Back electromotive force absorption device and method for vehicle-mounted low-voltage power supply

Abstract

The invention discloses a back electromotive force absorption device and method for a vehicle-mounted low-voltage power supply, and belongs to the technical field of vehicle-mounted standby power supplies. Comprising a super capacitor module, a resistor module and a mosfet module. The resistor module and the mosfet module are connected in series and then are connected in parallel with the super capacitor module and the vehicle-mounted low-voltage power supply; the vehicle-mounted low-voltage power supply, the positive electrode of the super-capacitor module and the other end of the mosfet module are connected and connected with a counter electromotive force pulse, and the vehicle-mounted low-voltage power supply, the negative electrode of the super-capacitor module and the other end of the resistor module are connected and grounded. The super-capacitor module is normally connected with a vehicle-mounted low-voltage power supply, can respond to counter electromotive force pulses at any time, controls quick connection and disconnection of the parallel resistor module according to hysteresis voltage, maintains bus voltage stability, relieves resistive virtual voltage of the super-capacitor module, and shares absorption of reverse current side by side with a super-capacitor. The scheme is simple, good in effect, low in cost and suitable for mass production.

Description

Technical Field

[0001] The invention relates to the technical field of vehicle-mounted standby power supplies, and in particular to a back electromotive force absorption method of a vehicle-mounted low-voltage power supply. Background Art

[0002] With the development of automobile electrification, the increasing amount of low-voltage electrical equipment and power demand require the on-board low-voltage power supply to always have more power and high-rate discharge capability. This can be achieved by adjusting and maintaining the battery in a higher SOC state on the basis of the current battery to meet the necessary, occasional and gradually increasing low-voltage load power supply requirements under the requirements of new vehicles and new functions. However, at the same time, the new demand also includes more frequent and higher-rate energy recovery capabilities. For the battery, when it is close to or already fully charged SOC, the charging rate is gradually reduced to 0, which creates an irreconcilable contradiction with the demand for high charging rate in this state. In addition, the new requirements for the power supply operating temperature range of the whole vehicle are gradually expanding downward and are required to cover -40℃. As we all know, below 0℃, the battery charging and discharging performance drops sharply. The continuous charging and discharging rate of the battery at -20℃ will be reduced to less than 0.5C, and -40℃ will be as low as 0.2C. At this low temperature, it is also necessary to approach or fully charged state High-rate pulse feeding, if the battery capacity is not enlarged by dozens of times, it is impossible to achieve it based on the current battery capacity. Therefore, we need to expand our thinking to find solutions. Summary of the invention

[0003] In view of the defects of the prior art, the present invention provides a back-electromotive force absorption device. Due to the high power characteristics and excellent low-temperature performance of the supercapacitor, it can be matched with a battery to achieve high-rate charge and discharge pulse conditions over the full temperature range and a wider operating voltage, and can easily achieve back-electromotive force absorption covering -40°C and above the battery's full-charge voltage, eliminating the stringent requirements on the battery and reserving the possibility for new low-voltage electrical equipment with pulsed electricity consumption in new cars.

[0004] In order to achieve the above object, the present invention provides a back electromotive force absorption device for a vehicle-mounted low-voltage power supply, comprising a supercapacitor module, a resistor module, and a mosfet module;

[0005] The resistance module and the mosfet module are connected in series and then connected in parallel with the supercapacitor module and the on-board low-voltage power supply; the on-board low-voltage power supply, the positive electrode of the supercapacitor module and the other end of the mosfet module are connected and connected to the back electromotive force pulse, and the on-board low-voltage power supply, the negative electrode of the supercapacitor module and the other end of the resistance module are connected and grounded.

[0006] Furthermore, the operating voltage of the supercapacitor module covers the operating voltage of the on-board low-voltage power supply.

[0007] Furthermore, the resistance value of the resistor module is in the same order of magnitude as the resistance value of the supercapacitor module.

[0008] Furthermore, the mosfet module is a mosfet group, a front end of which is connected to the vehicle-mounted low-voltage power supply and the positive electrode of the supercapacitor module, and a rear end is connected to the resistor module.

[0009] Furthermore, the current carrying capacity of the mosfet module covers the current carrying capacity requirement of the back electromotive force pulse working condition.

[0010] The present invention also provides a method for absorbing back electromotive force of a vehicle-mounted low-voltage power supply, based on the back electromotive force absorption device of the vehicle-mounted low-voltage power supply as described above, comprising:

[0011] (1) In the initial state or when the bus voltage of the on-board low-voltage power supply does not reach the full-power voltage of the on-board low-voltage power supply, the supercapacitor module and the on-board low-voltage power supply always maintain the same voltage, jointly supplying power to the load or recovering the back-electromotive force pulse and reusing it;

[0012] (2) When the bus voltage of the on-board low-voltage power supply exceeds the full-power voltage of the on-board low-voltage power supply, the on-board low-voltage power supply is automatically cut off, and the supercapacitor module recovers the back-electromotive force pulse;

[0013] (3) When the on-board low-voltage power bus voltage exceeds the mosfet module closing voltage, the mosfet module closes, and the resistor module and the supercapacitor module are connected in parallel to absorb the back electromotive force pulse together;

[0014] (4) When the on-board low-voltage power bus voltage drops back to the MOSFET disconnection voltage, the MOSFET module is disconnected, and the resistor module will no longer absorb the back-EMF pulse, returning to a state where only the supercapacitor module monitors and absorbs the back-EMF pulse, and uses the recovered electric energy to discharge or depolarize to restore the voltage;

[0015] (5) When the bus voltage of the on-board low-voltage power supply drops below the full-charge voltage of the on-board low-voltage power supply, the on-board low-voltage power supply is restored to use, and the supercapacitor module is connected in parallel with the on-board low-voltage power supply to supply power to the load or to absorb the back electromotive force together.

[0016] Beneficial effects of the present invention:

[0017] The supercapacitor module of the present invention is often connected to the vehicle-mounted low-voltage power supply, and can achieve the response to the back electromotive force pulse at any time, can solve the rapid response absorption of the pulse current before the resistor is cut in, can avoid voltage spikes, maintain the bus voltage stability, and the power recovery of the pulse entering the supercapacitor module can be reused, thereby improving the energy utilization rate. A mosfet switch is used to control the rapid access and disconnection of the parallel resistor module according to the hysteresis voltage, thereby ensuring the stability of the bus voltage and the safety of the supercapacitor. The use of parallel resistors ensures the stability of the bus voltage at the moment of large pulses, alleviates the resistive virtual pressure of the supercapacitor module, and shares the absorption of the reverse current with the supercapacitor. The resistance value, size, material, etc. are highly configurable, the working condition response range is wide, and the energy recovery rate can be adjusted through reasonable configuration. This solution is simple, effective, low-cost, and suitable for mass production. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic structural diagram of a back electromotive force absorption device of a vehicle-mounted low-voltage power supply according to an embodiment of the present invention.

[0019] Figure 2 Schematic diagram of voltage change during the back electromotive force absorption process of the on-board low-voltage power supply according to an embodiment of the present invention.

[0020] Among them: A, back-EMF absorption module; B, on-board low-voltage battery; a, back-EMF pulse; 1, supercapacitor module; 2, Mosfet module; 3, resistor module; 4, high-side drive module; V0, initial voltage; V1, Mosfet disconnect voltage; V2, Mosfet closing voltage; V3, the upper limit of the vehicle-mounted low-voltage power bus voltage. DETAILED DESCRIPTION

[0021] The present invention is further explained below in conjunction with the accompanying drawings and embodiments. It should be noted that, unless otherwise defined, the technical terms or scientific terms used herein should be understood by a person with ordinary skills in the technical field to which the present invention belongs. All the values ​​from the lowest value to the highest value listed herein refer to all the values ​​obtained by incrementing the lowest value to the highest value by one unit when the difference between the lowest value and the highest value is more than two units.

[0022] like Figure 1 As shown, an embodiment of the present invention provides a back electromotive force absorption device for a vehicle-mounted low-voltage power supply, comprising a super capacitor module 1, a resistor module 3, and a mosfet module 2.

[0023] The resistance module 3 and the mosfet module 2 are connected in series and connected in parallel with the supercapacitor module 1 and the on-board low-voltage power supply B, wherein the on-board low-voltage power supply B, the positive electrode of the supercapacitor module 1 and the other end of the mosfet module 2 are connected and connected to the back electromotive force pulse a, and the on-board low-voltage power supply B, the negative electrode of the supercapacitor module 1 and the other end of the resistance module 3 are connected and grounded.

[0024] The operating voltage of the supercapacitor module 1 covers the operating voltage of the on-board low-voltage power supply B and is slightly higher than the full charge voltage of the on-board low-voltage power supply B.

[0025] The resistance value of the resistor module 3 is in the same order of magnitude as that of the super capacitor module 1 , and the temperature rise generated by the conversion of electrical energy by the resistor module 3 meets the requirements for vehicle use.

[0026] The mosfet module 2 is a mosfet group, the front end of which is connected to the vehicle low-voltage power supply B and the positive electrode of the supercapacitor module 1, and the rear end is connected to one end of the resistor module 3. The current carrying capacity of the mosfet module 2 covers the current carrying capacity requirements of the back electromotive force pulse working condition a.

[0027] The embodiment of the present invention further provides a method for absorbing back electromotive force of a vehicle-mounted low-voltage power supply, based on the back electromotive force absorption device of the vehicle-mounted low-voltage power supply as described above, comprising:

[0028] S101. In the initial state or when the bus voltage of the on-board low-voltage power supply is not fully charged, the supercapacitor module and the on-board low-voltage power supply always maintain the same voltage, jointly supplying power to the load or recovering the back electromotive force pulse and reusing it.

[0029] S102: When the bus voltage of the on-board low-voltage power supply exceeds the full-charge voltage of the on-board low-voltage power supply, the on-board low-voltage power supply is automatically cut off, and the supercapacitor module recovers the back electromotive force pulse.

[0030] S103. When the on-board low-voltage power bus voltage exceeds the mosfet module closing voltage V2, the mosfet module is closed, and the resistance module and the supercapacitor module are connected in parallel to absorb the back electromotive force pulse together.

[0031] S104. When the on-board low-voltage power bus voltage drops back to the mosfet disconnection voltage V1, the mosfet module is disconnected, the resistor module no longer absorbs the back electromotive force pulse, and the state is restored to where only the supercapacitor module monitors and absorbs the back electromotive force pulse, and the voltage is restored by discharging the recovered electric energy and depolarization.

[0032] S105. When the bus voltage of the on-board low-voltage power supply drops below the full-charge voltage of the on-board low-voltage power supply, the on-board low-voltage power supply is restored to use, and the supercapacitor module is connected in parallel with the on-board low-voltage power supply to supply power to the load or absorb back electromotive force together.

[0033] Figure 2 A schematic diagram of the bus voltage change of the on-board low-voltage power supply during the back-electromotive force absorption process of the on-board low-voltage power supply is given.

[0034] The above are specific embodiments of the present invention. It should be noted that in the specific description of these embodiments, for the sake of concise description, this specification cannot provide a detailed description of all features of the actual embodiments. Without departing from the spirit and scope of the present invention, those skilled in the art may modify and replace the embodiments of the present invention, and the resulting embodiments are also within the scope of protection of the present invention.

Claims

1. A back electromotive force absorption device for a vehicle-mounted low-voltage power supply, characterized in that: Including super capacitor module, resistor module, mosfet module; The resistance module and the mosfet module are connected in series and then connected in parallel with the supercapacitor module and the on-board low-voltage power supply; the on-board low-voltage power supply, the positive electrode of the supercapacitor module and the other end of the mosfet module are connected and connected to the back electromotive force pulse, and the on-board low-voltage power supply, the negative electrode of the supercapacitor module and the other end of the resistance module are connected and grounded.

2. The back electromotive force absorption device of the vehicle-mounted low-voltage power supply according to claim 1, characterized in that: The operating voltage of the supercapacitor module covers the operating voltage of the on-board low-voltage power supply.

3. The back electromotive force absorption device of the vehicle-mounted low-voltage power supply according to claim 1, characterized in that: The resistance value of the resistor module is in the same order of magnitude as the resistance value of the supercapacitor module.

4. The back electromotive force absorption device of the vehicle-mounted low-voltage power supply according to claim 1, characterized in that: The mosfet module is a mosfet group, a front end of which is connected to the vehicle-mounted low-voltage power supply and the positive electrode of the supercapacitor module, and a rear end is connected to the resistor module.

5. The back electromotive force absorption device of the vehicle-mounted low-voltage power supply according to claim 1, characterized in that: The current carrying capacity of the mosfet module covers the current carrying capacity requirement of the back electromotive force pulse working condition.

6. A method for absorbing back electromotive force of a vehicle-mounted low-voltage power supply, based on the back electromotive force absorption device of a vehicle-mounted low-voltage power supply as claimed in any one of claims 1 to 5, characterized in that: include: (1) In the initial state or when the bus voltage of the on-board low-voltage power supply does not reach the full-power voltage of the on-board low-voltage power supply, the supercapacitor module and the on-board low-voltage power supply always maintain the same voltage, jointly supplying power to the load or recovering the back-electromotive force pulse and reusing it; (2) When the bus voltage of the on-board low-voltage power supply exceeds the full-power voltage of the on-board low-voltage power supply, the on-board low-voltage power supply is automatically cut off, and the supercapacitor module recovers the back-electromotive force pulse; (3) When the on-board low-voltage power bus voltage exceeds the mosfet module closing voltage, the mosfet module closes, and the resistor module and the supercapacitor module are connected in parallel to absorb the back electromotive force pulse together; (4) When the on-board low-voltage power bus voltage drops back to the MOSFET disconnection voltage, the MOSFET module is disconnected, and the resistor module will no longer absorb the back-EMF pulse, returning to a state where only the supercapacitor module monitors and absorbs the back-EMF pulse, and uses the recovered electric energy to discharge or depolarize to restore the voltage; (5) When the bus voltage of the on-board low-voltage power supply drops below the full-charge voltage of the on-board low-voltage power supply, the on-board low-voltage power supply is restored to use, and the supercapacitor module is connected in parallel with the on-board low-voltage power supply to supply power to the load or to absorb the back electromotive force together.

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