CN221202142U - Pre-charging circuit for automatic protection of power resistor - Google Patents
Pre-charging circuit for automatic protection of power resistor Download PDFInfo
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- CN221202142U CN221202142U CN202322949571.7U CN202322949571U CN221202142U CN 221202142 U CN221202142 U CN 221202142U CN 202322949571 U CN202322949571 U CN 202322949571U CN 221202142 U CN221202142 U CN 221202142U
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Abstract
The utility model discloses a precharge circuit for automatically protecting a power resistor, which comprises an input voltage circuit, a relay circuit, a buffer circuit, an MCU detection circuit and an output voltage circuit, wherein one end of the relay circuit is connected with the positive input end of the input voltage circuit, the other end of the relay circuit is connected with the positive output end of the output voltage circuit, the buffer circuit comprises an output capacitance circuit, an IGBT and a precharge resistor, two ends of the output capacitance circuit are respectively connected with the positive output end and the negative output end of the output voltage circuit, and the IGBT and the precharge resistor which are connected in series are connected in parallel with two ends of the relay circuit; one end of the MCU detection circuit is connected with the input voltage circuit, and the other end of the MCU detection circuit is connected with the output capacitance circuit and used for detecting the voltage difference between the input voltage and the output capacitance. The utility model can be applied to high-voltage input equipment, and the precharge circuit can reduce the damage of surge current and surge voltage to a load; under the conditions of not changing the type of the relay and reducing the production cost, the service life of the relay can be prolonged and the volume of the relay can be reduced.
Description
Technical Field
The utility model relates to the technical field of precharge circuits, in particular to a precharge circuit with automatic protection of a power resistor.
Background
In the new energy automobile driving system, a power battery is connected with a motor controller, a large capacitor is arranged in the motor controller, and the capacitor is charged in the initial stage of power-up. The capacitor is an energy storage element, and when the circuit is closed, if the capacitor is not fully charged with energy, the charging current of the capacitor in the circuit can be very large. Without limitation, the large current will cause great impact to power supply, rectification and other components, and may damage related components, thereby causing faults. Therefore, the electric automobile power supply system needs to be added with the precharge circuit, reduces the impact current during power-on, prevents devices such as a motor controller, a main relay and the like from being damaged due to the impact of instantaneous large current, and can protect equipment.
The pre-charging resistor is a resistor for slowly charging the capacitor in the initial stage of high-voltage power-on of the whole equipment, and if the pre-charging resistor is not used, the capacitor can be broken down due to overlarge charging current. The high voltage is directly applied to the capacitor, which is equivalent to an instant short circuit, and the excessive short circuit current damages the high voltage electric element, so that after the capacitive load in the circuit is full, the charging circuit is turned on again, and the charging current passes through the relay and does not pass through the pre-charging resistor. Therefore, the circuit safety is ensured by the pre-charge resistor when designing the loop. Along with development of electronic technology, the types of pre-charging resistors in the pre-charging circuit are more and more, and the types of pre-charging resistors include aluminum shell resistors (also called gold resistors), thermistors (PTC resistors), power resistors and cement resistors (ceramic resistors), and aluminum shell resistors are commonly used at present.
With the development of new energy, the requirements on pre-charging and power generation are higher and higher, so how to reduce the loss of the pre-charging circuit and improve the efficiency of the pre-charging circuit becomes a current research hot spot and a current difficulty. The existing precharge circuit has the following drawbacks:
1. Under the high-voltage condition, a high-voltage-resistant relay is required to be used in the pre-charging circuit, and the high-voltage-resistant relay is often larger in size, so that pre-charging equipment wastes a certain space, and the cost is increased;
2. When the current and the voltage are high to a certain degree in the pre-charging circuit, the contact points generate sparks when the relay is attracted, and if the sparks occur when the relay works, the safety and the service life of the relay are affected;
3. In the case of using a thermistor, a ceramic resistor, an aluminum case resistor, or the like in the precharge circuit, the resistance cannot be 0 as the temperature gradually increases, and therefore, the application of only a low voltage is limited, and if other resistors are used, the cost of the product increases.
Disclosure of utility model
The utility model aims to overcome at least one defect (deficiency) of the prior art, and provides a pre-charging circuit with automatic protection of a power resistor, which is used for solving the problems of short service life, large volume and high required cost of the relay of the prior pre-charging circuit.
The technical scheme adopted by the utility model is that the precharge circuit for automatically protecting the power resistor comprises an input voltage circuit, a relay circuit, a buffer circuit, an MCU detection circuit and an output voltage circuit, wherein one end of the relay circuit is connected with the positive input end of the input voltage circuit, the other end of the relay circuit is connected with the positive output end of the output voltage circuit, the buffer circuit comprises an output capacitance circuit, an IGBT and a precharge resistor, two ends of the output capacitance circuit are respectively connected with the positive output end and the negative output end of the output voltage circuit, and the IGBT and the precharge resistor which are connected in series are connected in parallel with the two ends of the relay circuit; one end of the MCU detection circuit is connected with the input voltage circuit, and the other end of the MCU detection circuit is connected with the output capacitance circuit and used for detecting the voltage difference between the input voltage and the output capacitance.
The IGBT connected with the relay circuit in parallel is equivalent to a switch, and plays a role in turning off the control circuit in the pre-charging process. The pre-charge resistor is used for limiting current and protecting a circuit. The output capacitor circuit is used for storing electric energy in the pre-charging process. The current of the input voltage circuit charges the output capacitance circuit through the IGBT, and the voltage at two ends of the output capacitance circuit gradually rises along with the progress of the pre-charging process. The MCU detection circuit detects the voltage of the input voltage and the voltage of the output capacitor, when the difference between the voltage of the input voltage and the voltage of the output capacitor is smaller than a set value, the relay circuit is conducted, at the moment, current flows through the relay circuit and does not pass through the pre-charge resistor any more, the IGBT is disconnected, and the pre-charge process is completed.
The technical scheme can be applied to high-voltage input equipment, and the pre-charging circuit can protect a load and reduce damage of surge current and surge voltage to the load; the pre-charging circuit is connected with the IGBT and the resistor in parallel to solve the problems that the service life of the relay is short and the relay with larger volume is required to work normally under the high-voltage condition, and the service life of the low-voltage relay can be greatly prolonged and the volume of the relay can be reduced under the conditions of not changing the type of the relay and reducing the production cost.
Further, the buffer circuit further comprises a diode, wherein the diode, the IGBT and the precharge resistor are sequentially connected in series and connected in parallel to two ends of the relay circuit, and the diode is arranged between the positive input end of the input voltage circuit and the IGBT. When the positive electrode and the negative electrode of the input voltage are reversely connected, the circuit is broken due to the unidirectional conductivity of the diode, so that the circuit cannot be broken down by the reversely connected instant high voltage, and the circuit protection function is realized.
Further, the relay circuit comprises two first relays and two second relays connected in parallel.
Further, the output capacitance circuit comprises two first capacitances and two second capacitances connected in parallel.
Further, the precharge circuit further comprises a third capacitor and a common-mode inductor, two ends of the third capacitor are respectively connected with the positive input end and the negative input end of the input voltage circuit, two ends of the common-mode inductor are respectively connected with the positive input end and the negative input end of the input voltage circuit, and the positive input end of the input voltage circuit is sequentially connected with the third capacitor, the common-mode inductor and the relay circuit. The common mode inductance is used for filtering.
Further, the precharge circuit further comprises a current detection circuit which is connected in series between the common mode inductor and the output capacitor circuit, and the MCU detection circuit is connected with the current detection circuit.
Further, the current detection circuit includes a detection resistor.
Further, the MCU detection circuit is provided with a communication module.
Further, the MCU detection circuit is provided with an optocoupler operation control module.
Further, the MCU detection circuit is provided with an optocoupler output control module.
Compared with the prior art, the utility model has the beneficial effects that:
The precharge circuit design of the utility model greatly improves the service life of the relay and reduces the voltage withstand requirement of the high-voltage power supply to the relay; because the pre-charging circuit is a typical RC series circuit, the pre-charging current is large at the moment of power-on, the damage to the load in the circuit is easy to occur, the pre-charging resistance can reduce the moment of current, the IGBT is added before the pre-charging resistance, the circuit can be disconnected at any time in the pre-charging process, and the safety and the reliability of the pre-charging circuit are improved; under the conditions of not changing the type of the relay and reducing the production cost, the service life of the low-voltage relay can be greatly prolonged and the volume of the relay can be reduced.
Drawings
Fig. 1 is a circuit block diagram of the present utility model.
Fig. 2 is a schematic circuit structure of the present utility model.
Detailed Description
The drawings are for illustrative purposes only and are not to be construed as limiting the utility model. For better illustration of the following embodiments, some parts of the drawings may be omitted, enlarged or reduced, and do not represent the actual product dimensions; it will be appreciated by those skilled in the art that certain well-known structures in the drawings and descriptions thereof may be omitted.
Example 1
As shown in fig. 1 and 2, the present embodiment is a precharge circuit with automatic protection of a power resistor, which includes an input voltage circuit, a relay circuit, a buffer circuit, an MCU detection circuit and an output voltage circuit, wherein one end of the relay circuit is connected with a positive input terminal vin+ of the input voltage circuit, the other end is connected with a positive output terminal vout+ of the output voltage circuit, the buffer circuit includes an output capacitor circuit, an IGBT and a precharge resistor R1, two ends of the output capacitor circuit are respectively connected with a positive output terminal vout+ and a negative output terminal VOUT-, and the IGBT and the precharge resistor R1 connected in series are connected in parallel with two ends of the relay circuit; one end of the MCU detection circuit is connected with the input voltage circuit, and the other end of the MCU detection circuit is connected with the output capacitance circuit and used for detecting the voltage difference between the input voltage and the output capacitance.
The IGBT connected in parallel with the relay circuit is equivalent to a switch, and plays a role in controlling the turn-off of the circuit in the pre-charging process. The pre-charge resistor R1 is used for limiting current and protecting a circuit. The output capacitor circuit is used for storing electric energy in the pre-charging process. The current of the input voltage circuit charges the output capacitance circuit through the IGBT, and the voltage at two ends of the output capacitance circuit gradually rises along with the progress of the pre-charging process. The MCU detection circuit detects the voltage of the input voltage and the voltage of the output capacitor, when the voltage difference is 20V, the relay circuit is conducted, at the moment, current flows through the relay circuit, the pre-charge resistor R1 is not needed to pass, the IGBT is disconnected, and the pre-charge process is completed.
The technical scheme can be applied to high-voltage input equipment, and the pre-charging circuit can protect loads and reduce damage of surge current and surge voltage to the loads; the problem that the service life of the relay is short and the relay with larger volume is required to work normally is solved by connecting the IGBT and the resistor in parallel in the precharge circuit, and the service life of the low-voltage relay can be greatly prolonged and the volume of the relay can be reduced under the conditions of not changing the type of the relay and reducing the production cost.
The buffer circuit further comprises a diode VD1, the IGBT and the pre-charging resistor R1 are sequentially connected in series and connected at two ends of the relay circuit in parallel, and the diode VD1 is arranged between the positive input end VIN+ of the input voltage circuit and the IGBT. When the positive electrode and the negative electrode of the input voltage are reversely connected, the circuit is broken due to the unidirectional conductivity of the diode VD1, so that the circuit cannot be broken down by the reversely connected instant high voltage, and the circuit protection function is realized.
The RELAY circuit comprises two first RELAYs RELAY1 and second RELAYs RELAY2 connected in parallel.
The output capacitance circuit comprises two parallel first capacitances C1 and second capacitances C2.
The precharge circuit further comprises a third capacitor C3 and a common-mode inductor L1, wherein two ends of the third capacitor C3 are respectively connected with a positive input end VIN+ and a negative input end VIN-of the input voltage circuit, two ends of the common-mode inductor L1 are respectively connected with the positive input end VIN+ and the negative input end VIN-of the input voltage circuit, and the positive input end VIN+ of the input voltage circuit is sequentially connected with the third capacitor C3, the common-mode inductor L1 and the relay circuit. The common mode inductance L1 is used for filtering.
The precharge circuit further comprises a current detection circuit which is connected in series between the common-mode inductor L1 and the output capacitor circuit, and the MCU detection circuit is connected with the current detection circuit which comprises a detection resistor R2.
The MCU detection circuit comprises an MCU, a communication module connected with the MCU, an optocoupler operation control module and an optocoupler output control module.
It should be understood that the foregoing examples of the present utility model are merely illustrative of the present utility model and are not intended to limit the present utility model to the specific embodiments thereof. Any modification, equivalent replacement, improvement, etc. that comes within the spirit and principle of the claims of the present utility model should be included in the protection scope of the claims of the present utility model.
Claims (10)
1. The precharge circuit is characterized in that the buffer circuit comprises an output capacitance circuit, an IGBT and a precharge resistor, two ends of the output capacitance circuit are respectively connected with a positive output end and a negative output end of the output voltage circuit, and the IGBT and the precharge resistor which are connected in series are connected in parallel at two ends of the relay circuit; one end of the MCU detection circuit is connected with the input voltage circuit, and the other end of the MCU detection circuit is connected with the output capacitance circuit and used for detecting the voltage difference between the input voltage and the output capacitance.
2. The automatic power resistor protection precharge circuit of claim 1, wherein the buffer circuit further comprises a diode, the IGBT and the precharge resistor are sequentially connected in series and in parallel across the relay circuit, the diode being disposed between the positive input of the input voltage circuit and the IGBT.
3. The automatic power resistor protection precharge circuit of claim 1 wherein the relay circuit comprises two first and second relays connected in parallel.
4. The automatic power resistor protection precharge circuit of claim 1 wherein said output capacitor circuit comprises two first and second capacitors connected in parallel.
5. The automatic power resistor protection precharge circuit according to claim 1, further comprising a third capacitor and a common-mode inductor, wherein two ends of the third capacitor are respectively connected with the positive input end and the negative input end of the input voltage circuit, two ends of the common-mode inductor are respectively connected with the positive input end and the negative input end of the input voltage circuit, and the positive input end of the input voltage circuit is sequentially connected with the third capacitor, the common-mode inductor and the relay circuit.
6. The automatic power resistor protection precharge circuit of claim 5 further comprising a current sense circuit connected in series between the common mode inductor and the output capacitor circuit, the MCU sense circuit being connected to the current sense circuit.
7. The auto-protected precharge circuit of claim 6 wherein said current sense circuit comprises a sense resistor.
8. The automatic power resistor protection precharge circuit according to any one of claims 1-7, wherein the MCU detection circuit is provided with a communication module.
9. The automatic power resistor protection precharge circuit according to any one of claims 1-7, wherein the MCU detection circuit is provided with an optocoupler operation control module.
10. The automatic power resistor protection precharge circuit according to any one of claims 1-7, wherein the MCU detection circuit is provided with an optocoupler output control module.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202322949571.7U CN221202142U (en) | 2023-10-31 | 2023-10-31 | Pre-charging circuit for automatic protection of power resistor |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202322949571.7U CN221202142U (en) | 2023-10-31 | 2023-10-31 | Pre-charging circuit for automatic protection of power resistor |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN221202142U true CN221202142U (en) | 2024-06-21 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202322949571.7U Active CN221202142U (en) | 2023-10-31 | 2023-10-31 | Pre-charging circuit for automatic protection of power resistor |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN221202142U (en) |
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2023
- 2023-10-31 CN CN202322949571.7U patent/CN221202142U/en active Active
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