CN112147477A - New energy automobile direct current charging equipment insulation monitoring system and method - Google Patents
New energy automobile direct current charging equipment insulation monitoring system and method Download PDFInfo
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- CN112147477A CN112147477A CN202011021154.0A CN202011021154A CN112147477A CN 112147477 A CN112147477 A CN 112147477A CN 202011021154 A CN202011021154 A CN 202011021154A CN 112147477 A CN112147477 A CN 112147477A
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- resistor
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/12—Testing dielectric strength or breakdown voltage ; Testing or monitoring effectiveness or level of insulation, e.g. of a cable or of an apparatus, for example using partial discharge measurements; Electrostatic testing
- G01R31/14—Circuits therefor, e.g. for generating test voltages, sensing circuits
Abstract
The invention discloses a system and a method for monitoring insulation of direct-current charging equipment of a new energy automobile. On the basis of the unbalanced bridge measurement method, only one path of switching device is introduced, so that the driving control mode of the measurement circuit during the monitoring period is simplified, the cost caused by the switching device is effectively reduced, and the effective implementation of the unbalanced bridge method is ensured.
Description
Technical Field
The invention belongs to the technical field of charging of new energy automobiles, and particularly relates to an insulation monitoring method.
Background
With the large-scale use of electric vehicles, new energy vehicle charging equipment, particularly direct current charging equipment, is widely used due to the characteristics of high charging speed and the like. Along with the implementation of national standard, the requirement is put forward to the personnel protection of electrocuting in the middle of new energy automobile charging process, in order to guarantee the charging safety of new energy automobile and personnel's personal safety, has strict requirement to the insulating security performance of new energy automobile charging equipment high voltage direct current generating line floating ground system.
In the traditional insulation monitoring method, the switching devices are simultaneously connected to the anode and cathode bridge arms of the unbalanced bridge, so that the measuring circuit needs to simultaneously drive and control the two switching devices during monitoring, the control mode is complex, and the cost of the two switching devices is relatively high.
Disclosure of Invention
In order to solve the technical problems mentioned in the background art, the invention provides a new energy automobile direct current charging equipment insulation monitoring system and method.
In order to achieve the technical purpose, the technical scheme of the invention is as follows:
a new energy automobile direct current charging equipment insulation monitoring system comprises a bridge arm resistance loop, a main controller, a positive electrode signal acquisition circuit, a negative electrode signal acquisition circuit, a switch driving circuit and a power supply module; the bridge arm resistance loop comprises a direct current power supply of a high-voltage direct current bus floating system, a first switch tube and first to eighth resistors, wherein the positive pole of the direct current power supply of the high-voltage direct current bus floating system is sequentially connected with the first resistor, the second resistor, the third resistor and the fourth resistor in series to form a positive bridge arm, the negative pole of the direct current power supply of the high-voltage direct current bus floating system is sequentially connected with the eighth resistor, the seventh resistor, the sixth resistor and the fifth resistor in series to form a negative bridge arm, the fourth resistor is connected with the fifth resistor in series and the serial connection point of the fourth resistor is connected with the system ground, the emitter of the first switch tube is connected with the serial connection point of the fifth resistor and the sixth resistor, the collector of the first switch tube is connected with the serial connection point of the seventh resistor and the eighth resistor, and the third resistor and, the acquisition voltage is Up, the fifth resistor and the sixth resistor form a negative bridge arm acquisition resistor, and the acquisition voltage is Un; the input end of the switch driving circuit is connected with the main controller, the output end of the switch driving circuit is connected with the grid electrode of the first switching tube, the input end of the positive electrode signal acquisition circuit acquires Up, the input end of the negative electrode signal acquisition circuit acquires Un, and the output end of the power supply module is connected with the power supply end of the main controller; the main controller sends a driving signal to the first switch tube through the switch driving circuit so as to control the on-off state of the first switch tube, the positive electrode signal acquisition circuit and the negative electrode signal acquisition circuit respectively acquire the Up and the Un under different switch tube states and transmit the Up and the Un to the main controller, and the main controller obtains an insulation monitoring result according to received voltage data.
Furthermore, the system also comprises a communication module, wherein the communication module is connected with a main controller, and the main controller performs data interaction with the monitoring center through the communication module.
Further, the communication module comprises an RS485 chip.
Further, the positive electrode signal acquisition circuit and the negative electrode signal acquisition circuit have the same structure and comprise operational amplifiers, first to fourth capacitors and ninth to eleventh resistors, wherein the operational amplifier adopts an LM158 chip, pin 1 of the LM158 chip is connected with pin 2, pin 3 of the LM158 chip is grounded, pin 4 of the LM158 chip is grounded through the first capacitor, pin 5 of the LM158 chip is sequentially connected in series with a tenth resistor and an eleventh resistor to serve as the input end of the whole signal acquisition circuit, the series connection point of the tenth resistor and the eleventh resistor is grounded through the third capacitor, pin 6 and pin 7 of the LM158 chip are connected, one end of the ninth resistor is connected with pin 6 of the LM158 chip, and the other end of the ninth resistor is grounded through the fourth capacitor and serves as the output end of the whole signal acquisition circuit.
Further, the switch driving circuit includes an isolation optocoupler module.
Further, the power module adopts a DC-DC isolation mode.
Furthermore, the main controller adopts a minimum system circuit with an STM8S103 single chip microcomputer as a core and comprises an external memory.
Based on the insulation monitoring method of the insulation monitoring system of the new energy automobile direct current charging equipment, the main controller sends a driving signal to the first switching tube, when the first switching tube is conducted, the first resistor, the second resistor, the third resistor and the fourth resistor form a positive bridge arm, and the equivalent resistor R of the positive bridge armc＝R1+R2+R3+R4The fifth resistor and the eighth resistor form a negative bridge arm, and the equivalent resistor R of the negative bridge arma＝R5+R8When Un is Un1, Up is Up 1; when the first switch tube is disconnected, the first, second, third and fourth resistors form a positive bridge arm, and the equivalent resistor R of the positive bridge armc＝R1+R2+R3+R4The fifth, sixth, seventh and eighth resistors form a negative bridge arm, and the equivalent resistor R of the negative bridge armb＝R5+R6+R7+R8When Un is Un2, Up is Up 2;
r is as defined above1～R8The resistance values of the first to eighth resistors are required to satisfy the following mathematical relationship:
the direct current power supply anode-to-ground insulation resistor R of the high-voltage direct current bus floating systempThe calculation method of (2) is as follows:
direct-current power supply anode-to-ground insulation resistor R of high-voltage direct-current bus floating systemnThe calculation method of (2) is as follows:
in the above formula, the first and second carbon atoms are,
and k ≠ m.
Adopt the beneficial effect that above-mentioned technical scheme brought:
on the basis of the unbalanced bridge measurement method, only one path of switching device is introduced, so that the driving control mode of the measurement circuit during the monitoring period is simplified, the cost caused by the switching device is effectively reduced, and the effective implementation of the unbalanced bridge method is ensured.
Drawings
FIG. 1 is a circuit diagram of the system of the present invention;
FIG. 2 is an equivalent circuit diagram of state 1 of the present invention;
FIG. 3 is an equivalent circuit diagram of State 2 of the invention;
FIG. 4 is a circuit diagram of the signal acquisition of the present invention;
FIG. 5 is a circuit diagram of a switch driver according to the present invention;
fig. 6 is a circuit diagram of a communication module according to the present invention.
Detailed Description
The technical scheme of the invention is explained in detail in the following with the accompanying drawings.
The invention designs an insulation monitoring system of direct-current charging equipment of a new energy automobile, which comprises a bridge arm resistance loop, a main controller, a positive electrode signal acquisition circuit, a negative electrode signal acquisition circuit, a switch driving circuit and a power supply module, as shown in figure 1.
The bridge arm resistance loop is formed by connecting a positive arm resistance and a negative arm resistance in series respectively. The positive pole and the negative pole of a direct current power supply Vs of the high-voltage direct current bus floating system are connected in series through bridge arm resistors R1, R2, R3 and R4 and bridge arm resistors R5, R6, R7 and R8, wherein a positive bridge arm is formed by R1, R2, R3 and R4; r5, R6, R7 and R8 form a negative bridge arm. The connection end of the resistor R4 and the resistor R5 is connected with the system ground PE. The connection end of the resistor R7 and the resistor R8 is connected with the collector of the switch tube S1, and the connection end of the resistor R5 and the resistor R6 is connected with the emitter of the switch tube S1. The resistor R3 and the resistor R4 form a bridge arm anode sampling resistor, and the sampling voltage of the bridge arm anode sampling resistor is Up. The resistor R5 and the resistor R6 form a bridge arm cathode sampling resistor, and the sampling voltage is Un. The positive pole of the direct current power supply Vs records the insulation resistance to be measured of the ground as the positive pole insulation resistance Rp, and the negative pole records the insulation resistance to be measured of the ground as the negative pole insulation resistance Rn.
Based on the insulation monitoring system of the direct current charging equipment of the new energy automobile, the calculation method of the ground insulation resistance comprises the following steps:
state 1: when the switching tube S1 is turned on, R1, R2, R3 and R4 form a positive bridge arm, the equivalent resistance Rc of the positive bridge arm is R1+ R2+ R3+ R4, the fifth resistance and the eighth resistance form a negative bridge arm, the equivalent resistance Ra of the negative bridge arm is R5+ R8, Un1, and Up 1. The equivalent circuit of the bridge arm resistance loop is shown in fig. 2.
The bridge arm resistance parameters need to satisfy the following mathematical relationship:
from the state 1 equivalent circuit KCL, KVL, in combination with the above formula:
state 2: the switching tube S1 is disconnected, the R1, the R2, the R3 and the R4 form a positive bridge arm, and the equivalent resistance Rc of the positive bridge arm is R1+ R2+ R3+ R4; r5, R6, R7, and R8 form a negative bridge arm, and in this case, the negative bridge arm equivalent resistance Rb is R5+ R6+ R7+ R8. In this case, Un is Un2 and Up is Up 2. The equivalent circuit of the bridge arm resistance loop is shown in fig. 3.
From the state 2 equivalent circuit KCL, KVL, we can obtain:
the bridge arm equivalent resistances Rc, Rb and Ra satisfy the following relational expression:
Rb＝k×Ra
Rc＝m×Ra
wherein k ≠ m.
According to the above-mentioned formulas, the following results are obtained,
direct-current power supply anode-to-ground insulation resistor R of high-voltage direct-current bus floating systemp：
Direct-current power supply anode-to-ground insulation resistor R of high-voltage direct-current bus floating systemn：
In this embodiment, the main controller may adopt a minimum system circuit using the STM8S103 single chip microcomputer as a core, and simultaneously includes an external memory, which may be used to record insulation fault data. The main controller has the main functions of executing an insulation resistance algorithm, reading and processing bridge arm acquisition signals, outputting switching tube driving signals, controlling communication, receiving and transmitting, and the like.
In this embodiment, the positive signal collecting circuit and the negative signal collecting circuit have the same structure, and as shown in fig. 4, the positive signal collecting circuit includes an operational amplifier U1, capacitors C1 to C4, and resistors R9 to R11, and the operational amplifier employs an LM158 chip. The resistor R11 and the capacitor C3 form a first-order low-pass filter circuit; the operational amplifier U1, the capacitors C1, C2 and C4 and the resistors R9 and R10 form a voltage sampling signal conditioning circuit which is used for amplifying and conditioning signal input and output.
In this embodiment, the switch drive circuit employs a optocoupler isolated mode, as shown in fig. 5, with the drive input signal provided by the main controller output. The isolation optocoupler SW1 and SW2 are connected in series to output switch signals, and a resistor R12 and a capacitor C5 form a switching tube to drive input signal conditioning.
In this embodiment, the power module provides the required power voltage for the whole system by using a DC-DC isolation method. The power supply inputs a wide range of voltage values of 9-36V, and outputs 5V voltage which can be used by the singlechip and 3.3V, +/-9V and 12V voltage required by other circuits.
In this embodiment, as shown in fig. 6, an RS485 communication mode conforming to the industrial Modbus communication protocol standard is used. The design of an isolation mode is adopted, and the Baud rate can reach 115200bps at most. An RS485 chip U2 is used as a core device of a communication module to provide a standard RS485 communication transceiving interface, and resistors R14, R15, R16, R17 and R18 and bidirectional diodes D1 and D2 jointly form a communication bus signal conditioning and protecting circuit.
The embodiments are only for illustrating the technical idea of the present invention, and the technical idea of the present invention is not limited thereto, and any modifications made on the basis of the technical scheme according to the technical idea of the present invention fall within the scope of the present invention.
Claims (8)
1. The utility model provides a new energy automobile direct current battery charging outfit insulation monitoring system which characterized in that: the device comprises a bridge arm resistance loop, a main controller, a positive electrode signal acquisition circuit, a negative electrode signal acquisition circuit, a switch driving circuit and a power module; the bridge arm resistance loop comprises a direct current power supply of a high-voltage direct current bus floating system, a first switch tube and first to eighth resistors, wherein the positive pole of the direct current power supply of the high-voltage direct current bus floating system is sequentially connected with the first resistor, the second resistor, the third resistor and the fourth resistor in series to form a positive bridge arm, the negative pole of the direct current power supply of the high-voltage direct current bus floating system is sequentially connected with the eighth resistor, the seventh resistor, the sixth resistor and the fifth resistor in series to form a negative bridge arm, the fourth resistor is connected with the fifth resistor in series and the serial connection point of the fourth resistor is connected with the system ground, the emitter of the first switch tube is connected with the serial connection point of the fifth resistor and the sixth resistor, the collector of the first switch tube is connected with the serial connection point of the seventh resistor and the eighth resistor, and the third resistor and, the acquisition voltage is Up, the fifth resistor and the sixth resistor form a negative bridge arm acquisition resistor, and the acquisition voltage is Un; the input end of the switch driving circuit is connected with the main controller, the output end of the switch driving circuit is connected with the grid electrode of the first switching tube, the input end of the positive electrode signal acquisition circuit acquires Up, the input end of the negative electrode signal acquisition circuit acquires Un, and the output end of the power supply module is connected with the power supply end of the main controller; the main controller sends a driving signal to the first switch tube through the switch driving circuit so as to control the on-off state of the first switch tube, the positive electrode signal acquisition circuit and the negative electrode signal acquisition circuit respectively acquire the Up and the Un under different switch tube states and transmit the Up and the Un to the main controller, and the main controller obtains an insulation monitoring result according to received voltage data.
2. The insulation monitoring system of the new energy automobile direct current charging equipment is characterized in that: the system also comprises a communication module, wherein the communication module is connected with a main controller, and the main controller performs data interaction with the monitoring center through the communication module.
3. The insulation monitoring system of the new energy automobile direct current charging equipment is characterized in that: the communication module comprises an RS485 chip.
4. The insulation monitoring system of the new energy automobile direct current charging equipment is characterized in that: the structure of the positive electrode signal acquisition circuit is the same as that of the negative electrode signal acquisition circuit, and the positive electrode signal acquisition circuit comprises an operational amplifier, first to fourth capacitors and ninth to eleventh resistors, wherein the operational amplifier adopts an LM158 chip, pin 1 of the LM158 chip is connected with pin 2, pin 3 of the LM158 chip is grounded, pin 4 of the LM158 chip is grounded through the first capacitor, pin 5 of the LM158 chip is sequentially connected in series with a tenth resistor and the eleventh resistor to serve as the input end of the whole signal acquisition circuit, the serial connection point of the tenth resistor and the eleventh resistor is grounded through the third capacitor, pin 6 and pin 7 of the LM158 chip are connected, one end of the ninth resistor is connected with pin 6 of the LM158 chip, and the other end of the ninth resistor is grounded through the fourth capacitor and serves as the output end of the whole signal acquisition circuit.
5. The insulation monitoring system of the new energy automobile direct current charging equipment is characterized in that: the switch driving circuit comprises an isolation optocoupler module.
6. The insulation monitoring system of the new energy automobile direct current charging equipment is characterized in that: the power module adopts a DC-DC isolation mode.
7. The insulation monitoring system of the new energy automobile direct current charging equipment is characterized in that: the main controller adopts a minimum system circuit with an STM8S103 single chip microcomputer as a core and comprises an external memory.
8. The insulation monitoring method of the insulation monitoring system of the new energy automobile direct current charging equipment based on the claim 1 is characterized in that: the main controller sends a driving signal to the first switching tube, when the first switching tube is conducted, the first resistor, the second resistor, the third resistor and the fourth resistor form a positive bridge arm, and the equivalent resistor R of the positive bridge armc＝R1+R2+R3+R4Fifth resistor and eighth resistorNegative bridge arm, equivalent resistance R of negative bridge arma＝R5+R8When Un is Un1, Up is Up 1; when the first switch tube is disconnected, the first, second, third and fourth resistors form a positive bridge arm, and the equivalent resistor R of the positive bridge armc＝R1+R2+R3+R4The fifth, sixth, seventh and eighth resistors form a negative bridge arm, and the equivalent resistor R of the negative bridge armb＝R5+R6+R7+R8When Un is Un2, Up is Up 2;
r is as defined above1～R8The resistance values of the first to eighth resistors are required to satisfy the following mathematical relationship:
the direct current power supply anode-to-ground insulation resistor R of the high-voltage direct current bus floating systempThe calculation method of (2) is as follows:
direct-current power supply anode-to-ground insulation resistor R of high-voltage direct-current bus floating systemnThe calculation method of (2) is as follows:
in the above formula, the first and second carbon atoms are,
and k ≠ m.
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| CN202011021154.0A CN112147477A (en) | 2020-09-25 | 2020-09-25 | New energy automobile direct current charging equipment insulation monitoring system and method |
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| CN202011021154.0A CN112147477A (en) | 2020-09-25 | 2020-09-25 | New energy automobile direct current charging equipment insulation monitoring system and method |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| TWI790148B (en) * | 2022-03-22 | 2023-01-11 | 台達電子工業股份有限公司 | Insulation resistance detection circuit and method of detecting insulation resistance |
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| CN203587701U (en) * | 2013-09-30 | 2014-05-07 | 天津瑞能电气有限公司 | Online detection circuit for photovoltaic inverter ground insulation resistance |
| CN104104330A (en) * | 2014-07-15 | 2014-10-15 | 安徽启光能源科技研究院有限公司 | Insulation detection system and insulation detection method for photovoltaic energy storage system |
| CN207408480U (en) * | 2017-10-30 | 2018-05-25 | 科大智能（合肥）科技有限公司 | A kind of direct-current charging post detecting system |
| CN111208350A (en) * | 2020-03-11 | 2020-05-29 | 上海度普新能源科技有限公司 | Insulation detection circuit and energy storage charging equipment |
| CN111381138A (en) * | 2020-04-26 | 2020-07-07 | 台州联胜电气技术有限公司 | Insulation monitoring system and method for direct current charging pile |
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2020
- 2020-09-25 CN CN202011021154.0A patent/CN112147477A/en not_active Withdrawn
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103149406A (en) * | 2013-01-31 | 2013-06-12 | 北京人民电器厂有限公司 | Bridge used for direct current insulation monitoring device and running method thereof |
| CN203587701U (en) * | 2013-09-30 | 2014-05-07 | 天津瑞能电气有限公司 | Online detection circuit for photovoltaic inverter ground insulation resistance |
| CN104104330A (en) * | 2014-07-15 | 2014-10-15 | 安徽启光能源科技研究院有限公司 | Insulation detection system and insulation detection method for photovoltaic energy storage system |
| CN207408480U (en) * | 2017-10-30 | 2018-05-25 | 科大智能（合肥）科技有限公司 | A kind of direct-current charging post detecting system |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
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| TWI790148B (en) * | 2022-03-22 | 2023-01-11 | 台達電子工業股份有限公司 | Insulation resistance detection circuit and method of detecting insulation resistance |
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