Load throwing protection circuit of starting battery and power supply device of new energy automobile

Abstract

The utility model discloses a throw load protection circuit of a starting battery and a power supply device of a new energy automobile, a control circuit is connected in series between a battery general cathode and a battery bus cathode of the starting battery, the control circuit comprises a charging switch, the throw load protection circuit is connected in parallel with the control circuit, and the charging switch is connected in parallel with the throw load protection circuit. Comprising an energy storage unit and a one-way switch unit which are connected in series, the anodes of the one-way switch unit and the energy storage unit are close to the total cathode of the battery relative to the cathodes, so that the throw load protection circuit and the starting battery are connected in series to form a follow current loop at the moment when the charging switch is switched off, and the energy storage unit absorbs energy. Therefore, the voltage between the battery bus positive electrode and the battery bus negative electrode is stabilized below the preset threshold value, the load throwing speed is high, and safety and stability are achieved.

Description

Technical Field

[0001] The utility model relates to a power supply device, in particular to a load dump protection of a starting battery in the power supply device. Background Art

[0002] In order to replace lead-acid batteries for car starting, one technical route is to use supercapacitors, which have a wide operating temperature range, large charging current and short charging time, and have a certain ability to resist overcharging. The disadvantages are that the single-cell operating voltage is low, the internal resistance is large, a larger number of series connections are required, and the storage energy is limited. It is only suitable for short-term high-power output occasions. It usually needs to be used in parallel with a battery. It is expensive and there is an electrolyte leakage problem, and the overall application cost is high.

[0003] The second technical route is to use lithium-ion batteries (especially lithium iron phosphate batteries) as starting batteries. Lithium-ion batteries have the advantages of high energy density, small size, and long life, but they need to be equipped with protection boards to prevent overcharging and over-discharging. For example, after the vehicle is started, the on-board generator supplies power to the on-board equipment and charges the starting battery at the same time. When the output voltage of the on-board generator is greater than the threshold VH1 (for example, 29V) or there is a large inconsistency in the battery cell voltage, the starting battery may trigger the cell overvoltage protection and thus turn off the charging switch module. The existing starting battery and its protection board, due to the fixed protection time, are prone to false triggering of undervoltage protection and overcurrent protection at the moment of starting due to the drop in battery voltage caused by large current, resulting in the inability to reliably start the car, and even damage to the charging and discharging protection switch device; in addition, when the generator charges the starting battery, due to the inconsistent cell voltage, after the overcharge protection is generated, the charging switch module is disconnected at the moment, and an induced high voltage (up to 65V or more) will be generated between the output busbars P+ and P-, and the generator will dump load. The increase in the generator voltage affects the normal operation of the on-board equipment and even overvoltage damage.

[0004] Therefore, there is an urgent need for a circuit that can perform load dump protection on the starting battery in the new energy battery. Utility Model Content

[0005] The purpose of the utility model is to provide a load dump protection circuit for a starting battery and a power supply device for a new energy vehicle. The load dump protection circuit can provide load dump protection to one side of the load at the moment when the charging switch is disconnected, so that the voltage between the positive electrode of the battery bus and the negative electrode of the battery bus is stabilized below a preset threshold.

[0006] In order to achieve the above-mentioned purpose, the utility model provides a load dump protection circuit of a starting battery, wherein a control circuit is connected in series between the total negative electrode of the starting battery and the negative electrode of the battery bus, the control circuit includes a charging switch, and the load dump protection circuit is connected in parallel with the control circuit, including a series-connected energy storage unit and a unidirectional switch unit, wherein the positive electrode of the unidirectional switch unit and the energy storage unit is adjacent to the total negative electrode of the battery relative to the negative electrode, so that when the charging switch is disconnected, the load dump protection circuit is connected in series with the starting battery to form a freewheeling loop, and the energy storage unit absorbs energy, thereby stabilizing the voltage between the positive electrode of the battery bus and the negative electrode of the battery bus below a preset threshold.

[0007] Wherein, the energy storage unit is a super capacitor or is formed by connecting a plurality of electrolytic capacitors in parallel.

[0008] The unidirectional switch unit is a semiconductor switch tube, which can disconnect the load dump protection circuit due to low voltage difference when the control circuit is turned on, thereby preventing the energy storage unit from charging when the control circuit is working. Specifically, the unidirectional switch unit is a diode or a MOS tube, such as a Schottky diode or an N-type enhanced MOSFET.

[0009] Wherein, the control circuit also includes a current detection circuit and a discharge switch connected in series with the charging switch.

[0010] Among them, the preset threshold is 32V.

[0011] Preferably, the load dump protection circuit further includes a discharge resistor connected in parallel with the energy storage unit, and after the automobile generator is regulated and the voltage drops, the voltage of the energy storage unit can be quickly discharged through the discharge resistor to accelerate the discharge speed of the energy storage unit.

[0012] Specifically, the resistance value of the discharge resistor is 1KΩ to 10KΩ. Of course, the resistance value of the discharge resistor is not limited thereto and can be set according to actual needs.

[0013] Wherein, the starting battery is a lithium-ion battery.

[0014] The present invention also discloses a power supply device for a new energy vehicle, comprising a starting battery, a control circuit, a battery management module and a load dump protection circuit. A control circuit is connected in series between the total negative electrode of the starting battery and the negative electrode of the battery busbar. The battery management module is connected to the control end of the control circuit. The load dump protection circuit is the load dump protection circuit of the above-mentioned starting battery.

[0015] Compared with the prior art, the load dump protection circuit of the utility model can form a freewheeling loop between the load dump protection circuit and the starting battery at the moment when the charging switch is disconnected, and the energy storage unit absorbs energy, thereby stabilizing the voltage between the positive electrode of the battery bus and the negative electrode of the battery bus below a preset threshold. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a structural diagram of the power supply device of the new energy vehicle in the first embodiment of the utility model.

[0017] Figure 2 It is a structural diagram of a power supply device for a new energy vehicle in the second embodiment of the utility model.

[0018] Figures 3 to 5 It is a process diagram of load dumping protection of the power supply device of the utility model new energy vehicle. DETAILED DESCRIPTION

[0019] In order to explain the technical content, structural features, achieved objectives and effects of the present invention in detail, the following is a detailed description in conjunction with the implementation modes and the accompanying drawings.

[0020] refer to Figure 1 The first embodiment of the utility model discloses a power supply device for a new energy vehicle, including a starting battery 30, a control circuit 20, a battery management module 40 and a load dump protection circuit 10. The control circuit 20 is connected in series between the battery total negative electrode B- of the starting battery 30 and the battery bus negative electrode P-. The control circuit 20 includes a charging switch 21, and the battery management module 40 is connected to the control end of the control circuit 20.

[0021] refer to Figure 1 The load dump protection circuit 10 is connected in parallel with the control circuit 20, and includes a series-connected energy storage unit C and a one-way switch unit SK. The positive electrode of the one-way switch unit SK is adjacent to the total negative electrode B- of the battery relative to the negative electrode, so that when the charging switch 21 is disconnected, the load dump protection circuit 10 is connected in series with the starting battery 30 to form a freewheeling loop, and the energy storage unit C absorbs energy, thereby stabilizing the voltage between the positive electrode P+ of the battery bus and the negative electrode P- of the battery bus below a preset threshold. In this embodiment, the energy storage unit C is adjacent to the total negative electrode B- of the battery relative to the one-way switch unit SK. Of course, the energy storage unit C and the one-way switch unit SK can also be swapped, that is, the energy storage unit C is adjacent to the negative electrode P- of the battery bus relative to the one-way switch unit SK.

[0022] The energy storage unit C is a super capacitor or is formed by connecting a plurality of electrolytic capacitors in parallel.

[0023] Wherein, the unidirectional switch unit SK is a Schottky diode or an N-type enhancement MOSFET.

[0024] The control circuit 20 further includes a current detection circuit 23 and a discharge switch 22 connected in series with the charging switch 21 .

[0025] The preset threshold is 32 V. Of course, the preset threshold can also be fine-tuned by adjusting the parameters of the energy storage unit C.

[0026] Wherein, the starting battery 30 is a lithium-ion battery.

[0027] refer to Figure 2 , which is the second embodiment of the utility model. Based on the first embodiment, in the second embodiment, the load dump protection circuit 10a also includes a discharge resistor R connected in parallel with the energy storage unit C. After the automobile generator is adjusted and the voltage drops, the voltage of the energy storage unit C can be quickly discharged through the discharge resistor R, thereby accelerating the discharge speed of the energy storage unit C.

[0028] Specifically, the resistance value of the discharge resistor R is 1KΩ to 10KΩ. Of course, the resistance value of the discharge resistor R is not limited thereto and can be set according to actual needs.

[0029] refer to Figures 3 to 5 , describing the working process of the load dump protection circuit 10a of the utility model:

[0030] refer to Figure 3 After the vehicle is started, the on-board generator supplies power to the on-board equipment and charges the starting battery 30. At this time, the current I flows from the total negative electrode B- of the battery through the current detection circuit 23, the discharge switch 22 and the charging switch 21 to the negative electrode P- of the battery busbar. The control circuit 20 and the starting battery 30 are connected in series to form a charging circuit. At this time, on the load dump protection circuit 10a, since the voltage drop across the control circuit 20 is very low, much smaller than the conduction voltage of the unidirectional switch unit SK, the unidirectional switch unit SK is disconnected, and the load dump protection circuit 10a is in the cut-off state.

[0031] refer to Figure 4When the output voltage of the vehicle generator is greater than the first threshold VH1 (for example, 29V) or there is a large inconsistency in the battery cell voltage, the battery management module 40 triggers the cell overvoltage protection and turns off the charging switch 21. At the moment when the charging switch 21 is turned off, the voltage drop between the total negative electrode B- of the battery and the negative electrode P- of the battery bus is greater than the conduction voltage difference of the unidirectional switch unit SK, the unidirectional switch unit SK is turned on, and the current I flows from the total negative electrode B- of the battery through the energy storage unit C and the unidirectional switch unit SK to the negative electrode P- of the battery bus. The load dump protection circuit 10a is connected in series with the starting battery 30 to form a freewheeling loop, and the energy storage unit C begins to charge, thereby stabilizing the voltage between the positive electrode P+ of the battery bus and the negative electrode P- of the battery bus below the preset threshold.

[0032] refer to Figure 5 , when the fault is eliminated and the charging of the starting battery 30 is resumed to close the charging switch 21, the current is released from the positive electrode of the energy storage unit C through the discharge resistor R to the negative electrode of the energy storage unit C, and the power in the energy storage unit C will be quickly discharged by the discharge resistor R to prevent the energy storage unit C from affecting the stability of the voltage between the positive electrode P+ of the battery bus and the negative electrode P- of the battery bus when it is discharged. Of course, if there is no discharge resistor R in the load dump protection circuit 10a, then after the fault is eliminated and the charging of the starting battery 30 is resumed to close the charging switch 21, the power in the energy storage unit C is gradually released from the control circuit 20 until the voltage difference between the two sides of the energy storage unit C is lower than a certain value so that the voltage across the unidirectional switch unit SK is lower than its conduction voltage and the load dump protection circuit 10 is disconnected.

[0033] The above disclosure is only the preferred embodiment of the present invention, which certainly cannot be used to limit the scope of rights of the present invention. Therefore, equivalent changes made according to the scope of the patent application of the present invention are still within the scope covered by the present invention.

Claims

1. A load dump protection circuit for a starting battery, wherein a control circuit is connected in series between the total negative electrode of the starting battery and the negative electrode of the battery busbar, and the control circuit includes a charging switch, characterized in that: The load dump protection circuit is connected in parallel with the control circuit, and includes a series-connected energy storage unit and a unidirectional switch unit. The positive poles of the unidirectional switch unit and the energy storage unit are adjacent to the total negative pole of the battery relative to the negative pole, so that at the moment when the charging switch is disconnected, the load dump protection circuit is connected in series with the starting battery to form a freewheeling loop, and the energy storage unit absorbs energy, thereby stabilizing the voltage between the positive pole of the battery bus and the negative pole of the battery bus below a preset threshold.

2. The load dump protection circuit according to claim 1, wherein: The energy storage unit is a super capacitor or is formed by connecting a plurality of electrolytic capacitors in parallel.

3. The load dump protection circuit according to claim 1, wherein: The unidirectional switch unit is a semiconductor switch tube.

4. The load dump protection circuit according to claim 3, wherein: The unidirectional switch unit is a diode or a MOS tube.

5. The load dump protection circuit according to claim 1, wherein: The control circuit also includes a current detection circuit and a discharge switch connected in series with the charging switch.

6. The load dump protection circuit according to claim 1, wherein: The preset threshold is 32V.

7. The load dump protection circuit according to claim 1, wherein: The load dump protection circuit also includes a discharge resistor connected in parallel with the energy storage unit.

8. The load dump protection circuit according to claim 7, wherein: The resistance of the discharge resistor is 1KΩ to 10KΩ.

9. The load dump protection circuit according to claim 1, wherein: The starting battery is a lithium-ion battery.

10. A power supply device for a new energy vehicle, characterized in that: The invention comprises a starting battery, a control circuit, a battery management module and a load dump protection circuit, wherein a control circuit is connected in series between the total negative electrode of the starting battery and the negative electrode of the battery bus, the battery management module is connected to the control end of the control circuit, and the load dump protection circuit is the load dump protection circuit of the starting battery as described in any one of claims 1 to 9.

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