JP2005020848A - Leakage detection system of car - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To simplify circuit configuration for a reduced cost by dispensing with the dedicated power supply of a leakage detection device. <P>SOLUTION: In the electric system of a car, a vehicle driving motor is driven with the electric power of an onboard DC power supply through an inverter, and the energized part containing a feeder line to the motor is electrically insulated from a car body. A leakage detection device 100A comprises 101a, 101b, 101c, CT102a, 102b, and 102c, and leakage sensors 110a, 110b, and 110c, with an AC voltage generated on the AC output side of an inverter 4 as a power source. The leakage detection device 100A senses leakage from the energized parts such as feeder lines 63P, 63N, 64a, 64b, and 64c to a car body 9. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a vehicle leakage detection system for detecting leakage to a vehicle body equipped with a DC power supply having a rated voltage of, for example, 50 V or more.
[0002]
[Prior art]
FIG. 13 shows a basic configuration of an electric system when electric driving is performed in an electric vehicle or a hybrid vehicle.
In the figure, 1 is a main battery as a first in-vehicle DC power source having a rated voltage of, for example, 100V or more, 2P and 2N are fuses, 3 is a DC contactor, 4 is a voltage-type inverter for driving the vehicle drive motor 10, 5 Is an AC contactor. Further, 61P, 61N, 62P, 62N, 63P, 63N, 64a, 64b, and 64c are power supply lines (main circuit harnesses), the suffix P indicates the positive electrode side, and N indicates the negative electrode power supply line. Note that the fuses 2P and 2N and the AC contactor 5 may be omitted.
Further, 41 is a current smoothing input capacitor of the inverter 4, and 42 is a semiconductor switch section. Since the driving method of the electric motor 10 by the inverter 4 is known, the description of the control content is omitted here.
[0003]
A battery mounted on an engine vehicle that uses an internal combustion engine as a power source is usually a low voltage of 12 V or 24 V, and the negative electrode side is connected to the vehicle body.
On the other hand, in the electric system shown in FIG. 13, since the main battery voltage is 100 V or more, the energizing part including the feeder is electrically insulated from the vehicle body for safety. For this reason, as one of the important solutions in an electric system such as an electric vehicle, it is possible to detect electric leakage from the drive circuit to the vehicle body and prevent human electric shock.
[0004]
FIG. 14 shows an example of a leakage detection system employed in the electrical system of FIG. 13 as the first prior art.
In FIG. 14, 7 is a leakage detection device, 71 is a high frequency power supply, 72 is a capacitor, 73 is a CT (current transformer) as a current detector, 74 is a leakage current detection circuit connected to the CT 73, and 8 is at the time of leakage detection. A vehicle control device for performing a predetermined protection operation, 9 is a vehicle body, and the other components are denoted by the same reference numerals as in FIG.
One end of the capacitor 72 is connected to the positive-side power supply line 63P.
[0005]
14 will be described with reference to FIGS. 15 and 16. FIG.
First, referring to FIG. 15, a leakage detection operation in the case where the insulation of the positive-side power supply line 63 </ b> P or the current-carrying part (not shown) is deteriorated will be described. In FIG. 15, reference numeral 200 </ b> P is an insulation resistance equivalently showing a leakage portion between the positive-side power supply line 63 </ b> P or the energization portion and the vehicle body 9.
Since the leakage current indicated by the arrow in FIG. 15 flows from the high-frequency power source 71 through the capacitor 72, the feeder line 63P, and the equivalent insulation resistance 200P, this current can be detected by the CT 73.
[0006]
Next, with reference to FIG. 16, the leakage detection operation in the case where the insulation of the negative-side power supply line 63N or the current-carrying part is deteriorated will be described. In FIG. 16, 200 N is an insulation resistance that equivalently indicates a leakage portion between the negative-side power supply line 63 N or the energization portion and the vehicle body 9. Since the leakage current indicated by the arrow in FIG. 16 flows from the high-frequency power source 71 through the capacitor 72, the feeder line 63P, the capacitor 41, the feeder line 63N, and the equivalent insulation resistance 200N, this current can be detected by the CT 73.
[0007]
15 and 16, the current I flowing on the primary side of CT73_l(Effective value) is expressed by Equation 1.
[0008]
[Equation 1]
I_l= E / {(1 / 2πfC)²+ R_l ²  }^1/2
here
E: Voltage (effective value) of high frequency power supply 71 [V]
f: Frequency of the high frequency power supply 71 [Hz]
C: Capacity of capacitor 72 [F]
R_l: Equivalent insulation resistance 200P or 200N resistance [Ω]
[0009]
Note that f and C in Equation 1 are equivalent insulation resistance values R at the leakage level to be detected._l0In contrast, Formula 2 is determined to hold.
[0010]
[Equation 2]
(1 / 2πfC) <R_l0
[0011]
Next, FIG. 17 shows a basic configuration of another electric system when electric driving is performed in an electric vehicle or a hybrid vehicle.
In the figure, the same components as those in FIG. 13 are denoted by the same reference numerals, and the description thereof is omitted. Hereinafter, different portions will be mainly described.
[0012]
In FIG. 17, reference numeral 90 denotes an auxiliary battery as a second in-vehicle DC power supply, which generally has a rated voltage of 12 V or 24 V, and its negative electrode is connected to the vehicle body 9. 91 is a DC-DC converter for converting the DC power of the main battery 1 to charge the auxiliary battery 90, 92 is a DC contactor, 93P and 93N are auxiliary fuses, and 94 is a lighting device or sound source using the auxiliary battery 90 as a power source. In-vehicle devices such as devices, 900P and 900N are power supply lines of the DC-DC converter 91.
Note that the fuses 93P and 93N may be omitted.
[0013]
FIG. 18 shows an example of the circuit configuration of the DC-DC converter 91 in FIG. 17, and shows an example using a known two-stone forward type DC-DC converter.
In FIG. 18, 910 is an input capacitor, 911P and 911N are semiconductor switching elements, 912P and 912N are diodes, 913 is a high frequency isolation transformer, 913P is its high voltage winding, 913S is a low voltage winding, 914 is a rectifier, 914a and 914b Is a diode, 915 is a current smoothing reactor, and 916 is a current smoothing capacitor.
[0014]
In the DC-DC converter 91, the semiconductor switching elements 911P and 911N are switched at a high frequency of several tens of kHz or more to generate a high-frequency AC voltage in the high-voltage winding 913P of the transformer 913. Then, a high-frequency AC voltage that is insulated and lowered is generated in the low-voltage winding 913 </ b> S, and this voltage is converted into a DC voltage by the rectifier 914, and then smoothed and supplied to the auxiliary battery 90.
Further, the output voltage of the DC-DC converter 91 is changed by controlling the conduction ratio of the semiconductor switching elements 911P and 911N, and the charging current of the auxiliary battery 90 is controlled.
Since the control method and operation of this type of two-stone forward type DC-DC converter are known, for example, from Japanese Patent Laid-Open No. 5-336742 "Two-stone forward type switching power supply", detailed description thereof is omitted here. .
[0015]
Also in the electrical system shown in FIGS. 17 and 18, the above-described leakage detection system as shown in FIG. 14 is applied, and the operation is the same as in FIGS. 15 and 16.
[0016]
Note that a power supply device for an electric vehicle having a leakage detection function as in the prior art is described in Patent Document 1 below.
The power supply device includes a battery that supplies power to a traveling motor and the like, an inverter that is supplied with power from the battery and supplies a commercial AC voltage to a commercial power supply load, and a cutoff switch that is interposed between the commercial power supply load and the battery. And a leakage detection circuit that cuts off the cutoff switch when the ground fault current leaking from the battery is equal to or greater than a predetermined value. The leakage detection circuit includes a power supply circuit system for a commercial power load, a traveling motor, etc. This is to detect a leakage of the power feeding circuit system.
[0017]
[Patent Document 1]
JP-A-10-290529 (Claim 1, Claim 2, FIG. 1, FIG. 2, etc.)
[0018]
[Problems to be solved by the invention]
In electric vehicles and hybrid vehicles equipped with a DC power supply with a rated voltage of 50 V or higher, all current-carrying parts including the power supply line from this DC power supply are electrically insulated from the vehicle body, and the vehicle It is necessary to ensure the safety of the human body by reliably detecting the leakage of electricity with the leakage detection device.
In this case, as a leakage detection system,
(1) The device configuration is simple.
(2) The equipment is inexpensive
(3) High operational reliability
Etc. are required as a solution issue.
[0019]
However, the leakage detection device 7 shown in FIG. 14 requires a high-frequency power source 71 as a dedicated power source. In addition, the leakage detection system described in Patent Document 1 includes an oscillation circuit unit having a rectangular wave oscillator, an impedance converter, and the like, and a detection circuit having a comparator, etc. Generally complex.
[0020]
Accordingly, the present invention is intended to solve the various problems required for the above-described leakage detection system, and to provide a leakage detection system that is simple in configuration, inexpensive, and highly reliable.
[0021]
[Means for Solving the Problems]
In order to solve the above problems, the inventions described in claims 1 to 4 have been made paying attention to the fact that the voltage output from the vehicle drive inverter to the vehicle drive motor is an AC voltage.
The inventions described in claims 5 to 9 focus on the fact that the operating voltage of the insulation transformer of the DC-DC converter for charging the auxiliary battery which is the second in-vehicle DC power supply is a high-frequency AC voltage. It was made.
The inventions described in claims 10 to 14 further embody the invention described in the above claims.
[0022]
That is, according to the first aspect of the present invention, the vehicle drive motor is driven via the inverter by the electric power of the on-vehicle DC power source, and the energization portion including the power supply line to the motor is electrically insulated from the vehicle body. In the automotive electrical system
An electric leakage detection device using an AC voltage generated on the AC output side of the inverter as a power source is detected, and the electric leakage detection device detects electric leakage from the energization section to the vehicle body.
[0023]
According to a second aspect of the present invention, there is provided a vehicle electric leakage detection system according to the first aspect,
The leakage detection device comprises a series circuit of a capacitor and a current detector connected between the AC output side of the inverter and the vehicle body,
The leakage of the energization unit is detected from the value of the current flowing through the current detector.
[0024]
According to a third aspect of the present invention, there is provided a vehicle electric leakage detection system according to the first or second aspect,
The leakage detection device includes a series circuit including a capacitor connected in a star shape to the AC output side of the inverter and a current detector connected between a neutral point of the capacitor and the vehicle body, and the current detector The leakage of the current-carrying part is detected from the value of the current flowing through the current.
[0025]
The invention described in claim 4 is the vehicle electric leakage detection system according to any one of claims 1 to 3,
Before the automobile is driven, the inverter is activated to detect a leakage of the energization unit.
[0026]
The invention described in claim 5 supplies the power of the first in-vehicle DC power source to the second in-vehicle DC power source via the insulation type DC-DC converter, and from the first in-vehicle DC power source through the inverter. In an automobile electrical system that drives a vehicle drive motor and a current-carrying portion including a power supply line to the motor is electrically insulated from the vehicle body, an AC voltage generated inside the DC-DC converter is used as a power source. The leakage detecting device detects the leakage from the current-carrying portion to the vehicle body.
[0027]
According to a sixth aspect of the present invention, there is provided a vehicle electric leakage detection system according to the fifth aspect,
The leakage detection device uses an AC voltage generated in a winding on the first in-vehicle DC power supply side of an insulation transformer provided in the DC-DC converter as a power source.
[0028]
According to a seventh aspect of the present invention, there is provided a vehicle electric leakage detection system according to the sixth aspect of the present invention.
The leakage detection device includes:
A series circuit of a capacitor and a current detector connected between the winding on the first in-vehicle DC power supply side of the insulation transformer and the vehicle body;
The leakage of the energization unit is detected from the value of the current flowing through the current detector.
[0029]
The invention described in claim 8 is the vehicle electric leakage detection system according to claim 6 or 7,
The leakage detection device includes:
A plurality of capacitors connected in series between both ends of the winding on the first in-vehicle DC power supply side of the insulation transformer, and a current detector connected between an interconnection point of these capacitors and the vehicle body; With
The leakage of the energization unit is detected from the value of the current flowing through the current detector.
[0030]
The invention described in claim 9 is the vehicle electric leakage detection system according to any one of claims 5 to 8,
Prior to driving the automobile, the DC-DC converter is activated to detect a leakage of the energization unit.
[0031]
In each of the above inventions, as described in claim 10, the current flowing through the current detector is detected through a low-pass filter, and when this detected current value exceeds a specified value, the occurrence of leakage is detected. desirable.
In addition, as described in claim 11 or 13, the in-vehicle DC power source or the first in-vehicle DC power source is assumed to have a rated voltage of 50 V or more.
Furthermore, as described in claim 12 or 14, a secondary battery, an electrolytic capacitor, an electric double layer capacitor, a fuel cell, a rectifier, or the like can be applied as the in-vehicle DC power source or the first in-vehicle DC power source.
[0032]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a circuit configuration diagram showing a first embodiment of the present invention. The same components as those in FIGS. 13 and 17 are denoted by the same reference numerals, and the description thereof will be omitted. Hereinafter, different portions will be mainly described.
[0033]
In FIG. 1, reference numeral 100A denotes a leakage detection device, one end of which is connected to each of the power supply lines 64a, 64b and 64c, and the other end is connected to the vehicle body 9 in a lump (that is, a star-connected capacitor) 101a, 101b, 101c, CTs 102a, 102b, 102c each having a primary side connected between the other end (neutral point) of these capacitors 101a, 101b, 101c and the vehicle body 9, and their secondary side and vehicle control It is comprised from the earth-leakage detection part 110a, 110b, 110c connected between the apparatuses 8, respectively.
[0034]
The leakage detection unit 110a is configured by sequentially connecting a current detection circuit 103a, a low-pass filter 104a, and a leakage detection circuit 105a. Similarly, the leakage detection unit 110b includes a current detection circuit 103b, a low-pass filter 104b, and a leakage detection circuit 105b. The leakage detection unit 110c includes a current detection circuit 103c, a low-pass filter 104c, and a leakage detection circuit 105c.
Note that the leakage detection operation of this embodiment is substantially the same as the operation of the second embodiment, as will be described later.
[0035]
FIG. 2 is a circuit configuration diagram showing a second embodiment of the present invention, and the same reference numerals are assigned to the same components as those in FIG.
1 is different from FIG. 1 in that a common CT 102 is connected between the neutral point of the star-connected capacitors 101a, 101b, and 101c and the vehicle body 9, and the secondary side thereof. Is connected to a common leakage detection unit 110 including a current detection circuit 103, a low-pass filter 104, and a leakage detection circuit 105.
[0036]
Next, the operation of the embodiment of FIG. 2 will be described.
FIG. 3 shows the main part of FIG. 2, and is an operation explanatory diagram when there is no leakage from the feeder lines 64a and 64b. The voltage source inverter 4 in FIG. 2 is shown as a three-phase inverter, but in FIG. 3, two arms of the A phase and the B phase are shown in the three phases of the semiconductor switch unit 42, and each of these arms is derived from the IGBT. It is comprised by the semiconductor switching elements 421-424 which become. Note that free-wheeling diodes are connected in antiparallel to all three-phase semiconductor switching elements of the semiconductor switch unit 42, but these are not shown. In FIG. 3, a is an A-phase output terminal, and b is a B-phase output terminal.
[0037]
Since there is no leakage from the power supply lines 64a and 64b, the insulation resistance of the vehicle body 9 is infinite. Therefore, when the semiconductor switching element 422 is turned on, the current I passes through the capacitors 101a and 101b as shown by the arrow._cFlows, but the current I through CT102_lIs zero.
[0038]
FIG. 4 is an operation waveform diagram of FIG.
In FIG._ab3 is a voltage waveform between the phase output terminals a and b in FIG. 3, and the DC input voltage V of the voltage source inverter 4_dIs a rectangular wave voltage with an amplitude of.
I_cIs a current waveform flowing through the capacitors 101a and 101b, and the voltage V_abA pulsed current flows according to dv / dt at the time of rising and voltage falling. I_lIs a leakage current waveform flowing through the CT 102, and is zero because there is no leakage as described above.
[0039]
FIG. 5 is a diagram illustrating a main part of FIG. 2 when the B-phase power supply line 64b on the output side of the inverter 4 has a leakage current, and 201b is an equivalent insulation resistance indicating a leakage part of the power supply line 64b.
Between the output terminals a and b of the semiconductor switch section 42, the same voltage V as in FIG._abThis voltage V_abThus, when the semiconductor switching element 424 is turned on, the current indicated by the arrow flows through the capacitor 101a and the equivalent insulation resistance 201b to the CT 102.
[0040]
FIG. 6 is an operation waveform diagram of FIG. Current I_cVoltage V_abThe current corresponding to dv / dt at the time of rising and falling of is the same as in FIG._abLeakage current I corresponding to the waveform of_rFlows through the equivalent insulation resistance 201b. This leakage current I_rIs represented by Equation 3.
[0041]
[Equation 3]
I_r= V_d/ R_d[A]
Where V_d: Inverter 4 DC input voltage [V]
R_d: Resistance value [Ω] of the equivalent insulation resistance 201b of the leakage portion
It is.
[0042]
That is, CT102 includes I in FIG._cAs shown by the voltage V_abCurrent corresponding to dv / dt at the time of rising and falling (I in FIG._cAnd I shown in Equation 3_rA combined current flows. Note that the current I in FIG._lIs the current I flowing through CT102_cThe average value of_rmAnd
[0043]
Current I flowing through CT102_c2 is detected by the current detection circuit 103 in FIG. 2 and averaged by removing high frequency components by the low-pass filter 104 and input to the leakage detection circuit 105.
In the leakage detection circuit 105, the input current value (I in FIG._rm) Exceeds the specified value, it is determined that leakage has occurred, and a signal is sent to the vehicle control device 8 to perform necessary protective measures such as opening the DC contactor 3 and generating an alarm.
[0044]
The above description is the operation at the time of leakage of the B-phase power supply line 64b, but the operation is substantially the same at the time of leakage of the A-phase power supply line 64a and the remaining one-phase (C-phase) power supply line 64c.
In the first embodiment shown in FIG. 1, the operation of the leakage detection units 110a, 110b, 110c when the power supply lines 64a, 64b, 64c on the output side of the inverter 4 are leaked is also substantially the same as described above. Therefore, the description is omitted.
[0045]
Here, the first embodiment of FIG. 1 has an advantage that it is possible to individually detect which power supply line includes a power supply line among the power supply lines 64a, 64b, and 64c of the inverter 4.
[0046]
Next, FIG. 7 is an explanatory diagram of a main part when a leakage occurs on the input side of the inverter 4 in the second embodiment, assuming a leakage in the positive-side power supply line 63P. In FIG. 7, 201P is an equivalent insulation resistance of the leakage part.
[0047]
In this case, the voltage V between the output terminals a and b of the inverter 4_abThus, when the semiconductor switching element 421 is turned on, the current flowing through the equivalent insulation resistance 201P, the capacitor 101a, and the CT 102 is as indicated by an arrow. The operation of detecting this current by the CT 102 and the leakage detection unit 110 is the same as in the case of FIG. 5 and FIG. Further, the operation at the time of electric leakage in the negative-side power supply line 63N can be easily imagined, and thus the description thereof is omitted.
Furthermore, in the first embodiment, the operation of the leakage detection units 110a, 110b, and 110c when the power supply lines 63P and 63N on the input side of the inverter 4 are leaked is substantially the same as that in FIG.
[0048]
In each of the above embodiments, the voltage source inverter 4 is activated before the vehicle is driven (for example, in a state where the AC contactor 5 is opened or the power of the electric motor 10 is not transmitted to the wheels (not shown)). By doing so, it is possible to detect in advance the leakage of the power supply line or the like on the input side or the output side of the inverter 4, thereby greatly improving the reliability of the electric system.
[0049]
FIG. 8 is a circuit configuration diagram showing a third embodiment of the present invention. This embodiment relates to a leakage detection system for detecting leakage of a DC power supply line of a DC-DC converter or an AC power supply line of an inverter in an electric system having a DC-DC converter for charging an auxiliary battery as shown in FIG. Is.
[0050]
In FIG. 8, reference numeral 91 denotes a two-stone forward type DC-DC converter shown in FIGS. The DC power supply line 901P on the positive side of the converter 91 is connected to the vehicle body 9 via a capacitor 101P, and the DC power supply line 901N on the negative electrode side is connected to the vehicle body 9 via a capacitor 101N.
CTs 102P and 102N are respectively connected between the capacitors 101P and 101N and the vehicle body 9, and current detection circuits 103P and 103N, low-pass filters 104P and 104N, leakage detection circuits 105P, 105N are sequentially connected, and the vehicle control device 8 is connected to the output side of the leakage detection circuits 105P and 105N.
In addition, 100C is a leakage detection device, and 110P and 110N are leakage detection units.
[0051]
In the DC-DC converter 91, high frequency AC voltage is generated in the high voltage winding 913P of the high frequency insulation transformer 913 by switching the semiconductor switching elements 911P and 911N at a high frequency of several tens of kHz or more as in FIGS. Let Then, a high-frequency AC voltage that is insulated and lowered is generated in the low-voltage winding 913 </ b> S, and this voltage is converted into a DC voltage by the rectifier 914 in FIG. 18, and then smoothed and supplied to the auxiliary battery 90. Further, the output voltage of the DC-DC converter 91 is changed by controlling the conduction ratio of the semiconductor switching elements 911P and 911N, and the charging current of the auxiliary battery 90 is controlled.
Since the operation of the DC-DC converter 91 is well known as described above, detailed description thereof is omitted.
The leakage detection operation in this embodiment is substantially the same as the operation of the fourth embodiment, as will be described later.
[0052]
FIG. 9 is a circuit configuration diagram showing a fourth embodiment of the present invention, and the same reference numerals are assigned to the same components as those in FIG.
8 is different from the embodiment of FIG. 8 in that the connection point of the capacitors 101P and 101N is connected to the vehicle body 9 in the leakage detecting device 100D shown in FIG. The current detection circuit 103, the low-pass filter 104, and the leakage detection circuit 105 are sequentially connected to the secondary side of the CT 102, and the vehicle control device 8 is connected to the output side, and the leakage detection unit 110 is shared. Is a point.
[0053]
Next, the operation of the embodiment of FIG. 9 will be described.
FIG. 10 shows the main part of FIG. 9 and is an operation explanatory diagram when there is no leakage from the DC power supply lines 901P and 901N. Note that both ends of the high-voltage winding 913P of the high-frequency isolation transformer 913 are terminals a and b.
In this case, the insulation resistance of the DC feed lines 901P and 901N with respect to the vehicle body 9 is infinite, and the current I passes through the capacitors 101P and 101N._cFlows, but the current I through CT102_lIs zero.
Voltage V at this time_ab, Current I_c, I_lIs the same as that of FIG._abThe waveform is a rectangular wave.
[0054]
FIG. 11 is a diagram showing a main part of FIG. 9 when the negative-electrode side DC power supply line 901N has a leakage current, and 201N is an equivalent insulation resistance showing a leakage part of the DC power supply line 901N.
In this case, the same voltage V as in FIG._abIs generated at both ends of the high-voltage winding 913P, and when the semiconductor switching element 911P is turned on, a current indicated by an arrow flows to the CT 102 through the capacitor 101P and the equivalent insulation resistance 201N.
[0055]
This current includes the voltage V_ab6 corresponding to the waveform of FIG. 6 flows through the equivalent insulation resistance 201N._rThis leakage current I_rIs represented by Equation 3 described above. In addition, V in Formula 3_dIs the DC input voltage of the DC-DC converter 91 (equal to the DC input voltage of the inverter 4)._dIs read as the resistance value of the equivalent insulation resistance 201N of the leakage section.
[0056]
In the CT 102 of FIG. 11, the I of FIG._cAs shown by voltage V_abCurrent corresponding to dv / dt at the time of rising and falling (I in FIG._cAnd I shown in Equation 3_rA combined current flows. Current I in FIG._lIs the current I flowing through CT102_cThe average value of which is I_rmIt is.
[0057]
Current I flowing through CT102_c9 is detected by the current detection circuit 103 in FIG. 9, is averaged by removing high-frequency components by the low-pass filter 104, and is input to the leakage detection circuit 105.
In the leakage detection circuit 105, the input current value (I in FIG._rm) Exceeds the specified value, it is determined that leakage has occurred, and a signal is sent to the vehicle control device 8 to perform necessary protective measures such as opening the DC contactor 92 and generating an alarm in FIG.
[0058]
The above description is the operation at the time of leakage of the DC power supply line 901N on the negative electrode side, but the operation is the same at the time of leakage of the DC power supply line 901P on the positive electrode side.
Further, in the third embodiment shown in FIG. 8, the operations by the CT 102P, 102N and the leakage detection units 110P, 110N when the DC power supply lines 901P, 901N are leaked are substantially the same as described above. Description is omitted.
[0059]
Next, FIG. 12 is an explanatory diagram of the main part when the B-phase power supply line 64b on the output side of the inverter 4 (semiconductor switch unit 42) is leaked in the fourth embodiment. In FIG. 12, 201b is an equivalent insulation resistance of the leakage part.
In FIG. 12, two arms of the A phase and the B phase among the three phases of the semiconductor switch unit 42 are shown as in FIG. Moreover, although all the three-phase semiconductor switching elements of the semiconductor switch unit 42 are connected in reverse parallel to the free-wheeling diodes, these are not shown.
[0060]
When electric leakage occurs in the power supply line 64b, the semiconductor switching element 424 of the inverter 4 and the semiconductor switching element 911P of the DC-DC converter 91 are turned on, thereby passing through the capacitor 101P and the equivalent insulation resistance 201b as shown by the arrows in FIG. Leakage current. This current is detected by the CT 102, and the subsequent leakage detection unit 110 performs the detection operation in the same manner as described above. Since the operation when the A-phase power supply line 64a of the inverter 4 is leaked or when the remaining one-phase (C-phase) power supply line 64c is easily leaked, the description is omitted.
Furthermore, in the third embodiment, when the power supply lines 64a, 64b, and 64c on the output side of the inverter 4 are leaked, the CTs 102P and 102N and the leak detection units 110P and 110N detect the leak, and the operation Is substantially the same as in FIG.
[0061]
In the third and fourth embodiments, before driving the automobile (for example, in a state where the AC contactor 5 is opened or the power of the electric motor 10 is not transmitted to the wheels (not shown)), the DC-DC converter 91, and further, by starting the inverter 4, it is possible to detect in advance a leakage of a current-carrying part such as a power supply line, thereby greatly improving the reliability of the electrical system.
[0062]
【The invention's effect】
As described above, according to the present invention, the AC output voltage of the inverter for driving the vehicle or the AC voltage generated in the winding of the insulation transformer included in the DC-DC converter is used as the power source of the leakage detection device. The effect can be expected.
(1) A dedicated power source for the earth leakage detection device is not required, and the number of parts, the circuit configuration can be simplified, and the price can be reduced as compared with the prior art.
(2) Since the output voltage of the inverter or the voltage generated by the insulation transformer of the DC-DC converter is used as the power supply voltage, the operation reliability is high.
(3) Leakage detection can be performed in advance by starting an inverter or a DC-DC converter before driving an automobile, and a highly reliable electrical system can be provided.
[0063]
In addition, although the said description assumes the case where a secondary battery is used as vehicle-mounted DC power supply, when using DC power supplies other than a secondary battery, for example, an electrolytic capacitor, an electric double layer capacitor, a fuel cell, a rectifier, etc. The present invention can also be applied to.
Furthermore, the present invention is also applicable to a hybrid vehicle having an electric drive system equipped with a high-voltage on-vehicle DC power source.
[Brief description of the drawings]
FIG. 1 is a circuit configuration diagram showing a first embodiment of the present invention.
FIG. 2 is a circuit configuration diagram showing a second embodiment of the present invention.
FIG. 3 is a diagram showing a main part of FIG. 2 at the time of non-leakage.
4 is an operation waveform diagram of FIG. 3;
FIG. 5 is a diagram showing a main part of FIG. 2 at the time of electric leakage on the output side of the inverter.
6 is an operation explanatory diagram of FIG. 5. FIG.
7 is a diagram showing a main part of FIG. 2 at the time of electric leakage on the input side of the inverter.
FIG. 8 is a circuit configuration diagram showing a third embodiment of the present invention.
FIG. 9 is a circuit configuration diagram showing a fourth embodiment of the present invention.
10 is a diagram showing a main part of FIG. 9 at the time of non-leakage.
FIG. 11 is a diagram showing a main part of FIG. 9 at the time of electric leakage of the DC power supply line of the DC-DC converter.
FIG. 12 is an operation explanatory diagram at the time of electric leakage on the output side of the inverter in the fourth embodiment of the present invention.
FIG. 13 is a circuit configuration diagram of an electric system in an electric vehicle or the like.
FIG. 14 is a circuit configuration diagram of a leakage detection system as a first conventional technique.
15 is an operation explanatory diagram at the time of electric leakage of the positive electrode side feeding line in FIG. 14;
16 is an operation explanatory diagram at the time of electric leakage of the negative electrode side power supply line in FIG. 14;
FIG. 17 is a circuit configuration diagram of another electric system in an electric vehicle or the like.
18 is a circuit configuration diagram of the DC-DC converter in FIG.
[Explanation of symbols]
1: Main battery
2P, 2N: fuse
3: DC contactor
4: Inverter
41: Input capacitor
42: Semiconductor switch part
5: AC contactor
61P, 61N, 62P, 62N, 63P, 63N, 64a, 64b, 64c, 901P, 901N: Feed line
8: Vehicle control device
9: Body
90: Auxiliary battery
91: DC-DC converter
910: Capacitor
911P, 911N: Semiconductor switching element
912P, 912N, 914a, 914b: diode
913: High frequency isolation transformer
913P: High voltage winding
913S: Low voltage winding
914: Rectifier
915: Current smoothing reactor
916: Current smoothing capacitor
10: Vehicle drive motor
100A, 100B, 100C, 100D: Leakage detection device
101a, 101b, 101c, 101P, 101N: capacitors
102, 102a, 102b, 102c, 102P, 102N: CT
103, 103a, 103b, 103c, 103P, 103N: current detectors
104, 104a, 104b, 104c, 104P, 104N: Low-pass filter
105, 105a, 105b, 105c, 105P, 105N: Leakage detection circuit
110, 110a, 110b, 110c, 110P, 110N: leakage detector
201b, 201P, 201N: equivalent insulation resistance

Claims (14)

In an automotive electrical system in which a vehicle drive motor is driven via an inverter with electric power from an in-vehicle DC power source, and an energization unit including a power supply line to the motor is electrically insulated from a vehicle body.
An automobile leakage detection system comprising: a leakage detection device using an AC voltage generated on the AC output side of the inverter as a power supply; and detecting leakage from the energization unit to the vehicle body by the leakage detection device. In the automobile electric leakage detection system according to claim 1,
The leakage detection device includes:
A series circuit of a capacitor and a current detector connected between the AC output side of the inverter and the vehicle body,
An electric leakage detection system for an automobile, wherein electric leakage of the energization unit is detected from a current value flowing through the current detector. In the vehicle electric leakage detection system according to claim 1 or 2,
The leakage detection device includes:
A series circuit comprising a capacitor connected in a star shape on the AC output side of the inverter, and a current detector connected between the neutral point and the vehicle body,
An electric leakage detection system for an automobile, wherein electric leakage of the energization unit is detected from a current value flowing through the current detector. In the automobile electric leakage detection system according to any one of claims 1 to 3,
An automobile leakage detection system, wherein the inverter is activated before the automobile is driven to detect leakage in the energization unit. The electric power of the first in-vehicle DC power source is supplied to the second in-vehicle DC power source via the insulation type DC-DC converter, and the vehicle driving motor is driven from the first in-vehicle DC power source through the inverter. In an automobile electrical system in which a current-carrying part including a power supply line is electrically insulated from a vehicle body,
An automobile leakage detection system comprising: a leakage detection device using an AC voltage generated in the DC-DC converter as a power source, and detecting leakage from the energization unit to the vehicle body by the leakage detection device. In the automobile electric leakage detection system according to claim 5,
The leakage detection device includes:
A leakage detection system for an automobile, characterized in that an AC voltage generated in a winding on the first in-vehicle DC power supply side of an insulation transformer included in the DC-DC converter is used as a power supply. In the automobile electric leakage detection system according to claim 6,
The leakage detection device includes:
A series circuit of a capacitor and a current detector connected between the winding on the first in-vehicle DC power supply side of the insulation transformer and the vehicle body;
An electric leakage detection system for an automobile, wherein electric leakage of the energization unit is detected from a current value flowing through the current detector. In the automobile electric leakage detection system according to claim 6 or 7,
The leakage detection device includes:
A plurality of capacitors connected in series between both ends of the winding on the first in-vehicle DC power supply side of the insulation transformer, and a current detector connected between an interconnection point of these capacitors and the vehicle body; With
An electric leakage detection system for an automobile, wherein electric leakage of the energization unit is detected from a current value flowing through the current detector. In the automobile electric leakage detection system according to any one of claims 5 to 8,
An automobile electric leakage detection system which activates the DC-DC converter to detect electric leakage of the energization unit before driving the automobile. In the electric leakage detection system for automobiles according to any one of claims 2, 3, 4, 7, 8, and 9,
An automobile electric leakage detection system that detects an electric current flowing through the current detector through a low-pass filter and detects the occurrence of electric leakage when the detected current value exceeds a specified value. In the automobile electric leakage detection system according to any one of claims 1 to 4, 10,
A vehicle earth leakage detection system characterized in that the rated voltage of the in-vehicle DC power supply is 50 V or more. In the automobile electric leakage detection system according to any one of claims 1 to 4, 10, and 11,
An on-vehicle DC power supply is any of a secondary battery, an electrolytic capacitor, an electric double layer capacitor, a fuel cell, and a rectifier. The vehicle leakage detection system according to any one of claims 5 to 10, wherein the rated voltage of the first in-vehicle DC power supply is 50 V or more. In the automobile electric leakage detection system according to any one of claims 5 to 10 and 13,
A vehicle electric leakage detection system, wherein the first in-vehicle DC power source is any one of a secondary battery, an electrolytic capacitor, an electric double layer capacitor, a fuel cell, and a rectifier.

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