CN218386846U

CN218386846U - External pre-discharge circuit by using main discharge MOS of BMS

Info

Publication number: CN218386846U
Application number: CN202221862452.7U
Authority: CN
Inventors: 杨麒麟
Original assignee: Scud Energy Technology Co ltd
Current assignee: Scud Energy Technology Co ltd
Priority date: 2022-07-19
Filing date: 2022-07-19
Publication date: 2023-01-24
Anticipated expiration: 2032-07-19

Abstract

The utility model discloses an utilize main MOS that discharges of BMS to carry out external pre-discharge circuit. The external pre-discharge circuit comprises a discharge MOS drive circuit, a resistor R2, a resistor R3, a resistor R4, a capacitor C1, a diode D1 and a triode Q4; the MOS tube Q2 of the discharge MOS driving circuit is respectively connected with a diode D1, a resistor R2, a capacitor C1 and a resistor R3, the capacitor C1 and the resistor R3 are both connected with a triode Q4, and the triode Q4 is connected with the resistor R4; the resistor R4 is connected with the MCU, and the diode D1 and the resistor R2 are both connected with the AFE. Be used for solving prior art and will add independent pre-discharge circuit, need increase cost, high power resistance need occupy very big PCB board area simultaneously to and use the high power cement resistance of examining of producing, need plug-in components, and this control MOS damages the back resistance discharge and can generate heat, has the potential safety hazard problem.

Description

External pre-discharge circuit by using main discharge MOS of BMS

Technical Field

The utility model belongs to the BMS management field; and more particularly, to an external pre-discharge circuit using a main discharge MOS of a BMS.

Background

With the development of lithium batteries, the application of lithium batteries is also gradually increased, and the load types of lithium batteries are many, and the most types are motor loads. Such as: electric bicycle, electric scooter, robot etc. all can use the lithium cell. The motor load generally needs to use a motor controller, and the front end of the motor controller is provided with a large input capacitor to provide a lower-noise input power supply for the controller board. The impedance of the capacitor is very low under the condition of emptying, and if the battery is connected instantly at this time, a very large discharging impact current can be generated, so that the lithium battery is possibly short-circuited or the contact line is ignited. Great potential safety hazard is brought to the use of the lithium battery. Therefore, the BMS is required to have a pre-discharge function for the load, the external capacitor is charged by using a small current, and the main discharge MOS is turned on to discharge after the capacitor is charged to a relatively high voltage. This avoids large current surges when the output is turned on.

The prior art mainly adds an independent pre-discharge circuit, and the pre-discharge circuit generally consists of a pre-discharge switch MOS which is independently controlled and then is connected in series with one or more high-power pre-discharge resistors or PTC and a temperature fuse. Certain cost needs to be increased, meanwhile, the high-power resistor needs to occupy a large PCB area, and the high-power cement resistor which is generally used for production inspection needs to be plugged in, so that the production cost is increased. And the resistor discharges and generates heat after the MOS is damaged, so that potential safety hazards exist, devices such as a temperature fuse and the like are generally required to be added for safety protection, the temperature fuse is required to be fixed on the resistor in production and processing, and production procedures are required to be increased.

SUMMERY OF THE UTILITY MODEL

The utility model provides an utilize main MOS that discharges of BMS to carry out external pre-discharge circuit for solve prior art and will add independent pre-discharge circuit, need the incremental cost, high power resistance need occupy very big PCB board area simultaneously, and use the high power cement resistance of examining of producing, need plug-in components, increase manufacturing cost, and this control MOS damages the back resistance discharge and can generate heat, has the problem of potential safety hazard.

The utility model discloses a following technical scheme realizes:

an external pre-discharge circuit is carried out by using a main discharge MOS of a BMS, and comprises a discharge MOS driving circuit, a resistor R2, a resistor R3, a resistor R4, a capacitor C1, a diode D1 and a triode Q4; the MOS tube Q2 of the discharge MOS driving circuit is respectively connected with a diode D1, a resistor R2, a capacitor C1 and a resistor R3, the capacitor C1 and the resistor R3 are both connected with a triode Q4, and the triode Q4 is connected with the resistor R4;

the resistor R4 is connected with the MCU, and the diode D1 and the resistor R2 are both connected with the AFE.

The utility model provides an utilize BMS ' S main MOS that discharges to carry out external predischarge circuit, the MOS drive circuit that discharges includes MOS pipe Q1 and MOS pipe Q2, MOS pipe Q1 ' S the G utmost point is connected with the CHG end of AFE, MOS pipe Q1 ' S the S utmost point is connected with overvoltage B + end, MOS pipe Q1 ' S the D utmost point is connected with MOS pipe Q2 ' S the D utmost point, MOS pipe Q2 ' S the S utmost point is connected with voltage P + end, MOS pipe Q2 ' S the G utmost point is connected with diode D1, resistance R2, electric capacity C1 and resistance R3 respectively.

The utility model provides an utilize BMS's main MOS that discharges to carry out external predischarge circuit, MOS pipe Q2's G end is connected with diode D1's positive pole, resistance R2's one end, electric capacity C1's one end and resistance R3's one end respectively, diode D1's the negative pole all is connected with AFE's DSG end with resistance R2's the other end, electric capacity C1's the other end and resistance R3's the other end all are connected with triode Q4's collecting electrode C utmost point, triode Q4's projecting pole E utmost point ground connection, triode Q4's base B utmost point is connected with resistance R4's one end, resistance R4's the other end is connected with MCU.

The external pre-discharge circuit is implemented by using a main discharge MOS (metal oxide semiconductor) of a BMS (battery management system), wherein the MCU is connected with an AFE (automatic edge protection) and the grounding end of the AFE is grounded.

A main discharge MOS of a BMS is used for carrying out an external pre-discharge circuit, and a triode Q4 is an NPN type triode.

A diode D1 prevents a series RC loop from influencing the turn-off of a discharge MOS driving loop by utilizing a main discharge MOS of a BMS to carry out an external pre-discharge circuit.

An external pre-discharge circuit is performed by using a main discharge MOS of a BMS, and the resistance value of the resistor R3 is tens of times that of the resistor R2.

A main discharge MOS of a BMS is utilized to carry out an external pre-discharge circuit, and a resistor R4 is a current-limiting resistor of a base electrode B pole of a triode Q4.

The beneficial effects of the utility model are that:

the utility model discloses the G utmost point of the MOS that discharges is gone into to the cluster, uses the output function of discharging in advance that the MOS realized.

The utility model discloses can change into other switch tubes with triode Q4, like MOS, IGBT etc..

The utility model discloses do not use MCU control triode, use hardware switch or other controllable trigger sources to open.

The utility model discloses make BMS cost reduction, PCB face area occupies the reduction simultaneously, promotes production line efficiency, has great improvement help to the product.

The utility model discloses need not increase the pre-discharge circuit of this part, and directly use the discharge MOS of high power on the board, cooperate a small amount of small low-cost peripheral circuit to control, can realize the pre-discharge function

Drawings

Fig. 1 is a prior art pre-discharge circuit diagram.

Fig. 2 is a circuit diagram of the external pre-discharge circuit of the present invention.

Fig. 3 is a graph of RC output voltage versus time in accordance with the present invention.

Detailed Description

The technical solutions in the embodiments of the present invention will be described clearly and completely with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments in the present invention, all other embodiments obtained by a person skilled in the art without creative work belong to the protection scope of the present invention.

A main discharge MOS (metal oxide semiconductor) of a BMS (battery management system) is utilized to carry out external pre-discharge circuit, the G end of an MOS (metal oxide semiconductor) tube Q2 is respectively connected with the anode of a diode D1, one end of a resistor R2, one end of a capacitor C1 and one end of a resistor R3, the cathode of the diode D1 and the other end of the resistor R2 are respectively connected with the DSG end of an AFE (automatic pulse generator), the other end of the capacitor C1 and the other end of the resistor R3 are respectively connected with the collector C electrode of a triode Q4, the emitter E electrode of the triode Q4 is grounded, the base B electrode of the triode Q4 is connected with one end of the resistor R4, and the other end of the resistor R4 is connected with the MCU.

The utility model discloses controllable RC return circuit is gone into to the cluster in the drive circuit of the MOS that discharges, mainly constitutes the controllable resistance R electric capacity C return circuit of MCU by resistance R2 electric capacity C1 and triode Q4, carries out releasing of electric capacity C1 by resistance R3, and diode D1 can prevent to go into the shutoff of the resistance R electric capacity C return circuit influence MOS that discharges.

The resistor R2 and the capacitor C1 use larger resistors and capacitors (R2K-10M C1; the diode D1 is a general small signal diode (small signal diode refers to a signal type diode, which continuously conducts current).

Diode D1 and resistance R2 are parallelly connected, and on diode DSG of AFE was received to diode D1's negative pole, electric capacity C1 and resistance R3 were parallelly connected, and the one end that connects in parallel was received on diode D1's positive pole, and the other end of diode D1 is received on the electric capacity C of triode Q4, and the E of triode Q4 extremely connects BMS's GND, and C, B utmost point series resistance R4 of triode Q4 is connected to MCU output IO.

When pre-discharging is needed, the triode Q4 is controlled to be conducted by the MCU, a diode DSG of the AFE outputs a high-voltage driving signal of a discharging MOS to charge a loop of a resistor R2 and a capacitor C1, and a connecting point of the resistor R2 and the capacitor C1 is connected to a G pole of a discharging MOSMOS tube Q2. Resistor R2 and capacitor C1 form a typical RC charging circuit, and the output voltage will slowly rise from 0, and fig. 3 is a graph of the typical RC output voltage and time. It is known that the voltage of the G-pole of the MOS transistor Q2 will rise slowly after the circuit is added. The voltage of the S pole of the MOS transistor Q2, that is, the voltage of P + = the voltage of the G pole of the MOS transistor Q2 — the MOS transistor Q2Vgs (th); therefore, the slow start control of the output voltage is realized, and the pre-discharge function is realized.

After the pre-discharge is finished, the triode Q4 is turned off, so that the influence of the resistor R2 and the capacitor C1 on the driving circuit can be cut off, and meanwhile, the resistor R3 can discharge the capacitor C1 for the next pre-discharge control. Because resistance R2 has the resistance, in order to avoid the influence to MOS protection shutoff, the current of MOS pipe Q2's G level passes through diode D1 and returns to diode DSG pin when shutting off, has avoided resistance R2's influence, realizes quick shutoff protection.

Claims

1. An external pre-discharge circuit is carried out by using a main discharge MOS of a BMS, and is characterized in that the external pre-discharge circuit comprises a discharge MOS drive circuit, a resistor R2, a resistor R3, a resistor R4, a capacitor C1, a diode D1 and a triode Q4; the MOS tube Q2 of the discharge MOS driving circuit is respectively connected with a diode D1, a resistor R2, a capacitor C1 and a resistor R3, the capacitor C1 and the resistor R3 are both connected with a triode Q4, and the triode Q4 is connected with the resistor R4;

2. The external pre-discharge circuit using the main discharge MOS of the BMS according to claim 1, wherein the discharge MOS driving circuit comprises a MOS transistor Q1 and a MOS transistor Q2, a G-pole of the MOS transistor Q1 is connected to the CHG-terminal of the AFE, an S-pole of the MOS transistor Q1 is connected to the overvoltage B + terminal, a D-pole of the MOS transistor Q1 is connected to a D-pole of the MOS transistor Q2, an S-pole of the MOS transistor Q2 is connected to the voltage P + terminal, and a G-pole of the MOS transistor Q2 is connected to a diode D1, a resistor R2, a capacitor C1, and a resistor R3, respectively.

3. The external pre-discharge circuit using the main discharge MOS of the BMS according to claim 2, wherein the G terminal of the MOS transistor Q2 is connected to the positive terminal of a diode D1, one terminal of a resistor R2, one terminal of a capacitor C1, and one terminal of a resistor R3, respectively, the negative terminal of the diode D1 and the other terminal of the resistor R2 are connected to the DSG terminal of the AFE, the other terminals of the capacitor C1 and the resistor R3 are connected to a collector C terminal of a transistor Q4, an emitter E terminal of the transistor Q4 is grounded, a base B terminal of the transistor Q4 is connected to one terminal of the resistor R4, and the other terminal of the resistor R4 is connected to the MCU.

4. The external pre-discharge circuit using the main discharge MOS of the BMS according to claim 1, wherein the MCU is connected to the AFE, and a ground terminal of the AFE is grounded.

5. The external pre-discharge circuit using the main discharge MOS of the BMS according to claim 1, wherein the transistor Q4 is an NPN-type transistor.

6. The external pre-discharge circuit using the main discharge MOS of the BMS according to claim 3, wherein the diode D1 prevents the series RC loop from affecting the turn-off of the discharge MOS driving loop.

7. The external pre-discharge circuit using the main discharge MOS of the BMS according to claim 3, wherein the resistance of the resistor R3 is several tens times as large as that of the resistor R2.

8. The external pre-discharge circuit using the main discharge MOS of the BMS according to claim 3, wherein the resistor R4 is a current limiting resistor of a base B electrode of the transistor Q4.