JP2022047389A - Auxiliary power unit - Google Patents

Abstract

To make an auxiliary power unit smaller and lighter.SOLUTION: An auxiliary power unit 1 includes a converter 13 that converts AC power to DC power, a filter capacitor 15 that smooths the DC power, an inverter 16 that converts the DC power smoothed by the filter capacitor 15 into single-phase AC power, a leakage transformer 17 that directly inputs an output voltage of the inverter 16 to the primary side, and a dry capacitor 18 placed on the secondary side of the leakage transformer 17.SELECTED DRAWING: Figure 1

Description

The present invention relates to an auxiliary power supply device.

Conventionally, there is known an auxiliary power supply device that converts electric power input from an AC overhead wire by a converter and an inverter and supplies a three-phase voltage via a filter reactor and a filter capacitor (see, for example, Patent Document 1). Further, an auxiliary power supply device that employs a leakage transformer as an isolation transformer is known (see, for example, Patent Document 2).

Japanese Unexamined Patent Publication No. 2006-20394 Japanese Unexamined Patent Publication No. 8-317692

However, the conventional auxiliary power supply device that converts AC power to perform single-phase AC output has a problem that the device becomes large.

An object of the present invention made in view of such circumstances is to provide an auxiliary power supply device capable of being compact and lightweight.

In order to solve the above problems, the auxiliary power supply device according to the present invention simply converts AC power into DC power, a filter capacitor that smoothes the DC power, and DC power smoothed by the filter capacitor. It includes an inverter that converts to phase AC power, a leakage transformer that directly inputs the output voltage of the inverter to the primary side, and a dry capacitor arranged on the secondary side of the leakage transformer.

Further, in the auxiliary power supply device according to the present invention, the inverter may have a SiC element as a switching element.

Further, in the auxiliary power supply device according to the present invention, the converter may perform step-up control and the inverter may perform step-down control.

Further, in the auxiliary power supply device according to the present invention, the filter capacitor may be a film capacitor.

According to the present invention, the auxiliary power supply device can be made smaller and lighter.

It is a block diagram which shows the structural example of the auxiliary power supply device which concerns on one Embodiment. It is a block diagram which shows the configuration example of the conventional auxiliary power supply device.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

First, a conventional auxiliary power supply device will be described for comparison with the auxiliary power supply device according to the present invention. FIG. 2 is a block diagram showing a configuration example of a conventional auxiliary power supply device. In the example shown in FIG. 2, the conventional auxiliary power supply device 2 includes a filter reactor 12, a converter 13', a charging circuit 21, a discharging circuit 14, a filter capacitor 15', an inverter 16', and an output side filter reactor. 22, an oil condenser 23, and an insulating transformer 24 are provided.

The filter reactor 12 suppresses harmonic noise of the AC voltage (for example, 400V) input to the auxiliary power supply device 2 and outputs it to the converter 13'.

The converter 13'diode rectifies the AC power input to the auxiliary power supply device 2 and converts it into DC power.

The charging circuit 21 is a circuit in which a thyristor 211 and a charging resistor 212 are connected in parallel. When the filter capacitor 15'is charged, the charging circuit 21 turns off the thyristor 211 and charges the filter through the charging resistor 212, so that the inrush current can be suppressed.

The discharge circuit 14 is a circuit in which a switch 141 and a discharge resistor 142 are connected in series. By turning on the switch 141, the discharge circuit 14 discharges the electric charge accumulated in the filter capacitor 15'via the discharge resistor 142.

The filter capacitor 15'is connected in parallel to the input side of the inverter 16', smoothes the DC voltage input to the inverter 16', and keeps it constant.

The inverter 16'has a plurality of switching elements (for example, IGBTs), converts the DC power smoothed by the filter capacitor 15'to single-phase AC power by the PWM method, and outputs the DC power to the isolation transformer 24. The switching frequency of the inverter 16'is, for example, 2.25 kHz.

The output side filter reactor 22 and the oil capacitor 23 form an LC filter circuit, suppress harmonic noise of the AC voltage input from the inverter 16', and output to the isolation transformer 24.

The isolation transformer 24 transforms the AC voltage input from the inverter 16'at a predetermined transformation ratio. For example, the isolation transformer 24 outputs an AC voltage of 100 V50 Hz.

FIG. 1 is a block diagram showing a configuration example of an auxiliary power supply device according to an embodiment of the present invention. In the example shown in FIG. 1, the auxiliary power supply device 1 includes a charging circuit 11, a filter reactor 12, a converter 13, a discharging circuit 14, a filter capacitor 15, an inverter 16, a leakage transformer 17, and a dry capacitor 18. , Equipped with.

The auxiliary power supply device 1 is mounted on a Shinkansen, for example, and converts AC power collected from an overhead line into stable single-phase AC power. Then, the auxiliary power supply device 1 supplies single-phase AC power to, for example, an auxiliary device in a Shinkansen train.

The charging circuit 11 is a circuit in which the contactor 111 and the charging resistance 112 are connected in parallel. When the filter capacitor 15 is charged, the charging circuit 11 opens the contactor 111 and charges via the charging resistor 112, so that the inrush current can be suppressed.

The filter reactor 12 is connected in series with the charging circuit 11, suppresses harmonic noise of the AC voltage input to the auxiliary power supply device 1, and outputs the noise to the converter 13.

The converter 13 converts the AC power input to the auxiliary power supply device 1 into DC power.

The converter 13 may have a plurality of switching elements and perform boost control. For example, the converter 13 converts and boosts the 400V AC voltage input to the auxiliary power supply 1 to a 750V DC voltage. By performing boost control with the converter 13, it is possible to suppress fluctuations in the output voltage due to fluctuations in the input voltage and stabilize the DC link. Further, since the output current of the converter 13 can be reduced by boosting the voltage, the filter capacitor 15 can be made smaller and lighter. For example, the filter capacitor 15'shown in FIG. 2 is an oil capacitor, but the filter capacitor 15 can be a film capacitor.

The discharge circuit 14 is a circuit in which a switch 141 and a discharge resistor 142 are connected in series. By turning on the switch 141, the discharge circuit 14 discharges the electric charge accumulated in the filter capacitor 15 via the discharge resistor 142.

The filter capacitor 15 is connected in parallel to the input side of the inverter 16 to smooth the DC voltage input to the inverter 16 and keep it constant.

The inverter 16 has a plurality of switching elements, converts the DC power smoothed by the filter capacitor 15 into single-phase AC power by the PWM method, and outputs the DC power to the leakage transformer 17. When the converter 13 performs step-up control, the inverter 16 performs step-down control. For example, the inverter 16 converts the 750V DC voltage input from the converter 13 into an AC voltage of 300V and steps down the voltage.

Further, it is preferable that the inverter 16 has a SiC (silicon carbide) element as a switching element. As a result, the switching frequency of the inverter 16 can be made higher than before. The switching frequency of the inverter 16 in this case is, for example, 7.5 kHz. Further, by using the SiC element, the inverter 16 can be made smaller and lighter. Further, since the inverter 16 can reduce the time constant of the filter circuit by increasing the switching frequency by using the SiC element, it becomes easy to replace the conventional isolation transformer with the leakage transformer 17.

The leakage transformer 17 directly inputs the AC voltage output by the inverter 16 to the primary side, and transforms the AC voltage at a predetermined transformation ratio. Here, inputting directly to the primary side means that the filter circuit is not arranged on the primary side. Since the leakage transformer 17 has an inductor, it is not necessary to arrange the output side filter reactor 22 as shown in FIG. 2 on the primary side. Therefore, the auxiliary power supply device 1 can be made smaller and lighter. The voltage after transformation is output to the secondary side of the leakage transformer 17. For example, when the voltage input from the inverter 16 is an AC voltage of 300 V and the transformation ratio is 3: 1, an AC voltage of 100 V is output to the secondary side of the leakage transformer 17.

The dry capacitor 18 is arranged on the secondary side of the leakage transformer 17 and suppresses harmonic noise of the output voltage on the secondary side of the leakage transformer 17.

The dry condenser 18 is smaller and lighter than the oil condenser, but has a lower rated voltage than the oil condenser. As shown in FIG. 2, conventionally, an LC filter circuit having a single-phase AC output voltage has been used on the primary side of an isolation transformer 24. Since the voltage on the primary side is high, an oil capacitor 23 having a high rated voltage was used in the LC filter circuit. On the other hand, in the auxiliary power supply device 1, a leakage transformer 17 is used as an isolation transformer, and a capacitor is arranged on the secondary side, so that a dry capacitor 18 having a low rated voltage can be used. As a result, the filter circuit for the single-phase AC output voltage is made smaller and lighter, so that the auxiliary power supply device 1 can be made smaller and lighter.

Although the above embodiments have been described as typical examples, it will be apparent to those skilled in the art that many modifications and substitutions can be made within the spirit and scope of the present invention. Therefore, the invention should not be construed as limiting by the embodiments described above, and various modifications or modifications can be made without departing from the claims.

1 Auxiliary power supply 11 Charging circuit 12 Filter reactor 13 Converter 14 Discharging circuit 15 Filter capacitor 16 Inverter 17 Leakage transformer 18 Dry capacitor 111 Contactor 112 Charging resistance 141 Switch 142 Discharging resistance

Claims (4)

A converter that converts AC power to DC power,
The filter capacitor that smoothes the DC power and
An inverter that converts DC power smoothed by the filter capacitor into single-phase AC power, and
A leakage transformer that directly inputs the output voltage of the inverter to the primary side,
A dry capacitor arranged on the secondary side of the leakage transformer,
Auxiliary power supply equipped with. The inverter has a SiC element as a switching element.
The auxiliary power supply according to claim 1. The converter performs boost control and
The inverter performs step-down control.
The auxiliary power supply according to claim 1 or 2. The filter capacitor is a film capacitor.
The auxiliary power supply according to claim 3.

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