TVS state acquisition circuit
By introducing transistors and voltage divider resistors into the TVS tube state acquisition circuit, and using the voltage divider voltage value to determine the TVS tube state, the problem of inability to accurately distinguish short circuit and clamp voltage state in the prior art is solved, and efficient and accurate state is achieved Judgment and low power consumption circuit design.
Patent Information
- Application Number
- CN202323647529.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2023-12-29
- Publication Date
- 2025-02-25
- Estimated Expiration
- 2033-12-29
AI Technical Summary
The existing TVS tube state acquisition circuit cannot accurately distinguish between TVS tube short circuit and clamp voltage, and requires additional operating voltage, which increases power consumption and poses a risk of false triggering.
Using the combination of transistor and voltage divider resistor, the switching characteristics of transistors and the principle of resistive voltage division is used to determine the state of the TVS tube by collecting the voltage divider voltage value, avoiding the use of additional working voltage.
It realizes accurate judgment of the state of TVS tube, reduces power consumption, simplifies circuits, and reduces the dependence of software algorithms, and improves the accuracy and reliability of state judgment.
Smart Images
Figure CN222529443U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the technical field of power management, in particular to a TVS state acquisition circuit. Background Art
[0002] When the BMS (battery management system) cuts off the main circuit MOS tube, since the external inductor stores energy, it is necessary to provide the inductor with a freewheeling circuit to release the energy. Generally, the TVS tube is connected in series or parallel to provide a release path for the energy. Before controlling the main circuit MOS tube (metal-oxide semiconductor field effect transistor) to be turned on or off, it is necessary to judge the state of the TVS tube in advance to determine whether the TVS tube is working normally. For example, when the TVS tube is short-circuited, the circuit is abnormal, and the main circuit MOS tube must be turned off. Otherwise, the short circuit of the TVS tube causes the battery pack to be short-circuited, causing a circuit failure; for example, only when the TVS tube is cut off can the main circuit MOS tube be turned on or off according to the needs of the BMS; for example, after the main circuit MOS tube is operated, if the TVS tube should generate a clamping voltage but does not generate it, it means that the circuit is faulty and the main circuit MOS tube must be turned off.
[0003] From the above description, we know that the BMS needs to collect the status of the TVS tube in real time to determine whether the control and circuit response are correct. Therefore, it is very important to accurately obtain the status of the TVS tube.
[0004] An existing TVS tube state acquisition circuit is as follows: Figure 1 As shown, the basic principle is as follows: inject the signal source, collect the output signal, combine the characteristics of the TVS tube and the application scenario, and use the logic of the input and output signals to make judgments. Taking TVS tube 1 as an example, the TVS tube has three states: short-circuit state, cut-off state and state of generating clamping voltage. The short-circuit state means that the TVS tube is equivalent to the wire, and the branch where the TVS tube is located is conductive; the TVS cut-off state means that the TVS tube is disconnected, and the branch where the TVS tube is located is disconnected; the state of generating clamping voltage means that the voltage at both ends of the TVS tube is clamped. When the TVS tube is short-circuited, Vbat=V2. Since Vbat>Vin, the diode cannot be turned on, so the collected output voltage Vout is equal to the input voltage Vin; when the TVS tube is in the cut-off state, V2=0V, the diode is turned on, and according to the resistor voltage division, Vout=R2 / (R1+R2)Vin; when the TVS tube generates a clamping voltage, V2=Vbat-Vclamp, where Vclamp is the clamping voltage of the TVS tube, V2>Vin, the diode is not turned on, and at this time Vout=Vin.
[0005] In the three states, the output voltage Vout corresponding to the TVS tube short circuit and the TVS tube generating a clamping voltage is equal to the input voltage Vin. It is impossible to distinguish between the two states of the TVS tube short circuit and the TVS tube generating a clamping voltage. It is also necessary to add an additional judgment program inside the microprocessor unit to distinguish between the two states of the TVS tube short circuit and the TVS tube generating a clamping voltage. In addition, the scheme needs to inject a signal source, which always requires an additional working voltage Vin, increasing power consumption, and the additional injected signal source will cause false triggering of peripheral devices in certain situations, such as false triggering of the main circuit MOS, etc., and there is a risk of TVS state acquisition error and MOS tube switch control failure. Summary of the invention
[0006] In view of the problems existing in the above TVS status diagnosis circuit, a transistor is introduced, and a TVS status acquisition circuit is proposed by using the switching characteristics of the transistor and the principle of resistor voltage division. The status of the TVS tube can be directly judged by the voltage division value of the resistor in the circuit without introducing additional working voltage.
[0007] In order to achieve the above-mentioned utility model purpose, the utility model provides the following technical solutions:
[0008] A TVS state acquisition circuit includes a transistor and a voltage dividing resistor.
[0009] The base of the transistor is connected to the anode of the TVS through a first resistor, the collector of the transistor is connected to the anode of the TVS through a second resistor, and the cathode end of the TVS has a working voltage; a voltage-dividing resistor is connected in series between the emitter of the transistor and the ground, and a voltage-dividing voltage value is output from one end of the voltage-dividing resistor, and the state of the TVS is determined according to the voltage-dividing voltage value.
[0010] Furthermore, the states of the TVS include a short-circuit state, a cut-off state, and a state of generating a clamping voltage.
[0011] Furthermore, the anode voltage of the TVS is greater than the conduction voltage between the base and emitter of the transistor.
[0012] As a preferred solution, the voltage-dividing resistor includes a plurality of resistors connected in series.
[0013] Furthermore, the divided voltage value is a voltage value of a sampling point between the divided voltage resistors.
[0014] As a preferred solution, the voltage-dividing resistor includes two resistors connected in series.
[0015] Furthermore, the divided voltage value is a voltage value between two resistors connected in series.
[0016] As a preferred solution, it also includes a micro-processing unit, which is connected to the output end of the divided voltage value.
[0017] As a preferred solution, a plurality of TVSs are connected in series, and the first resistor is connected to an anode of any TVS.
[0018] Compared with the prior art, the utility model has the following beneficial effects:
[0019] The utility model proposes a TVS state acquisition circuit, introduces a transistor, utilizes the switching characteristics of the transistor and the principle of resistor voltage division, and designs a TVS state acquisition circuit. The non-conducting state and the conducting state of the transistor are utilized, and after the transistor is turned on, the collected divided voltage value is different according to the different TVS states, so that the state of the TVS is judged by the collected voltage value, and because the state of the TVS tube can be judged by the divided voltage value, the cooperation of the software algorithm is not required, and the state of the TVS can be accurately judged. BRIEF DESCRIPTION OF THE DRAWINGS
[0020] Figure 1 It is an existing TVS tube state acquisition circuit diagram in the background technology;
[0021] Figure 2 This is a schematic diagram of a TVS state acquisition circuit in Example 1;
[0022] Figure 3 Schematic diagram of TVS state acquisition circuit when the voltage dividing resistor is a plurality of resistors in Example 2;
[0023] Figure 4 Schematic diagram of TVS state acquisition circuit when the voltage dividing resistor is 2 resistors in Example 2;
[0024] Figure 5 This is a TVS diagnostic circuit in Example 3. DETAILED DESCRIPTION
[0025] The present invention is further described in detail below in combination with test examples and specific implementation methods. However, this should not be understood as the scope of the above subject matter of the present invention being limited to the following embodiments, and all technologies realized based on the content of the present invention belong to the scope of the present invention.
[0026] Example 1
[0027] A TVS state acquisition circuit schematic diagram, such as Figure 2As shown, it includes a transistor and a voltage-dividing resistor, the collector of the transistor BJT1 is connected to the anode of the TVS through the second resistor R2, the base of the transistor BJT1 is connected to the anode of the TVS through the first resistor R1, and the cathode of the TVS is connected to the working voltage source Vcc; a voltage-dividing resistor Rf is connected in series between the emitter of the transistor BJT1 and the ground, and a voltage-dividing voltage value Vf is output from the end of the voltage-dividing resistor Rf away from the ground, and the state of the TVS is determined according to the voltage-dividing voltage value.
[0028] In the related art, since TVS has multiple working states and the corresponding divided voltage values Vf are different in different states, the state of TVS can be judged according to the divided voltage value Vf. Since the state of TVS tube can be judged by the divided voltage value, there is no need for the cooperation of software algorithm, the state of TVS can be accurately judged, and there is no need to add additional signal source, which reduces power consumption and simplifies the circuit.
[0029] In one embodiment, the state of the TVS may include a short circuit state, a cut-off state, and a clamping voltage generating state.
[0030] When the TVS is in a short-circuit state, Vcc=V1, V1 is the TVS anode voltage, and it is also the voltage at one end of the first resistor R1 away from the collector of the transistor BJT, and the voltage at one end of the second resistor R2 away from the base of the transistor BJT. At this time, the V1 voltage is greater than the conduction voltage Vbe between the base and emitter of the transistor, which meets the transistor turn-on condition. The transistor is in a saturated conduction state, and the voltage divider resistor Rf outputs a divided voltage value Vf=V1 at the end away from the ground.
[0031] When the TVS is in the cut-off state, since the clamping voltage of the TVS tube is higher than Vcc, V1 is 0V, V1 is less than the turn-on voltage Vbe of the transistor, the transistor is not turned on, and Vf=0.
[0032] When the TVS generates a clamping voltage state, due to the TVS clamping characteristics, the voltage across the TVS is the TVS clamping voltage Vclamp. At this time, V1=Vcc-Vclamp. Similarly, the V1 voltage is greater than the voltage Vbe between the base and emitter of the transistor, satisfying the transistor turn-on condition. The transistor is in a saturated conduction state, but the voltage value of V1 at this time is different from the voltage value of V1 when the TVS is short-circuited, Vf=Vcc-Vclamp.
[0033] Since the voltage divider value Vf corresponding to the TVS in the three working states is different, by collecting the voltage divider value Vf, according to Vf being V1, 0 or Vcc-Vclamp, the state of the TVS can be determined to be a short circuit state, a cut-off state or a TVS clamping voltage state. For example, when Vf= V1, the TVS state is short circuit; when Vf=0, the TVS state is cut-off; when Vf=Vcc-Vclamp, the TVS state is a clamping voltage state. The controller in the BMS circuit can issue control instructions according to the state of the TVS to control the state of the main circuit MOS, such as controlling the MOS to turn off or on.
[0034] Furthermore, since the transistor in this circuit has two states of conduction and non-conduction, whether the voltage V1 of the transistor base is greater than the voltage Vbe between the transistor base and the emitter is the key. The transistor V1 of this embodiment is greater than or equal to the conduction voltage Vbe between the transistor base and the emitter, thereby ensuring that the transistor can be turned on; similarly, the difference Vz after the working voltage Vcc of this embodiment is subtracted from the TVS clamping voltage Vclamp is configured to be greater than or equal to the conduction voltage Vbe between the transistor base and the emitter, thereby ensuring that the transistor can be turned on. When the value of Vbe is 0.7V, V1 and Vz are configured to be greater than 0.7V.
[0035] Example 2
[0036] The difference between the embodiment 2 and the embodiment 1 is that the voltage dividing resistor Rf includes a plurality of resistors connected in series, such as Figure 3 As shown, the resistance values of several voltage-dividing resistors can be adjusted so that the first voltage-dividing value Vf used to judge the TVS state is within a reasonable range, and the value range of Vf is expanded to facilitate data collection through ADC.
[0037] like Figure 3 As shown, when TVS is in short-circuit state, Vf=(Rbf / Rz)V1; when TVS1 is in cut-off state, Vf=0; when TVS generates clamping voltage state, Vf=(Rbf / Rz)*(Vcc-Vclamp), Rz is the sum of the resistance values of several resistors in series, Rbf is the resistance value of the series resistor between the voltage sampling point and the emitter of the transistor, and Vclamp is the clamping voltage of TVS.
[0038] When the voltage divider resistor Rf includes two resistors Rb1 and Rb2 connected in series, the circuit diagram is as follows: Figure 4 As shown, when TVS is short-circuited, Vf=(Rb1 / (Rb1+Rb2))V1; when TVS is in the cut-off state, Vf=0; when TVS generates the clamping voltage state, Vf=(Rb1 / (Rb1+Rb2))*(Vcc-Vclamp).
[0039] The voltage value can be collected from the sampling point through the ADC, and the collected voltage value can be used to determine whether the TVS is in a short-circuit state, a cut-off state, or a clamping voltage state.
[0040] Example 3
[0041] In the specific application scenario of the BMS control freewheeling loop, a TVS diagnostic circuit is as follows Figure 5 The circuit is composed of R1a, R2a, R3a, R4a, and BJT1. Combined with the clamping characteristics of the TVS tube, the output voltage value is collected to determine the state of the TVS tube. Take TVS1 as an example:
[0042] When TVS1 is in a short-circuit state, Vbat=V1. At this time, the voltage of V1 is greater than the transistor Vbe, which meets the transistor turn-on condition. The transistor is in a saturated conduction state, V2=R4 / (R3+R4)*V1. The voltage value is collected through the ADC port of the MCU (microcontroller unit), identified and judged, and the main circuit MOS is cut off through the driver to protect the battery.
[0043] When TVS1 is in the cut-off state, since the clamping voltage of the TVS tube is higher than Vbat, V1 is 0V, which is less than the transistor turn-on voltage Vbe, the transistor is not turned on, and V2=0;
[0044] When the TVS generates a clamping voltage state, due to the TVS clamping characteristics, the voltage across the TVS is the TVS clamping voltage Vclamp. At this time, V1=Vbat-Vclamp. Similarly, the V1 voltage is greater than the transistor Vbe, satisfying the transistor turn-on condition, and the transistor is in a saturated conduction state. However, the voltage value of V3 at this time is different from the V3 voltage value when the TVS tube is short-circuited. Therefore, the voltage collected by the MCU is also inconsistent with the short-circuit state. The ADC collection value can be used to determine whether the TVS tube is in a short-circuit state, a cut-off state, or a clamping voltage state, and the state of the TVS can be diagnosed. This solution does not require the injection of a signal source, and the power consumption is very low. In addition, the voltage collected by the MCU is different for the three common states of the TVS tube. The accuracy and reliability of the TVS tube state detection are higher, and the circuit stability is higher.
[0045] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.
Claims
1. A TVS state acquisition circuit, characterized in that: Including transistors and voltage divider resistors, The base of the transistor is connected to the anode of the TVS through a first resistor, the collector of the transistor is connected to the anode of the TVS through a second resistor, and the cathode end of the TVS has a working voltage; a voltage-dividing resistor is connected in series between the emitter of the transistor and the ground, and a voltage-dividing voltage value is output from one end of the voltage-dividing resistor, and the state of the TVS is determined according to the voltage-dividing voltage value.
2. A TVS state acquisition circuit as claimed in claim 1, characterized in that: The states of the TVS include a short circuit state, a cut-off state, and a state of generating a clamping voltage.
3. A TVS state acquisition circuit as claimed in claim 1, characterized in that: The anode voltage of the TVS is greater than the conduction voltage between the base and emitter of the transistor.
4. A TVS state acquisition circuit as claimed in claim 1, characterized in that: The voltage dividing resistor includes a plurality of resistors connected in series.
5. A TVS state acquisition circuit as claimed in claim 4, characterized in that: The divided voltage value is the voltage value of the sampling point between the divided resistors.
6. A TVS state acquisition circuit as claimed in claim 4, characterized in that: The voltage-dividing resistor includes two resistors connected in series.
7. A TVS state acquisition circuit as claimed in claim 6, characterized in that: The divided voltage value is the voltage value between two resistors connected in series.
8. A TVS state acquisition circuit according to any one of claims 1 to 7, characterized in that: It also includes a micro-processing unit, which is connected to the output end of the divided voltage value.
9. A TVS state acquisition circuit according to any one of claims 1 to 7, characterized in that: The invention comprises a plurality of TVSs connected in series, wherein the first resistor is connected to an anode of any TVS.