KR20210047735A - DC Short Circuit System for Low Voltage DC equipment - Google Patents

Abstract

The present invention relates to a short circuit test facility for DC equipment, which easily configures test equipment required for a short circuit test of a DC device using an electric energy storage device called a capacitor, a DC charger, and a semiconductor switch without using huge expensive equipment such as a short circuit generator. It is possible to set the required test voltage in a wide range by using a constant power type or constant current type charger. The required short-circuit current and voltage can construct a short-circuit test facility by composing an energy storage device, a circuit, and a circuit module in series or in parallel.

Description

Short circuit test equipment for low voltage DC equipment {DC Short Circuit System for Low Voltage DC equipment}

The present invention is for a short-circuit test of a safety protection device using electrical energy from a battery or a rectified DC source such as a DC circuit breaker, a DC switch, and a fuse. It relates to circuits and configurations including devices for supplying and shutting off.

Short circuit performance of relevant devices in response to the increase in production and use of DC circuit breakers, DC switches and DC fuses used for safety and protection of various devices or facilities due to the increase in electric vehicles, solar power generation, and medium and low voltage DC distribution facilities. It is necessary to test and verify.

In general, short-circuit tests of DC or AC devices have been performed using a short-circuit generator with a large capacity. However, the short-circuit generator has a capacity of at least several hundred MVA, which entails a lot of time and cost to build the facility. In addition, a lot of electrical energy is required for initial driving of the short circuit generator, leading to consumption of a large amount of electrical energy during frequent driving. Since the short-circuit generator rectifies AC power to obtain DC power, it is not a smooth power source such as pure DC power as shown in FIG. 1, but it involves voltage (10) and current (20) ripple generated from the rectifier. It is different from a pure DC power source in which a DC device is used. This may include a characteristic error due to voltage ripple in the test result when performing a short circuit test.

Therefore, it is necessary to test the DC equipment to be tested in the same DC source as the operating environment, and alternative equipment with low cost and equipment with low power consumption are required.

Therefore, the present invention was conceived to solve the above-described problems, and an object of the present invention is to minimize the cost of building short-circuit facilities as well as minimize power consumption even in frequent tests, and suitable for the use environment of DC equipment, DC motors. The purpose is to provide short-circuit test equipment for use.

The objects of the present invention are not limited to the objects mentioned herein, and other objects not mentioned will be clearly understood from the following description.

First, summarizing the features of the present invention, a short circuit test facility for a DC device according to an aspect of the present invention for achieving the above object includes: a charger for receiving an AC power and outputting a preset voltage; And a test circuit having both ends of the input side connected between the other end of the forward diode connected to the anode of the charger and the cathode of the charger, the test circuit being connected to both ends of the input side and charging with the preset voltage from the charger. Energy storage device; A semiconductor switch for outputting a short-circuit current from an output of the energy storage device to an object under test through an output-side anode; And a freewheeling diode connected in a reverse direction between the positive end of the output side and the negative end of the charger.

The short-circuit test facility further includes a dump resistor and a switch connected in parallel with the energy storage device.

The short-circuit test facility further includes a short-circuit current adjusting resistor connected to the positive end and connected in series to the test article.

The short-circuit current adjustment resistor adjusts the current so that the short-circuit current output to the product under test through the semiconductor switch does not exceed the rating of the semiconductor switch.

The semiconductor switch may be an Insulated Gate Bipolar Transistor (IGBT), or a thyristor including an integrated gate-commutated thyristor (IGCT) or a gate turn-on thyristor (GTO).

The product under test may include a circuit breaker or a fuse of a DC device.

When the breaker is blocked or the fuse cannot be blown at a predetermined time, a predetermined control device may turn off the semiconductor switch.

The charger may charge a capacitor or a capacitor stack of the energy storage device in a constant power type, a constant current type, or a phase control rectification method.

The capacitor or capacitor stack of the energy storage device may include a super capacitor, an electrolytic capacitor, or an energy storage film capacitor.

A plurality of test circuits may be configured in parallel, and a plurality of test circuits are connected in parallel between the charger and the test product to correspond to the required current of the test product. The corresponding short-circuit current can be output.

It is possible to configure a plurality of test circuits in series or in parallel using a MCCB (Molded Case Circuit Breaker) type switch to correspond to the required voltage or current of the EUT.

According to the short-circuit test facility for a DC device of the present invention, it is possible to perform a short-circuit current test of a medium-low voltage DC device using a small amount of power without using a large-capacity short-circuit generator for a short circuit test of an electric device used in a DC circuit.

Accordingly, it is possible to easily and at low cost to construct a DC short-circuit facility, and to minimize the use of power required in a short-circuit test. In addition, since a capacitor is used as an energy storage device, there is an effect that the test voltage can be adjusted very flexibly according to the rated voltage of the device under test (subject) in some cases.

In addition, the size of the short-circuit test current can be adjusted by adjusting the number of circuits between the energy storage device and the EUT to the test current, and in the case of a fuse used to protect the battery circuit of an electric vehicle, various voltage ratings (DC300V ~ DC1, 000V or more) can be easily responded to, so there is an effect of reducing cost by reducing the configuration of equipment and charging time and test time according to product development.

The accompanying drawings, which are included as part of the detailed description to aid in understanding of the present invention, provide embodiments of the present invention and describe the technical spirit of the present invention together with the detailed description.
1 is a fuse short-circuit test waveform using a general short-circuit generator.
2 is a waveform of a charging current 30 and a charging voltage 40 of a charger storing energy required for a short-circuit test in an energy storage device (capacitor type) in the present invention.
3 is a circuit diagram of a short circuit test facility for a DC device including only two circuits of the present invention.
4 is a view for explaining a case in which the short-circuit current capacity is increased by parallel connection of the test circuit 50 of the present invention.
5 is a diagram for explaining a case in which the short-circuit current and test voltage capacity are increased by connecting the test circuit 50 in series and parallel according to the present invention.
6 shows a switch 80 for a series-parallel configuration of the test circuit 50 of the present invention.
7 is an example in which the switch 80 of FIG. 6 is used in a parallel circuit configuration of the test circuit 50 of the present invention.
8 is an example in which the switch 80 of FIG. 6 is used in a series circuit configuration of the test circuit 50 of the present invention.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings. In this case, the same components in each drawing are indicated by the same reference numerals as possible. In addition, detailed descriptions of already known functions and/or configurations will be omitted. In the following, a portion necessary for understanding an operation according to various embodiments will be mainly described, and descriptions of elements that may obscure the subject matter of the description will be omitted. In addition, some elements of the drawings may be exaggerated, omitted, or schematically illustrated. The size of each component does not fully reflect the actual size, and therefore, the contents described herein are not limited by the relative size or spacing of the components drawn in each drawing.

In describing the embodiments of the present invention, when it is determined that a detailed description of a known technology related to the present invention may unnecessarily obscure the subject matter of the present invention, a detailed description thereof will be omitted. In addition, terms to be described later are terms defined in consideration of functions in the present invention, which may vary according to the intention or custom of users or operators. Therefore, the definition should be made based on the contents throughout the present specification. The terms used in the detailed description are merely for describing the embodiments of the present invention, and should not be limited by any means. Unless explicitly used otherwise, expressions in the singular form include the meaning of the plural form. In the present description, expressions such as "comprising" or "feature" are intended to refer to certain features, numbers, steps, actions, elements, some or combination thereof, and one or more It should not be construed to exclude the presence or possibility of other features, numbers, steps, actions, elements, any part or combination thereof.

In addition, terms such as first and second may be used to describe various components, but the components are not limited by the terms, and the terms are used to distinguish one component from other components. Is only used.

2 is a waveform of a charging current 30 and a charging voltage 40 of a charger storing energy required for a short-circuit test in an energy storage device (capacitor type) in the present invention. That is, as the charging current 30 flows from the charger to the energy storage device (capacitor type), the charging voltage 40 gradually increases to a predetermined DC (Direct Current) voltage, and when charging is completed, the charging voltage 40 is Maintain a predetermined DC voltage.

3 is a circuit diagram of a short circuit test facility for a DC device according to the present invention.

Referring to FIG. 3, the short circuit test facility for a DC device of the present invention includes a charger 200 receiving an input of a three-phase AC power supply 100, and a positive end of the input side between the two electrodes 210 and 220 of the charger 200. And one or more test circuits 50 connected to the cathode end. The anode 210 of the charger 200 may be connected to the anode end of the test circuit 50 through the forward diode 250.

The test circuit 50 includes an energy storage device 300 having an equivalent internal resistance 330, a dump resistance 310, a switch 320, a semiconductor switch 400, and a free wheeling diode 500. Includes. The short-circuit current adjustment resistor 700 and the EUT 800 are connected in series, and the positive and negative ends of the output side of the test circuit 50 are connected to both ends thereof. In consideration of the line impedance 550 between the test circuit 50 and the product under test 800, a line impedance 550 is included between the positive end of the output side of the test circuit 50 and the short-circuit current adjustment resistor 700.

In FIG. 3, the charger 200 controls the current charging the energy storage device 300 such as a capacitor, and the required DC voltage 40 (in the case of a capacitor, energy is charged in proportion to the square of the charged voltage. ) Is charged up to the set DC voltage 40 according to the setting. Therefore, the voltage required for the short-circuit current can be arbitrarily set, and the energy required for one short-circuit test (E=VxIxT, E is the energy, V is the test voltage, I is the test short-circuit current, and T is the time the short-circuit current flows). Is to use the energy charged in the energy storage device 300 such as a capacitor. The energy required in the short-circuit test is in accordance with the test standard, and the size of the capacitor, etc., is required so that the voltage drop of the energy storage device 300 meets the regulations due to the energy consumed by the short-circuit test, and the size of the short-circuit current is adjusted. The DC voltage 40 to be charged is determined in consideration of the voltage drop caused by the resistor 700, the semiconductor switch 400, the equivalent internal resistance 330 of the energy storage device 300, and the line impedance 550.

At this time, when charging two or more energy storage devices 300 of the circuits 50 using one charger 200, a diode 250 is inserted between each energy storage device 300 and the charger 200. , Even when the charging time of the energy storage device 300 is different according to the characteristics and circuit conditions of the energy storage device 300, the current is reversed until the energy storage device 300 of the lower voltage is charged to a set value. In addition, it has a function of electrically separating the charger 200 from the energy storage device 300 after charging is completed. In addition, as the energy storage device 300, in the case of a capacitor, a dump resistor 310 and a switch 320 are connected in parallel with the capacitor so that energy can be dumped (discharged) in consideration of high voltage safety and the lifetime of the capacitor. Make up. The freewheeling diode 500 connected in the opposite direction to the output side pole is configured to allow energy stored in the inductance of the test line 600 to flow, and serves to protect the semiconductor switch 400. The energy storage device 300 may be discharged when necessary according to the control of the switch 320 of the control device (not shown).

In the short circuit test facility for a DC device of the present invention using an energy storage device 300 such as a capacitor in FIG. 3, the AC power supplied from the three-phase AC power supply 100 is converted to DC, and constant power is used by the charger 200. As a result, energy is charged with a voltage required for the capacitor, which is the energy storage device 300. In addition to the constant power type, the charger 200 may charge a capacitor or a capacitor stack, which is the energy storage device 300 by a constant current type or a phase control rectification method. The energy thus charged is applied to the current control resistor 700 and the test product 800 through a semiconductor switch 400 such as an equivalent series resistance (esr) 330 and an Insulated Gate Bipolar Transistor (IGBT). A short-circuit current required for the product under test 800 is formed. When the short-circuit current exceeds the rating of the semiconductor switch 400, the resistance value of the current control resistor 700 is appropriately adjusted and applied.

By this short-circuit current, the circuit breaker and fuse, etc., of the DC device under test (800) are blocked or blown to ensure successful performance verification, or if the designed performance is insufficient and the breaker or fuse cannot be blown, the specified time The semiconductor switch 400 is turned off according to the control of the control device (not shown) to cut off the circuit, thereby preventing the consumption of more than necessary stored energy. The control device (not shown) may generate a control signal for controlling the on/off of the semiconductor switch 400.

4 is a view for explaining a case in which the short-circuit current capacity is increased by parallel connection of the test circuit 50 of the present invention.

As shown in FIG. 4, when the short-circuit current is large and it is difficult to supply the short-circuit current to one test circuit 50, two or more test circuits 50 may be connected in parallel 60 to increase the short-circuit capacity. The short-circuit current required as described above can be constructed as a parallel circuit module by configuring the test circuit 50 with a plurality of parallel 60.

5 is a diagram for explaining a case in which the short-circuit current and test voltage capacity are increased by connecting the test circuit 50 in series and parallel of the present invention.

When a higher voltage is required for the short-circuit test, two or more test circuits 50 may be connected in series and used. In addition, by connecting two or more circuits connected in series with the test circuit 50 in parallel, it is possible to meet the short-circuit current and test voltage capacity required by the test product 800.

In this configuration, the energy storage device 300 can be changed according to conditions to various capacitors (electrolytic capacitors, film capacitors, supercapacitors, etc.) having energy storage performance.

The magnitude of the test voltage and short-circuit current to be applied to the EUT 800 varies according to the rating of the EUT 800, and the test circuit 50 is combined in series or parallel in response to the EUT 800 as described above. By configuring it with an appropriate number, it has the flexibility to meet the short-circuit current and test voltage capacity required by the test product 800. According to the voltage, current, and capacity of the energy storage device 300 of the test circuit 50, the number that can be configured in series or in parallel can be determined.

By providing the charger 200, the energy storage device 300, the high-speed semiconductor switch 400, and the current control resistor 700 as described above, in a DC power source such as an environment in which the voltage supplied from the power source is used without a ripple voltage. Equipped with test equipment for DC equipment, it can be applied to short circuit test of DC equipment. In addition, it is possible to minimize the consumption of electrical energy required for the test, and the test can be repeatedly performed in a short time in a clean environment without generator noise generated when a short-circuit generator is used. In the above invention, a semiconductor switch 400 such as an IGBT may be replaced with a thyristor semiconductor switch including an integrated gate-commutated thyristor (IGCT) or a gate turn-on thyristor (GTO) to achieve the above object. have.

The power cable/power supply line from the freewheeling diode 500 and the power semiconductor switch 400 to the current control resistor 700, that is, the test line 600 is a copper busbar or coaxial to minimize the line impedance. Use a coaxial cable.

6 shows a switch 80 for a series-parallel configuration of the test circuit 50 of the present invention. The switch 80 includes four switches, and switches having a function of blocking fault current/overcurrent in the form of an MCCB (Molded Case Circuit Breaker) may be configured. The switch of Fig. 6 (a) can be used for parallel connection of two test circuits 50 as shown in Fig. 7, and the switch of Fig. 6 (b) is a series of two test circuits 50 as shown in Fig. It can be used to configure connections, etc.

In a parallel circuit configuration as the four-circuit switch 80 of the test circuit 50, the short-circuit current can be increased by using two test circuits 50 connected in parallel as shown in FIG. 7. That is, when a plurality of test circuits are connected in parallel between the charger 200 and the test product 800 in response to the required current of the test product 800, the test product is With (800), it is possible to output a high short-circuit current that meets the required current.

In addition, when the voltage of the energy storage device 300 is used in series to increase the supply voltage, the busbar 85 is connected to the outside of the terminal of the switch 80 and the two test circuits 50 are connected in series as shown in FIG. It is also possible to connect the circuit to have the effect of increasing the used voltage by sharing the voltage between the contacts by connecting with. That is, in response to the required voltage of the test product 800, when a plurality of test circuits 50 are connected in series between the charger 200 and the test product 800, the test circuits 50 connected in series are collected and tested. It is possible to output a short-circuit current with a high voltage suitable for a corresponding required voltage to the product under test 800 through the anode end of the output side of the circuit.

Short circuit test facility for DC equipment is a storage device 300 to secure DC power with high energy, which converts the capacitor and AC power into DC and charges the capacitor 200 and can instantly supply and stop a large short-circuit current. Including a thyristor or an IGBT (Insulated gate bipolar transistor) switch, which is a semiconductor switch 400 for power, and a low resistance busbar for transmitting a large current to the test item 800 or Includes a structure for testing by mounting a coaxial cable and an equipment under test to minimize line impedance. In addition, it is possible to increase the capacitance value and the voltage and current capacity by using a capacitor in a series or parallel structure, if necessary.

In particular, by adjusting the charging voltage of the charger 200, the energy required for the test is adjusted by adjusting the charging voltage of the power device using a capacitor (super capacitor, electrolytic capacitor, film capacitor for energy storage, etc.) as the energy storage device 300. (1/2 CVxV, C: capacitance, V: voltage) and the test voltage of the EUT 800 were controlled. At this time, in order to secure the voltage rating and capacitance (nxC/m, C: capacitance per unit, n: number of parallels, m: number of series) suitable for the required charging voltage, the capacitor can be configured as a series or parallel stack circuit. In addition, in order to minimize the influence of the line impedance 500, it is preferable to position the switch 400 close to the capacitor.

As described above, according to the short-circuit test facility for DC devices according to the present invention, short-circuit current tests of medium and low voltage DC devices using little power without using a large-capacity short-circuit generator for short-circuit testing of electrical devices used in DC circuits. You will be able to do it. Accordingly, it is possible to easily and at low cost to construct a DC short-circuit facility, and to minimize the use of power required in a short-circuit test. In addition, since a capacitor is used as an energy storage device, there is an effect that the test voltage can be adjusted very flexibly according to the rated voltage of the test product 800 in some cases. In addition, the magnitude of the short-circuit test current can be adjusted by adjusting the number of circuits between the energy storage device and the EUT 800 as the test current, and in the case of a fuse used to protect the battery circuit of an electric vehicle, various voltage ratings (DC300V) ~ DC1,000V or more) can be easily responded to, so there is an effect of reducing cost by reducing the configuration of equipment and charging time and test time according to product development

As described above, in the present invention, specific matters such as specific components, etc., and limited embodiments and drawings have been described, but this is provided only to help a more general understanding of the present invention, and the present invention is not limited to the above embodiments. , Anyone with ordinary knowledge in the field to which the present invention pertains will be able to make various modifications and variations without departing from the essential characteristics of the present invention. Therefore, the spirit of the present invention is limited to the described embodiments and should not be determined, and not only the claims to be described later, but also all technical ideas that are equivalent or equivalent to the claims are included in the scope of the present invention. Should be interpreted as.

10: Short circuit test voltage waveform using a short circuit generator
20: Short circuit test current waveform using a short circuit generator
30: Current waveform of the charger
40: charging voltage waveform of the energy storage device
50: single short-circuit test circuit
60: Parallel circuit configuration for expansion of short circuit current capacity of short circuit test facility
70: Series circuit configuration for expansion of short-circuit voltage capacity of short-circuit test facility
80: 4-circuit switch
85: switch terminal circuit short-circuit busbar
100: AC input of charger for short circuit test facility
200: short circuit test facility charger
210: Short circuit test facility charger positive output terminal
220: short circuit test facility charger negative output terminal
250: charger reverse current protection diode
300: short circuit test facility energy storage device
310: Discharge (dump) resistance of the energy storage device of the short circuit test facility
320: Discharge (dump) switch of the energy storage device of the short circuit test facility
330: internal equivalent series resistance (esr) of the energy storage device of the short circuit test facility
400: power semiconductor switch
500: Freewheeling Diode
550: line impedance
600: power cable or busbar
700: resistance for short-circuit current control
800: product under test

Claims (12)

A charger that receives AC power and outputs a preset voltage; And a test circuit in which both ends of the input side are connected between the other end of the forward diode connected to the anode of the charger and the cathode of the charger,
The test circuit,
An energy storage device connected to both ends of the input side and charging with the preset voltage from the charger; A semiconductor switch for outputting a short-circuit current from an output of the energy storage device to an object under test through an output-side anode; And a freewheeling diode connected in a reverse direction between the positive end of the output side and the negative end of the charger.
Short circuit test equipment comprising a. The method of claim 1,
Dump resistor and switch connected in parallel with the energy storage device
Short circuit test equipment further comprising a. The method of claim 1,
A resistor for adjusting short-circuit current connected to the positive end and connected in series to the EUT
Short circuit test facility further comprising a. The method of claim 3,
The short-circuit current adjustment resistor is a short-circuit test facility for controlling a current such that the short-circuit current output to the test object through the semiconductor switch does not exceed the rating of the semiconductor switch. The method of claim 1,
The semiconductor switch, IGBT (Insulated Gate Bipolar Transistor), or IGCT (integrated gate-commutated thyristor) or GTO (Gate Turn-on Thyristor) including a thyristor short circuit test equipment. The method of claim 1,
The product under test is a short-circuit test facility including a breaker or fuse of a DC device. The method of claim 6,
A short circuit test facility in which the control device turns off the semiconductor switch when the breaker is blocked or the fuse cannot be blown at a predetermined time. The method of claim 1,
The charger is a short-circuit test facility for charging a capacitor or a capacitor stack of the energy storage device in a constant power type, a constant current type, or a phase control rectification method. The method of claim 1,
The capacitor or capacitor stack of the energy storage device is a short circuit test facility including a super capacitor, an electrolytic capacitor, or an energy storage film capacitor. The method of claim 1,
Including a plurality of the test circuit,
A short-circuit test facility for outputting a short-circuit current with a corresponding voltage to the test product through an output side positive end by connecting a plurality of test circuits in series and parallel between the charger and the test product to correspond to the required voltage of the test product. The method of claim 1,
The test circuit includes a plurality of,
A short-circuit test facility for outputting a corresponding short-circuit current to the EUT through an output side anode of the parallel-connected test circuits by connecting a plurality of test circuits in parallel between the charger and the EUT so as to correspond to the required current of the EUT. The method of claim 1,
Short circuit test facility in which a plurality of test circuits are configured in series or in parallel using a MCCB (Molded Case Circuit Breaker) type switch to correspond to the required voltage or current of the EUT.

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