CN115932514A - Insulation detection method and circuit - Google Patents
Insulation detection method and circuit Download PDFInfo
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- CN115932514A CN115932514A CN202211685543.2A CN202211685543A CN115932514A CN 115932514 A CN115932514 A CN 115932514A CN 202211685543 A CN202211685543 A CN 202211685543A CN 115932514 A CN115932514 A CN 115932514A
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Abstract
The invention provides an insulation detection method and circuit, and belongs to the technical field of insulation fault judgment. The method comprises the following steps: acquiring bus voltage, half bus voltage facing the ground and threshold voltage of current insulation equipment; and determining the fault of the insulating equipment according to the magnitude relation of the difference values between the half bus voltage and the threshold voltage and between the half bus voltage and the bus voltage and between the half bus voltage and the threshold voltage in continuous sampling. Through the technical scheme, the insulation detection method and the circuit provided by the invention can determine whether the insulation fault occurs at present through the direct size relationship between the half bus voltage and the threshold voltage, and the size relationship between the half bus voltage and the difference between the half bus voltage and the difference between the bus voltage and the threshold voltage, so that the insulation fault can be quickly judged.
Description
Technical Field
The invention relates to the technical field of insulation fault judgment, in particular to an insulation detection method and circuit.
Background
With the popularization of new energy vehicles and the popularization of renewable energy photovoltaic power generation, the three-phase inverter is fully applied in the two industries, the motor controller for the new energy vehicle and the front-stage power supply of the photovoltaic inverter for photovoltaic power generation are matched with the battery, and the battery has the possibility of liquid leakage; the output cable of the motor controller and the corresponding motor load also have the problems of skin breaking and abnormal insulation of the winding to the ground, so that the inverter is applied to the two fields, and insulation detection needs to be matched. At present, the battery end of the whole vehicle can be matched with an insulation detector detected by a small pulse injection method or an insulation detector detected by a bridge method as shown in fig. 1, the detection is limited by the limitation of detection topology and detection method, the real-time performance of detection is difficult to guarantee, the response time is basically about 10s, particularly, in order to solve the problem of EMI, an Y capacitor to the ground is added at the input end of a bus, and the detection precision and the response time of the insulation resistance value are influenced to different degrees by the capacitance value of the added Y capacitor. However, due to the existence of the Y capacitor of the inverter, when the bus or the output is abnormal to the ground, we need fast and accurate protection, otherwise, when a single-point or multi-point to ground short circuit occurs, a charge-discharge loop can be formed through the Y capacitor, because the magnitude of the loop current is determined by the loop impedance, when the ground short circuit occurs or the insulation resistance value is very low, the loop current value will be very large, at this time, the fault may be enlarged, if the fault is not timely responded, a fire disaster and other serious accidents are likely to occur, so it is imperative to fast and accurately detect the insulation abnormality.
Disclosure of Invention
The embodiment of the invention aims to provide an insulation detection method and circuit, which can quickly and accurately judge whether an insulation abnormal fault occurs.
In order to achieve the above object, an embodiment of the present invention provides an insulation detection method, including:
acquiring bus voltage, half bus voltage facing the ground and threshold voltage of current insulation equipment;
and determining the fault of the insulating equipment according to the magnitude relation of the difference values between the half bus voltage and the threshold voltage and between the half bus voltage and the bus voltage and between the half bus voltage and the threshold voltage in continuous sampling.
Optionally, the determining the fault of the insulating device according to the magnitude relationship between the half-bus voltage and the threshold voltage, and the half-bus voltage and the threshold voltage in the continuous sampling includes:
judging whether the half bus voltage sampled twice continuously is smaller than the threshold voltage in the same sampling period;
in the same sampling period, under the condition that the half bus voltage sampled continuously twice is smaller than the threshold voltage, judging whether the half bus voltage sampled continuously for preset times is smaller than the threshold voltage;
updating a first abnormal count value under the condition that the half bus voltage sampled for continuous preset times is judged to be smaller than the threshold voltage;
judging whether the first abnormal count value is greater than or equal to a preset first threshold value or not;
and under the condition that the first abnormal count value is judged to be larger than or equal to the first threshold value, determining that the insulation equipment has a direct current earth-facing abnormal fault.
Optionally, determining the fault of the insulating device according to the magnitude relationship of the difference between the half-bus voltage and the threshold voltage, and the difference between the half-bus voltage and the threshold voltage in the continuous sampling further includes:
and resetting a first abnormal count value under the condition that the half bus voltages sampled for the continuous preset times are not smaller than the threshold voltage.
Optionally, determining the fault of the insulating device according to the magnitude relationship between the half bus voltage and the threshold voltage and the difference between the half bus voltage and the threshold voltage in the continuous sampling further includes:
judging whether the half bus voltage sampled twice continuously is larger than the difference value between the bus voltage and the threshold voltage in the same sampling period;
in the same sampling period, under the condition that the half bus voltage sampled for two times continuously is larger than the difference value between the bus voltage and the threshold voltage, judging whether the half bus voltage sampled for the preset times continuously is larger than the difference value between the bus voltage and the threshold voltage;
updating a second abnormal count value under the condition that the half bus voltage sampled for continuous preset times is judged to be larger than the difference value between the bus voltage and the threshold voltage;
judging whether the second abnormal count value is greater than or equal to a preset second threshold value;
and under the condition that the second abnormal count value is judged to be larger than or equal to the second threshold value, determining that the direct-current negative ground abnormal fault occurs in the insulating equipment.
Optionally, determining the fault of the insulating device according to the magnitude relationship between the half bus voltage and the threshold voltage and the difference between the half bus voltage and the threshold voltage in the continuous sampling further includes:
and resetting a second abnormal count value under the condition that the half bus voltage sampled for the continuous preset times is judged to be not greater than the difference value between the bus voltage and the threshold voltage.
Optionally, determining the fault of the insulating device according to the magnitude relationship of the difference between the half-bus voltage and the threshold voltage, and the difference between the half-bus voltage and the threshold voltage in the continuous sampling further includes:
judging whether one of the half bus voltages sampled twice is larger than the difference value between the bus voltage and the threshold voltage and the other half bus voltage is smaller than the threshold voltage in the same sampling period;
in the same sampling period, judging whether one of the half bus voltages sampled twice is larger than the difference value between the bus voltage and the threshold voltage and the other half bus voltage is smaller than the threshold voltage or not under the condition that one of the half bus voltages sampled twice is larger than the difference value between the bus voltage and the threshold voltage and the other half bus voltage is smaller than the threshold voltage;
updating a third anomaly count value under the condition that one of the half bus voltages in every two times of continuous sampling is judged to be greater than the difference value between the bus voltage and the threshold voltage, and the other half bus voltage is smaller than the threshold voltage;
determining whether the third anomaly count value is greater than or equal to a third threshold value;
and determining that the insulation equipment has an AC-to-ground abnormal fault when the third anomaly count value is judged to be greater than or equal to a third threshold value.
Optionally, determining the fault of the insulating device according to the magnitude relationship between the half bus voltage and the threshold voltage and the difference between the half bus voltage and the threshold voltage in the continuous sampling further includes:
and resetting a third anomaly count value when judging that one of the half bus voltages at every two times in continuous sampling is not greater than the difference value between the bus voltage and the threshold voltage and the other half bus voltage is less than the threshold voltage.
In another aspect, the present invention also provides an insulation detection circuit, comprising:
one end of the first resistor is used for being connected to a positive phase line of a bus, and the other end of the first resistor is connected with a direct current power supply;
one end of the second resistor is connected with the other end of the first resistor, and the other end of the second resistor is used for being connected to a ground voltage;
one end of the first capacitor is connected with one end of the second resistor, and the other end of the first capacitor is connected with the other end of the second resistor;
one end of the third resistor is grounded, and the other end of the third resistor is connected with a direct-current power supply;
a positive-phase input end of the first operational amplifier is connected with one end of the first capacitor, and a negative-phase input end of the first operational amplifier is connected with the other end of the third resistor;
one end of the fourth resistor is connected with the inverting input end of the first operational amplifier;
one end of the fifth resistor is connected with the other end of the fourth resistor, and the other end of the fifth resistor is connected with the output end of the first operational amplifier;
one end of the second capacitor is connected with one end of the fourth resistor, and the other end of the second capacitor is connected with the other end of the fifth resistor;
one end of the sixth resistor is connected with the output end of the first operational amplifier;
one end of the third capacitor is connected with the other end of the sixth resistor, and the other end of the third capacitor is grounded;
one end of the seventh resistor is connected with one end of the third capacitor, and the other end of the seventh resistor is grounded;
a positive-phase input end of the second operational amplifier is connected with one end of the seventh resistor;
one end of the eighth resistor is connected to a ground voltage, and the other end of the eighth resistor is connected with the inverted input end of the second operational amplifier;
one end of the ninth resistor is connected with the inverting input end of the second operational amplifier, and the other end of the ninth resistor is connected with the output end of the second operational amplifier;
one end of the fourth capacitor is connected with one end of the ninth resistor, and the other end of the fourth capacitor is connected with the other end of the ninth resistor;
one end of the tenth resistor is connected with the output end of the second operational amplifier, and the other end of the tenth resistor is used for outputting half bus voltage;
a negative electrode of the first diode is connected with a direct current power supply, and a positive electrode of the first diode is connected with the other end of the tenth resistor;
one end of the fifth capacitor is connected with the anode of the first diode, and the other end of the fifth capacitor is grounded;
one end of the eleventh resistor is used for being connected with a negative phase line of the bus, and the other end of the eleventh resistor is connected to a direct-current power supply;
one end of the sixth capacitor is connected with the other end of the eleventh resistor;
one end of the twelfth resistor is connected with one end of the sixth capacitor;
one end of the thirteenth resistor is connected with the other end of the twelfth resistor, and the other end of the thirteenth resistor is connected with the other end of the sixth capacitor;
a positive-phase input end of the third operational amplifier is connected with one end of the sixth capacitor, and an output end of the third operational amplifier is connected with the other end of the sixth capacitor;
a fourteenth resistor, one end of which is connected to the other end of the sixth capacitor;
one end of the seventh capacitor is connected with the other end of the fourteenth resistor, and the other end of the seventh capacitor is grounded;
a fifteenth resistor, one end of which is connected with the other end of the fourteenth resistor, and the other end of which is grounded;
a positive-phase input end of the fourth operational amplifier is connected with one end of the fifteenth resistor;
one end of the sixteenth resistor is connected to a ground voltage, and the other end of the sixteenth resistor is connected with the inverted input end of the fourth operational amplifier;
one end of the seventeenth resistor is connected with the inverting input end of the fourth operational amplifier, and the other end of the seventeenth resistor is connected with the output end of the fourth operational amplifier;
one end of the eighth capacitor is connected with one end of the seventeenth resistor, and the other end of the eighth capacitor is connected with the other end of the seventeenth resistor;
one end of the eighteenth resistor is connected with the output end of the fourth operational amplifier, and the other end of the eighteenth resistor is used for outputting bus voltage;
the anode of the second diode is connected with the other end of the eighteenth resistor, and the cathode of the second diode is connected with a direct-current power supply;
and one end of the ninth capacitor is connected with the other end of the eighteenth resistor, and the other end of the ninth capacitor is grounded.
Optionally, the circuit further comprises a controller connected to the other end of the tenth resistor and the other end of the eighteenth resistor, for performing the method as described in any one of the above.
In yet another aspect, the invention also provides a computer readable storage medium having stored thereon instructions for reading by a machine to cause the machine to perform a method as described in any one of the above.
Through the technical scheme, the insulation detection method and the circuit provided by the invention determine whether the insulation fault occurs at present through the direct size relationship between the half-bus voltage and the threshold voltage and the size relationship between the half-bus voltage and the difference value between the bus voltage and the threshold voltage, so that the insulation fault can be rapidly judged.
Additional features and advantages of embodiments of the present invention will be described in the detailed description which follows.
Drawings
The accompanying drawings, which are included to provide a further understanding of the embodiments of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the embodiments of the invention and not to limit the embodiments of the invention. In the drawings:
FIG. 1 is an exemplary diagram of a conventional insulation detection circuit in the prior art;
FIG. 2 is a flow diagram of an insulation detection method according to one embodiment of the present invention;
FIG. 3 is a flow diagram of a method of determining a DC to ground fault according to one embodiment of the present invention;
FIG. 4 is a flow diagram of a method of determining a DC negative to ground fault according to one embodiment of the present invention;
FIG. 5 is a flow diagram of a method of determining an AC to ground fault according to one embodiment of the present invention;
fig. 6 is a circuit diagram of an insulation detection circuit according to an embodiment of the present invention.
Detailed Description
The following detailed description of embodiments of the invention refers to the accompanying drawings. It should be understood that the detailed description and specific examples, while indicating embodiments of the invention, are given by way of illustration and explanation only, not limitation.
Fig. 2 is a flow chart illustrating an insulation detection method according to an embodiment of the present invention. In this fig. 2, the method may include:
in step S10, acquiring a bus voltage, a half bus voltage directly facing the ground, and a threshold voltage of the current insulation device;
in step S11, a fault of the insulating device is determined according to the magnitude relationship of the difference between the half bus voltage and the threshold voltage, and the difference between the half bus voltage and the bus voltage, and the threshold voltage in the continuous sampling. In this embodiment, there may be two relationships between the half bus voltage and the threshold voltage, and the difference between the half bus voltage and the threshold voltage, specifically, the half bus voltage is smaller than the threshold voltage, and the half bus voltage is greater than the difference between the bus voltage and the threshold voltage. Based on the two magnitude relationships, various insulation faults can be determined.
Specifically, for the dc-to-ground abnormal fault, this step S11 may include steps as shown in fig. 3. In the fig. 3, the step S11 may further include the steps of:
in step S20, it is determined whether half bus voltages sampled twice consecutively are all smaller than the threshold voltage in the same sampling period;
in step S21, in the case that it is determined that half bus voltages sampled twice consecutively are smaller than the threshold voltage in the same sampling period, it is determined whether half bus voltages sampled for consecutive preset times are both smaller than the threshold voltage;
in step S22, under the condition that it is determined that the half-bus voltages sampled for the consecutive preset times are all smaller than the threshold voltage, updating a first abnormal count value;
in step S23, it is determined whether the first abnormal count value is greater than or equal to a preset first threshold value;
in step S24, in a case where it is determined that the first abnormal count value is greater than or equal to the first threshold value, it is determined that the insulating apparatus has an abnormal fault with direct current to ground;
in step S25, resetting a first abnormal count value when it is determined that the half-bus voltages sampled for the consecutive preset times are less than the threshold voltage;
in this step S25, in consideration of the judgment if the first threshold value set by the system itself is artificially experienced, the first threshold value used for judging the abnormal count value may deviate from the accurate value due to a change in the operating condition of the insulation apparatus itself during the actual operation. Thus, in one example of the invention, further adjustments may be made to the first threshold. Specifically, the adjustment may be to update the threshold value according to formula (1),
t 1 ＝t 1 -Number(x≥x 1 )， (1)
wherein, t 1 Is a first threshold value, number (x is more than or equal to x) 1 ) Before the DC ground fault is sent out, the first abnormal count value x is larger than a preset threshold value x 1 The number of times. And after the alarm of the direct current positive ground abnormal fault is given, the threshold value can be reset to the initial state again.
Specifically, for a dc negative ground fault, this step S11 may include steps as shown in fig. 4. In this fig. 4, the step S11 may further include the steps of:
in step S30, it is determined whether half bus voltages sampled twice consecutively are both greater than the difference between the bus voltage and the threshold voltage in the same sampling period;
in step S31, in the case that it is determined that the half bus voltages sampled twice consecutively are both greater than the difference between the bus voltage and the threshold voltage in the same sampling period, it is determined whether the half bus voltages sampled for the consecutive preset times are both greater than the difference between the bus voltage and the threshold voltage;
in step S32, updating a second abnormal count value when it is determined that the half-bus voltages sampled for the consecutive preset times are all greater than the difference between the bus voltage and the threshold voltage;
in step S33, it is determined whether the second abnormal count value is greater than or equal to a preset second threshold value;
in step S34, in the case that the second abnormal count value is judged to be greater than or equal to the second threshold value, it is determined that the direct-current negative ground abnormal fault occurs in the insulation device;
in step S35, in a case where it is determined that the half-bus voltages sampled for the consecutive preset times are not all larger than the difference between the bus voltage and the threshold voltage, the second abnormal count value is reset. In this step S35, in consideration of the judgment of human experience if the second threshold value set by the system itself is present, the second threshold value used for judging the abnormal count value may deviate from an accurate value due to a change in the operating condition of the insulation apparatus itself during actual operation. Thus, in one example of the invention, further adjustments may be made to the second threshold. Specifically, the adjustment may be to update the threshold value according to equation (2),
t 2 ＝t 2 -Number(x≥x 2 )， (2)
wherein, t 2 Is a second threshold value, number (x ≧ x) 2 ) Indicating that the second abnormal count value x is larger than the preset threshold value x before the direct current negative earth fault is sent 2 The number of times. And after the alarm of the DC negative earth fault is given out, the threshold value can be reset to the initial state again.
Specifically, for the ac-to-ground abnormal fault, this step S11 may include steps as shown in fig. 5. In the fig. 5, the step S11 may further include the steps of:
in step S40, it is determined whether one of the half bus voltages sampled twice in the same sampling period is greater than the difference between the bus voltage and the threshold voltage, and the other is less than the threshold voltage;
in step S41, in the same sampling period, when it is determined that one of the half bus voltages sampled twice adjacent to each other is greater than the difference between the bus voltage and the threshold voltage, and the other is less than the threshold voltage, it is determined whether one of the half bus voltages sampled twice in consecutive sampling is greater than the difference between the bus voltage and the threshold voltage, and the other is less than the threshold voltage;
in step S42, when it is determined that one of the half bus voltages at every two times in the continuous sampling is greater than the difference between the bus voltage and the threshold voltage and the other half bus voltage is less than the threshold voltage, updating a third anomaly count value;
in step S43, it is determined whether the third anomaly count value is greater than or equal to a third threshold value;
in step S44, in a case where it is determined that the third anomaly count value is greater than or equal to the third threshold value, it is determined that an ac-to-ground abnormal fault has occurred in the insulation apparatus.
In step S45, when it is determined that there is no half bus voltage for every two times in consecutive sampling, one of the half bus voltages is greater than the difference between the bus voltage and the threshold voltage, and the other half bus voltage is less than the threshold voltage, the third anomaly count value is reset. In this step S45, in consideration of the judgment of human experience if the third threshold value set by the system itself exists, the third threshold value used for judging the abnormal count value may deviate from an accurate value due to a change in the operating condition of the insulation apparatus itself during actual operation. Thus, in one example of the invention, the third threshold may be further adjusted. Specifically, the adjustment may be to update the threshold value according to equation (3),
t 3 ＝t 3 -Number(x≥x 3 )， (3)
wherein, t 3 Is a third threshold value, number (x ≧ x) 3 ) Before sending out the AC earth fault, the second abnormal count value x is larger than the preset threshold value x 3 The number of times. And after the alarm of the abnormal fault of the alternating current to the ground is given, the threshold value can be reset to the initial state again.
On the other hand, in order to obtain the bus voltage and the half bus voltage, the invention also provides an insulation detection circuit. The structure of the circuit may be as shown in fig. 6. In fig. 6, the circuit may include first to eighteenth resistors R1 to R18, first to ninth capacitors C1 to C9, first to fourth operational amplifiers U1 to U4, a first diode D1, and a second diode D2.
Specifically, in the circuit shown in fig. 6, one end of the first resistor R1 may be used to be connected to a positive phase line (DC +) of the bus, and the other end of the first resistor R1 may be connected to a direct current power supply. Wherein, since the first resistor R1 is a positive phase line directly connected to the bus, the first resistor R1 may be a series resistor formed by connecting a plurality of resistors in series in consideration of a high voltage on the positive phase line, thereby facilitating a reasonable voltage drop. One end of the second resistor R2 may be connected to the other end of the first resistor R1, and the other end of the second resistor R2 may be used to be connected to a ground voltage. One end of the first capacitor C1 may be connected to one end of the second resistor R2, and the other end of the first capacitor C1 may be connected to the other end of the second resistor R2. One end of the third resistor R3 may be grounded, and the other end of the third resistor R3 may be connected to a dc power supply. The non-inverting input terminal of the first operational amplifier U1 may be connected to one end of the first capacitor C1, and the inverting input terminal of the first operational amplifier U1 may be connected to the other end of the third resistor R3. One end of the fourth resistor R4 may be connected to the inverting input terminal of the first operational amplifier U1. One end of the fifth resistor R5 may be connected to the other end of the fourth resistor R4, and the other end of the fifth resistor R5 may be connected to the output end of the first operational amplifier U1. One end of the second capacitor C2 may be connected to one end of the fourth resistor R4, and the other end of the second capacitor C2 may be connected to the other end of the fifth resistor R5. One end of the sixth resistor R6 may be connected to the output end of the first operational amplifier U1. One end of the third capacitor C3 may be connected to the other end of the sixth resistor R6, and the other end of the third capacitor C3 may be grounded. One end of the seventh resistor R7 may be connected to one end of the third capacitor C3, and the other end of the seventh resistor R7 may be grounded. The non-inverting input terminal of the second operational amplifier U1 may be connected to one end of the seventh resistor R7. One end of the eighth resistor R8 may be connected to a ground voltage, and the other end of the eighth resistor R8 may be connected to the inverting input terminal of the second operational amplifier U2. One end of the ninth resistor R9 may be connected to the inverting input terminal of the second operational amplifier U2, and the other end of the ninth resistor R9 may be connected to the output terminal of the second operational amplifier U2. One end of the fourth capacitor C4 may be connected to one end of the ninth resistor R9, and the other end of the fourth capacitor C4 may be connected to the other end of the ninth resistor R9. One end of the tenth resistor R10 may be connected to the output terminal of the second operational amplifier U2, and the other end of the tenth resistor R10 may be configured to output the HALF-bus voltage HALF _ UDC. A cathode of the first diode D1 may be connected to a dc power source, and an anode of the first diode D1 may be connected to the other end of the tenth resistor R10. One end of the fifth capacitor C5 may be connected to the anode of the first diode D1, and the other end of the fifth capacitor C5 is grounded. One end of the eleventh resistor R11 may be used for connection with the negative phase line of the bus bar, and the other end of the eleventh resistor R11 is connected to the dc power supply. One end of the sixth capacitor C6 may be connected to the other end of the eleventh resistor R11. One end of the twelfth resistor R12 may be connected to one end of the sixth capacitor C6. One end of the thirteenth resistor R13 may be connected to the other end of the twelfth resistor R12, and the other end of the thirteenth resistor R13 is connected to the other end of the sixth capacitor C6. The inverting input terminal of the third operational amplifier U1 may be connected to the non-inverting input terminal of the first operational amplifier U1, the non-inverting input terminal of the third operational amplifier U1 may be connected to one end of the sixth capacitor C6, and the output terminal of the third operational amplifier U1 may be connected to the other end of the sixth capacitor C6. One end of the fourteenth resistor R14 is connected to the other end of the sixth capacitor C6. One end of the seventh capacitor C7 may be connected to the other end of the fourteenth resistor R14, and the other end of the seventh capacitor C7 may be grounded. One end of the fifteenth resistor R15 may be connected to the other end of the fourteenth resistor R14, and the other end of the fifteenth resistor R15 may be grounded. A non-inverting input terminal of the fourth operational amplifier U4 may be connected to one terminal of the fifteenth resistor R15. One end of the sixteenth resistor R16 may be connected to the ground voltage, and the other end of the sixteenth resistor R16 is connected to the inverting input terminal of the fourth operational amplifier U4. One end of the seventeenth resistor R17 may be connected to the inverting input terminal of the fourth operational amplifier U4, and the other end of the seventeenth resistor R17 may be connected to the output terminal of the fourth operational amplifier U4. One end of the eighth capacitor C8 may be connected to one end of the seventeenth resistor R17, and the other end of the eighth capacitor C8 may be connected to the other end of the seventeenth resistor R17. One end of the eighteenth resistor R18 may be connected to the output end of the fourth operational amplifier U4, and the other end of the eighteenth resistor R18 may be used to output the bus voltage UDC. An anode of the second diode D2 may be connected to the other end of the eighteenth resistor, and a cathode of the second diode D2 may be connected to a dc power supply. One end of the ninth capacitor C9 may be connected to the other end of the eighteenth resistor R18, and the other end of the ninth capacitor C9 may be grounded.
Optionally, the circuit further comprises a controller connected to the other end of the tenth resistor and the other end of the eighteenth resistor for performing the method as shown in fig. 2 to 5.
Under normal conditions, half bus voltage is half of bus voltage theoretically, but due to the fact that the positive and negative insulation resistance to ground is asymmetric, if the half bus voltage falls within the interval of the threshold voltage and the difference value between the threshold voltage and the bus voltage, the half bus voltage can be judged to be not in an insulation abnormal fault at the moment, a fault counting value is not triggered, and the half bus voltage is always in a normal state. The counting is occasionally triggered by mistake, and the insulation abnormal fault is not triggered by mistake and is judged to be normal as long as the continuous counting does not occur and reaches a preset threshold (for example, 200 times).
In the abnormal condition, firstly, the direct current insulation abnormality is described, when the direct current is in the state of insulation abnormality or even short circuit, the detection value of the bus voltage UDC is not influenced, but the value of the HALF bus voltage HALF _ UDC of which the direct current is over the ground is far deviated from the HALF of the bus voltage. It can be seen from the circuit diagram that when the dc current is experiencing an insulation anomaly, the two sampling values in each switching period of the half-bus voltage with the dc current facing the ground will be very low or even 0, i.e. the sampling voltage will be lower than the threshold voltage.
When the direct current negative voltage has insulation abnormity or even short circuit, the detection value of the bus voltage UDC is not influenced, but the value of the HALF bus voltage HALF _ UDC of which the direct current is over the ground is far deviated from the HALF of the bus voltage. As can be seen from the circuit diagram, when the insulation abnormality occurs in the dc negative, the two sampled values in each switching cycle of the HALF bus voltage HALF _ UDC with the dc positive to ground at the time are both greater than the difference between the bus power supply and the threshold voltage, so that it can be determined that the dc negative to ground fault occurs at the time.
When an alternating current ground fault occurs, the fault is characterized in that the insulation abnormality does not occur in the direct current positive or direct current negative, and the insulation abnormality occurs in one phase of the output such as the U/V/W three-phase. In this embodiment, U-phase insulation abnormality may be taken as an example. When a U-phase insulation abnormality (ground fault) occurs, the detection value of the bus voltage UDC remains unaffected, but the value of the HALF-bus voltage HALF _ UDC whose direct current is directly opposite to the ground is far from HALF the bus voltage. As can be seen from the circuit diagram of fig. 6, when the U-phase insulation is abnormal, the value of the HALF-bus voltage HALF _ UDC directly facing the ground varies with the on-off state of the switching tube corresponding to the U-phase bridge.
When the upper bridge of the U phase is conducted, the sampling value of the HALF bus voltage HALF _ UDC with direct current facing the ground falls in a region lower than a set threshold voltage;
when the U-phase upper bridge is switched off, two operating states are experienced: firstly, the upper and lower bridge IGBTs are in a turn-off state, the sampling value of the HALF bus voltage HALF _ UDC is related to the current direction at the moment before the upper bridge IGBT body is turned off, if the current flows through the freewheeling diode of the IGBT before the upper bridge IGBT is turned off, the current continues to flow through the freewheeling diode of the upper bridge IGBT after the upper bridge IGBT body is turned off, and at the moment, the sampling value of the HALF bus voltage HALF _ UDC is continuously lower than the range of the set threshold voltage; if the current flows through the body of the upper bridge IGBT before being turned off, the current flows through the U-phase lower bridge freewheeling diode after being turned off, and at the moment, the sampling value of the HALF bus voltage HALF _ UDC falls within the range of the difference value of the bus voltage minus the threshold voltage. And then, in the state that the lower bridge IGBT body is conducted, the sampling value of the HALF bus voltage HALF _ UDC is in the range larger than the difference value obtained by subtracting the threshold voltage from the bus voltage.
Because the upper bridge and the lower bridge are complementarily conducted and the sampling time is selected at the central point of the conduction or the turn-off of the switch, the turn-off state of the IGBT of the upper bridge and the IGBT of the lower bridge is not collected. Therefore, the two sampling values in one switching cycle are abnormal, namely, the HALF bus voltage HALF _ UDC _ AD directly facing the ground is smaller than Uth when the U-phase upper bridge is switched on, and the HALF bus voltage HALF _ UDC _ AD directly facing the ground is larger than Udc-Uth when the U-phase upper bridge is switched off.
According to the three insulation abnormal conditions and the difference of the HALF bus voltage HALF _ UDC sampling values under the corresponding working conditions, the fault counting value and the corresponding threshold value are set by the method shown in the figures 2 to 5, filtering is realized by the technical threshold value, and the detection accuracy is ensured.
In yet another aspect, the present invention also provides a computer-readable storage medium storing instructions for reading by a machine to cause the machine to perform the method as illustrated in fig. 2 to 5.
Through the technical scheme, the insulation detection method and the circuit provided by the invention determine whether the insulation fault occurs at present through the direct size relationship between the half-bus voltage and the threshold voltage and the size relationship between the half-bus voltage and the difference value between the bus voltage and the threshold voltage, so that the insulation fault can be rapidly judged.
As will be appreciated by one skilled in the art, embodiments of the present application may be provided as a method, system, or computer program product. Accordingly, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present application may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, and the like) having computer-usable program code embodied therein.
The present application is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the application. It will be understood that each flow and/or block of the flow diagrams and/or block diagrams, and combinations of flows and/or blocks in the flow diagrams and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
In a typical configuration, a computing device includes one or more processors (CPUs), input/output interfaces, network interfaces, and memory.
The memory may include forms of volatile memory in a computer readable medium, random Access Memory (RAM) and/or non-volatile memory, such as Read Only Memory (ROM) or flash memory (flash RAM). The memory is an example of a computer-readable medium.
Computer-readable media, including both permanent and non-permanent, removable and non-removable media, may implement the information storage by any method or technology. The information may be computer readable instructions, data structures, modules of a program, or other data. Examples of computer storage media include, but are not limited to, phase change memory (PRAM), static Random Access Memory (SRAM), dynamic Random Access Memory (DRAM), other types of Random Access Memory (RAM), read Only Memory (ROM), electrically Erasable Programmable Read Only Memory (EEPROM), flash memory or other memory technology, compact disc read only memory (CD-ROM), digital Versatile Discs (DVD) or other optical storage, magnetic cassettes, magnetic tape magnetic disk storage or other magnetic storage devices, or any other non-transmission medium that can be used to store information that can be accessed by a computing device. As defined herein, a computer readable medium does not include a transitory computer readable medium such as a modulated data signal and a carrier wave.
It should also be noted that 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 a … …" does not exclude the presence of another identical element in a process, method, article, or apparatus that comprises the element.
The above are merely examples of the present application and are not intended to limit the present application. Various modifications and changes may occur to those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the scope of the claims of the present application.
Claims (10)
1. An insulation detection method, characterized in that the method comprises:
acquiring bus voltage, half bus voltage over the ground and threshold voltage of current insulation equipment;
and determining the fault of the insulating equipment according to the magnitude relation of the difference values between the half bus voltage and the threshold voltage and between the half bus voltage and the bus voltage and between the half bus voltage and the threshold voltage in continuous sampling.
2. The method of claim 1, wherein determining the fault of the insulated device based on the magnitude of the difference between the half bus voltage and the threshold voltage and the half bus voltage and the threshold voltage in successive samples comprises:
judging whether the half bus voltage sampled continuously twice is smaller than the threshold voltage in the same sampling period;
in the same sampling period, under the condition that the half bus voltage sampled for two times continuously is smaller than the threshold voltage, judging whether the half bus voltage sampled for the preset times continuously is smaller than the threshold voltage;
updating a first abnormal count value under the condition that the half bus voltages sampled for the continuous preset times are all smaller than the threshold voltage;
judging whether the first abnormal count value is greater than or equal to a preset first threshold value or not;
and under the condition that the first abnormal count value is judged to be larger than or equal to the first threshold value, determining that the direct current positive earth abnormal fault occurs in the insulating equipment.
3. The method of claim 2, wherein determining the fault of the insulated device based on the magnitude of the difference between the half bus voltage and the threshold voltage and the half bus voltage and the threshold voltage in successive samples further comprises:
and resetting a first abnormal count value under the condition that the half bus voltages sampled for the continuous preset times are not smaller than the threshold voltage.
4. The method of claim 1, wherein determining the fault in the insulated device based on the magnitude of the difference between the half bus voltage and the threshold voltage, and the half bus voltage and the bus voltage and threshold voltage in successive samples further comprises:
judging whether the half bus voltage sampled twice continuously is larger than the difference value between the bus voltage and the threshold voltage in the same sampling period;
in the same sampling period, under the condition that the half bus voltage sampled for two times continuously is larger than the difference value between the bus voltage and the threshold voltage, judging whether the half bus voltage sampled for the preset times continuously is larger than the difference value between the bus voltage and the threshold voltage;
updating a second abnormal count value under the condition that the half bus voltage sampled by continuous preset times is judged to be larger than the difference value between the bus voltage and the threshold voltage;
judging whether the second abnormal count value is greater than or equal to a preset second threshold value;
and under the condition that the second abnormal count value is judged to be larger than or equal to the second threshold value, determining that the direct-current negative ground abnormal fault occurs in the insulating equipment.
5. The method of claim 4, wherein determining the fault of the insulated device based on the magnitude of the difference between the half bus voltage and the threshold voltage and the half bus voltage and the threshold voltage in successive samples further comprises:
and resetting a second abnormal count value under the condition that the half bus voltage sampled for the continuous preset times is judged to be not greater than the difference value between the bus voltage and the threshold voltage.
6. The method of claim 1, wherein determining the fault in the insulated apparatus based on the magnitude relationship based on the difference between the half bus voltage and the threshold voltage, and the half bus voltage and the bus voltage and threshold voltage in successive samples further comprises:
judging whether one of the half bus voltages sampled twice is larger than the difference value between the bus voltage and the threshold voltage and the other half bus voltage is smaller than the threshold voltage in the same sampling period;
in the same sampling period, judging whether one of the half bus voltages sampled twice is larger than the difference value between the bus voltage and the threshold voltage and the other half bus voltage is smaller than the threshold voltage or not under the condition that one of the half bus voltages sampled twice is larger than the difference value between the bus voltage and the threshold voltage and the other half bus voltage is smaller than the threshold voltage;
updating a third anomaly count value under the condition that one of the half bus voltages in every two times of continuous sampling is judged to be greater than the difference value between the bus voltage and the threshold voltage, and the other half bus voltage is smaller than the threshold voltage;
determining whether the third anomaly count value is greater than or equal to a third threshold value;
and determining that the insulation equipment has an AC-to-ground abnormal fault when the third anomaly count value is judged to be greater than or equal to a third threshold value.
7. The method of claim 6, wherein determining the fault in the insulated device based on the magnitude of the difference between the half bus voltage and the threshold voltage, and the half bus voltage and the bus voltage and threshold voltage in successive samples further comprises:
and resetting a third anomaly count value when judging that one of the half bus voltages at every two times in continuous sampling is not greater than the difference value between the bus voltage and the threshold voltage and the other half bus voltage is less than the threshold voltage.
8. An insulation detection circuit, the circuit comprising:
one end of the first resistor is used for being connected to a positive phase line of a bus, and the other end of the first resistor is connected with a direct current power supply;
one end of the second resistor is connected with the other end of the first resistor, and the other end of the second resistor is used for being connected to a ground voltage;
one end of the first capacitor is connected with one end of the second resistor, and the other end of the first capacitor is connected with the other end of the second resistor;
one end of the third resistor is grounded, and the other end of the third resistor is connected with a direct-current power supply;
a positive-phase input end of the first operational amplifier is connected with one end of the first capacitor, and a negative-phase input end of the first operational amplifier is connected with the other end of the third resistor;
one end of the fourth resistor is connected with the inverting input end of the first operational amplifier;
one end of the fifth resistor is connected with the other end of the fourth resistor, and the other end of the fifth resistor is connected with the output end of the first operational amplifier;
one end of the second capacitor is connected with one end of the fourth resistor, and the other end of the second capacitor is connected with the other end of the fifth resistor;
one end of the sixth resistor is connected with the output end of the first operational amplifier;
one end of the third capacitor is connected with the other end of the sixth resistor, and the other end of the third capacitor is grounded;
one end of the seventh resistor is connected with one end of the third capacitor, and the other end of the seventh resistor is grounded;
a positive-phase input end of the second operational amplifier is connected with one end of the seventh resistor;
one end of the eighth resistor is connected to a ground voltage, and the other end of the eighth resistor is connected with the inverted input end of the second operational amplifier;
one end of the ninth resistor is connected with the inverting input end of the second operational amplifier, and the other end of the ninth resistor is connected with the output end of the second operational amplifier;
one end of the fourth capacitor is connected with one end of the ninth resistor, and the other end of the fourth capacitor is connected with the other end of the ninth resistor;
one end of the tenth resistor is connected with the output end of the second operational amplifier, and the other end of the tenth resistor is used for outputting half bus voltage;
a negative electrode of the first diode is connected with a direct current power supply, and a positive electrode of the first diode is connected with the other end of the tenth resistor;
one end of the fifth capacitor is connected with the anode of the first diode, and the other end of the fifth capacitor is grounded;
one end of the eleventh resistor is used for being connected with a negative phase line of the bus, and the other end of the eleventh resistor is connected to a direct-current power supply;
one end of the sixth capacitor is connected with the other end of the eleventh resistor;
one end of the twelfth resistor is connected with one end of the sixth capacitor;
one end of the thirteenth resistor is connected with the other end of the twelfth resistor, and the other end of the thirteenth resistor is connected with the other end of the sixth capacitor;
a positive-phase input end of the third operational amplifier is connected with one end of the sixth capacitor, and an output end of the third operational amplifier is connected with the other end of the sixth capacitor;
a fourteenth resistor, one end of which is connected to the other end of the sixth capacitor;
one end of the seventh capacitor is connected with the other end of the fourteenth resistor, and the other end of the seventh capacitor is grounded;
a fifteenth resistor, one end of which is connected with the other end of the fourteenth resistor, and the other end of which is grounded;
a positive-phase input end of the fourth operational amplifier is connected with one end of the fifteenth resistor;
one end of the sixteenth resistor is connected to a ground voltage, and the other end of the sixteenth resistor is connected with the inverted input end of the fourth operational amplifier;
one end of the seventeenth resistor is connected with the inverting input end of the fourth operational amplifier, and the other end of the seventeenth resistor is connected with the output end of the fourth operational amplifier;
one end of the eighth capacitor is connected with one end of the seventeenth resistor, and the other end of the eighth capacitor is connected with the other end of the seventeenth resistor;
one end of the eighteenth resistor is connected with the output end of the fourth operational amplifier, and the other end of the eighteenth resistor is used for outputting bus voltage;
the anode of the second diode is connected with the other end of the eighteenth resistor, and the cathode of the second diode is connected with a direct-current power supply;
and one end of the ninth capacitor is connected with the other end of the eighteenth resistor, and the other end of the ninth capacitor is grounded.
9. The circuit of claim 8, further comprising a controller connected to the other end of the tenth resistor and the other end of the eighteenth resistor for performing the method of any of claims 1-7.
10. A computer-readable storage medium having stored thereon instructions for reading by a machine to cause the machine to perform the method of any one of claims 1 to 7.
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| CN202211685543.2A CN115932514A (en) | 2022-12-27 | 2022-12-27 | Insulation detection method and circuit |
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| CN202211685543.2A CN115932514A (en) | 2022-12-27 | 2022-12-27 | Insulation detection method and circuit |
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