CN113075457A - Vehicle-mounted charger and alternating current side insulation detection circuit and method thereof - Google Patents
Vehicle-mounted charger and alternating current side insulation detection circuit and method thereof Download PDFInfo
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- CN113075457A CN113075457A CN202110324875.7A CN202110324875A CN113075457A CN 113075457 A CN113075457 A CN 113075457A CN 202110324875 A CN202110324875 A CN 202110324875A CN 113075457 A CN113075457 A CN 113075457A
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- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R27/00—Arrangements for measuring resistance, reactance, impedance, or electric characteristics derived therefrom
- G01R27/02—Measuring real or complex resistance, reactance, impedance, or other two-pole characteristics derived therefrom, e.g. time constant
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Abstract
The invention provides a vehicle-mounted charger and an alternating current side insulation detection circuit and method thereof.A partial voltage at an ideal midpoint and a partial voltage at a vehicle body of two poles of an alternating current side of the vehicle-mounted charger are collected when the vehicle-mounted charger reversely outputs, and a relative difference value between the two partial voltages is determined; then, judging the amplitude of the alternating current component in the relative difference value, and if the amplitude is larger than a preset threshold value, judging that the insulation impedance of the alternating current side of the vehicle-mounted charger is abnormal; compared with the scheme of detecting the specific impedance value in the prior art, the alternating current side insulation detection method of the vehicle-mounted charger provided by the invention can determine whether the insulation impedance of the alternating current side is abnormal or not only by comparing and judging the differential pressure of the two electrodes of the alternating current side of the vehicle-mounted charger at the ideal midpoint partial pressure and the partial pressure of the vehicle body, the circuit structure is simple, and the system cost is reduced.
Description
Technical Field
The invention relates to the technical field of charging equipment, in particular to a vehicle-mounted charger and an alternating current side insulation detection circuit and method thereof.
Background
With the rapid development of new energy automobiles in the market and under the promotion of governments, the market share of electric automobiles is continuously increasing. The vehicle-mounted charger is used as an essential part for charging electric vehicles, particularly passenger vehicles, and the safety and reliability of the vehicle are directly affected by the quality of the vehicle-mounted charger. Moreover, due to the increase of market demand and the improvement of technology, the functions of the vehicle-mounted charger are more and more abundant, and the bidirectional power flow becomes a development trend.
When the vehicle-mounted charger reversely outputs alternating current to an alternating current load, the insulation condition of the alternating current output by the vehicle-mounted charger to a vehicle body needs to be detected so as to avoid component damage caused by insulation abnormity and personnel electric shock risks. The conventional detection method comprises an off-line detection mode and an on-line detection mode, the off-line detection mode is only used for detecting before the work of a power supply, the on-line detection mode can be used for detecting when the alternating current is output in a real-time inversion mode, the power output can be timely turned off when the insulation is abnormal, and the reliability is higher.
In the prior art, a relatively effective online detection method is as follows: a voltage division circuit is respectively arranged on the zero line and the live line output by the inverter circuit to detect the voltage division of two alternating current output poles at the position of the vehicle body, and then the detection result is added and processed, so that the insulation detection and the abnormity judgment are realized. However, this online detection method has problems of a complicated detection circuit and high cost.
Disclosure of Invention
In view of this, embodiments of the present invention provide a vehicle-mounted charger and an ac side insulation detection circuit and method thereof, which solve the problems of complex circuit and high cost in the prior art.
In order to achieve the above purpose, the embodiments of the present invention provide the following technical solutions:
the invention provides a first aspect of an alternating current side insulation detection method of a vehicle-mounted charger, which comprises the following steps:
when the vehicle-mounted charger reversely outputs, collecting partial pressure at an ideal midpoint and partial pressure at a vehicle body of two poles of an alternating current side of the vehicle-mounted charger;
determining a relative difference between the desired midpoint partial pressure and the body partial pressure;
judging whether the amplitude of the alternating current component in the relative difference value is larger than a preset threshold value or not;
and if so, determining that the insulation resistance on the alternating current side is abnormal.
Preferably, determining the relative difference between the desired midpoint partial pressure and the body partial pressure comprises:
biasing the partial pressure at the ideal midpoint, and lifting the potential difference between the partial pressure at the ideal midpoint and the partial pressure at the vehicle body;
and processing the potential difference to obtain the relative difference value.
Preferably, the processing the potential difference comprises:
and performing impedance matching processing and filtering processing on the potential difference.
The second aspect of the present invention provides an insulation detection circuit on the ac side of a vehicle-mounted charger, including: the sampling voltage division circuit, the difference value determination circuit and the controller; wherein:
the sampling voltage division circuit is used for collecting the voltage division of two poles of the alternating current side of the vehicle-mounted charger at an ideal midpoint when the vehicle-mounted charger reversely outputs;
the difference value determining circuit is used for determining a relative difference value between the ideal midpoint partial pressure and the vehicle body partial pressure; when the partial pressure at the vehicle body is output reversely by the vehicle-mounted charger, the two poles at the alternating current side form the partial pressure at the vehicle body due to the existence of insulation impedance between the vehicle body and the two poles at the alternating current side;
the controller is used for judging whether the amplitude of the alternating current component in the relative difference value is larger than a preset threshold value or not; and if so, determining that the insulation resistance on the alternating current side is abnormal.
Preferably, two ports of an input end of the sampling voltage division circuit are respectively connected with two poles of the alternating current side, and an ideal midpoint in the sampling voltage division circuit is used as an output end of the sampling voltage division circuit and outputs the voltage division of the ideal midpoint.
Preferably, the sampling voltage-dividing circuit includes: at least two voltage dividing devices; wherein:
and the voltage dividing devices are connected in series, two ends of the voltage dividing devices after being connected in series are used as two ports of the input end of the sampling voltage dividing circuit, and a point, corresponding to the two poles of the alternating current side, of the serial branch circuit with equal voltage division is used as the ideal midpoint.
Preferably, the difference determination circuit includes: a bias circuit and a difference comparison processing circuit;
the bias circuit is used for biasing the partial pressure at the ideal midpoint and lifting the potential difference between the partial pressure at the ideal midpoint and the partial pressure at the vehicle body;
the difference comparison processing circuit is used for processing the potential difference to obtain the relative difference.
Preferably, the bias circuit includes: a bias power supply and a bias voltage dividing circuit; wherein:
the middle point of the bias voltage dividing circuit is connected with the ideal midpoint of the sampling voltage dividing circuit, and one end of the bias voltage dividing circuit is connected with the anode of the bias power supply;
and the cathode of the bias power supply and the other end of the bias voltage division circuit are both connected with the vehicle body.
Preferably, the bias voltage dividing circuit includes: at least two bias voltage dividing resistors; wherein:
the bias voltage dividing resistors are connected in series, two ends of the series connection are respectively used as two ends of the bias voltage dividing circuit, and any point in the series connection branch is used as a middle point of the bias voltage dividing circuit.
Preferably, an input end of the difference comparison processing circuit is connected to the ideal midpoint of the sampling voltage division circuit, and an output end of the difference comparison processing circuit is connected to an input end of the controller.
Preferably, the difference comparison processing circuit includes: an impedance matching circuit and a filter circuit; wherein:
the input end of the impedance matching circuit is used as the input end of the difference comparison processing circuit, and the output end of the impedance matching circuit is connected to the input end of the filter circuit;
and the output end of the filter circuit is used as the output end of the difference value comparison processing circuit.
Preferably, the impedance matching circuit is an operational amplifier; wherein:
the non-inverting input end of the operational amplifier is used as the input end of the impedance matching circuit, the inverting input end of the operational amplifier is connected with the output end of the operational amplifier, and the connection point is used as the output end of the impedance matching circuit.
Preferably, the filter circuit includes: a first resistor and a first capacitor; wherein:
one end of the first resistor is used as the input end of the filter circuit;
the other end of the first resistor is connected with one end of the first capacitor, and a connection point is used as the output end of the filter circuit;
the other end of the first capacitor is connected with the vehicle body.
Preferably, the controller is any one of a micro control unit, a digital signal processor or a programmable gate array.
The invention also provides a vehicle-mounted charger which is a bidirectional vehicle-mounted charger or an all-in-one bidirectional vehicle-mounted power supply integrated module, and the alternating current side of the vehicle-mounted charger is provided with the alternating current side insulation detection circuit of the vehicle-mounted charger.
Based on the alternating current side insulation detection method of the vehicle-mounted charger, when the vehicle-mounted charger reversely outputs, the two poles of the alternating current side are collected at the ideal midpoint partial pressure and the vehicle body partial pressure in real time, and the relative difference between the ideal midpoint partial pressure and the vehicle body partial pressure is determined; then, according to the characteristics that two poles of the alternating current side of the vehicle-mounted charger have equal impedance and equal partial pressure to the vehicle body when the insulation is normal, and the two poles of the alternating current side have unequal impedance and unequal partial pressure to the vehicle body when the insulation is abnormal, judging the amplitude of the alternating current component in the relative difference value, and if the amplitude is greater than a preset threshold value, judging that the insulation impedance of the alternating current side of the vehicle-mounted charger is abnormal; compared with the scheme of detecting the specific impedance value in the prior art, the alternating current side insulation detection method of the vehicle-mounted charger provided by the invention can determine whether the insulation impedance of the alternating current side is abnormal or not only by comparing and judging the differential pressure of the two electrodes of the alternating current side of the vehicle-mounted charger at the ideal midpoint partial pressure and the partial pressure of the vehicle body, the circuit structure is simple, and the system cost is reduced.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the provided drawings without creative efforts.
Fig. 1 is a flowchart of an ac side insulation detection method of a vehicle-mounted charger according to an embodiment of the present invention;
fig. 2 is a schematic structural diagram of actual insulation impedance and virtual impedance of two poles at the alternating current side of the vehicle-mounted charger according to the embodiment of the invention;
fig. 3 is a flowchart of another method for detecting insulation on the ac side of a vehicle-mounted charger according to an embodiment of the present invention;
FIG. 4 is a voltage waveform diagram of two poles on the AC side of the vehicle-mounted charger of FIG. 2 versus an ideal midpoint;
fig. 5 is a schematic structural diagram of an ac-side insulation detection circuit of a vehicle-mounted charger according to another embodiment of the present invention;
fig. 6 is a schematic structural diagram of a bias circuit in an ac-side insulation detection circuit of a vehicle-mounted charger according to another embodiment of the present invention;
fig. 7 is a schematic structural diagram of a difference value determining circuit in an alternating current side insulation detecting circuit of a vehicle-mounted charger according to another embodiment of the present invention;
fig. 8 and fig. 9 are schematic structural diagrams of a bias circuit and a difference comparison processing circuit in a difference determination circuit of an alternating current side insulation detection circuit of a vehicle-mounted charger according to another embodiment of the present invention;
fig. 10 is a schematic structural diagram of an ac-side insulation detection circuit of a vehicle-mounted charger according to another embodiment of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
In this application, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.
The alternating current side insulation detection method of the vehicle-mounted charger provided by the embodiment of the invention can solve the problem of high system cost in the prior art.
Fig. 1 shows a flow chart of the ac side insulation detection method, which includes:
s101, collecting partial pressure of two poles of an alternating current side of the vehicle-mounted charger at an ideal midpoint and partial pressure of the vehicle body when the vehicle-mounted charger reversely outputs.
When the vehicle-mounted charger reversely outputs, the vehicle-mounted charger also operates in an inversion state to externally output alternating current. As shown in fig. 2, AC is the alternating current when the vehicle-mounted charger reversely outputs, the live line L and the zero line N are two poles on the alternating current side, and assuming that X1 and X2 are the actual insulation impedances of the live line L and the zero line N on the alternating current side to the vehicle body, respectively, that is, the voltage at the o1 point is the voltage divided by the two poles on the alternating current side of the vehicle-mounted charger at the vehicle body, and by adding two impedances R equal to the zero line N on the alternating current side relative to the o point, the o point can be regarded as an ideal midpoint. It should be noted that the schematic diagram of the impedance R on the ac side shown in fig. 2 is only an example of the embodiment of the present invention, and is not limited thereto, and in practical application, the impedances R on both sides of the ideal midpoint o may be in a series-parallel connection form of any number of impedances, and as long as the impedance values on both sides of the ideal midpoint o are the same, the voltage values of the ideal midpoint o relative to the two poles on the ac side can be ensured to be equal; for example, 3 resistors R1, R2 and R3 may be provided, and the resistance relationship is R1+ R2 — R3, a connection point at which one end of the R1 and the R2 connected in series is connected to R3 is an ideal midpoint o, and the same may be true when other numbers of resistors with different resistances are provided; the impedance R is not limited to a resistor, and may be a capacitor, an inductor, an arbitrary combination thereof, or the like.
And S102, determining a relative difference value between the partial pressure at the ideal midpoint and the partial pressure at the vehicle body.
When the vehicle-mounted charger reversely outputs alternating current, if the insulation impedance of two poles of the alternating current side of the vehicle-mounted charger is normal, the impedance of the two poles of the alternating current side to the vehicle body is equal, namely the partial voltage at the ideal midpoint is equal to the partial voltage at the vehicle body; if the insulation impedance of the two alternating-current side poles is abnormal, the impedance of the two alternating-current side poles to the vehicle body is not equal, namely the partial pressure at the ideal midpoint is not equal to the partial pressure at the vehicle body any more.
Therefore, after the ideal midpoint partial pressure and the vehicle body partial pressure are acquired, the relative difference between the ideal midpoint partial pressure and the vehicle body partial pressure is further calculated to detect whether the vehicle body insulation impedance is abnormal, and the calculation process can be as shown in fig. 3:
s201, offsetting the partial pressure at the ideal midpoint, and lifting the potential difference between the partial pressure at the ideal midpoint and the partial pressure at the vehicle body.
As shown in fig. 2, theoretically, the voltage of two poles on the alternating current side of the vehicle-mounted charger relative to the ideal midpoint does not change with the change of the output alternating current, specifically: assuming that the output of the live line L and the zero line N is 220V/50Hz alternating current, the voltage between the live line L and the point o
Voltage between zero line N and o point
The waveform diagram is shown in fig. 4, it can be seen that the amplitudes of the two are the same, and the phases are opposite, but the o point can be regarded as a potential quiescent point and does not change along with the change of the voltages of the two electrodes of the output alternating current; therefore, if the two poles on the alternating current side of the vehicle-mounted charger have equal voltage division at the ideal midpoint and the vehicle body, the insulation resistance on the alternating current side can be considered to be normal.
That is, if the insulation resistance of the two poles on the AC side is positiveNormally, the impedance X1 is equal to the impedance X2, and the o1 point is equal to the o point. When the impedance X1 is not equal to the impedance X2, a potential difference exists between the point o1 and the ideal midpoint o, and the potential difference is an alternating current and can change along with the change of the voltages of two poles of the alternating current; as shown in fig. 2, when X1 and X2 are pure resistors, the potential difference between o1 and o is expressed as:
the potential difference Uo1-oThe waveform diagram of the ac vector is shown in fig. 4. Then, in order to avoid the negative voltage difference of the ideal midpoint o relative to the vehicle body ground and facilitate the subsequent signal processing, the potential difference U is processedo1-oIs biased, i.e. its ac component is raised by a dc bias, at which time the potential difference Uo1-oAn alternating current component is superimposed on the direct current component.
And S202, processing the potential difference to obtain a relative difference value.
In practice, processing the potential difference may include: the potential difference is subjected to impedance matching processing and filtering processing, but is not limited thereto.
After the relative difference is obtained, step S103 is performed.
S103, judging whether the amplitude of the alternating current component in the relative difference value is larger than a preset threshold value.
For the vehicle-mounted charger, when the vehicle-mounted charger outputs the alternating current to the outside, if the two poles on the alternating current side are normally and equally insulated from the vehicle body, the vehicle body and the ideal midpoint can be considered as equipotential, that is, the voltage at the point o1 is equal to the voltage at the point o. However, if an insulation abnormality occurs in a certain pole pair on the ac side, the insulation resistances of the two pole pairs on the ac side to the vehicle body are no longer equal, and there is a potential difference between the point o1 and the point o, and the larger the potential difference is, the larger the difference between the insulation resistances of the vehicle body is, that is, the larger the difference between X1 and X2 is; therefore, if the amplitude of the alternating current component in the relative difference value is greater than a preset threshold value, it can be determined that the insulation impedance of the alternating current side of the vehicle-mounted charger is abnormal; that is, if the determination result in step S103 is yes, step S104 is executed. The specific value of the preset threshold may be determined by a skilled person according to specific situations, for example, the voltage may be a voltage division of a minimum resistance required for vehicle body insulation, and all of them are within the protection scope of the embodiment of the present invention.
And S104, determining that the insulation resistance on the alternating current side is abnormal.
According to the alternating current side insulation detection method of the vehicle-mounted charger, whether insulation resistance of the alternating current side is abnormal can be determined only by comparing and judging the relative difference value of the partial pressure at the ideal midpoint and the partial pressure at the vehicle body, a complex circuit is not required to be added, and compared with the scheme of detecting a specific impedance value in the prior art, the system cost is reduced. In addition, although the sampling precision of insulation detection is reduced, the accurate calculation of the insulation resistance value is not required in the design standard of the vehicle-mounted charger, so that the fault occurrence and serious conditions of single-point insulation failure at the AC side can be detected by the detection method, and the basic requirement of insulation detection at the inverter AC side can be met.
Another embodiment of the present invention provides an ac side insulation detection circuit of a vehicle-mounted charger, a structure of which is schematically shown in fig. 5, including: a sampling voltage dividing circuit 110, a difference value determining circuit 120, and a controller 130; wherein:
the sampling voltage division circuit 110 is used for collecting the voltage division of two poles at the alternating current side of the vehicle-mounted charger at an ideal midpoint when the vehicle-mounted charger reversely outputs.
The difference determination circuit 120 is used for determining a relative difference between the ideal midpoint partial pressure and the vehicle body partial pressure; the voltage division at the vehicle body is the voltage division formed by two poles at the alternating current side of the vehicle body due to the existence of insulation resistance (shown as X1 and X2 in fig. 2 or fig. 10) between the vehicle body and the two poles at the alternating current side when the vehicle-mounted charger reversely outputs, namely, the voltage at the o1 point.
The controller 130 is configured to determine whether an amplitude of the alternating current component in the relative difference is greater than a preset threshold; and if the judgment result is yes, determining that the insulation resistance on the alternating current side is abnormal.
As shown in fig. 5, two ports of the input end of the sampling voltage-dividing circuit 110 are respectively connected to two poles (shown as L and N in fig. 2 or fig. 5) on the ac side, and an ideal midpoint (shown as o in fig. 2 and fig. 6) in the sampling voltage-dividing circuit 110 serves as the output end of the sampling voltage-dividing circuit 110 to output the divided voltage at the ideal midpoint.
In practical applications, the sampling voltage divider circuit 110 includes: at least two voltage dividing devices; the voltage divider may be any one of a resistor, a capacitor, or an inductor, or a combination of two or three of the resistor, the capacitor, and the inductor, which is within the protection scope of the embodiment of the present invention. In fig. 6, a resistor R is taken as an example of a voltage divider, each voltage divider is connected in series, two ends of the series are taken as two ports of an input end of the sampling voltage divider 110, and a point of the series branch circuit, which has equal voltage division with respect to two poles on the ac side, is taken as the ideal midpoint; as shown in fig. 6, assuming that the resistances of the two resistors R are equal, the ideal midpoint is the connection point o of the two resistors R. In practical application, the impedances R on both sides of the ideal midpoint o can be in a series-parallel connection mode of any number of impedances, and as long as the impedance values on both sides of the ideal midpoint o are the same, the voltage amplitudes between the live line L and the zero line N on the AC side and the ideal midpoint o can be ensured to be equal; for example, 3 resistors R1, R2, and R3 may be provided, and the resistance relationship is R1+ R2 — R3, and a connection point at which one end of the R1 and the R2 connected in series is connected to R3 is the ideal midpoint o.
As can be seen from the determination of the relative difference between the ideal midpoint divided voltage and the vehicle body divided voltage described in the above embodiment, the difference determination circuit 120 preferably includes: a bias circuit 210 and a difference comparison processing circuit 220; the structure diagram is shown in fig. 7, wherein the bias circuit 210 is used for biasing the voltage at the ideal midpoint and raising the potential difference between the voltage at the ideal midpoint and the voltage at the vehicle body; the difference comparing circuit 220 is used for processing the potential difference to obtain a relative difference.
The bias circuit 210 includes: a bias supply (shown as VCC in fig. 8) and a bias voltage divider circuit. In practical application, the bias voltage dividing circuit is composed of at least two bias voltage dividing resistors (shown as Rb1 and Rb2 in fig. 8), each bias voltage dividing resistor is connected in series, two ends of the series connection are respectively used as two ends of the bias voltage dividing circuit, and any point in a series branch is used as a middle point of the bias voltage dividing circuit; the embodiment of the invention takes the number of the bias divider resistors as two for example to show, and the structural schematic diagram is shown in fig. 8; the middle point of the bias voltage dividing circuit is connected with the ideal middle point of the sampling voltage dividing circuit 110, one end of the bias voltage dividing circuit is connected with the anode of the bias power supply, and the cathode of the bias power supply and the other end of the bias voltage dividing circuit are both connected with the vehicle body.
It should be noted that the bias circuit 210 biases the voltage at the ideal midpoint, and the specific process of raising the potential difference between the voltage at the ideal midpoint and the voltage at the vehicle body is as follows: the bias voltage-dividing circuit generates bias voltage, the bias voltage is used for carrying out bias on voltage division at the ideal midpoint, the potential difference alternating-current component is lifted through direct-current bias, and at the moment, the potential difference is lifted to: VCC Rb2/(Rb1+ Rb 2); for example, assuming that the bias power supply voltage VCC is 3.3V and Rb1 is Rb2, the bias voltage of the ideal midpoint o is 1.65V, and at this time, if the insulation resistances of the output ac sides L and N to the vehicle body are equal, that is, X1 is X2, the voltage difference between the ideal midpoint o and the vehicle body is a pure dc amount of 1.65V; when X1 is not equal to X2, the vehicle body has an alternating current component relative to the ideal midpoint, and at the moment, the potential difference between the ideal midpoint o and the partial voltage of the vehicle body is superposed with the alternating current component besides the 1.65V direct current component; and, the more X1 differs from X2, the larger the amplitude of the AC component; in the limit case, for example, when the output ac side L pole is short-circuited to the vehicle body, that is, X1 is 0, the amplitude of the potential difference ac component between the ideal midpoint o and the partial voltage at the vehicle body is the largest.
The difference comparison processing circuit 220 includes: an impedance matching circuit and a filter circuit; wherein, the input end of the impedance matching circuit is used as the input end of the difference comparison processing circuit 220, and the output end of the impedance matching circuit is connected to the input end of the filter circuit; the output of the filter circuit is used as the output of the difference comparison circuit 220. The impedance matching circuit is used for performing impedance matching on the potential difference lifted by the bias circuit 210, and then sending the potential difference to the filter circuit, and the filter circuit performs filtering processing to obtain a relative difference value between the ideal midpoint partial voltage and the vehicle body partial voltage.
In practical application, as shown in fig. 9, the impedance matching circuit may be an operational amplifier, a non-inverting input terminal of the operational amplifier serves as an input terminal of the impedance matching circuit, an inverting input terminal of the operational amplifier is connected to an output terminal of the operational amplifier, and a connection point serves as an output terminal of the impedance matching circuit; the filter circuit can be composed of a first resistor R1 and a first capacitor C1, and one end of the first resistor R1 is used as an input end of the filter circuit; the other end of the first resistor R1 is connected with one end of the first capacitor C1, and the connection point is used as the output end of the filter circuit; the other end of the first capacitor C1 is connected with the vehicle body; it should be noted that the impedance matching circuit and the filter circuit according to the embodiment of the present invention are not limited thereto, and other impedance matching circuits and filter circuits in the related art may be used.
Then, the difference comparison processing circuit 220 sends the relative difference to a sampling port of the controller 130, and the controller 130 determines whether the amplitude of the alternating current component in the relative difference is greater than a preset threshold; and if the judgment result is yes, determining that the insulation resistance on the alternating current side is abnormal. The controller 130 is any one of a micro control unit, a digital signal processor, or a programmable gate array, and is within the protection scope of the embodiment of the present invention.
Based on the structural schematic diagrams shown in fig. 5 to 9, a preferred structural schematic diagram of the ac-side insulation detection circuit of the vehicle-mounted charger according to the embodiment of the present invention is shown in fig. 10, but is not limited thereto.
According to the alternating current side insulation detection circuit of the vehicle-mounted charger, the difference value between the partial voltage of two poles of the alternating current side of the vehicle-mounted charger at the position of the vehicle body and the partial voltage of the alternating current side of the vehicle-mounted charger at the ideal midpoint can be determined only by adding the sampling voltage division circuit 110 and the difference value determination circuit 120, and then whether the insulation impedance is abnormal or not is determined by comparing the difference value; that is, the alternating current side insulation detection circuit of the vehicle-mounted charger of the embodiment can judge the insulation resistance only by adding a small number of voltage dividing resistors and by simple signal processing, and compared with the prior art, the circuit structure is simple and the cost is low. Although a specific insulation resistance value cannot be detected, the difference between the X1 and X2 resistances can be detected, and when the difference is a certain degree, the insulation on the alternating current side can be judged to be in a problem; the purpose is whether the insulation of the alternating current side is small to a dangerous range or not, and if so, a signal can be directly output and maintenance is prompted.
The rest of the principle is the same as the above embodiments, and is not described in detail here.
Another embodiment of the present invention provides a vehicle-mounted charger, wherein an alternating current side insulation detection circuit of the vehicle-mounted charger provided in the above embodiments is disposed on an output alternating current side of the vehicle-mounted charger, specifically, the vehicle-mounted charger may be a bidirectional vehicle-mounted charger or an all-in-one bidirectional vehicle-mounted power supply integrated module, and a charging circuit structure of the vehicle-mounted charger is the same as that of the vehicle-mounted charger in the prior art, and is not described again.
The rest of the principle is the same as the above embodiments, and is not described in detail here.
The embodiments in the present specification are described in a progressive manner, and the same and similar parts among the embodiments are referred to each other, and each embodiment focuses on the differences from the other embodiments. In particular, the system or system embodiments are substantially similar to the method embodiments and therefore are described in a relatively simple manner, and reference may be made to some of the descriptions of the method embodiments for related points. The above-described system and system embodiments are only illustrative, wherein the units described as separate parts may or may not be physically separate, and the parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution of the present embodiment. One of ordinary skill in the art can understand and implement it without inventive effort.
Those of skill would further appreciate that the various illustrative elements and algorithm steps described in connection with the embodiments disclosed herein may be implemented as electronic hardware, computer software, or combinations of both, and that the various illustrative components and steps have been described above generally in terms of their functionality in order to clearly illustrate this interchangeability of hardware and software. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the implementation. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present invention.
In the above description of the disclosed embodiments, the features described in the embodiments in this specification may be replaced or combined with each other to enable those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims (15)
1. An alternating current side insulation detection method of a vehicle-mounted charger is characterized by comprising the following steps:
when the vehicle-mounted charger reversely outputs, collecting partial pressure at an ideal midpoint and partial pressure at a vehicle body of two poles of an alternating current side of the vehicle-mounted charger;
determining a relative difference between the desired midpoint partial pressure and the body partial pressure;
judging whether the amplitude of the alternating current component in the relative difference value is larger than a preset threshold value or not;
and if so, determining that the insulation resistance on the alternating current side is abnormal.
2. The method for detecting the insulation on the alternating current side of the vehicle-mounted charger according to claim 1, wherein the step of determining the relative difference between the partial voltage at the ideal midpoint and the partial voltage at the vehicle body comprises the following steps:
biasing the partial pressure at the ideal midpoint, and lifting the potential difference between the partial pressure at the ideal midpoint and the partial pressure at the vehicle body;
and processing the potential difference to obtain the relative difference value.
3. The method for detecting the insulation on the alternating current side of the vehicle-mounted charger according to claim 2, wherein the processing of the potential difference comprises:
and performing impedance matching processing and filtering processing on the potential difference.
4. The utility model provides an exchange side insulation detection circuit of on-vehicle machine that charges which characterized in that includes: the sampling voltage division circuit, the difference value determination circuit and the controller; wherein:
the sampling voltage division circuit is used for collecting the voltage division of two poles of the alternating current side of the vehicle-mounted charger at an ideal midpoint when the vehicle-mounted charger reversely outputs;
the difference value determining circuit is used for determining a relative difference value between the ideal midpoint partial pressure and the vehicle body partial pressure; when the partial pressure at the vehicle body is output reversely by the vehicle-mounted charger, the two poles at the alternating current side form the partial pressure at the vehicle body due to the existence of insulation impedance between the vehicle body and the two poles at the alternating current side;
the controller is used for judging whether the amplitude of the alternating current component in the relative difference value is larger than a preset threshold value or not; and if so, determining that the insulation resistance on the alternating current side is abnormal.
5. The alternating current side insulation detection circuit of the vehicle-mounted charger according to claim 4, wherein two ports of an input end of the sampling voltage division circuit are respectively connected with two poles of the alternating current side, and an ideal midpoint in the sampling voltage division circuit is used as an output end of the sampling voltage division circuit to output divided voltage at the ideal midpoint.
6. The alternating current side insulation detection circuit of the vehicle-mounted charger according to claim 5, wherein the sampling voltage division circuit comprises: at least two voltage dividing devices; wherein:
and the voltage dividing devices are connected in series, two ends of the voltage dividing devices after being connected in series are used as two ports of the input end of the sampling voltage dividing circuit, and a point, corresponding to the two poles of the alternating current side, of the serial branch circuit with equal voltage division is used as the ideal midpoint.
7. The alternating current side insulation detection circuit of the vehicle-mounted charger according to any one of claims 4 to 6, wherein the difference value determination circuit comprises: a bias circuit and a difference comparison processing circuit;
the bias circuit is used for biasing the partial pressure at the ideal midpoint and lifting the potential difference between the partial pressure at the ideal midpoint and the partial pressure at the vehicle body;
the difference comparison processing circuit is used for processing the potential difference to obtain the relative difference.
8. The alternating current side insulation detection circuit of the vehicle-mounted charger according to claim 7, wherein the bias circuit comprises: a bias power supply and a bias voltage dividing circuit; wherein:
the middle point of the bias voltage dividing circuit is connected with the ideal midpoint of the sampling voltage dividing circuit, and one end of the bias voltage dividing circuit is connected with the anode of the bias power supply;
and the cathode of the bias power supply and the other end of the bias voltage division circuit are both connected with the vehicle body.
9. The alternating current side insulation detection circuit of the vehicle-mounted charger according to claim 8, wherein the bias voltage division circuit comprises: at least two bias voltage dividing resistors; wherein:
the bias voltage dividing resistors are connected in series, two ends of the series connection are respectively used as two ends of the bias voltage dividing circuit, and any point in the series connection branch is used as a middle point of the bias voltage dividing circuit.
10. The alternating current side insulation detection circuit of the vehicle-mounted charger according to claim 7, wherein an input end of the difference comparison processing circuit is connected to an ideal midpoint of the sampling voltage division circuit, and an output end of the difference comparison processing circuit is connected to an input end of the controller.
11. The ac side insulation detection circuit of the vehicle-mounted charger according to claim 10, wherein the difference comparison processing circuit comprises: an impedance matching circuit and a filter circuit; wherein:
the input end of the impedance matching circuit is used as the input end of the difference comparison processing circuit, and the output end of the impedance matching circuit is connected to the input end of the filter circuit;
and the output end of the filter circuit is used as the output end of the difference value comparison processing circuit.
12. The alternating current side insulation detection circuit of the vehicle-mounted charger according to claim 11, wherein the impedance matching circuit is an operational amplifier; wherein:
the non-inverting input end of the operational amplifier is used as the input end of the impedance matching circuit, the inverting input end of the operational amplifier is connected with the output end of the operational amplifier, and the connection point is used as the output end of the impedance matching circuit.
13. The alternating current side insulation detection circuit of the vehicle-mounted charger according to claim 11, wherein the filter circuit comprises: a first resistor and a first capacitor; wherein:
one end of the first resistor is used as the input end of the filter circuit;
the other end of the first resistor is connected with one end of the first capacitor, and a connection point is used as the output end of the filter circuit;
the other end of the first capacitor is connected with the vehicle body.
14. The alternating current side insulation detection circuit of the vehicle-mounted charger according to any one of claims 4 to 6, wherein the controller is any one of a micro control unit, a digital signal processor or a programmable gate array.
15. A vehicle-mounted charger is characterized in that the vehicle-mounted charger is a bidirectional vehicle-mounted charger or an all-in-one bidirectional vehicle-mounted power supply integrated module, and an alternating current side of the vehicle-mounted charger is provided with an alternating current side insulation detection circuit of the vehicle-mounted charger according to any one of claims 4 to 14.
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