阅读说明：本技术 一种车辆动力电池的接触器诊断/总压采集电路 (Contactor diagnosis/total pressure acquisition circuit of vehicle power battery ) 是由 徐童辉 张红涛 张亚辉 龚珍 于 2019-04-01 设计创作，主要内容包括：本发明涉及一种车辆动力电池的接触器诊断/总压采集电路。该电路包括采样电路和检测支路,该检测支路的第一端连接在当前待检测接触器远离动力电池的一端,该检测支路的第二端连接在非当前待检测接触器靠近动力电池的一端；该检测支路中设有连接第一端的第一开关、连接第二端的第二开关、若干个分压电阻和用于为采样电路的采样点提供正向偏置的参考电压源；第一开关、参考电压源、第一分压电阻、第三分压电阻、第二开关依次串联,参考电压源和第一分压电阻串联后与第二分压电阻并联；采样电路的采样点连接第一分压电阻与第三分压电阻的串联点。该电路不仅实现了接触器的诊断,还可以采集接触器的总压,大大降低了接触器端电压的测量难度。(The invention relates to a contactor diagnosis/total pressure acquisition circuit of a vehicle power battery. The circuit comprises a sampling circuit and a detection branch circuit, wherein the first end of the detection branch circuit is connected to one end, far away from the power battery, of the current contactor to be detected, and the second end of the detection branch circuit is connected to one end, close to the power battery, of the non-current contactor to be detected; the detection branch circuit is internally provided with a first switch connected with a first end, a second switch connected with a second end, a plurality of divider resistors and a reference voltage source for providing forward bias for a sampling point of the sampling circuit; the first switch, the reference voltage source, the first divider resistor, the third divider resistor and the second switch are sequentially connected in series, and the reference voltage source and the first divider resistor are connected in series and then connected in parallel with the second divider resistor; the sampling point of the sampling circuit is connected with the series point of the first voltage dividing resistor and the third voltage dividing resistor. The circuit realizes diagnosis of the contactor, can acquire the total voltage of the contactor, and greatly reduces the measurement difficulty of the terminal voltage of the contactor.)

1. The contactor diagnosis/total pressure acquisition circuit of the vehicle power battery is characterized by comprising a sampling circuit and at least one detection branch circuit, wherein the first end of the detection branch circuit is connected to one end, far away from the power battery, of a contactor to be detected currently, and the second end of the detection branch circuit is connected to one end, close to the power battery, of a contactor not to be detected currently; the detection branch circuit is internally provided with a first switch connected with the first end, a second switch connected with the second end, a plurality of divider resistors and a reference voltage source for providing forward bias for a sampling point of the sampling circuit; the first switch, the reference voltage source, the first divider resistor, the third divider resistor and the second switch are sequentially connected in series, and the reference voltage source and the first divider resistor are connected in series and then connected in parallel with the second divider resistor; and a sampling point of the sampling circuit is connected with a series point of the first voltage dividing resistor and the third voltage dividing resistor.

2. The contactor diagnosis/total pressure acquisition circuit for the vehicle power battery according to claim 1, characterized in that the contactor diagnosis/total pressure acquisition circuit comprises a first detection branch and a second detection branch, and the first detection branch and the second detection branch share the reference voltage source, the first divider resistor, the second divider resistor and the third divider resistor.

3. The vehicle power cell contactor diagnostic/total pressure acquisition circuit according to claim 1 or 2, wherein the first switch and the second switch are relay switches.

4. The contactor diagnosis/total pressure acquisition circuit for the vehicle power battery according to claim 1 or 2, characterized in that the first and second divider resistors have the same resistance value.

5. The vehicle power cell contactor diagnostic/total pressure acquisition circuit of claim 1 or 2, wherein the sampling circuit comprises an ADC circuit.

Technical Field

The invention relates to a contactor diagnosis/total pressure acquisition circuit of a vehicle power battery, and belongs to the technical field of high voltage.

Background

In the application of a high-voltage electrical system, in order to control the on-off of the high-voltage electrical system and ensure the safety of a high-voltage loop, a high-voltage contactor is required to be introduced for controlling the on-off of the loop. In high voltage embodiments, high voltage switches, referred to as high voltage contactors, are provided in the electrical circuit on the high voltage bus between the battery pack and other protected devices, and the battery pack is automatically disconnected from the other rear-end protected devices when the high voltage electrical system is not in use. High voltage contactors use electromagnets to open and close conductive mechanical contacts connected to a high voltage bus, the closing of the mechanical contacts forming a low resistance circuit connection; opening of the mechanical contacts controls the disconnection of the load (i.e., other protected device) from the electrical circuit with the battery pack, thereby disconnecting the battery pack.

The high-voltage contactor is an important electrical control device in an electric vehicle battery system, and the safety state of the high-voltage contactor determines the safety of the whole high-voltage electrical system, so that the on-off state of the high-voltage contactor needs to be diagnosed in the process of vehicle stopping and running so as to ensure that the state of the high-voltage contactor is consistent with the actual requirement.

In the current state diagnosis mode of the high-voltage contactor, a diagnosis circuit is required to be adopted for on-off diagnosis of each contactor, the diagnosis circuit is separated and independent for diagnosis of a positive contactor and a negative contactor, and the diagnosis circuit of the contactor is separated from a total pressure acquisition circuit of a system in general situations, so that the cost of the system circuit is increased, and the circuit is complex. The present diagnostic circuit of a high-voltage contactor is connected in series with a point to be diagnosed by a divider resistor with reference ground, and when the diagnostic circuit is in a working state, high voltage is introduced into the point to be diagnosed (i.e. a sampling point). For example: the chinese patent application publication No. CN 106427614 a, however, has the problem that there are many sampling points, and the positive and negative of the positive contactor and the positive and negative of the negative contactor are not easy to detect, and are easily affected by the virtual voltage.

Disclosure of Invention

The invention aims to provide a contactor diagnosis/total pressure acquisition circuit of a vehicle power battery, which is used for solving the problems of high terminal voltage measurement difficulty and high cost of a positive contactor and a negative contactor in the prior art.

In order to achieve the purpose, the invention provides a contactor diagnosis/total pressure acquisition circuit of a vehicle power battery, which comprises a sampling circuit and at least one detection branch circuit, wherein the first end of the detection branch circuit is connected to one end, far away from the power battery, of a contactor to be detected currently, and the second end of the detection branch circuit is connected to one end, close to the power battery, of a contactor not to be detected currently; the detection branch circuit is internally provided with a first switch connected with a first end, a second switch connected with a second end, a plurality of divider resistors and a reference voltage source for providing forward bias for a sampling point of the sampling circuit; the first switch, the reference voltage source, the first divider resistor, the third divider resistor and the second switch are sequentially connected in series, and the reference voltage source and the first divider resistor are connected in series and then connected in parallel with the second divider resistor; the sampling point of the sampling circuit is connected with the series point of the first voltage dividing resistor and the third voltage dividing resistor.

The beneficial effects are that: the total voltage of the contactor is calculated by collecting the voltage of the sampling point of the sampling circuit, so that the total voltage of the contactor (namely the terminal voltage of the contactor) is collected, the calculated total voltage of the contactor is compared with the voltage of the power battery, the state of the contactor can be obtained, the diagnosis of the contactor is realized, the circuit diagnoses the fault of the contactor on the basis of the total voltage collection, and the reliability of the diagnosis of the contactor is improved. And the circuit can obtain the terminal voltage of the contactor by directly collecting the voltage of the sampling point, thereby greatly reducing the measurement difficulty of the terminal voltage of the contactor and saving the cost.

Furthermore, the contactor diagnosis/total pressure acquisition circuit comprises a first detection branch and a second detection branch, wherein the first detection branch and the second detection branch share a reference voltage source, a first voltage dividing resistor, a second voltage dividing resistor and a third voltage dividing resistor.

The beneficial effects are that: the first detection branch and the second detection branch are respectively used for diagnosing the positive contactor and the negative contactor, and the two detection branches share a reference voltage source, a first voltage dividing resistor, a second voltage dividing resistor and a third voltage dividing resistor, so that the circuit is further simplified, and the cost is saved.

Further, the first switch and the second switch are relay switches.

The beneficial effects are that: the relay switch can more reliably control the opening and closing of the switch, so that the diagnosis result is more accurate.

Further, the first voltage-dividing resistor and the second voltage-dividing resistor have the same resistance value.

The beneficial effects are that: the resistance values of the first voltage-dividing resistor and the second voltage-dividing resistor are the same, so that the calculation process can be simplified, and the diagnosis/total pressure acquisition efficiency is improved.

Further, the sampling circuit includes an ADC circuit.

The beneficial effects are that: the voltage of the sampling point can be accurately acquired through the ADC circuit, so that the total pressure of the obtained contactor is more accurate, and the diagnosis of the contactor is more reliable.

Drawings

FIG. 1 is a circuit diagram of an embodiment 1 of a contactor diagnostic/total pressure acquisition circuit for a vehicle power battery of the present invention;

fig. 2 is a circuit diagram of a contactor diagnosis/total pressure acquisition circuit embodiment 2 of the vehicle power battery of the invention.

Detailed Description

Contactor diagnosis/total pressure acquisition circuit embodiment 1 of vehicle power battery:

the contactor diagnosis/total pressure acquisition circuit of the vehicle power battery provided by the embodiment is designed to diagnose the contactor on the basis of total pressure acquisition of the contactor. In this embodiment, only the positive contactor Relay P is subjected to total pressure collection and diagnosis, a specific circuit is shown in fig. 1, when the positive contactor Relay P (i.e., a high-voltage electrical loop positive control contactor) is detected, the contactor diagnosis/total pressure collection circuit includes a sampling circuit and a detection branch circuit, a first end of the detection branch circuit is connected to one end of the positive contactor Relay P, which is far away from the power battery (here, one end of the detection branch circuit, which is far away from the power battery, is the end of the positive contactor Relay P, which is connected to other protection devices), and a second end of the detection branch circuit is connected to one end of the negative contactor Relay N (high-voltage electrical loop negative control contactor), which is close to the power battery (here, one end of the detection branch circuit, which is close to the.

The detection branch is provided with a first switch SW3 connected with a first end and a second switch SW2 connected with a second end; also provided with a plurality of divider resistors and a sampling point V for the sampling circuit_adcReference voltage source V providing forward bias_refThe plurality of voltage dividing resistors comprise a first voltage dividing resistor R1, a second voltage dividing resistor R2 and a third voltage dividing resistor R3; first switch SW3, reference voltage source V_refA first voltage dividing resistor R1, a third voltage dividing resistor R3 and a second switch SW2 which are connected in series in sequence, and a reference voltage source V_refThe first divider resistor R1 is connected in series and then connected in parallel with the second divider resistor R2; sampling point V of sampling circuit_adcA series point connecting the first divider resistor R1 and the third divider resistor R3.

The principle of the circuit is that the first switch SW3 and the second switch SW2 are closed, and the voltage V of the end, away from the power battery, of the positive pole contactor Relay P can be calculated by sampling the voltage of the sampling point of the circuit_vol-pBy mixing V_vol-pAnd comparing and judging with the voltage of the power battery (namely the battery pack), and further knowing whether the anode contactor Relay P is disconnected or adhered.

In this embodiment, in order to more reliably control the on/off of each switch, each switch is a relay switch, and the relay switches are normally open switches, and the controller shown in fig. 1 is used to control the on/off of each relay switch.

In order to further simplify the calculation process, in the present embodiment, the resistances of the first divider resistor R1 and the second divider resistor R2 are the same. In other embodiments, the resistances of the first divider resistor R1 and the second divider resistor R2 may be different.

In order to more accurately acquire the voltage of the sampling point, in this embodiment, the sampling circuit is an ADC circuit, and the acquisition is completed by an ADC chip.

The specific method for collecting and diagnosing the total pressure of the positive contactor comprises the following steps:

when the circuit carries out positive contactor diagnosis, the ground reference is set as a negative pole (namely BATN) of the battery pack, the positive pole of the battery pack is BATP, the voltage of the battery pack:

V_bat＝BATP–BATN，

when the circuit is used for diagnosis, the number of the positive electrode contactors is not limited, and the number of the positive electrode contactors can be multiple;

1) the controller controls to close the first switch SW3 and the second switch SW2, and the ADC circuit collects the voltage V of the sampling point_adc。

2) The ADC circuit collects the voltage V_adcAnd sending the current to a controller, and calculating by the controller according to the kirchhoff current law, wherein the calculation process is as follows: suppose the point to be measured is V_x，

(V_ref–V_adc)/R1+(V_x–V_adc)/R3＝V_adcR2, wherein R1 ═ R2;

further, it is found that: v_x＝2*R3*V_adc/R2+V_adc–V_ref*R3/R2；

When V is_x＝V_vol-p(total pressure of positive contactor);

V_vol-p＝(2*R3/R2+1)*V_adc–(R3/R2)*V_ref。

3) comparison V_vol-pAnd V_batThe size of (2):

if (V)_bat–V_vol-p)/V_batIf the current is less than 0.05, judging that the positive contactor is adhered; otherwise, judging that the positive contactor is disconnected; 0.05 in the formula is a coefficient, and can be adjusted according to actual conditions.

This embodiment is to total pressure collection and diagnosis carried out to positive contactor, and of course, this detection branch road also can be used for negative contactor's total pressure collection and diagnosis alone, only need connect the one end that detects the branch road in negative contactor connects other protection device's one end, and the other end is connected at power battery's anodal output.

Contactor diagnosis/total pressure acquisition circuit embodiment 2 of vehicle power battery:

the design concept of the contactor diagnosis/total pressure acquisition circuit of the vehicle power battery provided by the embodiment is the same as that of the embodiment 1, except that the embodiment can be used for not only carrying out total pressure acquisition and diagnosis on the positive contactor Relay P, but also carrying out total pressure acquisition and diagnosis on the negative contactor Relay N. The circuit can switch the detection of the positive contactor Relay P and the negative contactor Relay N by switching the switches, and the specific circuit is shown in fig. 2, and the circuit comprises a first detection branch and a second detection branch, wherein the first detection branch is used for detecting the positive contactor Relay P, and the circuit structure is basically the same as that of the circuit in the embodiment 1, except that the first detection branch further comprises a fourth voltage-dividing resistor R4, and the fourth voltage-dividing resistor R4 is connected in series between the third voltage-dividing resistor R3 and the first switch SW 3.

The second detection branch is used for detecting a negative contactor Relay N, the first end of the second detection branch is connected to one end, away from the power battery, of the negative contactor Relay N (hereinafter referred to as a negative contactor) (the end away from the power battery is the end where the negative contactor is connected with other protection devices), and the second end of the detection branch is connected to one end, close to the power battery, of a positive contactor Relay P (hereinafter referred to as a positive contactor) (the end close to the power battery is the positive output end of the power battery).

The second detection branch is provided with a fourth switch SW4 connected with the first end of the branch, a third switch SW1 connected with the second end of the branch and a fifth voltage-dividing resistor R5; the first detection branch and the second detection branch share a reference voltage source V_refA first voltage dividing resistor R1, a second voltage dividing resistor R2, a third voltage dividing resistor R3, a fourth switch SW4, a fifth voltage dividing resistor R5, a third voltage dividing resistor R3526The resistors R3 are in turn connected in series.

The detection principle of the second detection branch is as follows: the fourth switch SW4 and the third switch SW1 are closed, and the voltage V of one end of the negative contactor Relay P far away from the power battery (namely the battery pack) can be calculated through the voltage of the sampling point of the sampling circuit_vol-nBy mixing V_vol-nAnd comparing and judging with the voltage of the power battery, and further knowing whether the negative contactor Relay N is disconnected or adhered.

In this embodiment, in order to more reliably control the on/off of each switch, each switch is a relay switch, and the relay switches are normally open switches, and the controller shown in fig. 2 is used to control the on/off of each relay switch.

In order to further simplify the calculation process, in the present embodiment, the resistances of the first voltage-dividing resistor R1 and the second voltage-dividing resistor R2 are the same, and the resistances of the fourth voltage-dividing resistor R4 and the fifth voltage-dividing resistor R5 are the same. In other embodiments, the resistances of the first voltage-dividing resistor R1 and the second voltage-dividing resistor R2 may be different, and the resistances of the fourth voltage-dividing resistor R4 and the fifth voltage-dividing resistor R5 may be different.

In order to more accurately acquire the voltage of the sampling point, in this embodiment, the sampling circuit is an ADC circuit, and the acquisition is completed by an ADC chip.

The method for collecting and diagnosing the total pressure of the positive and negative contactors is described below.

When the circuit carries out positive contactor diagnosis, the ground reference is the negative pole (BATN) of the battery pack; when the negative contactor diagnosis is carried out, the ground reference is the positive pole (BATP) of the battery pack; voltage of the battery pack:

V_bat＝BATP–BATN，

when the circuit is used for diagnosis, only the diagnosis of the positive electrode contactor or the diagnosis of the negative electrode contactor can be carried out, and the diagnosis cannot be carried out simultaneously.

The total pressure acquisition and diagnosis method of the positive contactor comprises the following steps:

1) the controller controls to close the first switch SW3 and the second switch SW2 and open the fourth switch SW4 and the third switch SW1, and the ADC circuit collects the voltage V of the sampling point_adc。

2) The ADC circuit collects the voltage V_adcAnd sending the current to a controller, and calculating by the controller according to the kirchhoff current law, wherein the calculation process is as follows: suppose the point to be measured is V_x，

(V_ref–V_adc)/R1+(V_x–V_adc)/(R3+R4)＝V_adcR2, wherein R1 ═ R2;

further, it is found that: v_x＝2*(R3+R4)*V_adc/R2+V_adc–V_ref*(R3+R4)/R2；

When V is_x＝V_vol-p(total pressure of positive contactor);

V_vol-p＝(2*(R4+R3)/R2+1)*V_adc–((R4+R3)/R2)*V_ref。

3) comparison V_vol-pAnd V_batThe size of (2):

if (V)_bat–V_vol-p)/V_batIf the current is less than 0.05, judging that the positive contactor is adhered; otherwise, judging that the positive contactor is disconnected; 0.05 in the formula is a coefficient, and can be adjusted according to actual conditions.

The method for total pressure acquisition and diagnosis of the negative contactor is as follows:

1) the controller controls the fourth switch SW4 and the third switch SW1 to be closed, the first switch SW3 and the second switch SW2 to be opened, and the ADC circuit collects the voltage V of the sampling point_adc。

2) The ADC circuit collects the voltage V_adcAnd sending the current to a controller, and calculating by the controller according to the kirchhoff current law, wherein the calculation process is as follows: assuming that electricity is to be measuredPoint location is V_x，

(V_ref–V_adc)/R1＝V_adc/R2+(V_adc+BATP–V_x) (R3+ R5), wherein R1 ═ R2;

further, it is found that: (V)_ref–2V_adc)/R2＝(V_adc+BATP–V_x)/(R3+R5)，

(R3+R5)/R2*V_ref–2*(R3+R5)/R2*V_adc–V_adc＝BATP–V_x，

When V is_x＝V_vol-n(total pressure of negative electrode contactor), bat ═ V_bat，

V_vol-n＝V_bat+(2*(R5+R3)/R1+1)*V_adc–(R5+R3)/R1*V_ref。

3) Comparison V_vol-nAnd V_batThe size of (2):

if (V)_bat–V_vol-n)/V_batIf the current is more than 0.95, judging that the negative contactor is adhered; otherwise, the negative contactor is judged to be disconnected, and 0.95 in the formula is a coefficient and can be adjusted according to the actual condition.

The total pressure acquisition and diagnosis of the positive and negative electrode contactors are completed, and the voltage V-V of the connecting end of the battery pack can be calculated through the total pressure acquisition_vol-p–V_vol-n。

The method described above was verified by simulation.

When carrying out simulation, the selected parameter is V_bat＝200V；R1＝R2＝1kΩ；R3＝R4＝R5＝100kΩ；V_ref2.5V. In addition, the total pressure collection time of the positive and negative electrode contactors and the voltage collection time of the battery pack need to be increased by a time interval t, where t is 100 ms.

According to the simulation of the total pressure acquisition and diagnosis of the positive contactor by the method,

actual simulation sampling to obtain V_adc＝1.7456359V；V_vol-p＝200V；

Obtaining the following result according to the calculation formula of the positive electrode contactor:

V_vol-p＝401*1.7456359V–200*2.5V＝700V–500V＝200V；

theoretical calculation is V_vol-p200V, the actual simulation result V_vol-p＝200V；

After judgment, (V)_bat–V_vol-p)/V_batThe adhesion of positive contactor can be judged for 0, and when actual simulation, positive contactor is also in the adhesion state, can judge that theoretical derivation accords with the actual application.

The total pressure acquisition and diagnosis of the negative contactor are simulated according to the method,

actual simulation sampling to obtain V_adc＝0.74813V；V_vol-n＝0V；

Obtaining the following result according to the calculation formula of the negative contactor:

V_vol-n＝200V+401*0.74813V–200*2.5V＝200V+300V–500V＝0V；

theoretical calculation is V_vol-n0V, the actual simulation result V_vol-n＝0V；

After judgment, (V)_bat-V_vol-n)/V_batThe adhesion of the negative electrode contactor can be judged as 1, and the negative electrode contactor is also in an adhesion state in the actual simulation, so that the theoretical derivation can be judged to accord with the actual application.

The circuit diagnoses the fault of the contactor on the basis of total pressure acquisition, and improves the reliability of contactor diagnosis. The circuit realizes diagnosis of the contactor, can acquire the total pressure of the contactor, greatly reduces the measurement difficulty of the terminal voltage of the contactor, and saves the cost.