High-precision, low-power circuit supporting high-voltage interlock resistance detection and detection method thereof

Abstract

The present invention discloses a high-precision, low-power circuit supporting high-voltage interlock resistance detection and a detection method thereof, relating to the field of resistance detection technology, wherein the high-voltage interlock resistance detection circuit includes a high-voltage interlock voltage output circuit and a high-voltage interlock input recovery circuit; the high-voltage interlock voltage output circuit includes a power chip; a resistor R1 and a resistor R2 connected in series with the power chip; at least one pair of triodes and their supporting resistors R3 and R4 constituting a switching circuit; and a resistor R5 and a resistor R6 constituting a voltage divider circuit, the resistors R5 and R6 being connected in series, and their output ends being connected to an MCU sampling end. The circuit and method of the present invention can allow the circuit to enter low power consumption when high-voltage interlock detection is not required, thereby solving the problem of high loop power consumption; the circuit itself increases a protection mechanism for short-circuiting the circuit itself to short-circuit the power supply, and the circuit itself is more stable and reliable.

Description

Technical Field

[0001] The present invention relates to the technical field of resistance detection, in particular to a high-precision, low-power consumption circuit supporting high-voltage interlock resistance detection and a detection method thereof. Background Art

[0002] The various modules in the high-voltage circuit of new energy vehicles are connected through high-voltage connectors. Therefore, it is necessary to monitor the resistance of the entire circuit to diagnose whether the high-voltage connector is loose or detached, so as to avoid safety accidents caused by problems such as false connection or detachment.

[0003] The existing technology uses a battery management system to send a voltage signal to the high-voltage circuit. This signal is then divided by a resistor in the system and the equivalent resistance of the high-voltage circuit. The system then collects the divided voltage signal. However, the current high-voltage interlock detection circuit has poor accuracy, high power consumption throughout the loop, and no protection mechanism for the circuit itself against power shorts. Summary of the Invention

[0004] In view of the above existing problems, the present invention is proposed.

[0005] Therefore, the present invention provides a high-precision, low-power circuit that supports high-voltage interlock resistance detection and its detection method to solve the problems of poor accuracy of the current high-voltage interlock detection circuit, high power consumption of the entire loop, and no short-circuit protection mechanism for the circuit itself.

[0006] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0007] In the first aspect, the present invention provides a high-precision, low-power circuit that supports high-voltage interlock resistance detection, which includes a high-voltage interlock voltage output circuit and a high-voltage interlock input recovery circuit; the high-voltage interlock voltage output circuit includes a power supply chip; a resistor R1 and a resistor R2 connected in series with the power supply chip; at least one pair of transistors and their matching resistors R3 and R4 constituting a switching circuit; and a resistor R5 and a resistor R6 constituting a voltage divider circuit, the resistor R5 and the resistor R6 being connected in series, and their output ends being connected to the MCU sampling end; the high-voltage interlock input recovery circuit includes a voltage divider network including a resistor R12 and a resistor R13, which reduces the high-voltage signal to the MCU analog-to-digital conversion range; a low-resistance resistor R7, a voltage divider detection network formed together with the equivalent resistance of the resistor R2 and the high-voltage interlock loop; and a switch and protection circuit for implementing current limiting protection.

[0008] As a preferred solution of the high-precision, low-power circuit supporting high-voltage interlock resistance detection described in the present invention, the switch and protection circuit includes a switch circuit composed of a resistor R10 and a transistor Q3; and a protection circuit composed of a resistor R9, a resistor R11 and a transistor Q4.

[0009] In the second aspect, the present invention provides a high-voltage interlock resistance detection method, comprising the following steps: using a voltage tracking LDO to output a stable voltage, and supplying the stable voltage to a high-voltage interlock loop through a high-voltage interlock voltage output circuit; when high-voltage interlock detection is not required, the MCU enable signal is low, and the resistor R1 in the high-voltage interlock voltage output circuit remains in a series state, so that the entire circuit is in a low-power working state; when detection is required, the MCU enable signal is switched to a high level, driving the transistor Q1 in the switching circuit to close and short-circuit R1, so that the detection voltage is determined by the voltage divider network composed of resistor R2, the equivalent resistance of the high-voltage interlock loop and resistor R7; the detection voltage is reduced to the MCU analog-to-digital conversion sampling range through a voltage divider circuit composed of resistors R5 and R6, and the divided voltage is collected by the MCU analog-to-digital conversion module; based on the collected divided voltage value and a preset voltage divider ratio, the equivalent resistance of the high-voltage interlock loop is calculated using a voltage divider formula.

[0010] As a preferred embodiment of the high-voltage interlock resistance detection method described in the present invention, after calculating the equivalent resistance, the calculated equivalent resistance is compared with a preset normal resistance range to determine whether there is an abnormal state such as the high-voltage connector being loose, detached, or poorly connected.

[0011] As a preferred solution of the high-voltage interlock resistance detection method described in the present invention, in which: during the detection process, the status of the high-voltage interlock input recovery interface is monitored by the switch and the protection circuit. When the voltage across the resistor R11 exceeds the set threshold, the transistor Q4 is triggered to turn on, and the transistor Q3 is turned off, so that the detection current flows to the ground through the resistor R7 and the resistor R8, thereby realizing current limiting protection of the circuit.

[0012] As a preferred solution of the high-voltage interlock resistance detection method described in the present invention, the MCU comprehensively collects the divided voltage and protection circuit status, and outputs the high-voltage interlock circuit status information, which is used to judge the contact status of the high-voltage connector and the health status of the circuit in real time.

[0013] As a preferred solution of the high-voltage interlock resistance detection method of the present invention, the voltage division formula is expressed as follows:

[0014] V_out=V_in×(R7 / (R2+R7+R_load))

[0015] Where V_out is the divided voltage collected by the MCU, Rload is the equivalent resistance of the high-voltage interlock circuit, R2 and R7 are the resistances of resistors R2 and R7 respectively, and V_in is the stable voltage output by the LDO.

[0016] The beneficial effects of the present invention are as follows: the high-voltage interlock circuit adopts a voltage tracking LDO power supply and high-precision data acquisition, which can more accurately calculate the equivalent resistance R of the high-voltage interlock circuit;

[0017] When high-voltage interlock detection is not required, the circuit can enter low power consumption, solving the problem of high loop power consumption;

[0018] The circuit itself adds a protection mechanism for short circuit and short power supply, making the circuit itself more stable and reliable. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0020] Figure 1 This is a circuit diagram of a high-precision, low-power circuit supporting high-voltage interlock resistance detection in Example 1. DETAILED DESCRIPTION

[0021] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0022] In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention may also be implemented in other ways different from those described herein. Those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0023] Secondly, the term "one embodiment" or "embodiment" herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in various places throughout this specification does not necessarily refer to the same embodiment, nor does it refer to a separate or selective embodiment that is mutually exclusive of other embodiments.

[0024] Example 1, reference Figure 1 , which is the first embodiment of the present invention, provides a high-precision, low-power circuit that supports high-voltage interlock resistance detection, including a high-voltage interlock voltage output circuit and a high-voltage interlock input recovery circuit. The output circuit is used to provide a stable voltage to the high-voltage interlock loop and realize different working modes through voltage division and switch switching; the input recovery circuit is used to reduce the detection signal of the high-voltage interlock loop to the MCU ADC sampling range, and at the same time provide a protection circuit to perform current limiting protection for abnormal conditions (such as short ground or short power).

[0025] The high-voltage interlock voltage output circuit includes:

[0026] Power chip;

[0027] Resistors R1 and R2 connected in series with the power chip;

[0028] At least one pair of transistors and their matching resistors R3 and R4 constituting a switching circuit;

[0029] and resistors R5 and R6 forming a voltage divider circuit, wherein the resistors R5 and R6 are connected in series, and the output ends thereof are connected to the MCU sampling end;

[0030] The high voltage interlock input recovery circuit includes:

[0031] The voltage divider network including resistors R12 and R13 reduces the high voltage signal to the analog-to-digital conversion range of the MCU;

[0032] A low-resistance resistor R7, together with the resistor R2 and the equivalent resistance of the high-voltage interlock circuit, forms a voltage-dividing detection network;

[0033] And a switch and a protection circuit for achieving current limiting protection.

[0034] Specifically, the power chip uses a model LMX-5.0 voltage-tracking low-dropout regulator (LDO). Its input is connected to a 12V DC power supply through a filter circuit, and its output provides a fixed 5V stable voltage with a deviation of less than 10 mV from a high-precision reference voltage. The output of the LDO is directly connected to the power supply node of the output circuit.

[0035] The first resistor R1 is 100kΩ, and the second resistor R2 is 1kΩ. The connection method is: one end of R1 is directly connected to the LDO output voltage, the downstream end of R1 is connected to the upstream end of R2, and the downstream end of R2 is connected to the high-voltage interlock loop load end or detection node.

[0036] To achieve the transition between low-power and high-precision detection modes, a switch circuit is connected in parallel across R1. This circuit utilizes NPN transistor Q1, supplemented by Q2 for improved reliability. Their collectors are connected across the upstream and downstream ends of R1, respectively. Q1's base is connected to the MCU enable signal, MCU_EN, via a current-limiting resistor (e.g., 10 kΩ). When MCU_EN is high, Q1 conducts, shorting R1. When MCU_EN is low, Q1 turns off, maintaining the series connection between R1 and the input, thus achieving a low-power standby mode.

[0037] To collect the output voltage, a voltage divider network is provided. The voltage divider circuit consists of resistors R5 and R6, where one end of R5 is connected to the common node of R1 and R2 (or after Q1 is short-circuited), and the other end is grounded through R6; the middle node of the voltage divider circuit is connected to the analog-to-digital converter (ADC) sampling terminal of the MCU via a wire for subsequent calculation of the equivalent resistance value of the high-voltage interlock loop.

[0038] The input sampling circuit uses a voltage divider network consisting of resistors R12 and R13 (each 100 kΩ) connected in series. Its upstream end is connected to the detection node of the high-voltage interlock circuit (for example, the downstream end of R2), and its downstream end is grounded. This voltage divider network reduces the high voltage level to the MCU ADC input range, while the intermediate node is also used by another MCU sampling channel.

[0039] To accurately reflect the resistance of the high-voltage interlocking loop, a low-resistance voltage divider element R7 (100 Ω) is connected in parallel to the downstream end of R2, and its other end is connected to the above-mentioned voltage divider network, so that the collected voltage has a linear relationship with the equivalent resistance of the high-voltage interlocking loop.

[0040] The switch and protection circuit consists of a switch circuit consisting of resistor R10 (select 10 kΩ) and NPN transistor Q3. One end of the switch is connected to the parallel node of R7 and R2, and the other end is grounded. Normally, Q3 is kept on to provide a stable ground reference for R7.

[0041] The protection divider network consists of resistors R9 (20 kΩ) and R11 (20 kΩ) connected in series. Its upstream end is connected to the high-voltage side of the high-voltage interlock circuit (e.g., the LDO output or upstream of R1), and its downstream end is grounded. The intermediate node of the protection divider network is connected via a wire to the base of NPN transistor Q4. Q4's collector is connected to the base of Q3, and its emitter is grounded. If the high-voltage interlock input is shorted to the power supply for some reason, the voltage across R11 in the divider network rises to approximately 0.7V or above, triggering Q4 to turn on, thereby turning off Q3 and forcing the sense current to flow to ground through current-limiting resistor R8 (50 Ω), thus implementing overcurrent protection.

[0042] The MCU uses the ADC sampling terminal to collect the sampled voltages from the output circuit voltage divider (R5, R6) and the input sampling circuit (R12, R13). Simultaneously, the MCU controls MCU_EN via a digital signal to switch between low-power and detection modes. The collected divided voltages are calculated using a preset voltage divider ratio and a formula to determine the equivalent resistance of the high-voltage interlock circuit, thereby determining whether the high-voltage connector is loose, disconnected, or poorly connected.

[0043] The working principle of the high-precision, low-power circuit supporting high-voltage interlock resistance detection described in the present invention is as follows:

[0044] (1) Standby state - When the system does not perform high-voltage interlock detection, MCU_EN is at a low level. At this time, Q1 is cut off, R1 and R2 are in series, and the voltage drop in the output circuit is shared by R1 and R2. The system is in a low-power state, and the MCU regularly samples the divided voltage to maintain monitoring.

[0045] (2) Detection status - When detection is required, the MCU sets the MCU_EN signal to a high level, driving Q1 to conduct and short-circuiting R1. At this time, the detection voltage is mainly determined by the voltage divider network composed of R2, the equivalent resistance of the high-voltage interlock circuit, and R7. The voltage divider voltage reflects the contact status of the connector in the high-voltage interlock circuit. After the MCU collects this voltage, it combines the preset voltage divider ratio and uses the voltage divider formula to calculate the actual resistance value. When the calculated result deviates from the preset normal resistance range, it can be determined that the connector is in an abnormal state such as loose, detached, or poorly connected.

[0046] (3) Protection Mechanism - During the detection process, if the high-voltage interlock input is shorted to the power supply due to a connector anomaly, the voltage across R11 in the protection voltage divider network will rise to more than approximately 0.7V. At this time, Q4 will turn on, causing Q3 to turn off. This will force the detection current to flow to ground through the current-limiting resistor R8, thereby limiting the damage to circuit components caused by excessive current. The protection status is detected by the MCU, which then triggers an alarm or protective measures.

[0047] In summary, this embodiment, through the combined design of a voltage-tracking LDO, series / short-circuit switching, a precision voltage divider network, and protection circuitry, achieves high-precision detection and real-time monitoring of the high-voltage interlock resistance, while also providing low-power standby and overcurrent protection. The clear connections between various components and the rational structure effectively prevent safety incidents caused by loose, disconnected, or poorly connected high-voltage interlock connectors, and provide reliable current-limiting protection in the event of ground or power shorts.

[0048] Example 2: This embodiment provides a high-voltage interlock resistance detection method, which is based on the high-precision, low-power circuit supporting high-voltage interlock resistance detection in Example 1, and specifically includes the following steps:

[0049] A voltage tracking LDO is used to output a stable voltage, and the stable voltage is supplied to the high-voltage interlock circuit through a high-voltage interlock voltage output circuit;

[0050] When high-voltage interlock detection is not required, the MCU enable signal is at a low level, and the resistor R1 in the high-voltage interlock voltage output circuit remains in a series state, so that the entire circuit is in a low-power working state;

[0051] When detection is required, the MCU enable signal is switched to a high level, driving the transistor Q1 in the switch circuit to close and short-circuit R1, so that the detection voltage is determined by the voltage divider network composed of resistor R2, the equivalent resistance of the high-voltage interlock circuit and resistor R7;

[0052] The detection voltage is reduced to the MCU analog-to-digital conversion sampling range through a voltage divider circuit composed of resistors R5 and R6, and the divided voltage is collected by the MCU analog-to-digital conversion module;

[0053] Based on the collected divided voltage value and the preset divided voltage ratio, the equivalent resistance of the high-voltage interlocking circuit is calculated using the voltage divided formula.

[0054] Furthermore, after the equivalent resistance is calculated, the calculated equivalent resistance is compared with a preset normal resistance range to determine whether there is an abnormal state such as the high-voltage connector being loose, falling off, or having a poor connection.

[0055] During the detection process, the status of the high-voltage interlock input recovery interface is monitored through the switch and protection circuit. When the voltage across the resistor R11 exceeds the set threshold, the transistor Q4 is triggered to turn on, and the transistor Q3 is turned off, so that the detection current flows to the ground through the resistor R7 and the resistor R8, realizing current limiting protection for the circuit.

[0056] The MCU comprehensively collects the divided voltage and the protection circuit status, and outputs the high-voltage interlock circuit status information, which is used to judge the contact status of the high-voltage connector and the health of the circuit in real time. Preferably, the voltage division formula is expressed as:

[0057] V_out=V_in×(R7 / (R2+R7+R_load))

[0058] Where V_out is the divided voltage collected by the MCU, Rload is the equivalent resistance of the high-voltage interlock circuit, R2 and R7 are the resistances of resistors R2 and R7 respectively, and V_in is the stable voltage output by the LDO.

[0059] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A high-precision, low-power circuit supporting high-voltage interlock resistance detection, characterized by: It includes a high-voltage interlock voltage output circuit and a high-voltage interlock input recovery circuit; The high-voltage interlock voltage output circuit includes: Power chip; Resistors R1 and R2 connected in series with the power chip; At least one pair of transistors and their matching resistors R3 and R4 constituting a switching circuit; and resistors R5 and R6 forming a voltage divider circuit, wherein the resistors R5 and R6 are connected in series, and the output ends thereof are connected to the MCU sampling end; The high voltage interlock input recovery circuit includes: The voltage divider network including resistors R12 and R13 reduces the high voltage signal to the analog-to-digital conversion range of the MCU; A low-resistance resistor R7, together with the resistor R2 and the equivalent resistance of the high-voltage interlock circuit, forms a voltage-dividing detection network; and a switch and a protection circuit for implementing current limiting protection; The switch and protection circuit include: A switching circuit consisting of resistor R10 and transistor Q3; A protection circuit consisting of resistor R9, resistor R11 and transistor Q4; During the detection process, the status of the high-voltage interlock input recovery interface is monitored through the switch and protection circuit. When the voltage across the resistor R11 exceeds the set threshold, the transistor Q4 is triggered to turn on, and the transistor Q3 is turned off, so that the detection current flows to the ground through the resistor R7 and the resistor R8, realizing current limiting protection for the circuit.

2. The high-precision, low-power circuit supporting high-voltage interlock resistance detection according to claim 1, characterized in that: The power supply chip adopts a voltage tracking LDO power supply.

3. A high-voltage interlock resistance detection method based on the high-precision, low-power circuit supporting high-voltage interlock resistance detection according to any one of claims 1 to 2, characterized in that: The following steps are included: A voltage tracking LDO is used to output a stable voltage, and the stable voltage is supplied to the high-voltage interlock circuit through a high-voltage interlock voltage output circuit; When high-voltage interlock detection is not required, the MCU enable signal is at a low level, and the resistor R1 in the high-voltage interlock voltage output circuit remains in a series state, so that the entire circuit is in a low-power working state; When detection is required, the MCU enable signal is switched to a high level, driving the transistor Q1 in the switch circuit to close and short-circuit R1, so that the detection voltage is determined by the voltage divider network composed of resistor R2, the equivalent resistance of the high-voltage interlock circuit and resistor R7; The detection voltage is reduced to the MCU analog-to-digital conversion sampling range through a voltage divider circuit composed of resistors R5 and R6, and the divided voltage is collected by the MCU analog-to-digital conversion module; Based on the collected divided voltage value and the preset divided voltage ratio, the equivalent resistance of the high-voltage interlocking circuit is calculated using the voltage divided formula.

4. The high-voltage interlock resistance detection method according to claim 3, wherein: After calculating the equivalent resistance, the calculated equivalent resistance is compared with the preset normal resistance range to determine whether there is any abnormal condition such as the high-voltage connector being loose, falling off, or having a poor connection.

5. The high-voltage interlock resistance detection method according to claim 4, wherein: During the detection process, the status of the high-voltage interlock input recovery interface is monitored through the switch and protection circuit. When the voltage across the resistor R11 exceeds the set threshold, the transistor Q4 is triggered to turn on, and the transistor Q3 is turned off, so that the detection current flows to the ground through the resistor R7 and the resistor R8, realizing current limiting protection for the circuit.

6. The high-voltage interlock resistance detection method according to claim 5, wherein: The MCU comprehensively collects the divided voltage and protection circuit status and outputs the high-voltage interlock circuit status information, which is used to judge the contact status of the high-voltage connector and the health of the circuit in real time.

7. The high-voltage interlock resistance detection method according to claim 3, wherein: The voltage divider formula is expressed as, V_out=V_in×(R7 / (R2+R7+R_load)) Where V_out is the divided voltage collected by the MCU, Rload is the equivalent resistance of the high-voltage interlock circuit, R2 and R7 are the resistances of resistors R2 and R7 respectively, and V_in is the stable voltage output by the LDO.

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