A compressor insulation resistance monitoring circuit and a compressor control method

Abstract

A compressor insulation resistance monitoring circuit includes a base unit and a single-chip microcomputer. The monitoring circuit also includes an isolation op amp unit. The base unit and the single-chip microcomputer are both connected to the isolation op amp unit, while the base unit is not electrically connected to the single-chip microcomputer. The base unit includes a first module and a second module. The first module has two terminals connected to the first port and the second port, respectively. The second module has two terminals connected to the third port and the second port, respectively. The first module has a first pressure measuring resistor, and the second module has a second pressure measuring resistor. The isolation op amp unit includes a first isolation op amp and a second isolation op amp. The two pins of the first isolation op amp are connected to the two terminals of the first pressure measuring resistor, and the two pins of the second isolation op amp are connected to the two terminals of the second pressure measuring resistor. This monitoring circuit can effectively monitor the insulation performance of the compressor.

Description

Technical Field

[0001] The present invention relates to the field of monitoring technology, and in particular to a compressor insulation resistance monitoring circuit and a compressor control method. Background Art

[0002] With the development of new energy vehicles and technological advancements, the thermal management of new energy battery packs will directly affect the performance of the entire vehicle. As the heart of the thermal management system, the compressor is of great significance to the stability of the thermal management system.

[0003] Vehicle-mounted compressors have the characteristics of high voltage, large current, and high power. If the compressor leaks electricity, it will pose a threat to the safety and reliability of the entire vehicle. Summary of the Invention

[0004] In order to monitor the insulation performance of a compressor, the technical solution of the present invention provides a compressor insulation resistance monitoring circuit.

[0005] A compressor insulation resistance monitoring circuit includes a base part and a single-chip microcomputer, wherein the monitoring circuit further includes an isolation operational amplifier part, the base part and the single-chip microcomputer are both connected to the isolation operational amplifier part, and the base part is not electrically connected to the single-chip microcomputer.

[0006] The basic part includes a first port that can be connected to the positive pole of the power supply, a second port that can be connected to the negative pole of the power supply, and a third port that can be grounded; the basic part includes a first module and a second module, the two ends of the first module are respectively connected to the first port and the second port, the two ends of the second module are respectively connected to the third port and the second port, the first module has a first pressure measuring resistor, the second module has a second pressure measuring resistor, the isolation op amp part includes a first isolation op amp and a second isolation op amp, the two pins of the first isolation op amp are connected to the two ends of the first pressure measuring resistor, and the two pins of the second isolation op amp are connected to the two ends of the second pressure measuring resistor.

[0007] This compressor insulation resistance circuit can monitor the insulation performance of the electric compressor of the automobile, thereby improving safety and reliability.

[0008] A compressor control method is also provided, the compressor control method including a method for monitoring the insulation resistance of the compressor using the compressor insulation resistance monitoring circuit as described above, the monitoring method including the following steps:

[0009] A1: The compressor is powered on;

[0010] A2: The single chip computer calculates the insulation resistance value of the positive electrode of the compressor to the ground and the insulation resistance value of the negative electrode to the ground;

[0011] A3: The single-chip computer compares the calculated positive electrode-to-ground insulation resistance value and the negative electrode-to-ground insulation resistance value with the preset minimum resistance value and the fault resistance threshold value; if either the positive electrode-to-ground insulation resistance value or the negative electrode-to-ground insulation resistance value is less than the minimum resistance, the C1 operation is performed; if both the positive electrode-to-ground insulation resistance value and the negative electrode-to-ground insulation resistance value are greater than the minimum resistance value but either the positive electrode-to-ground insulation resistance value or the negative electrode-to-ground insulation resistance value is less than the fault resistance value, the C2 operation is performed; if both the positive electrode-to-ground insulation resistance value and the negative electrode-to-ground insulation resistance value are greater than the fault resistance threshold value, the process re-enters A2;

[0012] C1: The MCU determines that it is a level 1 fault;

[0013] C2: The MCU determines it as a level 2 fault.

[0014] The provided compressor control method includes a method for monitoring the insulation resistance of the compressor, which can monitor the insulation performance of the electric compressor of the automobile and improve safety and reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a schematic diagram of an implementation of a compressor insulation resistance monitoring circuit of the present invention.

[0016] Figure 2 It is a schematic diagram of another embodiment of the compressor insulation resistance monitoring circuit of the present invention.

[0017] Figure 3 It is a schematic diagram of another embodiment of the compressor insulation resistance monitoring circuit of the present invention.

[0018] Figure 4 It is a partial flow chart of an implementation method of the compressor control method of the present invention.

[0019] Figure 5 It is a partial flow chart of another embodiment of the compressor control method of the present invention.

[0020] Figure 6 It is a partial flow chart of another embodiment of the compressor control method of the present invention. DETAILED DESCRIPTION

[0021] Specific embodiments will now be described in detail with reference to the accompanying drawings. Numerous specific details are set forth in the following detailed description for a comprehensive understanding of the present invention. However, those skilled in the art will appreciate that the specific components, devices, orientations, and features illustrated in the drawings and described herein are merely exemplary and should not be construed as limiting.

[0022] Figure 1The present invention illustrates a compressor insulation resistance monitoring circuit 10, which includes a base unit 20, a single-chip microcomputer 30, and an isolation amplifier 40. Both the base unit 20 and the single-chip microcomputer 30 are connected to the isolation amplifier 40, but the base unit 20 is not electrically connected to the single-chip microcomputer 30.

[0023] The base portion includes a first port 11, a second port 13, and a third port 12. One of the first port 11 and the third port 12 can be connected to the positive pole of a power supply, while the other can be connected to the negative pole of a power supply. In this embodiment, the first port 11 is connected to the positive pole of the power supply, while the third port 12 is connected to the negative pole of the power supply. The second port 13 can be grounded, so that the potential of the second port 13 is 0V.

[0024] The base portion 20 includes a first module 141 and a second module 142. The two ends of the first module 141 are connected to the first port 11 and the second module 142, respectively. The two ends of the second module 142 are connected to the first module 141 and the third port 12, respectively. That is, the first module 141 and the second module 142 are connected in series between the first port 11 and the third port 12. The connection point C1 between the first module 141 and the second module 142 is connected to the second port 13. The line connecting the first module 141 to the first port 11 may include a first fuse F1, the line connecting the second module 142 to the third port 12 may include a second fuse F2, and the line connecting the connection point C1 to the second port 13 may include a third electronic switch Q3.

[0025] The first module 141 includes a first pressure measuring branch and a first control branch, wherein the first pressure measuring branch is connected in parallel with the control branch. The first control branch includes a first electronic switch Q1 and a first current limiting resistor R1, wherein the first electronic switch Q1 is connected in series with the first current limiting resistor R1. The first pressure measuring branch includes a first pressure measuring resistor R5 and a first voltage dividing resistor R3, wherein the first pressure measuring resistor R5 is connected in series with the first voltage dividing resistor R3. In a specific case, the ratio of the first voltage dividing resistor R3 to the first pressure measuring resistor R5 is greater than 100, thereby reducing the voltage across the first pressure measuring resistor R5; the ratio of the current limiting resistor R1 to the first voltage dividing resistor R3 is between 0.1 and 10, which can prevent excessive current in the control branch from causing excessive energy loss.

[0026] The second module 142 includes a second pressure measuring branch and a second control branch, wherein the second pressure measuring branch is connected in parallel with the second control branch. The second control branch includes a second electronic switch Q2 and a second current limiting resistor R2, wherein the second electronic switch Q2 is connected in series with the second current limiting resistor R2. The second pressure measuring branch includes a second pressure measuring resistor R6 and a second voltage dividing resistor R4, wherein the second pressure measuring resistor R6 is connected in series with the second voltage dividing resistor R4. In a specific case, the ratio of the second voltage dividing resistor R4 to the second pressure measuring resistor R6 is greater than 100, thereby reducing the voltage across the second pressure measuring resistor R6. The ratio of the second current limiting resistor R2 to the second voltage dividing resistor R4 is between 0.1 and 10, which can prevent excessive current in the second control branch from causing excessive energy loss.

[0027] The ratio of the first pressure-measuring resistor R5 to the first voltage-dividing resistor R3 is equal to the ratio of the second pressure-measuring resistor R6 to the second voltage-dividing resistor R4. Specifically, the first pressure-measuring resistor R5 is equal to the second pressure-measuring resistor R6, and the first voltage-dividing resistor R3 is equal to the second voltage-dividing resistor R4. Of course, the first pressure-measuring resistor R5, the second pressure-measuring resistor R6, the first voltage-dividing resistor R3, and the second voltage-dividing resistor R4 may all be equal.

[0028] The arrangement of the first voltage-dividing resistor R3 and the second voltage-dividing resistor R4 can reduce the voltage across the first pressure-measuring resistor and the second pressure-measuring resistor, thereby reducing the probability of damage to the isolation operational amplifier 40 .

[0029] The first electronic switch Q1, the second electronic switch Q2, and the third electronic switch Q3 can be a relay, and in this embodiment, a reed switch, i.e., a reed relay. The first electronic switch Q1, the second electronic switch Q2, and the third electronic switch Q3 use reed switches in the base portion 20 as disconnect switches, enabling low currents to control the on / off of high currents. They offer complete physical isolation, fast response time, high voltage resistance, low breakdown resistance, high speed, long life, strong interference resistance, and low switching internal resistance.

[0030] The isolated operational amplifier section 40 includes a first isolated operational amplifier 41 and a second isolated operational amplifier 42. Each of the first and second isolated operational amplifiers 41 and 42 has four pins: IN+, IN-, OUT, and VCC. The VCC pin is connected to the vehicle's power supply VCC, which is converted from the vehicle's battery (BATT) via a linear low-dropout (LDO) converter.

[0031] Two ends of the first pressure measuring resistor R5 are respectively connected to the IN+ pin and the IN- pin of the first isolation operational amplifier, and two ends of the second pressure measuring resistor R6 are respectively connected to the IN+ pin and the IN- pin of the second isolation operational amplifier.

[0032] The microcontroller 30 employs an MCU and includes a first ADC acquisition module ADC0, a second ADC acquisition module ADC1, and at least three IO ports. The first ADC acquisition module ADC0 is connected to the voltage output pin OUT of the first isolation op amp 41 to acquire the voltage U+ of the compressor's positive terminal relative to ground. The second ADC acquisition module ADC1 is connected to the voltage output pin OUT of the second isolation op amp 42 to acquire the voltage U- of the compressor's negative terminal relative to ground. The three IO ports of the microcontroller 30 are connected to the control pins of the first, second, and third electronic switches Q1, Q2, and Q3, respectively, and the switching states of the first, second, and third electronic switches Q1, Q2, and Q3 are controlled through the IO ports.

[0033] Providing an isolation amplifier part 40 between the base part 20 and the single chip microcomputer 30 can completely isolate the high and low voltages of the system, thereby ensuring the safety and anti-interference performance of the system.

[0034] The compressor insulation resistance monitoring circuit 10 can be equipped with different types of vehicle-mounted electric compressors and has high monitoring accuracy.

[0035] In another embodiment, the second module 142 may not be provided with a second control branch, such as Figure 2 shown.

[0036] In another embodiment, the line connecting the connection point C1 to the second port 13 may not include the third electronic switch Q3. Figure 3 shown.

[0037] Some compressor control methods include a method for detecting the insulation resistance of the compressor. The compressor insulation resistance monitoring circuit 10 can be used to monitor the insulation resistance of the compressor (the compressor insulation resistance includes the insulation resistance value of the positive electrode to the ground and the insulation resistance value of the negative electrode to the ground). The first port 11 is connected to the positive electrode of the compressor, the third port 12 is connected to the negative electrode of the compressor, and the second port 13 is connected to the ground terminal of the compressor. The main steps of monitoring the insulation performance of the compressor are as follows: Figure 4 or Figure 5 As shown:

[0038] A1: The compressor is powered on;

[0039] A2: The microcontroller calculates the insulation resistance value R+ of the positive electrode to the ground and the insulation resistance value R- of the negative electrode to the ground based on the data obtained in step A2;

[0040] A3: The single chip microcomputer presets the minimum resistance value Rmin and the fault resistance delimiter value Rnor, and the single chip microcomputer 30 compares the calculated positive electrode-to-ground insulation resistance value R+ and the negative electrode-to-ground insulation resistance value R- with the preset minimum resistance value Rmin and the fault resistance delimiter value Rnor; if either the positive electrode-to-ground insulation resistance value R+ or the negative electrode-to-ground insulation resistance value R- is less than the minimum resistance value Rmin, the C1 operation is performed; if both the positive electrode-to-ground insulation resistance value R+ and the negative electrode-to-ground insulation resistance value R- are greater than the minimum resistance value Rmin but either one is less than the fault resistance value Rnor, the C2 operation is performed; if both the positive electrode-to-ground insulation resistance value R+ and the negative electrode-to-ground insulation resistance value R- are greater than the fault resistance delimiter value Rnor, the single chip microcomputer re-enters A2 after timing T1; the length of T1 can be determined according to actual needs, such as 30 minutes, but is generally between 1 minute and 60 minutes.

[0041] C1: The MCU determines that it is a level 1 fault;

[0042] C2: The MCU determines it as a level 2 fault.

[0043] In other embodiments, such as Figure 6 As shown, in step A2, when the first electronic switch Q1 is opened or closed, a certain delay process is performed first, and then the single chip microcomputer 30 collects the voltage across the first pressure measuring resistor R5 and the second pressure measuring resistor R6; specifically, A2 includes the following steps:

[0044] A211: Close the first electronic switch and the third electronic switch;

[0045] A212: The voltage across the first and second pressure measuring resistors is collected for the first time after a delay of T2, where T2 is greater than 150 μs and less than 1 s.

[0046] A213: Close the second electronic switch and the third electronic switch;

[0047] A214: After a delay of T2, the voltages across the first and second pressure measuring resistors are collected for the second time. T2 is greater than 150 μs and less than 1 s.

[0048] A22: The single chip computer calculates the insulation resistance value of the positive pole to ground and the insulation resistance value of the negative pole to ground of the compressor based on the collected data and preset data.

[0049] When collecting data when the first electronic switch Q1 is turned on, the second electronic switch Q2 is turned off, and the third electronic switch Q3 is turned off. The microcontroller 30 controls the delay T2, and collects the voltage across the first and second pressure-measuring resistors R5 and R6. The delay T2 can be set based on actual needs, such as 200 μs, but is generally between 150 μs and 1 second. Setting the delay T2 ensures that the voltage collected by the MCU is more stable.

[0050] When collecting data when the first electronic switch Q1 is closed, the second electronic switch Q2 is open and the third electronic switch Q3 is closed. The microcontroller 30 controls a delay T3 during which the microcontroller 30 collects the voltage across the first and second pressure-measuring resistors R5 and R6. The delay T3 can be set based on actual needs, such as 200 μs, but is generally between 150 μs and 1 second. Setting the delay T3 ensures a more stable voltage collected by the MCU. Of course, the value of T3 can be consistent with the value of T2.

[0051] In another embodiment, Figure 6 As shown, steps P1-P3 are also included between A1 and A2:

[0052] P1: compressor pre-charge;

[0053] P2: MCU 30 reads the pre-charge completion flag signal:

[0054] P3: Determine whether the compressor has completed pre-charging. If so, proceed to step A2. Otherwise, jump back to P2 after an interval of time T4. The length of time T4 can be set as needed.

[0055] Pre-charging the compressor between A1 and A2 can prevent potential safety hazards such as sparks caused by excessive current during the compressor startup phase, and is also beneficial to increasing the life of the compressor.

Claims

1. A compressor insulation resistance monitoring circuit, comprising a basic part and a single chip microcomputer, characterized in that: The monitoring circuit further includes an isolation operational amplifier part, the base part and the single chip microcomputer are both connected to the isolation operational amplifier part, and the base part is not electrically connected to the single chip microcomputer. The basic part includes a first port that can be connected to the positive pole of the power supply, a second port that can be connected to the negative pole of the power supply, and a third port that can be grounded; the basic part includes a first module and a second module, the two ends of the first module are respectively connected to the first port and the second port, the two ends of the second module are respectively connected to the third port and the second port, the first module has a first pressure measuring resistor, the second module has a second pressure measuring resistor, the isolation operational amplifier part includes a first isolation operational amplifier and a second isolation operational amplifier, the two pins of the first isolation operational amplifier are connected to the two ends of the first pressure measuring resistor, and the two pins of the second isolation operational amplifier are connected At both ends of the second pressure measuring resistor, the first module includes a first pressure measuring branch and a first control branch, the first pressure measuring branch is connected in parallel with the control branch, the second module also includes a second control branch and a second pressure measuring branch, the second pressure measuring branch is connected in parallel with the second control branch, the first control branch includes a first electronic switch and a first current limiting resistor, the first electronic switch is connected in series with the first current limiting resistor, the second control branch includes a second electronic switch and a second current limiting resistor, the second electronic switch is connected in series with the second current limiting resistor, and the connection point between the first module and the second module is connected to the line of the second port including a third electronic switch.

2. The compressor insulation resistance monitoring circuit according to claim 1, characterized in that: The first pressure measuring branch includes the first pressure measuring resistor, and the second pressure measuring branch includes the second pressure measuring resistor.

3. The compressor insulation resistance monitoring circuit according to claim 2, characterized in that: The first pressure measuring branch includes a first voltage dividing resistor, which is connected in series with the first pressure measuring resistor. The second pressure measuring branch includes a second voltage dividing resistor, which is connected in series with the second pressure measuring resistor. The sum of the resistance values ​​of the first pressure measuring resistor and the first voltage dividing resistor is equal to the sum of the resistance values ​​of the second pressure measuring resistor and the second voltage dividing resistor. The resistance value of the first current limiting resistor, the resistance value of the second current limiting resistor, the resistance value of the first voltage dividing resistor and the resistance value of the second voltage dividing resistor are equal.

4. The compressor insulation resistance monitoring circuit according to claim 3, characterized in that: The line connecting the first module to the first port includes a first fuse, and the line connecting the second module to the third port includes a second fuse.

5. The compressor insulation resistance monitoring circuit according to claim 4, characterized in that: The electronic switch is a relay.

6. The compressor insulation resistance monitoring circuit according to claim 5, characterized in that: The relay is a reed relay.

7. A compressor control method, characterized in that: The compressor control method includes a monitoring method for monitoring the insulation resistance of the compressor using the compressor insulation resistance monitoring circuit according to any one of claims 1 to 6, the monitoring method including the following steps: A1: The compressor is powered on; A2: The single chip computer calculates the insulation resistance value of the positive electrode of the compressor to the ground and the insulation resistance value of the negative electrode to the ground; A3: The single-chip microcomputer compares the calculated positive electrode-to-ground insulation resistance value and the negative electrode-to-ground insulation resistance value with the minimum resistance value and the fault resistance threshold value preset by the single-chip microcomputer; if either the positive electrode-to-ground insulation resistance value or the negative electrode-to-ground insulation resistance value is less than the minimum resistance, the C1 operation is performed; if both the positive electrode-to-ground insulation resistance value and the negative electrode-to-ground insulation resistance value are greater than the minimum resistance value but either the positive electrode-to-ground insulation resistance value or the negative electrode-to-ground insulation resistance value is less than the fault resistance threshold value, the C2 operation is performed; if both the positive electrode-to-ground insulation resistance value and the negative electrode-to-ground insulation resistance value are greater than the fault resistance threshold value, the process re-enters A2; C1: The MCU determines that it is a level 1 fault; C2: The MCU determines it as a level 2 fault.

8. The compressor control method according to claim 7, characterized in that: The A2 comprises the following steps: A21: The single chip microcomputer collects the voltages across the first pressure measuring resistor and the second pressure measuring resistor when the first electronic switch and the second electronic switch are opened and closed respectively; A22: The single chip microcomputer calculates the insulation resistance value of the positive electrode to ground and the insulation resistance value of the negative electrode to ground of the compressor based on the data obtained in step A21.

9. The compressor control method according to claim 7, characterized in that: The A2 comprises the following steps: A211: Close the first electronic switch and the third electronic switch; A212: collecting the voltage across the first pressure measuring resistor and the second pressure measuring resistor for the first time after a delay of T2, where T2 is greater than 150 μs and less than 1 s; A213: Close the second electronic switch and the third electronic switch; A214: collecting the voltage across the first pressure measuring resistor and the second pressure measuring resistor for the second time after a delay of T2, where T2 is greater than 150 μs and less than 1 s; A22: The single chip microcomputer calculates the insulation resistance value of the positive pole to ground and the insulation resistance value of the negative pole to ground of the compressor based on the collected data and preset data.

10. The compressor control method according to claim 7, wherein: The following steps are also included before A3 returns to A2: A31: If both the positive electrode insulation resistance to ground and the negative electrode insulation resistance to ground are greater than the fault resistance threshold, the single chip computer re-enters A2 after a timer T1; T1 is greater than 1 minute and less than 60 minutes; The following steps are also included between A1 and A2: P1: pre-charge of the compressor; P2: The single chip microcomputer reads the pre-charge completion flag signal; P3: Determine whether the compressor has completed pre-charging. If so, proceed to step A2; otherwise, return to P2.

Images