A vehicle high-voltage loop contactor continuity detection circuit

Abstract

This invention relates to a continuity detection circuit for a high-voltage loop contactor in a vehicle. The detection circuit includes a sampling circuit and a detection branch. The first end of the detection branch is connected to the end of the contactor under test closest to the power battery, and the second end is connected to the end of the contactor under test furthest from the power battery. It also includes a first switch connected to the first end, a second switch connected to the second end, several voltage-dividing resistors, and a reference current source. The first switch, reference current source, first voltage-dividing resistor, third voltage-dividing resistor, and second switch are connected in series. The reference current source and the first voltage-dividing resistor are connected in series and then in parallel with the second voltage-dividing resistor. The sampling point of the sampling circuit is connected to the series connection point of the first and third voltage-dividing resistors. This detection circuit does not rely on the power battery for operation; instead, it uses a reference current source to provide a stable current for detecting the contactor's status, greatly improving the safety of the detection.

Description

Technical Field

[0001] This invention relates to a continuity detection circuit for a high-voltage loop contactor in a vehicle, belonging to the field of high-voltage technology. Background Technology

[0002] In high-voltage electrical system applications, high-voltage contactors are needed to control the on / off state of the high-voltage system and ensure the safety of the high-voltage loop. In high-voltage implementations, a high-voltage switch, called a high-voltage contactor, is installed in the electrical circuit on the high-voltage bus between the battery pack and other protected devices. When the high-voltage electrical system is not in use, the battery pack is automatically disconnected from other downstream protected devices. The high-voltage contactor uses an electromagnet to open and close conductive mechanical contacts connected to the high-voltage bus. The closing of the mechanical contacts forms a low-resistance circuit connection; the opening of the mechanical contacts controls the load (i.e., other protected devices) to disconnect from the circuit connection with the battery pack, thereby disconnecting the battery pack.

[0003] High-voltage contactors are crucial electrical control devices in electric vehicle battery systems. The safety status of the high-voltage contactor determines the safety of the entire high-voltage electrical system. Therefore, it is necessary to diagnose the on / off status of the high-voltage contactor during both vehicle stationary and running processes to ensure that the status of the high-voltage contactor matches the actual requirements.

[0004] Current high-voltage contactor condition diagnostic methods require a diagnostic circuit for each contactor to perform continuity testing. Furthermore, the diagnostic circuits for positive and negative contactors are separate and independent, leading to increased system circuit costs and complexity. For example, Chinese invention patent application CN 106427614A has the problem of numerous sampling points, reliance on the power battery for the measurement circuit, and potential current paths between the measurement circuit and external circuits, posing safety hazards. Additionally, because the reference ground of this measurement circuit depends on the vehicle ground, the system impedance of the measurement circuit may be introduced into the high and low voltage insulation impedance of the entire vehicle, affecting the vehicle's insulation performance and potentially causing vehicle safety issues. Summary of the Invention

[0005] The purpose of this invention is to provide a vehicle high-voltage loop contactor continuity detection circuit to solve the problems of poor safety and reliability in the prior art.

[0006] To achieve the above objectives, this invention proposes a vehicle high-voltage loop contactor continuity detection circuit. This circuit includes a sampling circuit and at least one detection branch. The first end of the detection branch is connected to the end of the contactor under test closest to the power battery, and the second end is connected to the end of the contactor under test furthest from the power battery. The detection branch includes a first switch connected to the first end, a second switch connected to the second end, several voltage-dividing resistors, and a reference current source. The first switch, reference current source, first voltage-dividing resistor, third voltage-dividing resistor, and second switch are connected in series. The reference current source and the first voltage-dividing resistor are connected in series and then in parallel with the second voltage-dividing resistor. The sampling point of the sampling circuit is connected to the series connection point of the first and third voltage-dividing resistors.

[0007] The beneficial effects are as follows: This invention compares the actual voltage at the sampling point in the sampling circuit with the calculated voltage at the sampling point in the sampling circuit to determine the on / off state of the contactor, thus achieving contactor diagnosis. The operation of this detection circuit does not rely on the power battery or vehicle ground; instead, it is equipped with a reference current source. This reference current source provides a stable current to detect the contactor's state, greatly improving the safety of the detection and reducing the impact of the circuit on the vehicle's insulation performance. Furthermore, detecting the actual voltage at the sampling point improves the reliability of the detection.

[0008] Furthermore, the high-voltage loop contactor continuity detection circuit of the vehicle includes two detection branches, a first detection branch and a second detection branch. The first detection branch and the second detection branch share a reference current source, a first voltage divider resistor, a second voltage divider resistor and a third voltage divider resistor.

[0009] The beneficial effects are: the first and second detection branches are used to detect the on / off status of the positive and negative contactors, respectively; the two detection branches share a common reference current source, the first voltage divider resistor, the second voltage divider resistor, and the third voltage divider resistor, further simplifying the circuit and saving costs.

[0010] Furthermore, both the first and second switches are relay switches.

[0011] The beneficial effect is that using a relay switch can more reliably control the opening and closing of the switch, making the test results more accurate and reliable.

[0012] Furthermore, the first voltage divider resistor and the second voltage divider resistor have the same resistance value.

[0013] The beneficial effect is that having the same resistance value for the first and second voltage divider resistors simplifies the calculation process and improves detection efficiency.

[0014] Furthermore, the sampling circuit includes an ADC circuit.

[0015] The beneficial effect is that the voltage at the sampling point can be collected more accurately through the ADC circuit, thus making the on / off detection of the contactor more reliable. Attached Figure Description

[0016] Figure 1 This is a circuit diagram of Embodiment 1 of the vehicle high-voltage loop contactor continuity detection circuit of the present invention;

[0017] Figure 2 This is a circuit diagram of Embodiment 2 of the vehicle high-voltage loop contactor continuity detection circuit of the present invention. Detailed Implementation

[0018] Example 1 of vehicle high-voltage loop contactor continuity detection circuit:

[0019] The vehicle high-voltage loop contactor continuity detection circuit (hereinafter referred to as the detection circuit) proposed in this embodiment only detects the positive contactor Relay P. The specific circuit is as follows: Figure 1 As shown, when testing the positive contactor Relay P (i.e., the positive control contactor of the high-voltage electrical loop, hereinafter referred to as the positive contactor), the testing circuit includes a sampling circuit and a testing branch. The first end of the testing branch is connected to the end of the positive contactor closest to the power battery (the end closest to the power battery is the positive output terminal of the power battery), and the second end of the testing branch is connected to the end of the positive contactor furthest from the power battery (the end furthest from the power battery is the end of the positive contactor connected to other protection devices).

[0020] The detection branch includes a first switch SW1 connected to the first end and a second switch SW3 connected to the second end; it also includes several voltage divider resistors and a reference current source I. ref Several voltage divider resistors include a first voltage divider resistor R1, a second voltage divider resistor R2, and a third voltage divider resistor R3; a first switch SW1, and a reference current source I. ref The first voltage divider resistor R1, the third voltage divider resistor R3, and the second switch SW3 are connected in series, with reference current source I. ref The first voltage divider resistor R1 is connected in series with the second voltage divider resistor R2; the sampling point V of the sampling circuit. adc Connect the series connection point of the first voltage divider resistor R1 and the third voltage divider resistor R3; the power battery (i.e., the battery pack) is V in the diagram. bat .

[0021] The principle of the detection circuit is that when the first switch SW1 and the second switch SW3 are closed, the voltage V at the sampling point is actually collected through the sampling circuit. adc Simultaneously, the voltage V at the sampling point is calculated, and the actual voltage V at the sampling point is then collected. adc The on / off state of the positive contactor can be detected by comparing it with the calculated voltage V at the sampling point.

[0022] In this embodiment, to more reliably control the closing and opening of each switch, each switch is a relay switch, and the relay switch is a normally open switch. Figure 1 The controller shown controls the closing of each relay switch. Of course, in other implementations, each switch can also be an electronic switch. Different application scenarios require different switching devices. This invention does not limit the specific implementation of the switch, as long as it can realize the opening and closing of the circuit.

[0023] To further simplify the calculation process, in this embodiment, the resistance values ​​of the first voltage divider resistor R1 and the second voltage divider resistor R2 are the same. In other embodiments, the resistance values ​​of the first voltage divider resistor R1 and the second voltage divider resistor R2 may also be different.

[0024] In order to acquire the voltage at the sampling point more accurately, in this embodiment, the sampling circuit is an ADC circuit, and the acquisition is completed by the ADC chip. Of course, the present invention does not limit the specific implementation of the sampling circuit, as long as the voltage at the sampling point can be acquired.

[0025] When this circuit performs positive contactor testing, the ground reference is the negative terminal of the battery pack (i.e., the power battery). This circuit does not limit the number of positive contactors during testing; there can be multiple positive contactors.

[0026] When the detection circuit does not detect the positive contactor, the driving path of the reference current source is a small loop consisting of the reference current source, the first voltage divider resistor R1, and the second voltage divider resistor R2.

[0027] When the detection circuit detects the positive contactor, there are two cases.

[0028] In case 1, if the positive contactor is disconnected, the driving path of the reference current source is a small loop consisting of the reference current source, the first voltage divider resistor R1, and the second voltage divider resistor R2.

[0029] In the second scenario, if the positive contactor is stuck, the driving path of the reference current source is divided into two paths: one is a small loop consisting of the reference current source, the first voltage divider resistor R1, and the second voltage divider resistor R2; the other is an external loop consisting of the reference current source, the first voltage divider resistor R1, and the third voltage divider resistor R3. Therefore, the on / off status of the positive contactor can be determined by the voltage at the sampling point.

[0030] The method for testing the continuity of a positive contactor is as follows:

[0031] 1) The controller closes the first switch SW1 and the second switch SW3, and the ADC circuit collects the voltage V at the sampling point. adc .

[0032] 2) The ADC circuit will collect the voltage V adc The data is sent to the controller, which calculates the theoretical voltage value of the sampling point under two conditions. In condition one, the theoretical voltage value of the sampling point is V1 = I * R2; in condition two, the theoretical voltage value of the sampling point is V2 = I * (R2 / / R3), where I is the stable current provided by the reference current source. The controller will then transfer the collected voltage V1 to the controller. adc Compare with V1 and V2 respectively. If (V1-V adc If V1 < 0.05, then the positive contactor is considered to be open;

[0033] If (V2-V adc If V2 < 0.05, then the positive contactor is considered to be stuck (i.e. connected). The 0.05 in the formula is a coefficient that can be adjusted according to the actual situation.

[0034] The same detection branch can also be used to detect the negative contactor, except that one end of the detection branch needs to be connected to the end of the negative contactor that connects to other protection devices, and the other end needs to be connected to the negative output terminal of the power battery.

[0035] Example 2 of vehicle high-voltage loop contactor continuity detection circuit:

[0036] The vehicle high-voltage loop contactor continuity detection circuit (hereinafter referred to as the detection circuit) proposed in this embodiment can detect not only the positive contactor Relay P (i.e., the positive control contactor of the high-voltage electrical loop, hereinafter referred to as the positive contactor) but also the negative contactor Relay N (the negative control contactor of the high-voltage electrical loop, hereinafter referred to as the negative contactor). The detection circuit can switch between detecting the positive and negative contactors via a switch. The specific detection circuit is as follows: Figure 2 As shown, it includes two detection branches, the first and the second. The first detection branch detects the positive contactor and is basically the same as the circuit structure in Embodiment 1. The difference is that the first detection branch also includes a fourth voltage divider resistor R4, which is connected in series between the third voltage divider resistor R3 and the second switch SW3.

[0037] The second detection branch is for detecting the negative contactor. The first end of the second detection branch is connected to the end of the negative contactor that is closer to the power battery (the end closer to the power battery is the negative output terminal of the power battery). The second end of the detection branch is connected to the end of the positive contactor that is farther away from the power battery (the end farther away from the power battery is the end of the negative contactor that is connected to other protection devices).

[0038] The second detection branch includes a third switch SW2 connected to the first end of the branch, a fourth switch SW4 connected to the second end of the branch, and a fifth voltage divider resistor R5; the first and second detection branches share a common reference current source I.ref The first voltage divider resistor R1, the second voltage divider resistor R2, and the third voltage divider resistor R3, the fourth switch SW4, the fifth voltage divider resistor R5, and the third voltage divider resistor R3 are connected in series.

[0039] The detection principle of the second detection branch is as follows: when the fourth switch SW4 and the third switch SW2 are closed, the voltage V at the sampling point is actually collected through the sampling circuit. adc Simultaneously, the voltage V at the sampling point is calculated, and the actual voltage V at the sampling point is then collected. adc The on / off state of the negative contactor can be detected by comparing it with the calculated voltage V at the sampling point.

[0040] In this embodiment, to more reliably control the closing and opening of each switch, each switch is a relay switch, and the relay switch is a normally open switch. Figure 2 The controller shown controls the closing of each relay switch. Of course, in other implementations, each switch can also be an electronic switch. Different application scenarios require different switching devices. This invention does not limit the specific implementation of the switch, as long as it can realize the opening and closing of the circuit.

[0041] To further simplify the calculation process, in this embodiment, the resistance values ​​of the first voltage divider resistor R1 and the second voltage divider resistor R2 are the same, and the resistance values ​​of the fourth voltage divider resistor R4 and the fifth voltage divider resistor R5 are the same. In other embodiments, the resistance values ​​of the first voltage divider resistor R1 and the second voltage divider resistor R2, as well as the resistance values ​​of the fourth voltage divider resistor R4 and the fifth voltage divider resistor R5, can also be different.

[0042] In order to acquire the voltage at the sampling point more accurately, in this embodiment, the sampling circuit is an ADC circuit, and the acquisition is completed by the ADC chip. Of course, the present invention does not limit the specific implementation of the sampling circuit, as long as the voltage at the sampling point can be acquired.

[0043] The following describes the testing methods for the continuity of positive and negative contactors.

[0044] When this circuit performs positive contactor testing, the ground reference is the negative terminal of the battery pack (i.e., the power battery); when performing negative contactor testing, the ground reference is the positive terminal of the battery pack. This circuit can only diagnose positive contactors or test negative contactors individually, and cannot perform them simultaneously. However, this invention does not limit the number of positive or negative contactors; there can be multiple positive or negative contactors.

[0045] The detection principle of the detection method is based on the following example, using a positive contactor:

[0046] When the detection circuit does not detect the positive contactor, the driving path of the reference current source is a small loop consisting of the reference current source, the first voltage divider resistor R1, and the second voltage divider resistor R2.

[0047] When the detection circuit detects the positive contactor, there are two scenarios.

[0048] In case 1, if the positive contactor is disconnected, the driving path of the reference current source is a small loop consisting of the reference current source, the first voltage divider resistor R1, and the second voltage divider resistor R2.

[0049] In scenario two, if the positive contactor is stuck, the driving path of the reference current source is divided into two: one is a small loop consisting of the reference current source, the first voltage divider resistor R1, and the second voltage divider resistor R2; the other is an external loop consisting of the reference current source, the first voltage divider resistor R1, the third voltage divider resistor R3, and the fourth voltage divider resistor R4. Therefore, the on / off status of the positive contactor can be determined by the voltage at the sampling point.

[0050] The detection principle of the negative contactor's on / off state differs from that of the positive contactor in that, when the detection circuit detects the negative contactor in case two, if the negative contactor is stuck, the driving path of the reference current source is divided into two: one is a small loop consisting of the reference current source, the first voltage divider resistor R1, and the second voltage divider resistor R2; the other is an external loop consisting of the reference current source, the first voltage divider resistor R1, the third voltage divider resistor R3, and the fifth voltage divider resistor R5.

[0051] The specific method for testing the continuity of the positive contactor is as follows:

[0052] 1) The controller closes the first switch SW1 and the second switch SW3, and opens the fourth switch SW4 and the third switch SW2. The ADC circuit then collects the voltage V at the sampling point. adc .

[0053] 2) The ADC circuit will collect the voltage V adc The data is sent to the controller, which calculates the theoretical voltage value of the sampling point under two conditions. In condition one, the theoretical voltage value of the sampling point is V1 = I * R2; in condition two, the theoretical voltage value of the sampling point is V2 = I * [R2 / / (R3+R4)], where I is the stable current provided by the reference current source. The controller will then transfer the collected voltage V1 to the controller. adc Compare with V1 and V2 respectively. If (V1-V adc If V1 < 0.05, then the positive contactor is considered to be open;

[0054] If (V2-V adc If V2 < 0.05, then the positive contactor is considered to be stuck. The 0.05 in the formula is a coefficient that can be adjusted according to the actual situation.

[0055] The specific method for testing the continuity of the negative contactor is as follows:

[0056] 1) The controller closes the fourth switch SW4 and the third switch SW2, and opens the first switch SW1 and the second switch SW3. The ADC circuit then collects the voltage V at the sampling point. adc .

[0057] 2) The ADC circuit will collect the voltage V adc The data is sent to the controller, which calculates the theoretical voltage value of the sampling point under two conditions. In condition one, the theoretical voltage value of the sampling point is V1 = I * R2; in condition two, the theoretical voltage value of the sampling point is V3 = I * [R2 / / (R3+R5)]. The controller then transmits the collected voltage V... adc Compare with V1 and V3 respectively. If (V1-V adc If V1 < 0.05, then the negative contactor is considered to be disconnected.

[0058] If (V3-V) adc If V3 < 0.05, then the negative contactor is considered to be stuck. The 0.05 in the formula is a coefficient that can be adjusted according to the actual situation.

[0059] The above method was verified through simulation.

[0060] When performing the simulation, the selected parameter is V. bat =200V; R1=R2=R3=1kΩ; R4=R5=10kΩ; I ref =10mA.

[0061] The on / off detection of the positive contactor was simulated according to the above method and process.

[0062] Actual simulation of closed positive contactor sampling to obtain V adc =209.17V - 200V = 9.17V;

[0063] Based on the calculation formula for the positive contactor above, we can conclude that:

[0064] V1 = 10V; V2 = 9.16667V

[0065] After assessment, (V2–V adc Since V2 = 0.0036 < 0.05, it can be determined that the positive contactor is stuck. In the actual simulation, the positive contactor is also stuck, which shows that the theoretical derivation is consistent with the actual application.

[0066] The on / off detection of the negative contactor was simulated according to the above method and process.

[0067] Actual simulation of closed negative contactor sampling to obtain V adc =9.16667V;

[0068] Based on the calculation formula for the negative contactor above, we can conclude that:

[0069] V1 = 10V; V3 = 9.16667V

[0070] After assessment, (V3–V adc Since V3 = 0 < 0.05, it can be determined that the negative contactor is stuck. In actual simulation, the negative contactor is also stuck, which shows that the theoretical derivation is consistent with actual application.

[0071] The operation of this detection circuit does not depend on the power battery and the vehicle ground. Instead, it is equipped with a reference current source. The reference current source provides a stable current to detect the status of the contactor, which greatly improves the safety of the detection and reduces the impact of the circuit on the insulation performance of the vehicle.

Claims

1. A vehicle high voltage loop contactor on-off detection circuit, characterized by, The vehicle high-voltage loop contactor on-off detection circuit comprises a controller, a sampling circuit and a detection branch, the detection branch comprising a first switch, a second switch, a third switch, a fourth switch, a reference current source, a first voltage dividing resistor, a second voltage dividing resistor, a third voltage dividing resistor, a fourth voltage dividing resistor and a fifth voltage dividing resistor, the first switch and the third switch being connected in series, one end of the first switch not connected to the third switch being connected to one end of the positive contactor close to the power battery, one end of the third switch not connected to the first switch being connected to one end of the negative contactor close to the power battery, the second switch, the fourth resistor and the fifth resistor being connected in series, one end of the second switch not connected to the fourth resistor being connected to one end of the positive contactor away from the power battery, one end of the fourth switch not connected to the fifth resistor being connected to one end of the negative contactor away from the power battery, the reference current source, the first voltage dividing resistor and the third voltage dividing resistor being connected in series, one end of the reference current source not connected to the first voltage dividing resistor being connected to the series connection point between the first switch and the third switch, one end of the third voltage dividing resistor not connected to the first voltage dividing resistor being connected to the series connection point between the fourth resistor and the fifth resistor, the second voltage dividing resistor being connected in parallel across the series branch comprising the reference current source and the first voltage dividing resistor; the sampling point of the sampling circuit being connected to the series connection point of the first voltage dividing resistor and the third voltage dividing resistor; the sampling circuit being configured to collect the voltage at the sampling point and send the actual collected voltage at the sampling point to the controller; the controller being configured to control the first switch and the second switch to be closed and the third switch and the fourth switch to be opened to realize the on-off detection of the positive contactor, and to control the third switch and the fourth switch to be closed and the first switch and the second switch to be opened to realize the on-off detection of the negative contactor; the controller being configured to obtain the actual collected voltage at the sampling point when detecting the on-off state of the current contactor to be detected, and to calculate the theoretical voltage V1 at the sampling point when the contactor to be detected is disconnected and the theoretical voltage V2 at the sampling point when the contactor to be detected is stuck, and to compare the actual collected voltage at the sampling point with the theoretical voltages V1 and V2 respectively, so as to detect the on-off state of the current contactor to be detected; V1 = I * R2, V2 = I * [R2 / / (R3 + R4)] when detecting the on-off state of the positive contactor, and V2 = I * [R2 / / (R3 + R5)] when detecting the on-off state of the negative contactor, wherein R4 and R5 are the resistance values of the fourth voltage dividing resistor and the fifth voltage dividing resistor respectively, R2 / / (R3 + R4) is the resistance value of the third voltage dividing resistor and the fourth voltage dividing resistor connected in series and then connected in parallel with the second voltage dividing resistor, and R2 / / (R3 + R5) is the resistance value of the third voltage dividing resistor and the fifth voltage dividing resistor connected in series and then connected in parallel with the second voltage dividing resistor.

2. The vehicle high pressure loop contactor on-off detection circuit according to claim 1, characterized by, The resistance values of the first voltage dividing resistor and the second voltage dividing resistor are the same.

3. The vehicle high pressure loop contactor on-off detection circuit of claim 1, wherein, The sampling circuit comprises an ADC circuit.

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