JP3227971B2 - Earth leakage detection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric leakage detector for use in a vehicle powered by a DC power source separated from a body ground such as an electric car or a train.

[0002]

2. Description of the Related Art FIGS. 3 and 4 show the structure of a conventional leakage detecting device. 3 and 4, reference numeral 21 denotes a DC power supply composed of a battery or the like. 22 and 23 are resistors, 2
4 is a leakage detection resistor, 25 is a ground,
And grounded separately. 26 and 27 are comparators,
Reference numerals 28 and 29 denote comparison voltages for determining electric leakage. Reference numeral 30 denotes an OR circuit, reference numeral 31 denotes an earth leakage resistance, and reference numeral 32 denotes a human body resistance. Reference numerals 33 and 34 denote positive and negative outputs of the DC power supply 21, respectively, and reference numeral 35 denotes a leakage determination output. FIG. 4 shows a case where an electric leakage has occurred. Reference numeral 36 denotes a motor in which an electric leakage has occurred.
7, 38, 39 and 40 are switching elements, and 41 is a leakage resistance generated in the motor 36.

Next, the operation of the above conventional example will be described. Generally, the voltage used for electric vehicles is 200 to 3
It is a DC voltage of 00 V, and is in a floating state separated from the body ground of the vehicle so that a human body does not receive an electric shock even when directly connected to one of the power supply lines.
In FIG. 3, even if the human body contacts the positive side of the DC power supply 21, when the resistance value r of the earth leakage resistor 31 is "∞" and no earth leakage occurs, there is no path through which the current flows, and Will not be shocked. When the resistance value Z of the human body resistor 32 and the leakage resistance 31 are “３１”, the leakage detection resistance 2
4, no current flows, so that no voltage is generated across the leakage detection resistor 24.

Here, a case where the insulation breakdown occurs on the negative side of the DC power supply 21 and the resistance value r of the earth leakage resistance 31 becomes small will be described. + DC power supply 21
R ₁ and R ₂ are set larger than R _S and r, where B volts, the resistances of the resistors 22 and 23 and the leakage detection resistor 24 are R ₁ , R ₂ and R _S , respectively. In this case, as shown in FIG. 3, the resistor 22, the current i ₁ flowing through the leakage detection resistor 24 and the leak resistance _{31, i 1 = + B / (} R 1 + R S + r) ··· (1) it becomes. Therefore, when the voltage across the leakage detection resistor 24 and _{V a V a = R S ×} i 1 ··· (2).

When the voltage V ₁ corresponding to the leakage current to be detected is compared with the comparison voltage 28 of the comparator 26, the output of the comparator 26 becomes the leakage determination output.

If the leakage occurs on the positive side of the DC power supply 21, the voltage across the leakage detection resistor 24 becomes negative. Therefore, the output of the OR circuit 30 that takes the OR of the outputs of the comparators 26 and 27 is the leakage determination output.

[0007]

However, the above-described conventional electric leakage detecting device can detect an electric leakage that is constantly occurring, but as shown in FIG.
In the case where the motor 36 or the like driven by No. 1 has a short circuit, there is a problem that the short circuit cannot be detected.

That is, since the motor 36 normally switches at a frequency of 10 kHz or more, electric leakage occurs when power is supplied to the motor 36 and the switching elements 37, 38, 3
Occurs only when 9 and 40 are ON. In the conventional leak detection device, it was difficult to detect a leak corresponding to this timing. As described above, the conventional leakage detection device has a problem that the leakage cannot be detected in synchronization with the timing at which the leakage occurs.

The present invention eliminates the above-mentioned conventional problems, and provides an excellent leakage detection device capable of reliably detecting a leakage in synchronization with a timing at which a leakage occurs.

[0010]

Means for Solving the Problems The present invention, in order to achieve the above object, a leakage detecting unit for detecting the leakage of the direct-current power supply separated from the body ground of the vehicle is mounted on a vehicle, a leakage portion Multiple types of timing connected to DC power supply
A timing extraction unit that extracts a timing at which the DC power is applied to the leakage unit, and a leakage determination synchronization unit that determines leakage in synchronization with the output of the timing extraction unit. It is a thing.

[0011]

The present invention has a configuration as described above, and extracts a timing at which a leakage can be detected, and detects a leakage in synchronization with this timing. It is also possible to reliably detect intermittent leakage.

[0012]

1 and 2 show an embodiment of the present invention.
It will be explained together. FIG. 1 shows the configuration of the first embodiment of the present invention. In FIG. 1, reference numeral 1 denotes a high-voltage DC power supply, which includes a 200-300 V battery or the like. Reference numerals 2 and 3 are resistors, and reference numeral 4 is a leakage detection resistor. Reference numeral 5 denotes a ground, which is separated from the DC power supply 1 and grounded. Reference numerals 6 and 7 denote comparators, reference numerals 8 and 9 denote comparison voltages for judging leakage, respectively, and reference numeral 10 denotes an OR circuit for ORing the outputs of the comparators 6 and 7. Reference numeral 11 denotes an electric leakage determination synchronization unit that determines electric leakage at the timing of detecting electric leakage. Reference numeral 12 denotes a leakage determination output that is output when a leakage occurs. 13 is a timing extracting unit, 14 is a motor, 15, 16, 17 and 18 are transistors for driving the motor 14, and 19 is a control unit for controlling the driving of the motor 14. Reference numeral 30 denotes a leakage detection unit,
It comprises a leakage detection resistor 4, a ground 5, comparators 6, 7, comparison voltages 8, 9, and an OR circuit 10.

Next, the operation of the first embodiment will be described. When a winding or the like inside the motor 14 is short-circuited to the ground 5, the leakage occurs only when the transistors 15 to 18 that drive the motor 14 are ON. The timing when the transistors 15 to 18 are turned on is extracted by the timing extracting unit 13. In the embodiment shown in FIG. 1, the timing extracting unit 13 is configured by an OR circuit that takes the sum of the base signals of the transistors 15 to 18, and determines the timing at which the motor 14 is leaked by the base signals of the transistors 15 to 18. Output signal.

In the same manner as in the prior art, the leakage detection resistor 4
In comparator 6 or comparator 7 the output voltage of, when compared with voltages V ₁ or the voltage V ₂ corresponding to the leakage current to be detected can be detected leakage, the sum output of the comparator 6 and 7 in the OR circuit 10 The output of the OR circuit 10 indicates whether or not there is a leakage. The leakage determination synchronization unit 11 is configured by, for example, an AND circuit, and determines the leakage based on the output of the OR circuit 10 when the timing extraction unit 13 outputs. Therefore, the output of the leakage determination synchronization unit 11 becomes the leakage determination output 12.

As described above, according to the first embodiment,
Transistors 15-18 driving motor 14 are O
The timing at the time of N is extracted by the timing extracting unit 13. The output of the timing extracting unit 13 causes the electrical leakage determination synchronization unit 11 to determine whether or not electrical leakage has occurred. If you have
Leakage can be detected accurately.

[0016] Even if the leakage occurs steadily instead of in a switching manner, it is possible to detect the leakage by determining the output of the OR circuit 10.

Next, a second embodiment of the present invention will be described. FIG. 2 shows the configuration of the second embodiment of the present invention. About the same composition as a 1st example, the same numerals are given and explanation is omitted. In FIG. 2, reference numeral 20 denotes a sample-and-hold circuit that holds the voltage of the leakage detection resistor 4 when the timing extracting unit 13 outputs.

Next, the operation of the second embodiment will be described. In the same manner as in the operation of the first embodiment, when a signal indicating the timing at which the motor 14 is leaking is output from the timing extracting unit 13, this output is sent to the sample hold circuit 20 together with the leak determining synchronization unit 11. Applied. As a result, even when the switching time interval of the motor 14 is short, the voltage of the leakage detection resistor 4 can be sampled and held at the time of the output of the timing extraction unit 13, so that sufficient responsiveness can be ensured and the leakage can be ensured Can be detected. Further, even when the time constant to be determined is longer than the switching time, it is possible to reliably detect the electric leakage by thinning out and detecting the sample and hold timing.

In the second embodiment, the sample-and-hold circuit 20 that samples and holds the voltage of the leakage detection resistor 4 is used, but instead of the sample-and-hold circuit 20, an analog-to-digital converter (AD) is used. Converter) can also be used. In this case, the output of the leakage detection resistor 4 is synchronized with the output of the timing
The same effect can be obtained by performing D conversion and detecting an electric leakage using the AD conversion value.

[0020]

As is clear from the above embodiment, the present invention extracts the timing at which the leakage can be detected, and detects the leakage in synchronization with this timing. In addition, there is an effect that it is possible to reliably detect intermittent leakage.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an electric leakage detection device according to a first embodiment of the present invention.

FIG. 2 is a configuration diagram of an electric leakage detection device according to a second embodiment of the present invention.

FIG. 3 is a configuration diagram of a conventional leakage detection device.

FIG. 4 is a configuration diagram showing a state in which a leakage has occurred in a conventional leakage detection device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 DC power supply 2, 3 resistance 4 Leakage detection resistance 5 Ground 6, 7 Comparator 8, 9 Comparison voltage 10 OR circuit 11 Leakage determination synchronization part 12 Leakage determination output 13 Timing extraction part 14 Motor 15, 16, 17, 18 Switching transistor 19 Control unit

Continuation of front page (58) Field surveyed (Int.Cl. ⁷ , DB name) B60L 3/00 G01R 31/02

Claims (2)

(57) [Claims] An electric leakage detection unit mounted on a vehicle and detecting an electric leakage of a DC power supply separated from a body ground of the vehicle, and a plurality of types of timers connected to the electric leakage unit and the DC power supply.
A timing extraction unit that extracts a timing at which the DC power is applied to the leakage unit, and a leakage determination synchronization unit that determines leakage in synchronization with the output of the timing extraction unit. Leak detection device. 2. A vehicle body mounted on a vehicle.
Leakage detection that detects leakage of the DC power supply separated from the
And the timing at which the DC power is applied to the earth leakage part.
The timing extraction unit to be extracted and the timing extraction unit
It is equipped with an earth leakage judgment synchronization unit that judges electric leakage in synchronization with output.
For example, the leakage detection unit is configured to output
A sample hook that samples and holds the leakage detection output signal
Leakage detection device equipped with a ground circuit .