CN220209947U - Self-protection circuit with temperature compensation, pre-charging circuit and direct current system - Google Patents
Self-protection circuit with temperature compensation, pre-charging circuit and direct current system Download PDFInfo
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- CN220209947U CN220209947U CN202321784656.8U CN202321784656U CN220209947U CN 220209947 U CN220209947 U CN 220209947U CN 202321784656 U CN202321784656 U CN 202321784656U CN 220209947 U CN220209947 U CN 220209947U
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Abstract
The application discloses a self-protection circuit with temperature compensation, a pre-charging circuit and a direct current system, which comprises an electric control switch, wherein the input end of the electric control switch is connected with the input end of a power supply, and the output end of the electric control switch is connected with the output end of the power supply; the current detection circuit is connected with the input end of the electric control switch and is used for detecting the current flowing through the electric control switch and outputting a current signal; the input end of the control circuit is connected with the output end of the current detection circuit, the output end of the control circuit is connected with the control end of the electric control switch, and the control circuit is used for collecting the temperature of the electric control switch, carrying out temperature compensation on the current signal according to the temperature so as to obtain a temperature compensation current signal, and driving the electric control switch to be turned off when the temperature compensation current signal reaches a threshold value.
Description
Technical Field
The present disclosure relates to the field of overcurrent protection, and in particular, to a self-protection circuit with temperature compensation, a precharge circuit, and a dc system.
Background
In a direct current system, when electric equipment is connected with direct current input, if internal overcurrent or short circuit occurs, overcurrent protection of the electric equipment is realized by breaking the direct current input, a sampling circuit is adopted in a traditional circuit to collect current flowing through a sampling resistor, the collected current is fed back to a digital processor or a comparator, and when the current is overlarge, the breaking of the direct current input is realized, and the traditional circuit needs to be connected into the digital processor or the comparator, so that extra power consumption and cost are introduced.
Therefore, in the prior art, a method for realizing control of a Metal-Oxide-Semiconductor Field-Effect Transistor (Metal-Oxide-semiconductor field effect transistor) by using a Metal Oxide Semiconductor (MOSFET) as a switch and using different voltage drops generated when different currents flow through on-resistances in the MOS transistor is provided, specifically, two triodes are adopted to selectively control on or off of the MOS transistor, bases of the two triodes are connected with each other, one triode samples current by using the on-resistances in the MOS transistor, a collector of the other triode is connected with a gate of the MOS transistor, when the current flowing through the MOS transistor is too large, the base current of the other triode is increased to turn on the transistor, and the triode can output low-level control on-off of the MOS transistor to realize direct current input self-turn-off.
However, the method utilizes the on-resistance in the MOS tube to sample the current, the on-resistance of the MOS tube changes along with the working temperature of the MOS tube, and the base current of the other triode also changes along with the working temperature of the MOS tube under the same current condition, so that the overcurrent protection point of the scheme has larger fluctuation, and the MOS tube is easily closed by mistake under the non-overcurrent condition, thereby influencing the working precision of the self-protection circuit.
Disclosure of Invention
The main purpose of this application is to propose a self preservation protects circuit, precharge circuit and direct current system with temperature compensation, aims at solving because the on resistance of MOS pipe changes along with operating temperature, influences self preservation protects circuit work precision's problem.
The application provides a self preservation protects circuit with temperature compensation, includes:
the electric control switch is provided with an internal resistance, and the input end of the electric control switch is used for being connected with a direct current power supply;
the current detection circuit is connected with the input end of the electric control switch and is used for detecting the current flowing through the electric control switch and outputting a current signal according to the current;
the input end of the control circuit is connected with the output end of the current detection circuit, the output end of the control circuit is connected with the control end of the electric control switch, the control circuit is used for collecting the temperature of the electric control switch, carrying out temperature compensation on the current signal according to the temperature so as to obtain a temperature compensation current signal, and driving the electric control switch to be turned off when the temperature compensation current signal reaches a threshold value.
Optionally, the self-protection circuit further includes:
The output end of the switching circuit is connected with the control end of the electric control switch or the input end of the control circuit, and the switching circuit is used for outputting a turn-off signal to the electric control switch or the control circuit when receiving a command signal so as to turn off the electric control switch.
Optionally, the control circuit includes:
the input end of the temperature compensation circuit is connected with the output end of the current detection circuit, and the temperature compensation circuit is used for collecting the temperature of the electric control switch and outputting the temperature compensation current signal according to the temperature and the current signal;
the input end of the driving circuit is connected with the output end of the temperature compensation circuit, the output end of the driving circuit is connected with the control end of the electric control switch, and the driving circuit is used for driving the electric control switch to be turned off when the temperature compensation current signal reaches the threshold value.
Optionally, the temperature compensation circuit includes:
the thermistor is a positive temperature coefficient thermistor, a first end of the thermistor is connected with the output end of the current detection circuit, and a second end of the thermistor is connected with the input end of the driving circuit;
And the first end of the divider resistor is connected with the public end of the thermistor and the driving circuit, and the second end of the divider resistor is connected with the output end of the electric control switch.
Optionally, the temperature compensation circuit includes:
the first end of the divider resistor is connected with the output end of the current detection circuit, and the second end of the divider resistor is connected with the input end of the driving circuit;
the thermistor is a negative temperature coefficient thermistor, a first end of the thermistor is connected with a public end of the voltage dividing resistor and the driving circuit, and a second end of the thermistor is connected with an output end of the electric control switch.
Optionally, the driving circuit includes:
the base of the second triode is connected with the output end of the temperature compensation circuit, the collector of the second triode is connected with the control end of the electric control switch, the emitter of the second triode is connected with the output end of the electric control switch, and the second triode is used for controlling the electric control switch to be turned on/off.
Optionally, the self-protection circuit further includes:
a control power supply circuit for supplying power to the drive circuit and the current detection circuit;
The driving circuit further includes:
and the first end of the second resistor is connected with the output end of the control power supply circuit, and the second end of the second resistor is connected with the collector electrode of the second triode.
Optionally, the current detection circuit includes:
the base electrode of the first triode is connected with the input end of the temperature compensation circuit, the base electrode of the first triode is in short circuit with the collector electrode of the first triode, and the emitting electrode of the first triode is connected with the input end of the electric control switch;
and the first end of the first resistor is connected with the output end of the control power supply circuit, and the second end of the first resistor is connected with the collector electrode of the first triode.
Optionally, the current detection circuit further includes:
the anode of the second diode is connected with the emitter of the first triode, and the cathode of the second diode is connected with the input end of the electric control switch;
the driving circuit further includes:
and the anode of the third diode is connected with the emitter of the second triode, and the cathode of the third diode is connected with the output end of the electric control switch.
Optionally, the current detection circuit further includes:
the anode of the first diode is connected with the emitter of the first triode, and the cathode of the first diode is connected with the collector of the first triode.
On the other hand, the application also provides a pre-charging circuit, which comprises a pre-charging resistor, a pre-charging capacitor and the self-protection circuit; wherein,
one end of the pre-charging resistor is connected with the input end of the electric control switch of the self-protection circuit, and the other end of the pre-charging resistor is connected with the output end of the electric control switch;
one end of the pre-charge capacitor is connected with the input end of the electric control switch, and the other end of the pre-charge capacitor is grounded.
On the other hand, the application also provides a direct current system which comprises power supply equipment and electric equipment, wherein the direct current system also comprises the self-protection circuit or the pre-charging circuit, and the power supply equipment is connected with the electric equipment through the self-protection circuit or the pre-charging circuit.
According to the self-protection circuit, the control circuit collects the working temperature of the electric control switch, receives a current signal output by the current detection circuit according to the detected current flowing through the electric control switch, performs temperature compensation on the current signal according to the working temperature of the electric control switch, obtains a temperature compensation current signal, and drives the electric control switch to be turned off when the temperature compensation current signal reaches a threshold value, so that under different temperatures, when the current flowing through the electric control switch is detected to not reach the actual maximum current, the obtained temperature compensation current signal does not reach the threshold value after the current detection circuit performs temperature compensation on the current signal correspondingly output according to the detected current, and only when the current flowing through the electric control switch is detected to reach the actual maximum current, the control circuit correspondingly obtains the temperature compensation current signal to reach the threshold value, and drives the electric control switch to be turned off to realize overcurrent protection, so that the maximum current correspondingly flowing through the electric control switch before the electric control switch is turned off does not change along with the temperature change of the electric control switch, the fact that the maximum current flowing through the electric control switch is not actually turned off is avoided, and the working precision of the self-protection circuit is improved. The self-protection circuit can not be influenced by the temperature change of the electric control switch, and can still maintain the current protection point of the self-protection circuit stable when the working temperature of the electric control switch changes.
Drawings
In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings that are required in the embodiments or the description of the prior art will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and that other drawings may be obtained from the structures shown in these drawings without inventive effort to a person of ordinary skill in the art.
FIG. 1 is a schematic diagram of a functional module of an embodiment of a self-protection circuit of the present application;
FIG. 2 is a schematic circuit diagram of an embodiment of the self-protection circuit in FIG. 1;
FIG. 3 is a schematic circuit diagram of another embodiment of the self-protection circuit shown in FIG. 1;
fig. 4 is a schematic circuit diagram of the self-protection circuit in fig. 2 applied in a pre-charge circuit.
Detailed Description
The terms first, second, third and the like in the description and in the claims and drawings are used for distinguishing between different objects and not for limiting the specified sequence.
In the embodiments of the present application, words such as "exemplary" or "such as" are used to mean serving as examples, illustrations, or descriptions. Any embodiment or design described herein as "exemplary" or "for example" should not be construed as preferred or advantageous over other embodiments or designs. Rather, the use of words such as "exemplary" or "such as" is intended to present related concepts in a concrete fashion.
The self-protection circuit with the temperature compensation is widely applied to various power circuits, is connected in series between the input and the output of the power circuit, achieves overcurrent self-protection of the power circuit, can be used as a part of a pre-charging circuit when internal overcurrent or short circuit occurs, and can be used for a battery charging and discharging system, a fan, a sound box or a lighting system.
Referring to fig. 1-3, in one embodiment of the present application, the circuit includes:
the electric control switch is provided with an internal resistance, and the input end of the electric control switch is used for being connected with a direct current power supply;
the current detection circuit is connected with the input end of the electric control switch and is used for detecting the current flowing through the electric control switch and outputting a current signal according to the current;
The input end of the control circuit is connected with the output end of the current detection circuit, the output end of the control circuit is connected with the control end of the electric control switch, the control circuit is used for collecting the temperature of the electric control switch, carrying out temperature compensation on the current signal according to the temperature so as to obtain a temperature compensation current signal, and driving the electric control switch to be turned off when the temperature compensation current signal reaches a threshold value.
In this embodiment, the electric control switch provides internal resistance to provide voltage drop for the current sampling detection circuit to perform current detection, and the self-protection power circuit is turned off through self turn-off, and the electric control switch with internal resistance can be implemented by using a MOS transistor Q3, other switches with internal resistance, or a resistor connected in series with the switch, so long as the purpose of providing internal resistance can be achieved.
When current flows through the electric control switch, voltage drop is generated at two ends of the electric control switch, and the current detection circuit collects the voltage drop at two ends of the electric control switch, so that the potential of the output end of the current detection circuit can be obtained according to the voltage drop, and then the potential is converted into a current signal, and the current signal is output to the control circuit. The larger the current flowing through the switch, the larger the voltage drop, the larger the potential of the output end of the current detection circuit, and the larger the current signal, namely the current signal increases along with the increase of the current flowing through the electric control switch.
The control circuit receives a current signal, if the current signal is not greater than a threshold value, the control circuit outputs a control signal to the control end of the electric control switch to drive the electric control switch to be conducted so as to conduct the self-protection circuit, and if the current signal reaches the threshold value, the current of the electric control switch reaches the overcurrent protection point, the control circuit is driven to be turned off so as to turn off the self-protection circuit. When the current signal is not compensated, the current value of the current signal is affected by temperature, when the temperature rises, the internal resistance of the electric control switch is increased along with the temperature rise resistance, so that the current value of the current signal is reduced, when the temperature falls, the internal resistance of the electric control switch is reduced along with the temperature fall resistance, so that the current value of the current signal is increased, and under the condition of different temperatures, the current value of the current signal fluctuates along with the temperature rise or the temperature fall.
As will be appreciated by those skilled in the art, since the resistance of the internal resistance of the electronically controlled switch varies with the operating temperature thereof, the voltage drop generated when the internal resistance of the different resistances flows through the same current will also vary under the same current condition, resulting in that the current signal output by the current detection circuit will also vary under the same current condition, for example, as the operating temperature of the electronically controlled switch increases as the current passes, the resistance of the internal resistance will also increase under the same current condition, resulting in that the current signal output by the current detection circuit will also increase under the same current condition, if the current flowing through the internal resistance does not reach the overcurrent protection point, but because the resistance of the internal resistance increases with the operating temperature of the electronically controlled switch, the current signal may have reached the threshold value, the control circuit will drive the electronically controlled switch to turn off, thereby resulting in that the current flowing through the electronically controlled switch does not reach the actual overcurrent protection point, in order to solve the problem, and the temperature compensation is performed on the current signal according to the operating temperature, for example, the current signal output by the control circuit will also decrease under the temperature increase condition as the internal resistance increases, the current signal is not reached under the same temperature, the current amplitude is reduced as the current is increased, and the current is not increased under the current is compensated under the conditions, and the current is reduced as the temperature is increased, thereby the current is not increased, and the current is basically is turned off, therefore, the maximum current flowing through the electric control switch before the electric control switch is turned off can not change along with the temperature change of the electric control switch.
When the current flowing through the electric control switch is smaller, the current detected by the current detection circuit does not reach the overcurrent protection point, the control circuit drives the electric control switch to be turned on, the power input by the power input end P1 is output to the load from the power output end P2 through the electric control switch, when the current flowing through the electric control switch is overlarge, the current detection circuit detects that the current flowing through the electric control switch reaches the overcurrent protection point, and the control circuit outputs a control signal to the electric control switch to drive the electric control switch to be turned off, so that the overcurrent of the self-protection circuit is automatically turned off.
According to the self-protection circuit, the control circuit collects the working temperature of the electric control switch, receives a current signal output by the current detection circuit according to the detected current flowing through the electric control switch, performs temperature compensation on the current signal according to the working temperature of the electric control switch, obtains a temperature compensation current signal, and drives the electric control switch to be turned off when the temperature compensation current signal reaches a threshold value, so that under different temperatures, when the current flowing through the electric control switch is detected to not reach the actual maximum current, the obtained temperature compensation current signal does not reach the threshold value after the current detection circuit performs temperature compensation on the current signal correspondingly output according to the detected current, and only when the current flowing through the electric control switch is detected to reach the actual maximum current, the control circuit correspondingly obtains the temperature compensation current signal to reach the threshold value, and drives the electric control switch to be turned off to realize overcurrent protection, so that the maximum current correspondingly flowing through the electric control switch before the electric control switch is turned off does not change along with the temperature change of the electric control switch, the fact that the maximum current flowing through the electric control switch is not actually turned off is avoided, and the working precision of the self-protection circuit is improved. The self-protection circuit can not be influenced by the temperature change of the electric control switch, and can still maintain the current protection point of the self-protection circuit stable when the working temperature of the electric control switch changes.
In an embodiment, the self-protection circuit further comprises:
the output end of the switching circuit is connected with the control end of the electric control switch or the input end of the control circuit, and the switching circuit is used for outputting a turn-off signal to the electric control switch or the control circuit when receiving a command signal so as to turn off the electric control switch.
In this embodiment, when the switch circuit receives a command signal issued by the controller, the switch circuit outputs a turn-off signal for turning off the electric control switch to the electric control switch or the control circuit, for example, in an alternative embodiment, the electric control switch is turned on when high level, and turned off when low level, when the switch circuit directly outputs the turn-off signal to the control end of the electric control switch, the turn-off signal may be a low level, when the switch circuit outputs the turn-off signal to the input end of the control circuit, the control circuit receives the over-current signal and then outputs the low level to the control end of the electric control switch, so that the control circuit turns off the electric control switch, and the action of the controller issuing the command signal may be triggered by a user by pressing an operation mode such as a device button, gesture operation, voice, or by other external signals, so that the controller of the dc system applied by the self-protection circuit can actively control the turn-on/off of the electric control switch through issuing the command signal, thereby increasing the applicability of the self-protection circuit, and being applicable to a power circuit that needs over-current protection, and also needs to be controlled turn-off, for example, to a pre-charge circuit as shown in fig. 4.
In one embodiment, the control circuit includes:
the input end of the temperature compensation circuit is connected with the output end of the current detection circuit, and the temperature compensation circuit is used for collecting the temperature of the electric control switch and outputting the temperature compensation current signal according to the temperature and the current signal;
the input end of the driving circuit is connected with the output end of the temperature compensation circuit, the output end of the driving circuit is connected with the control end of the electric control switch, and the driving circuit is used for driving the electric control switch to be turned off when the temperature compensation current signal reaches the threshold value.
The temperature compensation circuit compensates on the basis of the current signal according to the temperature after collecting the temperature of the internal resistance, and outputs the compensated temperature compensation current signal to the control circuit, for example, under the condition that the internal resistance of the electric control switch increases along with the temperature rise resistance, the current signal output by the current detection circuit increases along with the internal resistance when the internal resistance passes through the same current, in order to avoid that the current flowing through the internal resistance does not reach the actual overcurrent protection point and the current signal reaches the threshold value, the electric control switch is turned off by mistake, the temperature compensation circuit in the embodiment reduces the current signal and outputs the current signal, along with the continuous rise of the temperature, the reduced amplitude can be determined according to the change of the internal resistance along with the temperature, so that the temperature compensation current signal output by the temperature compensation is basically consistent under the condition of ensuring that the internal resistance flows through the same current and different temperatures, the maximum current flowing through the electric control switch correspondingly before the electric control switch is turned off does not change along with the temperature change of the internal resistance of the electric control switch, and the error turning off of the electric control switch is avoided, and the working precision of the self-protection circuit is improved.
It is worth to say that, because the internal resistance of different electric control switches varies with the curve of temperature, if the curve is difficult to fit, the basic stability of the overcurrent protection point is only required to be ensured.
The driving circuit receives the temperature compensation current signal output by the temperature compensation circuit and drives the electric control switch to be turned off when the temperature compensation current signal reaches a threshold value, for example, in an alternative embodiment, the electric control switch is turned on when the electric control switch is at a high level and turned off when the electric control switch is at a low level, and when the temperature compensation current signal reaches the threshold value, the driving circuit outputs a low level to a control end of the electric control switch so as to drive the electric control switch to be turned off.
In one embodiment, a temperature compensation circuit includes:
the thermistor RT1 is a positive temperature coefficient thermistor, a first end of the thermistor RT1 is connected with the output end of the current detection circuit, and a second end of the thermistor RT1 is connected with the input end of the driving circuit;
and a voltage dividing resistor R3, wherein a first end of the voltage dividing resistor R3 is connected with a public end of the thermistor RT1 and the driving circuit, and a second end of the voltage dividing resistor R3 is connected with an output end of the electric control switch.
The output end of the electric control switch can be used as a potential reference point of the self-protection circuit.
For a drive circuit controlled by a voltage signal, when the voltage signal at the input end of the drive circuit reaches a voltage threshold value, the drive circuit drives the electric switch to be turned off, and the voltage signal is positively correlated with the temperature compensation current signal, that is, when the voltage signal reaches the voltage threshold value, the temperature compensation current signal also reaches the threshold value. Therefore, in this embodiment, after the current signal is input into the temperature compensation circuit, the voltage at the output end of the current detection circuit is divided by the thermistor RT1 and the voltage dividing resistor R3, the voltage at the two ends of the voltage dividing resistor R3 can be used as the voltage signal at the input end of the driving circuit, the voltage signal at the input end of the driving circuit is reduced according to the resistance ratio of the thermistor RT1 to the voltage dividing resistor R3, when the temperature of the electric control switch rises, the resistance of the internal resistance of the electric control switch increases, when the same current flows through the internal resistance, the voltage at the output end of the current detection circuit increases, the output current signal increases, and the resistance of the thermistor RT1 is influenced by the temperature of the electric control switch, and also increases, the ratio between the thermistor RT1 and the voltage dividing resistor R3 increases, and the voltage at the two ends of the voltage dividing resistor R3 decreases, namely the voltage signal at the input end of the driving circuit decreases, and the current detection circuit needs to output a larger current signal to enable the voltage signal at the input end of the driving circuit to reach a fixed voltage threshold, that is needed to output a larger current signal to enable the temperature compensation current signal to reach a higher threshold, so as to realize temperature compensation.
For the driving circuit controlled by the current signal, when the current signal at the input end of the driving circuit reaches a current threshold value, the driving circuit drives the electric switch to be turned off. Therefore, in this embodiment, after the current signal is input into the temperature compensation circuit, the current formed by the current signal through the thermistor RT1 is split through the voltage dividing resistor R3, and the current signal input into the input end of the driving circuit after the split is output as a temperature compensation current signal, when the temperature of the electric control switch rises, the resistance value of the internal resistance of the electric control switch increases accordingly, when the internal resistance flows through the same current, the voltage of the output end of the current detection circuit increases, the output current signal increases, and the resistance value of the thermistor RT1 is influenced by the temperature of the electric control switch, and also increases accordingly, the current formed by the current signal through the thermistor RT1 decreases accordingly, and when the current detection circuit needs to output a larger current signal, the current signal input into the driving circuit can reach a fixed current threshold value, that is, when the current detection circuit needs to output a larger current signal, the temperature compensation current signal can reach the threshold value, thereby realizing temperature compensation.
The temperature compensation circuit compensates the current signal output by the current detection circuit from the voltage and current aspects to offset the current signal rising caused by the temperature rising of the electric control switch, so that the temperature compensation current signals output under the condition that the current flowing through the electric control switch is the same under different temperatures are basically consistent, the stability of the overcurrent protection point of the self-protection circuit is ensured, and the working precision of the self-protection circuit is improved.
In another embodiment, a temperature compensation circuit includes:
the first end of the divider resistor is connected with the output end of the current detection circuit, and the second end of the divider resistor is connected with the input end of the driving circuit;
the thermistor is a negative temperature coefficient thermistor, a first end of the thermistor is connected with a public end of the voltage dividing resistor and the driving circuit, and a second end of the thermistor is connected with an output end of the electric control switch.
For the driving circuit controlled by the voltage signal, after the current signal is input into the temperature compensation circuit, the voltage at the output end of the current detection circuit is divided by the thermistor and the voltage dividing resistor, the voltage at the two ends of the thermistor can be used as the voltage signal at the input end of the driving circuit, the voltage signal at the input end of the driving circuit is reduced according to the resistance ratio of the voltage dividing resistor to the thermistor, when the temperature of the electric control switch rises, the resistance value of the internal resistance of the electric control switch increases, when the internal current is choked and the same current flows, the voltage at the output end of the current detection circuit increases, the output current signal increases, the resistance value of the thermistor is influenced by the temperature of the electric control switch and also decreases, the ratio between the voltage dividing resistor and the thermistor rises, the voltage at the two ends of the thermistor decreases, namely the voltage signal at the input end of the driving circuit decreases, the current detection circuit needs to output a larger current signal to enable the voltage signal at the input end of the driving circuit to reach a fixed voltage threshold, that is achieved, that is, and the current detection circuit needs to output a larger current signal to enable the temperature compensation current signal to reach the threshold value, so that temperature compensation is achieved.
For the driving circuit controlled by the current signal, after the current signal is input into the temperature compensation circuit, the current formed by the voltage dividing resistor is shunted through the thermistor, the current signal input into the input end of the driving circuit after shunting is output as a temperature compensation current signal, when the temperature of the electric control switch rises, the resistance value of the internal resistance of the electric control switch increases, when the internal resistance flows through the same current, the voltage of the output end of the current detection circuit increases, the output current signal increases, the resistance value of the thermistor is influenced by the temperature of the electric control switch and also decreases, the current flowing through the thermistor increases, so that the current signal input into the driving circuit after shunting falls, and the current signal input into the driving circuit can reach a fixed current threshold value only when the current detection circuit needs to output a larger current signal, that is, the temperature compensation current signal can reach a threshold value only when the current detection circuit needs to output the larger current signal, and therefore temperature compensation is achieved.
In one embodiment, the driving circuit includes:
the base of the second triode Q2 is connected with the output end of the temperature compensation circuit, the collector of the second triode Q2 is connected with the control end of the electric control switch, the emitter of the second triode Q2 is connected with the output end of the electric control switch, and the second triode Q2 is used for controlling the electric control switch to be turned on/off.
In an embodiment, the second transistor Q2 is an NPN transistor, the collector of the second transistor Q2 is used as the output terminal of the driving circuit, and the base of the second transistor Q2 is used as the input terminal of the driving circuit.
When the base level of the second triode Q2 is higher than the emitter level by one turn-on voltage, the base current is generated, the second triode Q2 is turned on, the collector current of the second triode Q2 is controlled by the base current of the second triode Q2, when the base current is increased, the collector current is increased, the voltage output by the collector is reduced along with the increase of the collector current, when the voltage of the collector of the triode Q2 is lower than the base voltage, the second triode Q2 enters a saturated conduction state, the base current of the second triode Q2 is a temperature compensation current signal, at the moment, the base current of the second triode Q2 can be considered to reach a threshold value, and the collector is considered to output a low-level control signal to the control end of the electric control switch so as to control the electric control switch to be turned off, and overcurrent protection is realized.
When the current flowing through the electric control switch does not flow, when the temperature of the electric control switch rises, the resistance value of the internal resistance of the electric control switch increases along with the rise, the voltage of the output end of the current detection circuit increases, the current signal output by the current detection circuit also increases, the temperature compensation circuit can be composed of a thermistor RT1 and a divider resistor R3, the resistance value of the thermistor RT1 is influenced by the temperature of the electric control switch and also increases along with the rise, the temperature compensation current signal output to the base of the second triode Q2 through temperature compensation is reduced along with the rise of the temperature after the current signal is input into the temperature compensation circuit, so that the influence of the rise of the internal resistance and the rise of the current signal are counteracted, the temperature compensation current signal input to the base of the second triode Q2 does not reach a threshold value, the voltage between the base and the emitter of the second triode Q2 does not reach the conducting voltage of the second triode Q2, the second triode Q2 is cut off, the collector of the second triode Q2 is output high level, the electric control switch continues to keep in a normal conducting state, and accordingly the error conducting precision of the second triode Q2 is avoided when the overcurrent protection circuit does not flow, and the error conducting precision of the second triode Q2 is not increased along with the rise of the temperature.
The driving circuit is realized by a simple semiconductor device, does not have a digital device, and has the advantages of simple structure and lower cost.
In an embodiment, the self-protection circuit further comprises:
a control power supply circuit V1, the control power supply circuit V1 being configured to supply power to the driving circuit and the current detection circuit;
the driving circuit further includes:
and a first end of the second resistor R2 is connected with the output end of the control power supply circuit V1, and a second end of the second resistor R2 is connected with the collector electrode of the second triode Q2.
In this embodiment, the second triode Q2 is used to control the on/off of the electronic control switch, the second resistor R2 is used to limit the collector voltage of the second triode Q2, so that the second triode Q2 enters a closed on state, when the current flowing through the electronic control switch is over-current, the base current of the second triode Q2 is increased, the collector current is also increased, the voltage on the second resistor R2 is increased accordingly, so that the collector voltage is reduced, and finally is smaller than the base voltage, the second triode Q2 enters a saturated on state, at this time, the base current of the second triode Q2 can be considered to reach a threshold value, and the collector is considered to output a low-level control signal to the control end of the electronic control switch, so as to control the electronic control switch to be turned off, and realize over-current protection; when no overcurrent occurs, the base current of the second triode Q2 is smaller than the threshold value, the second resistor R2 is used as a pull-up resistor, the potential of the collector electrode is pulled up to be high level, and the collector electrode stably outputs a high-level control signal to the control end of the electric control switch, so that the electric control switch is controlled to maintain a normal conduction state.
In one embodiment, a current detection circuit includes:
the base electrode of the first triode Q1 is connected with the input end of the temperature compensation circuit, the base electrode of the first triode Q1 is in short circuit with the collector electrode, and the emitter electrode of the first triode Q1 is connected with the input end of the electric control switch;
and a first end of the first resistor R1 is connected with the output end of the control power supply circuit V1, and a second end of the first resistor R1 is connected with the collector electrode of the first triode Q1.
The base electrode of the first triode Q1 is an output end of the current detection circuit, the base electrode and the collector electrode of the first triode Q1 are in short circuit, at the moment, the first triode Q1 is equivalent to a diode, the forward conducting voltage of the diode is the conducting voltage of the first triode Q1, the output end of the electric control switch is used as a potential reference point of the self-protection circuit, the base electrode voltage of the first triode Q1 can be obtained according to the conducting voltage of the first triode Q1 and the voltage of the electric control switch, the base electrode voltage of the first triode Q1 is the voltage of the output end of the current detection circuit, when the temperature of the electric control switch rises, the internal resistance of the electric control switch rises along with the rise of the internal resistance, the voltage of the electric control switch also rises under the condition that the current flowing through the electric control switch is unchanged, the current of the output end of the electric control switch is increased, the current signal output by the electric control switch is also increased, the temperature compensation circuit outputs the current signal to the driving circuit after temperature compensation, whether the current fault occurs currently or not according to the judging result, and the current fault is judged to be turned on or off. Thus, detection of the current flowing through the electronically controlled switch can be achieved by the first transistor Q1.
The first resistor R1 is used as a pull-up resistor, and the collector and base potentials of the first triode Q1 are pulled up to be high level, so that the first triode Q1 is kept in a conducting state, and the current flowing through the electric control switch is detected in real time.
In an embodiment, the current detection circuit further comprises:
the anode of the second diode D2 is connected with the emitter of the first triode Q1, and the cathode of the second diode D2 is connected with the input end of the electric control switch;
the driving circuit further includes:
and the anode of the third diode D3 is connected with the emitter of the second triode Q2, and the cathode of the third diode D3 is connected with the output end of the electric control switch.
The second diode D3 is used for receiving the high voltage of the power input terminal P1 instead of the first triode Q1 when the electronic control switch is turned off.
Specifically, the second diode D2 is used as a unidirectional current conducting device, and is normally conducted when the anode voltage is higher than the cathode voltage, so as to ensure the normal use of the current detection circuit, and is cut off when the cathode voltage is higher than the anode voltage, so that the second diode replaces the first triode Q1 to withstand voltage, thereby avoiding the breakdown of the first triode Q1 due to the overlarge reverse voltage, and effectively avoiding the damage of the first triode Q1.
The driving circuit and the current detection circuit adopt a second diode D2 and a third diode D3 which are arranged in pairs, and the voltage drop of the second diode D2 to the current detection circuit and the voltage drop of the third diode D3 to the driving circuit are mutually counteracted, so that the influence of the internal resistance change of the electric control switch can be counteracted only through the design parameters of the temperature compensation circuit, and the accuracy of overcurrent detection can be further improved.
In one embodiment, the current detection circuit further comprises:
the first diode D1, the positive pole of first diode D1 with the projecting pole of first triode Q1 is connected, the negative pole of first diode D1 with the collecting electrode of first triode Q1 is connected.
The first diode D1 is used as a unidirectional conduction device, so that peak current generated when the first triode Q1 and the second diode D2 are turned off flows through the first diode D1, and thus the peak current generated by the first triode Q1 and the second diode D2 is absorbed, and the device damage caused by the peak current is avoided.
In order to better illustrate the inventive concept, the working principle of the present utility model is described below with reference to specific embodiments and schematic circuit diagrams of the self-protection circuit.
Referring to fig. 2, fig. 2 is a schematic circuit structure of an embodiment of the self-protection circuit, an output end of an electric control switch is used as a potential reference point of the self-protection circuit, the electric control switch adopts a MOS transistor Q3, the MOS transistor Q3 is an N-type MOS transistor, when the current flowing through the MOS transistor Q3 does not have overcurrent, the voltage of the first transistor Q1 is increased due to the temperature rise of the MOS transistor Q3, the current flowing through the MOS transistor Q3 is constant, the voltage of the MOS transistor Q3 increases, the collector and the base of the first transistor Q1 are shorted, the first transistor Q1 is equivalent to a diode, the first resistor R1 pulls up the base and the collector of the first transistor Q1 to a high level, the base voltage of the first transistor Q1 increases along with the voltage rise of the MOS transistor Q3, the current signal flowing to the thermistor RT1 also increases along with the current, the base voltage of the first transistor Q1 passes through the thermistor RT1 and the voltage dividing resistor R3, the voltage of the second transistor Q2 is obtained, the thermistor RT1 is a positive temperature coefficient, the voltage coefficient of the thermistor RT 2 increases along with the temperature rise, the base voltage of the second transistor Q2 is not reached to the second transistor Q2, the second transistor Q2 is not reached, the second transistor Q2 is kept in a high-level state, the second transistor Q2 is not reached, and the second transistor Q2 is kept in a high-level state, and the second transistor Q2 is kept in a high state, and the second transistor Q2 is in a high state; when the current flowing through the MOS transistor Q3 flows excessively, the base current of the second triode Q2 is further increased to a threshold value, the voltage between the base and the emitter of the second triode Q2 reaches the conducting voltage of the second triode Q2, the second triode Q2 is conducted, the collector of the second triode Q2 outputs a low level, the grid electrode of the MOS transistor Q3 is low level, and the MOS transistor Q3 is switched to be in an off state, so that overcurrent protection is realized. Therefore, the situation that the current flowing through the MOS tube Q3 is turned off by mistake when the actual maximum current is not reached is avoided, the self-protection circuit can not be influenced by the temperature change of the MOS tube Q3, the current protection point of the self-protection circuit can be still maintained to be stable when the working temperature of the MOS tube Q3 changes, and the working precision of the self-protection circuit is improved.
The application also provides a pre-charging circuit, which is applied to a direct current system.
Referring to fig. 4, the precharge circuit includes a precharge resistor R4, a precharge capacitor C1, and a self-protection circuit as described above; wherein,
one end of the pre-charge resistor R4 is connected with the input end of the electric control switch of the self-protection circuit, and the other end of the pre-charge resistor R4 is connected with the output end of the electric control switch;
one end of the precharge capacitor C1 is connected with the input end of the electric control switch, and the other end of the precharge capacitor C1 is grounded.
The direct current power supply outputs larger current at the power-on stage, namely the current flowing through the electric control switch is larger, the control circuit of the self-protection circuit controls the electric control switch to be turned off after detecting the large current, the direct current power supply charges the pre-charge capacitor C1 through the pre-charge resistor R4, so that the voltage of the pre-charge capacitor C1 rises, when the voltage of the pre-charge capacitor C1 approaches to the input voltage, the electric control switch is closed, the voltage of the power output end P2 is increased due to the fact that the pre-charge capacitor C1 pulls up the voltage of the power output end P2, the electric control switch is controlled to be turned on at the moment, the direct current power supply supplies power to a load normally, and the self-protection circuit has the characteristic of stabilizing a current protection point, so that the direct current power supply can still be maintained to supply power to the load normally when the working temperature of the electric control switch changes and no overcurrent occurs.
The application also provides a direct current system.
The direct current system comprises power supply equipment and electric equipment, the direct current system further comprises the self-protection circuit or the pre-charging circuit, and the power supply equipment is connected with the electric equipment through the self-protection circuit or the pre-charging circuit.
The specific structure of the self-protection circuit or the pre-charging circuit refers to the above embodiments, and since the dc system adopts all the technical solutions of all the embodiments, at least the technical solutions of the embodiments have all the beneficial effects, and are not described in detail herein.
The foregoing is merely a specific embodiment of the present application, and any person skilled in the art may easily think of changes or substitutions within the technical scope of the present application, and should be covered in the protection scope of the present application. The protection scope of the present application shall be subject to the protection scope of the claims.
Claims (12)
1. A self-protection circuit with temperature compensation, comprising:
the electric control switch is provided with an internal resistance, and the input end of the electric control switch is used for being connected with a direct current power supply;
the current detection circuit is connected with the input end of the electric control switch and is used for detecting the current flowing through the electric control switch and outputting a current signal according to the current;
The input end of the control circuit is connected with the output end of the current detection circuit, the output end of the control circuit is connected with the control end of the electric control switch, the control circuit is used for collecting the temperature of the electric control switch, carrying out temperature compensation on the current signal according to the temperature so as to obtain a temperature compensation current signal, and driving the electric control switch to be turned off when the temperature compensation current signal reaches a threshold value.
2. The self-protection circuit of claim 1, further comprising:
the output end of the switching circuit is connected with the control end of the electric control switch or the input end of the control circuit, and the switching circuit is used for outputting a turn-off signal to the electric control switch or the control circuit when receiving a command signal so as to turn off the electric control switch.
3. The self-protection circuit of claim 1, wherein the control circuit comprises:
the input end of the temperature compensation circuit is connected with the output end of the current detection circuit, and the temperature compensation circuit is used for collecting the temperature of the electric control switch and outputting the temperature compensation current signal according to the temperature and the current signal;
The input end of the driving circuit is connected with the output end of the temperature compensation circuit, the output end of the driving circuit is connected with the control end of the electric control switch, and the driving circuit is used for driving the electric control switch to be turned off when the temperature compensation current signal reaches the threshold value.
4. The self-protection circuit of claim 3, wherein the temperature compensation circuit comprises:
the thermistor is a positive temperature coefficient thermistor, a first end of the thermistor is connected with the output end of the current detection circuit, and a second end of the thermistor is connected with the input end of the driving circuit;
and the first end of the divider resistor is connected with the public end of the thermistor and the driving circuit, and the second end of the divider resistor is connected with the output end of the electric control switch.
5. The self-protection circuit of claim 3, wherein the temperature compensation circuit comprises:
the first end of the divider resistor is connected with the output end of the current detection circuit, and the second end of the divider resistor is connected with the input end of the driving circuit;
The thermistor is a negative temperature coefficient thermistor, a first end of the thermistor is connected with a public end of the voltage dividing resistor and the driving circuit, and a second end of the thermistor is connected with an output end of the electric control switch.
6. The self-protection circuit of claim 3, wherein the drive circuit comprises:
the base of the second triode is connected with the output end of the temperature compensation circuit, the collector of the second triode is connected with the control end of the electric control switch, the emitter of the second triode is connected with the output end of the electric control switch, and the second triode is used for controlling the electric control switch to be turned on/off.
7. The self-protection circuit of claim 6, further comprising:
a control power supply circuit for supplying power to the drive circuit and the current detection circuit;
the driving circuit further includes:
and the first end of the second resistor is connected with the output end of the control power supply circuit, and the second end of the second resistor is connected with the collector electrode of the second triode.
8. The self-protection circuit of claim 7, wherein the current detection circuit comprises:
the base electrode of the first triode is connected with the input end of the temperature compensation circuit, the base electrode of the first triode is in short circuit with the collector electrode of the first triode, and the emitting electrode of the first triode is connected with the input end of the electric control switch;
and the first end of the first resistor is connected with the output end of the control power supply circuit, and the second end of the first resistor is connected with the collector electrode of the first triode.
9. The self-protection circuit of claim 8, wherein the current detection circuit further comprises:
the anode of the second diode is connected with the emitter of the first triode, and the cathode of the second diode is connected with the input end of the electric control switch;
the driving circuit further includes:
and the anode of the third diode is connected with the emitter of the second triode, and the cathode of the third diode is connected with the output end of the electric control switch.
10. The self-protection circuit of claim 8, wherein the current detection circuit further comprises:
The anode of the first diode is connected with the emitter of the first triode, and the cathode of the first diode is connected with the collector of the first triode.
11. A pre-charge circuit comprising a pre-charge resistor, a pre-charge capacitor and a self-protection circuit according to any one of claims 1 to 10; wherein,
one end of the pre-charging resistor is connected with the input end of the electric control switch of the self-protection circuit, and the other end of the pre-charging resistor is connected with the output end of the electric control switch;
one end of the pre-charge capacitor is connected with the input end of the electric control switch, and the other end of the pre-charge capacitor is grounded.
12. A direct current system, characterized by comprising a power supply device and a consumer, the direct current system further comprising a self-protection circuit as claimed in any one of claims 1 to 10 or a pre-charging circuit as claimed in claim 11, the power supply device being connected to the consumer through the self-protection circuit or the pre-charging circuit.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202321784656.8U CN220209947U (en) | 2023-07-07 | 2023-07-07 | Self-protection circuit with temperature compensation, pre-charging circuit and direct current system |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202321784656.8U CN220209947U (en) | 2023-07-07 | 2023-07-07 | Self-protection circuit with temperature compensation, pre-charging circuit and direct current system |
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| Publication Number | Publication Date |
|---|---|
| CN220209947U true CN220209947U (en) | 2023-12-19 |
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| CN202321784656.8U Active CN220209947U (en) | 2023-07-07 | 2023-07-07 | Self-protection circuit with temperature compensation, pre-charging circuit and direct current system |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN117791530A (en) * | 2023-12-28 | 2024-03-29 | 山东航天电子技术研究所 | Overcurrent automatic protector circuit with temperature compensation function |
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2023
- 2023-07-07 CN CN202321784656.8U patent/CN220209947U/en active Active
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN117791530A (en) * | 2023-12-28 | 2024-03-29 | 山东航天电子技术研究所 | Overcurrent automatic protector circuit with temperature compensation function |
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