CN206894232U - Non-isolated CAN overvoltage crowbar - Google Patents

Abstract

The utility model discloses a kind of non-isolated CAN overvoltage crowbar; including CAN transceiver and connected high-low position bus signal line; also include matching and the filter circuit being connected between the CAN transceiver and high-low position bus signal line, for the impedance matching between each node and the electromagnetic interference of filtering common mode；And overvoltage crowbar, at least it is used to be compared with reference voltage after bus common mode voltage sample, and according to comparison result cut-out or the bus signal transmission between self- recoverage CAN transceiver and high-low position bus signal line.The utility model realizes the non-isolated overvoltage protection to CAN transceiver and subsequent conditioning circuit; eliminate the cost of isolation element; realize the CAN overvoltage protection scheme of low cost; installing space needed for isolation element etc. is saved simultaneously; the difficulty of PCB and product layout is reduced, is advantageous to reduce the volume of product.

Description

Non-isolated CAN overvoltage crowbar

Technical field

A kind of CAN overvoltage crowbar is the utility model is related to, especially a kind of non-isolated CAN overvoltage protection Circuit.

Background technology

CAN is Controller Area Network abbreviation（Hereinafter referred to as CAN）, be ISO International standardizations string Row communication protocol.It is various each for the requirement to security, comfortableness, convenience, low nuisanceless, low cost in automobile industry The electronic control system of sample is developed.Due to the data type used in being communicated between these systems and reliability is wanted Ask and be not quite similar, situation about being made up of multiple bus is a lot, and the quantity of wire harness is consequently increased.

For adaptation " quantity for reducing wire harness ", the needs of " by multiple LAN, carrying out the high-speed communication of mass data ", face It is developed to the CAN communication protocols of automobile, hereafter, CAN is standardized by ISO11898 and ISO11519, Europe has been the standard agreement of automotive networking.

CAN is widely used in automobile and manufactureing automation LAN, it is realized with its high-performance and high reliability Real-time between each node of dcs, reliable data communication.

For improving the reliability of CAN node, most common method is exactly to use isolated transceiver by bus Electrical isolation is carried out with control circuit, high pressure interference is obstructed outside control system, effectively Guarantee control system and the person Safety.Moreover, electrical isolation can also effectively prevent from forming ground loop, suppress to be caused by ground potential differences, ground loop Various common mode disturbances, and common-mode voltage is all born by isolation strip, ensures bus in severe jamming and other system-level noises In the presence of uninterrupted, zero defect operation.

But it is galvanically isolated while CAN reliability is improved, also brings being significantly increased for order circuit cost, Either traditional Phototube Coupling or more advanced Magnetic isolation, are not always the case, so for some low costs but needing For the application of high reliability, isolation scheme does not apply to simultaneously.

In addition, in order to meet the insulating requirements of isolation voltage, need to ensure in PCB and product layout it is certain climb electricity away from From and the air gap, this further means that the increase of small product size.

Utility model content

The purpose of this utility model is exactly in order to solve the above-mentioned problems in the prior art, inexpensive non-isolated Some overvoltage crowbars are added on the basis of CAN structure, for most common high pressure interference on CAN signal and System noise has carried out going comprehensive suppression and protection, avoids control system and bus transceiver because disturbing or impacting by pressing dry And cause communicating interrupt even hardware damage, substantially increase the reliability of CAN communication.

The purpose of this utility model is achieved through the following technical solutions：

Non-isolated CAN overvoltage crowbar, including CAN transceiver and connected high-low position bus letter Number line, in addition to be connected between the CAN transceiver and high-low position bus signal line

Matching and filter circuit, for the impedance matching between each node and the electromagnetic interference of filtering common mode；

And overvoltage crowbar, at least it is used to be compared with reference voltage after bus common mode voltage sample, and root According to comparison result cut-out or the bus signal transmission between self- recoverage CAN transceiver and high-low position bus signal line.

Preferably, described non-isolated CAN overvoltage crowbar, wherein：The matching and filter circuit are included altogether Mould inductance, the first build-out resistor and the second build-out resistor, 2 pin of the common mode inductance connect high-order bus signal line, and its 1 pin meets institute One end of overvoltage crowbar and the first build-out resistor is stated, the other end of first build-out resistor passes through capacity earth；It is described 3 pin of common mode inductance connect lower bus signal wire, and its 4 pin meets one end of the overvoltage crowbar and the second build-out resistor, institute The other end for stating the second build-out resistor passes through the capacity earth.

Preferably, described non-isolated CAN overvoltage crowbar, wherein：The overvoltage crowbar includes two level Protection circuit, the safe secondary protection circuit include

Over-voltage detection circuit, for will be compared after bus common mode voltage sample with reference voltage and export high or low electricity It is flat；

And over-pressed breaking circuit, for the low or high level cut-out exported according to the over-voltage detection circuit or self- recoverage Bus signal transmission between CAN transceiver and high-low position bus signal line.

Preferably, described non-isolated CAN overvoltage crowbar, wherein：The over-voltage detection circuit includes first Diode, the second diode, the first sampling resistor, the second sampling resistor, comparator and reference voltage, first diode and The anode of second diode connects 1 pin and 4 pin of the common mode inductance respectively, and their negative electrode passes through the first sampling of series connection respectively Resistance and the second sampling resistor ground connection, the connection termination of first sampling resistor and the second sampling resistor are described more anti-than machine To input, the positive input of the comparator connects the reference voltage, and the output end of the comparator meets 5V by resistance Power end and high or low level signal is exported to the over-pressed breaking circuit.

Preferably, described non-isolated CAN overvoltage crowbar, wherein：The output end than machine is also connected with Processor, and it is sent to over voltage alarm signal.

Preferably, described non-isolated CAN overvoltage crowbar, wherein：The over-pressed breaking circuit includes first Metal-oxide-semiconductor, the second metal-oxide-semiconductor, first grid resistance, second grid resistance, the first voltage-regulator diode and the second voltage-stabiliser tube, described first The drain electrode of metal-oxide-semiconductor and the second metal-oxide-semiconductor connects 1 pin and 4 pin of the common mode inductance respectively, and it is total that their source electrode meets the CAN respectively The CANH pins and CANL pins of line transceiver, their grid meet the one of first grid resistance and second grid resistance respectively End, the other end of the first grid resistance and second grid resistance are all connected with the output end of the comparator, and described first First voltage-regulator diode is connected between the source electrode and grid of metal-oxide-semiconductor, between the source electrode and grid of second metal-oxide-semiconductor respectively Connect second voltage-regulator diode.

Preferably, described non-isolated CAN overvoltage crowbar, wherein：First metal-oxide-semiconductor and the second metal-oxide-semiconductor It is that small-power N links up metal-oxide-semiconductor.

Preferably, described non-isolated CAN overvoltage crowbar, wherein：The overvoltage crowbar also includes one Level absorbing circuit, the first order absorption circuit include two by bus common mode voltage clamping in the TVS pipe clamper electricity of setting voltage Road, each TVS pipe clamp circuit include TVS pipe, RC parallel circuits, the termination common mode electricity of a TVS pipe 1 pin of sense, 4 pin of a termination common mode inductance of another TVS pipe, their other end access reference after concatenating RC parallel circuits Ground.

Preferably, described non-isolated CAN overvoltage crowbar, wherein：The clamp voltage of the TVS pipe is less than institute State maximum tolerance bus level of the reference voltage less than the CAN transceiver.

Preferably, described non-isolated CAN overvoltage crowbar, wherein：The non-isolated CAN overvoltage protection Circuit is at least applied to the CAN communication module of low-pressure electric automotive motor controller.

The advantages of technical solutions of the utility model, is mainly reflected in：

The utility model deft design, circuit is simple, and the impedance matching between each node is carried out by matching and filter circuit And the electromagnetic interference of filtering common mode, with reference to two level overvoltage crowbar, when there is over-pressed for a long time or big energy impact in bus, CAN transceiver is disconnected from bus, avoids its damage, send two pairs of subsequent control circuits to protect, without using CAN Bus electrical isolation（Phototube Coupling or Magnetic isolation）Scheme, realize to the non-isolated of CAN transceiver and subsequent conditioning circuit Overvoltage protection, eliminate the cost of isolation element, realize low cost CAN overvoltage protection scheme, while save every From installing space needed for element etc., the difficulty of PCB and product layout is reduced, is advantageous to reduce the volume of product.

The utility model further combined with first order absorption circuit, for moment small energy impact have response speed quickly and Certain absorbability, two-stage protection against excessive pressure, for moment small energy impact and for a long time, big energy overvoltage provides respectively Have and targetedly absorb and protection circuit, more fully and effectively, reliability more preferably, and all has self- recoverage work(for protection Can, there is certain adaptivity.

By to the preferred of the first metal-oxide-semiconductor and the second metal-oxide-semiconductor, reducing the decay for being advantageous to bus signals.

Brief description of the drawings

Fig. 1 is structural representation of the present utility model；

Fig. 2 is circuit diagram of the present utility model.

Embodiment

The purpose of this utility model, advantage and feature, figure will be carried out by the non-limitative illustration of preferred embodiment below Show and explain.These embodiments are only the prominent examples using technical solutions of the utility model, all to take equivalent substitution or wait Effect conversion and formed technical scheme, all fall within the requires of the utility model protection within the scope of.

The utility model discloses non-isolated CAN overvoltage crowbar, at least applied to low-pressure electric electric motor of automobile The CAN communication module of controller, as shown in accompanying drawing 1, accompanying drawing 2, the non-isolated CAN overvoltage crowbar includes CAN transceiver U2 and connected high-order bus signal line CAN_H, lower bus signal wire CAN_L, the CAN are total Line transceiver U2 VCC pin meets 5V power end+5V, and its VREF pin is sky, and its RXD pin and TXD pins connect control terminal CAN_RXD ends and CAN_TXD ends, its GND pin and S pins ground connection, its CAN pin and CANL pins and high-low position bus letter Number it is also associated between line CAN_H, CAN_L

Matching and filter circuit 1, for the impedance matching between each node and the electromagnetic interference of filtering common mode；

And overvoltage crowbar 2, at least it is used to be compared with reference voltage after bus common mode voltage sample, and According to total between comparison result cut-out or self- recoverage CAN transceiver U2 and high-low position bus signal line CAN_H, CAN_L Line signal transmits.Wherein, the bus common mode voltage refer to high-order bus signal line CAN_H ends relative to the voltage of reference ground with And lower bus signal wire CAN_L ends are relative to the voltage of reference ground, and bus differential mode voltage refers to high-order bus signal line CAN_H ends relative to lower bus signal wire CAN_L ends pressure difference.

Specifically, as shown in Figure 2, the matching and filter circuit 1 include the common mode inductance near egress bus L1, the first build-out resistor R3 and the second build-out resistor R4, the common mode inductance L1 are used for the electromagnetic interference signal for filtering common mode, and And electromagnetic radiation caused by suppressing high speed signal is outwards launched, the first build-out resistor R3 and the second build-out resistor R4 are used for respectively Impedance matching between node, 2 pin of the common mode inductance L1 meet high-order bus signal line CAN_H, and its 1 pin connects the overvoltage protection The build-out resistor R3 of circuit 2 and first one end, the other end of the first build-out resistor R3 are grounded by electric capacity C3；The common mode Inductance L1 3 pin meet lower bus signal wire CAN_L, and its 4 pin meets the one of the build-out resistor R4 of overvoltage crowbar 2 and second End, the other end of second build-out resistor are grounded by the electric capacity C3.

As shown in accompanying drawing 1, accompanying drawing 2, the overvoltage crowbar 2 includes first order absorption circuit 22, the first order absorption electricity Road 22 is used to bus common mode voltage clamping setting voltage, and it includes two by bus common mode voltage clamping in setting voltage TVS pipe clamp circuit, each TVS pipe clamp circuit include a TVS pipe and RC parallel circuits, one end of the TVS pipe D1 1 pin of the common mode inductance L1 is connect, the other end of the TVS pipe D1 concatenates the RC parallel circuits being made up of resistance R1 and electric capacity C1 After access reference ground, a termination common mode inductance L1 of the TVS pipe D2 4 pin, the other end of the TVS pipe D2 is concatenated by resistance Reference ground is accessed after the RC parallel circuits that R2 and electric capacity C2 is formed.

The clamp voltage of wherein described TVS pipe D1, D2 should be more lower slightly than the withstanding voltage of bus transceiver, if for example, The highest bus voltage that bus transceiver can bear is 15V, then should select TVS pipe of the clamp voltage for 12V or so, so as to have Effect protection bus transceiver.

Why the first order absorption circuit is set, be because CAN level state be divided into it is dominant and recessive, wherein aobvious CAN_H=3.5V, CAN_L=1.5V during property level；CAN_H=CAN_L=2.5V during recessive level, so common CAN letter Number common-mode voltage should be no more than 5V, although the bus level that the CAN transceiver of main flow is resistant to will be than much higher, most Low can also bear 12V, and highest even arrives 40V, wherein the maximum tolerance bus level of the CAN transceiver refers to CAN The maximum bus common mode voltage that bus transceiver can bear, i.e. the CANH pins of CAN transceiver and CANL pins institute energy The maximum voltage born.

But due to high voltage transient spike impact be present, it is therefore desirable to make full use of TVS pipe that there is the response speed that is exceedingly fast Degree（Subnanosecond level）This feature, when bus common mode voltage is higher than the clamp voltage of TVS pipe, it will can surpass at a terrific speed Partially absorbing for clamp voltage is crossed, and voltage is just clamped down on clamp voltage, so as to play protection CAN transceiver With the effect of rear end control circuit.

Suppress to make well although the first order absorption circuit has the moment small energy impact occurred in bus and interference With, but the overvoltage of the long-time for occurring in bus or big energy impact now just need another but without too big effect Outer circuit is protected, and the corresponding overvoltage crowbar 2 also includes safe secondary protection circuit 21.

Specifically, as shown in accompanying drawing 1, accompanying drawing 2, the safe secondary protection circuit includes 21

Over-voltage detection circuit 211, for will be compared and export with reference voltage after bus common mode voltage sample it is high or Low level；

And over-pressed breaking circuit 212, the low or high level for being exported according to the over-voltage detection circuit 211 is cut off or oneself Recover the bus signal transmission between CAN transceiver U2 and high-low position bus signal line CAN_H, low CAN_L.

The over-voltage detection circuit 211 includes the first diode D3, the second diode D4, the first sampling resistor R5, second Sampling resistor R6, comparator U1 and reference voltage, the first diode D3 and the second diode D4 anode connect described respectively Common mode inductance L1 1 pin and 4 pin, their negative electrode are connect by the first sampling resistor R5 and the second sampling resistor R6 of series connection respectively Ground, the connection of first sampling resistor and the second sampling resistor terminate the reverse input end than machine U1, the comparison Device U1 positive input connects the reference voltage, and the reference voltage can be configured according to being actually needed, such as 2V, 3.3V, 5V etc., the output end of the comparator U1 5V power end+5V are connect by resistance R9 and export high or low level signal to The over-pressed breaking circuit 212, and the output end than machine U1 is also connected with processor, and it is sent to over voltage alarm letter Number.

Wherein, the first diode D3 and the second diode D4 introduces bus common mode voltage by the first sampling resistor R5 With the sample circuit of the second sampling resistor R6 compositions, one voltage signal of production is conveyed to the comparator U1, the comparator U1 With reference voltage set in advance carry out voltage ratio compared with.

Resistance by changing sampling resistor R5 and R6 can adjust the threshold voltage of bus overvoltage shut-off, this general limit Value is more slightly higher than the clamp voltage of TVS pipe in overpressure absorbing circuit, but less than the maximum tolerance bus of the CAN transceiver Level.

When bus common mode voltage is in rated range, i.e., less than reference voltage when, comparator U1 output is high electricity It is flat；But if bus voltage exceed setting threshold voltage, i.e., more than reference voltage when, the comparator U1 will export low electricity Flat BUS OFF signal gives over-pressed breaking circuit, and produces bus over voltage alarm signal simultaneously and make corresponding software to processor Processing.

Further, the over-pressed breaking circuit 212 include the first metal-oxide-semiconductor Q1, the second metal-oxide-semiconductor Q2, first grid resistance R7, Second grid resistance R8, the first voltage-regulator diode D5 and the second voltage-stabiliser tube D6's, the first metal-oxide-semiconductor Q1 and the second metal-oxide-semiconductor Q2 Drain electrode connects 1 pin and 4 pin of the common mode inductance respectively, and the CANH that their source electrode meets the CAN transceiver U2 respectively draws Pin and CANL pins, their grid connect first grid resistance R7 and second grid resistance R8 one end, the first grid respectively Electrode resistance R7 and second grid resistance the R8 other end are all connected with the output end of the comparator U1, and the first metal-oxide-semiconductor Q1 Source electrode and grid between connect the first voltage-regulator diode D5, between the source electrode and grid of the second metal-oxide-semiconductor Q2 respectively Connect the second voltage-regulator diode D6.

The first metal-oxide-semiconductor Q1, the second metal-oxide-semiconductor Q2 are switched using small-power N-channel MOS pipe as bus signal transmission, So, when opening, the first metal-oxide-semiconductor Q1, the second metal-oxide-semiconductor Q2 is allowed to be operated in non-fully conducting state, that is, grid source electrode Voltage Vgs is slightly lower, and drain current Id also can be a little bit smaller, so that gate-source voltage Vds at most only has several volts of zero point Pressure drop, ensures the decay very little of bus signals, and first grid resistance R7 and second grid the resistance R8 is used to limit the first MOS Pipe Q1, the second metal-oxide-semiconductor Q2 grid current, the first voltage-regulator diode D5 and the second voltage-regulator diode D6 are used to limit first Metal-oxide-semiconductor Q1, the second metal-oxide-semiconductor Q2 gate-source voltage.

When CAN level occurs over-pressed for a long time, the over-voltage detection circuit 211 exports low level, now described First metal-oxide-semiconductor Q1, the second metal-oxide-semiconductor Q2 are turned off, so as to cut off the CAN transceiver U2 and high-low position bus signals Bus signal transmission between line CAN_H, CAN_L, the CAN transceiver of the node break from CAN structure, avoided By overvoltage impact in bus, until the over-voltage detection circuit 211 detection bus common mode voltage is turned again in rated range, When being less than reference voltage, the comparator output is high level, and the first metal-oxide-semiconductor Q1, the second metal-oxide-semiconductor Q2 are open-minded again, Bus signal transmission between described CAN transceiver U2 and high-low position bus signal line CAN_H, CAN_L is recovered normal and passed It is defeated.

The utility model still has numerous embodiments, all technologies formed using equivalents or equivalent transformation Scheme, all fall within the scope of protection of the utility model.

Claims (10)

1. non-isolated CAN overvoltage crowbar, including CAN transceiver（U2）And connected high-low position bus Signal wire（CAN_H、CAN_L）, it is characterised in that：Also include being connected to the CAN transceiver（U2）With high-low position bus Signal wire（CAN_H、CAN_L）Between

Matching and filter circuit（1）, for the impedance matching between each node and the electromagnetic interference of filtering common mode；

And overvoltage crowbar（2）, at least it is used to be compared with reference voltage after bus common mode voltage sample, and root According to comparison result cut-out or self- recoverage CAN transceiver（U2）With high-low position bus signal line（CAN_H、CAN_L）Between Bus signal transmission.

2. non-isolated CAN overvoltage crowbar according to claim 1, it is characterised in that：The matching and filtering Circuit（1）Including common mode inductance（L1）, the first build-out resistor（R3）With the second build-out resistor（R4）, the common mode inductance（L1）'s 2 pin connect high-order bus signal line（CAN_H）, its 1 pin connects the overvoltage crowbar（2）And first build-out resistor（R3）One End, first build-out resistor（R3）The other end pass through electric capacity（C3）Ground connection；The common mode inductance（L1）3 pin to connect low level total Line signal wire（CAN_L）, its 4 pin connects the overvoltage crowbar（2）And second build-out resistor（R4）One end, described second With resistance（R4）The other end pass through the electric capacity（C3）Ground connection.

3. non-isolated CAN overvoltage crowbar according to claim 2, it is characterised in that：The overvoltage protection electricity Road（2）Including safe secondary protection circuit（21）, the safe secondary protection circuit（21）Including

Over-voltage detection circuit（211）, for will be compared and export high or low with reference voltage after bus common mode voltage sample Level；

And over-pressed breaking circuit（212）, for according to the over-voltage detection circuit（211）The low or high level of output is cut off or oneself Recover CAN transceiver（U2）With high-low position bus signal line（CAN_H、CAN_L）Between bus signal transmission.

4. non-isolated CAN overvoltage crowbar according to claim 3, it is characterised in that：The overvoltage detection electricity Road（211）Including the first diode（D3）, the second diode（D4）, the first sampling resistor（R5）, the second sampling resistor（R6）, ratio Compared with device（U1）And reference voltage, first diode（D3）With the second diode（D4）Anode connect the common mode inductance respectively （L1）1 pin and 4 pin, their negative electrode passes through the first sampling resistor of series connection respectively（R5）And second sampling resistor（R6）Connect Ground, first sampling resistor（R5）With the second sampling resistor（R6）Connection terminate the comparator（U1）Reverse input End, the comparator（U1）Positive input connect the reference voltage, the comparator（U1）Output end pass through resistance （R9）Connect 5V power ends（+5V）And high or low level signal is exported to the over-pressed breaking circuit（212）.

5. non-isolated CAN overvoltage crowbar according to claim 4, it is characterised in that：The comparator（U1） Output end be also connected with processor, and be sent to over voltage alarm signal.

6. non-isolated CAN overvoltage crowbar according to claim 4, it is characterised in that：The overvoltage shut-off electricity Road（212）Including the first metal-oxide-semiconductor（Q1）, the second metal-oxide-semiconductor（Q2）, first grid resistance（R7）, second grid resistance（R8）, first Voltage-regulator diode（D5）And second voltage-stabiliser tube（D6）, first metal-oxide-semiconductor（Q1）With the second metal-oxide-semiconductor（Q2）Drain electrode meet institute respectively 1 pin and 4 pin of common mode inductance are stated, their source electrode connects the CAN transceiver respectively（U2）CANH pins and CANL draw Pin, their grid connect first grid resistance respectively（R7）And second grid resistance（R8）One end, the first grid resistance （R7）With second grid resistance（R8）The other end be all connected with the comparator（U1）Output end, and first metal-oxide-semiconductor （Q1）Source electrode and grid between connect first voltage-regulator diode（D5）, the source electrode and grid of the second metal-oxide-semiconductor Q2 it Between connect second voltage-regulator diode respectively（D6）.

7. non-isolated CAN overvoltage crowbar according to claim 6, it is characterised in that：First metal-oxide-semiconductor （Q1）With the second metal-oxide-semiconductor（Q2）It is that small-power N links up metal-oxide-semiconductor.

8. non-isolated CAN overvoltage crowbar according to claim 4, it is characterised in that：The overvoltage protection electricity Road（2）Also include first order absorption circuit（22）, the first order absorption circuit（22）Including two by bus common mode voltage clamping in The TVS pipe clamp circuit of voltage is set, each TVS pipe clamp circuit includes TVS pipe, RC parallel circuits, a TVS The one termination common mode inductance of pipe（L1）1 pin, another TVS pipe one termination common mode inductance（L1）4 pin, they another Reference ground is accessed after the concatenation RC parallel circuits of one end.

9. non-isolated CAN overvoltage crowbar according to claim 8, it is characterised in that：The clamper of the TVS pipe Voltage is less than the maximum tolerance bus level that the reference voltage is less than the CAN transceiver.

10. according to any described non-isolated CAN overvoltage crowbars of claim 1-9, it is characterised in that：It is described it is non-every At least it is applied to the CAN communication module of low-pressure electric automotive motor controller from CAN overvoltage crowbar.