A pre-charge protection circuit

Abstract

The utility model discloses a kind of pre-charging protection circuits, pre-charging circuit includes pre-charging resistance and electronic switch in series, the drive input end of electronic switch is connected protection logic processing circuit;Wherein, protection logic processing circuit includes the temperature sensor for collecting pre-charging resistance temperature and comparator, temperature sensor and voltage division resistance are connected in series and are accessed after voltage division the input end of comparator, another input end of this comparator accesses preset reference voltage, its output end is connected with the drive input end of electronic switch, based on the selective conduction of electronic switch to realization to the temperature change of pre-charging resistance;The utility model proposes pre-charging circuit with protection logic processing circuit, when implementing, protection logic processing circuit based on the selective conduction of electronic switch to realization to the temperature change of pre-charging resistance, avoid the pre-charging circuit burnout condition caused by pre-charging circuit short circuit or failure, and the simple component adopted, easily promote implementation application.

Description

Technical Field

[0001] This utility model belongs to the field of electronic control structure, specifically relating to a pre-charge protection circuit. Background Technology

[0002] In new energy vehicles or energy storage systems, the presence of large-capacity capacitors in the electronic control system leads to a large current surge when the system is powered on. This large current poses a risk of blowing fuses or causing the system to trip. To mitigate this risk, pre-charging circuits, mainly composed of pre-charging resistors and relays, are currently used to pre-charge the large-capacity capacitors. However, due to issues with pre-charging control and the coordination logic between the upper and lower level computers, or subsequent faults, the pre-charging circuit often burns out.

[0003] Therefore, the applicant seeks a technical solution to resolve the technical problem. Summary of the Invention

[0004] In view of this, the purpose of this utility model is to propose a pre-charge protection circuit, which proposes a pre-charge circuit with a protection logic processing circuit. In implementation, the protection logic processing circuit selectively turns on the electronic switch based on the temperature change of the pre-charge resistor, so as to avoid the pre-charge circuit burning out due to short circuit or failure. Moreover, the components used are simple and easy to promote and implement.

[0005] The technical solution adopted in this utility model is as follows: A pre-charge protection circuit includes a capacitor and a relay disposed at the positive terminal of a power input, with a pre-charge circuit connected in parallel across the two ends of the relay. The pre-charge circuit includes a pre-charge resistor and an electronic switch connected in series, with the drive input terminal of the electronic switch connected to a protection logic processing circuit. The protection logic processing circuit includes a temperature sensor for acquiring the temperature of the pre-charge resistor and a comparator. The temperature sensor is connected in series with a voltage divider resistor for voltage division and then connected to one input terminal of the comparator. The other input terminal of the comparator is connected to a preset reference voltage, and its output terminal is connected to the drive input terminal of the electronic switch. The selective conduction of the electronic switch is achieved based on the temperature change of the pre-charge resistor.

[0006] Preferably, a diode is also connected in series in the pre-charge circuit to reverse cut off when an abnormal reverse connection occurs at the positive and negative terminals of the power input, so that no current flows through the pre-charge circuit.

[0007] Preferably, the temperature sensor is an NTC resistor. The higher the temperature of the pre-charge resistor, the lower the resistance of the temperature sensor and the lower the voltage drop.

[0008] Preferably, the pre-charge resistor is a surface-mount resistor, and the temperature sensor is installed near the pre-charge resistor to collect the temperature of the pre-charge resistor.

[0009] Preferably, the temperature sensor is connected in series with a voltage divider resistor to divide the voltage and then connected to the positive input terminal of the comparator; the preset reference voltage is connected to the negative input terminal of the comparator; wherein, when the voltage at the positive input terminal is higher than the voltage at the negative input terminal, the comparator outputs a high level, causing the electronic switch to remain on; when a short circuit or other fault occurs in the pre-charge circuit, the current flowing through the pre-charge resistor increases, heat accumulates, the temperature continues to rise, the resistance of the temperature sensor decreases until the voltage at the positive input terminal is lower than the voltage at the negative input terminal, the comparator outputs a low level, causing the electronic switch to be turned off, cutting off the pre-charge circuit.

[0010] Preferably, the preset reference voltage is formed by a reference voltage divider circuit; wherein the reference voltage divider circuit includes at least a first reference voltage divider resistor and a second reference voltage divider resistor connected in series, wherein one reference voltage divider resistor is connected to a reference power supply, and the other reference voltage divider resistor is grounded or connected to a reference voltage.

[0011] Preferably, the comparator further includes a hysteresis circuit; wherein the hysteresis circuit includes a hysteresis resistor disposed between the comparator input terminal and the comparator output terminal corresponding to the temperature sensor; when the protection logic processing circuit oscillates back and forth near the over-temperature point of the pre-charge resistor to conduct and turn off, the voltage threshold of the comparator input terminal corresponding to the temperature sensor is reduced through the hysteresis resistor, so that the electronic switch is turned off and the pre-charge circuit is cut off.

[0012] Preferably, the electronic switch is an IGBT or a MOSFET.

[0013] Preferably, a first resistor and a second resistor are connected to the connection circuit between the output terminal of the comparator and the drive input terminal of the electronic switch, respectively; wherein, the other end of the first resistor is connected to the power supply, the other end of the second resistor is connected to the output terminal of the electronic switch, and the other end of the connection point is grounded or connected to a reference voltage.

[0014] Preferably, a capacitor is connected between the temperature sensor and the input terminal of its corresponding comparator, and the other end of the capacitor is grounded or connected to a reference voltage.

[0015] This invention proposes a pre-charge circuit with a protection logic processing circuit, mainly composed of a temperature sensor for collecting the temperature of the pre-charge resistor and a comparator. The temperature sensor is connected in series with a voltage divider resistor to divide the voltage and then connected to one input terminal of the comparator. The other input terminal of the comparator is connected to a preset reference voltage, and its output terminal is connected to the drive input terminal of the electronic switch. In implementation, the protection logic processing circuit selectively turns on the electronic switch based on the temperature change of the pre-charge resistor, avoiding the pre-charge circuit from burning out due to short circuit or failure. Moreover, the components used are simple and easy to promote and implement. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the switch state detection circuit according to a specific embodiment of this utility model. Detailed Implementation

[0017] This utility model discloses a pre-charge protection circuit, including a capacitor and a relay disposed at the positive terminal of the power input, with a pre-charge circuit connected in parallel across the two ends of the relay; the pre-charge circuit includes a pre-charge resistor and an electronic switch connected in series, and the drive input terminal of the electronic switch is connected to a protection logic processing circuit; wherein, the protection logic processing circuit includes a temperature sensor for acquiring the temperature of the pre-charge resistor and a comparator, the temperature sensor is connected in series with a voltage divider resistor for voltage division and then connected to one input terminal of the comparator, the other input terminal of the comparator is connected to a preset reference voltage, and its output terminal is connected to the drive input terminal of the electronic switch, so as to selectively turn on the electronic switch based on the temperature change of the pre-charge resistor.

[0018] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Please see Figure 1 As shown, this embodiment proposes a pre-charge protection circuit, including a circuit configured at the positive terminal J1-1 of the power input (the negative terminal of the power input is...). Figure 1 The J2-1 shown includes capacitor C001 (the other end of capacitor C001 is grounded to PGND) and relay K1-B. A pre-charge circuit is connected in parallel across the two ends of relay K1-B. The pre-charge circuit includes a pre-charge resistor R001 connected in series and an electronic switch Q2. The drive input terminal of electronic switch Q2 is connected to a protection logic processing circuit. The protection logic processing circuit includes a temperature sensor TC01 for acquiring the temperature of the pre-charge resistor R001 and a comparator U001-A. The temperature sensor TC01 is connected in series with a voltage divider resistor R007 to divide the voltage and then connected to one input terminal of comparator U001-A. The other input terminal of comparator U001-A is connected to a preset reference voltage, and its output terminal is connected to the drive input terminal of electronic switch Q2. The selective conduction of electronic switch Q2 is achieved based on the temperature change of the pre-charge resistor R001. Preferably, electronic switch Q2 is an IGBT or MOSFET. Of course, other suitable electronic switches can also be used. This embodiment does not impose any special restrictions on this. Specifically, in this embodiment, electronic switch Q2 is an IGBT.

[0020] Preferably, in this embodiment, a diode D1 is also connected in series in the precharge circuit to reverse cut off when an abnormal reverse connection occurs at the positive and negative terminals of the power input, so that no current flows through the precharge circuit.

[0021] Preferably, in this embodiment, the temperature sensor TC01 is an NTC resistor. The higher the temperature of the pre-charge resistor R001, the smaller the resistance of the temperature sensor TC01 and the smaller the voltage drop value. Preferably, in this embodiment, the pre-charge resistor R001 is a surface-mount resistor, and the temperature sensor TC01 is installed near the pre-charge resistor R001 to collect the temperature of the pre-charge resistor R001.

[0022] More preferably, in this embodiment, the temperature sensor TC01 is connected in series with the voltage divider resistor R007 to perform voltage division, and then connected to the positive input terminal of the comparator U001-A (e.g., Figure 1 As shown, the other end of the voltage divider resistor R007 is connected to a +15V power supply, and the other end of the temperature sensor TC01 is grounded or connected to a reference voltage REF. The preset reference voltage is connected to the negative input of comparator U001-A. During the normal pre-charge cycle, the pre-charge resistor R001 has a lower temperature; therefore, the voltage at the temperature sensor TC01 (i.e., the positive input voltage) will be higher than the negative input voltage of comparator U001-A, causing comparator U001-A to output a high level, keeping electronic switch Q2 continuously on. When a short circuit or other fault occurs in the pre-charge circuit... When the relay K1-B fails to meet the activation condition, the current flowing through the pre-charge resistor R001 increases, heat accumulates, and the temperature continues to rise. The resistance of the temperature sensor TC01 decreases as the temperature of the pre-charge resistor R001 rises, and consequently, the voltage across it also decreases. When the temperature of the pre-charge resistor R001 reaches the set threshold, the voltage at the temperature sensor TC01 (i.e., the positive input voltage) will be lower than the negative input voltage of the comparator U001-A. At this time, the comparator U001-A outputs a low level, causing the electronic switch Q2 to be turned off, thus cutting off the pre-charge circuit.

[0023] Preferably, in this embodiment, the preset reference voltage is formed by a reference voltage divider circuit; wherein, the reference voltage divider circuit includes at least a first reference voltage divider resistor R005 and a second reference voltage divider resistor R006 connected in series, one of the reference voltage divider resistors is connected to the reference power supply, and the other reference voltage divider resistor is grounded or connected to the reference voltage REF.

[0024] Considering that during implementation, the actual temperature of the pre-charge resistor R001 oscillates around its temperature protection threshold, the protection logic processing circuit proposed in this embodiment may cause the electronic switch Q2 to oscillate back and forth during conduction and de-conduction (i.e., when the protection logic processing circuit oscillates back and forth around the over-temperature point of the pre-charge resistor R001 during conduction and de-conduction as described herein). To avoid this problem, preferably, in this embodiment, the comparator U001-A is also provided with a hysteresis circuit; wherein, the hysteresis circuit includes a hysteresis resistor R004 disposed between the input terminal and the output terminal of the comparator U001-A corresponding to the temperature sensor TC01; when the protection logic processing circuit oscillates back and forth around the over-temperature point of the pre-charge resistor R001 during conduction and de-conduction, the voltage threshold of the input terminal of the comparator U001-A corresponding to the temperature sensor TC01 is reduced through the hysteresis resistor R004, so that the electronic switch Q2 is turned off, cutting off the pre-charge circuit.

[0025] Preferably, in this embodiment, a first resistor R002 and a second resistor R003 are connected to the connection circuit between the output terminal of comparator U001-A and the drive input terminal of electronic switch Q2, respectively; wherein, the other end of the first resistor R002 is connected to the power supply, and the other end of the second resistor R003 is connected to the output terminal of electronic switch Q2, and the other end of this connection point is grounded or connected to the reference voltage REF; it should be noted that the first resistor R002 is a pull-up resistor, which has a current limiting function. Since comparator U001-A is an open-drain output, when the voltage at its input terminal 3 (i.e., the positive input terminal) is higher than the voltage at its input terminal 1 (i.e., the negative input terminal), the first resistor R002 pulls up the output of comparator U001-A to +15V, that is, the gate input of electronic switch IGBT Q2 becomes +15V, and electronic switch IGBT... When Q2 is turned on, and the voltage at its input terminal 3 (i.e., the positive input terminal) is lower than the voltage at its input terminal 1 (i.e., the negative input terminal), the comparator U001-A outputs a low level. The first resistor R002 limits the current to prevent the comparator from burning out due to excessive output current. The second resistor R003 is a pull-down resistor for the gate terminal (i.e., the drive input terminal) of the electronic switch IGBT Q2, providing a stable level to the gate terminal of the electronic switch IGBT Q2 and enhancing its anti-interference capability.

[0026] Preferably, in this embodiment, a filter capacitor C002 is connected between the temperature sensor TC01 and the input terminal of its corresponding comparator U001-A, and the other end of the filter capacitor C002 is grounded or connected to the reference voltage REF. The filter capacitor C002 is used to prevent voltage fluctuations at the corresponding input pin of the comparator U001-A due to interference.

[0027] It should be noted that the "grounding or connection reference voltage REF" involved in this application, such as Figure 1 As shown, this specific embodiment uses "connected reference voltage REF". In other embodiments, specific choices can be made according to actual needs. These implementation variations are common knowledge to those skilled in the art.

[0028] To further illustrate the implementation process of this embodiment, this application sets a set of specific implementation application parameters for key components, as shown in Table 1 below: .

[0029] The “temperature protection value” shown in Table 1 is the temperature protection threshold (also known as the “over-temperature point”) of the pre-charge resistor R001. The “recovery value” is the temperature recovery value of the pre-charge resistor R001 corresponding to the recovery of the electronic switch Q2. The temperature difference between the recovery value and the temperature protection value is the range near the over-temperature point of the pre-charge resistor R001. The hysteresis circuit set in this embodiment is used to avoid the problem that the electronic switch Q2 may oscillate back and forth during conduction and turn-off in the range near the over-temperature point of the pre-charge resistor R001.

[0030] It will be apparent to those skilled in the art that this invention is not limited to the details of the exemplary embodiments described above, and that it can be implemented in other specific forms without departing from the spirit or essential characteristics of this invention. Therefore, the embodiments should be considered illustrative and non-limiting in all respects, and the scope of this invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within this invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0031] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A pre-charge protection circuit, comprising a capacitor (C001) and a relay (K1-B) disposed at the positive terminal (J1-1) of a power input, wherein a pre-charge circuit is connected in parallel across the two ends of the relay (K1-B); characterized in that, The pre-charge circuit includes a pre-charge resistor (R001) and an electronic switch (Q2) connected in series. The drive input terminal of the electronic switch (Q2) is connected to a protection logic processing circuit. The protection logic processing circuit includes a temperature sensor (TC01) for acquiring the temperature of the pre-charge resistor (R001) and a comparator (U001-A). The temperature sensor (TC01) is connected in series with a voltage divider resistor (R007) to divide the voltage and then connected to one input terminal of the comparator (U001-A). The other input terminal of the comparator (U001-A) is connected to a preset reference voltage, and its output terminal is connected to the drive input terminal of the electronic switch (Q2). The selective conduction of the electronic switch (Q2) is achieved based on the temperature change of the pre-charge resistor (R001).

2. The pre-charge protection circuit according to claim 1, characterized in that, A diode (D1) is also connected in series in the precharge circuit to reverse cut off the circuit when there is an abnormal reverse connection between the positive and negative terminals of the power input, so that no current flows through the precharge circuit.

3. The pre-charge protection circuit according to claim 1, characterized in that, The temperature sensor (TC01) uses an NTC resistor. The higher the temperature of the pre-charge resistor (R001), the lower the resistance of the temperature sensor (TC01) and the lower the voltage drop.

4. The pre-charge protection circuit according to claim 1 or 3, characterized in that, The pre-charge resistor (R001) is a surface-mount resistor, and the temperature sensor (TC01) is installed near the pre-charge resistor (R001) to collect the temperature of the pre-charge resistor (R001).

5. The pre-charge protection circuit according to claim 1, characterized in that, The temperature sensor (TC01) is connected in series with the voltage divider resistor (R007) to divide the voltage and then connect it to the positive input terminal of the comparator (U001-A); the preset reference voltage is connected to the negative input terminal of the comparator (U001-A); when the voltage at the positive input terminal is higher than the voltage at the negative input terminal, the comparator (U001-A) outputs a high level, causing the electronic switch (Q2) to remain on; when a short circuit or other fault occurs in the pre-charge circuit, the current flowing through the pre-charge resistor (R001) increases, heat accumulates, the temperature continues to rise, the resistance of the temperature sensor (TC01) decreases until the voltage at the positive input terminal is lower than the voltage at the negative input terminal, the comparator (U001-A) outputs a low level, causing the electronic switch (Q2) to be turned off, cutting off the pre-charge circuit.

6. The pre-charge protection circuit according to claim 1 or 5, characterized in that, The preset reference voltage is formed by a reference voltage divider circuit; wherein, the reference voltage divider circuit includes at least a first reference voltage divider resistor (R005) and a second reference voltage divider resistor (R006) connected in series, one of the reference voltage divider resistors is connected to the reference power supply, and the other reference voltage divider resistor is grounded or connected to the reference voltage (REF).

7. The pre-charge protection circuit according to claim 1, characterized in that, The comparator (U001-A) is also provided with a hysteresis circuit; wherein, the hysteresis circuit includes a hysteresis resistor (R004) disposed between the input terminal and the output terminal of the comparator (U001-A) corresponding to the temperature sensor (TC01); when the protection logic processing circuit oscillates back and forth near the over-temperature point of the pre-charge resistor (R001) to conduct and turn off, the voltage threshold of the input terminal of the comparator (U001-A) corresponding to the temperature sensor (TC01) is reduced through the hysteresis resistor (R004), so that the electronic switch (Q2) is turned off and the pre-charge circuit is cut off.

8. The pre-charge protection circuit according to claim 1, characterized in that, The electronic switch (Q2) is an IGBT or a MOSFET.

9. The pre-charge protection circuit according to claim 1, characterized in that, The circuit connecting the output of the comparator (U001-A) and the drive input of the electronic switch (Q2) is equipped with a first resistor (R002) and a second resistor (R003); the other end of the first resistor (R002) is connected to the power supply, and the other end of the second resistor (R003) is connected to the output of the electronic switch (Q2).

10. The pre-charge protection circuit according to claim 1, characterized in that, A filter capacitor (C002) is also connected between the temperature sensor (TC01) and the input terminal of its corresponding comparator (U001-A), and the other end of the filter capacitor (C002) is grounded or connected to a reference voltage (REF).

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