely a preferred embodiment of the present invention, and it should be noted that modifications and substitutions can be made by those skilled in the art without departing from the technical principles of the present invention, and these modifications and substitutions should also be considered as being within the scope of the present invention.

Claims (9)

1. A constant voltage current-limiting driving circuit, characterized by comprising: an input enable circuit, a current limiting circuit, a constant voltage circuit and a protection circuit;
the input enabling circuit is connected with an external power supply, a control signal input source, the current limiting circuit and the constant voltage circuit and used for amplifying an input control signal and controlling the constant voltage current limiting driving circuit to be turned on and off;
the current limiting circuit is connected with the input enabling circuit and the constant voltage circuit and is used for controlling the output current of the constant voltage current limiting driving circuit, which is short-circuited, not to exceed a preset limiting value;
the constant voltage circuit is connected with the input enabling circuit, the current limiting circuit and the protection circuit and is used for controlling the output voltage of the constant voltage current limiting driving circuit to be constant;
the protection circuit is connected with the output end of the constant-voltage current-limiting driving circuit and the constant-voltage circuit and is used for electrostatic protection of the constant-voltage current-limiting driving circuit;
wherein the constant voltage circuit includes: a ninth resistor, a tenth resistor, a fourth triode, a fifth resistor, an eighth resistor and a second capacitor;
the ninth resistor is connected with the tenth resistor in parallel;
one end of the tenth resistor is connected with the emitter of the fourth triode and the input enabling circuit, and the other end of the tenth resistor is grounded;
the base electrode of the fourth triode is connected with the fifth resistor, the eighth resistor and the second capacitor, the collector electrode of the fourth triode is connected with the fifth resistor, the second capacitor, the protection circuit and the current limiting circuit, and the emitter electrode of the fourth triode is connected with the ninth resistor, the tenth resistor and the input enabling circuit;
one end of the fifth resistor is connected with the collector electrode of the fourth triode, the current limiting circuit, the second capacitor and the protection circuit, and the other end of the fifth resistor is connected with the base electrode of the fourth triode, one end of the eighth resistor and the second capacitor;
the other end of the eighth resistor is grounded, and the second capacitor is connected with the fifth resistor in parallel.
2. The constant voltage current-limiting driving circuit according to claim 1, wherein the input enabling circuit comprises: the first capacitor, the third resistor, the third triode, the sixth resistor, the seventh resistor and the fifth capacitor;
the first capacitor is connected with the third resistor in parallel;
one end of the third resistor is connected with an external power supply, and the other end of the third resistor is connected with the collector electrode of the third triode;
the base electrode of the third triode is connected with the sixth resistor, the seventh resistor and the fifth capacitor, the collector electrode of the third triode is connected with the first capacitor, the third resistor and the current limiting circuit, and the emitter electrode of the third triode is connected with the constant voltage circuit;
one end of the sixth resistor is connected with a control signal input source, and the other end of the sixth resistor is connected with the seventh resistor, the fifth capacitor and the base electrode of the third triode;
the fifth capacitor is connected with the seventh resistor in parallel;
one end of the seventh resistor is connected with the sixth resistor and the base electrode of the third triode, and the other end of the seventh resistor is grounded.
3. The constant voltage current-limiting driving circuit according to claim 2, wherein the third transistor is an NPN transistor.
4. The constant voltage current-limiting driving circuit according to claim 1, wherein the current-limiting circuit includes: the first resistor, the second resistor, the fourth resistor, the first triode and the second triode;
one end of the first resistor is connected with the second resistor, and the other end of the first resistor is connected with the emitter of the second triode;
one end of the second resistor is connected with the first resistor, and the other end of the second resistor is connected with the fourth resistor and the emitter of the first triode;
one end of the fourth resistor is connected with the second resistor and the emitter of the first triode, and the other end of the fourth resistor is connected with the base electrode of the second triode;
the base electrode of the first triode is connected with the collector electrode of the second triode and the input enabling circuit, the collector electrode of the first triode is connected with the constant voltage circuit, and the emitter electrode of the first triode is connected with the second resistor and the fourth resistor;
the base of the second triode is connected with the fourth resistor, the collector of the second triode is connected with the base of the first triode and the input enabling circuit, and the emitter of the second triode is connected with the first resistor.
5. The constant voltage current-limiting driving circuit according to claim 4, wherein the first transistor and the second transistor are PNP transistors.
6. The constant voltage current-limiting driving circuit according to claim 1, wherein the fourth transistor is an NPN transistor.
7. The constant voltage current-limiting driving circuit according to any one of claims 1 to 6, wherein the protection circuit includes: a third capacitor and a fourth capacitor;
one end of the third capacitor is connected with the output ends of the fourth capacitor, the constant voltage circuit and the constant voltage current-limiting driving circuit, and the other end of the third capacitor is grounded;
the fourth capacitor is connected in parallel with the third capacitor.
8. An electronic control unit comprising the constant voltage current limiting driving circuit according to any one of claims 1 to 7.
9. A vehicle, characterized in that it comprises a vehicle body and an electronic control unit according to claim 8.
CN202111487873.6A 2021-12-06 2021-12-06 Constant-voltage current-limiting driving circuit, electronic control unit and vehicle Active CN115220510B (en)

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Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH052226U (en) * 1991-06-17 1993-01-14 パイオニア株式会社 Current limiter circuit
CN103204115A (en) * 2012-01-12 2013-07-17 现代摩比斯株式会社 Apparatus for supplying power
CN203250233U (en) * 2013-06-03 2013-10-23 青岛海信宽带多媒体技术有限公司 Direct current voltage reduction circuit and electronic products
CN104167919A (en) * 2014-08-14 2014-11-26 深圳市创维群欣安防科技有限公司 Device for controlling flyback power source cross load output voltages
CN211123821U (en) * 2019-11-14 2020-07-28 青岛鼎信通讯股份有限公司 Linear voltage stabilizing circuit applied to ammeter and terminal

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH052226U (en) * 1991-06-17 1993-01-14 パイオニア株式会社 Current limiter circuit
CN103204115A (en) * 2012-01-12 2013-07-17 现代摩比斯株式会社 Apparatus for supplying power
CN203250233U (en) * 2013-06-03 2013-10-23 青岛海信宽带多媒体技术有限公司 Direct current voltage reduction circuit and electronic products
CN104167919A (en) * 2014-08-14 2014-11-26 深圳市创维群欣安防科技有限公司 Device for controlling flyback power source cross load output voltages
CN211123821U (en) * 2019-11-14 2020-07-28 青岛鼎信通讯股份有限公司 Linear voltage stabilizing circuit applied to ammeter and terminal

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