JP2012173053A - Electric leak detecting device and method for the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electric leak detecting device and an electric leak detecting method enabling electric leaks to be detected efficiently with a small number of components.SOLUTION: A first resistance 11a, a second resistance 11b and a third resistance 11c are connected in series between the P pole and the N pole of a high voltage DC power source 1; the high voltage DC power source 1 is actuated to apply voltage to detect the input voltage of an inverter 2 and, at the same time, the end-to-end voltage difference of the third resistance 11c in this state as a leak detecting voltage, deteriorations in insulation at the P pole and N pole of the high voltage DC power source 1 are detected on the basis of the detected leak detecting voltage and the inverter input voltage to detect deteriorations in insulation on the transmission route of three-phase AC power on the basis of the leak detecting voltage and the inverter input voltage when any one of the lower arms of the inverter 2 is placed in an ON state.

Description

  The present invention relates to a leakage detection device and a method thereof.

  BACKGROUND ART An electric compressor for a vehicle and an inverter device for a vehicle driven by a high voltage (for example, a 150V system, a 300V system, a 600V system, etc.) are composed of a battery and a power supply circuit that are insulated from a vehicle chassis. In general, the electrical equipment for a vehicle is driven by a battery of 12V system or 24V system, and its N pole side is connected to the chassis.

  2. Description of the Related Art Conventionally, a leakage detection device that detects a decrease in insulation in the U, V, and W phases of a motor connected to a P-pole and an N-pole of a high-voltage power supply and a vehicle inverter has been proposed. For example, Patent Document 1 discloses a high-voltage DC power source mounted on an electric vehicle or a train, two detection resistors connected in series between the positive and negative sides of the high-voltage DC power source, A switch that grounds one end of the resistor to the body ground.By switching the switch, the detection resistors are sequentially grounded to the body ground, and the detection voltages generated at the respective detection resistors at that time are measured. A leakage detection device that detects leakage and estimates a leakage location by performing comparative calculation is disclosed.

Japanese Patent Laid-Open No. 6-153301 (FIG. 1)

  However, in the leakage detection method based on resistance partial pressure as described above, it is necessary to measure the voltage across the detection resistor attached to the location where leakage is detected. Therefore, if it is attempted to detect not only the P-pole and N-pole of the high-voltage power supply but also the insulation drop occurring in the U, V, and W phases of the motor connected to the vehicle inverter, the number of parts increases, the cost increases, Increase in size and complexity of processing.

  The present invention has been made in view of such circumstances, and it is an object of the present invention to provide a leakage detection apparatus and method that can efficiently detect a leakage with a small number of parts.

In order to solve the above problems, the present invention employs the following means.
The present invention relates to a system comprising a DC power supply, an inverter that converts DC power supplied from the DC power supply into three-phase AC power, and a motor that is supplied with the three-phase AC power output from the inverter. A leakage detecting device for detecting insulation deterioration of the P and N poles of the DC power supply and insulation deterioration in the transmission path of the three-phase AC power, wherein one end is connected to the P pole of the DC power supply; One end connected to the other end of the first resistor and the second resistor connected to the frame ground; one end connected to the other end of the second resistor; the other end connected to the N pole of the DC power supply A third resistor connected; first voltage detecting means for detecting a voltage across the third resistor as a leakage detection voltage; second voltage detecting means for detecting an inverter input voltage; and processing means. means Insulation deterioration of the P pole and the N pole of the DC power supply is detected using the leakage detection voltage and the inverter input voltage when the upper arm and the lower arm of the inverter are turned off. Provided is a leakage detection device that detects insulation deterioration in a transmission path of the three-phase AC power based on the leakage detection voltage and the inverter input voltage when any one is turned on.

According to the leakage detecting device, the first resistor, the second resistor, and the third resistor are connected in series between the P pole and the N pole of the DC power supply, and the frame is formed between the first resistor and the second resistor. Connect to ground. In the leakage detection, the inverter input voltage is detected by the second voltage detection means, and all the arms of the inverter are turned off and a voltage is applied from the DC power supply. In this state, the first voltage detection means detects the third resistor. Both-end voltage is detected as a leakage detection voltage. The leakage detection voltage and the inverter input voltage detected by the second voltage detection means are input to the processing means, and the processing means detects insulation deterioration of the P and N poles of the DC power supply using the leakage detection voltage. Subsequently, the lower arm of any one of the inverters is turned on, and the leakage detection voltage at this time is detected by the first voltage detection means, and the processing means uses the leakage detection voltage and the inverter input voltage to detect 3 Insulation deterioration is detected in the phase AC power transmission path.
As described above, according to the leakage detection device of the present invention, by detecting the voltage across the third resistor, the insulation deterioration of the P-pole and N-pole of the DC power supply and the transmission path of the three-phase AC power can be reduced. It is possible to detect the leakage, and the leakage can be detected efficiently with a small number of parts.

  In the leakage detection device, the processing means includes an insulation resistance connecting the P pole of the DC power supply and the frame ground, a relationship between the leakage detection voltage and the inverter input voltage, and an N pole of the DC power supply and the frame ground. The relationship between the insulation resistance that connects the ground, the leakage detection voltage, and the inverter input voltage, and the relationship between the insulation resistance that connects the three-phase AC power transmission line and the frame ground, the leakage detection voltage, and the inverter input voltage Each of the insulation resistances based on the information, the leakage detection voltage detected by the first voltage detection means, and the inverter input voltage detected by the second voltage detection means. The leakage current may be detected based on the obtained insulation resistance value.

  According to such a configuration, the information indicating the relationship among each insulation resistance, leakage detection voltage, and inverter input voltage is stored in advance, so by using this information, the resistance of the insulation resistance can be determined from the leakage detection voltage. The value can be easily determined.

  In the leakage detection device, the processing means detects an insulation deterioration of the P pole of the DC power supply when the leakage detection voltage is equal to or higher than a first threshold determined by the inverter input voltage, and the leakage detection voltage is When it becomes less than a second threshold value determined by the inverter input voltage, insulation deterioration in the N pole of the DC power supply or the transmission path of the three-phase AC power may be detected.

  According to such a configuration, since the leakage is detected by increasing or decreasing the leakage detection voltage, it is possible to save the trouble of obtaining the resistance value of each insulation resistance from the leakage detection voltage and to detect the leakage by a simple process.

  In the leakage detection device, at least one of the first resistor, the second resistor, and the third resistor has a variable resistance value, and the processing means includes the first resistor, the second resistor, and the like. And at least one of the third resistors is changed, and the first voltage detecting means is a combination of the first resistor, the second resistor, and the third resistor having different voltage dividing ratios. The leakage detection voltage is detected at least twice, and the processing means is based on at least two leakage detection voltages detected by the first voltage detection means and the inverter input voltage detected by the second voltage detection means. Thus, it is possible to detect insulation deterioration of the P pole and the N pole of the DC power supply.

  According to such a configuration, the leakage detection voltage is detected at least twice by changing the resistance value of at least one of the first resistance, the second resistance, and the third resistance, and two or more leakage detection voltages and Since the insulation deterioration of the P pole and the N pole of the DC power supply is detected based on the inverter input voltage detected by the second voltage detection means, even when the insulation deterioration occurs in both the P pole and the N pole of the DC power supply. These insulation deteriorations can be detected.

  The present invention relates to a system comprising a DC power supply, an inverter that converts DC power supplied from the DC power supply into three-phase AC power, and a motor that is supplied with the three-phase AC power output from the inverter. A leakage detection method for detecting insulation deterioration of the P and N poles of the DC power supply and insulation deterioration in the transmission path of the three-phase AC power, the first resistor having one end connected to the P pole of the DC power supply One end connected to the other end of the first resistor and the second resistor connected to the frame ground; one end connected to the other end of the second resistor; the other end connected to the N pole of the DC power supply The connected third resistor is connected between the P pole and the N pole of the DC power supply, and the DC power supply is operated to apply a voltage to detect the inverter input voltage. Three Is detected as a leakage detection voltage, and based on the detected leakage detection voltage and the inverter input voltage, an insulation deterioration of the P pole and the N pole of the DC power supply is detected, and one of the lower arms of the inverter is detected. A leakage detection method is provided for detecting insulation deterioration in a transmission path of the three-phase AC power based on the leakage detection voltage and the inverter input voltage when one is turned on.

  In the present invention, when the DC power source is a high-voltage power source mounted on a vehicle and the motor is a motor used in an electric compressor included in an in-vehicle air conditioner, Provided is an electric leakage countermeasure method that implements at least one of starting / stopping a higher component, shutting off a high-voltage system of an entire vehicle, and notifying a vehicle crew when an insulation deterioration of a P pole or an N pole is detected.

  By taking such measures, the progress of insulation deterioration can be prevented, and damage due to electric leakage can be minimized.

  In the present invention, when the DC power source is a high-voltage power source mounted on a vehicle and the motor is a motor used in an electric compressor included in an in-vehicle air conditioner, When an insulation deterioration of the P pole or the N pole or an insulation deterioration in any of the transmission paths of the three-phase AC power is detected, the operation command to the electric compressor is stopped, the high voltage power to the electric compressor is cut off, Provided is a leakage countermeasure method that implements at least one of cutting off a high-voltage system of an entire vehicle and notifying leakage of electricity to a vehicle crew.

  By taking such measures, the progress of insulation deterioration can be prevented, and damage due to electric leakage can be minimized.

  According to the present invention, there is an effect that leakage can be detected efficiently with a small number of parts.

It is the figure which showed schematic structure of the leak detection apparatus which concerns on 1st Embodiment of this invention. It is the figure which showed the equivalent circuit at the time of making an insulation resistance, a leakage detection resistance, and a high voltage DC power supply into FIG. 1 as an element. In the equivalent circuit shown in FIG. 2, it is the figure which showed the flow of an electric current when insulation degradation has not arisen in the P pole and N pole of a high voltage | pressure DC power supply. In the equivalent circuit shown in FIG. 2, it is the figure which showed the flow of an electric current when insulation degradation generate | occur | produced only in the P pole of a high voltage DC power supply. In the equivalent circuit shown in FIG. 2, it is the figure which showed the flow of an electric current when insulation degradation generate | occur | produced only in the N pole of a high voltage DC power supply. An example of the characteristic diagram which showed the relationship between the leakage detection voltage and the resistance value of the insulation resistance of the P pole and N pole of a high voltage DC power supply is shown. In FIG. 1, it is the figure explaining the case where the insulation degradation of the transmission line of three-phase alternating current power is detected. It is the figure which showed the equivalent circuit in the case of detecting the insulation degradation of the transmission line of three-phase alternating current power. It is the flowchart which showed the procedure of the earth-leakage detection which concerns on 1st Embodiment of this invention. It is the figure which showed schematic structure of the leak detection apparatus which concerns on 2nd Embodiment of this invention. An example of the characteristic diagram which showed the relationship between the leakage detection voltage when opening a 1st resistance, and the resistance value of the P pole of a high voltage | pressure DC power supply, and the insulation resistance of a N pole is shown. It is the figure shown about the specific means which makes resistance value of 1st resistance variable. It is the flowchart which showed the procedure of the earth-leakage detection which concerns on 2nd Embodiment of this invention. It is the figure which each showed the relationship between the leakage detection voltage and the resistance value of insulation resistance.

[First Embodiment]
Hereinafter, a leakage detection apparatus and method according to a first embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a diagram illustrating a schematic configuration of a leakage detection apparatus according to the present embodiment. As shown in FIG. 1, a leakage detection device 10 according to the present embodiment includes an inverter that converts DC power supplied from the high-voltage DC power source 1 and the high-voltage DC power source 1 into three-phase AC power composed of U, V, and W phases. 2. Applied to an in-vehicle system including a motor 3 to which U, V, and W phase three-phase AC power output from the inverter 2 is supplied, and leakage and U generated in the P and N poles of the high-voltage DC power supply 1 , V, W phase is a device for detecting leakage in a total of five locations in each phase. The motor 3 is, for example, an electric compressor motor included in an in-vehicle air conditioner.

The leakage detection device 10 includes a voltage dividing resistor 11 connected between the P pole and the N pole of the high-voltage DC power supply 1. The voltage dividing resistor 11 includes a first resistor 11a, a second resistor 11b, and a third resistor 11c connected in series. One end of the first resistor 11a is connected to the P pole of the high-voltage DC power supply 1 and the other end is connected to one end of the second resistor. One end of the third resistor 11c is connected to the N pole of the high-voltage DC power supply 1, and the other end is connected to the other end of the second resistor 11b. A space between the first resistor 11a and the second resistor 11b is connected to a frame ground FG (for example, a chassis). The first voltage detecting circuit (first voltage detecting means) for detecting the voltage across the third resistor 11c as the leakage detection voltage V _N1 12, the second voltage detecting circuit for detecting the inverter input voltage V _PN (second voltage detection Means) 13 is provided. The leakage detection voltage V _N1 detected by the first voltage detection circuit 12 and the inverter input voltage V _PN detected by the second voltage detection circuit 13 are input to the microcomputer (processing means) 14. The microcomputer 14 detects the leakage at the five locations based on these input voltages.
In the system shown in FIG. 1, it is assumed that the P pole of the high-voltage DC power supply 1 and the frame ground are connected by an insulation resistor 16, and the N pole and the frame ground are connected by an insulation resistor 17.

Next, the principle of leakage detection in the leakage detection device 10 according to the present embodiment will be described with reference to FIG.
First, the principle of insulation deterioration at the P pole and N pole of the high-voltage DC power supply will be described. In the following description, the resistance value of the first resistor 11a is R _P1 , the resistance value of the second resistor 11b is R _N2 , the resistance value of the third resistor 11c is R _N1 , and the resistance value of the insulation resistor 16 is R The resistance value of _PX and the insulation resistance 17 is R _NX . In the present embodiment, the resistance values of the first resistor, the second resistor, and the third resistor are set so as to satisfy the relationship of R _P1 = R _N1 + R _N2 .

For example, in the circuit shown in FIG. 1, an equivalent circuit in the case of using an insulation resistance, a leakage detection resistance, and a high-voltage DC power supply as an element is a circuit as shown in FIG. 2. In the equivalent circuit of FIG. 2, in the normal state (R _PX = R _NX = ∞ [Ω]) in which the insulation resistances 16 and 17 are not deteriorated, the current flows as shown in FIG. The relationship between the detection voltage V _N1 , the inverter input voltage V _PN, and the resistance values R _P1 , R _N2 , and R _{N1 of} the first resistor 11a, the second resistor 11b, and the third resistor 11c is expressed by the following equation (1). .

Then, if only the insulation resistance 16 has insulation deterioration, as shown in FIG. 4, by the path through the R _PX is newly formed, changes the voltage dividing ratio by the voltage dividing resistors 11, the leakage detection voltage V _N1 increases. The relational expression at this time is shown in Expression (2). Further, the relational expression when only the insulation resistance 16 is short-circuited is shown in Expression (3).

As described above, when the insulation resistance 16 causes insulation deterioration, the leakage detection voltage V _N1 increases from the state of the above expression (1), and when it is finally short-circuited through the expression (2), it becomes the value of the expression (3). Show the characteristics.

Further, when only the insulation resistance 17 is deteriorated in insulation, as shown in FIG. 5, the path through R _NX is newly formed, so that the voltage dividing ratio by the voltage dividing resistor 11 is changed, and the leakage detection voltage V _N1 is changed. Decrease. The relational expression at this time is shown in Expression (4). Further, the relational expression when only the insulation resistance 17 is short-circuited is shown in Expression (5).

From the above, when the insulation resistance 17 causes insulation deterioration, the leakage detection voltage V _N1 decreases from the state of the above expression (1), and when it is finally short-circuited through the expression (4), it becomes the value of the expression (5). Show the characteristics.

Then, by conducting a test in advance and preparing a table showing the relationship between the leakage detection voltage V _N1 , the resistance value R _PX of the insulation resistor 16, and the resistance value R _NX of the insulation resistor 17, the insulation resistance is determined from the voltage V _N1 at both ends. The resistance values R _PX and R _NX of 16 and 17 can be detected, respectively, and the leakage of the P and N poles of the high-voltage DC power supply 1 can be detected without performing complicated processing.

FIG. 6 shows an example of a characteristic diagram showing the relationship between the leakage detection voltage V _N1 and the resistance values R _PX and R _NX of the insulation resistors 16 and 17 at a certain inverter input voltage V _PN . In FIG. 6, a region I indicates a region in which the resistance values R _NX and R _NX can be converted by detecting the leakage detection voltage V _N1 described above. When the resistance values R _PX and R _NX show normal values, they correspond to the positions of X1 and Y1 in the figure. When the insulation resistance 16 is deteriorated from this position and the resistance value R _PX gradually decreases. For example, when the voltage X2 is detected as the leakage detection voltage V _N1 , the resistance value R _{PX is} determined from the characteristics shown in FIG. = 10 [MΩ] is detected. Similarly, when the insulation resistance 17 is deteriorated and the resistance value R _NX gradually decreases. For example, when the voltage Y2 is detected as the leakage detection voltage V _N1 , the resistance value is determined from the characteristics shown in FIG. It can be seen that R _NX = 10 [MΩ].

However, the relationship between the leakage detection voltage V _N1 and the resistance values R _PX and R _NX varies depending on the inverter input voltage V _PN detected by the second voltage detection circuit 13 as in the above equations (1) to (4). . Thus, for example, by preparing the characteristic diagram shown in each category was partitioned into multiple levels inverter input voltage V _PN or each inverter input voltage V _PN 6, according to prevailing inverter input voltage V _PN The resistance values R _PX and R _NX are detected using the characteristic diagram. In this case, the insulation deterioration is determined depending on whether or not the detected resistance values R _PX and R _NX exceed a preset leakage threshold.

Further, one characteristic diagram as shown in FIG. 6 may be used, and the leakage threshold used for determining whether or not the insulation is deteriorated may be changed by the inverter input voltage _VPN . In this case, and an arithmetic expression for calculating the leakage threshold from inverter input voltage V _PN held microcomputer 14 substitutes the detected inverter input voltage V _PN by the second voltage detecting circuit 13 to the arithmetic expression Thus, the leakage threshold value is calculated, and the insulation deterioration is determined by comparing the leakage threshold value and the resistance values R _PX and R _NX detected using the characteristic diagram shown in FIG. In addition, this case is illustrated about the flow using FIG. 9 mentioned later.

Further, in place of the characteristic diagram shown in FIG. 6, a characteristic diagram showing the relationship between the ratio (V _N1 / V _NP ) of the leakage detection voltage V _N1 to the inverter input voltage V _PN and the resistance values R _PX and R _NX is used. It is good. In this case, the characteristic diagram in FIG. 6 is the characteristic in which the distribution of the magnitude relation is left as it is, and the title of V _N1 [V] on the right side of the graph is replaced with V _N1 / V _NP (no unit).
Further, in this case, as described above, the microcomputer 14, from the input leakage detection voltage V _N1 and the inverter input voltage V _PN, calculates the ratio of the leakage detection voltage V _N1 to the inverter input voltage V _PN, operation by detecting the resistance value R _PX and R _NX using the result and the characteristic diagram, it is also possible to determine the insulation deterioration. Alternatively, a threshold value may be set in advance in the ratio of the leakage detection voltage V _N1 to the inverter input voltage V _PN , and the insulation deterioration may be determined based on whether the calculation result exceeds the threshold value.

Next, the principle of leakage detection in a three-phase motor winding that supplies a three-phase alternating current will be described. Here, the leakage detection of the motor winding is performed after confirming that no insulation deterioration has occurred in both the P-pole and the N-pole of the above-described high-voltage DC power supply.
FIG. 7 is a diagram showing the internal configuration of inverter 2 and motor 3 in more detail in the circuit shown in FIG. The motor 3 and the frame ground are connected by an insulation resistor 18.
When detecting insulation deterioration of the motor winding, one of the lower arms of the bridge circuit constituting the inverter 2 is turned on. An equivalent circuit in this state is shown in FIG. In FIG. 8, the resistance value of the insulation resistor 18 is indicated by R _MX .

As shown in FIG. 8, the equivalent circuit for detecting leakage in the three-phase AC power transmission line is the same as the circuit in which R _PX = ∞ [Ω] and R _NX = R _MX in the equivalent circuit shown in FIG. . Therefore, when the insulation resistance 18 is deteriorated, the equivalent circuit shown in FIG. 2 can be considered equivalent to the case where the insulation resistance 18 is deteriorated, that is, when the resistance value R _NX is decreased. The leakage detection pressure V _N1 decreases.
Specifically, when the resistance value R _MX of the insulation resistor 18 is decreased, the leakage detection voltage V _N1 is decreased from the state of the above expression (1), and when it is finally short-circuited through the expression (4), the expression (5) The characteristic which becomes the value of is shown. Here, in the formulas (1), (4), and (5), R _NX is replaced with R _MX .

In the characteristic diagram shown in FIG. 6, the insulation deterioration of the insulation resistance R _MX can be similarly detected by replacing the insulation resistance R _NX with R _MX . In FIG. 6, a region II indicates a region where the resistance value R _MX can be converted by detecting the leakage detection voltage V _N1 .
As described above, when detecting the insulation deterioration of the transmission path of the three-phase AC power, the leakage detection voltage V _N1 is detected in a state where any one of the lower arms of the bridge circuit of the inverter 2 is turned on. By determining whether or not the both-end voltage V _N1 has decreased, it is possible to easily detect a leakage in the transmission path of the three-phase AC power without performing complicated processing. Further, by preparing the characteristic diagram in FIG. 6 for each inverter input voltage V _PN or for each section in which the inverter input voltage V _PN is _divided into a plurality of levels, the insulation resistance R is obtained from the both-end voltage V _N1 and the inverter input voltage V _PN. The resistance value of _MX can be known.

In the case of detecting the insulation deterioration of the transmission path of the three-phase AC power, the characteristic diagram as shown in FIG. The leakage threshold used for determining whether or not the insulation is deteriorated may be changed by the inverter input voltage _VPN . Further, in place of the characteristic diagram as shown in FIG. 6, a characteristic diagram showing the relationship between the ratio (V _N1 / V _NP ) of the leakage detection voltage V _N1 to the inverter input voltage V _PN and the resistance value R _MX is used. It is good as well. Alternatively, a threshold value may be set in advance in the ratio of the leakage detection voltage V _N1 to the inverter input voltage V _PN , and the insulation deterioration may be determined based on whether the calculation result exceeds the threshold value.

Next, the procedure of leakage detection by the leakage detection device 10 according to the present embodiment will be described with reference to FIG. FIG. 9 is a flowchart showing a processing procedure of leakage detection according to the present embodiment.
First, the high-voltage DC power supply 1 is operated, and a high-voltage DC voltage is applied to the circuit shown in FIG. 1 (step SA1 in FIG. 9). At this time, all the switching elements of the bridge circuit constituting the inverter 2 are turned off. Subsequently, the first voltage detection circuit 12 and the second voltage detection circuit 13 detect the leakage detection voltage V _N1 and the inverter input voltage V _PN (step SA2 in FIG. 9). The detected leakage detection voltage V _N1 and the inverter input voltage V _PN are input to the microcomputer 14. Subsequently, the microcomputer 14 detects the values of the insulation resistances R _PX and R _NX corresponding to the leakage detection voltage V _N1 using the leakage detection voltage V _N1 , the inverter input voltage V _PN and the characteristic diagram shown in FIG. (Step SA3 in FIG. 9).

Next, leakage detection is performed based on the detected resistance values R _PX and R _NX of the insulation resistances 16 and 17 (step SA4 in FIG. 9). The leakage detection is performed by, for example, determining whether or not the detected resistance values R _PX and R _NX are equal to or less than a leakage threshold determined by the inverter input voltage _VPN . As a result, if no leakage has occurred (“YES” in step SA4 in FIG. 9), then the leakage detection of the transmission path of the three-phase AC power starts. Specifically, any one of the lower arms of the inverter 2 is turned on (step SA5 in FIG. 9), and in this state, the leakage detection voltage V _N1 is detected by the first voltage detection circuit 12 (step SA6 in FIG. 9). ). Subsequently, by using the inverter input voltage V _PN detected in step SA2, the leakage detection voltage V _N1 detected in step SA5, and the characteristic diagram shown in FIG. 6, the insulation resistance 18 corresponding to the leakage detection voltage V _N1 The resistance value R _MX is detected (step SA7 in FIG. 9).

Next, leakage detection is performed based on the detected resistance value R _MX (step SA8 in FIG. 9). The leakage detection is performed, for example, by determining whether or not the detected insulation resistance R _MX is equal to or less than a leakage threshold determined by the inverter input voltage _VPN . As a result, if no leakage has occurred ("YES" in step SA8 in FIG. 9), the leakage detection ends. Thereby, for example, the drive of the inverter 2 is started and the power supply to the motor 3 is started.

  On the other hand, when a leakage is detected in step SA4 or SA8, the system is stopped (step SA9 in FIG. 9). Specifically, when leakage is detected, activation of the inverter 2 and the like is avoided to prevent activation of the electric compressor and the like, and the fact that leakage has been detected is also notified to the upper component. At this time, there are two types of information to be notified, and there are insulation degradation of the component itself (electric compressor itself) and insulation degradation of the upper part of the component.

The insulation deterioration of the component itself is notified when the insulation deterioration is detected at any of the above five locations, and the insulation deterioration above the component is the case where the insulation deterioration is detected at the P pole or N pole of the high-voltage DC power supply 1 To be notified.
When the insulation deterioration of the component itself is notified, the operation command for the electric compressor is stopped, the high voltage power to the electric compressor is cut off, the high voltage system of the entire vehicle is cut off, and the vehicle crew is notified.
In addition, when the insulation deterioration of the upper part of the component is notified, the start and stop of the upper part of the component, the interruption of the high voltage system of the entire vehicle, the notification to the vehicle crew, etc. are performed.
By taking such measures, the progress of insulation deterioration can be prevented, and damage due to electric leakage can be minimized.

As described above, according to the leakage detection device and the method thereof according to the present embodiment, the first resistor 11a, the second resistor 11b, and the third resistor 11c are disposed between the P pole and the N pole of the high-voltage DC power supply 1. They were connected in series, and detects the voltage across the third resistor 11c as the leakage detection voltage V _N1 detects the inverter input voltage V _PN, the high-voltage DC power source 1 on the basis of the leakage detection voltage V _N1 and the inverter input voltage V _PN P pole and N pole insulation degradation and insulation degradation in the three-phase AC power transmission path (U, V, W three phases) are detected. As a result, there is an effect that it is possible to efficiently detect insulation deterioration in a total of five places with a small number of parts.

[Second Embodiment]
Next, a leakage detection apparatus and method according to a second embodiment of the present invention will be described.
In the leakage detection device 10 according to the first embodiment described above, the insulation deterioration of the insulation resistors 16 and 17 is detected from the leakage detection voltage V _N1 . However, in the above method, the resistance values R _PX of the insulation resistors 16 and 17 and When insulation degradation has occurred in both R _NX , there is a disadvantage that insulation degradation cannot be detected. That is, in the equivalent circuit as shown in FIG. 2, when the equilibrium condition shown in the following equation (6) is satisfied, the currents flowing through the equivalent circuit are balanced and the currents as shown in FIG. 4 and FIG. The flow will not be noticeable.

In this case, the leakage detection voltage V _N1 shows the same value as in the normal state, and it becomes impossible to detect the insulation deterioration of both the insulation resistances 16 and 17 (corresponding to the region III in FIG. 6). To do). The leakage detection device and the method thereof according to the present embodiment aim to solve such problems.

FIG. 10 shows the configuration of the leakage detection apparatus according to this embodiment. As shown in FIG. 10, the leakage detection device according to the present embodiment is configured such that the first resistor 11 a of the leakage detection device according to the first embodiment shown in FIG. 1 is configured as a variable resistor, and the resistance value of the first resistor 11 a. detecting twice the leakage detection voltage V _N1 by changing judges insulation deterioration of the insulation resistance 16 and 17 on the basis of this result and the inverter input voltage V _PN.

For example, the first resistor 11a is opened at the time of detecting the second leakage detection voltage V _N1 .
When the first resistor 11a is opened, the leakage detection voltage V _N1 is expressed by the following equation (7).

FIG. 11 is a characteristic diagram when the first resistor 11a is opened. For example, in the characteristic diagram shown in FIG. 6, when the relationship between the insulation resistances _RPX and _RNX is located in the region III, the points A, B, and C cannot be distinguished. In the characteristic diagram shown, the leakage detection voltage V _N1 (positioned in region IV) at point A is different from the point B and the leakage detection voltage V _N1 (positioned in region III) at point C. It can be seen that it can be distinguished from the C point.
Thus, by changing the resistance value of the first resistor 11a and changing the voltage dividing ratio of the voltage dividing resistor 11, it is possible to reliably detect the insulation deterioration of the insulation resistors 16 and 17.

In the characteristic diagram shown in FIG. 11, point B and point C indicate the same leakage detection voltage V _N1 , so it is difficult to distinguish them. However, both points B and C are areas where the insulation deterioration has progressed, and there is no problem in terms of leakage detection function as long as it can be distinguished from point A as described above.

Next, a specific method for making the first resistor 11a variable will be described with reference to FIG. For example, as shown in FIGS. 12A to 12F, the resistor 20 is connected in parallel or in series with the first resistor 11a, and the resistor 20 is connected to the first resistor 11a by turning on and off the switching element 21. By connecting, the resistance value R _P1 is changed.
Further, as shown in FIGS. 12 (g) to (i), the switching element 21 is connected either before or after the first resistor 11a, and the first resistor 11a is connected to the circuit by turning on / off the switching element 21. By opening, the resistance value R _{P1 becomes} infinite.
The means shown here is an example, and the method of making the first resistor 11a variable is not limited to this example.

Next, the procedure of leakage detection by the leakage detection device according to the present embodiment will be described with reference to FIG. FIG. 13 is a flowchart showing a procedure of leakage detection by the leakage detection apparatus according to the present embodiment. First, the high-voltage DC power supply 1 is operated to apply a high-voltage DC voltage to the circuit (step SA1 in FIG. 13). At this time, the resistance value R _P1 of the first resistor 11a is set to be the same as that of the first embodiment, that is, the condition of R _P1 = R _N1 + R _N2 is satisfied. Subsequently, the first voltage detection circuit 12 and the second voltage detection circuit 13 detect the leakage detection voltage V _N1 and the inverter input voltage V _PN (step SA2 in FIG. 13). These detected voltage values are input to the microcomputer 14.

Next, the resistance value R _P1 of the first resistor 11a is changed according to a command from the microcomputer 14 (step SB1 in FIG. 13). Here, the first resistor 11a is opened to be infinite. In this state, the first voltage detection circuit 12 detects the leakage detection voltage V _N1 (step SB2 in FIG. 13). The detected leakage detection voltage V _N1 is input to the microcomputer 14.
The microcomputer 14 uses a characteristic diagram showing the leakage detection voltage V _N1 and 11 detected by the characteristic diagram and step SB2 shown in the leakage detection voltage V _N1 and 6 detected in step SA2, the insulation resistance The values of R _PX and R _NX are detected (step SB3 in FIG. 13). Then, the electric leakage detection based on the resistance value _{R PX} and _{R NX} of the detected insulation resistance 16, 17 (step SA4 in FIG. 13). Steps SA4 to SA9 are the same as those in the first embodiment described above, and thus the description thereof is omitted.

As described above, according to the leakage detection device and the method thereof according to the present embodiment, the leakage resistance detection voltage V _N1 is detected twice by changing the resistance value of the first resistance 11a and changing the resistance value of the first resistance 11a. In addition, since the insulation deterioration of the P pole and the N pole of the high voltage DC power supply 1 is detected based on the two leakage detection voltages V _N1 and the inverter input voltage V _PN , both the P pole and the N pole of the high voltage DC power supply 1 are detected. Even when the insulation deterioration that maintains the equilibrium state of the equivalent circuit occurs, it becomes possible to reliably detect the insulation deterioration.

Although the case where the first resistor 11a is variable has been described in the present embodiment, the second resistor 11b and the third resistor 11c may be variable instead of or in addition to the first resistor 11a. .
In this embodiment, the leakage detection voltage is detected twice by changing the value of the first resistance. However, the leakage detection is performed by changing the resistance values of the first resistance, the second resistance, and the third resistance a plurality of times. The voltage may be detected three or more times, and the resistance value of the insulation resistance may be detected based on the three or more leakage detection voltages and the inverter input voltage _VPN .

In the first or second embodiment, the resistance values of the insulation resistances R _PX , R _NX , and R _MX are obtained using the characteristic diagrams shown in FIGS. 6 and 11. For example, as shown in FIGS. 14A and 14B, the resistance value of the insulation resistance is obtained using a table in which the leakage detection voltage V _N1 is associated with the resistance value of each insulation resistance. Also good. Further, instead of the table, an arithmetic expression showing the relationship between the leakage detection voltage V _N1 and the resistance value of each insulation resistance may be used. It is assumed that such data is stored in a predetermined storage area of the microcomputer 14.

Further, in the first or second embodiment obtains the resistance values of the insulation resistance from the leakage detection voltage V _N1 and the inverter input voltage V _PN, although the leakage detection has been performed based on this, each determined that leakage The range of the leakage detection voltage V _N1 corresponding to the resistance value of the insulation resistance may be recorded, and the leakage may be determined when the leakage detection voltage V _N1 is within the voltage range. For example, when the leakage detection voltage V _N1 is equal to or higher than the first threshold determined by the inverter input voltage V _PN , the insulation deterioration of the P pole of the high-voltage DC power supply 1 is detected, and the leakage detection voltage V _N1 is the inverter input voltage. When it becomes less than the second threshold value determined by the _VPN , it is possible to detect insulation deterioration in the transmission line of the N pole or the three-phase AC power of the high-voltage DC power supply 1.
In this case, arithmetic expressions for calculating the first threshold value and the second threshold value from the inverter input voltage _VPN are preset in the microcomputer 14, and the first threshold value and the second threshold value are calculated using the arithmetic expressions. Is calculated.

  By doing so, it is possible to save the trouble of converting the voltage into the resistance value and to detect the leakage even more easily.

DESCRIPTION OF SYMBOLS 1 High voltage direct current power source 2 Inverter 3 Motor 10 Leakage detection apparatus 11 Voltage dividing resistor 11a 1st resistor 11b 2nd resistor 11c 3rd resistor 12 1st voltage detection circuit 13 2nd voltage detection circuit 14 Microcomputer 16, 17, 18 Insulation resistance 20 Resistor 21 Switching element

Claims (7)

In a system including a DC power supply, an inverter that converts DC power supplied from the DC power supply into three-phase AC power, and a motor that is supplied with the three-phase AC power output from the inverter, An earth leakage detection device that detects insulation deterioration of P and N poles and insulation deterioration in the transmission path of the three-phase AC power,
A first resistor having one end connected to the P pole of the DC power supply;
A second resistor having one end connected to the other end of the first resistor and connected to a frame ground;
A third resistor having one end connected to the other end of the second resistor and the other end connected to the N pole of the DC power source;
First voltage detection means for detecting a voltage across the third resistor as a leakage detection voltage;
Second voltage detecting means for detecting the inverter input voltage;
Processing means,
The processing means detects an insulation deterioration of the P pole and the N pole of the DC power source using the leakage detection voltage and the inverter input voltage when the upper arm and the lower arm of the inverter are turned off, and the inverter A leakage detection device that detects insulation deterioration in the transmission path of the three-phase AC power based on the leakage detection voltage and the inverter input voltage when any one of the lower arms is turned on.   The processing means includes an insulation resistance connecting the P pole of the DC power supply and the frame ground, a relationship between the leakage detection voltage and the inverter input voltage, and an insulation resistance connecting the N pole of the DC power supply and the frame ground. Information indicating the relationship between the leakage detection voltage and the inverter input voltage, the insulation resistance connecting the transmission path of the three-phase AC power and the frame ground, and the relationship between the leakage detection voltage and the inverter input voltage, respectively. The insulation resistance value is obtained based on the information, the leakage detection voltage detected by the first voltage detection means, and the inverter input voltage, and the leakage current is obtained based on the obtained insulation resistance value. The leakage detection device according to claim 1, wherein   The processing means detects an insulation deterioration of the P pole of the DC power supply when the leakage detection voltage is equal to or higher than a first threshold determined by the inverter input voltage, and the leakage detection voltage is determined by the inverter input voltage. The leakage detecting device according to claim 1, wherein when it becomes less than a second threshold value, insulation deterioration in the N pole of the DC power supply or the transmission path of the three-phase AC power is detected. At least one of the first resistor, the second resistor, and the third resistor has a variable resistance value.
The processing means changes at least one of the first resistance, the second resistance, and the third resistance,
The first voltage detection means detects the leakage detection voltage at least twice in a combination of the first resistor, the second resistor, and the third resistor having different voltage division ratios,
The processing means includes at least two leakage detection voltages detected by the first voltage detection means and the inverter input voltage detected by the second voltage detection means, based on the P pole and the N pole of the DC power supply. The leakage detection device according to any one of claims 1 to 3, which detects an insulation deterioration of the battery. In a system including a DC power supply, an inverter that converts DC power supplied from the DC power supply into three-phase AC power, and a motor that is supplied with the three-phase AC power output from the inverter, A leakage detection method for detecting insulation deterioration of P and N poles and insulation deterioration in the transmission path of the three-phase AC power,
One end of the first resistor connected to the P pole of the DC power source, one end connected to the other end of the first resistor and a second resistor connected to the frame ground, and one end connected to the second resistor A third resistor connected to the other end and having the other end connected to the N pole of the DC power supply is connected between the P pole and the N pole of the DC power supply;
The inverter input voltage is detected by operating the DC power supply to apply a voltage, and the voltage across the third resistor in this state is detected as a leakage detection voltage, and the detected leakage detection voltage and the inverter input voltage are detected. Is detected based on the leakage detection voltage and the inverter input voltage when any one of the lower arms of the inverter is turned on. A leakage detection method for detecting insulation deterioration in a phase AC power transmission line. The DC power supply is a high voltage power supply mounted on a vehicle,
The motor is a motor used for an electric compressor included in an in-vehicle air conditioner,
When the leakage detection device according to any one of claims 1 to 4 detects insulation deterioration of the P-pole or N-pole of the DC power supply, starting and stopping of the upper components and shutting off the high-voltage system of the entire vehicle And a leakage countermeasure method that implements at least one of notifications to the vehicle crew. The DC power supply is a high voltage power supply mounted on a vehicle,
The motor is a motor used for an electric compressor included in an in-vehicle air conditioner,
When the leakage detection device according to any one of claims 1 to 4 detects insulation deterioration of the P-pole or N-pole of the DC power supply or insulation deterioration in any of the transmission paths of the three-phase AC power. A leakage countermeasure method that implements at least one of stop of an operation command for the electric compressor, interruption of high voltage power to the electric compressor, interruption of a high voltage system of the entire vehicle, and notification of leakage to a vehicle crew.

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