MOSFET tube on-line detection circuit for electric vehicle power supply system

Abstract

The utility model relates to the technical field of charge and discharge management, and discloses an MOSFET on-line detection circuit for an electric automobile power supply system, which comprises a power supply, the power supply is connected with a load through a switching circuit, the switching circuit adopts a multi-path parallel branch structure formed by high-power MOSFETs and is connected with a driving module, the driving module is connected with a processor, and the processor is connected with the power supply. The processor is further connected with the comparison module, the comparison module is connected with the voltage sampling module, the voltage sampling module is used for collecting voltage information of a plurality of different position points in the switching circuit, and the comparison module is used for comparing the voltage information of the different position points and outputting a comparison result to the processor. Under the condition that normal operation of equipment is not affected, the working state of each high-power MOSFET tube in parallel branches can be detected online in real time by using acquired voltage information, and safe and reliable operation of the circuit can be ensured.

Description

Technical Field

[0001] The utility model belongs to the technical field of charge and discharge management, and specifically relates to a MOSFET tube online detection circuit for an electric vehicle power supply system. Background Art

[0002] The switch module composed of high-power MOSFET tubes is a commonly used switching device in the power supply circuit and is one of the key devices. In some high-reliability application occasions such as the battery power supply system of new energy vehicles, since the operation of the entire vehicle depends on battery power supply, once a fault occurs, it will affect the operation of the entire vehicle, so it is necessary to obtain the working status of the high-power MOSFET tube in time. However, the existing battery power supply system mostly uses parking detection for the detection of high-power MOSFET tubes, but it is impossible to obtain the corresponding working status by detecting the working parameters of each high-power MOSFET tube, such as whether there are faults such as inability to conduct, inability to disconnect, and adhesion. Therefore, there is a safety hazard. The existing technology can only obtain the overall fault condition of the switch module in the battery power supply system, and more detailed diagnosis is required, which causes a poor user experience for customers. Utility Model Content

[0003] The utility model provides a MOSFET tube online detection circuit for an electric vehicle power supply system, which solves the technical problem that the existing battery power supply system mostly uses parking detection for the detection of high-power MOSFET tubes, but cannot obtain the corresponding working state by detecting the voltage state of each high-power MOSFET tube.

[0004] The utility model can be realized through the following technical solutions:

[0005] A MOSFET tube online detection circuit for an electric vehicle power supply system comprises a power supply, wherein the power supply is connected to a load via a switch circuit, wherein the switch circuit adopts a multi-way parallel branch structure composed of high-power MOSFET tubes, and is connected to a drive module, wherein the drive module is connected to a processor, and the processor is also connected to a comparison module, wherein the comparison module is connected to a voltage sampling module, wherein the voltage sampling module is used to collect voltage information of multiple different position points in the switch circuit, and wherein the comparison module is used to compare the voltage information of different position points and output the comparison result to the processor.

[0006] Furthermore, each parallel branch of the switch circuit is formed by two high-power MOSFET tubes connected back to back, and both are configured as NMOS tubes. The voltage sampling module is used to collect the midpoint voltage of each parallel branch, i.e., the source voltage, and the two end point voltages, i.e., the drain voltage.

[0007] The comparison module includes a subtractor circuit and a first comparator circuit and a second comparator circuit. The two input terminals of the subtractor circuit are respectively connected to a midpoint voltage and an end point voltage, and the output terminal is respectively connected to an input terminal of the first comparator circuit and an input terminal of the second comparator circuit.

[0008] Another input terminal of the first comparator circuit is connected to a first reference voltage, and an output terminal thereof is connected to a processor.

[0009] Another input terminal of the second comparator is connected to a second reference voltage, and an output terminal of the second comparator is connected to a processor.

[0010] Furthermore, the first reference voltage is set to 0V, and the second reference voltage is set to the rated voltage of the power supply.

[0011] Furthermore, the voltage sampling module includes two endpoint branches and a midpoint branch corresponding to each parallel branch, each of the midpoint branches is used to collect the midpoint voltage of the corresponding parallel branch, and the two endpoint branches are respectively connected to the two common ends of all parallel branches for collecting the endpoint voltages of the parallel branches. They both include a detection end, an enable end and an output end, the enable end is connected to the processor, the output end is connected to the comparison module, and the detection end is connected to the corresponding position point of the switch circuit.

[0012] Further, the midpoint branch and the end point branch each include a PNP transistor, the emitter of the PNP transistor is connected to the detection end, the base electrode thereof is connected to one end of the resistor R158 and the resistor R159 connected in series, the base electrode thereof is connected to the collector of the NPN transistor, the emitter of the NPN transistor and the other end of the resistor R158 and the resistor R159 connected in series are both connected to the ground, the base electrode thereof is connected to the enable end, and is connected to the ground through the filter capacitor C114,

[0013] The middle point of the series-connected resistors R158 and R159 is connected to the output terminal via a resistor R189, and the output terminal is connected to the ground via a filter capacitor C116.

[0014] Furthermore, it also includes a current sampling module, which is connected to the processor and is used to collect current information of the loop where the power supply, switch circuit and load are located. The processor is also connected to the host computer.

[0015] The beneficial technical effects of the utility model are as follows:

[0016] 1. The utility model adopts a precision voltage-dividing circuit to design the midpoint branch and the end point branch. The processor controls the enabling voltage detection circuit, and detects the midpoint end and the power supply end and the load end of the parallel branch, namely the source voltage and the drain voltage of the MOSFET, through the precision voltage-dividing resistor. The relationship between the source voltage, the drain voltage and the threshold voltage of the MOSFET is calculated through the comparison module, which provides a data basis for the processor to judge the fault conditions of the two high-power MOSFET tubes in the parallel branch in the diagnosis state, ensures the smooth progress of real-time online detection, and provides guarantee for the normal operation of the circuit.

[0017] 2. The utility model adopts a redundant design of multiple parallel branches, which can promptly disconnect the damaged parallel branches to ensure the normal operation of the equipment. At the same time, it can also interact with maintenance personnel with the help of the host computer to issue alarms for parallel branches that may fail in the future, thereby preventing more circuit damage and improving the safety level of the circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic diagram of the overall structural framework of the utility model;

[0019] Figure 2 It is a schematic diagram of the circuit connection structure of the comparison module of the utility model;

[0020] Figure 3 Schematic diagram of the specific structure of the midpoint branch and the end point branch of the utility model, wherein the connection terminal RS_1 in Figure (a) and the connection terminal RS_2 in Figure (b) are respectively connected to the midpoint of the corresponding parallel branch as detection terminals, the connection terminal LOAD in Figure (c) is connected to the other common terminal of all parallel branches close to the load position, and the connection terminal BAT+ in Figure (d) is connected to a common terminal of all parallel branches close to the power supply position;

[0021] The connection terminals RS_1_EN, RS_1_M, RS_2_EN, RS_2_M, BAT_EN, BAT_M, LOAD_EN, and LOAD_M in Figures (a)-(d) are all connected to the processor MCU. DETAILED DESCRIPTION

[0022] The specific implementation of the utility model is described in detail below with reference to the accompanying drawings and preferred implementation examples.

[0023] like Figure 1As shown, the utility model provides an online diagnosis detection circuit for a high-power MOSFET tube, including a power supply, which is connected to a load through a switch circuit, and the switch circuit adopts a multi-way parallel branch structure composed of a high-power MOSFET tube, which is connected to a drive module, and the drive module is connected to a processor, and the processor is also connected to a comparison module, and the comparison module is connected to a voltage sampling module, and the voltage sampling module is used to collect voltage information of multiple different position points in the switch circuit, and the comparison module is used to compare the voltage information of different position points, and output the comparison result to the processor. In this way, the voltage sampling module is used to collect the voltage information of different position points in the switch circuit, and the relevant voltage measurement of the high-power MOSFET tube is completed. With the help of the comparison module, these voltage information are compared and processed, and the comparison result is output to the processor, which provides a data basis for the processor to detect the working state of each high-power MOSFET tube in the discharge circuit in real time online, and improves the safety and reliability of the circuit operation; at the same time, a redundant design composed of multiple parallel branches is adopted, and the damaged parallel branches are disconnected in time to ensure the normal operation of the load power supply and improve the safety level of the circuit.

[0024] The details are as follows:

[0025] Each parallel branch of the switch circuit is formed by two high-power MOSFET tubes connected back to back, such as NMOS tubes. The voltage sampling module is used to collect the midpoint voltage and two end point voltages of each parallel branch, such as Figure 2 As shown, the comparison module includes a subtractor circuit and a first comparator circuit and a second comparator circuit, the two input ends of the subtractor circuit are respectively connected to a midpoint voltage and an endpoint voltage, the output end is respectively connected to an input end of the first comparator circuit and an input end of the second comparator circuit, the other input end of the first comparator circuit is connected to a first reference voltage, and its output end is connected to a processor, the other input end of the second comparator is connected to a second reference voltage, and its output end is connected to a processor. In this way, according to the comparison result of the difference between the midpoint voltage and the endpoint voltage of each high-power MOSFET tube and the first reference voltage such as 0V and the second reference voltage such as the rated voltage of the power supply, the processor can more accurately obtain the working state of the high-power MOSFET tube and output a more reliable detection result.

[0026] During detection, the processor controls at least one parallel branch to be in normal working state through the driving module to ensure normal power supply to the load, one parallel branch is in detection state, and the remaining parallel branches are in idle state. If there are three parallel branches, one can be in working state, one can be in detection state, and one can be in idle state. The subtractor circuit is used to obtain the difference between the midpoint voltage and the end point voltage of the corresponding position point of the parallel branch in the detection state, and the first comparator circuit and the second comparator circuit are used to obtain the relationship between the difference and 0V and the rated voltage of the power supply, which is uploaded to the processor. The processor obtains the working state of the high-power MOSFET tube in the parallel branch in the detection state, such as the fault condition, and repeats the above process to complete the detection of all parallel branches.

[0027] Since the switch circuit includes multiple parallel branches, they have two common terminals. The voltage sampling module includes two endpoint branches and a midpoint branch corresponding to each parallel branch. Each midpoint branch is used to collect the midpoint voltage of the corresponding parallel branch. The two endpoint branches are respectively connected to the two common terminals of all parallel branches for collecting the endpoint voltages of the parallel branches. They all include a detection terminal, an enable terminal and an output terminal. The enable terminal and the output terminal are both connected to the processor. The detection terminal is connected to the corresponding position point of the switch circuit.

[0028] Specifically, Figure 3 As shown, the midpoint branch and the end point branch both include a PNP transistor, the emitter of the PNP transistor is connected to the detection end, the base electrode of the PNP transistor is connected to one end of the series-connected resistor R158 and resistor R159, the base is connected to the collector of the NPN transistor, the emitter of the NPN transistor and the other end of the series-connected resistor R158 and resistor R159 are both connected to the ground, the base is connected to the enable end, and is connected to the ground through the filter capacitor C114, the middle point of the series-connected resistor R158 and resistor R159 is connected to the output end through the resistor R189, and the output end is connected to the ground through the filter capacitor C116.

[0029] Taking into account the failure of the high-power MOSFET tube, the online detection circuit of the utility model also includes a current sampling module, which is connected to the processor and is used to collect current information of the circuit where the power supply, the switch circuit and the load are located. A current sampling resistor SHUNT can be set near the power supply end, and its resistance rating is very small, such as 0.1mΩ. By detecting the current flowing through the current sampling resistor SHUNT, it is detected whether there is current in the circuit to judge whether the power supply is normal, or according to the current size, the reference load needs to control the output power of the power supply, etc.; at the same time, the processor is also connected to the host computer, and the working status of each high-power MOSFET tube in each parallel branch can be uploaded to the host computer to realize interaction with maintenance personnel, and the high-power MOSFET tube is processed in time. For example, for adhesion faults, the maintenance personnel are notified to perform maintenance, and the parallel branch without faults is controlled to be turned on through the drive module, and the current information sampled by the current sampling module is used as feedback to realize normal power supply of the load; for minor damage faults, an alarm is given to remind maintenance personnel to pay more attention to avoid causing more circuit faults.

[0030] The following takes two groups of back-to-back MOS tubes forming a switch circuit as an example to explain the detection process in detail.

[0031] Two groups of back-to-back MOS tubes QA_1 / QB_1 and QA_2 / QB_2 form two parallel branches to form a redundant discharge circuit. The enable terminals of the corresponding midpoint branches are K1 and K2 respectively. Each parallel branch can work independently or be in the on working state when a large current is required. The current detection module can be used to detect the current size on the SHUNT to make a judgment.

[0032] When testing, the processor controls the two parallel branches to be in working state or diagnostic state in time sharing through the driving module, ensuring that at least one branch is tested when the other branch is working normally, thus completing the online test.

[0033] Note that the source voltages of QA_1 / QB_1 and QA_2 / QB_2 are VDA1, VDB1 and VDA2, VDB2, respectively, and the drain voltages are VSA1, VSB1 and VSA2, VSB2, respectively. The specific detection is as follows:

[0034] QB_1 detection:

[0035] 1> The processor controls QA_2 to be turned on and closed, and QB_2 to be turned on and closed through the driver module, that is, the power supply to the load is executed through QA_2 and QB_2;

[0036] 2> The processor controls QA_1 to turn off open and QB_1 to turn off open through the driver module, and the processor enables the corresponding branch of the voltage sampling module to perform source voltage VS and drain voltage VD detection;

[0037] If VDB1 - VSB1 = Vpower, QB_1 is normal

[0038] If 0 < VDB1 - VSB1 < Vpower, QB_1 is slightly damaged

[0039] If VDB1 = VSB1, QB_1 is stuck close

[0040] 3>The processor controls QA_1 to turn off (open) and QB_1 to turn on (close) through the drive module, and enables the corresponding branch of the voltage sampling module by the processor to perform the detection of the source voltage VS and the drain voltage VD;

[0041] If VDB1 - VSB1 = Vpower, QB_1 is stuck open

[0042] If 0 < VDB1 - VSB1 < Vpower, QB_1 is slightly damaged

[0043] If VDB1 = VSB1, QB_1 is normal

[0044] QA_1 detection:

[0045] 1>The processor controls QA_2 to turn on (close) and QB_2 to turn on (close) through the drive module, that is, to supply power to the load through QA_2 and QB_2 for execution

[0046] 2>The processor controls QB_1 to turn on (close) and QA_1 to turn off (open) through the drive module, and enables the corresponding branch of the voltage sampling module by the processor to perform the detection of the source voltage VS and the drain voltage VD;

[0047] If VSA1 - VDA1 = Vpower, QA_1 is normal

[0048] If 0 < VSA1 - VDA1 < Vpower, QA_1 is slightly damaged

[0049] If VSA1 = VDA1, QA_1 is stuck close

[0050] 3>The processor controls QB_1 to turn on (close) and QA_1 to turn on (close) through the drive module, and enables the corresponding branch of the voltage sampling module by the processor to perform the detection of the source voltage VS and the drain voltage VD;

[0051] If VSA1 - VDA1 = Vpower, QA_1 is stuck open

[0052] If 0 < VSA1 - VDA1 < Vpower, QA_1 is slightly damaged

[0053] If VSA1 = VDA1, QA_1 is normal

[0054] Detection of QB_2:

[0055] 1. The processor controls QA_1 to conduct (close) and QB_1 to conduct (close) through the drive module, that is, power is supplied to the load through QA_1 and QB_1 for execution

[0056] 2. The processor controls QA_2 to turn off (open) and QB_2 to turn off (open) through the drive module, and enables the corresponding branch of the voltage sampling module by the processor to perform source voltage VS and drain voltage VD detection;

[0057] If VDB2 - VSB2 = Vpower, QB_2 is normal

[0058] If 0 < VDB2 - VSB2 < Vpower, QB_2 is slightly damaged

[0059] If VDB2 = VSB2, QB_2 is stuck in the conducting state (stuck close)

[0060] 3. The processor controls QA_2 to turn off (open) and QB_2 to conduct (close) through the drive module, and enables the corresponding branch of the voltage sampling module by the processor to perform source voltage VS and drain voltage VD detection;

[0061] If VDB2 - VSB2 = Vpower, QB_2 is stuck in the off state (stuck open)

[0062] If 0 < VDB2 - VSB2 < Vpower, QB_2 is slightly damaged

[0063] If VDB2 = VSB2, QB_2 is normal

[0064] Detection of QA_2:

[0065] 1. The processor controls QA_1 to conduct (close) and QB_1 to conduct (close) through the drive module, that is, power is supplied to the load through QA_1 and QB_1 for execution

[0066] 2. The processor controls QB_2 to conduct (close) and QA_2 to turn off (open) through the drive module, and enables the corresponding branch of the voltage sampling module by the processor to perform source voltage VS and drain voltage VD detection;

[0067] If VSA2 - VDA2 = Vpower, QA_2 is normal

[0068] If 0 < VSA2 - VDA2 < Vpower, QA_2 is slightly damaged

[0069] If VSA2 = VDA2, QA_2 is stuck close

[0070] 3>The processor controls QB_2 to close and QA_2 to close through the drive module, and enables the corresponding branch of the voltage sampling module by the processor to perform source voltage VS and drain voltage VD detection;

[0071] If VSA2 - VDA2 = Vpower, QA_2 is stuck open

[0072] If 0 < VSA2 - VDA2 < Vpower, QA_2 is slightly damaged

[0073] If VSA2 = VDA2, QA_2 is normal

[0074] Among them, "stuck close" means that the control MOS is disconnected, but actually conducts and cannot be disconnected; "stuck open" means that the control MOS is conducted, but actually disconnected and cannot be conducted.

[0075] Then, according to the fault states of QA_1 / QB_1 and QA_2 / QB_2, the processor controls the parallel branches without faults to work through the drive module, uses the current information detected by the current detection module as feedback to achieve normal power supply to the load, and uploads the fault states to the host computer at the same time. The host computer notifies the maintenance personnel to perform corresponding processing on QA_1 / QB_1 and QA_2 / QB_2 in time.

[0076] Although the specific implementation manners of the present invention are described above, those skilled in the art should understand that these are only examples. Without departing from the principle and essence of the present invention, various changes or modifications can be made to these implementation manners. Therefore, the protection scope of the present invention is defined by the appended claims.

Claims

1. A MOSFET tube online detection circuit for an electric vehicle power supply system, characterized in that: The invention comprises a power supply, which is connected to a load through a switch circuit. The switch circuit adopts a multi-way parallel branch structure composed of a high-power MOSFET tube, which is connected to a drive module. The drive module is connected to a processor. The processor is also connected to a comparison module. The comparison module is connected to a voltage sampling module. The voltage sampling module is used to collect voltage information of multiple different position points in the switch circuit. The comparison module is used to compare the voltage information of different position points and output the comparison result to the processor.

2. The MOSFET tube online detection circuit for electric vehicle power supply system according to claim 1, characterized in that: Each parallel branch of the switch circuit is formed by two high-power MOSFET tubes connected back to back, and both are set as NMOS tubes. The voltage sampling module is used to collect the midpoint voltage of each parallel branch, i.e., the source voltage, and the two end point voltages, i.e., the drain voltage. The comparison module includes a subtractor circuit and a first comparator circuit and a second comparator circuit. The two input terminals of the subtractor circuit are respectively connected to a midpoint voltage and an end point voltage, and the output terminal is respectively connected to an input terminal of the first comparator circuit and an input terminal of the second comparator circuit. Another input terminal of the first comparator circuit is connected to a first reference voltage, and an output terminal thereof is connected to a processor. Another input terminal of the second comparator is connected to a second reference voltage, and an output terminal of the second comparator is connected to a processor.

3. The MOSFET tube online detection circuit for electric vehicle power supply system according to claim 2 is characterized in that: The first reference voltage is set to 0V, and the second reference voltage is set to the rated voltage of the power supply.

4. The MOSFET tube online detection circuit for electric vehicle power supply system according to claim 2, characterized in that: The voltage sampling module includes two endpoint branches and a midpoint branch corresponding to each parallel branch. Each midpoint branch is used to collect the midpoint voltage of the corresponding parallel branch. The two endpoint branches are respectively connected to the two common ends of all parallel branches to collect the endpoint voltages of the parallel branches. They both include a detection end, an enable end and an output end. The enable end is connected to the processor, the output end is connected to the comparison module, and the detection end is connected to the corresponding position point of the switch circuit.

5. The MOSFET tube online detection circuit for electric vehicle power supply system according to claim 4, characterized in that: The midpoint branch and the end point branch both include a PNP transistor, the emitter of the PNP transistor is connected to the detection end, the base electrode of the PNP transistor is connected to one end of the resistor R158 and the resistor R159 connected in series, the base is connected to the collector of the NPN transistor, the emitter of the NPN transistor and the other end of the resistor R158 and the resistor R159 connected in series are both connected to the ground, the base is connected to the enable end, and is connected to the ground through the filter capacitor C114, The middle point of the series-connected resistors R158 and R159 is connected to the output terminal via a resistor R189, and the output terminal is connected to the ground via a filter capacitor C116.

6. The MOSFET tube online detection circuit for electric vehicle power supply system according to claim 1, characterized in that: It also includes a current sampling module, which is connected to the processor and is used to collect current information of the loop where the power supply, switch circuit and load are located. The processor is also connected to the host computer.

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