High-precision low-power-consumption circuit supporting high-voltage interlocking resistance detection and detection method thereof

Abstract

The invention discloses a high-precision low-power-consumption circuit supporting high-voltage interlocking resistance detection and a detection method thereof, and relates to the technical field of resistance detection, and the high-voltage interlocking resistance detection circuit comprises a high-voltage interlocking voltage output circuit and a high-voltage interlocking input recovery circuit; the high-voltage interlocking voltage output circuit comprises a power supply chip; the resistor R1 and the resistor R2 are connected with the power supply chip in series; the at least one pair of triodes, the resistor R3 and the resistor R4 are matched with the triodes; the resistor R5 and the resistor R6 form a voltage division circuit, the resistor R5 and the resistor R6 are connected in series, and the output ends of the resistor R5 and the resistor R6 are connected with the sampling end of the MCU. According to the circuit and the method, when high-voltage interlocking detection is not needed, the circuit can enter low power consumption, and the problem of high loop power consumption is solved; and a protection mechanism of short ground and short power supply of the circuit is added, so that the circuit 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 and low-power circuit for supporting high-voltage interlock resistance detection and its detection method. Background Art

[0002] Each module in the high-voltage circuit of a new energy vehicle is connected through a high-voltage connector. Therefore, it is necessary to monitor the resistance value of the entire circuit to diagnose whether the high-voltage connector is loose or detached, and avoid safety accidents caused by problems such as poor connection or detachment.

[0003] The prior art is to send a voltage signal from the battery management system to the high-voltage circuit, and then divide the voltage through the resistor on the system and the equivalent resistance of the high-voltage circuit, and the system collects the voltage signal after voltage division. However, the current high-voltage interlock detection circuit has poor accuracy, high power consumption of the entire loop, and there is no protection mechanism for short circuit to ground and short circuit to power supply for the circuit itself. 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 and low-power circuit for supporting 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 protection mechanism for short circuit to ground and short circuit to power supply for the circuit itself.

[0006] To solve the above technical problems, the present invention provides the following technical solutions: In a first aspect, the present invention provides a high-precision and low-power circuit for supporting high-voltage interlock resistance detection, which includes a high-voltage interlock voltage output circuit and a high-voltage interlock input feedback circuit; the high-voltage interlock voltage output circuit includes a power supply chip; resistors R1 and R2 connected in series with the power supply chip; at least one pair of triodes forming a switching circuit and their supporting resistors R3 and R4; and resistors R5 and R6 forming a voltage division circuit, the resistors R5 and R6 are connected in series, and their output ends are connected to the MCU sampling end; the high-voltage interlock input feedback circuit includes a voltage division network including resistors R12 and R13 to reduce the high-voltage signal to the MCU analog-to-digital conversion range; a low-resistance resistor R7, a voltage division detection network formed by the resistor R2 and the equivalent resistance of the high-voltage interlock circuit; and a switch and protection circuit for realizing current limiting protection.

[0007] As a preferred solution of the high-precision and low-power circuit for supporting high-voltage interlock resistance detection of the present invention, wherein: the switch and protection circuit includes a switching circuit composed of a resistor R10 and a triode Q3; a protection circuit composed of a resistor R9, a resistor R11 and a triode Q4.

[0008] Second aspect, the present invention provides a method for detecting the resistance value of a high-voltage interlock, including the following steps: using a voltage-tracking LDO to output a stable voltage, and supplying the stable voltage to the 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 at a low level, and the resistor R1 in the high-voltage interlock voltage output circuit remains in a series state, making the entire circuit operate in a low-power state; when detection is needed, switch the MCU enable signal to a high level to drive the triode Q1 in the switch circuit to close and short-circuit R1, so that the detection voltage is determined by the voltage division network composed of resistor R2, the equivalent resistance value of the high-voltage interlock loop, and resistor R7; reduce the detection voltage to the sampling range of the MCU analog-to-digital conversion through the voltage division circuit composed of resistor R5 and resistor R6, and collect the divided voltage by the MCU analog-to-digital conversion module; based on the collected divided voltage value and the preset voltage division ratio, calculate the equivalent resistance value of the high-voltage interlock loop using the voltage division formula.

[0009] As a preferred solution of the method for detecting the resistance value of a high-voltage interlock according to the present invention, wherein: after calculating the equivalent resistance value, compare the calculated equivalent resistance value with the preset normal resistance range to determine whether there are abnormal states such as loose, detached, or poor contact of the high-voltage connector.

[0010] As a preferred solution of the method for detecting the resistance value of a high-voltage interlock according to the present invention, wherein: during the detection process, monitor the state of the high-voltage interlock input feedback interface through a switch and protection circuit. When the voltage across resistor R11 exceeds the set threshold, trigger the triode Q4 to conduct, causing the triode Q3 to turn off, so that the detection current flows to the ground through resistor R7 and resistor R8, realizing current limiting protection for the circuit.

[0011] As a preferred solution of the method for detecting the resistance value of a high-voltage interlock according to the present invention, wherein: the MCU comprehensively collects the divided voltage and the state of the protection circuit, and outputs the state information of the high-voltage interlock loop for real-time judgment of the contact state of the high-voltage connector and the health status of the loop.

[0012] As a preferred solution of the method for detecting the resistance value of a high-voltage interlock according to the present invention, wherein: the voltage division formula is expressed as V_out = V_in × (R7 / (R2 + R7 + R_load)) In the formula, V_out is the divided voltage collected by the MCU, Rload is the equivalent resistance value of the high-voltage interlock loop, R2 and R7 are the resistance values of resistor R2 and resistor R7 respectively, and V_in is the stable voltage output by the LDO.

[0013] 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 calculate the equivalent resistance value R of the high-voltage interlock loop more accurately; When high-voltage interlock detection is not required, the circuit can enter a low-power state, solving the problem of high loop power consumption; The circuit itself adds a protection mechanism for short circuit to ground and short circuit to power supply, making the circuit itself more stable and reliable. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0015] Figure 1 It is the circuit diagram of the high-precision and low-power circuit supporting high-voltage interlock resistance detection in Embodiment 1. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0016] In order to make the above objects, features, and advantages of the present invention more obvious and understandable, the following will describe the specific embodiments of the present invention in detail with reference to the accompanying drawings of the specification.

[0017] In the following description, many specific details are set forth in order to fully understand the present invention. However, the present invention can also be implemented in other ways different from those described herein. Those skilled in the art can make similar extensions without departing from the connotation of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed below.

[0018] Secondly, the so-called "one embodiment" or "embodiment" herein refers to a specific feature, structure, or characteristic that can be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment that is mutually exclusive with other embodiments.

[0019] Embodiment 1, referring to Figure 1 , which is the first embodiment of the present invention. This embodiment provides a high-precision and low-power circuit supporting high-voltage interlock resistance detection, including a high-voltage interlock voltage output circuit and a high-voltage interlock input feedback circuit. The output circuit is used to provide a stable voltage to the high-voltage interlock loop and achieve different working modes through voltage division and switch switching; the input feedback 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 limit the current in case of abnormal conditions (such as short circuit to ground or short circuit to power supply).

[0020] 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 a pair of triodes that make up the switching circuit and their supporting resistors R3 and R4; And resistors R5 and R6 that make up the voltage dividing circuit, where the resistors R5 and R6 are connected in series, and their output terminals are connected to the MCU sampling terminal; The high-voltage interlock input feedback circuit includes, A voltage dividing network including resistors R12 and R13 that reduces the high-voltage signal to the MCU analog-to-digital conversion range; A low-value resistor R7, a voltage dividing detection network jointly formed with the resistor R2 and the equivalent resistance value of the high-voltage interlock loop; And a switch and protection circuit for implementing current limiting protection.

[0021] Specifically, the power supply chip uses a voltage tracking type low-dropout regulator (LDO) with the model number LMX-5.0. Its input terminal is connected to a 12V DC power supply through a filtering circuit, and the output terminal fixedly outputs a stable 5V voltage, and the deviation between the output and the high-precision reference voltage is less than 10 mV. The output terminal of the LDO is directly connected to the power supply node of the output circuit.

[0022] The first resistor R1 is selected as 100 kΩ, and the second resistor R2 is selected as 1 kΩ. Their 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 the detection node.

[0023] To achieve the conversion between the low-power consumption and high-precision detection modes, a switching circuit is connected in parallel across both ends of R1. Among them, the switching circuit uses an NPN transistor Q1, and Q2 is used as an auxiliary to improve reliability. Its collector is respectively connected across the upstream end and the downstream end of R1; the base of Q1 is connected to the MCU enable signal MCU_EN through a current limiting resistor (such as 10 kΩ). When MCU_EN is at a high level, Q1 conducts and shorts R1; when MCU_EN is at a low level, Q1 cuts off and R1 remains in a series state, thereby achieving the standby low-power consumption mode.

[0024] To collect the output voltage, a voltage dividing network is provided. The voltage dividing circuit is composed of resistors R5 and R6. One end of R5 is connected to the common node of R1 and R2 (or after Q1 is shorted), and the other end is grounded through R6; the middle node of the voltage dividing circuit is connected to the analog-to-digital conversion (ADC) sampling terminal of the MCU through a wire for subsequent calculation of the equivalent resistance value of the high-voltage interlock loop.

[0025] In the input feedback circuit, a voltage dividing network composed of resistors R12 and R13 (each selected as 100 kΩ) in series is adopted. Its upstream end is connected to the detection node of the high-voltage interlock loop (for example, connected to the downstream end of R2), and the downstream end is grounded. This voltage dividing network reduces the high-voltage level to the input range of the MCU ADC, and its middle node is also used by another sampling channel of the MCU.

[0026] To accurately reflect the resistance value of the high-voltage interlock loop, a low-resistance voltage dividing component R7 (selected as 100 Ω) is connected in parallel at the downstream end of R2, and the other end is connected to the above voltage dividing network, so that the collected voltage has a linear relationship with the equivalent resistance value of the high-voltage interlock loop.

[0027] The switch and protection circuit consists of a switch circuit composed of a resistor R10 (selected as 10 kΩ) and an NPN transistor Q3. One end is connected to the parallel node of R7 and R2, and the other end is grounded. Usually, Q3 is kept conducting to provide a stable ground reference for R7. The protection voltage dividing network is composed of resistors R9 (selected as 20 kΩ) and R11 (selected as 20 kΩ) in series. Its upstream end is connected to the high-voltage side of the high-voltage interlock loop (such as the LDO output or the upstream of R1), and the downstream end is grounded; the middle node of the protection voltage dividing network is connected to the base of the NPN transistor Q4 through a wire, the collector of Q4 is connected to the base of Q3, and the emitter is grounded. When the high-voltage interlock input interface is short-circuited to the power supply due to some reason, the voltage across R11 in the voltage dividing network rises to more than about 0.7V, triggering Q4 to conduct, so that Q3 is cut off, forcing the detection current to flow to the ground through the current-limiting resistor R8 (selected as 50 Ω), realizing the current-limiting protection for overcurrent.

[0028] The MCU respectively samples the sampling voltages of the output circuit voltage dividing circuit (R5, R6) and the input feedback circuit (R12, R13) through the ADC sampling terminal; at the same time, the MCU controls MCU_EN through a digital signal to realize the switching between the low-power consumption and detection modes. The collected voltage dividing voltage is calculated through a preset voltage dividing ratio and formula to obtain the equivalent resistance value of the high-voltage interlock loop, and then to judge whether there are faults such as looseness, detachment or virtual connection of the high-voltage connector.

[0029] The working principle of the high-precision and low-power consumption circuit supporting high-voltage interlock resistance detection described in the present invention is as follows: (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, and R1 and R2 are in series. The voltage drop in the output circuit is shared by R1 and R2 together, and the system is in a low-power consumption state. The MCU periodically samples the voltage dividing voltage to maintain monitoring.

[0030] (2) Detection status - When detection is required, the MCU sets the MCU_EN signal to high level, driving Q1 to conduct and shorting R1. At this time, the detection voltage is mainly determined by the voltage division network composed of R2, the equivalent resistance value of the high-voltage interlock loop, and R7, and the divided voltage reflects the contact status of the connectors in the high-voltage interlock loop. After the MCU samples this voltage, combined with the preset voltage division ratio, the actual resistance value is calculated using the voltage division formula. When the calculation result deviates from the preset normal resistance range, it can be determined that there are abnormal conditions such as loosening, detachment, or poor contact of the connectors.

[0031] (3) Protection mechanism - During the detection process, if the high-voltage interlock input terminal is short-circuited to the power supply due to abnormal connectors, the voltage across R11 in the protection voltage division network will rise above about 0.7V. At this time, Q4 conducts, causing Q3 to turn off. This forces the detection current to flow to the ground through the current-limiting resistor R8, thereby limiting the damage to circuit components caused by excessive current, and the protection status is detected by the MCU, and then an alarm or protection measure is triggered.

[0032] In summary, through the combined design of a voltage-tracking LDO, series / short-circuit switching, a precision voltage division network, and a protection circuit in this embodiment, high-precision detection and real-time monitoring of the high-voltage interlock resistance value are achieved, and at the same time, it has the functions of low-power standby and over-current protection. The connections between all parts are clear and the structure is reasonable, which can effectively prevent safety accidents caused by loosening, detachment, or poor contact of high-voltage interlock connectors, and provide reliable current-limiting protection in case of short-to-ground or short-power-supply faults.

[0033] Embodiment 2 provides a method for detecting the high-voltage interlock resistance value, which is based on the high-precision and low-power circuit supporting high-voltage interlock resistance value detection in Embodiment 1, and specifically includes the following steps. Use a voltage-tracking LDO to output a stable voltage, and supply this stable voltage to the 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 at low level, and the resistor R1 in the high-voltage interlock voltage output circuit remains in series, making the entire circuit in a low-power working state. When detection is required, switch the MCU enable signal to high level, driving the triode Q1 in the switch circuit to close and short R1, so that the detection voltage is determined by the voltage division network composed of the resistor R2, the equivalent resistance value of the high-voltage interlock loop, and the resistor R7. Reduce the detection voltage to the MCU analog-to-digital conversion sampling range through a voltage division circuit composed of the resistor R5 and the resistor R6, and collect this divided voltage by the MCU analog-to-digital conversion module. Based on the collected divided voltage value and the preset voltage division ratio, calculate the equivalent resistance value of the high-voltage interlock loop using the voltage division formula.

[0034] Further, after calculating the equivalent resistance value, compare the calculated equivalent resistance value with the preset normal resistance range to determine whether there are abnormal states such as loosening, falling off, or poor contact of the high-voltage connector.

[0035] During the detection process, monitor the status of the high-voltage interlock input feedback interface through the switch and protection circuit. When the voltage across the two ends of the resistor R11 exceeds the set threshold, trigger the conduction of the triode Q4 and turn off the triode Q3, so that the detection current flows to the ground through the resistor R7 and the resistor R8, realizing the current limiting protection of the circuit.

[0036] The MCU comprehensively collects the divided voltage and the status of the protection circuit, and outputs the status information of the high-voltage interlock loop for real-time judgment of the contact status of the high-voltage connector and the health status of the loop. Preferably, the voltage division formula is expressed as V_out = V_in×(R7 / (R2 + R7 + R_load)) In the formula, V_out is the divided voltage collected by the MCU, Rload is the equivalent resistance value of the high-voltage interlock loop, R2 and R7 are the resistance values of the resistors R2 and R7 respectively, and V_in is the stable voltage output by the LDO.

[0037] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the spirit and scope of the technical solutions of the present invention, and they should all be covered by the scope of the claims of the present invention.

Claims

1. A high-precision, low-power circuit supporting high-voltage interlock resistance detection, characterized in that: It includes a high-voltage interlock voltage output circuit and a high-voltage interlock input recovery circuit; The high-voltage interlock voltage output circuit comprises: Power chip; Resistors R1 and R2 connected in series with the power chip; At least one pair of transistors constituting a switch circuit and their matching resistors R3 and R4; and a resistor R5 and a resistor R6 constituting a voltage divider circuit, wherein the resistor R5 and the resistor R6 are connected in series, and an output end thereof is connected to a sampling end of the MCU; The high voltage interlock input recovery circuit includes: A voltage divider network including resistors R12 and R13 is used to reduce 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 an equivalent resistance of the high-voltage interlocking circuit, forms a voltage-dividing detection network; And a switch and a protection circuit for realizing current limiting protection.

2. The high-precision, low-power circuit supporting high-voltage interlock resistance detection as claimed in claim 1, characterized in that: The switch and protection circuit include: A switch circuit consisting of a resistor R10 and a transistor Q3; The protection circuit is composed of resistor R9, resistor R11 and transistor Q4.

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

4. A high-voltage interlock resistance detection method based on a high-precision, low-power circuit supporting high-voltage interlock resistance detection according to any one of claims 1 to 3, 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 a high-voltage interlocking loop through a high-voltage interlocking 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 the resistor R2, the equivalent resistance of the high-voltage interlocking loop and the 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.

5. The high voltage interlock resistance detection method according to claim 4, characterized in that: After calculating the equivalent resistance, the calculated equivalent resistance is compared with the preset normal resistance range to determine whether there is an abnormal state such as the high-voltage connector being loose, falling off or poorly connected.

6. The high voltage interlock resistance detection method according to claim 4, characterized in that: During the detection process, the state 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, thereby realizing current limiting protection for the circuit.

7. The high voltage interlock resistance detection method according to claim 4, characterized in that: 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.

8. The high voltage interlock resistance detection method according to claim 4, characterized in that: The voltage division formula is expressed as, V_out=V_in×(R7 / (R2+R7+R_load)) In the formula, V_out is the divided voltage collected by MCU, Rload is the equivalent resistance of the high-voltage interlocking loop, R2 and R7 are the resistance values ​​of resistors R2 and R7 respectively, and V_in is the stable voltage output by LDO.

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