Surge suppression circuit of vehicle-mounted DC-DC converter

Abstract

The utility model provides a vehicle-mounted DC-DC converter surge suppression circuit, which is characterized in that a drain electrode of a second N-type MOS (Metal Oxide Semiconductor) tube in a pre-charging circuit is connected with a drain electrode of a first N-type MOS tube in a fast charging circuit and a positive end of an input power supply after passing through a current-limiting resistor, and source electrodes of the first and second N-type MOS tubes are connected with an input positive end of a DC-DC converter power stage; two input ends of the fast charge turn-off circuit are respectively connected with a drain electrode and a source electrode of the first N-type MOS tube, the output of the fast charge turn-off circuit is connected with the fast charge control circuit, the fast charge control circuit outputs signals to the fast charge circuit and the pre-charge turn-off circuit, and the output of the pre-charge turn-off circuit is connected with the pre-charge control circuit and then is connected to the pre-charge circuit; according to the surge suppression circuit of the vehicle-mounted DC-DC converter, when the voltage difference between the drain electrode end and the source electrode end of the first N-type MOS tube is too high, the fast charging circuit and the pre-charging circuit are turned off to work, otherwise, the pre-charging circuit and the fast charging circuit are turned off to work, the input surge current is effectively suppressed in the whole process through voltage detection and sequential control, the surge suppression circuit is safe and controllable, and the surge suppression effect is good. The reliability is high.

Description

Technical Field

[0001] This utility model relates to the field of vehicle power supply, and in particular to a surge suppression circuit for vehicle DC-DC converters. Background Technology

[0002] Currently, automotive DC-DC converters are widely used, and their functional safety is a major concern. Due to the presence of automotive input capacitors and other inductive loads, a transient high voltage will appear at the front end of the DC-DC converter at the moment of input terminal connection, and a large surge current will flow through the main circuit, causing damage to the power devices downstream of the DC-DC converter. To address this issue, existing technologies typically use a PTC resistor connected in parallel with a relay. However, relays are bulky, have poor stability, and require external power supplies and complex control circuitry. Therefore, this approach is no longer suitable for high-precision, high-reliability, and miniaturized automotive switching power supplies. Furthermore, the PTC resistor cannot prevent high voltage from entering the power stage circuitry of the subsequent DC-DC converter. A further technology uses N-type MOSFETs instead of relays, with the related driving and detection functions of the MOSFETs implemented using a microcontroller. However, microcontroller detection takes time and cannot achieve microsecond-level protection. Moreover, the microcontroller's driving capability is weak, requiring external drivers. In addition, the microcontroller itself is expensive and requires programming, increasing production time and turnaround risks. This poses a challenge in terms of cost and space for low-power automotive DC-DC converters. Therefore, a simple analog circuit is needed to solve the aforementioned surge current problem.

[0003] To address the aforementioned issues, this invention provides a surge suppression circuit for an on-board DC-DC converter. Utility Model Content

[0004] The technical problem solved by this utility model is to provide a surge suppression circuit for an on-board DC-DC converter.

[0005] The technical solution adopted by this utility model to solve the above-mentioned technical problems is: a surge suppression circuit for an on-board DC-DC converter, characterized in that the circuit includes a fast charging circuit, a fast charging control circuit, a fast charging shutdown circuit, a pre-charging circuit, a pre-charging control circuit, and a pre-charging shutdown circuit. The fast charging circuit includes a first N-type MOS transistor, the drain of which is connected to the positive terminal of the input power supply, and the source of which is connected to the positive input terminal of the DC-DC converter power stage. The two input ports of the fast charging shutdown circuit are respectively connected to the positive terminal of the input power supply and the positive input terminal of the DC-DC converter power stage. The output of the fast charging shutdown circuit is connected to one input port of the fast charging control circuit, and the fast charging control circuit outputs a PWM signal to the fast charging circuit and the pre-charging shutdown circuit. The pre-charging circuit includes a second N-type MOS transistor, the drain of which is connected to the positive terminal of the input power supply through a sixth resistor, and the source of which is connected to the positive input terminal of the DC-DC converter power stage. The output of the pre-charging shutdown circuit is connected to one input port of the pre-charging control circuit, and the pre-charging control circuit outputs a PWM signal to the pre-charging circuit.

[0006] Furthermore, the fast charging circuit also includes a first capacitor, a second capacitor, a first diode, and a second diode. The fast charging control circuit outputs a PWM signal to one end of the first capacitor. The other end of the first capacitor is connected to the anode of the first diode and the cathode of the second diode. The cathode of the first diode is connected to the gate of the first N-type MOSFET and one end of the second capacitor. The anode of the second diode is connected to the source of the first N-type MOSFET and the other end of the second capacitor.

[0007] Furthermore, the precharge circuit also includes a fifth capacitor, a sixth capacitor, a fourth diode, and a fifth diode. The precharge control circuit outputs a PWM signal to one end of the fifth capacitor. The other end of the fifth capacitor is connected to the anode of the fourth diode and the cathode of the fifth diode. The cathode of the fourth diode is connected to the gate of the second N-type MOS transistor and one end of the sixth capacitor. The anode of the fifth diode is connected to the source of the second N-type MOS transistor and the other end of the sixth capacitor.

[0008] Furthermore, the fast-charging shutdown circuit includes a third N-type MOSFET, an error amplifier, a first resistor, a second resistor, a third resistor, a fourth resistor, a fifth resistor, a third diode, a third capacitor, and a fourth capacitor. One end of the fourth resistor is connected to the positive terminal of the input power supply, and the other end is connected to the positive input terminal of the error amplifier, one end of the fifth resistor, and one end of the fourth capacitor. One end of the second resistor is connected to the positive input terminal of the DC-DC converter power stage, and the other end is connected to the negative input terminal of the error amplifier, one end of the third resistor, and one end of the third capacitor. The output of the error amplifier is connected to the anode of the third diode. The cathode of the third diode is connected to the gate of the third N-type MOSFET and one end of the first resistor. The drain of the third N-type MOSFET is connected to an input port of the fast-charging control circuit. The source of the third N-type MOSFET, the ground terminal of the error amplifier, the negative terminal of the input power supply, and the negative input terminal of the DC-DC converter power stage are grounded. The other ends of the first resistor, the third resistor, the fifth resistor, the third capacitor, and the fourth capacitor are grounded.

[0009] Furthermore, the pre-charge shutdown circuit mainly includes a sixth diode, a seventh resistor, an eighth resistor, a seventh capacitor, and a fourth N-type MOSFET. The anode of the sixth diode is connected to the output port of the fast charge control circuit, the cathode of the sixth diode is connected to one end of the seventh resistor, the other end of the seventh resistor is connected to one end of the eighth resistor, the gate of the fourth N-type MOSFET, and one end of the seventh capacitor, the drain of the fourth N-type MOSFET is connected to one input port of the signal pre-charge control circuit, and the source of the fourth N-type MOSFET, the other end of the seventh capacitor, and the eighth resistor are grounded.

[0010] Furthermore, the input power source refers to an on-board generator or an on-board high-voltage battery.

[0011] Furthermore, the pre-charge control and fast charge control circuits mainly include an error amplifier.

[0012] The technical advantages achieved by this utility model compared to existing designs are as follows:

[0013] This invention provides a surge suppression circuit for an on-board DC-DC converter. It adds two sets of parallel MOS controls between the input power supply and the DC-DC converter input terminal. One set is a pre-charge circuit, consisting of a low-power MOS, a current-limiting resistor, and related MOS drivers. The other set is a fast-charge circuit, consisting of a high-power MOS and related MOS drivers. Through voltage detection and timing control, it effectively suppresses input surge current, making the circuit safer and more controllable. It eliminates the need for a microcontroller and the steps of writing a microcontroller program, resulting in lower costs. Attached Figure Description

[0014] Figure 1This is a schematic diagram of the surge suppression circuit structure of the vehicle-mounted DC-DC converter provided by this utility model;

[0015] Figure 2 This is a schematic diagram of the pre-charge shutdown circuit in the circuit of this utility model. Detailed Implementation

[0016] The embodiments of the circuit of this utility model are given below with reference to the accompanying drawings to illustrate the technical solution of this utility model in detail.

[0017] as follows Figure 1 This utility model provides a surge suppression circuit for an on-board DC-DC converter. The circuit includes a fast charging line 10, a fast charging control line 20, a fast charging shutdown line 30, a pre-charging line 40, a pre-charging control line 50, and a pre-charging shutdown line 60. The fast charging line 10 includes a first N-type MOSFET Q1, whose drain is connected to the positive terminal VIN1 of the input power supply, and whose source is connected to the positive input terminal VIN2 of the DC-DC converter power stage. The two input ports of the fast charging shutdown line 30 are connected to VIN1 and VIN2 respectively. The output of line 30 is connected to one input port PWM1_IN+ of line 20, and line 20 outputs the signal PWM1 to line 10 and line 60. Line 40 includes a second N-type MOSFET Q2, whose drain is connected to VIN1 through a sixth resistor R6, and the source of Q2 is connected to VIN2. The output of line 60 is connected to one input port PWM0_IN+ of line 50, and line 50 outputs the signal PWM0 to line 40.

[0018] The fast charging line 10 also includes a first capacitor C1, a second capacitor C2, a first diode CR1, and a second diode CR2. The output port of the line 20 provides a PWM1 signal to one end of C1. The other end of C1 is connected to the anode of CR1 and the cathode of CR2. The cathode of CR1 is connected to the gate of Q1 and one end of C2. The anode of CR2 is connected to the source of Q1 and the other end of C2.

[0019] The precharge line 40 also includes a fifth capacitor C5, a sixth capacitor C6, a fourth diode CR4, and a fifth diode CR5. The line 50 outputs a PWM0 signal to one end of C5. The other end of C5 is connected to the anode of CR4 and the cathode of CR5. The cathode of CR4 is connected to the gate of Q2 and one end of C6. The anode of CR5 is connected to the source of Q2 and the other end of C6.

[0020] The fast-charging shutdown circuit 30 includes a third N-type MOSFET Q3, an error amplifier IC1, a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, a fifth resistor R5, a third diode CR3, a third capacitor C3, and a fourth capacitor C4. One end of R4 is connected to VIN1, and the other end is connected to the positive input terminal IN+ of IC1, one end of R5 and C4. One end of R2 is connected to VIN2, and the other end is connected to the negative input terminal IN- of IC1, one end of R3 and C3. The output of IC1 is connected to the anode of CR3. The cathode of CR3 is connected to the gate of Q3 and one end of R1. The drain of Q3 is connected to an input port PWM1_IN+ of line 20. The source of Q3, the ground terminal of IC1, the negative terminal of the input power supply, and the negative input terminal of the DC-DC converter power stage are grounded. The other ends of R1, R3, R5, C3, and C4 are grounded. The power supply terminal VBP of IC1 is a stable voltage signal generated by the internal circuitry of the DC-DC converter.

[0021] The fast charging control circuit 20 and the pre-charge control circuit 50 mainly include an error amplifier. The PWM1_IN+ signal is generated internally by the fast charging control circuit 20, and the PWM0_IN+ signal is generated internally by the pre-charge control circuit 50.

[0022] as follows Figure 2 In the circuit 60, the precharge shutdown circuit mainly includes a sixth diode CR6, a seventh resistor R7, an eighth resistor R8, a seventh capacitor C7, and a fourth N-type MOSFET Q4. The anode of CR6 is connected to the output port of circuit 20, i.e., connected to the PWM1 signal. The cathode of CR6 is connected to one end of R7. The other end of R7 is connected to one end of R8, the gate of Q4, and one end of C7. The drain of Q4 is connected to the input port of circuit 50, i.e., connected to the PWM0_IN+ signal. The other ends of C7 and R8 are grounded. When there is a PWM1 signal, PWM1 is divided by diode CR6 and resistors R7 and R8 and then sent to the gate of Q4. Q4 is turned on, PWM0_IN+ is pulled low, the precharge control circuit has no PWM0 output, and the precharge circuit does not work. Conversely, when there is no PWM1 signal, PWM0_IN+ is not pulled low, the precharge control circuit has PWM0 output, and the precharge circuit starts to work.

[0023] When the DC-DC converter is powered on, the external input power supply VIN1 supplies power to the internal circuitry, generating auxiliary power supply VBP. Because the body diodes of N-type MOSFETs Q1 and Q2 are reverse-biased, Q1 and Q2 are not conducting, and the voltage of VIN2 is 0. Since VBP has a stable voltage, IC1 operates. When VIN2 < 90% VIN1 (the specific voltage can be adjusted by the resistance values ​​of R2, R3, R4, and R5), IC1 outputs a high level. This output flows through CR3 to the gate of Q3, turning Q3 on. The PWM1_IN+ signal is pulled low, so the fast charging control circuit does not operate, and there is no PWM1 signal output. The fast charging circuit is off, and PWM0_IN+ is high. The pre-charge control circuit outputs a PWM0 signal, and the pre-charge circuit operates, charging Vgs of the pre-charge MOSFET Q2 and slowly charging the internal input voltage Cin through the current-limiting resistor R6. The charging current can be controlled by the value of the current-limiting resistor R6. If VIN2 is detected... If VIN2 is less than 90% of VIN1, it remains in pre-charge state. If VIN2 > 90% of VIN1, IC1 outputs a low level, Q3 is not turned on, and PWM1_IN+ is high. The fast charging control circuit outputs a PWM1 signal to the gate of Q1, Q1 turns on, the module's main power starts working, and current flows through the fast charging MOSFET Q1 to quickly charge the input capacitor Cin to the same voltage as VIN1. At the same time, the pre-charge shutdown circuit has a PWM1 signal input, which pulls the PWM0_IN+ signal low. Therefore, the pre-charge control circuit has no PWM0 signal, and the pre-charge circuit is turned off.

[0024] While specific embodiments of this utility model have been described above, those skilled in the art should understand that these are merely illustrative examples, and various changes or modifications can be made to these embodiments without departing from the principles and essence of this utility model. Therefore, the scope of protection of this utility model is defined by the appended claims.

Claims

1. A surge suppression circuit for an on-board DC-DC converter, characterized in that, The circuit includes a fast charging circuit, a fast charging control circuit, a fast charging shutdown circuit, a pre-charging circuit, a pre-charging control circuit, and a pre-charging shutdown circuit. The fast charging circuit includes a first N-type MOS transistor, whose drain is connected to the positive terminal of the input power supply and whose source is connected to the positive input terminal of the DC-DC converter power stage. The two input ports of the fast charging shutdown circuit are respectively connected to the positive terminal of the input power supply and the positive input terminal of the DC-DC converter power stage. The output of the fast charging shutdown circuit is connected to one input port of the fast charging control circuit. The fast charging control circuit outputs a PWM signal to the fast charging circuit and the pre-charging shutdown circuit. The precharge circuit includes a second N-type MOS transistor, whose drain is connected to the positive terminal of the input power supply through a sixth resistor, and whose source is connected to the positive input terminal of the power stage of the DC-DC converter. The output of the precharge shutdown circuit is connected to an input port of the precharge control circuit, and the precharge control circuit outputs a PWM signal to the precharge circuit.

2. The surge suppression circuit for an on-board DC-DC converter as described in claim 1, characterized in that, The fast charging circuit also includes a first capacitor, a second capacitor, a first diode, and a second diode. The fast charging control circuit outputs a PWM signal to one end of the first capacitor. The other end of the first capacitor is connected to the anode of the first diode and the cathode of the second diode. The cathode of the first diode is connected to the gate of the first N-type MOSFET and one end of the second capacitor. The anode of the second diode is connected to the source of the first N-type MOSFET and the other end of the second capacitor.

3. The surge suppression circuit for an on-board DC-DC converter as described in claim 1, characterized in that, The precharge circuit also includes a fifth capacitor, a sixth capacitor, a fourth diode, and a fifth diode. The precharge control circuit outputs a PWM signal to one end of the fifth capacitor. The other end of the fifth capacitor is connected to the anode of the fourth diode and the cathode of the fifth diode. The cathode of the fourth diode is connected to the gate of the second N-type MOS transistor and one end of the sixth capacitor. The anode of the fifth diode is connected to the source of the second N-type MOS transistor and the other end of the sixth capacitor.

4. The surge suppression circuit for an on-board DC-DC converter as described in claim 1, characterized in that, The fast-charging shutdown circuit includes a third N-type MOSFET, an error amplifier, a first resistor, a second resistor, a third resistor, a fourth resistor, a fifth resistor, a third diode, a third capacitor, and a fourth capacitor. One end of the fourth resistor is connected to the positive terminal of the input power supply, and the other end is connected to the positive input terminal of the error amplifier, one end of the fifth resistor, and one end of the fourth capacitor. One end of the second resistor is connected to the positive input terminal of the DC-DC converter power stage, and the other end is connected to the negative input terminal of the error amplifier, one end of the third resistor, and one end of the third capacitor. The output of the error amplifier is connected to the anode of the third diode. The cathode of the third diode is connected to the gate of the third N-type MOSFET and one end of the first resistor. The drain of the third N-type MOSFET is connected to an input port of the fast-charging control circuit. The source of the third N-type MOSFET, the ground terminal of the error amplifier, the negative terminal of the input power supply, and the negative input terminal of the DC-DC converter power stage are grounded. The other ends of the first, third, fifth, third, and fourth resistors are grounded.

5. A surge suppression circuit for an on-board DC-DC converter as described in claim 1, wherein the pre-charge shutdown circuit mainly comprises a sixth diode, a seventh resistor, an eighth resistor, a seventh capacitor, and a fourth N-type MOSFET. The anode of the sixth diode is connected to the output port of the fast charging control circuit, the cathode of the sixth diode is connected to one end of the seventh resistor, the other end of the seventh resistor is connected to one end of the eighth resistor, the gate of the fourth N-type MOSFET, and one end of the seventh capacitor, the drain of the fourth N-type MOSFET is connected to one input port of the pre-charge control circuit, and the source of the fourth N-type MOSFET, the other end of the seventh capacitor, and the eighth resistor are grounded.

6. A surge suppression circuit for an on-board DC-DC converter as described in claim 1, characterized in that, The input power source refers to the vehicle-mounted generator or the vehicle-mounted high-voltage battery.

7. A surge suppression circuit for an on-board DC-DC converter as described in claim 1, characterized in that, The precharge control and fast charge control circuits mainly include an error amplifier.

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