Insulation detection circuit and method

Abstract

This invention provides an insulation detection circuit and method. The circuit includes a processor, a positive sampling unit, a negative sampling unit, and a signal injection unit. The positive sampling unit outputs a first sampling signal. A first terminal of the positive sampling unit is connected to the positive terminal of a power battery pack, and a second terminal is connected to a reference ground. A first terminal of the negative sampling unit is connected to the negative terminal of the power battery pack, and a second terminal is connected to a reference ground. A first terminal of the signal injection unit is connected to the reference ground, and a second terminal is connected to the vehicle body ground. The processor is configured to determine the insulation detection method to be used based on the vehicle's operating conditions, and based on the determined insulation detection method, performs circuit self-testing and insulation resistance detection based on the real-time sampled first and second sampling signals, thereby improving the effectiveness of vehicle insulation detection.

Description

Technical Field

[0001] This invention relates to the field of battery management technology, and more specifically, to an insulation detection circuit and method. Background Technology

[0002] With the development of technology, battery systems have been widely used in the automotive and energy storage fields. Electric vehicle batteries require good insulation performance. During vehicle operation, they will encounter many complex situations, such as water wading, collisions, vibrations, or high temperature and humidity environments. Under these environments, insulation materials are prone to aging or other conditions that affect insulation performance.

[0003] Currently, electric vehicles operate at voltages of several hundred volts. To improve fast charging speeds, mid-to-high-end models are increasingly moving towards 800V or even higher voltage levels. However, the safe voltage for the human body is 60V. As voltage levels continue to rise, improving the accuracy of insulation warnings in electric vehicles is crucial for passengers. Summary of the Invention

[0004] The problem addressed by this invention is how to improve the effectiveness of vehicle insulation testing.

[0005] To address the above problems, the present invention provides an insulation detection circuit, comprising a processor, a positive sampling unit, a negative sampling unit, and a signal injection unit;

[0006] The positive sampling unit is used to output a first sampling signal; the first end of the positive sampling unit is used to connect to the positive terminal of the power battery pack, and the second end of the positive sampling module is used to connect to a reference ground.

[0007] The negative electrode sampling unit is used to output a second sampling signal; the first end of the negative electrode sampling unit is used to connect to the negative electrode of the power battery pack, and the second end of the negative electrode sampling unit is used to connect to the reference ground;

[0008] The first end of the signal injection unit is connected to the reference ground, and the second end of the signal injection unit is connected to the vehicle body ground; the signal injection unit is used to cooperate with the processor to inject a square wave signal into the circuit where the signal injection unit is located.

[0009] The processor is configured to determine the insulation detection method to be used based on the vehicle's operating conditions, and based on the determined insulation detection method, perform circuit self-testing and insulation resistance detection based on the real-time sampled first and second sampled signals.

[0010] Optionally, the processor is specifically configured to, in response to detecting an abnormal output voltage of the power battery pack before the power battery pack is connected to the vehicle load system, perform circuit self-test and insulation resistance detection based on an active insulation detection method, according to a first sampling signal and a second sampling signal sampled in real time;

[0011] The processor is also specifically configured to, in response to detecting that the output voltage of the power battery pack is not abnormal before the power battery pack is connected to the vehicle load system, perform circuit self-test and insulation resistance detection based on the passive insulation detection method and according to the real-time sampled first and second sampled signals.

[0012] The processor is also specifically configured to, after the power battery pack is connected to the vehicle load system, calculate the parallel value of the insulation resistance based on the first and second sampling signals sampled in real time using an active insulation detection method and perform circuit self-test.

[0013] Optionally, it further includes a voltage divider unit, which is used to output the voltage divider signal of the power battery pack; the first end of the voltage divider unit is used to connect to the positive terminal of the power battery pack, and the second end of the voltage divider unit is used to connect to the negative terminal of the power battery pack.

[0014] The processor is also configured to determine whether the output voltage of the power battery pack is abnormal based on the voltage divider signal of the power battery pack.

[0015] Optionally, the positive electrode sampling unit includes a first voltage sampling point, a first switch, and a first resistor, a second resistor, and a third resistor connected in series; the first resistor is used to connect to the positive electrode of the power battery pack; the third resistor is used to connect to the reference ground; the first switch is connected in parallel with the second resistor; the first voltage sampling point is located between the second resistor and the third resistor.

[0016] The negative electrode sampling unit further includes a second voltage sampling point, a second switch, and a fourth resistor, a fifth resistor, and a sixth resistor connected in series. The sixth resistor is used to connect to the negative electrode of the power battery pack. The fourth resistor is used to connect to the reference ground. The second switch is connected in parallel with the fifth resistor. The second voltage sampling point is located between the fourth resistor and the fifth resistor.

[0017] Optionally, the signal injection unit includes a positive and negative composite square wave generator, a third switch, and a fourth switch. The first end of the fourth switch is connected to the second end of the third switch; the second end of the fourth switch is connected to the vehicle body ground; the positive and negative composite square wave generator is connected in parallel with the fourth switch; and the first end of the third switch is used to connect to the reference ground.

[0018] On the other hand, the present invention also proposes an insulation detection method for use in an insulation detection circuit, the insulation detection method comprising:

[0019] The insulation testing method is determined based on the vehicle's operating conditions, and based on the determined insulation testing method, circuit self-testing and insulation resistance testing are performed based on the first and second sampling signals sampled in real time.

[0020] Optionally, the positive sampling unit of the insulation detection circuit includes a first voltage sampling point, a first switch, and a first resistor, a second resistor, and a third resistor connected in series; the first resistor is used to connect to the positive terminal of the power battery pack; the third resistor is used to connect to a reference ground; the first switch is connected in parallel with the second resistor; the first voltage sampling point is located between the second resistor and the third resistor.

[0021] The negative sampling unit of the insulation detection circuit further includes a second voltage sampling point, a second switch, and a fourth resistor, a fifth resistor, and a sixth resistor connected in series. The sixth resistor is used to connect to the negative terminal of the power battery pack. The fourth resistor is used to connect to the reference ground. The second switch is connected in parallel with the fifth resistor. The second voltage sampling point is located between the fourth resistor and the fifth resistor.

[0022] The signal injection unit of the insulation detection circuit includes a positive and negative composite square wave generator, a third switch, and a fourth switch. The first terminal of the fourth switch is connected to the second terminal of the third switch; the second terminal of the fourth switch is connected to the vehicle body ground; the positive and negative composite square wave generator is connected in parallel with the fourth switch; the first terminal of the third switch is used to connect to the reference ground.

[0023] The process of determining the insulation testing method based on the vehicle's operating conditions, and performing circuit self-testing and insulation resistance testing based on the determined insulation testing method and the real-time sampled first and second sampling signals, includes:

[0024] In response to detecting an abnormal output voltage of the power battery pack before it is connected to the vehicle load system, the circuit self-test and insulation resistance detection are performed based on the active insulation detection method, according to the real-time sampled first and second sampled signals.

[0025] In response to the detection that the output voltage of the power battery pack is not abnormal before the power battery pack is connected to the vehicle load system, the circuit self-test and insulation resistance detection are performed based on the passive insulation detection method according to the first and second sampling signals sampled in real time.

[0026] After the power battery pack is connected to the vehicle load system, the parallel value of the insulation resistance is calculated based on the active insulation detection method according to the first and second sampling signals sampled in real time, and the circuit self-test is performed.

[0027] Optionally, in response to detecting an abnormal output voltage of the power battery pack before it is connected to the vehicle load system, the method of performing circuit self-testing and insulation resistance detection based on an active insulation detection method and real-time sampled first and second sampling signals includes:

[0028] In response to detecting an abnormal output voltage of the power battery pack before it is connected to the vehicle load system, the third switch is closed.

[0029] Disconnect the first switch, the second switch, and the fourth switch to control the positive and negative composite square wave generator to generate a square wave signal and collect the voltage at the first voltage sampling point, denoted as U. +1 And the voltage at the second voltage sampling point is collected, denoted as U. -1 ;

[0030] Close the first and second switches, open the fourth switch, control the positive and negative composite square wave generator to generate a square wave signal, and collect the voltage at the first voltage sampling point, denoted as U. +2 And the voltage at the second voltage sampling point is collected, denoted as U. -2 ;

[0031] Will U +1 U -1 Substitute U into the first preset formula, +2 and U -2 Substitute into the second preset formula to calculate the insulation resistance;

[0032] Determine whether the first set of equations is true;

[0033] In response to the determination that the first set of equations is true, it is determined that the insulation detection circuit is not faulty;

[0034] In response to the determination that the first set of equations is not true, it is determined that the insulation detection circuit is faulty;

[0035] The first set of equations includes:

[0036] and

[0037]

[0038] Optionally, in response to detecting that the output voltage of the power battery pack is not abnormal before the power battery pack is connected to the vehicle load system, the circuit self-test and insulation resistance detection are performed based on the passive insulation detection method according to the real-time sampled first and second sampled signals, including:

[0039] In response to the detection that there is no abnormality in the output voltage of the power battery pack before it is connected to the vehicle load system, the third switch and the fourth switch are closed.

[0040] Close the first switch, open the second switch, and collect the voltage at the first voltage sampling point, denoted as U. +1 And the voltage at the second voltage sampling point is collected, denoted as U. -1 ;

[0041] Disconnect the first switch, close the second switch, and collect the voltage at the first voltage sampling point, denoted as U. +2 And the voltage at the second voltage sampling point is collected, denoted as U. -2 ;

[0042] Will U +1 U -1 Substituting into the third preset formula, U +2 and U -2 Substitute into the fourth preset formula to calculate the insulation resistance;

[0043] Determine whether the second set of equations is true;

[0044] In response to the determination that the second set of equations is true, it is determined that the insulation detection circuit is not faulty;

[0045] In response to the determination that the second set of equations is not true, it is determined that the insulation detection circuit is faulty;

[0046] The second set of equations includes:

[0047] and

[0048]

[0049] Optionally, after the power battery pack is connected to the vehicle load system, based on the active insulation detection method, the parallel value of the insulation resistance is calculated according to the first and second sampling signals sampled in real time, and a circuit self-test is performed, including:

[0050] After the power battery pack is connected to the vehicle load system, the first switch, the second switch, and the third switch are closed, and the fourth switch is opened.

[0051] The positive and negative composite square wave generator is controlled to generate a positive square wave signal, and the voltage at the first voltage sampling point is collected and denoted as U. +1 And the voltage at the second voltage sampling point is collected, denoted as U. -1 ;

[0052] The positive and negative composite square wave generator is controlled to generate a negative square wave signal, and the voltage at the first voltage sampling point is collected and denoted as U. +2 And the voltage at the second voltage sampling point is collected, denoted as U. -2 ;

[0053] Will U +1 U -1 Substituting into the fifth preset formula, U +2 and U -2 Substitute into the sixth preset formula to calculate the parallel value of the insulation resistance;

[0054] Determine whether the third equation is true;

[0055] In response to the determination that the third equation is true, it is determined that the insulation detection circuit is not faulty;

[0056] In response to the determination that the third equation is not true, it is determined that the insulation detection circuit is faulty;

[0057] The third equation is:

[0058] U +1 -U +2 =U -1 -U -2 .

[0059] Compared to existing technologies, this invention outputs first and second sampling signals through a positive sampling unit and a negative sampling unit, respectively, and injects a square wave signal through a signal injection unit. This enables the processor to complete the self-test process of the insulation sampling circuit during insulation resistance detection, achieving rapid and effective insulation resistance detection. Since different insulation detection methods have different detection accuracy and effects under different operating conditions, this invention can select different insulation detection methods according to the operating conditions of the vehicle, and perform circuit self-test and insulation resistance detection based on the sampling signals, ensuring improved effectiveness of vehicle insulation detection. Attached Figure Description

[0060] Figure 1 This is a system block diagram of an insulation detection circuit provided in an embodiment of the present invention;

[0061] Figure 2 This is a schematic diagram of the insulation detection circuit provided in an embodiment of the present invention;

[0062] Figure 3This is a schematic diagram of the insulation detection circuit provided in another embodiment of the present invention;

[0063] Figure 4 A schematic diagram of the equivalent circuit of the insulation detection circuit under the first vehicle operating condition, provided in another embodiment of the present invention;

[0064] Figure 5 This is a schematic diagram of the equivalent circuit of the insulation detection circuit in the third vehicle operating condition according to an embodiment of the present invention.

[0065] Figure 6 This is a schematic flowchart of the insulation detection method according to an embodiment of the present invention;

[0066] Figure 7 This is a detailed flowchart of step S100 of the insulation detection method according to an embodiment of the present invention.

[0067] Figure 8 This is a detailed flowchart of step S200 of the insulation detection method according to an embodiment of the present invention. Detailed Implementation

[0068] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Although some embodiments of the present invention are shown in the drawings, it should be understood that the present invention can be implemented in various forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of the present invention. It should be understood that the accompanying drawings and embodiments of the present invention are for illustrative purposes only and are not intended to limit the scope of protection of the present invention.

[0069] It should be understood that the various steps described in the method embodiments of the present invention may be performed in different orders and / or in parallel. Furthermore, the method embodiments may include additional steps and / or omit the steps shown. The scope of the present invention is not limited in this respect.

[0070] The term "comprising" and its variations as used herein are open-ended, meaning "including but not limited to". The term "based on" means "at least partially based on". The term "one embodiment" means "at least one embodiment"; the term "another embodiment" means "at least one additional embodiment"; the term "some embodiments" means "at least some embodiments"; the term "optionally" means "optional embodiments". Definitions of other terms will be given in the following description. It should be noted that the concepts of "first", "second", etc., mentioned in this invention are used only to distinguish different devices, modules, or units, and are not intended to limit the order of functions performed by these devices, modules, or units or their interdependencies.

[0071] It should be noted that the terms "a" and "a plurality of" used in this invention are illustrative rather than restrictive. Those skilled in the art should understand that, unless otherwise expressly indicated in the context, they should be understood as "one or more".

[0072] like Figure 1 As shown, an embodiment of the present invention provides an insulation detection circuit, which includes a processor, a positive sampling unit, a negative sampling unit, and a signal injection unit.

[0073] The positive electrode sampling unit is used to output a first sampling signal. The first end of the positive electrode sampling unit is used to connect to the positive electrode of the power battery pack, and the second end of the positive electrode sampling module is used to connect to a reference ground.

[0074] The negative electrode sampling unit is used to output a second sampling signal. The first end of the negative electrode sampling unit is used to connect to the negative electrode of the power battery pack, and the second end of the negative electrode sampling unit is used to connect to the reference ground.

[0075] The first end of the signal injection unit is connected to the reference ground, and the second end of the signal injection unit is connected to the vehicle body ground. The signal injection unit is used to cooperate with the processor to inject a square wave signal into the circuit where the signal injection unit is located.

[0076] The processor is configured to determine the insulation detection method to be used based on the vehicle's operating conditions, and based on the determined insulation detection method, perform circuit self-testing and insulation resistance detection based on the real-time sampled first and second sampled signals.

[0077] A battery pack (PACK) refers to a battery pack in a vehicle that consists of multiple power batteries.

[0078] In one embodiment, when no insulation test is performed, the insulation test circuit is disconnected from the vehicle body ground (i.e., Figure 2 The connection of CHASSIS shown in the figure.

[0079] Compared to existing technologies, this invention outputs first and second sampling signals through a positive sampling unit and a negative sampling unit, respectively, and injects a square wave signal through a signal injection unit. This enables the processor to complete the self-test process of the insulation sampling circuit during insulation resistance detection, achieving rapid and effective insulation resistance detection. Since different insulation detection methods have different detection accuracy and effects under different operating conditions, this invention can select different insulation detection methods according to the operating conditions of the vehicle, and perform circuit self-test and insulation resistance detection based on the sampling signals, ensuring improved effectiveness of vehicle insulation detection.

[0080] Optionally, such as Figure 4As shown, the processor is specifically configured to, in response to detecting an abnormal output voltage of the power battery pack before it is connected to the vehicle load system, perform circuit self-testing and insulation resistance detection based on an active insulation detection method, according to a first sampling signal and a second sampling signal sampled in real time.

[0081] Specifically, for vehicle operating condition one: before the system is charged with high voltage, if the PACK total voltage is abnormal (e.g., MSD not inserted, Busbar open circuit, etc.), an active insulation detection method is used to perform circuit self-test and insulation resistance test. Circuit self-testing prevents connection errors or component failures in the insulation sampling circuit within the battery management system, ensuring the normal operation of the battery management system and avoiding safety issues caused by starting the vehicle when hardware malfunctions.

[0082] The processor is also specifically configured to, in response to detecting that the output voltage of the power battery pack is not abnormal before the power battery pack is connected to the vehicle load system, perform circuit self-test and insulation resistance detection based on a passive insulation detection method, according to a first sampling signal and a second sampling signal sampled in real time.

[0083] In other words, for automotive operating condition two: before the system is under high voltage, if the PACK voltage is normal, the insulation resistance RP and RN can be tested more quickly by passively measuring the insulation resistance and performing circuit self-test.

[0084] The processor is also specifically configured to, after the power battery pack is connected to the vehicle load system, calculate the parallel value of the insulation resistance based on the first and second sampling signals sampled in real time using an active insulation detection method and perform circuit self-test.

[0085] Specifically, regarding automotive operating condition three: After an electric vehicle is connected to high voltage, during the operation of the vehicle inverter, due to the rapid switching of the inverter's internal switches, if the insulation resistance is collected using the traditional passive insulation method, the collected RP and RN values ​​are actually the resistance values ​​after being connected in parallel with the inverter system's insulation impedance, which differs significantly from the system's true insulation resistance. This embodiment of the invention, through active insulation, can accurately detect the parallel value RP / / RN of the insulation resistance to ground of all links in the high-voltage system, thus providing a more accurate characterization of the high-voltage system's insulation resistance status.

[0086] Based on the insulation detection circuit provided in this embodiment of the invention, different insulation detection methods can be flexibly combined to detect the insulation resistance under the above three automotive operating conditions and perform self-testing, resulting in better detection results.

[0087] Optionally, the insulation detection circuit further includes a voltage divider unit, which outputs a voltage divider signal from the power battery pack. A first terminal of the voltage divider unit is connected to the positive terminal of the power battery pack, and a second terminal of the voltage divider unit is connected to the negative terminal of the power battery pack.

[0088] The processor is also configured to determine whether the output voltage of the power battery pack is abnormal based on the voltage divider signal of the power battery pack.

[0089] In one alternative implementation, such as Figure 2 and Figure 3 As shown, the first capacitor Y1 and the second capacitor Y2 represent the parasitic capacitance of the power battery pack bus to ground. RP represents the insulation resistance of the power battery pack positively to ground, and RN represents the insulation resistance of the power battery pack negatively to ground. The positive sampling unit includes a first voltage sampling point U+, a first switch S1, and a first resistor R1, a second resistor R2, and a third resistor R3 connected in series. The first resistor R1 is used to connect to the positive terminal of the power battery pack. The third resistor R3 is used to connect to the reference ground GND. The first switch S1 is connected in parallel with the second resistor R2. The first voltage sampling point U+ is located between the second resistor R2 and the third resistor R3.

[0090] The negative electrode sampling unit also includes a second voltage sampling point U-, a second switch S2, and a fourth resistor R4, a fifth resistor R5, and a sixth resistor R6 connected in series. The sixth resistor R6 is used to connect to the negative terminal of the power battery pack. The fourth resistor R4 is used to connect to the reference ground GND. The second switch K2 is connected in parallel with the fifth resistor R5. The second voltage sampling point U- is located between the fourth resistor R4 and the fifth resistor R5.

[0091] The signal injection unit includes a positive and negative composite square wave generator U0, a third switch S3, and a fourth switch S4. The first terminal of the fourth switch S4 is connected to the second terminal of the third switch S3. The second terminal of the fourth switch S4 is connected to the vehicle body ground CHSSIS. The positive and negative composite square wave generator U0 is connected in parallel with the fourth switch S4. The first terminal of the third switch S3 is used to connect to the reference ground GND.

[0092] To meet the withstand voltage test requirements of 2U+1000V, a third switch is installed in the circuit. During the withstand voltage test and in the BMS sleep state, the third switch is open. When the BMS system is operating normally, the third switch remains normally closed.

[0093] The voltage divider unit includes a first voltage divider resistor R7, a second voltage divider resistor R8, and a third voltage sampling point UB disposed between the first voltage divider resistor R7 and the second voltage divider resistor R8. The first voltage divider resistor R7 is connected to the positive terminal of the power battery pack PACK. The second voltage divider resistor R8 is used to connect to the negative terminal of the power battery pack PACK; the third voltage sampling point UB is used to output the voltage divider signal of the power battery pack PACK.

[0094] On the other hand, such as Figure 5 , Figure 6 As shown, this embodiment of the invention also provides an insulation detection method, applied to the insulation detection circuit described above, the insulation detection method comprising:

[0095] The insulation testing method is determined based on the vehicle's operating conditions, and based on the determined insulation testing method, circuit self-testing and insulation resistance testing are performed based on the first and second sampling signals sampled in real time.

[0096] Furthermore, the positive sampling unit of the insulation detection circuit includes a first voltage sampling point, a first switch, and a first resistor, a second resistor, and a third resistor connected in series. The first resistor is used to connect to the positive terminal of the power battery pack. The third resistor is used to connect to a reference ground. The first switch is connected in parallel with the second resistor. The first voltage sampling point is located between the second resistor and the first resistor.

[0097] The negative sampling unit of the insulation detection circuit further includes a second voltage sampling point, a second switch, and a fourth, fifth, and sixth resistor connected in series. The sixth resistor is used to connect to the negative terminal of the power battery pack. The fourth resistor is used to connect to the reference ground. The second switch is connected in parallel with the fifth resistor. The second voltage sampling point is located between the fourth and fifth resistors.

[0098] The signal injection unit of the insulation detection circuit includes a positive-negative composite square wave generator, a third switch, and a fourth switch. The first terminal of the fourth switch is connected to the second terminal of the third switch. The second terminal of the fourth switch is connected to the vehicle body ground. The positive-negative composite square wave generator is connected in parallel with the fourth switch. The first terminal of the third switch is used to connect to the reference ground.

[0099] The insulation testing method includes:

[0100] Step S100: In response to detecting an abnormal output voltage of the power battery pack before it is connected to the vehicle load system, a circuit self-test and insulation resistance detection are performed based on the active insulation detection method, according to the first and second sampling signals sampled in real time.

[0101] Step S200: In response to the detection that the output voltage of the power battery pack is not abnormal before the power battery pack is connected to the vehicle load system, circuit self-test and insulation resistance detection are performed based on the passive insulation detection method according to the first sampling signal and the second sampling signal sampled in real time.

[0102] Step S300: After the power battery pack is connected to the vehicle load system, the parallel value of the insulation resistance is calculated based on the active insulation detection method according to the first and second sampling signals sampled in real time, and a circuit self-test is performed.

[0103] Specifically, in combination Figure 7 As shown, in response to detecting an abnormal output voltage of the power battery pack before it is connected to the vehicle load system, the method, based on active insulation detection, performs circuit self-testing and insulation resistance detection according to the real-time sampled first and second sampling signals, including:

[0104] Step S110: In response to detecting an abnormal output voltage of the power battery pack before it is connected to the vehicle load system, the third switch is closed.

[0105] Step S120: Disconnect the first switch, the second switch, and the fourth switch; control the positive and negative composite square wave generator to generate a square wave signal; and collect the voltage at the first voltage sampling point, denoted as U. +1 And the voltage at the second voltage sampling point is collected, denoted as U. -1 .

[0106] Step S130: Close the first switch and the second switch, open the fourth switch, control the positive and negative composite square wave generator to generate a square wave signal, and collect the voltage at the first voltage sampling point, denoted as U. +2 And the voltage at the second voltage sampling point is collected, denoted as U. -2 It should be noted that the polarity of this square wave signal is consistent with the polarity of the square wave signal in the previous step.

[0107] Step S140, U +1 U -1 Substitute U into the first preset formula, +2 and U -2 Substitute into the second preset formula to calculate the insulation resistances RN and RP.

[0108] Specifically, the first preset formula is:

[0109]

[0110]

[0111] The second preset formula is:

[0112]

[0113]

[0114] Step S150: Determine whether the first set of equations is true.

[0115] Step S160: In response to determining that the first set of equations is true, it is determined that the insulation detection circuit is not faulty.

[0116] Step S170: In response to the determination that the first set of equations is not true, it is determined that the insulation detection circuit has a fault.

[0117] The first set of equations includes:

[0118] and

[0119]

[0120] like If true, then the RP calculated above is considered valid; if... If the above calculation of RN is valid, then the insulation detection circuit is determined to be fault-free, thus completing the circuit self-test.

[0121] Specifically, such as Figure 8 As shown, in response to detecting that the output voltage of the power battery pack is not abnormal before the power battery pack is connected to the vehicle load system, the circuit self-test and insulation resistance detection are performed based on the passive insulation detection method according to the real-time sampled first and second sampled signals, including:

[0122] Step S210: In response to detecting that the output voltage of the power battery pack is not abnormal before the power battery pack is connected to the vehicle load system, the third switch and the fourth switch are closed.

[0123] Step S220: Close the first switch, open the second switch, and collect the voltage at the first voltage sampling point, denoted as U. +1 And the voltage at the second voltage sampling point is collected, denoted as U. -1 .

[0124] Step S230: Disconnect the first switch, close the second switch, and collect the voltage at the first voltage sampling point, denoted as U. +2 And the voltage at the second voltage sampling point is collected, denoted as U. -2 .

[0125] Step S240, U +1 U -1 Substituting into the third preset formula, U +2 and U -2 Substitute into the fourth preset formula to calculate the insulation resistance.

[0126] The third preset formula is:

[0127]

[0128]

[0129] The fourth preset formula is:

[0130]

[0131]

[0132] Step S250: Determine whether the second set of equations is true.

[0133] Step S260: In response to determining that the second set of equations is true, it is determined that the insulation detection circuit is not faulty.

[0134] Step S270: In response to the determination that the second set of equations is not true, it is determined that the insulation detection circuit has a fault.

[0135] The second set of equations includes:

[0136] and

[0137]

[0138] like If true, then the sampled value U is determined. +1 and U -1 The validity; if If true, then the sampled value U is determined. +2 and U -2 The effectiveness of the insulation detection circuit is determined, thus confirming that there is no fault in the insulation detection circuit, and the circuit self-test is completed.

[0139] Specifically, in combination Figure 5 As shown, after the power battery pack is connected to the vehicle load system, based on the active insulation detection method, the parallel value of the insulation resistance is calculated according to the first and second sampling signals sampled in real time, and a circuit self-test is performed, including:

[0140] After the power battery pack is connected to the vehicle load system, the first switch, the second switch, and the third switch are closed, and the fourth switch is opened.

[0141] The positive and negative composite square wave generator is controlled to generate a positive square wave signal, and the voltage at the first voltage sampling point is collected and denoted as U. +1 And the voltage at the second voltage sampling point is collected, denoted as U. -1 .

[0142] The positive and negative composite square wave generator is controlled to generate a negative square wave signal, and the voltage at the first voltage sampling point is collected and denoted as U. +2 And the voltage at the second voltage sampling point is collected, denoted as U. -2 .

[0143] Will U +1 U -1 Substituting into the fifth preset formula, U +2 and U -2 Substitute into the sixth preset formula to calculate the insulation resistance.

[0144] The fifth preset formula is:

[0145]

[0146]

[0147] The sixth preset formula is:

[0148]

[0149]

[0150] Specifically, by simultaneously applying the fifth and sixth presupposed formulas, we obtain:

[0151]

[0152]

[0153] because Except for RP / / RN, which is an unknown quantity, all other quantities in the formula are known quantities, so the corresponding insulation resistance value RP / / RN can be calculated.

[0154] Determine whether the third equation is true.

[0155] In response to the determination that the third equation is true, it is determined that the insulation detection circuit is not faulty.

[0156] In response to the determination that the third equation is not true, it is determined that the insulation detection circuit is faulty.

[0157] The third equation is:

[0158] U +1 -U +2 =U-1 -U -2 .

[0159] Under normal conditions, in a square wave cycle, RP / / RN is a constant value, and the equation U should hold. +1 -U +2 =U -1 -U -2 When the third equation is true, it indicates that the insulation detection circuit is connected normally; otherwise, it indicates that the acquisition circuit is abnormal, thus achieving circuit self-testing.

[0160] Optionally, the insulation detection circuit further includes a voltage divider unit. The voltage divider unit includes a first voltage divider resistor R7, a second voltage divider resistor R8, and a third voltage sampling point UB disposed between the first voltage divider resistor R7 and the second voltage divider resistor R8. The first voltage divider resistor R7 is connected to the positive terminal of the power battery pack PACK. The second voltage divider resistor R8 is connected to the negative terminal of the power battery pack PACK. The third voltage sampling point UB is used to output the voltage divider signal of the power battery pack PACK.

[0161] The method for determining whether the power battery pack is connected to the insulation detection circuit includes:

[0162] Determine whether the first equation holds true based on the voltage divider signal.

[0163] In response to the determination that the first equation is true, it is determined that the power battery pack is connected to the insulation detection circuit.

[0164] In response to the determination that the first equation is not true, it is determined that the power battery pack is disconnected from the insulation detection circuit.

[0165] The first equation is:

[0166]

[0167] Wherein, UPACK is the theoretical voltage value of the power battery pack; UB' is the voltage divider signal of the power battery pack PACK acquired through the third voltage sampling point UB.

[0168] By measuring the voltage drop across resistors R7 and R8, it is possible to determine if there are any abnormalities in the voltage of the power battery pack, so that faults can be identified and addressed promptly.

[0169] Another embodiment of the present invention provides an electronic device including a memory and a processor. The memory is used to store a computer program. The processor, when executing the computer program, implements the insulation detection method described above.

[0170] Another embodiment of the present invention provides a computer-readable storage medium storing a computer program, which, when executed by a processor, implements the insulation detection method described above.

[0171] The present invention will now describe electronic devices that can serve as servers or clients of the present invention, which are examples of hardware devices that can be applied to various aspects of the present invention. Electronic devices are intended to represent various forms of digital electronic computer devices, such as laptop computers, desktop computers, workstations, personal digital assistants, servers, blade servers, mainframe computers, and other suitable computers. Electronic devices can also represent various forms of mobile devices, such as personal digital processors, cellular phones, smartphones, wearable devices, and other similar computing devices. The components shown herein, their connections and relationships, and their functions are merely illustrative and are not intended to limit the implementation of the invention described and / or claimed herein.

[0172] Electronic devices include a computing unit that can perform various appropriate actions and processes based on a computer program stored in read-only memory (ROM) or loaded from a storage unit into random access memory (RAM). The RAM can also store various programs and data required for device operation. The computing unit, ROM, and RAM are interconnected via a bus. Input / output (I / O) interfaces are also connected to the bus.

[0173] Computer systems can include clients and servers. Clients and servers are generally located far apart and typically interact through communication networks. Client-server relationships are created by computer programs running on the respective computers and having a client-server relationship with each other.

[0174] Those skilled in the art will understand that all or part of the processes in the above embodiments can be implemented by a computer program instructing related hardware. The program can be stored in a computer-readable storage medium, and when executed, it can include the processes of the embodiments of the above methods. The storage medium can be a magnetic disk, optical disk, read-only memory (ROM), or random access memory (RAM), etc. In this application, the units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of the embodiments of the present invention according to actual needs. Furthermore, the functional units in the various embodiments of the present invention can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated units can be implemented in hardware or as software functional units.

[0175] While the disclosure is as stated above, its scope of protection is not limited thereto. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of this disclosure, and all such changes and modifications will fall within the protection scope of this invention.

Claims

1. An insulation detection circuit, characterized in that, It includes a processor, a positive sampling unit, a negative sampling unit, and a signal injection unit; The positive electrode sampling unit is used to output a first sampling signal; the first end of the positive electrode sampling unit is used to connect to the positive electrode of the power battery pack, and the second end of the positive electrode sampling unit is used to connect to a reference ground; The negative electrode sampling unit is used to output a second sampling signal; the first end of the negative electrode sampling unit is used to connect to the negative electrode of the power battery pack, and the second end of the negative electrode sampling unit is used to connect to the reference ground; The first end of the signal injection unit is connected to the reference ground, and the second end of the signal injection unit is connected to the vehicle body ground; the signal injection unit is used to cooperate with the processor to inject a square wave signal into the circuit where the signal injection unit is located. The processor is configured to determine the insulation detection method to be used based on the vehicle's operating conditions, and based on the determined insulation detection method, perform circuit self-testing and insulation resistance detection according to the real-time sampled first and second sampled signals. The positive electrode sampling unit includes a first voltage sampling point, a first switch, and a first resistor, a second resistor, and a third resistor connected in series. The first resistor is used to connect to the positive electrode of the power battery pack. The third resistor is used to connect to the reference ground. The first switch is connected in parallel with the second resistor. The first voltage sampling point is located between the second resistor and the third resistor. The negative electrode sampling unit further includes a second voltage sampling point, a second switch, and a fourth resistor, a fifth resistor, and a sixth resistor connected in series. The sixth resistor is used to connect to the negative electrode of the power battery pack. The fourth resistor is used to connect to the reference ground. The second switch is connected in parallel with the fifth resistor. The second voltage sampling point is located between the fourth resistor and the fifth resistor.

2. The insulation detection circuit according to claim 1, characterized in that, The processor is specifically configured to, in response to detecting an abnormal output voltage of the power battery pack before the power battery pack is connected to the vehicle load system, perform circuit self-testing and insulation resistance detection based on an active insulation detection method, according to a first sampling signal and a second sampling signal sampled in real time. The processor is also specifically configured to, in response to detecting that the output voltage of the power battery pack is not abnormal before the power battery pack is connected to the vehicle load system, perform circuit self-test and insulation resistance detection based on the passive insulation detection method and according to the real-time sampled first and second sampled signals. The processor is also specifically configured to, after the power battery pack is connected to the vehicle load system, calculate the parallel value of the insulation resistance based on the first and second sampling signals sampled in real time using an active insulation detection method and perform circuit self-test.

3. The insulation detection circuit according to claim 1, characterized in that, It also includes a voltage divider unit, which is used to output the voltage divider signal of the power battery pack; the first end of the voltage divider unit is used to connect to the positive terminal of the power battery pack, and the second end of the voltage divider unit is used to connect to the negative terminal of the power battery pack. The processor is also configured to determine whether the output voltage of the power battery pack is abnormal based on the voltage divider signal of the power battery pack.

4. The insulation detection circuit according to any one of claims 1-3, characterized in that, The signal injection unit includes a positive and negative composite square wave generator, a third switch, and a fourth switch. The first end of the fourth switch is connected to the second end of the third switch; the second end of the fourth switch is connected to the vehicle body ground; the positive and negative composite square wave generator is connected in parallel with the fourth switch; and the first end of the third switch is used to connect to the reference ground.

5. An insulation testing method, characterized in that, Based on the insulation detection circuit according to any one of claims 1-4, the insulation detection method includes: The insulation testing method is determined based on the vehicle's operating conditions, and based on the determined insulation testing method, circuit self-testing and insulation resistance testing are performed based on the first and second sampling signals sampled in real time.

6. The insulation testing method according to claim 5, characterized in that, The positive sampling unit of the insulation detection circuit includes a first voltage sampling point, a first switch, and a first resistor, a second resistor, and a third resistor connected in series. The first resistor is used to connect to the positive terminal of the power battery pack. The third resistor is used to connect to a reference ground. The first switch is connected in parallel with the second resistor. The first voltage sampling point is located between the second resistor and the third resistor. The negative sampling unit of the insulation detection circuit further includes a second voltage sampling point, a second switch, and a fourth resistor, a fifth resistor, and a sixth resistor connected in series. The sixth resistor is used to connect to the negative terminal of the power battery pack. The fourth resistor is used to connect to the reference ground. The second switch is connected in parallel with the fifth resistor. The second voltage sampling point is located between the fourth resistor and the fifth resistor. The signal injection unit of the insulation detection circuit includes a positive and negative composite square wave generator, a third switch, and a fourth switch. The first terminal of the fourth switch is connected to the second terminal of the third switch; the second terminal of the fourth switch is connected to the vehicle body ground; the positive and negative composite square wave generator is connected in parallel with the fourth switch; the first terminal of the third switch is used to connect to the reference ground. The process of determining the insulation testing method based on the vehicle's operating conditions, and performing circuit self-testing and insulation resistance testing based on the determined insulation testing method and the real-time sampled first and second sampling signals, includes: In response to detecting an abnormal output voltage of the power battery pack before it is connected to the vehicle load system, the circuit self-test and insulation resistance detection are performed based on the active insulation detection method, according to the real-time sampled first and second sampled signals. In response to the detection that the output voltage of the power battery pack is not abnormal before the power battery pack is connected to the vehicle load system, the circuit self-test and insulation resistance detection are performed based on the passive insulation detection method according to the first and second sampling signals sampled in real time. After the power battery pack is connected to the vehicle load system, the parallel value of the insulation resistance is calculated based on the active insulation detection method according to the first and second sampling signals sampled in real time, and the circuit self-test is performed.

7. The insulation testing method according to claim 6, characterized in that, The response to detecting an abnormal output voltage of the power battery pack before it is connected to the vehicle load system includes, based on an active insulation detection method, circuit self-testing and insulation resistance detection based on real-time sampled first and second sampling signals, including: In response to detecting an abnormal output voltage of the power battery pack before it is connected to the vehicle load system, the third switch is closed. Disconnect the first switch, the second switch, and the fourth switch to control the positive and negative composite square wave generator to generate a square wave signal, and collect the voltage at the first voltage sampling point, denoted as . And the voltage of the second voltage sampling point is collected, denoted as ; Close the first and second switches, open the fourth switch, control the positive and negative composite square wave generator to generate a square wave signal, and collect the voltage at the first voltage sampling point, denoted as . And the voltage of the second voltage sampling point is collected, denoted as ; Will , Substitute into the first preset formula, and and Substitute into the second preset formula to calculate the insulation resistance; Determine whether the first set of equations is true; In response to the determination that the first set of equations is true, it is determined that the insulation detection circuit is not faulty; In response to the determination that the first set of equations is not true, it is determined that the insulation detection circuit is faulty; The first set of equations includes: ,and Wherein, R2 represents the second resistor, R3 represents the third resistor, R4 represents the fourth resistor, R5 represents the fifth resistor, and U0 represents the positive and negative composite square wave generator.

8. The insulation testing method according to claim 6, characterized in that, The response, which detects no abnormality in the output voltage of the power battery pack before it is connected to the vehicle load system, performs circuit self-testing and insulation resistance detection based on a passive insulation detection method, according to real-time sampled first and second sampling signals, including: In response to the detection that there is no abnormality in the output voltage of the power battery pack before it is connected to the vehicle load system, the third switch and the fourth switch are closed. Close the first switch, open the second switch, and collect the voltage at the first voltage sampling point, denoted as . And the voltage of the second voltage sampling point is collected, denoted as ; Disconnect the first switch, close the second switch, and collect the voltage at the first voltage sampling point, denoted as . And the voltage of the second voltage sampling point is collected, denoted as ; Will , Substituting into the third preset formula, and Substitute into the fourth preset formula to calculate the insulation resistance; Determine whether the second set of equations is true; In response to the determination that the second set of equations is true, it is determined that the insulation detection circuit is not faulty; In response to the determination that the second set of equations is not true, it is determined that the insulation detection circuit is faulty; The second set of equations includes: ,and ,in, R1 represents the theoretical voltage value of the power battery pack, R2 represents the first resistor, R3 represents the third resistor, R4 represents the fourth resistor, R5 represents the fifth resistor, and R6 represents the sixth resistor.

9. The insulation testing method according to claim 6, characterized in that, After the power battery pack is connected to the vehicle load system, based on the active insulation detection method, the parallel value of the insulation resistance is calculated according to the first and second sampling signals sampled in real time, and a circuit self-test is performed, including: After the power battery pack is connected to the vehicle load system, the first switch, the second switch, and the third switch are closed, and the fourth switch is opened. The positive and negative composite square wave generator is controlled to generate a positive square wave signal, and the voltage at the first voltage sampling point is collected and denoted as... And the voltage of the second voltage sampling point is collected, denoted as ; The positive and negative composite square wave generator is controlled to generate a negative square wave signal, and the voltage at the first voltage sampling point is collected and denoted as... And the voltage of the second voltage sampling point is collected, denoted as ; Will , Substituting into the fifth preset formula, and Substitute into the sixth preset formula to calculate the parallel value of the insulation resistance; Determine whether the third equation is true; In response to the determination that the third equation is true, it is determined that the insulation detection circuit is not faulty; In response to the determination that the third equation is not true, it is determined that the insulation detection circuit is faulty; The third equation is: 。

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