JPH09140051A - Power supply equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent any burning accident caused by charging resistance in an early stage of charging by interrupting a DC power supply after detecting a current flowing through charging resistance with a current sensor and the detected current has exceeded a predetermined value for the point in time where the preset time has elapsed after turning on a DC power supply. SOLUTION: When a filter capacitor 4 and a chopper 5 are sound, any anomaly in the filter capacitor 4 or the chopper 5 can be easily judged by detecting a current flowing through a charging resistor 9 with a current sensor 10 at a point in time when a certain time has elapsed after the time predicted for reaching a predetermined voltage at the terminal of the filter capacitor 4 after closing a circuit breaker. Since any anomaly in the filter capacitor 4 or the chopper 5 can be detected by a current flowing to the charging resistor 9, the reliability of detecting the anomaly can be improved considerably. As a result, any burning loss of the charging resistor 9 caused by abnormal states such as the short-circuit of the filter capacitor 4 or chopper 5 can be definitely prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle auxiliary power supply device for converting electric power from a high-voltage DC overhead wire into low-voltage DC power or AC power, and more particularly to the initial stage of such a power supply device. It relates to a charging circuit.

[0002]

2. Description of the Related Art FIG. 3 is a simplified circuit diagram mainly showing an initial charging circuit of a conventional power supply device disclosed in Japanese Patent Laid-Open No. 5-64423. In the figure, 1 is a DC power source, 2
Is a circuit breaker, 3 is a DC reactor, 4 is a filter capacitor, 5 is a chopper, 6 is an inverter, 7 is a load, 8 is a switching element, 9 is a charging resistor for limiting an inrush current to the filter capacitor 4 at the time of initial charging, 17 is a charging resistor 9
Sensor for detecting the terminal voltage of the voltage sensor 11, voltage sensor 1
7 is a control circuit for operating the circuit breaker 2 according to the detection signal of 7.

Next, the operation will be described. When the circuit breaker 2 is turned on, the switching element 8 is turned off and a power supply voltage is applied to the filter capacitor 4 via the DC reactor 3 and the charging resistor 9. After detecting that the terminal voltage of the filter capacitor 4 has reached a predetermined voltage, the switching element 8 is turned on, the charging resistor 9 is short-circuited, and the filter capacitor 4 is charged only via the DC reactor 3. When the terminal voltage of the filter capacitor 4 further rises and the starting condition of the power supply device is established, the chopper 5 and the inverter 6 are operated to supply AC power to the load 7. By the way, when the filter capacitor 4 is short-circuited or the chopper 5 is ground-faulted, the terminal voltage of the filter capacitor 4 does not rise and a short-circuit current flows through the charging resistor 9. In such a case, when the filter capacitor 4, the chopper 5 and the inverter 6 are sound, when a certain time has elapsed from the time when the terminal voltage of the filter capacitor 4 is expected to reach a predetermined voltage after the circuit breaker 2 is turned on,
If the terminal voltage of the charging resistor 9 detected by the voltage sensor 17 is higher than a predetermined voltage, it is determined that an abnormality has occurred in the charging circuit or the chopper 5, and the breaker 2 is opened. In this way, the charging resistor 9 is prevented from burning due to the short-circuit current.

[0004]

SUMMARY OF THE INVENTION In a conventional power supply,
Since the initial charging circuit has the above-mentioned configuration, when the filter capacitor is short-circuited or the chopper is grounded, the circuit protection is practically limited by limiting the duration of the short-circuit current flowing through the charging resistor. Equal to going. However, in an application such as a vehicle auxiliary power supply device in which the fluctuation range of the input voltage is large, the fluctuation of the charging current of the filter capacitor 4 is also large. It becomes difficult to determine the charging current of the filter capacitor, which may result in an erroneous short circuit determination.

The present invention has been made to solve the above problems, and an object thereof is to accurately and promptly detect an abnormality when a filter capacitor is short-circuited or a ground fault occurs in a chopper. It is to realize a power supply device using an initial charging circuit that can be detected.

[0006]

Means for Solving the Problems When a current flowing through a charging resistor is detected by a current sensor, and the magnitude exceeds a predetermined value at a point of time when a predetermined set time has passed after a DC power supply is turned on,
The DC power supply is opened. Further, a fuse element is connected to the filter capacitor, and a sensor element including a resistor having a high electric resistance and a current sensor for detecting a current flowing through the resistor is provided in parallel with the series connection body of the fuse element and the filter capacitor. When the detected current of the sensor element exceeds a predetermined magnitude when a predetermined set time elapses after the DC power is turned on, the DC power supply is opened.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiment 1 FIG. Hereinafter, a first embodiment of the present invention will be described with reference to the drawings. In the figure, those parts which are the same as or correspond to those in FIG. 3, which is a simplified circuit diagram mainly showing the initial charging circuit in the conventional power supply device described above, are designated by the same reference numerals, and the description of the functions and operations will be repeated. The part is omitted. FIG. 1 is a simplified circuit diagram showing a power supply device according to the present invention mainly including an initial charging circuit. In the figure, 10 is a current sensor for detecting the current of the charging resistor 9, and 11 is a control circuit. Next, the operation will be described. When the circuit breaker 2 is turned on while the filter capacitor 4 is short-circuited or the chopper 5 is ground-faulted, the initial charging circuit becomes the LR circuit, so the current is limited by the input reactor 3 and the charging resistor 9 and the current flowing in the circuit. Approaches a current determined only by the charging resistor 9 with the passage of time. On the other hand, when the filter capacitor 4 and the chopper 5 are in a healthy state, the circuit is an LRC circuit and the resistance value of the charging resistor 9 is large and satisfies the non-oscillating circuit condition. The maximum current is reached, after which the current decays rapidly.

When the filter capacitor 4 and the chopper 5 are sound, the current sensor 10 causes the current sensor 10 to detect a certain time after the terminal voltage of the filter capacitor 4 is expected to reach a predetermined voltage after the circuit breaker 2 is turned on. By detecting the current flowing through the charging resistor 9, the abnormality of the filter capacitor 4 or the chopper 5 can be easily determined.
In this way, since the abnormality of the filter capacitor 4 or the chopper 5 is detected by the current flowing through the charging resistor 9, the abnormality detection reliability is significantly improved. In particular, it is possible to reliably prevent burning of the charging resistor 9, which is highly likely to be fatally damaged due to an abnormality such as a short circuit of the filter capacitor 4 or the chopper 5.

In the above description, after the circuit breaker 2 is turned on,
Although the abnormality of the filter capacitor 4 or the chopper 5 of the power supply device is determined by the detection current of the current sensor 10 after a lapse of a certain time, the square value of the detection value of the current sensor 10 is integrated over time to obtain the power supply device. The abnormality may be determined and the charging resistor 9 may be operated so as to be prevented from being burnt out. The amount of heat generated by the charging resistor 9 is approximately proportional to the square of the current value. Moreover, since the allowable heat generation amount per unit time in the charging resistor 9 is almost uniquely determined by the specifications of the resistor used and the installation environment, the square value of the detected value of the current sensor 10 is integrated over time at an appropriate time interval. By releasing the circuit breaker 2 when the obtained time integrated value exceeds the preset allowable value, the reliability in detecting the abnormality of the power supply device is further improved, and the burnout of the charging resistor 9 can be reliably prevented.

In each of the above embodiments, the power supply device having the chopper between the filter capacitor and the inverter has been described as an example, but the same effect can be obtained even when the power supply device does not use the chopper. Needless to say.

Embodiment 2. The power supply device according to the first embodiment is configured to detect the abnormality of the power supply device by the current flowing through the charging resistor 9. However, as shown in FIG. 2, a filter capacitor with a fuse having a current cutoff function as a filter capacitor. 14, a resistor 15 having a high resistance and a current sensor 16 for detecting a current flowing through the resistor 15 are provided in parallel with the filter capacitor 14, and an abnormality of the filter capacitor 4 or the chopper 5 is detected by the current detected by the current sensor 16. Even if the detection is performed, the same abnormality detection as that of the power supply device according to the first embodiment can be performed.

[Brief description of the drawings]

FIG. 1 is a simplified circuit diagram of a power supply device according to a first embodiment of the present invention.

FIG. 2 is a simplified circuit diagram of a power supply device according to a second embodiment of the present invention.

FIG. 3 is a simplified circuit diagram of a conventional power supply device.

[Explanation of symbols]

1 DC power supply 2 Circuit breaker 3
DC reactor 4 Filter capacitor 5 Chopper 6
Inverter 8 Switching element 9 Charging resistor 11
Control circuit

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location H02M 3/135 H02M 3/135 CY

Claims (2)

[Claims] 1. A filter capacitor connected between a DC power supply and an inverter element, a DC reactor connected between the DC power supply and the filter capacitor, and a DC capacitor connected between the DC reactor and the filter capacitor. An initial charging circuit in which a switching element that becomes non-conductive when the terminal voltage of the filter capacitor does not reach a predetermined voltage and a charging resistor that limits the current when the switching element is non-conductive to a predetermined magnitude are connected in parallel. In a power supply device having, a current sensor for detecting a current flowing through the charging resistor is provided, and a current value detected by the current sensor has a predetermined magnitude when a predetermined set time has elapsed after the DC power supply is turned on. The power supply device is characterized in that the DC power supply is opened when exceeding the limit. 2. A filter capacitor connected between a DC power source and an inverter element, a DC reactor connected between the DC power source and the filter capacitor, and a DC capacitor connected between the DC reactor and the filter capacitor. An initial charging circuit in which a switching element that becomes non-conductive when the terminal voltage of the filter capacitor does not reach a predetermined voltage and a charging resistor that limits the current when the switching element is non-conductive to a predetermined magnitude are connected in parallel. In a power supply device having: a fuse element capable of interrupting a current when a predetermined current flows, is connected in series with the filter capacitor, and a resistor having a high electric resistance and a current flowing through the resistor are detected. A sensor element composed of a current sensor for connecting the fuse element and the filter capacitor in series. It is connected in parallel with the body, and when the detected current of the sensor element deviates from a predetermined range when a predetermined set time elapses after the DC power is turned on, the DC power is opened. Power supply.