A bus disconnector and a bus system

Abstract

The bus isolation switch and the bus system are disclosed. The bus isolation switch uses a charge pump circuit to meet the requirement of non-polarity, and controls the working state of two switch units through the cooperation of a voltage protection circuit and a current protection circuit, so as to protect the load device, completely disconnect the link, and realize self-recovery of the link without a master control chip. Through the application, the technical problem of high cost and poor reliability of the bus isolation switch in the related art is solved, and the technical effects of low cost, high reliability and fast protection speed are achieved.

Description

Technical Field

[0001] This invention relates to the field of bus control technology, and in particular to a bus isolation switch and a bus system. Background Technology

[0002] A bus is a technology that combines power supply lines and signal lines into one, as opposed to a four-wire system (two power supply lines and two communication lines), allowing signals and power to share a single bus. It has the advantages of saving construction and cabling costs, and is convenient for on-site construction and subsequent maintenance. It is widely used in fields such as fire protection, instrumentation, sensors, and industrial control.

[0003] In existing bus control technologies, the design of bus isolators or bus disconnect switches typically employs the following approach:

[0004] (1) The circuit achieves non-polarity through a rectifier bridge and disconnects the link through a relay. Software intervention is required in the main control chip to determine whether the load device corresponding to the isolator is short-circuited and to activate the relay. This circuit has the following disadvantages: using a rectifier bridge to achieve non-polarity will result in a large voltage drop and power loss when the load device alarms, which reduces EMC performance in complex circuit environments. Relay activation for protection has the disadvantages of large delay and high power consumption. A main control chip and software control are required to analyze the signal and determine whether the relay is activated, resulting in relatively high R&D and component costs.

[0005] (2) A combination of rectifier bridge and bridge circuit is used to achieve non-polarity, but the implementation cost is high; the protection of load equipment is achieved by link switching through metal-oxide-semiconductor field-effect transistor (MOSFET), which improves the timeliness of protection, but its control is achieved by the main control chip, which increases the cost.

[0006] (3) The use of dual MOSFETs in the top-down form to realize the link switching improves the timeliness of protection and there is no main control chip. However, its protection only protects against current. When the device is in the cross current mode during protection, the MOSFET will generate heat, which makes its reliability low. Moreover, it is polarized, which restricts on-site construction.

[0007] No effective solution has yet been proposed to address the above problems. Summary of the Invention

[0008] This invention provides a bus disconnect switch and a bus system to at least solve the technical problems of high cost and poor reliability of bus disconnect switches in related technologies.

[0009] According to one aspect of the present invention, a bus isolation switch is provided, comprising: two switching units respectively disposed on a first bus and on both sides of a current protection circuit, wherein the two switching units are interconnected; a charge pump circuit respectively connected to the first bus and a second bus, for making the first bus and the second bus non-polar; a voltage protection circuit respectively connected to the first bus, the second bus, the charge pump circuit and the two switching units, for detecting voltage signals of the first bus and the second bus, and generating a first control signal based on the voltage signals of the first bus and the second bus, wherein the first control signal is used to control the two switching units to be in a conducting state or a cut-off state; and the current protection circuit respectively connected to the first bus and the two switching units, for detecting current signals of the first bus, and generating a second control signal based on the current signals, wherein the second control signal is used to control the two switching units to be in a conducting state or a cut-off state.

[0010] Optionally, the two switching units include a first switching unit and a second switching unit, wherein the first switching unit and the second switching unit are both metal-oxide-semiconductor field-effect transistors (MOSFETs), the source and drain of the MOSFET corresponding to the first switching unit are connected in series to the first bus, the source and drain of the MOSFET corresponding to the second switching unit are connected in series to the first bus, and the gate of the MOSFET corresponding to the first switching unit and the gate of the MOSFET corresponding to the second switching unit are connected.

[0011] Optionally, the charge pump circuit includes: a first diode, a second diode, a third diode, a first resistor, a second resistor, a third resistor, a first capacitor, a second capacitor, a first transistor, a second transistor, and a third transistor. The anode of the first diode is connected to a first bus. The cathode of the first diode is connected to a first terminal of the first resistor and the collector of the first transistor. The second terminal of the first resistor is connected to the base of the first transistor. The emitter of the first transistor is connected to the emitter of the third transistor, a first terminal of the second resistor, and a first terminal of the first capacitor. The second terminal of the first capacitor is connected to the second bus. The base of the third transistor is connected to a first terminal of the third resistor. The second terminal of the third resistor is connected to the anode of the second diode. The cathode of the second diode is connected to the collector of the second transistor. The base of the second transistor is connected to a second terminal of the second resistor. The emitter of the second transistor is connected to the second bus. The collector of the third transistor is connected to the anode of the third diode. The cathode of the third diode is connected to a first terminal of the second capacitor. The second terminal of the second capacitor is connected to the first bus.

[0012] Optionally, the current protection circuit includes: a current sampling unit connected to the first bus for detecting the current signal of the first bus; and a current protection unit connected to the first bus, the two switching units, and the current sampling unit respectively for generating a second control signal based on the current signal.

[0013] Optionally, the current sampling unit includes: a fourth resistor, a fifth resistor, a sixth resistor, a third capacitor, a fourth capacitor, a fifth capacitor, and a sixth capacitor. The fourth resistor is connected in series to the first bus. The first terminal of the parallel connection between the fifth resistor and the third capacitor is connected to the current protection unit and the first terminal of the fourth capacitor, respectively. The second terminal of the fourth capacitor is connected to the first bus. The second terminal of the parallel connection between the fifth resistor and the third capacitor is connected to the first bus. The first terminal of the parallel connection between the sixth resistor and the fifth capacitor is connected to the first bus. The second terminal of the parallel connection between the sixth resistor and the fifth capacitor is connected to the current protection unit and the first terminal of the sixth capacitor, respectively. The second terminal of the sixth capacitor is connected to the first bus.

[0014] Optionally, the current protection unit includes a fourth transistor and a fifth transistor, wherein the base of the fourth transistor is connected to the current sampling unit, the collector of the fourth transistor is connected to the line between the two switching units, and the emitter of the fourth transistor is connected to the first bus; the base of the fifth transistor is connected to the current sampling unit, the collector of the fifth transistor is connected to the line between the two switching units, and the emitter of the fifth transistor is connected to the first bus.

[0015] Optionally, the voltage protection circuit includes: a voltage sampling unit connected to the first bus and the second bus, for detecting the voltage signal of the first bus and the voltage signal of the second bus; and a voltage protection unit connected to the charge pump circuit, the second bus, and the two switching units respectively, for generating a first control signal based on the voltage signal of the first bus and the voltage signal of the second bus.

[0016] Optionally, the voltage sampling unit includes a rectifier bridge, wherein a first end of the rectifier bridge is connected to the first bus, a second end of the rectifier bridge is connected to the second bus, and a third and a fourth end of the rectifier bridge are respectively connected to the voltage protection unit.

[0017] Optionally, the voltage protection unit includes: a seventh resistor, an eighth resistor, a ninth resistor, a seventh capacitor, and an optocoupler. The first terminal of the seventh resistor is connected to the voltage sampling unit, and the cathode of the optocoupler is connected to the voltage sampling unit. The second terminal of the seventh resistor is connected to the first terminal of the eighth resistor and the first terminal of the seventh capacitor, respectively. The second terminal of the seventh capacitor is connected to the line between the voltage sampling unit and the cathode of the optocoupler. The second terminal of the eighth resistor is connected to the first terminal of the ninth resistor and the anode of the optocoupler, respectively. The second terminal of the ninth resistor is connected to the line between the voltage sampling unit and the cathode of the optocoupler. The emitter of the optocoupler is connected to two switching units, and the collector of the optocoupler is connected to the second bus and the charge pump circuit, respectively.

[0018] According to another aspect of the present invention, a bus system is also provided, comprising: at least two buses; and a bus isolation switch as described in any one of the preceding embodiments, wherein two switching units of the bus isolation switch are respectively disposed on any one of the buses.

[0019] In this embodiment of the invention, the bus isolation switch includes: two switching units, respectively disposed on a first bus and on both sides of a current protection circuit, wherein the two switching units are interconnected; a charge pump circuit, respectively connected to the first bus and the second bus, for making the first bus and the second bus non-polar; a voltage protection circuit, respectively connected to the first bus, the second bus, the charge pump circuit and the two switching units, for detecting the voltage signal of the first bus and the voltage signal of the second bus, and generating a first control signal based on the voltage signal of the first bus and the voltage signal of the second bus, wherein the first control signal is used to control the two switching units to be in a conducting state or a cut-off state; and a current protection circuit, respectively connected to the first bus and the two switching units, for detecting the current signal of the first bus, and generating a second control signal based on the current signal, wherein the second control signal is used to control the two switching units to be in a conducting state or a cut-off state. In other words, the bus disconnect switch of this invention utilizes a charge pump circuit to achieve the requirement of non-polarity, and controls the working state of the two switching units through the cooperation of voltage protection circuit and current protection circuit. While protecting the load device, it can completely disconnect the link and achieve self-recovery of the link in the absence of a main control chip. This solves the technical problems of high cost and poor reliability of bus disconnect switches in related technologies, and achieves the technical effects of low cost, high reliability and fast protection speed. Attached Figure Description

[0020] The accompanying drawings, which are included to provide a further understanding of the invention and form part of this application, illustrate exemplary embodiments of the invention and, together with their description, serve to explain the invention and do not constitute an undue limitation thereof. In the drawings:

[0021] Figure 1 A schematic diagram of a bus isolation switch provided in an embodiment of the present invention;

[0022] Figure 2 This is a schematic diagram of another bus isolation switch provided in an embodiment of the present invention.

[0023] The above figures include the following reference numerals:

[0024] 11. Switching unit; 12. Charge pump circuit; 13. Voltage protection circuit; 14. Current protection circuit; 15. First bus; 16. Second bus; D1. First diode; D2. Second diode; D3. Third diode; D4. Fourth diode; D5. Fifth diode; D6. Sixth diode; R1. First resistor; R2. Second resistor; R3. Third resistor; R4. Fourth resistor; R5. Fifth resistor; R6. Sixth resistor; R7. Seventh resistor; R8. Eighth resistor; R9. Ninth resistor; R10. Tenth resistor Resistors; R11, eleventh resistor; R12, twelfth resistor; C1, first capacitor; C2, second capacitor; C3, third capacitor; C4, fourth capacitor; C5, fifth capacitor; C6, sixth capacitor; C7, seventh capacitor; C8, eighth capacitor; C9, ninth capacitor; Q1, first transistor; Q2, second transistor; Q3, third transistor; Q4, fourth transistor; Q5, fifth transistor; OC, optocoupler; UR, rectifier bridge; TVS1, first transient voltage suppressor; TVS2, second transient voltage suppressor. Detailed Implementation

[0025] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0026] It should be noted that the terms "first," "second," etc., in the specification, claims, and drawings of this invention are used to distinguish different objects, rather than to limit a specific order.

[0027] For ease of description, some of the nouns or terms appearing in this invention will be described in detail below.

[0028] Non-polarity: This generally means that the two signal lines can be connected alternately at will, and normal communication of the link can be guaranteed whether they are connected in the correct direction or in the opposite direction.

[0029] Bus: Here it specifically refers to the fire protection bus, which is similar to POWERBUS, that is, it supplies power to the load device and communicates with the load device.

[0030] Isolation and protection: When the load device fails or the link is short-circuited, the connection between the load device and the host computer is effectively disconnected.

[0031] According to one aspect of the present invention, a bus isolation switch is provided. Figure 1This is a schematic diagram of a bus isolation switch provided in an embodiment of the present invention, as shown below. Figure 1 As shown, the bus isolation switch includes:

[0032] Two switching units 11 are respectively disposed on the first bus 15 and on both sides of the current protection circuit 14, wherein the two switching units 11 are connected to each other.

[0033] The charge pump circuit 12 is connected to the first bus 15 and the second bus 16 respectively, and is used to make the first bus 15 and the second bus 16 non-polar;

[0034] The voltage protection circuit 13 is connected to the first bus 15, the second bus 16, the charge pump circuit 12, and two switching units respectively. It is used to detect the voltage signal of the first bus 15 and the voltage signal of the second bus 16, and generate a first control signal based on the voltage signal of the first bus 15 and the voltage signal of the second bus 16. The first control signal is used to control the two switching units to be in the on or off state.

[0035] The current protection circuit 14 is connected to the first bus 15 and the two switching units respectively. It is used to detect the current signal of the first bus 15 and generate a second control signal based on the current signal. The second control signal is used to control the two switching units to be in the on or off state.

[0036] It should be noted that the first bus 15 and the second bus 16 have no positive or negative polarity; normal communication can be guaranteed regardless of whether they are connected in the correct or reverse direction. Optionally, both the first bus 15 and the second bus 16 can be two-bus systems, such as a fire alarm two-bus system.

[0037] The aforementioned switching unit 11 has two operating states: on and off. Optionally, the aforementioned switching unit 11 includes, but is not limited to, a MOSFET.

[0038] Furthermore, the two ends of the first bus 15 and the second bus 16 are respectively used to connect the host computer and the load device to form a link. The bus isolation switch can be set on this link to protect the load device.

[0039] In addition, the voltage protection circuit 13 and current protection circuit 14 mentioned above can automatically control the working state of the two switching units in the absence of a main control chip, so as to realize the disconnection of the link and the self-recovery after disconnection, thereby achieving dual protection for the load equipment and improving the timeliness of protection.

[0040] The bus disconnect switch of this invention utilizes a charge pump circuit to achieve the requirement of non-polarity, and controls the working state of two switching units through the cooperation of voltage protection circuit and current protection circuit. While protecting the load device, it can completely disconnect the link and achieve self-recovery of the link in the absence of a main control chip. This solves the technical problems of high cost and poor reliability of bus disconnect switches in related technologies, and achieves the technical effects of low cost, high reliability and fast protection speed.

[0041] It should be noted that, based on the characteristics of two-bus communication, the principle of using a charge pump to drive high-side switching devices is utilized to achieve non-polarity in the original bridge circuit or rectifier bridge without significantly increasing device costs. This also provides a low-impedance energy return path, ensuring the stability of the two-bus operation and improving its anti-interference capability. Furthermore, in response to load device failures or link short circuits, voltage and current sampling protect the load device while completely disconnecting the link, preventing excessive heat generation on the MOSFETs. Moreover, these two sampling methods enable self-recovery without a master control chip, meaning communication can automatically resume once the load device failure disappears.

[0042] Typically, when a load device fails or a link is short-circuited, current protection is triggered first, followed by voltage protection. If only current protection is used, the link switch will have to withstand the heat loss power for a long time. If only voltage protection is used, the host computer will trigger the protection mechanism first. Therefore, this solution adopts a combination of both, with current protection first and voltage protection later, which means that the host computer protection will not be triggered, and the link switch will not have to withstand the power for a long time.

[0043] Figure 2 A schematic diagram of another bus isolation switch provided in an embodiment of the present invention is shown below. Figure 2 As shown, this bus disconnect switch includes not only two switching units 11, a charge pump circuit 12, a voltage protection circuit 13, a current protection circuit 14, a first bus 15, and a second bus 16, but also a tenth resistor R10, an eleventh resistor R11, a twelfth resistor R12, a fourth diode D4, a fifth diode D5, a sixth diode D6, an eighth capacitor C8, a ninth capacitor C9, a first transient voltage suppressor TVS1, and a second transient voltage suppressor TVS2. While providing isolation protection, this bus disconnect switch can also suppress surges occurring on the first bus 15 and the second bus 16, thereby effectively preventing damage to the load equipment and the various electronic components within the bus disconnect switch.

[0044] In an exemplary embodiment, the two switching units include a first switching unit and a second switching unit, wherein the first switching unit and the second switching unit are both metal-oxide-semiconductor field-effect transistors (MOSFETs). The source and drain of the MOSFET corresponding to the first switching unit are connected in series to the first bus 15, and the source and drain of the MOSFET corresponding to the second switching unit are connected in series to the first bus 15. The gate of the MOSFET corresponding to the first switching unit and the gate of the MOSFET corresponding to the second switching unit are connected.

[0045] The aforementioned metal-oxide-semiconductor field-effect transistor is also known as a metal-oxide-semiconductor field-effect transistor. The MOSFETs mentioned above include, but are not limited to, NMOSFETs and PMOSFETs. When both the first and second switching units are MOSFETs, the two switching units are connected by connecting the gates of the corresponding MOSFETs.

[0046] In an exemplary embodiment, the charge pump circuit 12 includes: a first diode D1, a second diode D2, a third diode D3, a first resistor R1, a second resistor R2, a third resistor R3, a first capacitor C1, a second capacitor C2, a first transistor Q1, a second transistor Q2, and a third transistor Q3. The anode of the first diode D1 is connected to the first bus 15; the cathode of the first diode D1 is connected to the first terminal of the first resistor R1 and the collector of the first transistor Q1; the second terminal of the first resistor R1 is connected to the base of the first transistor Q1; and the emitter of the first transistor Q1 is connected to the emitter of the third transistor Q3 and the second resistor R2. The first terminal of the first transistor Q3 is connected to the first terminal of the first capacitor C1. The second terminal of the first capacitor C1 is connected to the second bus 16. The base of the third transistor Q3 is connected to the first terminal of the third resistor R3. The second terminal of the third resistor R3 is connected to the anode of the second diode D2. The cathode of the second diode D2 is connected to the collector of the second transistor Q2. The base of the second transistor Q2 is connected to the second terminal of the second resistor R2. The emitter of the second transistor Q2 is connected to the second bus 16. The collector of the third transistor Q3 is connected to the anode of the third diode D3. The cathode of the third diode D3 is connected to the first terminal of the second capacitor C2. The second terminal of the second capacitor C2 is connected to the first bus 15.

[0047] It should be noted that when the bus isolation switch is connected in the positive direction, that is, the second bus 16 is connected to the high side of the signal and the first bus 15 is connected to the low side of the signal, the charge pump circuit 12 is reverse-cut off by the diode and transistor in it, and the circuit does not work. The second bus 16 charges the two MOSFETs of the link through D5 and the optocoupler OC to conduct the link and realize the communication between the host computer and the load device.

[0048] When the bus isolation switch is reversed, i.e., the first bus 15 is connected to the high side of the signal and the second bus 16 is connected to the low side of the signal, D5 is reverse-cut off and cannot supply power to the MOSFET. Since the two buses follow a protocol, they switch according to the high and low levels of the symbol. At this time, the charge pump circuit 12 starts to work. When the signal is high, the level is charged to C1 through D1 and Q1 via the charge pump circuit 12. When the signal is low, the energy stored in C1 is supplied to C2 through Q3 and D3. The energy of C2 can flow through D4 and optocoupler OC to charge the two MOSFETs of the link, thereby turning on the link and realizing communication between the host computer and the load device.

[0049] In the above embodiments of the present invention, the first bus 15 and the second bus 16 can be polarized by the charge pump circuit 12. Since one line in the entire link must be directly connected and the other line is a low impedance line, the complexity and cost of on-site construction and maintenance are effectively reduced while ensuring line stability and anti-interference.

[0050] In an exemplary embodiment, the current protection circuit 14 includes: a current sampling unit connected to the first bus 15 for detecting the current signal of the first bus 15; and a current protection unit connected to the first bus 15, two switching units and the current sampling unit respectively for generating a second control signal based on the current signal.

[0051] Since the second control signal is used to control the two switching units to be in the on or off state, in the event of a load device failure or a link short circuit, the current protection circuit 14 protects the load device while completely disconnecting the link through the combination of the current sampling unit and the current protection unit, so that there is no large heat generation on the MOSFET. Furthermore, through the current protection circuit 14, self-recovery can be achieved without the main control chip, that is, communication can be restored automatically after the load device failure disappears.

[0052] In an exemplary embodiment, the current sampling unit includes: a fourth resistor R4, a fifth resistor R5, a sixth resistor R6, a third capacitor C3, a fourth capacitor C4, a fifth capacitor C5, and a sixth capacitor C6. The fourth resistor R4 is connected in series to the first bus 15. The first terminal of the parallel connection between the fifth resistor R5 and the third capacitor C3 is connected to the current protection unit and the first terminal of the fourth capacitor C4, respectively. The second terminal of the fourth capacitor C4 is connected to the first bus 15. The second terminal of the parallel connection between the fifth resistor R5 and the third capacitor C3 is also connected to the first bus 15. The first terminal of the parallel connection between the sixth resistor R6 and the fifth capacitor C5 is connected to the first bus 15. The second terminal of the parallel connection between the sixth resistor R6 and the fifth capacitor C5 is connected to the current protection unit and the first terminal of the sixth capacitor C6, respectively. The second terminal of the sixth capacitor C6 is also connected to the first bus 15.

[0053] It should be noted that in the current protection circuit 14, when the current flowing through R4 is too large, a voltage difference will be formed across the resistor, i.e., V = I * R. When V exceeds the Vbe of the transistor, the corresponding transistor will operate, which will limit the current of the link to Ilimit = Vbe / R4. At this time, the device is operating in the transverse current region.

[0054] In the above embodiments of the present invention, the current sampling unit can be used to sample the current signal of the first bus 15.

[0055] In an exemplary embodiment, the current protection unit includes a fourth transistor Q4 and a fifth transistor Q5, wherein the base of the fourth transistor Q4 is connected to the current sampling unit, the collector of the fourth transistor Q4 is connected to the line between the two switching units, and the emitter of the fourth transistor Q4 is connected to the first bus 15; the base of the fifth transistor Q5 is connected to the current sampling unit, the collector of the fifth transistor Q5 is connected to the line between the two switching units, and the emitter of the fifth transistor Q5 is connected to the first bus 15.

[0056] In the above embodiments of the present invention, the current protection unit can quickly generate a second control signal based on the detected current signal, thereby controlling the working state of the two switching units.

[0057] In an exemplary embodiment, the voltage protection circuit 13 includes: a voltage sampling unit connected to a first bus 15 and a second bus 16, for detecting the voltage signal of the first bus 15 and the voltage signal of the second bus 16; and a voltage protection unit connected to the charge pump circuit 12, the second bus 16, and two switching units respectively, for generating a first control signal based on the voltage signal of the first bus 15 and the voltage signal of the second bus 16.

[0058] Since the first control signal is used to control the two switching units to be in the on or off state, in the event of a load device failure or a link short circuit, the voltage protection circuit 13 protects the load device while completely disconnecting the link through the combination of the voltage sampling unit and the voltage protection unit, so that there is no large heat generation on the MOSFET. Furthermore, through the voltage protection circuit 13, self-recovery can be achieved without the main control chip, that is, communication can be restored automatically after the load device failure disappears.

[0059] It should be noted that in the voltage protection circuit 13, the AC signal of the two buses is converted into a DC signal through the rectifier bridge UR. When the DC voltage is large enough, the optocoupler OC is turned on. At this time, energy flows through the optocoupler OC to charge the two MOSFETs of the link to maintain the link conduction. However, when the load device fails or the link is short-circuited, the voltage will drop and the optocoupler OC will gradually turn off. At this time, energy cannot flow through the optocoupler OC to charge the two MOSFETs of the link, so the link is disconnected.

[0060] In an exemplary embodiment, the voltage sampling unit includes a rectifier bridge UR, wherein a first end of the rectifier bridge UR is connected to a first bus 15, a second end of the rectifier bridge UR is connected to a second bus 16, and a third and fourth end of the rectifier bridge UR are respectively connected to a voltage protection unit.

[0061] In the above embodiments of the present invention, the voltage sampling unit can be used to sample the voltage signals corresponding to the first bus 15 and the second bus 16.

[0062] In an exemplary embodiment, the voltage protection unit includes: a seventh resistor R7, an eighth resistor R8, a ninth resistor R9, a seventh capacitor C7, and an optocoupler OC. The first terminal of the seventh resistor R7 is connected to the voltage sampling unit, and the cathode of the optocoupler OC is connected to the voltage sampling unit. The second terminal of the seventh resistor R7 is connected to the first terminal of the eighth resistor R8 and the first terminal of the seventh capacitor C7, respectively. The second terminal of the seventh capacitor C7 is connected to the line between the voltage sampling unit and the cathode of the optocoupler OC. The second terminal of the eighth resistor R8 is connected to the first terminal of the ninth resistor R9 and the anode of the optocoupler OC, respectively. The second terminal of the ninth resistor R9 is connected to the line between the voltage sampling unit and the cathode of the optocoupler OC. The emitter of the optocoupler OC is connected to two switching units, and the collector of the optocoupler OC is connected to a second bus and a charge pump circuit, respectively.

[0063] In the above embodiments of the present invention, the voltage protection unit can quickly generate a first control signal based on the detected voltage signal, thereby controlling the working state of the two switching units.

[0064] In an exemplary embodiment, the bus isolation switch further includes a tenth resistor R10, which is disposed on the line between the voltage protection circuit 13 and the two switching units 11. The first end of the tenth resistor R10 is connected to the gate of the MOSFET corresponding to the first switching unit and the gate of the MOSFET corresponding to the second switching unit, respectively, and the second end of the tenth resistor R10 is connected to the voltage protection circuit 13.

[0065] In an exemplary embodiment, the bus isolation switch further includes a fourth diode D4 and a fifth diode D5, which are respectively disposed on the line between the charge pump circuit 12 and the voltage protection circuit 13 and on the line between the second bus 16 and the voltage protection circuit 13. The anode of the fourth diode D4 is connected to the charge pump circuit 12, and the cathode of the fourth diode D4 is connected to the voltage protection circuit 13. The anode of the fifth diode D5 is connected to the second bus 16, and the cathode of the fifth diode D5 is connected to the voltage protection circuit 13.

[0066] In an exemplary embodiment, the bus isolation switch further includes a transient voltage suppression circuit, which is connected to the first bus 15 and the second bus 16 respectively, for suppressing surges occurring on the first bus 15 and the second bus 16.

[0067] It should be noted that transient voltage suppression circuits are respectively set at both ends of the first bus 15 and the second bus 16. In specific implementation, transient voltage suppression circuits can be set at either end of the first bus 15 and the second bus 16, or transient voltage suppression circuits can be set at both ends of the first bus 15 and the second bus 16.

[0068] In an exemplary embodiment, the transient voltage suppression circuit includes at least one transient voltage suppressor, wherein when there are multiple transient voltage suppressors, one end of the multiple transient voltage suppressors connected in parallel can be connected to the first bus 15, and the other end can be connected to the second bus 16.

[0069] In an exemplary embodiment, the two switching units include a first switching unit and a second switching unit. The bus isolation switch further includes an eighth capacitor C8, wherein the first end of the eighth capacitor C8 is connected to the line between the first switching unit and the current protection circuit 14, and the second end of the eighth capacitor C8 is connected to the line between the first switching unit and the second switching unit.

[0070] In an exemplary embodiment, the two switching units include a first switching unit and a second switching unit. The bus isolation switch further includes a sixth diode D6 and a ninth capacitor C9, wherein the anode of the sixth diode D6 and the first end of the ninth capacitor C9 are respectively connected to the line between the second switching unit and the current protection circuit 14, and the cathode of the sixth diode D6 and the second end of the ninth capacitor C9 are respectively connected to the line between the first switching unit and the second switching unit.

[0071] In an exemplary embodiment, the bus isolation switch further includes an eleventh resistor R11 and a twelfth resistor R12, wherein the eleventh resistor R11 and the twelfth resistor R12 are connected in series, the first end of the eleventh resistor R11 is connected to the first bus 15 and to the second end of the second capacitor C2, the second end of the eleventh resistor R11 is connected to the first end of the twelfth resistor R12, and the second end of the twelfth resistor R12 is connected to the first bus 15, specifically, the second end of the twelfth resistor R12 is connected to the first bus 15 between the voltage protection circuit 13 and the second switching unit.

[0072] In summary, in this embodiment of the invention, a non-polar bus isolation switch is constructed by utilizing the inherent characteristics of two-bus communication, the working principle of a charge pump, a simple current and voltage protection circuit, and conventional MOSFET devices, and has the following characteristics:

[0073] The principle is simple: it achieves non-polarity by utilizing the principle of a charge pump, and improves the timeliness of protection by using the simplest current protection circuit and voltage protection circuit together;

[0074] Low cost: The main components of this solution are transistors, optocouplers, MOS transistors, and resistors, all of which are very common electronic components on the market;

[0075] High reliability: The link in this embodiment of the invention is non-polar, and there is no path in one direction that is blocked. Therefore, its anti-interference ability and surge resistance are greatly improved. Due to its low link impedance, it has high reliability in long-distance field applications.

[0076] Fast protection speed: Actual tests have shown that the current protection of this solution can respond within 100us and the voltage protection within 60ms.

[0077] According to another aspect of the present invention, a bus system is also provided, comprising: at least two buses; and a bus isolation switch as described above, wherein the two switching units of the bus isolation switch are respectively disposed on one of the buses.

[0078] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention.

Claims

1. A bus disconnect switch, characterized in that, include: Two switching units are respectively disposed on the first bus and on both sides of the current protection circuit, wherein the two switching units are connected in series with each other; A charge pump circuit is connected to the first bus and the second bus respectively, and is used to make the first bus and the second bus non-polar; A voltage protection circuit is connected to the first bus, the second bus, the charge pump circuit, and the two switching units respectively. It is used to detect the voltage signal of the first bus and the voltage signal of the second bus, and generate a first control signal based on the voltage signal of the first bus and the voltage signal of the second bus. The first control signal is used to control the two switching units to be in the on or off state. The current protection circuit is connected to the first bus and the two switching units respectively, and is used to detect the current signal of the first bus and generate a second control signal based on the current signal. The second control signal is used to control the two switching units to be in a conducting state or a cut-off state. The charge pump circuit includes: a first diode, a second diode, a third diode, a first resistor, a second resistor, a third resistor, a first capacitor, a second capacitor, a first transistor, a second transistor, and a third transistor. The anode of the first diode is connected to a first bus. The cathode of the first diode is connected to the first terminal of the first resistor and the collector of the first transistor. The second terminal of the first resistor is connected to the base of the first transistor. The emitter of the first transistor is connected to the emitter of the third transistor, the first terminal of the second resistor, and the first terminal of the first capacitor. The second terminal of the first capacitor is connected to the second bus. The base of the third transistor is connected to the first terminal of the third resistor. The second terminal of the third resistor is connected to the anode of the second diode. The cathode of the second diode is connected to the collector of the second transistor. The base of the second transistor is connected to the second terminal of the second resistor. The emitter of the second transistor is connected to the second bus. The collector of the third transistor is connected to the anode of the third diode. The cathode of the third diode is connected to the first terminal of the second capacitor. The second terminal of the second capacitor is connected to the first bus.

2. The bus disconnect switch according to claim 1, characterized in that, The two switching units include a first switching unit and a second switching unit, wherein the first switching unit and the second switching unit are both metal-oxide-semiconductor field-effect transistors (MOSFETs). The source and drain of the MOSFET corresponding to the first switching unit are connected in series to the first bus, and the source and drain of the MOSFET corresponding to the second switching unit are connected in series to the first bus. The gate of the MOSFET corresponding to the first switching unit and the gate of the MOSFET corresponding to the second switching unit are connected.

3. The bus disconnect switch according to claim 1, characterized in that, The current protection circuit includes: A current sampling unit, connected to the first bus, is used to detect the current signal of the first bus; The current protection unit is connected to the first bus, the two switching units, and the current sampling unit, respectively, and is used to generate a second control signal based on the current signal.

4. The bus disconnect switch according to claim 3, characterized in that, The current sampling unit includes: a fourth resistor, a fifth resistor, a sixth resistor, a third capacitor, a fourth capacitor, a fifth capacitor, and a sixth capacitor. The fourth resistor is connected in series to the first bus. The first terminal of the parallel connection between the fifth resistor and the third capacitor is connected to the current protection unit and the first terminal of the fourth capacitor, respectively. The second terminal of the fourth capacitor is connected to the first bus. The second terminal of the parallel connection between the fifth resistor and the third capacitor is also connected to the first bus. The first terminal of the parallel connection between the sixth resistor and the fifth capacitor is connected to the first bus. The second terminal of the parallel connection between the sixth resistor and the fifth capacitor is connected to the current protection unit and the first terminal of the sixth capacitor, respectively. The second terminal of the sixth capacitor is connected to the first bus.

5. The bus disconnect switch according to claim 3, characterized in that, The current protection unit includes a fourth transistor and a fifth transistor, wherein the base of the fourth transistor is connected to the current sampling unit, the collector of the fourth transistor is connected to the line between the two switching units, and the emitter of the fourth transistor is connected to the first bus; the base of the fifth transistor is connected to the current sampling unit, the collector of the fifth transistor is connected to the line between the two switching units, and the emitter of the fifth transistor is connected to the first bus.

6. The bus disconnect switch according to claim 1, characterized in that, The voltage protection circuit includes: A voltage sampling unit, connected to the first bus and the second bus, is used to detect the voltage signal of the first bus and the voltage signal of the second bus; A voltage protection unit is connected to the charge pump circuit, the second bus, and the two switching units respectively, and is used to generate a first control signal based on the voltage signal of the first bus and the voltage signal of the second bus.

7. The bus disconnect switch according to claim 6, characterized in that, The voltage sampling unit includes a rectifier bridge, wherein a first end of the rectifier bridge is connected to the first bus, a second end of the rectifier bridge is connected to the second bus, and a third and a fourth end of the rectifier bridge are respectively connected to the voltage protection unit.

8. The bus disconnect switch according to claim 6, characterized in that, The voltage protection unit includes a seventh resistor, an eighth resistor, a ninth resistor, a seventh capacitor, and an optocoupler. The first terminal of the seventh resistor is connected to the voltage sampling unit, and the cathode of the optocoupler is connected to the voltage sampling unit. The second terminal of the seventh resistor is connected to the first terminal of the eighth resistor and the first terminal of the seventh capacitor, respectively. The second terminal of the seventh capacitor is connected to the line between the voltage sampling unit and the cathode of the optocoupler. The second terminal of the eighth resistor is connected to the first terminal of the ninth resistor and the anode of the optocoupler, respectively. The second terminal of the ninth resistor is connected to the line between the voltage sampling unit and the cathode of the optocoupler. The emitter of the optocoupler is connected to two switching units, and the collector of the optocoupler is connected to the second bus and the charge pump circuit, respectively.

9. A bus system, characterized in that, include: At least two buses; The bus disconnect switch as described in any one of claims 1 to 8, wherein the two switching units of the bus disconnect switch are respectively disposed on any one of the buses.

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