CN112255540A - Adhesion fault detection circuit of low-side contactor - Google Patents
Adhesion fault detection circuit of low-side contactor Download PDFInfo
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- CN112255540A CN112255540A CN202011154402.9A CN202011154402A CN112255540A CN 112255540 A CN112255540 A CN 112255540A CN 202011154402 A CN202011154402 A CN 202011154402A CN 112255540 A CN112255540 A CN 112255540A
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- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
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- G01R31/327—Testing of circuit interrupters, switches or circuit-breakers
- G01R31/3271—Testing of circuit interrupters, switches or circuit-breakers of high voltage or medium voltage devices
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Abstract
The invention discloses an adhesion fault detection circuit of a low-side contactor, which comprises a contact detection input loop, wherein a first input end of the contact detection input loop is connected with a positive electrode end BL + of a low-N series battery pack in a power battery system; the second input end and the third input end of the contact detection input loop are respectively connected with the negative pole end HVN of the power battery system and the output end KC1 of the BMS main control chip; the output end of the contact detection input loop is respectively connected with the input end of the contact detection output loop and the second input end of the coil starting detection loop; the output end of the contact detection output loop is connected with the BMS main control chip; the first input end of the coil starting detection circuit is connected with the external coil driving circuit; the output end of the coil starting detection loop is connected with the BMS main control chip. The invention does not need manual investigation, can accurately judge whether the low-side contactor contact has adhesion fault, and improves the detection efficiency.
Description
Technical Field
The invention relates to the technical field of battery management, in particular to an adhesion fault detection circuit of a low-side contactor.
Background
A Battery Management System (BMS), which is a Battery protection device and is also a bridge between a Battery and a load terminal, provides protection functions such as overcharge, overdischarge, and over-temperature for the Battery according to the actual usage state of the Battery monitored on line, and ensures that the Battery is safely used. The battery management system BMS is widely used in various fields such as electric vehicles, communication base stations, and robots.
Taking an electric vehicle as an example, in a vehicle-mounted power battery system (hereinafter referred to as a power battery system), a direct current contactor (hereinafter referred to as a contactor) is generally adopted as a switching device of a high-voltage loop of the battery system, and is a key electrical component in the battery system, and the on-off of the direct current contactor is controlled by a BMS or a vehicle-mounted electronic control system. In practical use, because the impact of heavy current, can take place contactor contact adhesion trouble sometimes for there is high pressure still at power battery system's positive negative pole both ends, will cause very big safety risk to vehicle and operating personnel this moment.
Among them, so cause vehicle and operating personnel safety risk, the reason that exists includes: the BMS does not carry out adhesion detection to the contactor contact, can't detect contactor contact adhesion trouble, consequently can not in time report to the police to remind operating personnel to break high-voltage circuit manually earlier before the maintenance.
In view of the above problems, some prior art schemes adopt an optocoupler chip to directly sample high voltages at two ends of a power battery system to detect a contactor contact adhesion fault, but these schemes can only preliminarily judge the contactor contact adhesion fault but cannot determine whether the contactor contact adhesion fault is true. If need judge whether for contact adhesion trouble, when judging for contact adhesion trouble, still need further manual work to investigate the reason of specific trouble: whether the contacts are not open because the contactor coil power is not turned off or indeed because a contact stick fault has occurred.
In addition, current detection technical scheme is owing to be direct detection high pressure, so the price of the opto-coupler chip of choosing for use is also very high, leads to BMS hardware cost higher.
Disclosure of Invention
The invention aims to provide an adhesion fault detection circuit of a low-side contactor, aiming at the technical defects in the prior art.
Therefore, the invention provides an adhesion fault detection circuit of a low-side contactor, which comprises a contact detection input circuit, a contact detection output circuit, a coil starting detection circuit and a BMS main control chip;
the first input end VP2 of the contact detection input loop is connected with the positive terminal BL + of the low-N series battery pack in the power battery system and is used for receiving the voltage of the positive terminal of the low-N series battery pack in the power battery system;
the low N series battery pack is formed by a plurality of single batteries which are connected in series and close to a low side contactor KL2 in a power battery system;
the negative end B-of the low-N series battery pack is connected with the negative end HVN of the power battery system through a low-side contactor KL 2;
the second input end of the contact detection input loop is connected with the negative pole HVN of the power battery system and used for receiving the voltage of the negative pole HVN of the power battery system;
the third input end of the contact detection input loop is connected with the output end KC1 of the BMS main control chip and is used for receiving and executing a switch control signal KC1 output by the BMS main control chip;
the output end of the contact detection input loop is respectively connected with the input end of the contact detection output loop and the second input end of the coil starting detection loop and used for controlling the on-off of the two loops of the contact detection output loop and the coil starting detection loop;
the output end B of the contact detection output loop is connected with the first input end of the BMS main control chip and used for outputting a contact detection signal B to the BMS main control chip;
a coil starting detection loop, wherein a first input end KLC of the coil starting detection loop is connected with an external coil driving circuit and used for receiving a coil starting signal sent by the external coil driving circuit;
the output end A of the coil starting detection loop is connected with the second input end of the BMS main control chip and used for outputting a coil starting detection signal A to the BMS main control chip;
and the BMS main control chip is used for receiving the contact detection signal B transmitted by the contact detection output loop and receiving the coil starting detection signal A output by the coil starting detection loop, and before high-voltage electrification or after high-voltage low-voltage electrification, if the contact detection signal B of the output end B of the contact detection output loop is at a high level and the coil starting detection signal A of the output end A of the coil starting detection loop is at a low level, the low-side contactor KL2 is judged to have adhesion faults.
Preferably, the BMS master control chip is further configured to send a low-level switch control signal KC1 to a signal input terminal of a switch K1 in the contact detection input circuit after determining that the low-side contactor KL2 has an adhesion fault before the high-voltage power-on or during the high-voltage power-down, and control to turn off the switch K1, so that the adhesion detection is completed.
Preferably, the BMS main control chip is further configured to, when the high voltage is powered on, determine that the low-side contactor KL2 has been activated by the high voltage if both the contact detection signal B of the contact detection output circuit output terminal B and the coil start detection signal a of the coil start detection output circuit output terminal a are at a high level, and otherwise determine that the low-side contactor KL2 has not been activated by the high voltage.
Preferably, the contact detection input circuit comprises a resistor R1, a resistor R2, a resistor R10, a diode D2, a switch K1, a capacitor C1, a resistor R3, a diode D1, an optocoupler Q1, a resistor R4 and a resistor R6, wherein:
the positive electrode end BL + of the low-N series battery pack in the power battery system is connected with one end of a switch K1;
one end of the switch K1 is used as a first input end of the contact detection input circuit;
the 1 st pin of the resistor R1 is connected with the other end of the switch K1;
the signal input end of the switch K1 is used as the third input end of the contact detection input loop and is connected with the output end KC1 of the BMS main control chip;
the 2 nd pin of the resistor R1 is respectively connected with the 1 st pin of the resistor R2, the 1 st pin of the capacitor C1 and the 1 st pin of the resistor R3;
a 2 nd pin of the resistor R2, which is respectively connected with the 2 nd pin of the resistor R10 and the cathode of the diode D2;
the 2 nd pin of the resistor R2 is also respectively connected with the 2 nd pin of the capacitor C1 and the optocoupler Q1 and the anode of the diode D1;
a 1 st pin of the resistor R10 is used as a second input end of the contact detection input circuit and is connected with a negative pole end HVN of the power battery system;
the anode of the diode D2 is connected with the negative end B-of the battery pack;
a 2 nd pin of the resistor R3 is respectively connected with a 1 st pin of the optocoupler Q1 and a cathode of the diode D1;
a 3 rd pin of the optocoupler Q1 is connected with a 2 nd pin of the resistor R4;
the 4 th pin of the optical coupler Q1 is grounded;
the 1 st pin of the resistor R4 is respectively connected with the 2 nd pin of the resistor R6 and the base electrode of the switching tube Q2;
the 1 st pin of the resistor R6 is connected to the 2 nd pin of the resistor R5 and the emitter of the switching tube Q2, respectively.
Preferably, the contact detection output circuit includes: resistance R5, switch Q2 and resistance R7, wherein:
the 1 st pin of the resistor R5 is connected with an external direct-current power supply 5V;
the collector of the switch tube Q2 is respectively connected with the output end B of the contact detection output circuit and the 1 st pin of the resistor R7;
Preferably, the coil start detection circuit includes: resistance R8, switch Q3 and resistance R9, wherein:
the base electrode of the switching tube Q3 is used as the second input end of the coil starting detection loop and is connected with the 3 rd pin of the optocoupler Q1;
the emitter of the switching tube Q3 is connected with the 2 nd pin of the resistor R8;
a 1 st pin of the resistor R8, which is used as a first input terminal of the coil start detection circuit, is connected to the external coil driving circuit, and is used for receiving a coil start signal sent by the external coil driving circuit;
the collector of the switch tube Q3 is respectively connected with the output end A of the coil starting detection loop and the 1 st pin of the resistor R9;
Preferably, before the power battery system is electrified at a high voltage and after the power battery system is electrified at a high voltage, the BMS main control chip judges whether the contact adhesion fault exists in the low-side contactor KL2 according to the combinational logic of the coil starting detection signal a output by the coil starting detection circuit output end a and the contact detection signal B output by the contact detection output circuit output end B, and the judgment conditions are as follows:
when a coil starting detection signal A and a contact detection signal B are both low level, judging that the contact of a low-side contactor KL2 is not adhered;
and secondly, when the coil starting detection signal A is at a low level and the contact detection signal B is at a high level, judging that the contact of the low-side contactor KL2 is adhered.
Preferably, when the power battery system is powered on at a high voltage, the BMS main control chip judges whether the low side contactor KL2 has been activated at a high voltage according to a combination logic of a detection signal B output by the contact detection output circuit output terminal B and a coil start detection signal a output by the coil start detection circuit output terminal a, and the judgment conditions are as follows:
firstly, a coil starting detection signal A and a contact detection signal B are both in high level, and the low-side contactor KL2 is judged to be activated by high voltage;
second, the coil start detection signal a and the contact detection signal B are at low levels, and it is determined that the low-side contactor KL2 is not activated by high voltage.
Compared with the prior art, the adhesion fault detection circuit of the low-side contactor can accurately judge whether the contact of the low-side contactor has the adhesion fault or not without manual inspection, can obviously improve the detection efficiency, and has great practical significance.
In addition, the adhesion fault detection circuit of the low-side contactor provided by the invention has the advantages that the hardware circuit design is scientific, the additional port resource of the BMS main control chip is not occupied, and the high voltage is not directly detected, so that electronic components are universal application models and easy to select, the circuit board occupies small space, the design cost is low, and the circuit board is a technical scheme which is easy to select devices and low in cost. Therefore, the technical scheme of the invention has strong practical value and market popularization value.
Drawings
Fig. 1 is a block diagram illustrating an overall structure of a sticking fault detection circuit of a low-side contactor according to the present invention;
fig. 2 is a specific connection schematic diagram of a contact adhesion detection circuit of a low-side contactor according to the present invention.
Detailed Description
In order to make the technical means for realizing the invention easier to understand, the following detailed description of the present application is made in conjunction with the accompanying drawings and embodiments. It is to be understood that the specific embodiments described herein are illustrative of the relevant application and are not limiting of the application. It should be noted that, for convenience of description, only the portions related to the present application are shown in the drawings.
It should be noted that the embodiments and features of the embodiments in the present application may be combined with each other without conflict. The present application will be described in detail below with reference to the embodiments with reference to the attached drawings.
Referring to fig. 1 and 2, the invention provides an adhesion fault detection circuit of a low-side contactor, which includes a contact detection input circuit 100, a contact detection output circuit 200, a coil start detection circuit 300 and a BMS main control chip 400;
the first input end VP2 of the contact detection input loop 100 is connected with the positive end BL + of the low-N series battery pack in the power battery system and is used for receiving the voltage of the positive end of the low-N series battery pack in the power battery system;
it should be noted that, in a specific implementation, the first input end VP2 of the contact detection input loop 100 is connected to the positive end BL + of the low-N series battery pack in the power battery system;
and N is the number of the single batteries connected in series and is smaller than the total number of the single batteries connected in series in the battery system, and proper N is selected according to the total number of the batteries connected in series in the battery system in practical application.
It should be noted that, referring to fig. 1, the low N-string battery pack is a plurality of series-connected single batteries close to the low-side contactor KL2 in the power battery system, and N series-connected single batteries are arranged between the positive terminal BL + of the low N-string battery pack and the negative terminal B-of the low N-string battery pack, where the negative terminal B-of the low N-string battery pack is connected to the negative terminal HVN of the power battery system through the low-side contactor KL 2.
In the present invention, referring to fig. 1, the positive terminal HVP of the power battery system, i.e. the positive output terminal B + of the power battery system including all the cells connected in series, is shown.
The second input end of the contact detection input circuit 100 is connected with the negative pole end HVN of the power battery system and is used for receiving the voltage of the negative pole end HVN of the power battery system;
it should be noted that, in a specific implementation, the first input end VP2 of the contact detection input circuit 100 is connected to the positive end BL + of the low-N series battery pack in the power battery system, and correspondingly, the second input end of the contact detection input circuit 100 is connected to the negative end HVN of the power battery system, and the contact detection input circuit 100 is configured to receive the voltage of the low-N series battery pack in the power battery system.
The third input end of the contact detection input circuit 100 is connected with the output end KC1 of the BMS main control chip, and is used for receiving and executing a switch control signal KC1 output by the BMS main control chip;
the output end of the contact detection input circuit 100 is connected to the input end of the contact detection output circuit 200 and the second input end of the coil start detection circuit 300, respectively, and is used for controlling the on/off of the two circuits, i.e., the contact detection output circuit 200 and the coil start detection circuit 300.
A contact detection output circuit 200, the output terminal B of which is connected to the first input terminal of the BMS main control chip 400, for outputting a contact detection signal B to the BMS main control chip 40;
a coil start detection circuit 300, a first input end KLC of which is connected to the external coil driving circuit, for receiving a coil start signal sent by the external coil driving circuit, where the coil start signal is a KLC signal;
a coil start detection circuit 300, an output terminal a of which is connected to a second input terminal of the BMS main control chip 400, for outputting a coil start detection signal a to the BMS main control chip 400;
the BMS main control chip 400 is configured to receive the contact detection signal B transmitted by the contact detection output circuit 200 and receive the coil start detection signal a output by the coil start detection circuit 300, and determine that the low-side contactor KL2 has an adhesion fault if the contact detection signal B at the output B of the contact detection output circuit 200 is at a high level and the coil start detection signal a at the output a of the coil start detection circuit 300 is at a low level before high-voltage power-up or after high-voltage power-down.
In specific implementation, the BMS main control chip 400 is further configured to send a low-level switch control signal KC1 to a signal input end of a switch K1 in the contact detection input circuit 100 after judging that the low-side contactor KL2 has an adhesion fault before the power battery system is powered on at a high voltage or when the power battery system is powered off at a high voltage, and disconnect the switch K1, so that adhesion detection is completed.
In specific implementation, the BMS main control chip 400 is further configured to, when the power battery system is powered on at a high voltage, determine that the low-side contactor KL2 has been activated at a high voltage if the contact detection signal B at the output terminal B of the contact detection output circuit 200 and the coil start detection signal a at the output terminal a of the coil start detection circuit 300 are both at a high level, and otherwise determine that the low-side contactor KL2 has not been activated at a high voltage.
It should be noted that, for the high-voltage power-up and the high-voltage power-down, both the high-voltage power-up and the high-voltage power-down are controlled by the BMS main control chip 400, which controls the power-up and the power-down of the power battery system by controlling the on-off of the low-side contact KL2 disposed at the positive terminal of the power battery system.
For the external coil driving circuit, the coil power signal provided by the external coil driving circuit has two states: high and low potentials, wherein the high coil power signal indicates: the contactor coil is energized (i.e., the low side contactor coil is energized), and a low potential coil power signal indicates: the contactor coil has disconnected power (i.e., the low side contactor coil has disconnected power).
It should be noted that the external coil driving circuit is a circuit commonly used in the current BMS technical solution, is a conventional circuit design, is a known circuit structure, and is not described herein again. In the invention, the invention only utilizes the high and low potential signals of the coil power supply provided by the existing external coil driving circuit.
It should be noted that, in fig. 1, the low-N series battery pack and the low-side contactor KL2 are not included in the technical solution of the present invention, and are shown only for facilitating understanding of the technical solution of the present invention.
In order to more clearly understand the technical solution of the present invention, the following takes the detection of the low-side contactor KL2 as an example to illustrate the working principle of the invention:
when the low-side contactor KL2 is detected, a first input end VP2 of the contact detection input circuit 100 is connected with a positive end BL + of a low-N series battery pack in the power battery system, and a second input end is connected with a negative end HVN of the power battery system;
it should be noted that, in a normal state, before the high voltage power-up and after the high voltage power-down, the contact of the low-side contactor KL2 should be opened, the voltage VP2 at the first input end of the contact detection input circuit 100 and the voltage at the second input end of the contact detection input circuit 100 are 0V, the input signal KLC received at the input end of the coil start detection circuit 300 is at a low level (the coil of the low-side contactor KL2 is not powered, and the state of the coil power signal provided by the external coil driving circuit is a low-level coil power signal), the coil start detection signal a output by the output end a of the coil start detection circuit 300 and the contact detection signal B output by the output end B of the contact detection output circuit 200 are at a low level.
Therefore, for the invention, before the power battery system is powered on at high voltage and after the power battery system is powered off at high voltage, in order to detect and judge whether the low-side contactor KL2 works normally, the BMS main control chip 400 judges whether the low-side contactor KL2 has a contact adhesion fault according to the combinational logic of the coil start detection signal a output by the output end a of the coil start detection circuit 300 and the contact detection signal B output by the output end B of the contact detection output circuit 200, and the judgment conditions are as follows:
when a coil starting detection signal A and a contact detection signal B are both low level, judging that the contact of a low-side contactor KL2 is not adhered;
and secondly, when the coil starting detection signal A is at a low level and the contact detection signal B is at a high level, judging that the contact of the low-side contactor KL2 is adhered.
It should be noted that, in a normal state, when the coil is powered on at a high voltage, the input signal KLC of the input terminal KLC of the coil start detection circuit 300 changes from a low level to a high level (because the coil of the low-side contact KL2 is powered on at this time, so that the coil power signal provided by the external coil driving circuit is a high-level coil power signal), the contact of the low-side contact KL2 is pulled in, the voltage between the voltage VP2 of the first input terminal of the contact detection input circuit 100 and the second input terminal is the voltage of the low N series battery pack, so that the contact detection signal B output by the output terminal B of the contact detection output circuit 200 and the coil start detection signal a output by the output terminal a of the coil start detection circuit 300 change from a low level to a high level. When the high voltage is electrified, the coil starting detection signal A and the contact detection signal B are kept in a high level state.
Therefore, for the invention, in order to detect and judge whether the low-side contactor KL2 works normally, when the power battery system is electrified at high voltage, the BMS main control chip 400 judges whether the low-side contactor KL2 is activated at high voltage according to the combinational logic of the detection signal B output by the output terminal B of the contact detection output circuit 200 and the coil start detection signal a output by the output terminal a of the coil start detection circuit 300, and the judgment condition is as follows:
firstly, a coil starting detection signal A and a contact detection signal B are both in high level, and the low-side contactor KL2 is judged to be activated by high voltage;
second, the coil start detection signal a and the contact detection signal B are at low levels, and it is determined that the low-side contactor KL2 is not activated by high voltage.
In the present invention, in terms of specific implementation, referring to fig. 2, the contact detection input circuit 100 includes a resistor R1, a resistor R2, a resistor R10, a diode D2, a switch K1, a capacitor C1, a resistor R3, a diode D1, an optical coupler Q1, a resistor R4, and a resistor R6, where:
the positive pole end BL + of the low N series battery pack in the power battery system is connected with one end of a switch K1;
one end of the switch K1 serves as a first input end of the contact detection input circuit 100;
the 1 st pin of the resistor R1 is connected with the other end of the switch K1;
the signal input end of the switch K1 is used as the third input end of the contact detection input loop 100 and is connected with the output end KC1 of the BMS main control chip;
the 2 nd pin of the resistor R1 is respectively connected with the 1 st pin of the resistor R2, the 1 st pin of the capacitor C1 and the 1 st pin of the resistor R3;
a 2 nd pin of the resistor R2, which is respectively connected with the 2 nd pin of the resistor R10 and the cathode of the diode D2;
the 2 nd pin of the resistor R2 is also respectively connected with the 2 nd pin of the capacitor C1 and the optocoupler Q1 and the anode of the diode D1;
a 1 st pin of the resistor R10 is used as a second input end of the contact detection input circuit 100 and is connected with a negative pole end HVN of the power battery system;
the anode of the diode D2 is connected with the negative terminal B-of the low-N series battery pack;
a 2 nd pin of the resistor R3 is respectively connected with a 1 st pin of the optocoupler Q1 and a cathode of the diode D1;
a 3 rd pin of the optocoupler Q1 is connected with a 2 nd pin of the resistor R4;
the 4 th pin of the optical coupler Q1 is grounded;
the 1 st pin of the resistor R4 is respectively connected with the 2 nd pin of the resistor R6 and the base electrode of the switching tube Q2;
the 1 st pin of the resistor R6 is connected to the 2 nd pin of the resistor R5 and the emitter of the switching tube Q2, respectively.
In the present invention, referring to fig. 2, in a specific implementation, the contact detection output circuit 200 includes: resistance R5, switch Q2 and resistance R7, wherein:
the 1 st pin of the resistor R5 is connected with an external direct-current power supply 5V;
the collector of the switch tube Q2 is respectively connected with the output end B of the contact detection output circuit 200 and the 1 st pin of the resistor R7;
In the present invention, in a specific implementation, referring to fig. 2, the coil start detection circuit 300 includes: resistance R8, switch Q3 and resistance R9, wherein:
the base electrode of the switching tube Q3 is used as the second input end of the coil starting detection loop 300 and is connected with the 3 rd pin of the optocoupler Q1;
the emitter of the switching tube Q3 is connected with the 2 nd pin of the resistor R8;
a 1 st pin of the resistor R8, which is a first input terminal of the coil start detection circuit 300, is used for connecting an external coil driving circuit, and is used for receiving a coil start signal sent by the external coil driving circuit, where the coil start signal is a signal KLC;
the collector of the switch tube Q3 is connected to the output terminal a of the coil start detection circuit 300 and the 1 st pin of the resistor R9, respectively;
In the invention, in terms of specific implementation, for the low-side contactor KL2, before the power battery system is electrified at high voltage and after the power battery system is electrified at high voltage, the normal state should be as follows: the coil power supply of the low-side contactor KL2 is not energized, the signal KLC of the input end KLC of the coil start detection circuit 300 is at a low potential (because the coil of the low-side contactor KL2 is powered off at this time, so that the coil power signal provided by the external coil driving circuit is a low-potential coil power signal, i.e., a low-potential KLC signal), the contact of the low-side contactor KL2 is disconnected, the switch K1 is controlled to be turned off by a KC1 switch control signal (a low level signal according to the present invention) output from the output terminal KC1 of the BMS main control chip 400, the voltage between the first input terminal VP2 and the second input terminal of the contact detection input circuit 100 is 0V, the optical coupler Q1 is cut off, so that the switch tube Q2 and the switch tube Q3 are also cut off, the output end B of the contact detection output loop 200 is pulled down to a low level by the resistor R7, the output a of the coil start detection loop 300 is pulled low by the resistor R9.
The method is characterized in that when adhesion detection is carried out before the power battery system is electrified under high voltage, the switch K1 is firstly closed; when the adhesion detection is finished after high voltage electricity, the switch K1 is finally turned off; at power-up of the high voltage, the switch K1 is always closed.
It should be noted that, when the adhesion detection is finished after the power battery system is charged under a high voltage, the output terminal KC1 of the BMS main control chip 400 outputs a KC1 switch control signal (a low level signal according to the present invention) to the signal input terminal of the switch K1, so as to disconnect the switch K1, with the purpose that: when there is a contact adhesion fault, the contact input detection loop 100 does not consume battery power.
The adhesion fault detection operation before the high-voltage electrification and after the high-voltage electrification of the power battery system is as follows: before high-voltage power-on and after high-voltage power-off, the coil of the low-side contactor KL2 is not electrified, the signal KLC at the input end KLC of the coil start detection circuit 300 is at a low potential (at this time, the state of the coil power signal provided by the external coil driving circuit is a low-potential coil power signal), if the contact of the low-side contactor KL2 is not disconnected due to adhesion, the voltage between the first input end and the second input end of the contact detection input circuit 100 is still equal to the voltage of the low-N series battery pack, after the voltage is divided by the resistor R1 and the resistor R2, the voltage detection end V1 between the resistors R1 and R2 keeps at a high potential, so that the optical coupler Q1 is continuously conducted, the switching tube 2 and the switching tube Q3 are kept in a conducting state, the contact detection signal B at the output end B of the contact detection circuit 200 keeps at a high level, and the coil start detection signal A at the output end A of the, at this time, the BMS main control chip 400 determines that the contact of the low-side contactor KL2 is stuck, and outputs a low-level switch control signal KC1 to turn off the switch K1 after the sticking fault is recorded, and the sticking detection is finished.
It should be noted that when the BMS main control chip 400 determines that the contact adhesion fault exists in the low side contactor KL2, an alarm can be given to an existing vehicle-mounted electronic control system located outside, so that an operator can be timely reminded to manually disconnect the high-voltage loop before maintenance.
Whether the low-side contactor is activated or not during high-voltage electrification of the power battery system is detected as follows: when the high voltage is electrified, a coil of a contactor KL2 is powered on, a signal KLC of an input end KLC of the coil starting detection loop 300 is at a high potential (at the moment, the state of a coil power signal provided by an external coil driving circuit is a coil power signal at the high potential), a contact of a low-side contactor KL2 is pulled in, an output end KC1 of a BMS main control chip outputs a high-level KC1 switch control signal to a signal input end of a switch K1 in the contact detection input loop 100 so as to control to close the switch K1, the voltage between a first input end and a second input end of the contact detection input loop 100 is equal to the voltage of a low-N series battery pack, an optical coupler Q1, a switch tube Q2 and a switch tube Q3 are all conducted, and a coil starting detection signal A of an output end A of the coil starting detection loop and a contact detection signal B of an output end B of the contact detection output loop are both at the, at this time, the BMS main control chip 400 determines that the low side contact KL2 is activated at a high voltage, and the high voltage power-on is successful, otherwise, determines that the low side contact KL2 is not activated at a high voltage, and the high voltage power-on fails.
It should be noted that when the BMS main control chip 400 determines that the low-side contactor KL2 is not activated by the high voltage, it may alarm the existing vehicle-mounted electronic control system located outside and notify that the high voltage power-on fails.
In the present invention, it should be noted that, in terms of specific implementation, the BMS host chip 400 may use a currently commonly used brand, series and model, such as MC9S12 series of NXP, TC265 series of TC2 series of english-flying slush, etc., and the model of the BMS host chip 400 is not within the protection scope of the present invention.
In summary, compared with the prior art, the adhesion fault detection circuit for the low-side contactor provided by the invention can accurately judge whether the adhesion fault occurs to the contact of the low-side contactor without manual inspection, can obviously improve the detection efficiency, and has great practical significance.
In addition, the adhesion fault detection circuit of the low-side contactor provided by the invention has the advantages that the hardware circuit design is scientific, the additional port resource of the BMS main control chip is not occupied, and the high voltage is not directly detected, so that electronic components are universal application models and easy to select, the circuit board occupies small space, the design cost is low, and the circuit board is a technical scheme which is easy to select devices and low in cost. Therefore, the technical scheme of the invention has strong practical value and market popularization value.
The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.
Claims (8)
1. An adhesion fault detection circuit of a low-side contactor is characterized by comprising a contact detection input loop (100), a contact detection output loop (200), a coil starting detection loop (300) and a BMS main control chip (400);
the first input end VP2 of the contact detection input loop (100) is connected with the positive terminal BL + of the low-N series battery pack in the power battery system and is used for receiving the voltage of the positive terminal of the low-N series battery pack in the power battery system;
the low N series battery pack is formed by a plurality of single batteries which are connected in series and close to a low side contactor KL2 in a power battery system;
the negative end B-of the low-N series battery pack is connected with the negative end HVN of the power battery system through a low-side contactor KL 2;
the second input end of the contact detection input circuit (100) is connected with the negative pole end HVN of the power battery system and is used for receiving the voltage of the negative pole end HVN of the power battery system;
the third input end of the contact detection input loop (100) is connected with the output end KC1 of the BMS main control chip and is used for receiving and executing a switch control signal KC1 output by the BMS main control chip;
the output end of the contact detection input loop (100) is respectively connected with the input end of the contact detection output loop (200) and the second input end of the coil starting detection loop (300) and is used for controlling the on-off of the two loops of the contact detection output loop (200) and the coil starting detection loop (300);
the output end B of the contact detection output loop (200) is connected with the first input end of the BMS main control chip (400) and is used for outputting a contact detection signal B to the BMS main control chip (400);
a coil start detection circuit (300), a first input end KLC of which is connected with the external coil drive circuit and is used for receiving a coil start signal sent by the external coil drive circuit;
the output end A of the coil starting detection loop (300) is connected with the second input end of the BMS main control chip (400) and is used for outputting a coil starting detection signal A to the BMS main control chip (400);
and the BMS main control chip (400) is used for receiving a contact detection signal B transmitted by the contact detection output loop (200) and receiving a coil starting detection signal A output by the coil starting detection loop (300), and before high-voltage electrification or after high-voltage low-voltage electrification, if the contact detection signal B at the output end B of the contact detection output loop (200) is at a high level and the coil starting detection signal A at the output end A of the coil starting detection loop (300) is at a low level, the condition that the low-side contactor KL2 has adhesion faults is judged.
2. The sticking fault detection circuit of the low-side contactor according to claim 1, wherein the BMS host control chip (400) is further configured to send a low-level switch control signal KC1 to a signal input terminal of a switch K1 in the contact detection input circuit (100) after determining that the low-side contactor KL2 has a sticking fault before the high-voltage power-up or during the high-voltage power-down, and control to open the switch K1, so that the sticking detection is completed.
3. The sticking fault detection circuit of a low-side contactor according to claim 1, wherein, the BMS main control chip (400) is further configured to determine that the low-side contactor KL2 has been high-voltage activated if the contact detection signal B at the output terminal B of the contact detection output circuit (200) and the coil start detection signal a at the output terminal a of the coil start detection circuit (300) are both high-level when the high voltage is powered on, and otherwise, determine that the low-side contactor KL2 has not been high-voltage activated.
4. The sticking fault detection circuit of a low-side contactor according to claim 1, characterized in that the contact detection input circuit (100) comprises a resistor R1, a resistor R2, a resistor R10, a diode D2, a switch K1, a capacitor C1, a resistor R3, a diode D1, an opto-coupler Q1, a resistor R4 and a resistor R6, wherein:
the positive electrode end BL + of the low-N series battery pack in the power battery system is connected with one end of a switch K1;
one end of the switch K1 is used as a first input end of the contact detection input circuit (100);
the 1 st pin of the resistor R1 is connected with the other end of the switch K1;
the signal input end of the switch K1 is used as the third input end of the contact detection input loop (100) and is connected with the output end KC1 of the BMS main control chip;
the 2 nd pin of the resistor R1 is respectively connected with the 1 st pin of the resistor R2, the 1 st pin of the capacitor C1 and the 1 st pin of the resistor R3;
a 2 nd pin of the resistor R2, which is respectively connected with the 2 nd pin of the resistor R10 and the cathode of the diode D2;
the 2 nd pin of the resistor R2 is also respectively connected with the 2 nd pin of the capacitor C1 and the optocoupler Q1 and the anode of the diode D1;
a 1 st pin of the resistor R10 is used as a second input end of the contact detection input circuit (100) and is connected with a negative pole end HVN of the power battery system;
the anode of the diode D2 is connected with the negative end B-of the battery pack;
a 2 nd pin of the resistor R3 is respectively connected with a 1 st pin of the optocoupler Q1 and a cathode of the diode D1;
a 3 rd pin of the optocoupler Q1 is connected with a 2 nd pin of the resistor R4;
the 4 th pin of the optical coupler Q1 is grounded;
the 1 st pin of the resistor R4 is respectively connected with the 2 nd pin of the resistor R6 and the base electrode of the switching tube Q2;
the 1 st pin of the resistor R6 is connected to the 2 nd pin of the resistor R5 and the emitter of the switching tube Q2, respectively.
5. The sticking fault detection circuit of a low side contactor as claimed in claim 4, wherein the contact detection output circuit (200) comprises: resistance R5, switch Q2 and resistance R7, wherein:
the 1 st pin of the resistor R5 is connected with an external direct-current power supply 5V;
the collector electrode of the switch tube Q2 is respectively connected with the output end B of the contact detection output circuit (200) and the 1 st pin of the resistor R7;
pin 2 of resistor R7 is connected to ground.
6. The sticking fault detection circuit of a low side contactor as claimed in claim 5, wherein said coil start detection loop (300) comprises: resistance R8, switch Q3 and resistance R9, wherein:
the base electrode of the switching tube Q3 is used as the second input end of the coil starting detection loop (300) and is connected with the 3 rd pin of the optocoupler Q1;
the emitter of the switching tube Q3 is connected with the 2 nd pin of the resistor R8;
a 1 st pin of the resistor R8, which is used as a first input terminal of the coil start detection circuit (300), is used for connecting an external coil driving circuit, and is used for receiving a coil start signal sent by the external coil driving circuit;
the collector of the switch tube Q3 is respectively connected with the output end A of the coil starting detection loop (300) and the 1 st pin of the resistor R9;
pin 2 of resistor R9 is connected to ground.
7. The adhesion fault detection circuit of the low-side contactor according to claim 5, wherein before the power battery system is powered on at a high voltage and after the power battery system is powered off at a high voltage, the BMS main control chip (400) judges whether the contact adhesion fault of the low-side contactor KL2 exists according to the combinational logic of the coil start detection signal A output by the output end A of the coil start detection circuit (300) and the contact detection signal B output by the output end B of the contact detection output circuit (200), and the judgment conditions are as follows:
when a coil starting detection signal A and a contact detection signal B are both low level, judging that the contact of a low-side contactor KL2 is not adhered;
and secondly, when the coil starting detection signal A is at a low level and the contact detection signal B is at a high level, judging that the contact of the low-side contactor KL2 is adhered.
8. The adhesion fault detection circuit of the low-side contactor according to claim 5, characterized in that, when the power battery system is powered on at high voltage, the BMS main control chip (400) judges whether the low-side contactor KL2 has been activated at high voltage according to the combinational logic of the detection signal B output by the output end B of the contact detection output circuit (200) and the coil start detection signal A output by the output end A of the coil start detection circuit (300), and the judgment conditions are as follows:
firstly, a coil starting detection signal A and a contact detection signal B are both in high level, and the low-side contactor KL2 is judged to be activated by high voltage;
second, the coil start detection signal a and the contact detection signal B are at low levels, and it is determined that the low-side contactor KL2 is not activated by high voltage.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202011154402.9A CN112255540A (en) | 2020-10-26 | 2020-10-26 | Adhesion fault detection circuit of low-side contactor |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202011154402.9A CN112255540A (en) | 2020-10-26 | 2020-10-26 | Adhesion fault detection circuit of low-side contactor |
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| CN112255540A true CN112255540A (en) | 2021-01-22 |
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| CN202011154402.9A Pending CN112255540A (en) | 2020-10-26 | 2020-10-26 | Adhesion fault detection circuit of low-side contactor |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115963393A (en) * | 2022-12-28 | 2023-04-14 | 江苏纳通能源技术有限公司 | Contact adhesion misjudgment and contact adhesion detection circuit and method |
-
2020
- 2020-10-26 CN CN202011154402.9A patent/CN112255540A/en active Pending
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115963393A (en) * | 2022-12-28 | 2023-04-14 | 江苏纳通能源技术有限公司 | Contact adhesion misjudgment and contact adhesion detection circuit and method |
| CN115963393B (en) * | 2022-12-28 | 2024-01-05 | 江苏纳通能源技术有限公司 | Contact adhesion misjudgment and contact adhesion detection circuit and method |
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