WO2023092883A1 - 可防止错误电压接入的保护电路 - Google Patents
可防止错误电压接入的保护电路 Download PDFInfo
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- WO2023092883A1 WO2023092883A1 PCT/CN2022/078750 CN2022078750W WO2023092883A1 WO 2023092883 A1 WO2023092883 A1 WO 2023092883A1 CN 2022078750 W CN2022078750 W CN 2022078750W WO 2023092883 A1 WO2023092883 A1 WO 2023092883A1
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- 230000001681 protective effect Effects 0.000 title abstract description 6
- 239000003990 capacitor Substances 0.000 claims abstract description 43
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- 230000007774 longterm Effects 0.000 description 2
- 238000000034 method Methods 0.000 description 2
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H11/00—Emergency protective circuit arrangements for preventing the switching-on in case an undesired electric working condition might result
- H02H11/006—Emergency protective circuit arrangements for preventing the switching-on in case an undesired electric working condition might result in case of too high or too low voltage
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H11/00—Emergency protective circuit arrangements for preventing the switching-on in case an undesired electric working condition might result
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- the invention relates to protection circuit technology.
- Port protection devices currently on the market can only protect short-term surge voltages, but cannot protect high-voltage DC voltages and high-voltage AC voltages that have been misconnected for a long time.
- the technical problem to be solved by the present invention is to provide a protection circuit that can prevent the wrong voltage from being connected.
- the input voltage is a wrong voltage
- it can disconnect the connection from the input terminal to the output terminal and prevent the wrong voltage from being transmitted to the output terminal, thereby preventing The wrong voltage is connected to the downstream electrical equipment, which ensures the power supply reliability and safety of the subsequent electrical equipment, and the implementation cost is low.
- the protection circuit capable of preventing wrong voltage access includes a voltage input terminal, a voltage output terminal, a first unidirectional conduction element, a triode control circuit, a first triode, a first capacitor, and a Darlington tube or a second triode, a first resistor, a second resistor and a relay; the normally open contact of the relay is connected in series between the voltage input terminal and the voltage output terminal; the first unidirectional conducting element has a first terminal and a second terminal, The first unidirectional conduction element allows current to flow from the first end to the second end, the first end of the first unidirectional conduction element is connected to the voltage input end, and the second end of the first unidirectional conduction element is respectively connected to the first resistor The first end, the first end of the first triode, the first end of the first capacitor, and the first end of the Darlington tube or the second triode are connected; the first conduction ends of the triode control circuit are respectively connected to The second end of the first resistor and
- the protection circuit of the embodiment of the present invention is composed of discrete devices, the number of devices is small, and the cost is low.
- the relay When there is a high-voltage DC voltage or an AC voltage input within a preset frequency range, the relay will be disconnected and the voltage output will be turned off, thereby protecting the rear
- the grade electrical equipment plays a protective role, and the protection function is comprehensive;
- the protection circuit of the embodiment of the present invention uses a relay as a switch, which makes full use of the advantages of high voltage resistance and small conduction resistance of the relay, and has a high overall cost performance;
- the protection circuit of the embodiment of the present invention can realize the protection of high DC voltage and high AC voltage at low cost by using a high withstand voltage unidirectional conduction element and a triode;
- the protection circuit of the embodiment of the present invention can protect against high-voltage DC voltage and AC voltage that have been misconnected for a long time.
- FIG. 1 shows a circuit diagram of a protection circuit capable of preventing wrong voltage access according to a first embodiment of the present invention.
- Fig. 2 shows a circuit diagram of a protection circuit capable of preventing wrong voltage access according to a second embodiment of the present invention.
- Fig. 3 shows a circuit diagram of a protection circuit capable of preventing wrong voltage access according to a third embodiment of the present invention.
- FIG. 1 shows a circuit diagram of a protection circuit capable of preventing wrong voltage access according to a first embodiment of the present invention. See Figure 1.
- a protection circuit capable of preventing wrong voltage access according to the first embodiment of the present invention includes a voltage input terminal IN, a voltage output terminal OUT, a first unidirectional conduction element D1, a transistor control circuit 1, a first transistor Q1, The first capacitor C1, the Darlington tube 2, the first resistor R1, the second resistor R2 and the relay K1.
- the normally open contact of the relay K1 is connected in series between the voltage input terminal IN and the voltage output terminal OUT. Wherein, one end of the normally open contact of the relay K1 is connected to the voltage input terminal IN, and the other end of the normally open contact of the relay K1 is connected to the voltage output terminal OUT.
- the first unidirectional conduction element D1 has a first end and a second end, the first unidirectional conduction element D1 allows current to flow from the first end to the second end, the first end of the first unidirectional conduction element D1 is connected to the voltage input terminal IN connection, the second end of the first unidirectional conduction element D1 is respectively connected to the first end of the first resistor R1, the first end of the first triode Q1, the first end of the first capacitor C1, and the Darlington tube 2 The first end connection.
- the first unidirectional conduction element D1 is composed of a first diode D1, the anode of the first diode D1 constitutes the first end of the first unidirectional conduction element, and the cathode of the first diode D1 It constitutes the second end of the first unidirectional conduction element.
- the first conduction end of the triode control circuit 1 is connected to the second end of the first resistor R1 and the controlled end of the first transistor Q1 respectively, and the second conduction end of the triode control circuit 1 is grounded.
- the triode control circuit 1 is used to disconnect the first conduction terminal from the ground when the voltage at the voltage input terminal is lower than or equal to the preset voltage, and to connect the first conduction terminal when the voltage at the voltage input terminal is higher than the preset voltage to ground, so that the first transistor Q1 is turned on.
- the first resistor R1 functions as a voltage divider and a bias resistor.
- the triode control circuit 1 includes a third resistor R3 and a Zener diode ZD1.
- the first end of the third resistor R3 is respectively connected to the second end of the first resistor R1 and the controlled end of the first triode Q1, the second end of the third resistor R3 is connected to the cathode of the Zener diode ZD1, and the Zener diode
- the anode of ZD1 is grounded.
- the third resistor R3 has a function of current limiting.
- the varistor can also be used to replace the Zener diode ZD1, that is, the triode control circuit 1 is composed of a third resistor R3 and a varistor, and the first end of the third resistor R3 is respectively connected to the first end of the first resistor R1.
- the two terminals are connected to the controlled terminal of the first triode Q1, the second terminal of the third resistor R3 is connected to the first terminal of the varistor, and the second terminal of the varistor is grounded.
- the first end of the second resistor R2 is connected to the common point of the second end of the first triode Q1, the second end of the first capacitor C1 and the controlled end of the Darlington tube 2, and the second end of the second resistor R2 grounded.
- the second resistor R2 has a function of current limiting.
- the second end of the Darlington tube 2 is connected to the controlled end of the relay K1.
- the relay K1 is an electromagnetic relay, one end of the electromagnetic coil of the electromagnetic relay is connected to the second end of the Darlington tube 2 , and the other end of the electromagnetic coil of the electromagnetic relay K1 is grounded.
- the protection circuit of this embodiment includes a second unidirectional conduction element D2, the second unidirectional conduction element D2 has a first end and a second end, and the second unidirectional conduction element D2 allows current to flow from the first end to the second end.
- Two terminals, the first end of the second unidirectional conduction element D2 is connected to the other end of the electromagnetic coil of the electromagnetic relay K1, and the second end of the second unidirectional conduction element D2 is connected to one end of the electromagnetic coil of the electromagnetic relay K1.
- the second unidirectional conduction element D2 is composed of a second diode D2, the anode of the second diode D2 constitutes the first end of the second unidirectional conduction element, and the cathode of the second diode D2 It constitutes the second end of the second unidirectional conduction element.
- the second diode D2 is used as a freewheeling diode to protect the electromagnetic relay K1.
- the protection circuit of this embodiment includes a second capacitor C2, the first end of the second capacitor C2 is respectively connected to the voltage input terminal IN and the first end of the first unidirectional conduction element D1, and the second end of the second capacitor C2 end grounded.
- the second capacitor C2 acts as an electrostatic discharge at the input terminal.
- the first transistor Q1 is a PNP transistor, and the controlled terminal, the first terminal and the second terminal of the first transistor Q1 are respectively the base, the emitter and the collector;
- the Darlington tube 2 It is a PNP Darlington tube, and the PNP Darlington tube is composed of two series-connected PNP transistors Q3 and PNP transistors Q4.
- the controlled end, the first end and the second end of the Darlington tube 2 are base, emitter and collector respectively.
- the protection circuit for preventing wrong voltage access has five working conditions:
- the voltage of the input voltage input terminal IN is a normal voltage, that is, between 6V and 20V.
- the voltage applied to the Zener diode ZD1 is lower than the reverse breakdown voltage of the Zener diode ZD1, and the Zener diode ZD1 is in a disconnected state, so that the current cannot flow through the base of the PNP transistor Q1 (that is, the PNP transistor Q1 cannot obtain the control current required for conduction), and the PNP transistor Q1 is cut off.
- the Darlington tube 2 is turned on, the electromagnetic coil of the relay K1 is energized, the contacts of the relay K1 are closed, the current input from the voltage input terminal IN flows to the voltage output terminal OUT through the contacts, and the output voltage Vo of the voltage output terminal OUT is equal to The input voltage Vin of the voltage input terminal IN.
- the voltage of the input voltage input terminal IN is lower than normal voltage, namely Vin is lower than 6V in this example.
- the voltage applied to the Zener diode ZD1 is lower than the reverse breakdown voltage of the Zener diode ZD1 , the Zener diode ZD1 is in a disconnected state, and the PNP transistor Q1 is turned off.
- the Darlington tube 2 is turned on, and the electromagnetic coil of the relay K1 is energized, but because the current flowing to the electromagnetic coil of the relay K1 is too small, the contacts of the relay K1 cannot be closed, so the voltage input terminal IN and the voltage output terminal OUT Disconnected from each other, the electrical equipment connected to the voltage output terminal OUT cannot obtain working voltage.
- the voltage of the input voltage input terminal IN is higher than normal voltage, namely Vin is higher than 20V in this example.
- the voltage applied to the Zener diode ZD1 is greater than the reverse breakdown voltage of the Zener diode ZD1, and the Zener diode ZD1 is turned on and connected to the ground, forming a current path from the controlled end of the PNP transistor Q1 to the ground.
- a control current flow path is provided for the PNP transistor Q1, so the PNP transistor Q1 is turned on. Since the emitter-base bias voltage of the Darlington transistor 2 is clamped to the emitter-collector voltage of the PNP transistor Q1, the Darlington transistor 2 is pinched off.
- the electromagnetic coil of the relay K1 is not powered, the voltage input terminal IN and the voltage output terminal OUT are disconnected from each other, and the electrical equipment connected to the voltage output terminal OUT will not be affected by high DC voltage.
- a lower AC voltage (such as 12V/50Hz AC voltage) is input to the voltage input terminal IN. Due to the unidirectional conduction of the first diode D1, only the forward voltage of the input AC voltage will be applied to the Zener diode ZD1, and the voltage applied to the Zener diode ZD1 is less than the reverse breakdown voltage of the Zener diode ZD1 , the Zener diode ZD1 is in a disconnected state, and the PNP transistor Q1 is cut off.
- the first capacitor C1 is charged in each positive half cycle of the AC voltage, and the first capacitor C1 is discharged through multiple discharge paths in each negative half cycle of the AC voltage, and the multiple discharge paths include the parasitic resistance of the first capacitor C1 , PNP transistor Q1, and Darlington transistor 2 (at this time, the PNP transistor Q1 and Darlington transistor 2 are not conducting, but there will be a leakage current flowing), etc.
- the charge on the first capacitor C1 Before the arrival of the next positive half cycle of the AC voltage, the charge on the first capacitor C1 has been discharged, which is equivalent to the terminal voltage of the first capacitor C1 returning to the initial state, resulting in the charging voltage of the first capacitor C1 being unable to reach The conduction voltage of the Darlington tube 2, so the electromagnetic coil of the relay K1 cannot be energized, and the voltage input terminal IN and the voltage output terminal OUT are disconnected from each other. Since the charges charged on the first capacitor C1 will be discharged in each negative half cycle of the AC voltage, the voltage of the first capacitor C1 will not accumulate, which helps the protection circuit of this embodiment to protect against long-term errors. The connected high-voltage AC voltage plays a protective role.
- Higher AC voltage (such as 230V/50Hz AC voltage) is input to the voltage input terminal IN.
- the first stage refers to the period during which the amplitude of the input voltage Vin rises from 0V to 20V.
- the Zener diode ZD1 is in the off state, the PNP transistor Q1 is cut off, and the current flows from the voltage input terminal IN to the ground through the first capacitor C1 and the second resistor R2 to charge the first capacitor C1.
- the second stage is when the amplitude of the input voltage Vin exceeds 20V From time to time before the input voltage Vin drops to 20V after crossing the voltage peak value.
- the input voltage Vin exceeds 20V
- the voltage applied to the Zener diode ZD1 is greater than the reverse breakdown voltage of the Zener diode ZD1
- the Zener diode ZD1 and the PNP transistor Q1 are turned on, so the first capacitor C1 passes through the PNP transistor Q1 discharges, so that all the charges on the first capacitor C1 are discharged
- the third stage refers to the period from when the amplitude of the input voltage Vin drops to 20V until it drops to 0V.
- the Zener diode ZD1 is in the off state, the PNP transistor Q1 is cut off, and the current flows from the voltage input terminal IN to the ground through the first capacitor C1 and the second resistor R2 to charge the first capacitor C1, but the first capacitor C1
- the charging voltage of the charging voltage is not enough to make the Darlington tube 2 turn on.
- the Zener diode ZD1 In each negative half cycle of the input AC voltage, the Zener diode ZD1 is in the off state, the PNP transistor Q1 is cut off, and the first capacitor C1 is discharged through multiple discharge paths. This process is similar to working condition 4.
- the charge on the first capacitor C1 When the positive half cycle arrives, the charge on the first capacitor C1 has been discharged, which is equivalent to the terminal voltage of the first capacitor C1 returning to the initial state, so the voltage of the first capacitor C1 will not accumulate, causing the first capacitor The charging voltage of C1 cannot reach the conduction voltage of Darlington tube 2 all the time.
- the Darlington tube 2 is always in the cut-off state, the electromagnetic coil of the relay K1 cannot be powered, and the voltage input terminal IN and the voltage output terminal OUT are disconnected from each other. Electrical equipment connected to the voltage output terminal OUT will not be affected by high AC voltage.
- the size of the first capacitor C1 is set to microfarad level, so that the protection circuit of this embodiment is suitable for 12Vac/50Hz, 24Vac/60Hz, 36Vac/60Hz, 100Vac/50Hz, 110Vac/60Hz, 220Vac/50Hz and 230Vac/50Hz AC voltage can play a protective role.
- the protection circuit of this embodiment of the present invention can realize protection against high DC voltage (up to 500V) and high AC voltage ( Up to 230V/50Hz) protection, and can protect against long-term high-voltage DC voltage and high-voltage AC voltage.
- the first diode D1 protects the PNP transistor Q1 and the Darlington transistor 2 .
- the embodiment of the present invention uses a relay as a switch, which fully utilizes the advantages of the relay's high voltage resistance and small on-resistance, and has a high overall cost performance. If a semiconductor switch is used, either the withstand voltage is low, or the on-resistance is large, and the cost is also high.
- Fig. 2 shows a schematic circuit diagram of a protection circuit according to a second embodiment of the present invention.
- the main difference between the second embodiment and the first embodiment is that the Darlington transistor 2 in the first embodiment is replaced by the second triode Q2 in the second embodiment.
- the second transistor Q2 is a PNP transistor.
- Fig. 3 shows a schematic circuit diagram of a protection circuit according to a third embodiment of the present invention.
- the main difference between the third embodiment and the first embodiment is that in the third embodiment, a fourth resistor R4 connected in parallel with the first capacitor C1 is added.
- the fourth resistor R4 can accelerate the charge discharge speed of the first capacitor C1 during the negative half cycle of the AC voltage.
- the protection circuit of the embodiment of the present invention can be applied to the power interface of an automobile.
- the protection circuit will play a blocking role, preventing the wrong voltage from being transmitted to the low-voltage power supply network and damaging the low-voltage controller and low-voltage electrical appliances inside the car.
- the protection circuit in the embodiment of the present invention is composed of discrete devices, the number of devices is small, and the cost is low.
- the relay When there is a high-voltage DC voltage or an AC voltage input within a preset frequency range, the relay will be disconnected and the voltage output will be turned off, so as to protect the subsequent stage. Electrical equipment plays a protective role.
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Abstract
一种可防止错误电压接入的保护电路,包括第一单向导通元件、三极管控制电路、第一三极管、第一电容、达林顿管、第一电阻、第二电阻及继电器。继电器触点串联在输入端与输出端之间。第一单向导通元件的第一端与输入端连接,第二端分别与第一电阻、第一三极管、第一电容、达林顿管的第一端连接。三极管控制电路分别连接第一电阻的第二端和第一三极管的受控端,达林顿管的第二端与继电器受控端连接。本发明在有错误电压输入时能断开输入端到输出端的连接。
Description
本发明涉及保护电路技术。
随着汽车的智能化和电动化的发展,搭接电源的情况越来越多,用市电、高压直流电去给汽车充电已经成为普遍现象。许多汽车上的电源接口是工作电压为12V或24V的低压电源接口,当诸如高压直流、交流电(包括市电)误接入到该低压电源接口时,如果没有错误电压接入保护,将造成汽车内部的低压控制器和低压用电器损坏,甚至起火。目前市场上的端口保护器件,诸如压敏电阻、TVS二极管、保险丝等,其只能实现对短时浪涌电压的保护,无法对长时间误接的高压直流电压和高压交流电压进行保护。
发明内容
本发明所要解决的技术问题在于提供一种可防止错误电压接入的保护电路,其在输入电压为错误电压时,能够断开输入端到输出端的连接,阻止错误电压传递到输出端,从而防止错误电压接入到后级用电设备,保证了后级用电设备的供电可靠性和安全性,且实施成本低廉。
根据本发明实施例的可防止错误电压接入的保护电路,包括电压输入端、电压输出端、第一单向导通元件、三极管控制电路、第一三极管、第一电容、达林顿管或第二三极管、第一电阻、第二电阻以及继电器;继电器的常开触点串联在电压输入端与电压输出端之间;第一单向导通元件具有第一端和第二端,该第一单向导通元件允许电流从第一端流向第二端,第一单向导通元件的第一端与电压输入端连接,第一单向导通元件的第二端分别与第一电阻的第一端、第一三极管的第一端、第一电容的第一端、以及达林顿管或第二三极管的第一端连接;三极管控制电路的第一导通端分别连接第一电阻的第二端和第一三极管的受控端,三极管控制电路的第二导通端接地;三极管控制电路用于在 电压输入端的电压低于或等于预设电压时使第一导通端与地断开,在电压输入端的电压高于预设电压时使第一导通端接通到地,以使第一三极管导通;第二电阻的第一端连接于第一三极管的第二端、第一电容的第二端以及达林顿管或第二三极管的受控端的共接点,第二电阻的第二端接地;达林顿管或第二三极管的第二端与继电器的受控端连接。
本发明至少具有以下优点:
1、本发明实施例的保护电路由分立器件构成,器件数量少,成本低,在有高压直流电压或预设频率范围内的交流电压输入时都会断开继电器,关断电压输出,从而对后级用电设备起到保护作用,保护功能全面;
2、本发明实施例的保护电路使用继电器作为开关,充分利用了继电器耐高压且导通电阻小的优势,综合性价比高;
3、本发明实施例的保护电路通过使用高耐压的单向导通元件和三极管,能以低成本实现对高直流电压和高交流电压的防护;
4、本发明实施例的保护电路能够针对长时间误接的高压直流电压和交流电压起到保护作用。
附图概述
下面结合附图对本发明作进一步说明。
图1示出了根据本发明第一实施例的可防止错误电压接入的保护电路的电路图。
图2示出了根据本发明第二实施例的可防止错误电压接入的保护电路的电路图。
图3示出了根据本发明第三实施例的可防止错误电压接入的保护电路的电路图。
下面结合附图和具体实施例对本发明进行详细说明。
图1示出了根据本发明第一实施例的可防止错误电压接入的保护电路的电 路图。请参阅图1。根据本发明第一实施例的一种可防止错误电压接入的保护电路包括电压输入端IN、电压输出端OUT、第一单向导通元件D1、三极管控制电路1、第一三极管Q1、第一电容C1、达林顿管2、第一电阻R1、第二电阻R2以及继电器K1。
继电器K1的常开触点串联在电压输入端IN与电压输出端OUT之间。其中,继电器K1的常开触点的一端与电压输入端IN连接,继电器K1的常开触点的另一端与电压输出端OUT连接。
第一单向导通元件D1具有第一端和第二端,第一单向导通元件D1允许电流从第一端流向第二端,第一单向导通元件D1的第一端与电压输入端IN连接,第一单向导通元件D1的第二端分别与第一电阻R1的第一端、第一三极管Q1的第一端、第一电容C1的第一端、以及达林顿管2的第一端连接。在本实施例中,第一单向导通元件D1由第一二极管D1构成,第一二极管D1的阳极构成第一单向导通元件的第一端,第一二极管D1的阴极构成第一单向导通元件的第二端。
三极管控制电路1的第一导通端分别连接第一电阻R1的第二端和第一三极管Q1的受控端,三极管控制电路1的第二导通端接地。三极管控制电路1用于在电压输入端的电压低于或等于预设电压时使第一导通端与地断开,在电压输入端的电压高于上述预设电压时使第一导通端接通到地,以使第一三极管Q1导通。第一电阻R1起到分压和偏置电阻的作用。
在本实施例中,三极管控制电路1包括第三电阻R3以及稳压二极管ZD1。第三电阻R3的第一端分别连接第一电阻R1的第二端和第一三极管Q1的受控端,第三电阻R3的第二端与稳压二极管ZD1的阴极连接,稳压二极管ZD1的阳极接地。第三电阻R3具有限流的作用。
在其它的实施方式中,也可用压敏电阻替代稳压二极管ZD1,即三极管控制电路1由第三电阻R3以及压敏电阻构成,第三电阻R3的第一端分别连接第一电阻R1的第二端和第一三极管Q1的受控端,第三电阻R3的第二端与压敏电阻的第一端连接,压敏电阻的第二端接地。
第二电阻R2的第一端连接于第一三极管Q1的第二端、第一电容C1的第 二端以及达林顿管2的受控端的共接点,第二电阻R2的第二端接地。第二电阻R2具有限流的作用。
达林顿管2的第二端与继电器K1的受控端连接。在本实施例中,继电器K1为电磁继电器,电磁继电器的电磁线圈的一端与达林顿管2的第二端连接,电磁继电器K1的电磁线圈的另一端接地。
进一步地,本实施例的保护电路包括第二单向导通元件D2,第二单向导通元件D2具有第一端和第二端,该第二单向导通元件D2允许电流从第一端流向第二端,第二单向导通元件D2的第一端与电磁继电器K1的电磁线圈的另一端连接,第二单向导通元件D2的第二端与电磁继电器K1的电磁线圈的一端连接。在本实施例中,第二单向导通元件D2由第二二极管D2构成,第二二极管D2的阳极构成第二单向导通元件的第一端,第二二极管D2的阴极构成第二单向导通元件的第二端。第二二极管D2作为续流二极管,对电磁继电器K1起到保护作用。
进一步地,本实施例的保护电路包括第二电容C2,第二电容C2的第一端分别与电压输入端IN和第一单向导通元件D1的第一端连接,第二电容C2的第二端接地。第二电容C2起到输入端静电放电的作用。
在本实施例中,第一三极管Q1为PNP三极管,第一三极管Q1的受控端、第一端和第二端分别为基极、发射极和集电极;达林顿管2为PNP达林顿管,PNP达林顿管由两个串联的PNP三极管Q3和PNP三极管Q4组成。达林顿管2的受控端、第一端和第二端分别为基极、发射极和集电极。
以下以本发明实施例的可防止错误电压接入的保护电路工作于12V车载电源***时说明其工作原理,在12V车载电源***中,输入电压输入端IN的正常电压工作范围为6V~20V。根据本发明实施例的可防止错误电压接入的保护电路具有五种工况:
工况1:
输入电压输入端IN的电压为正常电压,即位于6V~20V之间。此时,施加给稳压二极管ZD1的电压低于稳压二极管ZD1的反向击穿电压,稳压二极管ZD1处于断开状态,使得电流不能流过PNP三极管Q1的基极(即PNP三 极管Q1不能获得导通所需的控制电流),PNP三极管Q1截止。达林顿管2导通,继电器K1的电磁线圈得电,继电器K1的触点吸合,从电压输入端IN输入的电流通过触点流向电压输出端OUT,电压输出端OUT的输出电压Vo等于电压输入端IN的输入电压Vin。
工况2:
输入电压输入端IN的电压低于正常电压,在本示例中即Vin低于6V。此时,施加给稳压二极管ZD1的电压小于稳压二极管ZD1的反向击穿电压,稳压二极管ZD1处于断开状态,PNP三极管Q1截止。达林顿管2导通,继电器K1的电磁线圈得电,但由于流向继电器K1的电磁线圈的电流过小,导致继电器K1的触点无法吸合,因此,电压输入端IN与电压输出端OUT彼此断开,与电压输出端OUT相连的电气设备不能获得工作电压。
工况3:
输入电压输入端IN的电压高于正常电压,在本示例中即Vin高于20V。此时,施加给稳压二极管ZD1的电压大于稳压二极管ZD1的反向击穿电压,稳压二极管ZD1导通,接通到地,形成了PNP三极管Q1的受控端到地的电流通路,为PNP三极管Q1提供了控制电流的流动路径,于是PNP三极管Q1导通。由于达林顿管2的发射极基极偏置电压被钳位至PNP三极管Q1的发射极集电极电压,达林顿管2被夹断截止。继电器K1的电磁线圈不得电,电压输入端IN与电压输出端OUT彼此断开,与电压输出端OUT相连的电气设备不会受到高直流电压的影响。
工况4:
较低的交流电压(例如12V/50Hz的交流电压)输入电压输入端IN。由于第一二极管D1的单向导通作用,只有输入的交流电压的正向电压会加在稳压二极管ZD1上,施加给稳压二极管ZD1的电压小于稳压二极管ZD1的反向击穿电压,稳压二极管ZD1处于断开状态,PNP三极管Q1截止。在交流电压的每个正半周期第一电容C1被充电,在交流电压的每个负半周期,第一电容C1通过多个放电路径放电,该多个放电路径包括第一电容C1的寄生电阻、PNP三极管Q1、达林顿管2(此时PNP三极管Q1和达林顿管2未导通,但会有漏 电流流过)等。在下一个交流电压的正半周期到来之前,第一电容C1上所充的电荷已经放完,相当于第一电容C1的端电压又恢复到初始状态,导致第一电容C1的充电电压始终无法达到达林顿管2的导通电压,因此继电器K1的电磁线圈不能得电,电压输入端IN与电压输出端OUT彼此断开。由于在交流电压的每个负半周期,第一电容C1上所充的电荷都会放完,因此第一电容C1的电压不会积累,这有助于本实施例的保护电路能够针对长时间误接的高压交流电压起到保护作用。
工况5:
较高的交流电压(例如230V/50Hz的交流电压)输入电压输入端IN。
输入的交流电压的每个正半周期分为三个不同的工作阶段:第一阶段是指输入电压Vin的幅值从0V上升至20V的这一段时间。在第一阶段,稳压二极管ZD1处于断开状态,PNP三极管Q1截止,电流从电压输入端IN经第一电容C1、第二电阻R2流向地,为第一电容C1充电。当输入电压Vin的幅值达到20V时,第一电容C1的端电压仍未被充至能使达林顿管2导通的电压;第二阶段是指从输入电压Vin的幅值超过20V之时起到输入电压Vin越过电压峰值后下降到20V之前的这一段时间。在第二阶段,输入电压Vin超过20V,施加给稳压二极管ZD1的电压大于稳压二极管ZD1的反向击穿电压,稳压二极管ZD1和PNP三极管Q1导通,于是第一电容C1通过PNP三极管Q1放电,使得第一电容C1上所充的电荷都被放完;第三阶段是指从输入电压Vin的幅值下降到20V之时起到降为0V的这一段时间。在第三阶段,稳压二极管ZD1处于断开状态,PNP三极管Q1截止,电流从电压输入端IN经第一电容C1、第二电阻R2流向地,为第一电容C1充电,但第一电容C1的充电电压不足以使达林顿管2导通。
在输入的交流电压的每个负半周期,稳压二极管ZD1处于断开状态,PNP三极管Q1截止,第一电容C1通过多个放电路径放电,这个过程与工况4类似,在下一个交流电压的正半周期到来之时,第一电容C1上所充的电荷已经放完,相当于第一电容C1的端电压又恢复到初始状态,因此第一电容C1的电压不会积累,导致第一电容C1的充电电压始终无法达到达林顿管2的导通电压。
综上所述,当本实施例的保护电路面对工况5时,达林顿管2始终处于截止状态,继电器K1的电磁线圈不得电,电压输入端IN与电压输出端OUT彼此断开,与电压输出端OUT相连的电气设备不会受到高交流电压的影响。
在本实施例中,第一电容C1的大小设为微法拉级,使得本实施例的保护电路对12Vac/50Hz、24Vac/60Hz、36Vac/60Hz、100Vac/50Hz、110Vac/60Hz、220Vac/50Hz和230Vac/50Hz的交流电压都能起到保护作用。本发明本实施例的保护电路通过使用耐高压的第一二极管D1、PNP三极管Q1以及达林顿管2,能以较低的成本实现对高直流电压(高达500V)以及高交流电压(高达230V/50Hz)的防护,并能够针对长时间误接的高压直流电压和高压交流电压起到保护作用。第一二极管D1对PNP三极管Q1以及达林顿管2起到保护作用。另外,本发明实施例使用继电器作为开关,充分利用了继电器耐高压且导通电阻小的优势,综合性价比高,如果使用半导体开关,要么耐压低,要么导通电阻大,成本也较高。
图2示出了根据本发明第二实施例的保护电路的电路原理图。该第二实施例与第一实施例的主要区别在于,在第二实施例中用第二三极管Q2替代了第一实施例中的达林顿管2。在第二实施例中,第二三极管Q2为PNP三极管。单只三极管的耐压和增益足够大时,可以实现与达林顿管同样的效果。
图3示出了根据本发明第三实施例的保护电路的电路原理图。该第三实施例与第一实施例的主要区别在于,在第三实施例中,增加了一个与第一电容C1并联连接的第四电阻R4。第四电阻R4能够加快第一电容C1在交流电压的负半周期期间的电荷泄放速度。
本发明实施例的保护电路可应用于汽车电源接口。当错误电压(如高压直流、交流电)误接汽车电源接口,该保护电路将起到阻挡作用,防止错误电压被传递到低压供电网络而损坏汽车内部的低压控制器和低压用电器。
本发明实施例的保护电路由分立器件构成,器件数量少,成本低,在有高压直流电压或预设频率范围内的交流电压输入时都会断开继电器,关断电压输出,从而对后级用电设备起到保护作用。
Claims (12)
- 一种可防止错误电压接入的保护电路,包括电压输入端、电压输出端、第一单向导通元件、三极管控制电路、第一三极管、第一电容、达林顿管或第二三极管、第一电阻、第二电阻以及继电器;所述继电器的常开触点串联在所述电压输入端与所述电压输出端之间;所述第一单向导通元件具有第一端和第二端,该第一单向导通元件允许电流从第一端流向第二端,所述第一单向导通元件的第一端与所述电压输入端连接,所述第一单向导通元件的第二端分别与所述第一电阻的第一端、所述第一三极管的第一端、所述第一电容的第一端、以及所述达林顿管或第二三极管的第一端连接;所述三极管控制电路的第一导通端分别连接所述第一电阻的第二端和所述第一三极管的受控端,所述三极管控制电路的第二导通端接地;所述三极管控制电路用于在所述电压输入端的电压低于或等于预设电压时使所述第一导通端与地断开,在所述电压输入端的电压高于所述预设电压时使所述第一导通端接通到地,以使所述第一三极管导通;所述第二电阻的第一端连接于所述第一三极管的第二端、所述第一电容的第二端以及所述达林顿管或第二三极管的受控端的共接点,所述第二电阻的第二端接地;所述达林顿管或第二三极管的第二端与所述继电器的受控端连接。
- 根据权利要求1所述的可防止错误电压接入的保护电路,其特征在于,所述三极管控制电路包括第三电阻以及稳压二极管;所述第三电阻的第一端分别连接所述第一电阻的第二端和所述第一三极管的受控端,所述第三电阻的第二端与所述稳压二极管的阴极连接,所述稳压二极管的阳极接地。
- 根据权利要求1所述的可防止错误电压接入的保护电路,其特征在于,所述三极管控制电路包括第三电阻以及压敏电阻,所述第三电阻的第一端分别 连接所述第一电阻的第二端和所述第一三极管的受控端,所述第三电阻的第二端与所述压敏电阻的第一端连接,所述压敏电阻的第二端接地。
- 根据权利要求1所述的可防止错误电压接入的保护电路,其特征在于,所述继电器为电磁继电器,所述电磁继电器的电磁线圈的一端与所述达林顿管或第二三极管的第二端连接,所述电磁继电器的电磁线圈的另一端接地。
- 根据权利要求4所述的可防止错误电压接入的保护电路,其特征在于,所述的保护电路包括第二单向导通元件,所述第二单向导通元件具有第一端和第二端,该第二单向导通元件允许电流从第一端流向第二端,所述第二单向导通元件的第一端与所述电磁继电器的电磁线圈的另一端连接,所述第一单向导通元件的第二端与所述电磁继电器的电磁线圈的一端连接。
- 根据权利要求5所述的可防止错误电压接入的保护电路,其特征在于,所述第二单向导通元件由第二二极管构成,所述第二二极管的阳极构成所述第二单向导通元件的第一端,所述第二二极管的阴极构成第二单向导通元件的第二端。
- 根据权利要求1所述的可防止错误电压接入的保护电路,其特征在于,所述第一单向导通元件由第一二极管构成,所述第一二极管的阳极构成所述第一单向导通元件的第一端,所述第一二极管的阴极构成所述第一单向导通元件的第二端。
- 根据权利要求1所述的可防止错误电压接入的保护电路,其特征在于,所述的保护电路包括第二电容,所述第二电容的第一端分别与所述电压输入端和所述第一单向导通元件的第一端连接,所述第二电容的第二端接地。
- 根据权利要求1所述的可防止错误电压接入的保护电路,其特征在于,所述第一三极管为PNP三极管,所述第一三极管的受控端、第一端和第二端分别为基极、发射极和集电极。
- 根据权利要求1或9所述的可防止错误电压接入的保护电路,其特征在于,所述第二三极管为PNP三极管,所述第二三极管的受控端、第一端和第二端分别为基极、发射极和集电极;所述达林顿管为PNP达林顿管,所述达林顿管的受控端、第一端和第二端 分别为基极、发射极和集电极。
- 根据权利要求10所述的可防止错误电压接入的保护电路,其特征在于,所述PNP达林顿管由两个串联的PNP三极管组成。
- 根据权利要求1所述的可防止错误电压接入的保护电路,其特征在于,所述的保护电路包括第四电阻,所述第四电阻与所述第一电容并联连接。
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CN208623331U (zh) * | 2018-08-06 | 2019-03-19 | 泉州市琪祥电子科技有限公司 | 一种车载对讲机保护电路 |
CN208479167U (zh) * | 2018-08-09 | 2019-02-05 | 深圳市宇芯数码技术有限公司 | 一种过压保护电路 |
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