Time constant suppression device of direct-current short-circuit power supply

Abstract

The utility model belongs to the technical field of low-voltage electric appliance detection, and particularly discloses a time constant suppression device of a direct-current short-circuit power supply, which comprises the direct-current short-circuit power supply, a compensation circuit and a test output circuit are electrically connected between the output end of the direct-current short-circuit power supply and a GND (ground), and the compensation circuit is connected with the test output circuit in parallel; the compensation circuit comprises a compensation circuit inductor, a compensation circuit resistor and a compensation capacitor which are connected in series; and the test output circuit comprises a line control switch and a test product access terminal which are connected in series. On the basis of the direct-current short-circuit power supply, the compensation circuit is connected in parallel, so that the time constant of the traditional direct-current short-circuit power supply can be suppressed, the inductance of the direct-current short-circuit power supply is equivalently reduced, the rise rate of the current in the initial stage is improved, and short-circuit current with smaller time constant is provided for the tested vehicle-mounted relay and fuse; and the short-circuit working condition test of the relay and the fuse for the electric vehicle is satisfied.

Description

Technical Field

[0001] The utility model relates to the technical field of low-voltage electrical appliance detection, in particular to a time constant suppression device for a DC short-circuit power supply, which is applied to a short-circuit test system of a DC relay and a fuse for an electric vehicle. Background Art

[0002] Onboard relays and fuses are crucial electrical components in electric vehicles. They control high currents with low currents, reduce the number of manual switches, protect switches and wires, and, together with other electrical components, form control circuits, enhancing the intelligence of electric vehicles. Currently, the main functions of relays and fuses used in electric vehicles are as follows: controlling the on-off of high currents; reducing the number of manual switches; sequentially controlling electrical appliances; protecting wires and conductors; and quickly interrupting high currents in short circuits.

[0003] However, the traditional DC short-circuit test system has the following defects: large line inductance, large time constant, and low current rise rate in the initial stage, which is inconsistent with vehicle operating conditions, resulting in low control accuracy of the test system. Utility Model Content

[0004] The purpose of the utility model is to solve the technical problems existing in the background technology, and to this end, a time constant suppression device for a DC short-circuit power supply is provided.

[0005] In order to achieve the above purpose, the technical solutions adopted by this utility model are as follows:

[0006] A time constant suppression device for a DC short-circuit power supply, comprising a DC short-circuit power supply, wherein a compensation circuit and a test output circuit are electrically connected between an output terminal of the DC short-circuit power supply and GND, and the compensation circuit and the test output circuit are connected in parallel;

[0007] The compensation circuit includes a compensation line inductance, a compensation line resistance and a compensation capacitor connected in series;

[0008] The test output circuit includes a line control switch and a test product access terminal connected in series.

[0009] The following is a technical solution further defined by the present invention: the DC short-circuit power supply includes a three-phase power supply, a transformer and a rectifier, the three-phase power supply is electrically connected to the input end of the transformer, the output end of the transformer is electrically connected to the input end of the rectifier, the output end of the rectifier is electrically connected to one end of the DC line inductor, the other end of the DC line inductor is electrically connected to one end of the DC line resistor, and the other end of the DC line resistor is electrically connected to the compensation circuit and the test output circuit.

[0010] The following is a technical solution further defined by the present invention: the DC line inductance and the DC line resistance are both arranged on the DC line, and a current measurement point is arranged on the DC line.

[0011] The following is a technical solution further defined by the present invention: the compensation line inductance, compensation line resistance and compensation capacitor are all arranged on the compensation line, and a current measurement point is provided on the compensation line.

[0012] The following is a technical solution further defined by the present invention: the line control switch and the test product access terminal are both provided on the test output line, and a current measurement point is provided on the test output line.

[0013] Compared with the prior art, the present invention has the following technical effects:

[0014] The utility model is based on a DC short-circuit power supply and connects a parallel compensation circuit. It can suppress the time constant of the traditional DC short-circuit power supply, equivalently reduce the inductance of the DC short-circuit power supply, and improve the rising rate of the current in the initial stage. It provides a short-circuit current with a smaller time constant for the tested on-board relays and fuses, and meets the short-circuit working condition test of relays and fuses for electric vehicles.

[0015] The present invention will be further described below with reference to the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0017] Figure 1 This is a circuit connection diagram of the utility model;

[0018] Figure 2 It is a simulation circuit connection diagram of the utility model;

[0019] Figure 3 It is a simulation waveform diagram of the utility model;

[0020] Figure 4 It is the measured waveform diagram of the present utility model. DETAILED DESCRIPTION

[0021] To make the above-mentioned objects, features, and advantages of the present invention more clearly understood, the following detailed description of specific embodiments of the present invention is provided in conjunction with the accompanying drawings. The following description sets forth many specific details to facilitate a full understanding of the present invention. However, the present invention can be implemented in many other ways than those described herein, and those skilled in the art may make similar modifications without departing from the scope of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0022] like Figure 1 As shown, a time constant suppression device for a DC short-circuit power supply is provided, comprising a DC short-circuit power supply, a compensation circuit, a test output circuit and other parts.

[0023] The DC short-circuit power supply includes a three-phase power supply, a transformer, a rectifier, a DC line inductor L1, a DC line resistor R1, and a current measurement point T1 on the DC line.

[0024] The compensation circuit includes a compensation line inductance L, a compensation line resistance R, a compensation capacitor C connected in series, and a current measurement point T2 on the compensation line.

[0025] The test output circuit includes a line control switch K1, a test product access terminal and a current measurement point T3 on the test output line connected in series. The test product access terminal is connected to the test sample SP.

[0026] Before the test begins, the line control switch K1 is in the disconnected state, and the DC short-circuit power supply pre-charges the compensation capacitor C. The charging time is not less than 20ms, and the compensation capacitor C obtains the same voltage as the DC short-circuit power supply.

[0027] After charging is complete, the circuit control switch K1 is closed, and the DC short-circuit power supply and the compensation circuit simultaneously apply current to the test sample SP. The compensation circuit's lower inductance and faster current rise rate compensate for the DC short-circuit power supply's slow current rise rate. Furthermore, the current flowing through the test sample SP consistently follows the exponential curve during its rise. When the DC short-circuit power supply current stabilizes, the energy in the compensation capacitor C is depleted, and the current flowing through the test sample SP then equals the DC short-circuit power supply current.

[0028] Based on the time constant suppression device of a DC short-circuit power supply provided in this embodiment, a simulation model is established in Simulink, such as Figure 2 As shown:

[0029] The simulation calculation satisfies the relationship between the current time constant after compensation and the capacitance and resistance of the compensation loop when the voltage, current and time constant of a certain DC short-circuit system are constant and the inductance of the compensation loop is the inherent inductance of the line.

[0030] The model includes an AC power supply, a rectifier transformer, a rectifier bridge, a DC short-circuit system impedance Z1, a compensation capacitor C, an adjustable impedance Z2, and an IGBT control switch. Before the IGBT switches on, the DC short-circuit power supply charges the compensation capacitor C to a voltage equal to the DC short-circuit power supply voltage. By adjusting the compensation capacitor value and the impedances Z1 and Z2, the current value and time constant in the circuit are adjusted, and the IGBT controls the on-time of the current. An oscilloscope displays the voltage and current waveforms and data.

[0031] The simulation parameters are set as follows: voltage 426V, current 15.25kA, time constant 1.18ms, compensation circuit parameters: resistance 41mΩ, line inherent resistance 12.78mΩ, need to input resistance 28.2mΩ; inductance 8.5uH, line inherent resistance 7.97uH, considering the input resistance inductance value is 0.5uH; capacitance 33mF. The simulation waveform is as follows: Figure 3 As shown, the red color is the DC short-circuit power supply current T1, with a current value of 15.25kA and a time constant of 1.2ms; the blue color is the compensation current T2; and the green color is the compensated output current T3, with a time constant of 0.24ms.

[0032] The measured parameters are as follows: DC voltage 426V, compensation line inherent resistance 12.78mΩ, input resistance 28mΩ; inductance 8.5uH, line inherent resistance 7.97uH, considering the inductance value of the input resistance is 0.5uH; capacitance 33mF. The measured waveform is as follows: Figure 4 As shown, the red color is the DC short-circuit power supply current T1, with a current value of 15.5kA and a time constant of 1.2ms; the green color is the compensation current T2; and the yellow color is the compensated output current T3, with a time constant of 0.25ms.

[0033] The above description is merely a preferred embodiment of the present invention and does not constitute any form of limitation to the present invention. Any person skilled in the art can, without departing from the scope of the present invention, utilize the methods and technical content disclosed above to make many possible variations and modifications to the present invention, or modify it into equivalent embodiments with equivalent variations. Therefore, any equivalent variations based on the shape, structure, and principle of the present invention that do not depart from the content of the present invention are intended to be covered by the scope of protection of the present invention.

Claims

1. A time constant suppression device for a DC short-circuit power supply, characterized in that: A DC short-circuit power supply is included, wherein a compensation circuit and a test output circuit are electrically connected between an output end of the DC short-circuit power supply and GND, and the compensation circuit and the test output circuit are connected in parallel; The compensation circuit includes a compensation line inductance, a compensation line resistance and a compensation capacitor connected in series; The test output circuit includes a line control switch and a test product access terminal connected in series.

2. A time constant suppression device for a DC short-circuit power supply according to claim 1, characterized in that: The DC short-circuit power supply includes a three-phase power supply, a transformer and a rectifier. The three-phase power supply is electrically connected to the input end of the transformer, the output end of the transformer is electrically connected to the input end of the rectifier, the output end of the rectifier is electrically connected to one end of the DC line inductor, the other end of the DC line inductor is electrically connected to one end of the DC line resistor, and the other end of the DC line resistor is electrically connected to the compensation circuit and the test output circuit.

3. A time constant suppression device for a DC short-circuit power supply according to claim 2, characterized in that: The DC line inductance and the DC line resistance are both arranged on the DC line, and a current measurement point is arranged on the DC line.

4. The time constant suppression device for a DC short-circuit power supply according to claim 1, wherein: The compensation line inductance, compensation line resistance and compensation capacitor are all arranged on the compensation line, and a current measurement point is arranged on the compensation line.

5. The time constant suppression device for a DC short-circuit power supply according to claim 1, wherein: The line control switch and the test product access terminal are both arranged on the test output line, and a current measurement point is arranged on the test output line.

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