A safety gate circuit for single battery

Abstract

The invention discloses a safety gate circuit for a single cell battery, comprising a boost power module, a voltage reference module, a current sampling module and an on-off control module; the boost power module is respectively connected to the input end of the safety gate, the voltage reference module and the on-off control module, and the voltage reference module and the on-off control module in the safety gate are driven to work by a boost power chip; the voltage reference module is simultaneously connected to the boost power module and the on-off control module; the current sampling module is connected to the input end of the safety gate and the on-off control module via a milliohm-level precision resistor; the on-off control module is respectively connected to the input end of the safety gate, the boost power module, the voltage reference module, the current sampling module and the output end of the safety gate; the safety gate circuit has the characteristics of low input voltage, low on-resistance and large output current, is applied to the single cell battery for power supply, and at the same time requires intrinsically safe explosion-proof scenes, and can well exert the discharge performance of the single cell battery.

Description

Technical Field

[0001] The invention belongs to the technical field of intrinsically safe explosion-proofing, and in particular relates to a safety barrier for a single battery, and a circuit design of the safety barrier. Background Art

[0002] Safety barriers are used in systems that require intrinsically safe explosion-proofing. The input end is a non-intrinsically safe circuit, and the output end is an intrinsically safe circuit. The main function of the safety barrier circuit is to limit the voltage and current supplied to the intrinsically safe circuit.

[0003] A single cell is the smallest battery unit that can discharge independently through the positive and negative electrodes. The three characteristics of a single cell power supply are low output voltage, large output current, and low internal resistance. Depending on the manufacturing material and discharge principle, the nominal value of the output voltage of a single cell is usually between 1.2V and 3.7V, such as 1.5V for a manganese zinc battery, 2.2V for a lead acid battery, 1.55V for a silver oxide battery, and 3.7V for a lithium battery. The maximum output current of a single cell is usually above 2A. The internal resistance of a single cell is low, generally within 100mΩ.

[0004] The safety gate with a single cell as the input terminal should have three characteristics at the same time, namely, low input voltage, large output current, and low on-resistance, in order to better match the performance of the single cell and meet the premise of intrinsic safety. The low input voltage is because the output voltage of the single cell itself is only 1.2V to 3.7V. The large output current is to give full play to the load capacity of the single cell. A key function of the safety gate is to limit the output current. However, if the output current is limited too small, although the requirements of intrinsic safety are met, the output power capacity of the battery is sacrificed. The maximum output current should be above 1A. Low on-resistance is an important indicator. When the single cell is discharged, part of the voltage will drop on the safety gate. Only when the internal resistance of the safety gate is low enough can the output end be guaranteed to have enough voltage. The on-resistance should be below 100 mΩ.

[0005] The conventional safety gate circuit does not meet the above three requirements and is not suitable for single cells. Therefore, it is necessary to design a safety gate circuit for single cells. Summary of the invention

[0006] The purpose of the present invention is to provide an explosion-proof safety barrier for a single battery, and to propose a safety barrier circuit with the characteristics of low input voltage, large output current and low on-resistance.

[0007] The technical solution adopted by the present invention to solve the technical problem is: a safety gate circuit for a single cell battery, including a boost power module, a voltage reference module, a current sampling module and an on-off control module;

[0008] The boost power module is connected to the safety gate input terminal, the voltage reference module and the on-off control module respectively, and includes a boost power chip, a boost power peripheral circuit and a boost power voltage and current limiting circuit. The boost power chip is a power chip specially designed for boosting the voltage of a single cell. The boost power chip input is the positive and negative electrodes of the safety gate input terminal, and the output voltage of the boost power chip is higher than the voltage of the single cell, which is used to drive the voltage reference module and the on-off control module in the safety gate to work. The boost power peripheral circuit includes a capacitor at the input terminal, a capacitor at the output terminal and an inductor of the power chip, which are auxiliary devices necessary for the operation of the boost power chip. The boost power voltage and current limiting circuit includes a voltage regulator and a fuse, which are used to limit the current and output voltage of the boost power chip.

[0009] The voltage reference module is connected to the boost power module and the on-off control module at the same time, and includes a voltage reference source chip and a voltage divider resistor; the voltage reference source chip takes power from the boost power module and outputs a DC voltage signal with a precise amplitude and stability; the voltage divider resistor further divides the output of the voltage reference source chip to obtain the reference voltage signal required by the on-off control module;

[0010] The current sampling module is connected to the safety gate input terminal and the on-off control module through a milliohm-level precision resistor;

[0011] The on-off control module is respectively connected to the safety gate input end, the boost power module, the voltage reference module, the current sampling module and the safety gate output end, and includes a comparator chip, a comparator peripheral circuit and a field effect transistor; the comparator chip is powered by the boost power module, and a pair of signal input pins of the comparator chip are respectively connected to the voltage reference module and the current sampling module; the comparator peripheral circuit includes a comparator input current limiting resistor, a comparator output pull-up resistor and a comparator output grounding capacitor, which are auxiliary devices necessary for the operation of the comparator chip.

[0012] In the safety gate circuit for a single cell, the current sampling module is connected between the negative pole of the safety gate input terminal and the on-off control module, or between the positive pole of the safety gate input terminal and the on-off control module.

[0013] Furthermore, the drain-source on-state resistance R of the field effect tube DS As low as milliohm level, it controls the on and off of the negative circuit or the positive circuit: when controlling the on and off of the negative circuit, the field effect tube is an N-channel type; when controlling the on and off of the positive circuit, the field effect tube is a P-channel type.

[0014] Furthermore, the field effect transistor is of N-channel type, the source S is connected to the current sampling module, the gate G is connected to the output of the comparator chip, the drain D is connected to the negative pole of the safety gate output terminal, and the input side and output side of the positive circuit in the on-off control module are directly connected.

[0015] Furthermore, the field effect transistor is of P-channel type, the source S is connected to the positive electrode of the input side of the on-off control module, the gate G is connected to the output of the comparator chip, and the drain D is connected to the positive electrode of the output side of the on-off control module.

[0016] Furthermore, the field effect transistor is of P-channel type, the source S is connected to the current sampling module, the gate G is connected to the comparator chip output, the drain D is connected to the positive output terminal of the safety gate, and the input side and output side of the negative circuit in the on-off control module are directly connected.

[0017] Furthermore, the field effect transistor is of N-channel type, the source S is connected to the negative electrode of the input side of the on-off control module, the gate G is connected to the output of the comparator chip, and the drain D is connected to the negative electrode of the output side of the on-off control module.

[0018] The beneficial effects of the present invention are: when the input end of the safety barrier circuit of the present invention is connected to a single cell, the output end not only meets the intrinsic safety requirements, but also has a strong load-carrying capacity. At the same time, the voltage drop on the safety barrier is small, which can well exert the performance of the single cell. It has the characteristics of low input voltage, low on-resistance and large output current. It is applied to single cell power supply and requires intrinsically safe explosion-proof scenarios, and can well exert the discharge performance of the single cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 is a structural block diagram of a first embodiment of the present invention;

[0020] Figure 2 is a circuit diagram of a first embodiment of the present invention;

[0021] Figure 3 is a circuit diagram of a second embodiment of the present invention;

[0022] Figure 4 is a block diagram of a third embodiment of the present invention;

[0023] Figure 5 is a circuit diagram of a third embodiment of the present invention;

[0024] Figure 6 4 is a circuit diagram of a fourth embodiment of the present invention.

[0025] The reference numerals of the respective figures are: 1—boost power supply module, 2—voltage reference module, 3—current sampling module, 4—on-off control module. DETAILED DESCRIPTION

[0026] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

[0027] Based on the research on the characteristics of single cells, the present invention proposes a safety gate circuit design scheme, which is applied to the scene of single cell power supply and intrinsically safe explosion-proof, and can give full play to the discharge performance of single cells.

[0028] Implementation Plan 1

[0029] A first embodiment of the present invention relates to a safety barrier circuit for a single cell battery, such as Figure 1 As shown, it includes a boost power module 1, a voltage reference module 2, a current sampling module 3, and an on-off control module 4. The boost power module 1 is connected to the safety gate input terminal, the voltage reference module 2, and the on-off control module 4 respectively. The voltage reference module 2 is connected to the boost power module 1 and the on-off control module 4. The current sampling module 3 is connected to the negative pole of the safety gate input terminal and the on-off control module 4. The on-off control module 4 is connected to the safety gate input terminal, the boost power module 1, the voltage reference module 2, the current sampling module 3, and the safety gate output terminal respectively.

[0030] In this embodiment, if Figure 2 As shown, the boost power module 1 includes a boost power chip U1, a boost power peripheral circuit and a boost power voltage and current limiting circuit. The boost power chip U1 is a switching power chip designed for boosting the voltage of a single cell. The chip input is the positive and negative electrodes of the safety gate input terminal. The chip output voltage is higher than the single cell voltage and is used to drive the voltage reference module 2 and the on-off control module 4 in the safety gate to work. The boost power peripheral circuit includes a capacitor C1 at the input terminal of the power chip, a capacitor C2 at the output terminal and an inductor L1, which are auxiliary devices necessary for the operation of the boost power chip. The boost power voltage and current limiting circuit includes a voltage regulator D1 and a fuse F1, which are used to limit the current and output voltage of the boost power chip.

[0031] In this embodiment, the voltage reference module 2 includes a voltage reference source chip U2 and voltage divider resistors R2 and R3. The voltage reference source chip U2 draws power from the boost power module 1 and outputs a DC voltage signal with an accurate and stable amplitude. The voltage divider resistors R2 and R3 further divide the output of the voltage reference source chip U2 to obtain the reference voltage signal V1 required by the on-off control module.

[0032] In this embodiment, the current sampling module 3 includes a milliohm-level precision resistor R1, one end of the resistor R1 is connected to the negative terminal of the safety gate input terminal, and the other end is connected to the on-off control module 4. When an ampere-level current passes through the current sampling module 3, a millivolt-level voltage drop V2 is generated across the resistor R1. The voltage drop V2 and the output current I o Directly proportional.

[0033] In this embodiment, the on-off control module 4 includes a comparator chip U3, a comparator peripheral circuit and a field effect transistor NMOS1. The comparator chip U3 is driven by a boost power module 1, the signal input positive pin is connected to the voltage reference module 2, and the input negative pin is connected to the current sampling module 3. The comparator peripheral circuit includes a comparator input negative pin current limiting resistor R4, a comparator output pull-up resistor R5 and a comparator output grounding capacitor C3, which are auxiliary devices necessary for the operation of the comparator chip U3. The field effect transistor NMOS1 is an N-channel type, with a drain-source on-state resistor R DS As low as milliohm level, the source S is connected to the current sampling module 3, the gate G is connected to the output of the comparator chip U3, and the drain D is connected to the negative terminal of the safety gate output. The input side and the output side of the positive circuit in the on-off control module 4 are directly connected.

[0034] The working principle of the safety barrier circuit of the present invention is further described below based on this embodiment.

[0035] The function of the safety barrier is to limit the voltage and current of the non-intrinsically safe input signal and output an intrinsically safe electrical signal. The input end of this safety barrier circuit is connected to a single battery. The output voltage of the battery is determined by the principle of electrochemical reaction. Even if the battery fails, its maximum open-circuit output voltage will not rise. Therefore, this safety barrier circuit does not need to provide voltage limiting protection for the input signal.

[0036] When a single cell is short-circuited, the transient current may be very large. For example, the short-circuit current of energy storage batteries can usually reach more than one thousand amperes, which is enough to ignite explosive gases. Therefore, this safety barrier circuit must limit the output current of the single cell. When the current I o Less than the designed cut-off current I c When the circuit is turned on, the output voltage is stable. On the contrary, when the safety barrier output current I o Reach and exceed the designed cut-off current I c When the voltage is too low, the circuit is automatically disconnected and the output voltage is pulled down.

[0037] In this embodiment, the current limiting function is achieved by the coordinated operation of various circuit modules, but the output voltage V B The lowest voltage is only 1.2V, which is unable to drive the comparator chip U3, field effect transistor NMOS1 and voltage reference source chip U2 to operate. The boost power module 1 converts the single cell voltage V B Raise to V C , driving the electronic devices in the safety barrier to work, is a necessary condition for realizing the current limiting function of the safety barrier circuit.

[0038] In this embodiment, the current limiting function is implemented as follows: When the safety barrier outputs an ampere-level current I O When the current sampling module 3 generates a millivolt voltage drop V2 across the resistor R1, V2 = IO × R1. In the voltage reference module 2, the voltage across the voltage divider resistor R3 is V1. By properly selecting the voltage reference chip U1 and the voltage divider resistors R2 and R3, the voltage across R3 satisfies V1 = I C × R1. In the on-off control module 4, the comparator chip U3 compares the size of V1 and V2, which can be divided into two cases:

[0039] (1) When the current I O Less than the designed cut-off current I C When V1 is less than V2, the comparator chip U3 outputs a high level, and the source S and drain D of the field effect tube NMOS1 are turned on. The voltage at the output of the safety gate is the voltage of the single battery minus the voltage divided by the safety gate circuit, that is, V O =V B -I O × (R1 + R DS ) .

[0040] (2) When the current I o Reach and exceed the designed cut-off current I C When V1 is greater than V2, the comparator chip U3 outputs a low level, the source S and drain D of the field effect tube NMOS1 are cut off, and the output voltage of the safety gate is pulled down. After the circuit is cut off, the output current I O must be smaller than the cut-off current I C , the field effect tube NMOS1 will be turned on again, and the output current I O The voltage and current at the output of the safety gate are dynamically stable sawtooth waveforms, and the effective value of the output voltage does not exceed the single cell voltage V B , the output current effective value does not exceed the cut-off current I C .

[0041] Implementation Plan 2

[0042] A second embodiment of the present invention is as follows Figure 3 As shown, the difference from the above-mentioned embodiment 1 is that this embodiment controls the on-off of the positive circuit, while the negative circuit is continuously turned on. The design of the boost power module 1, the voltage reference module 2 and the current sampling module 3 is the same as that of the embodiment 1.

[0043] In this embodiment, the on-off control module 4 includes a comparator chip U3, a comparator peripheral circuit, and a field effect transistor PMOS1. The positive pin of the comparator chip U3 signal input is connected to the current sampling module 3, and the negative pin of the input is connected to the voltage reference module 2. The comparator peripheral circuit includes a comparator input positive pin current limiting resistor R4, a comparator output pull-up resistor R5, and a comparator output grounding capacitor C3. The field effect transistor PMOS1 is a P-channel type, and the drain-source on-state resistor RDS As low as milliohm level, the source S is connected to the positive pole of the safety gate input terminal, the gate G is connected to the output of the comparator chip U3, and the drain D is connected to the positive pole of the safety gate output terminal. The input side and output side of the negative circuit in the on-off control module 4 are directly connected.

[0044] Implementation Plan 3

[0045] A third embodiment of the present invention is as follows Figure 4 As shown, different from the above-mentioned embodiment 1, the current sampling module 3 in this embodiment is connected between the positive pole of the safety gate input terminal and the on-off control module 4. The design of the boost power module 1 and the voltage reference module 2 is the same as that of the embodiment 1.

[0046] In this embodiment, if Figure 5 As shown, the current sampling module 3 includes a milliohm-level precision resistor R1 , one end of the resistor R1 is connected to the positive electrode of the safety gate input terminal, and the other end is connected to the on-off control module 4 .

[0047] In this embodiment, the on-off control module 4 includes a comparator chip U3, a comparator peripheral circuit, and a field effect transistor PMOS1. The comparator chip U3 is driven by a boost power module, the signal input positive pin is connected to the current sampling module 3, and the input negative pin is connected to the voltage reference module 2. The comparator peripheral circuit includes a comparator input positive pin current limiting resistor R4, a comparator output pull-up resistor R5, and a comparator output grounding capacitor C3. The field effect transistor PMOS1 is a P-channel type, and the drain-source on-state resistor R DS As low as milliohm level, the source S is connected to the current sampling module 3, the gate G is connected to the output of the comparator chip U3, and the drain D is connected to the positive output terminal of the safety gate. The input side and output side of the negative circuit in the on-off control module 4 are directly connected.

[0048] Implementation Plan 4

[0049] A second embodiment of the present invention is as follows Figure 6 As shown, the difference from the above-mentioned embodiment 3 is that this embodiment controls the on-off of the negative circuit, while the positive circuit is continuously turned on. The design of the boost power module 1, the voltage reference module 2 and the current sampling module 3 is the same as that of the embodiment 3.

[0050] In this embodiment, the on-off control module 4 includes a comparator chip U3, a comparator peripheral circuit, and a field effect transistor NMOS1. The positive pin of the comparator chip U3 signal input is connected to the voltage reference module 2, and the negative pin is connected to the current sampling module 3. The comparator peripheral circuit includes a comparator input negative pin current limiting resistor R4, a comparator output pull-up resistor R5, and a comparator output grounding capacitor C3. The field effect transistor NMOS1 is an N-channel type, and the drain-source on-state resistor R DSAs low as milliohm level, the source S is connected to the negative pole of the safety gate input terminal, the gate G is connected to the output of the comparator chip U3, and the drain D is connected to the negative pole of the safety gate output terminal. The input side and the output side of the positive circuit in the on-off control module 4 are directly connected.

[0051] The safety gate circuit of the present invention has the characteristics of low input voltage, low on-resistance and large output current under the premise of intrinsic safety. The reasons are as follows:

[0052] (a) Intrinsic safety: The safety barrier circuit of the present invention limits the output current of the single battery, and the current at the output end of the safety barrier does not exceed the cut-off current I C For the output of the boost power chip U1 in the safety barrier, a current limiting resistor R1, a voltage regulator tube D1 and a fuse F1 are set to limit the voltage and current.

[0053] (b) Low input voltage: The safety gate circuit of the present invention is designed with a boost power supply module 1 to drive electronic devices such as comparators to work. The safety gate can also operate normally when the input voltage is as low as 1.2V, and is suitable for single cells made of various materials.

[0054] (c) Low on-resistance: The on-resistance of the safety gate circuit of the present invention is R1 + R DS , where R1 is in the milliohm range. By properly selecting the field effect tube model, the on-resistance can be controlled below 50 milliohms.

[0055] (d) Large output current: The on-resistance of the safety gate circuit of the present invention is only tens of milliohms. When the safety gate outputs 1A current, the voltage drop of the safety gate is only tens of millivolts. The output voltage will not be pulled down by the safety gate, so it can withstand a larger output current.

[0056] The above embodiments are only illustrative of the principles and effects of the present invention, as well as some embodiments of its application. For those skilled in the art, several modifications and improvements may be made without departing from the creative concept of the present invention, and all of these belong to the protection scope of the present invention.

Claims

1. A safety gate circuit for a single battery, characterized in that: It comprises a boost power supply module (1), a voltage reference module (2), a current sampling module (3) and an on-off control module (4); The boost power module (1) is respectively connected to the safety gate input terminal and the voltage reference module (2) and the on-off control module (4), and comprises a boost power chip, a boost power peripheral circuit and a boost power voltage and current limiting circuit. The boost power chip input is the positive and negative electrodes of the safety gate input terminal, and the boost power chip output voltage is higher than the single cell voltage, and is used to drive the voltage reference module (2) and the on-off control module (4) in the safety gate to work; The voltage reference module (2) is connected to the boost power module (1) and the on-off control module (4) at the same time, and comprises a voltage reference source chip and a voltage dividing resistor; the voltage reference source chip draws power from the boost power module (1) and outputs a DC voltage signal; the voltage dividing resistor further divides the output of the voltage reference source chip to obtain a reference voltage signal required by the on-off control module (4); The current sampling module (3) is connected to the safety gate input terminal and the on-off control module (4) via a milliohm-level precision resistor; The on-off control module (4) is respectively connected to the safety gate input terminal, the boost power module (1), the voltage reference module (2), the current sampling module (3) and the safety gate output terminal, and comprises a comparator chip, a comparator peripheral circuit and a field effect transistor, wherein the comparator peripheral circuit comprises a comparator input current limiting resistor, a comparator output pull-up resistor and a comparator output grounding capacitor; a pair of signal input pins of the comparator chip are respectively connected to the voltage reference module (2) and the current sampling module (3), and the drain-source on-state resistance R DS As low as milliohm level, control the on / off of negative or positive circuit: When controlling the on / off of the negative electrode circuit, the field effect transistor is an N-channel type; the source electrode S is connected to the current sampling module (3), the gate electrode G is connected to the output of the comparator chip, the drain electrode D is connected to the negative electrode of the safety gate output terminal, and the input side and the output side of the positive electrode circuit in the on / off control module (4) are directly connected; or, the source electrode S is connected to the negative electrode of the input side of the on / off control module (4), the gate electrode G is connected to the output of the comparator chip, and the drain electrode D is connected to the negative electrode of the output side of the on / off control module (4); When controlling the on and off of the positive circuit, the field effect transistor is of a P-channel type; the source S is connected to the positive electrode of the input side of the on and off control module (4), the gate G is connected to the output of the comparator chip, and the drain D is connected to the positive electrode of the output side of the on and off control module (4); or, the source S is connected to the current sampling module (3), the gate G is connected to the output of the comparator chip, the drain D is connected to the positive electrode of the safety gate output terminal, and the input side and output side of the negative circuit in the on and off control module (4) are directly connected.

2. A safety gate circuit for a single battery according to claim 1, characterized in that: The current sampling module (3) is connected between the negative pole of the safety gate input terminal and the on-off control module (4), or between the positive pole of the safety gate input terminal and the on-off control module (4).

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