CN210690758U

CN210690758U - Detection circuit

Info

Publication number: CN210690758U
Application number: CN201921415318.0U
Authority: CN
Inventors: 王晓东; 习清平; 董立伟; 周玲燕
Original assignee: Anhui Udan Technology Co ltd
Current assignee: Anhui Udan Technology Co ltd
Priority date: 2019-08-28
Filing date: 2019-08-28
Publication date: 2020-06-05
Anticipated expiration: 2029-08-28

Abstract

The utility model discloses a detection circuit belongs to the high-voltage relay field. Aiming at the defects that the relay in the prior art can not be effectively detected after being adhered, overcharge or overdischarge is easily caused, safety accidents are caused, the excitation voltage is too high in a solving mode, the small resistor has large power consumption in use, the current sensor has high cost, large volume and the like, the utility model provides a detection circuit, which applies the excitation voltage to the negative pole of the relay and sets a sampling resistor, the negative pole voltage of the circuit is measured by utilizing the resistance sampling voltage division principle, and the measured value is compared with the reference value to judge whether the relay is adhered or not; simultaneously use pressure differential calculation to judge whether the relay adheres at the anodal return circuit of relay, the utility model discloses can realize can be under the condition of not closed other relays, the adhesion of short-term test discharge relay and charging relay, and the detection mode is simple and convenient, and is with low costs, easily realizes.

Description

Detection circuit

Technical Field

The invention relates to the field of high-voltage relays, in particular to a detection circuit.

Background

With the increasing application of new energy vehicles, the high-voltage relay is used for controlling the on-off of a high-voltage loop, the reliability of the high-voltage relay is very important, and after the relay is adhered, a discharging/charging loop cannot be effectively cut off, so that the over-charging or over-discharging of a battery is caused, and safety accidents are caused.

The relay adhesion, especially the detection of the cathode relay adhesion, generally adopts the method of a relay with an auxiliary contact, increases the cost and has low reliability; or judging the adhesion of the relay by using a resistance voltage division measurement method and a differential pressure judgment method, as shown in fig. 1, the total battery pressure is V1, the voltage on the contact of the total positive relay is V2, the voltage on the contact of the quick charge relay is V3, and whether the adhesion of the total positive relay and the quick charge positive relay occurs or not can be judged according to the voltage of V2-V1 or V3-V1. Is a commonly used judgment method at present.

The pressure difference method is effective in adhesion detection of the pre-charging/charging positive relay, but adhesion of the negative pole of the charging negative relay to the negative pole of the battery cannot be judged, and due to the fact that no voltage exists between V4 and V5, the adhesion cannot be judged immediately after the battery is powered on, excitation voltage is applied to a contact of the discharging negative relay generally in a mode of closing the pre-charging relay/quick-charging positive relay, and whether the total negative relay/quick-charging negative relay is adhered or not is judged by judging the change of the voltage on V5. However, this method has its own drawbacks: 1. the power-on speed is reduced, and the time is required for closing the relay; 2. if the negative relay is already stuck, closing the positive relay may cause the positive relays to stick together.

Chinese patent application, application No. 201410783812.8, published as 2015, 8.12.3 discloses a detection device for a relay, wherein a relay control circuit comprises a negative relay, a positive relay, a pre-charging resistor and a motor. The detection device comprises a detection circuit and a controller, wherein the detection circuit comprises a first resistor of which the first end is connected with the second end of the cathode relay; the first switch is connected with the second end of the first resistor at the first end; the first current sensor is connected with the first end of the negative relay at the first end; the controller is used for controlling the first switch to be closed when the negative relay is closed or disconnected, and judging whether the state of the negative relay is normal or not according to the current collected by the first current sensor. The relay detection device of the embodiment of the invention can find the fault of the relay in time, so that a battery management system or a whole vehicle management system makes a decision in time according to the fault, the safety of a power battery is ensured, and the aim of protecting the safety of personnel is fulfilled at the same time, wherein the added excitation voltage is from the total voltage of the battery system: the voltage is as high as several hundred V, and the voltage-resistant requirement of K1 is high. The current sensor itself is expensive and bulky, and if a detectable current is to be formed, the resistance of R1 needs to be small and power consumption large.

Disclosure of Invention

1. Technical problem to be solved

Can not effectual cutoff circuit behind the relay adhesion to exist among the prior art, arouse easily that overcharge or overdischarge arouse the incident, solution mode excitation voltage is too high, and the small resistance uses the consumption big, and current sensor is with high costs, and is bulky etc. not enough, the utility model provides a method of detection relay adhesion, it can realize can not being closed under the condition of other relays, and the adhesion of negative pole relay and charging relay that discharges of short-term test, and the detection mode is simple and convenient, and is with low costs, easily realizes.

2. Technical scheme

The purpose of the utility model is realized through the following technical scheme.

A detection circuit comprises charging relays K1 and K4, discharging relays K2 and K3, a charger, a motor controller and a power supply; the motor controller is connected with the discharging relays K2 and K3, the charger is connected with the charging relays K1 and K4, the discharging relays are controlled by the motor controller in the input loop and the output loop, and the charging relays are controlled by the charger. Relays K1 and K2 are connected with the positive pole of a power supply, relays K3 and K4 are connected with the negative pole of the power supply, relays K3 and K4 are respectively connected with sampling resistors, and the other ends of the sampling resistors are connected with excitation voltage. In the operation, an engineer judges whether the relay is adhered or not by detecting the voltage value of the negative electrode of the power supply after applying the excitation voltage, the sampling resistor has a sampling effect on the excitation voltage, and the voltage of the negative electrode resistor of the circuit can be obtained by obtaining the current value according to the sampling resistor. The voltage of detection circuitry negative pole compares with the reference voltage who calculates, judges whether adhesion of power negative pole relay, has solved circuit negative pole relay and has not had voltage, can't judge at once whether adhesion of relay after the electricity, and the tradition is exerted voltage for negative pole relay through closed positive relay mode and is judged whether adhesion power-on speed is slow, if negative pole relay adhesion still can arouse the circumstances of anodal relay adhesion simultaneously, direct application excitation voltage at the negative pole detects, and it is convenient with low costs to detect, and the reliability is high.

Furthermore, the excitation voltage is a low-voltage signal obtained by converting DC/DC of a high-voltage power supply, and the negative pole of the excitation voltage is connected with the negative pole of the power supply. The excitation voltage comes from DC/DC conversion, the voltage is lower, no switch is needed when the voltage is applied, the requirement on the withstand voltage of the relay is low, and the cost is low. The excitation voltage is applied to the relay output loop, and the polarity of the excitation voltage is the same as that of the power supply, so that the excitation voltage does not conflict with the power supply.

Furthermore, the range of the excitation voltage is 5-36V, and the excitation voltage is converted by DC/DC high voltage and low voltage and can be any value in 5-36V.

Furthermore, the circuit is also provided with resistors R4, R5, R6 and R7, the resistors R5 and R7 are connected in series and then connected with a relay K3 in parallel, and the sampling resistor R9 is connected with the resistors R4 and R6; the resistors R4 and R6 are connected in series and then connected in parallel with the relay K4, and the sampling resistor R8 is connected with the resistors R5 and R6. Assuming that the excitation voltage is V0, V0 is connected with a sampling resistor and then applied to a negative circuit of the circuit, and the reference voltages at two ends of the negative resistors R4 and R5 of the circuit are defined as V4 and V5 through the sampling voltage division of the sampling resistor and the circuit resistor, V4 is defined as V0R 4/(R4+ R8), and V5 is defined as V0R 5/(R5+ R9). If the relay contacts are stuck, the reference voltages at two ends of the resistors R4 and R5 are V4 'and V5', then V4 '═ V0R 4// R6/(R8+ R4// R6), V5' ═ V0R 5// R7/(R9+ R5// R7), and the resistance value after the resistors are connected in parallel is smaller than that of any parallel resistor, namely R4// R6< R4, R5// R7< R5, so V4 '< V4, and V5' < V5. Theoretically, the corresponding relay adhesion can be judged when the detection voltage is lower than V4 or V5, in order to eliminate interference information in the actual process, a threshold value slightly lower than V4 and V5 is set, and when the detection voltages V4 'and V5' are lower than the threshold value, the corresponding relay adhesion is judged.

Further, the resistors R4 and R5, R6 and R7, and R8 and R9 have the same resistance. Generally, for convenience in measurement and calculation, resistors R4 and R5, R6 and R7, and R8 and R9 are resistors with the same resistance, because excitation voltages are the same, sampling resistors connected with different relays are the same as the relay resistors, detection and calculation processes are simplified, and time cost in the detection process of engineers is saved.

Furthermore, the relay connected with the positive pole of the power supply in the circuit is a positive relay. In general, a relay connected to the positive pole of a power supply is called a positive relay, and the positive relay controls a circuit input circuit.

Furthermore, the relay connected with the negative pole of the power supply in the circuit is a negative relay. In general, a relay connected to the negative electrode of a power supply is referred to as a negative relay. And the negative relay control circuit outputs a loop. The positive relay and the negative relay work independently and do not interfere with each other.

Furthermore, the circuit is also provided with resistors RB1, RB2 and RB3, wherein the two ends of the resistor RB1 are respectively connected with the positive pole and the negative pole of a power supply, the two ends of the resistor RB2 are connected with the discharging relay K2 and the negative pole of the power supply, and the two ends of the resistor RB3 are connected with the charging relay K1 and the negative pole of the power supply. The voltage V1 at the two ends of the resistor RB1 is the total voltage of the battery; the voltage V2 at the two ends of RB2 is the voltage on the contact of the discharge relay K2; the voltage V3 at the two ends of RB3 is the voltage on the contact of the charging relay K1; whether the relay is stuck is judged through the differential pressure calculation of V1, V2 and V3. Whether the discharging relay K2 and the charging relay K1 are stuck or not can be judged according to the sizes of V2-V1 or V3-V1, and if the voltage difference between V2 and V1 is smaller than a second set value and the voltage difference between V3 and V1 is smaller than a third set value, the relay is judged to be stuck.

Further, the circuit also comprises a pre-charging relay K5, a pre-charging relay K5 and a discharging relay K2 which are connected in parallel. The pre-charging relay K5 is connected with the positive pole of the power supply, whether adhesion exists can be judged according to a pressure difference method, and due to the fact that the pre-charging relay K5 is in parallel connection with the discharging relay K2, the fact that the K2 and the K5 are integrally connected or not can be judged, which relay adhesion cannot be judged, and the adhesion is detected and then the pre-charging relay or the discharging relay is further checked to be the adhesion.

Furthermore, a high-voltage circuit maintenance switch MSD is arranged in the circuit power supply, and in order to ensure safety when the high-voltage power supply circuit is maintained, the switch for disconnecting the power supply of the high-voltage system in a manual mode is used as the power supply maintenance protection switch, and simultaneously, the MSD also plays a role in short-circuit protection, so that safety and reliability guarantee are provided for circuit maintenance. Because the utility model discloses the power is high voltage power supply, sets up switch MSD and guarantees the reliability of circuit. The excitation voltage in the corresponding circuit is low voltage after conversion, and a protection switch is not required to be additionally arranged.

The utility model relates to a detection circuitry passes through voltage partial pressure after circuit negative pole relay applys excitation voltage, detects the negative pole voltage and judges whether the relay adhesion, and detection method is simple and convenient, and is with low costs, and the low power dissipation further improves the circuit reliability, uses the differential pressure method at circuit positive pole relay to detect whether the adhesion, and is convenient high-efficient. The utility model discloses exert excitation voltage and battery and be born altogether, exert total burden relay contact and fill burden relay contact soon, excitation voltage uses the low-voltage signal by high-voltage after DC conversion, and voltage signal is little, and is not high to the withstand voltage requirement of relay, does not need the switch, and is with low costs.

3. Advantageous effects

Compared with the prior art, the utility model has the advantages of:

the method judges whether the cathode of the relay is adhered or not by detecting the voltage of the cathode of the system after applying the excitation voltage after DC/DC conversion in the circuit, the detection is quick and accurate, the judgment of whether the cathode of the relay is adhered or not in the circuit of the relay is carried out at low cost, the detection method is simple, and the reliability of the system is improved. The utility model discloses the outside excitation voltage who applys comes from the low pressure signal after the conversion, and the voltage range can all be selected from the 5-36V scope, and it is lower to apply excitation voltage, does not need the switch, and is low to the withstand voltage requirement of relay, and the voltage point that detects simultaneously is the total negative pole voltage point of system, and is simple and convenient during the testing voltage.

Drawings

FIG. 1 is an electrical structure diagram for determining the relay adhesion by a pressure difference method;

fig. 2 is an electrical structure diagram of the present invention.

Detailed Description

The invention is described in detail below with reference to the drawings and specific examples.

Example 1

A detection circuit is shown in figure 1 and comprises charging relays K1 and K4, discharging relays K2 and K3, a charger, a motor controller and a power supply; the motor controller is connected with the discharging relays K2 and K3, and the charger is connected with the charging relays K1 and K4; relays K1 and K2 are connected with the positive pole of the power supply, and relays K3 and K4 are connected with the negative pole of the power supply.

Fig. 1 shows that whether the relays K1, K2, and K5 are adhered is judged by a differential pressure method, a relay control circuit is provided with resistors RB1, RB2, and RB3, two ends of RB1 are respectively connected with a positive electrode and a negative electrode of a power supply, and a voltage V1 at two ends of RB1 is total battery pressure; the two ends of RB2 are connected with a discharging relay K2 device and a power supply cathode, and the voltage V2 at the two ends of RB2 is the voltage on a contact of a discharging relay K2; the two ends of RB3 are connected with a charging relay K3 and a power supply cathode, and the voltage V3 at the two ends of RB3 is the voltage on a contact of the charging relay K3; RB1, RB2 and RB3 are equal in resistance value, whether the discharging relay K2 and the charging relay K1 are adhered or not can be judged through the sizes of V2-V1 or V3-V1, and if the numerical values of V2-V1 or V3-V1 are smaller than a preset value, the corresponding relays are judged to be adhered. Because the pre-charging relay K5 and the discharging relay K2 are in parallel connection, the pre-charging relay K5 or the discharging relay K2 can be further checked after the adhesion is detected, and only the adhesion can be judged, and the adhesion can not be judged.

As shown in fig. 1 and 2, the circuit is further provided with resistors R4, R5, R6 and R7, the resistors R5 and R7 are connected in series and then connected in parallel with the relay K3, and the sampling resistor R9 is connected with both the resistors R4 and R6; the resistors R4 and R6 are connected in series and then connected in parallel with the relay K4, the sampling resistor R8 is connected with the resistors R5 and R6, and the other end of the sampling resistor is connected with excitation voltage. The power supply in the circuit is provided with a high-voltage circuit maintenance switch MSD, the switch MSD is used for manually disconnecting the power supply of a high-voltage system in order to ensure safety when the high-voltage power supply circuit is maintained, and the MSD is used as a power supply maintenance protection switch and also plays a role in short-circuit protection at the same time, so that the safety and reliability guarantee is provided for the maintenance of the circuit.

One end of the relay K3 or K4 is connected with the negative pole of the power supply, and the other end is connected with the corresponding positive relay K1 or K2. As shown in fig. 2, 12V excitation voltage which is negative with the power supply is applied to both the discharging relay K3 and the charging relay K4, the excitation voltage is applied to the negative circuit of the circuit after being connected with the sampling resistor, and for the convenience of calculation and detection, the resistors R4 and R5, R6 and R7, and R8 and R9 are usually the same in resistance. After the excitation voltage is applied, the voltage reference value V4-V5-12-R4/(R4 + R8) -12-R5/(R5 + R9) is applied to both ends of R4 and R5.

Generally, R8, R9 and R6, R7 have the same resistance, and the divided voltage values of R8, R9 and R4, R5 are approximately equal to the full-scale voltage value of ADC. If the relay K3 or K4 is connected in a sticky manner, which is equivalent to that R4 and R6 are connected in parallel in the circuit, R6 and R6 are connected in parallel, and R6 or R6 is connected in series with the parallel resistor, at this time, the voltage V6 ' across the R6 and R6 is 12R 6// R6/(R6 + R6// R6), and the resistance value after the resistors are connected in parallel is smaller than any parallel resistor, namely, R6// R6< R6, so V6 ' < V6, and V6 ' < V6. Under the condition that resistance values of resistors R4-R9 are known, voltages at two ends of R4 and R5 are detected and compared with a calculation reference voltage to judge whether the relay K3 or K4 is adhered or not, a threshold value is set during detection, if the threshold values of V4 and V5 are set to be 3V when the relay is not adhered, the voltage of V4 and V5 after the relay is adhered is calculated to be 1.5V, and the threshold value is set to be 2.25V, whether the charging relay K4 and the discharging relay K3 are adhered or not can be judged quickly, the relay adhesion can be judged if the voltage is lower than 3V theoretically, and in order to eliminate interference information in the actual process, the threshold value is set to be slightly lower, for example, 2.25V.

In the embodiment, an external excitation voltage is applied, the excitation voltage is from DC/DC conversion, the range can be any number in 5-36V, the voltage is lower, no switch is needed when the voltage is applied, the requirement on the withstand voltage of the relay is low, and the cost is low; the resistance value of the resistor in the circuit is low, and the power consumption is low; meanwhile, the detected voltage point is the total negative voltage point of the system, and the voltage value is detected simply and conveniently.

The invention and its embodiments have been described above schematically, without limitation, in other specific forms without departing from the spirit or essential characteristics thereof. The embodiment shown in the drawings is only one of the embodiments of the invention, the actual structure is not limited to the embodiments, and any reference signs in the claims shall not limit the claims. Therefore, if a person skilled in the art receives the teachings of the present invention, without inventive design, a similar structure and an embodiment to the above technical solution should be covered by the protection scope of the present patent. Furthermore, the word "comprising" does not exclude other elements or steps, and the word "a" or "an" preceding an element does not exclude the presence of a plurality of such elements. Several of the elements recited in the product claims may also be implemented by one element in software or hardware. The terms first, second, etc. are used to denote names, but not any particular order.

Claims

1. A detection circuit comprises charging relays K1 and K4, discharging relays K2 and K3, a charger, a motor controller and a power supply; the motor controller is connected with the discharging relays K2 and K3, and the charger is connected with the charging relays K1 and K4; relays K1 and K2 connect the positive pole of the power supply, and relays K3 and K4 connect the negative pole of the power supply, and its characteristics are that relays K3 and K4 connect the sampling resistance respectively, and the excitation voltage is connected to the sampling resistance other end.

2. The detection circuit of claim 1, wherein the excitation voltage is a low voltage signal obtained by DC/DC conversion of a high voltage power supply, and the negative pole of the excitation voltage is connected to the negative pole of the power supply.

3. A detection circuit according to claim 2, characterized in that the excitation voltage is in the range of 5-36V.

4. The detection circuit according to claim 3, characterized in that the circuit is further provided with resistors R4, R5, R6 and R7, the resistors R5 and R7 are connected in series and then connected in parallel with a relay K3, and the sampling resistor R9 is connected with the resistors R4 and R6; the resistors R4 and R6 are connected in series and then connected in parallel with the relay K4, and the sampling resistor R8 is connected with the resistors R5 and R6.

5. The detection circuit of claim 4, wherein the resistors R4 and R5, R6 and R7, and R8 and R9 have the same resistance.

6. A test circuit according to claim 5, wherein the relay in the circuit connected to the positive pole of the power supply is a positive relay.

7. A test circuit as claimed in claim 6, wherein the relay in the circuit connected to the negative pole of the power supply is a negative relay.

8. The detection circuit according to claim 7, characterized in that the circuit is further provided with resistors RB1, RB2 and RB3, wherein the two ends of the resistor RB1 are respectively connected with the positive pole and the negative pole of a power supply, the two ends of the resistor RB2 are connected with the discharging relay K2 and the negative pole of the power supply, and the two ends of the resistor RB3 are connected with the charging relay K1 and the negative pole of the power supply.

9. The detection circuit according to claim 8, wherein the circuit further comprises a pre-charge relay K5, K5 connected in parallel with a discharge relay K2.

10. The detection circuit according to claim 9, wherein a high voltage circuit maintenance switch MSD is provided in the circuit power supply.