CN219496612U - Overvoltage and undervoltage module fault detection circuit of DCDC converter - Google Patents

Abstract

The utility model discloses a fault detection circuit of an overvoltage and undervoltage module of a DCDC converter, which comprises a direct current connector, an overvoltage shutoff module, an undervoltage shutoff module, a first battery and a load which are sequentially connected in series, wherein the circuit also comprises a processing unit, a detection point A arranged on a connecting line of the direct current connector and the overvoltage shutoff module, a detection point C arranged on a connecting line of the overvoltage shutoff module and the undervoltage shutoff module, and a detection point B arranged on a connecting line of the undervoltage shutoff module, the first battery and the load, the processing unit controls the on-off of switches in the overvoltage shutoff module and the undervoltage shutoff module, detects the voltage of each detection point, and judges whether the overvoltage shutoff module and the undervoltage shutoff module have the following faults according to the detected voltage: 1. the overvoltage shutdown module and the undervoltage shutdown module are disconnected; 2. the overvoltage shutdown module and the undervoltage shutdown module are in short circuit; meets the corresponding security targets as ASIL C and ASIL D grades; the method has the advantages of accurate detection and high detection efficiency.

Description

Overvoltage and undervoltage module fault detection circuit of DCDC converter

Technical Field

The utility model relates to the field of DCDC control of automobile electronic new energy automobile technology, in particular to a fault detection circuit for an overvoltage and undervoltage module of a DCDC converter.

Background

On a new energy automobile, the DCDC converter can convert high-voltage direct current of the power battery into low-voltage direct current to supply power for the first battery and the load. The overvoltage shutdown module and the undervoltage shutdown module in the DCDC converter have the functions of protecting a power supply network from the following hazards: unexpected overvoltage output of the DCDC converter leads to unexpected excessive high voltage of a 12V power supply network of the whole vehicle, and leads to damage of electric appliances; DCDC internal short circuit and unexpected under-voltage output result in the first battery and the vehicle 12V power network under-voltage or DCDC power output loss.

Therefore, when the whole vehicle is electrified, the overvoltage shutdown module and the undervoltage shutdown module of the DCDC converter need to be detected so as to verify whether the overvoltage shutdown module and the undervoltage shutdown module are in short circuit or disconnection. And when the overvoltage and undervoltage hazard occurs, the failure of the turn-off path caused by the faults of the overvoltage turn-off module and the undervoltage turn-off module is avoided. The design can effectively improve the diagnosis coverage rate of the latent faults of the DCDC overvoltage shutoff module and the undervoltage shutoff module.

At present, failure modes of short circuit and open circuit in an overvoltage shutdown module and an undervoltage shutdown module of a DCDC converter are tested, and two conventional methods in industry are as follows: the first is the redundancy of the backup of the overvoltage shutdown module and the undervoltage shutdown module, and the scheme can meet the functional safety design of ASIL B ASIL C or ASIL D corresponding to the corresponding safety target. But this design also increases the cost of hardware design and the difficulty of spatial arrangement of the PCB board. The second type is high-voltage power-on self-test, and the pressure difference is formed at the front end and the rear end of the overvoltage shutdown module and the undervoltage shutdown module through the high voltage of the whole vehicle direct-current bus, so that the detection of the latent faults of the overvoltage shutdown module and the undervoltage shutdown module is realized. The DCDC initialization time can be prolonged, so that the power-on time of the whole vehicle is too long, and the complaints of drivers can be caused.

Therefore, designing a fault detection circuit for an overvoltage and undervoltage module with accurate detection and high efficiency is a technical problem to be solved in the industry.

Disclosure of Invention

In order to solve the defects in the prior art, the utility model provides a fault detection circuit for a DCDC converter overvoltage and undervoltage module.

The technical scheme adopted by the utility model is to design a fault detection circuit of an overvoltage and undervoltage module of a DCDC converter, which comprises a direct current connector, an overvoltage shutoff module, an undervoltage shutoff module, a first battery and a load which are sequentially connected in series, and further comprises: the device comprises a direct current connector, an overvoltage shutdown module, a load connection line, a detection point A, a detection point C, a detection point B and a processing unit, wherein the detection point A is arranged on the connection line of the direct current connector and the overvoltage shutdown module, the detection point C is arranged on the connection line of the overvoltage shutdown module and the undervoltage shutdown module, the detection point B is arranged on the connection line of the undervoltage shutdown module, the first battery and the load connection line, the on-off of a switch in the overvoltage shutdown module and the undervoltage shutdown module is controlled, the voltage of the detection point A, the detection point B and the detection point C is detected, and whether the overvoltage shutdown module and the undervoltage shutdown module are normal or not is judged according to the detected voltage.

The detection circuit further includes: a step-down module and a detection switch; the first end of the voltage reduction module is connected with the detection point C, the second end of the voltage reduction module is connected with the detection point B and the third end of the detection switch, and the fourth end of the detection switch is connected with the detection point A; the fifth end of the detection switch and the sixth end of the voltage reduction module are both connected with the processing unit for controlling the on-off of the detection switch and controlling the voltage of the first battery to be reduced by N volts and then sent to the detection point C.

The voltage of the first battery is direct current 12V.

The N volts is 2V.

The detection switch adopts a relay switch.

The technical scheme provided by the utility model has the beneficial effects that:

the utility model can cover the following failure modes of the overvoltage shutdown module and the undervoltage shutdown module: 1. the overvoltage shutdown module and the undervoltage shutdown module are disconnected; 2. the overvoltage shutdown module and the undervoltage shutdown module are in short circuit; meets the corresponding security targets as ASIL C and ASIL D grades; meanwhile, the method has the advantages of accurate detection and high detection efficiency.

Drawings

The utility model is described in detail below with reference to examples and figures, wherein:

FIG. 1 is a circuit state diagram for determining whether an overvoltage shutdown module and an undervoltage shutdown module are open;

FIG. 2 is a circuit state diagram for determining whether an overvoltage shutdown module and an undervoltage shutdown module are shorted;

FIG. 3 is a circuit state diagram for determining whether an overvoltage shutdown module is open;

FIG. 4 is a circuit state diagram for determining whether an under-voltage shutdown module is open;

fig. 5 is a circuit diagram of the preferred embodiment.

Detailed Description

The present utility model will be described in further detail with reference to the drawings and examples, in order to make the objects, technical solutions and advantages of the present utility model more apparent. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the utility model.

The utility model aims to provide a method for detecting latent faults of an overvoltage shutdown module and an undervoltage shutdown module of a DCDC converter and meeting the corresponding safety targets of ASIL C and ASIL D grades.

The utility model discloses a fault detection circuit of an overvoltage and undervoltage module of a DCDC converter, referring to a preferred embodiment shown in FIG. 5, the detection circuit comprises a direct current connection port, an overvoltage shutdown module, an undervoltage shutdown module, a first battery and a load which are sequentially connected in series, and the detection circuit can further comprise, but is not limited to: and the processing unit is arranged on the under-voltage shutdown module, a detection point B on a connecting line of the first battery and the load, and is used for controlling the on-off of a switch in the over-voltage shutdown module and the under-voltage shutdown module, detecting the voltage of the detection point A, the voltage of the detection point B and the voltage of the detection point C, and judging whether the over-voltage shutdown module and the under-voltage shutdown module are normal or not according to the detected voltage. It should be noted that in actual use, the first battery is also connected to the whole vehicle 12V network. The detection is carried out before the whole vehicle is electrified, and the first battery supplies power to the overvoltage and undervoltage modules so that the processing unit can detect the voltage of each detection point.

It should be noted that, in the application of the DCDC converter of the new energy automobile, the dc connection port may be connected to the second battery and the high-low voltage converter, where the first battery may include an in-vehicle low voltage battery, and the second battery may include: a high voltage battery.

With reference to the application of the utility model in a DCDC converter shown in fig. 1, the detection circuit may also include, but is not limited to: a step-down module and a detection switch; the first end of the voltage reduction module is connected with the detection point C, the second end of the voltage reduction module is connected with the detection point B and the third end of the detection switch, and the fourth end of the detection switch is connected with the detection point A; the fifth end of the detection switch and the sixth end of the voltage reduction module are both connected with the processing unit for controlling the on-off of the detection switch and controlling the voltage of the first battery to be reduced by N volts and then sent to the detection point C. It should be noted that the second end of the buck module and the sixth end of the buck module may be one end or different ends.

In a preferred embodiment, the voltage of the first battery may be 12V, and the N V is 2V; it should be noted that the voltage of the first voltage may also be 24V dc or 48V dc, and the above N may also be 4V, which is not limited in the embodiment of the present utility model.

In a preferred embodiment, the detection switch comprises a relay switch or other switch.

Referring to the circuit state diagram shown in fig. 1 for judging whether the overvoltage shutdown module and the undervoltage shutdown module are disconnected, the 12V detection power supply is provided by the battery, the buck module is forbidden to work, the detection switch is controlled to be turned on, and the overvoltage shutdown module and the undervoltage shutdown module are controlled to be turned on; detecting voltages of a detection point A, a detection point B and a detection point C, and calculating voltages of Uab, uac and Ubc; the Uab is the voltage of the detection point A minus the voltage of the detection point B, the Uac is the voltage of the detection point A minus the voltage of the detection point C, and the Ubc is the voltage of the detection point B minus the voltage of the detection point C. At this time, under the condition that the overvoltage shutdown module and the undervoltage shutdown module can be normally conducted, the voltages of the three points A, B, C are the same, so that whether the voltages of Uab, uac and Ubc are equal to 0V or not can be judged, if any voltage is not equal to 0V, the fault is open, and the processing unit sends out open fault information.

Referring to the circuit state diagram shown in fig. 2 for judging whether the overvoltage shutdown module and the undervoltage shutdown module are in short circuit, the overvoltage shutdown module and the undervoltage shutdown module are controlled to be disconnected, the step-down module is controlled to work, and the detection switch is controlled to be turned on; voltages of the detection points A, B and C are detected, and voltages of Uab, uac and Ubc are calculated. At this time, in the case that both the overvoltage shutdown module and the undervoltage shutdown module can be normally turned off, both points a and B should be 2 volts higher than point B. So it can judge if the voltage of Uac is greater than or equal to 2V, if yes, there is no fault, otherwise the overvoltage shutdown module shorts out the fault. And further, whether the voltage of Ubc is more than or equal to 2V can be judged, if yes, no fault exists, and otherwise, the under-voltage shutdown module is in short circuit fault.

Referring to the circuit state diagram shown in fig. 3 for judging whether the overvoltage shutdown module is broken or not, the overvoltage shutdown module is controlled to be turned on, the undervoltage shutdown module and the detection switch are controlled to be turned off, and the voltage reduction module works; detecting voltages of the detection points A, B and C, and calculating voltages of Uba and Uca; the Uba is the voltage of the detection point B minus the voltage of the detection point A, and the Uca is the voltage of the detection point C minus the voltage of the detection point A; judging that the voltage of Uba is more than or equal to 2V and the voltage of Uca is equal to 0V, and if the voltage is not more than 2V, no fault exists; if the voltage of Uba is less than 2V or the voltage of Uca is not equal to 0V, the overvoltage shutdown module breaks down.

Referring to the circuit state diagram of judging whether the under-voltage turn-off module is broken or not shown in fig. 4, the over-voltage turn-off module and the detection switch are controlled to be turned off, the under-voltage turn-off module is controlled to be turned on, and the voltage reduction module works; detecting voltages of a detection point A, a detection point B and a detection point C, and calculating voltages of Uab and Ucb; the Ucb is the voltage of the detection point C minus the voltage of the detection point B; judging whether the voltage of Uab is more than or equal to 2V and the voltage of Ucb is equal to 0V, if so, no fault exists; if the voltage of Uab is smaller than 2V or the voltage of Ucb is not equal to 0V, the under-voltage shutdown module breaks down.

The above examples are illustrative only and are not intended to be limiting. Any equivalent modifications or variations to the present application without departing from the spirit and scope of the present application are intended to be included within the scope of the claims of the present application.

Fig. 1-5 are only used to illustrate embodiments of the present utility model and should not be used to limit the scope of the utility model.

Claims (5)

1. The utility model provides a DCDC converter excessive pressure and undervoltage module fault detection circuit, includes direct current connector, excessive pressure shutoff module, undervoltage shutoff module, first battery and the load of establishing ties in proper order, its characterized in that still includes: the device comprises a direct current connector, an overvoltage shutdown module, a load connection line, a detection point A, a detection point C, a detection point B and a processing unit, wherein the detection point A is arranged on the connection line of the direct current connector and the overvoltage shutdown module, the detection point C is arranged on the connection line of the overvoltage shutdown module and the undervoltage shutdown module, the detection point B is arranged on the connection line of the undervoltage shutdown module, the first battery and the load connection line, the on-off of a switch in the overvoltage shutdown module and the undervoltage shutdown module is controlled, the voltage of the detection point A, the detection point B and the detection point C is detected, and whether the overvoltage shutdown module and the undervoltage shutdown module are normal or not is judged according to the detected voltage.

2. The DCDC converter overvoltage and undervoltage module failure detection circuit of claim 1, further comprising: a step-down module and a detection switch; the first end of the voltage reduction module is connected with the detection point C, the second end of the voltage reduction module is connected with the detection point B and the third end of the detection switch, and the fourth end of the detection switch is connected with the detection point A; the fifth end of the detection switch and the sixth end of the voltage reduction module are both connected with the processing unit for controlling the on-off of the detection switch and controlling the voltage of the first battery to be reduced by N volts and then sent to the detection point C.

3. The DCDC converter overvoltage and undervoltage module failure detection circuit of claim 1, wherein the voltage of the first battery is dc 12V.

4. The DCDC converter overvoltage and undervoltage module failure detection circuit of claim 2, wherein the N volts is 2V.

5. The DCDC converter overvoltage and undervoltage module fault detection circuit of claim 2, wherein the detection switch includes a relay switch.