CN113690846A - Overvoltage protection circuit, vehicle-mounted terminal and commercial vehicle - Google Patents
Overvoltage protection circuit, vehicle-mounted terminal and commercial vehicle Download PDFInfo
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- CN113690846A CN113690846A CN202110798992.7A CN202110798992A CN113690846A CN 113690846 A CN113690846 A CN 113690846A CN 202110798992 A CN202110798992 A CN 202110798992A CN 113690846 A CN113690846 A CN 113690846A
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- 238000001514 detection method Methods 0.000 claims abstract description 29
- 230000003750 conditioning effect Effects 0.000 claims abstract description 23
- 239000003990 capacitor Substances 0.000 claims description 22
- 230000000087 stabilizing effect Effects 0.000 claims description 5
- 230000001934 delay Effects 0.000 claims 1
- 238000010586 diagram Methods 0.000 description 12
- 238000000034 method Methods 0.000 description 11
- 230000010355 oscillation Effects 0.000 description 6
- 238000004458 analytical method Methods 0.000 description 4
- 230000003321 amplification Effects 0.000 description 3
- 238000004519 manufacturing process Methods 0.000 description 3
- 238000003199 nucleic acid amplification method Methods 0.000 description 3
- 238000010521 absorption reaction Methods 0.000 description 2
- 230000001105 regulatory effect Effects 0.000 description 2
- 230000001052 transient effect Effects 0.000 description 2
- 230000001154 acute effect Effects 0.000 description 1
- 230000033228 biological regulation Effects 0.000 description 1
- 230000015556 catabolic process Effects 0.000 description 1
- 230000001276 controlling effect Effects 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 230000003111 delayed effect Effects 0.000 description 1
- 238000007599 discharging Methods 0.000 description 1
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H3/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection
- H02H3/20—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to excess voltage
- H02H3/202—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to excess voltage for dc systems
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- 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
- B60R16/03—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 supply of electrical power to vehicle subsystems or for
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- 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
- Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
- Y02T10/00—Road transport of goods or passengers
- Y02T10/80—Technologies aiming to reduce greenhouse gasses emissions common to all road transportation technologies
- Y02T10/92—Energy efficient charging or discharging systems for batteries, ultracapacitors, supercapacitors or double-layer capacitors specially adapted for vehicles
Abstract
The application provides an overvoltage protection circuit, a vehicle-mounted terminal and a commercial vehicle. Wherein overvoltage protection circuit for vehicle-mounted terminal power input port includes: a first end of the first switch tube is connected with the output end of the overvoltage protection circuit, and a second end of the first switch tube is connected with the input end of the overvoltage protection circuit; the voltage detection unit is used for detecting the voltage of the first end of the first switching tube; and the conditioning unit is used for adjusting the voltage of the control end of the first switch tube according to the voltage detection unit so that the voltage of the first end of the first switch tube is in a first preset range.
Description
Technical Field
The application belongs to the field of commercial vehicles, and particularly relates to an overvoltage protection circuit, a vehicle-mounted terminal and a commercial vehicle.
Background
At present, the working voltage range of the existing vehicle-mounted terminal is generally 9V-36V, and power is required to be supplied by a power supply system of a commercial vehicle. In operation, the existing commercial vehicle can generate relatively high energy and relatively frequent voltage impact at the power supply end. This problem is particularly acute with the relatively low performance of the power supply system of some commercial vehicles.
The conventional vehicle-mounted terminal is generally provided with a TVS diode or a piezoresistor and other protection devices at a power input end. The protection device can protect the vehicle-mounted terminal from being damaged when the electric shock occurs.
However, the protection measures are too simple and the protection strength is limited. For some vehicles with poor new performance of the power system, a high-energy voltage surge may be generated on the power line. The energy of this voltage surge can be high, particularly when striking a fire. When the impact occurs, it is difficult for the aforementioned protection measures to provide effective protection to the in-vehicle terminal.
Disclosure of Invention
Based on this, this application provides an overvoltage crowbar for vehicle mounted terminal power input port includes: a first end of the first switch tube is connected with the output end of the overvoltage protection circuit, and a second end of the first switch tube is connected with the input end of the overvoltage protection circuit; the voltage detection unit is used for detecting the voltage of the first end of the first switching tube; and the conditioning unit is used for adjusting the voltage of the control end of the first switch tube according to the voltage detection unit so that the voltage of the first end of the first switch tube is in a first preset range.
Alternatively, the voltage detection unit may include: a first zener diode and a first resistor connected in series, wherein the first zener diode is connected to a first end of the first switching tube; the first resistor is grounded.
Optionally, the voltage detection unit may further include: and the control end of the second switching tube is connected with the first voltage stabilizing diode and the first resistor, and the first end of the second switching tube is connected with the conditioning unit.
Optionally, the voltage detection unit may further include: the second resistor is connected between the second end of the second switch tube and the ground; and the third resistor is connected between the second end of the second switching tube and the control end of the second switching tube.
Optionally, the conditioning unit comprises: a first end of the third switching tube is connected with the control end of the first switching tube, a second end of the third switching tube is connected with the second end of the first switching tube, and the control end of the third switching tube is connected with the voltage detection unit; and the fourth resistor is connected between the control end of the third switching tube and the second end of the third switching tube.
Optionally, the conditioning unit may further comprise: the fifth resistor and the first capacitor are connected in series and bridged between the control end of the third switching tube and the first end of the third switching tube; and the second capacitor is connected between the control end of the third switching tube and the first end of the third switching tube in a bridging mode.
Optionally, at least one of the first switch tube, the second switch tube and the third switch tube is a unipolar transistor, a control end of the unipolar transistor is a gate, a first end of the unipolar transistor is a drain, and a second end of the unipolar transistor is a source.
Optionally, at least one of the first switch tube, the second switch tube and the third switch tube is a bipolar transistor, a control end of the bipolar transistor is a base electrode, a first end of the bipolar transistor is a collector electrode, and a second end of the bipolar transistor is an emitter electrode.
Optionally, the method may further include: the second voltage stabilizing diode is connected with the control end of the first switching tube and the second end of the first switching tube; and the sixth resistor is connected between the control end of the first switching tube and the ground.
Optionally, the voltage of the first end of the first switch tube in the first preset range may include: the voltage of the first end of the first switch tube oscillates within the first preset range.
The application also provides a vehicle-mounted power supply which comprises any one of the overvoltage protection circuits.
Optionally, the vehicle-mounted power supply may further include: the input capacitor is connected between the input end of the overvoltage protection circuit and the ground in parallel; the output capacitor is connected with the output end of the overvoltage protection circuit in parallel; the input diode is connected to the input end of the overvoltage protection circuit in a cascade mode; and the power supply module is cascaded to the output end of the overvoltage protection circuit.
The application also provides a vehicle-mounted terminal, which comprises the vehicle-mounted power supply and/or the overvoltage protection circuit.
The application also provides a commercial vehicle, which comprises any one of the vehicle-mounted terminals, any one of the vehicle-mounted power supplies and any one of the overvoltage protection circuits.
Some embodiments of the present application provide an overvoltage protection circuit that can be automatically controlled by a closed-loop circuit including a first switching tube, a voltage detection unit, and a conditioning unit, and adjust an output voltage within a first preset range. When the voltage detection unit detects that the voltage of the output end exceeds the voltage threshold, the conditioning unit can control the first switching tube to be turned off, so that the electric connection between the input end and the output end is cut off, and the overvoltage of a power supply from the input end is prevented from being transmitted to the output end. When the input end is connected with an automobile power supply and the output end is connected with a main power supply module of the vehicle-mounted terminal, the overvoltage protection circuit can effectively protect the main power supply module and the vehicle-mounted terminal from being damaged.
Since the overvoltage protection circuit does not include a power absorption device, most devices of the overvoltage protection circuit are not high in power when a power supply voltage impact with larger energy occurs. Therefore, the power supply voltage impact with larger energy can not damage the overvoltage protection circuit provided by the application. The vehicle-mounted terminal containing the overvoltage protection circuit cannot be damaged.
The overvoltage protection circuit provided by the application can comprise a regulator, and the regulator can delay the starting action when the overvoltage protection circuit tries to start again. So that a certain hysteresis link exists in a closed loop circuit of the overvoltage protection circuit. When the automobile power supply is in an overvoltage state for a long time, the hysteresis link can enable the overvoltage protection circuit to be in an oscillation state. The oscillation state can ensure that the first switching tube is switched between an off state and a saturation conducting state, and the first switching tube is ensured not to enter an amplification region. Therefore, the power damage of the first switching tube can be reduced, and the damage probability of the first switching tube is reduced. And the power requirement of the first switching tube can be reduced, and the production cost of the overvoltage protection circuit is reduced.
Meanwhile, the regulator cannot delay the protection action of the overvoltage protection circuit. Therefore, the overvoltage protection circuit can be ensured to quickly and effectively protect the rear-stage circuit.
Further embodiments of the present application provide a vehicle terminal including any of the aforementioned over-voltage protection circuits. The overvoltage protection circuit has strong protection capability. Therefore, the vehicle-mounted terminal has better power supply front end protection capability. The automobile power supply can work in a relatively severe power supply environment and can adapt to automobiles with poor power supply systems. Therefore, the vehicle-mounted terminal has better adaptability, longer service life and better working stability.
Further embodiments of the present application provide a commercial vehicle comprising any of the aforementioned vehicle terminals and/or any of the aforementioned over-voltage protection circuits. The overvoltage protection circuit and the vehicle-mounted terminal have good power supply front end protection capability. Therefore, the service life of the commercial vehicle is longer, and the commercial vehicle works more stably.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without exceeding the protection scope of the present application.
Fig. 1 shows a schematic diagram of an overvoltage protection circuit for a power supply port of a vehicle power supply in the prior art.
Fig. 2 shows a schematic diagram of an embodiment of the overvoltage protection circuit of the present application.
Fig. 3 is a circuit analysis diagram illustrating a conduction process of the switching tube Q1 of the voltage protection circuit shown in fig. 2.
Fig. 4 is a circuit analysis diagram illustrating a conduction process of the switching tube Q1 of the voltage protection circuit shown in fig. 2.
Fig. 5 shows a schematic diagram of the voltage waveforms applied to the input of the overvoltage protection circuit of fig. 2.
Fig. 6 shows a schematic circuit diagram of a vehicle-mounted terminal according to another embodiment of the present application.
Detailed Description
The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are some, but not all, embodiments of the present application. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.
Fig. 1 shows a schematic diagram of an overvoltage protection circuit for a power supply port of a vehicle power supply in the prior art.
As shown, the overvoltage protection circuit 1000 may be disposed between the input terminal of the main power module and the vehicle power supply. The overvoltage protection circuit 1000 may include a TVS diode DV1 connected in parallel between the positive/negative poles of the vehicle power source. When high-voltage pulse appears on the automobile power supply, the TVS diode can be subjected to overvoltage breakdown and absorb electric energy on the automobile power supply. And the main power supply module protects the rear stage of the overvoltage protection circuit.
However, the overvoltage protection circuit 1000 can protect the subsequent circuit only against a transient high voltage surge of a certain magnitude. When the energy of the transient high voltage surge is too large, or the holding time of the high voltage surge is too long, the TVS diode DV1 may be burned out. Thereby causing damage to the overvoltage protection circuit 1000 and the rear-stage main power module. The in-vehicle terminal including the overvoltage protection circuit 1000 may not be able to operate normally accordingly.
The working voltage range of the current vehicle-mounted terminal is only 9V-36V. At present, the power supply systems of some automobiles on the market are poor in design and have large power supply fluctuation. Voltage impact with relatively large energy is easy to occur on the automobile power supply end. The vehicle-mounted terminal for performing power supply front end overvoltage protection by using the overvoltage protection circuit 10000 is easy to damage and difficult to adapt to various vehicles in the market.
Fig. 2 shows a schematic diagram of an embodiment of the overvoltage protection circuit of the present application.
As shown in fig. 2, the overvoltage protection circuit 2000 may be used for on-board terminal power supply front-end overvoltage protection. The overvoltage protection circuit 2000 may be connected between an input interface of a power converter of the in-vehicle terminal and a power interface of the vehicle. The method can be used for protecting the vehicle-mounted terminal from being damaged due to overvoltage on the vehicle power supply.
The over-voltage on the vehicle power supply may include a voltage surge superimposed on the vehicle power supply. For example, when the automobile is ignited, the operation of the engine is unstable, and voltage shock superimposed on the automobile power supply may be caused. During the running of the automobile, the voltage impact superposed on the automobile power supply is caused by the discharge of the spark plug. The aforementioned overvoltages may also include longer periods of vehicle power over-voltages due to some fault factor.
As shown IN fig. 2, the overvoltage protection circuit 1000 may include an input terminal IN and an output terminal OUT. The input end IN can be connected with an automobile power interface, and the output end OUT can be connected with a power converter of the vehicle-mounted terminal.
The overvoltage protection circuit 1000 as shown in fig. 2 may include: a switching tube Q1, a voltage detection unit 12 and a conditioning unit 13. The switching tube Q1 may be connected to the output terminal OUT, and may be used to control on/off between the input terminal IN and the output terminal OUT. The voltage detection unit 12 may be used for detecting the voltage V of the output terminal OUToutWhether or not to exceed a voltage threshold VTH1. When the voltage V isoutExceeds a voltage threshold VTH1The conditioning unit 13 may trigger a protection action to turn off the switching tube Q1 and cut off the electrical connection between the input terminal IN and the output terminal OUT. The switch tube Q1, the voltage detection unit 12 and the conditioning unit 13 can be connected in a closed loop manner to automatically control the voltage VoutIs in a first preset range. .
As shown in fig. 2, the switching tube Q1 may be the main switch of the overvoltage protection circuit 2000. Controlling the on/off between the input terminal IN and the output terminal OUT. The switching transistor Q1 may be a unipolar transistor or a bipolar transistor. For example, the switching transistor Q1 may be an N-channel fet or a P-channel fet. The switching tube Q1 may be a PNP transistor or an NPN transistor. Alternatively, the switching tube Q1 may also be an IGBT.
The control terminal of the switching tube Q1 may be a base or a gate. The first end of the switching tube Q1 may be a collector or a drain. The second terminal of the switching transistor Q1 may be an emitter or a source.
As shown in the exemplary embodiment of fig. 2, the switching transistor Q1 is a P-channel fet. The control end of the switch tube is a grid electrode, the first end is a drain electrode, and the second end is a source electrode. A first terminal of the switching tube Q1 may be connected to the output terminal OUT. A second terminal of the switching tube Q1 may be connected to the input terminal IN. The control terminal of the switching tube Q1 may be connected to the conditioning unit 13.
As shown in fig. 2, the voltage detecting unit 12 may be used for detecting the voltage V of the output terminal OUToutWhether or not to exceed a voltage threshold VTH1. For example, the voltage detecting unit 12 may be connected to a first end of the switching tube Q1. I.e., the voltage detecting unit 12 may be connected to the output terminal OUT.
The voltage detection unit 12 may include a zener diode D1 and a resistor R1 as shown in fig. 2. The zener diode D1 and the resistor R1 may be connected in series. A cathode of the zener diode D1 may be connected to the output terminal OUT, and an anode of the zener diode D1 may be connected to the resistor R1. The resistor R1 may be connected between the anode of the zener diode D1 and ground.
At a voltage VoutWhen the nominal value of the zener diode D1 is exceeded, the zener diode D1 is Zener broken and turned on so that the two ends of the resistor R1 are approximately equal to the voltage VoutThe nominal voltage of zener diode D1 is subtracted.
As shown in fig. 2, the voltage detection unit 12 may include a switching tube Q2. The switching tube Q2 may be a unipolar transistor or a bipolar transistor. The switching transistor Q2 may be an N-channel fet or a P-channel fet. The switching tube Q2 may be an NPN transistor or a PNP transistor. According to the type of the switching tube Q2, the control terminal of the switching tube Q2 may be a base or a gate. The first end of the switching tube Q2 may be a drain or a collector. The second terminal of the switching transistor Q2 may be a source or an emitter.
As shown in the exemplary embodiment, the switching transistor Q2 is an NPN transistor. The control terminal of the switching tube Q2 may be connected to the anode of the zener diode D1. A first end of the switching tube Q2 may be connected to the conditioning unit 13. A second terminal of the switching tube Q2 may be connected to ground.
Optionally, the first predetermined range may be 0 to 36V. Alternatively, the aforementioned voltage threshold VTH1May be a voltage value within the first predetermined range, close to the upper limit of the first predetermined range. Alternatively, zener diode D1 may be selected to be a nominal 33V zener diode. Since the switch tube Q2 is a triode, its threshold value is 0.7V. Thus, the voltage threshold V is nowTH1About 33.7V.
When the voltage V of the output terminal OUToutGreater than a voltage threshold VTH1When the switch Q2 is turned on, the conditioning unit 13 is driven to operate. This action may include turning off the switch Q1 or reducing the on current of the switch Q1. Thereby reducing the voltage VoutSo as to maintain it within the first predetermined range.
As shown in fig. 2, the voltage detection unit 12 may further include a resistor R2 and a resistor R3. Wherein the resistor R2 may be connected between the second end of the switching tube Q2 and ground. The resistor R2 may be used to limit the current flowing through the first and second terminals of the switch Q2, protecting the switch Q2. A resistor R3 may be connected across the control terminal and the second current terminal of the switch Q2. Resistor R3 may be used to bleed off residual charge at the control terminal of switch Q2. Prevent the switch tube Q2 from generating malfunction due to induction interference.
As shown in fig. 2, the conditioning unit 13 may be configured to adjust the voltage at the control terminal of the switching tube Q1 according to the detection result of the voltage detecting unit 12, so that the voltage at the first terminal of the switching tube Q1 is within a first preset range. Namely, the voltage V of the output end OUT can be adjustedoutWithin a first preset range.
As shown in fig. 2, the conditioning unit 13 may include a switching tube Q3. The switching transistor Q3 may be a unipolar transistor or a bipolar transistor. The switching transistor Q3 may be an N-channel fet or a P-channel fet. The switching tube Q3 may be an NPN transistor or a PNP transistor. According to the type of the switching tube Q3, the control terminal of the switching tube Q3 may be a base or a gate. The first end of the switching tube Q3 may be a drain or a collector. The second terminal of the switching transistor Q3 may be a source or an emitter.
As shown in fig. 2, the switching transistor Q3 is a PNP transistor. The control terminal of the switching tube Q3 may be connected to the voltage detection unit 12. The first terminal of the switching tube Q3 may be connected to the control terminal of the switching tube Q1. The second terminal of the switching tube Q3 may be connected to the second terminal of the switching tube Q1, i.e., may be connected to the input terminal IN. The switching tube Q3 can be used to adjust the control terminal voltage of the switching tube Q1 according to the output of the voltage detection unit 12.
As shown in fig. 2, the conditioning unit 13 may also include a resistor R4. The resistor R4 may be connected between the control terminal of the switch Q3 and the second terminal of the switch Q3.
As shown in fig. 2, the overvoltage protection circuit 2000 may further include a resistor R6 and a zener diode D2 connected in series. The zener diode D2 may be connected across the second terminal and the control terminal of the switch Q1. The cathode of the zener diode D2 may be connected to the second terminal of the switching tube Q1, and the anode of the zener diode D2 may be connected to the control terminal of the switching tube Q1. The resistor R6 may be connected between the control terminal of the switching tube Q1 and ground.
As shown in FIG. 2, the voltage Vout at the output terminal OUT is less than the voltage threshold VTH1When the control end voltage of the switching tube Q2 is smaller than the threshold value, the switching tube Q2 is turned off. The voltage detection unit 12 outputs a high resistance state.
At this time, the voltage at the control end of the switch tube Q3 and the voltage V at the input end INinAre equal. The voltage difference between the control terminal and the second terminal of the switching tube Q3 is zero. The switching tube Q3 is thus turned off.
At this time, the control terminal voltage of the switching tube Q1 appears as a voltage division between the zener diode D2 and the resistor R6. The voltage difference between the control terminal and the second terminal of the switching tube Q1 is approximately the nominal value of the zener diode D2. This voltage difference drives the switching tube Q1 to conduct normally. The input terminal IN supplies power to the output terminal OUT, so that the subsequent stage circuit connected with the output terminal OUT can work normally.
As shown in FIG. 2, the voltage Vout at the output terminal OUT is greater than the voltage threshold VTH1When the control end voltage of the switching tube Q2 is larger than the threshold value, the switching tube Q2 is conducted. The voltage detection unit 12 outputs a low level.
The control terminal voltage of the switch Q3 is represented by the divided voltage of the resistor R4 and the resistor R2. The voltage difference between the control terminal and the second terminal of the switch Q3 may be greater than the threshold value of the switch Q3 and cause it to conduct.
When the switching tube Q3 is turned on, the zener diode D2 is short-circuited. The voltage between the control terminal and the second terminal of the switching tube Q1 becomes zero. Which in turn causes the switching tube Q1 to turn off. The electrical connection between the input terminal IN and the output terminal OUT is cut off.
After the subsequent device connected to the output terminal OUT consumes the residual power stored in the capacitor C3, the voltage Vout of the output terminal OUT is again smaller than the voltage threshold VTH1. At this point, the overvoltage protection circuit 2000 repeats the above process, and retries to turn on the switch Q1. If the fault is eliminated at this time, the input terminal IN supplies power to the output terminal OUT normally. If the fault is not eliminated at this time, the switching tube Q1 can be turned off again by continuing the above process. If the fault exists for a long time, the switch tubes are periodically closed/conducted, so that the voltage V is generatedoutAnd keeping the oscillation state within the preset voltage range.
As shown in fig. 2, the conditioning unit 13 may further include a regulator (not shown). The regulator may include a capacitor C2.
The regulator may be used to retard the conduction of the switching tube Q1. The hysteresis effect can cause the output terminal OUT voltage V to be maintained for a long time in the faultoutIn an oscillating state, rather than statically stabilizing at a point. In this oscillation state, the switching tube Q1 repeatedly switches between the off state and the saturation on state without entering the amplification region. Therefore, the switching tube Q1 can maintain a small power. Thereby reducing the damage of the switching tube Q1 caused by overloadThe possibility. And the power requirement of the switching tube Q1 can be reduced, and the production cost of the overvoltage protection circuit 2000 can be reduced.
Moreover, the regulator does not affect the turn-off speed of the switching tube Q1. I.e. the voltage Vout may exceed the voltage threshold V at the output OUTTH1The rapidity of the protection action is ensured. The security of the subsequent device connected to the output terminal OUT is ensured to be effectively protected.
As shown in fig. 2, the regulator may further include a resistor R5 and a capacitor C1 connected in series. Alternatively, the resistor R5 and the capacitor C1 connected in series may be connected across the control terminal of the switch Q3 and the second terminal of the switch Q3. The charging and discharging waveforms of the regulator can be adjusted by using the resistor R5 and the capacitor C1.
Fig. 3 is a circuit analysis diagram illustrating a conduction process of the switching tube Q1 of the voltage protection circuit shown in fig. 2.
As shown IN fig. 3, the voltage V is just applied to the input terminal IN or when the switching tube Q2 is just turned from the on state to the off stateinThe capacitors C1 and C2 are charged through the resistor R4 and the resistor R6. The direction of the flow of the charging current may be as indicated by the arrows in fig. 3. This charging process causes the control terminal voltage of the switching tube Q3 to rise slowly. The control end voltage rising speed of the switching tube Q3 is determined by resistors R4, R5 and R6 and capacitors C1 and C2. The voltage difference between the control terminal voltage of the switching tube Q3 and the second terminal of the switching tube is gradually decreased until the voltage difference is smaller than the threshold value. The switch Q3 is turned off from the on state, and the switch Q1 is turned on from the off state.
Fig. 4 is a circuit analysis diagram illustrating a conduction process of the switching tube Q1 of the voltage protection circuit shown in fig. 2.
As shown in FIG. 4, the voltage Vout at the output terminal OUT exceeds the voltage threshold VTH1When the switch tube Q2 is turned on. The BE junction of the switching tube Q3 forms a current path with the switching tube Q2 and the resistor R2. This current path renders the switching tube Q2 conductive. Since the current path is not affected by the capacitors C1 and/or C2. The switching tube Q3 can be turned on rapidly. The switched-on switching tube Q3 can rapidly short-circuit the zener diode D2 and cause the switching tube Q1 to be rapidly switched offAnd (7) breaking. At the same time, current through the switch Q3 and the switch Q2 may discharge and reverse charge the capacitor C1 and/or the capacitor C2. To ensure that the action of the over-voltage protection circuit 2000 is delayed enough when it tries to turn on the circuit again.
Fig. 5 shows a schematic diagram of the voltage waveforms applied to the input of the overvoltage protection circuit of fig. 2.
The inventor of the present application performed a practical test of the overvoltage protection circuit 2000 by applying the waveform shown IN fig. 5 to the input terminal IN of the overvoltage protection circuit shown IN fig. 2. Experimental results show that the overvoltage protection circuit 2000 meets design requirements.
Fig. 6 shows a schematic circuit diagram of a vehicle-mounted terminal according to another embodiment of the present application.
As shown in fig. 6, the in-vehicle terminal 3000 may include an overvoltage protection module 31. The overvoltage protection module 31 may include any of the aforementioned overvoltage protection circuits.
Optionally, the in-vehicle terminal 3000 may further include an input capacitor C31. An input capacitor C31 is connected in parallel between the input of the overvoltage protection module 31 and ground.
Optionally, the in-vehicle terminal 3000 may further include an output capacitor C32. An output capacitor C32 may be connected in parallel with the output of the overvoltage protection module 31.
Optionally, the in-vehicle terminal 3000 may further include an input diode D31. An input diode D31 is connected in cascade to the input of the overvoltage protection module 31. For example, the input diode D31 may be connected to the positive terminal of the vehicle power supply and the cathode of the input diode D31 may be connected to the input of the overvoltage protection module 31.
Optionally, the in-vehicle terminal 3000 may further include a power module 32. The power supply module 32 may be cascaded at the output of the overvoltage protection module 31. The power supply module 32 may be a main power converter of the in-vehicle terminal 3000.
The in-vehicle terminal 3000 may be used for management of a commercial vehicle. The commercial vehicle may be a passenger-oriented commercial vehicle, such as a taxi, a bus, a school bus or any other passenger vehicle. It may also be a commercial vehicle for freight purposes, such as a slag car, a hazardous material car or other freight car. And the vehicle can also be a special vehicle for engineering application, such as a commercial concrete vehicle.
For the commercial vehicles, government regulatory agencies and fleet themselves have special regulatory requirements. The vehicle-mounted terminal 3000 built in the target commercial vehicle can detect the running state of the target commercial vehicle at any time, and can effectively restrain the driver, so that the driving process of the driver meets the requirements. When the driver of the target commercial vehicle seriously violates the relevant regulations, the energy supply of the target commercial vehicle can be cut off, and the target commercial vehicle is forced to stop.
The commercial vehicle may also be subject to theft. When the commercial vehicle is found to be stolen, the energy supply of the commercial vehicle can be cut off, so that the commercial vehicle is forced to stop.
The application also provides a commercial vehicle, which comprises any overvoltage protection circuit and/or any vehicle-mounted terminal.
Some embodiments of the present application provide an overvoltage protection circuit that can be automatically controlled by a closed-loop circuit including a first switching tube, a voltage detection unit, and a conditioning unit, and adjust an output voltage within a first preset range. When the voltage detection unit detects that the voltage of the output end exceeds the voltage threshold, the conditioning unit can control the first switching tube to be turned off, so that the electric connection between the input end and the output end is cut off, and the overvoltage of a power supply from the input end is prevented from being transmitted to the output end. When the input end is connected with an automobile power supply and the output end is connected with a main power supply module of the vehicle-mounted terminal, the overvoltage protection circuit can effectively protect the main power supply module and the vehicle-mounted terminal from being damaged.
Since the overvoltage protection circuit does not include a power absorption device, most devices of the overvoltage protection circuit are not high in power when a power supply voltage impact with larger energy occurs. Therefore, the power supply voltage impact with larger energy can not damage the overvoltage protection circuit provided by the application. The vehicle-mounted terminal containing the overvoltage protection circuit cannot be damaged.
The overvoltage protection circuit provided by the application can comprise a regulator, and the regulator can delay the starting action when the overvoltage protection circuit tries to start again. So that a certain hysteresis link exists in a closed loop circuit of the overvoltage protection circuit. When the automobile power supply is in an overvoltage state for a long time, the hysteresis link can enable the overvoltage protection circuit to be in an oscillation state. The oscillation state can ensure that the first switching tube is switched between an off state and a saturation conducting state, and the first switching tube is ensured not to enter an amplification region. Therefore, the power damage of the first switching tube can be reduced, and the damage probability of the first switching tube is reduced. And the power requirement of the first switching tube can be reduced, and the production cost of the overvoltage protection circuit is reduced.
Meanwhile, the regulator cannot delay the protection action of the overvoltage protection circuit. Therefore, the overvoltage protection circuit can be ensured to quickly and effectively protect the rear-stage circuit.
Further embodiments of the present application provide a vehicle terminal including any of the aforementioned over-voltage protection circuits. The overvoltage protection circuit has strong protection capability. Therefore, the vehicle-mounted terminal has better power supply front end protection capability. The automobile power supply can work in a relatively severe power supply environment and can adapt to automobiles with poor power supply systems. Therefore, the vehicle-mounted terminal has better adaptability, longer service life and better working stability.
Further embodiments of the present application provide a commercial vehicle comprising any of the aforementioned vehicle terminals and/or any of the aforementioned over-voltage protection circuits. The overvoltage protection circuit and the vehicle-mounted terminal have good power supply front end protection capability. Therefore, the service life of the commercial vehicle is longer, and the commercial vehicle works more stably.
The foregoing detailed description of the embodiments of the present application has been presented to illustrate the principles and implementations of the present application, and the description of the embodiments is only intended to facilitate the understanding of the methods and their core concepts of the present application. Meanwhile, a person skilled in the art should, according to the idea of the present application, change or modify the embodiments and applications of the present application based on the scope of the present application. In view of the above, the description should not be taken as limiting the application.
Claims (13)
1. An overvoltage protection circuit for a vehicle terminal power input port, comprising:
a first end of the first switch tube is connected with the output end of the overvoltage protection circuit, and a second end of the first switch tube is connected with the input end of the overvoltage protection circuit;
the voltage detection unit is used for detecting the voltage of the first end of the first switching tube;
and the conditioning unit is used for adjusting the voltage of the control end of the first switch tube according to the voltage detection unit so that the voltage of the first end of the first switch tube is in a first preset range.
2. The overvoltage protection circuit of claim 1, wherein the voltage detection unit comprises:
a first zener diode and a first resistor connected in series, wherein
The first voltage stabilizing diode is connected to the first end of the first switching tube;
the first resistor is grounded.
3. The overvoltage protection circuit of claim 2, wherein the voltage detection unit further comprises:
a second switch tube for controlling the current flowing through the first switch tube,
the control end of the second switch tube is connected with the first voltage-stabilizing diode and the first resistor,
the first end of the second switch tube is connected with the conditioning unit.
4. The overvoltage protection circuit of claim 3, wherein the voltage detection unit further comprises:
the second resistor is connected between the second end of the second switch tube and the ground;
and the third resistor is connected between the second end of the second switching tube and the control end of the second switching tube.
5. The overvoltage protection circuit of claim 3, wherein the conditioning unit comprises:
a third switching tube, a second switching tube and a third switching tube,
the first end of the third switch tube is connected with the control end of the first switch tube,
the second end of the third switch tube is connected with the second end of the first switch tube,
the control end of the third switching tube is connected with the voltage detection unit;
and the fourth resistor is connected between the control end of the third switching tube and the second end of the third switching tube.
6. The overvoltage protection circuit of claim 5, wherein at least one of the first switch tube, the second switch tube, and the third switch tube is a unipolar transistor.
7. The overvoltage protection circuit of claim 5, wherein at least one of the first switch tube, the second switch tube, and the third switch tube is a bipolar transistor.
8. The overvoltage protection circuit of claim 5, wherein the voltage at the first terminal of the first switching tube in a first predetermined range comprises:
the voltage of the first end of the first switch tube oscillates within the first preset range.
9. The overvoltage protection circuit of claim 8, wherein the conditioning unit further comprises:
the regulator delays the conduction speed of the first switching tube and does not influence the turn-off speed of the first switching tube;
the regulator includes:
the second capacitor is connected between the control end of the third switching tube and the first end of the third switching tube in a bridging mode;
and the fifth resistor and the first capacitor are connected in series and are connected between the control end of the third switching tube and the first end of the third switching tube in a bridge mode.
10. The overvoltage protection circuit of claim 1, further comprising:
the second voltage stabilizing diode is connected with the control end of the first switching tube and the second end of the first switching tube;
and the sixth resistor is connected between the control end of the first switching tube and the ground.
11. A vehicle terminal comprising the overvoltage protection circuit of any one of claims 1 to 10.
12. The in-vehicle terminal according to claim 11, characterized by further comprising:
the input capacitor is connected between the input end of the overvoltage protection circuit and the ground in parallel;
the output capacitor is connected in parallel with the output end of the overvoltage protection circuit;
the input diode is connected to the input end of the overvoltage protection circuit in a cascade mode;
and the power supply module is cascaded to the output end of the overvoltage protection circuit.
13. Commercial vehicle, characterized in that it comprises a vehicle terminal according to any of claims 11, 12, and/or
The overvoltage protection circuit of any one of claims 1 to 10.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110798992.7A CN113690846A (en) | 2021-07-15 | 2021-07-15 | Overvoltage protection circuit, vehicle-mounted terminal and commercial vehicle |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110798992.7A CN113690846A (en) | 2021-07-15 | 2021-07-15 | Overvoltage protection circuit, vehicle-mounted terminal and commercial vehicle |
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| CN113690846A true CN113690846A (en) | 2021-11-23 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN202110798992.7A Pending CN113690846A (en) | 2021-07-15 | 2021-07-15 | Overvoltage protection circuit, vehicle-mounted terminal and commercial vehicle |
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