KR20080093177A - Restoration-electric power storage system of electric railway using electric double layer capacitor - Google Patents

Abstract

A restoration electric power storage system of an electric railway using an electric double layer capacitor is provided to supply electric power faster than an existing flywheel type storage device without any property conversion of the electric power by storing electrical energy by coping with an instantaneous restoration voltage quickly. A restoration electric power storage system of an electric railway using an electric double layer capacitor includes a wire(1), a filter(20), a storage(50), a DC/DC converter(30), a DC/DC filter(40), a voltage meter, and a controller(60). The filter is electrically connected to the wire and removes RF from electric power transmitted in the wire. The storage consists of the electric double layer capacitor and stores the electric power. The DC/DC converter is electrically connected to the filter and the storage, and controls opening of first and second transistors based on control signals. The DC/DC filter is electrically connected to the DC/DC converter and the storage, and removes RF noise. The voltage meter is electrically connected to the filter and detects a voltage of the wire. The controller outputs the control signal based on the voltage of the wire.

Description

{Restoration-electric power storage system of electric railway using electric double layer capacitor}

1 is a block diagram showing a regenerative power storage system according to the present invention.

<Description of the symbols for the main parts of the drawings>

10: charging part 20: filter part

30: bidirectional DC / DC converter 50: storage

60: control unit 70: current detection unit

80: voltage detection unit 90: capacitor monitoring unit

The present invention relates to a storage system for storing regenerative power using a DC / DC converter. More specifically, the present invention relates to a storage system that stores regenerative power generated by regenerative braking of an electric vehicle and returned to the line. The present invention relates to a regenerative power storage system of an urban railway using an electric double layer capacitor supplied to an electric vehicle.

Recently, as a braking method of an electric vehicle, a regenerative braking method, that is, a method of recovering kinetic energy of an electric vehicle to electric energy again when an accelerated electric vehicle decelerates for stopping to save energy, has been adopted. The regenerative braking method not only reduces the power consumption of the entire system, but also has the advantage of preventing noise problems caused by mechanical braking and wear of the brake shoes.

However, when the accelerated electric vehicle decelerates using the regenerative braking method to stop the vehicle while driving, the motor operates as a generator and performs power generation braking, thereby generating a large voltage (regenerative power) instantaneously. This regenerative power not only destabilizes the system by changing the line contact voltage by applying a large voltage to the line, but also acts as a change factor of the line voltage when the trailing train fails to accept the voltage, causing the following vehicle failure. It can also be.

On the other hand, the voltage supply method of the electric vehicle is a method of supplying after converting the AC voltage to DC voltage through the rectifier, the rectifier is connected to the circuit by the forward diode method, so the regenerative power of the electric vehicle is not returned to the power supply side. Therefore, surplus regenerative power that is not consumed on the line is converted to thermal energy and consumed, or is cut off due to overvoltage of the train entering by raising the line voltage, or the regenerative power is consumed by the magnetoresistance because the line cannot accept the voltage. Sometimes a condition occurs.

In order to solve this problem, a regenerative inverter (inverter) was installed in the DC rectifier to convert the line voltage to AC and return it to the power supply, or a separate storage device for receiving and storing regenerative power from the line was installed.

However, when regenerative power generated by several electric vehicles is returned to the power supply side without being filtered through the inverter, the regenerative power includes harmonics, which may cause unexpected damage to the consumer.

In addition, an example of using a separate storage device is a fly-wheel storage device of the Republic of Korea Patent Application No. 10-0659366-0000 filed December 24, 2004.

The flywheel storage device is an electric supply path and at the same time a path for returning electricity generated by regenerative braking when the electric vehicle is decelerated; A gate electrically connected to the wire and capable of intermittent power input / output; An energy storage device connected to the gate and configured to convert and store the supplied electrical energy into kinetic energy and convert the stored kinetic energy into electrical energy by outputting the control signal; A voltage detector electrically connected to the wire to detect the wire voltage; A gate driving circuit driving the gate by a control signal according to the information detected by the voltage detector; And a microprocessor configured to determine a detected voltage of the voltage detector, output a control signal to a gate driving circuit, control an operation of an energy storage device, and control conversion between electric energy and kinetic energy and power input / output.

However, since the storage unit is mechanically configured and operated, the noise is high, the volume of the device itself is large, and the process of converting electrical energy into kinetic energy includes an inefficient aspect of receiving and storing instantaneous electrical energy. There was room.

As to solve the above problems,

An object of the present invention is to provide a means for converting the regenerative power into a DC voltage of an appropriate size to store the electrical energy itself and to provide the electrical energy again if necessary.

In addition, an object of the present invention is to provide a semi-permanent storage means that can respond quickly to the instantaneous regenerative voltage, can be quickly charged and discharged, compared to the conventional flywheel type storage device.

In order to achieve the above technical problem, the present invention includes a wire, a filter unit, a storage unit, a bidirectional DC / DC converter, a DC / DC filter, a voltage detector, and a controller.

The wire is a path for supplying electricity to the electric vehicle, and the electricity generated by the regenerative braking when the electric vehicle is decelerated is returned. The filter unit is electrically connected to the wire to remove high frequency components. The storage section consists of an electrical double layer capacitor that stores electrical energy. The bidirectional DC / DC converter is electrically connected between the filter unit and the storage unit to open and close the first transistor and the second transistor according to a control signal. The DC / DC filter is electrically connected between the bidirectional DC / DC converter and the storage to remove high frequency noise. The voltage detector is electrically connected to the filter unit to detect the voltage of the wire. The controller determines the voltage of the wire detected by the voltage detector and outputs an open / close control signal to each of the first transistor and the second transistor of the bidirectional DC / DC converter.

Furthermore, the present invention may further include a charging unit.

The charging unit is electrically connected between the wire and the filter unit to prevent overcurrent during charging of the capacitor of the filter unit.

Furthermore, the present invention may further include a current detector.

The current detector detects the amount of current flowing into the filter unit and outputs it to the controller. In this case, the charging circuit further includes a cutoff switch for opening and closing an electrical connection between the charging circuit and the wire, and the controller opens the cutoff switch when an overcurrent is detected from the current detector.

On the other hand, the present invention may further include a capacitor monitoring unit.

The capacitor monitoring unit measures the voltage and power of the storage unit and outputs it to the control unit. In this case, the controller outputs a signal for controlling the first transistor to an off state when the storage unit is fully charged in a charging mode, and when the voltage input from the capacitor monitoring unit is less than or equal to a reference voltage in a power supply mode. Outputs a signal that controls the transistor in the off state.

Hereinafter, exemplary embodiments of the present invention will be described with reference to FIG. 1. 1 is a circuit diagram schematically showing a preferred embodiment of the present invention.

Hereinafter, an electric dual layer capacitor (EDLC) is abbreviated as EDLC.

According to a preferred embodiment of the present invention, the charging unit 10, the filter unit 20, the bidirectional DC / DC converter 30, the DC / DC filter 40, the storage unit 50, the control unit 60, The current detection unit 70 and the voltage detection unit 80 are provided.

The filter unit 20 will be described.

Since DC-DC converter basically oscillates at high frequency (several kHZ ~ hundreds of kHZ), it boosts and decreases, so that high-frequency noise generated by transistors or FETs from inside passes through the input and output power lines. A filter is needed to prevent it.

In the present embodiment, the filter unit 20 is composed of a capacitor 22 connected in parallel with the inductor 21 connected in series, but the filter unit 20 is for removing high frequency noise and may be replaced with another equivalent circuit. .

The charging unit 10 will be described.

The filter unit 20 serves to block the passage of high frequency noise. The filter unit 20 according to the present exemplary embodiment includes a capacitor. Small capacitors are not a big problem because the time to charge is short. However, a large capacitor has a risk of overcurrent because the capacitor is short-circuited until the charge progresses to a certain degree and the current amount decreases. Such overcurrent can cause a big problem in the peripheral system, so a protection circuit should be provided. The charging unit 10 plays a role of such a protection circuit.

When the charging switch 13 is turned off, the overcurrent is prevented from flowing by the resistor 15 of the charging unit 10. After the capacitor 22 is sufficiently charged, the charging switch 13 is turned on.

Impedance 11 of the charging section is for impedance matching of the circuit and can be selected as necessary. Disconnect switch 12 is to cut off the power in the system separately from the high-speed circuit breaker (5).

The bidirectional DC / DC converter 30 will be described.

The bidirectional DC / DC converter 30 converts the DC voltage into a specific DC voltage in both directions while switching the first transistor 31 and the second transistor 32 by pulse width modulation (PWM) control. When the second transistor is turned off by the control signal and the first transistor 31 is switched to the on state, the second transistor is operated as a buck converter. On the other hand, when the first transistor is off and the second transistor 32 is switched to the on state, it operates as a boost converter. It is preferable. In this case, the main switching role is the second transistor.

The DC / DC filter 40 will be described.

As described in the filter unit 20, the DC / DC filter 40 will be described in order to prevent high frequency noise from flowing into surrounding devices and causing various problems. In the present embodiment, the inductor 41 is used, but it can be replaced by several circuits having the same function.

The storage unit 50 will be described.

The storage unit 50 is configured by connecting several EDLCs 53 in parallel to store the regenerative power received through the bidirectional DC / DC converter 30. At this time, the storage time is determined by the capacity of the capacitor.

On the other hand, the switch 51 and the resistor 52 are portions for artificially consuming the power stored in the capacitor.

Various detection devices are described.

The current detector 70 measures the current flowing into the filter unit 20 and outputs it to the controller 60 to be described later, and the voltage detector 80 is a voltage across the capacitor 22 of the filter unit 20, that is, the wire The voltage of (1) is detected and output to the controller 60. The capacitor monitoring unit 90 measures the voltage and the amount of charge of the EDLC 53 of the storage unit 50 and outputs the same to the control unit 60.

The control unit 60 will be described.

The control unit 60 can be configured as a microprocessor or a general computer system.

In domestic urban railways, subways and light rail trains, the reference voltage provided to a vehicle is most often 1500V or 750V. The reference voltage for storing regenerative power is set to be larger than the applied voltage, and the reference voltage for supplying regenerative power to the wire again is set to be smaller than the applied voltage. For example, when the applied voltage 1500V, the regenerative power storage reference voltage is set to 1800V greater than the applied voltage, and the regenerative power supply reference voltage is set to 1000V smaller than the applied voltage, the configuration of the controller 60 is as follows.

The control unit 60 receives a control line voltage from the voltage detector 80 and supplies a control signal for switching the first transistor 31 to an on state in order to switch to a charging mode when the line 1 voltage becomes 1800 V or more. Output The bidirectional DC / DC converter then acts as a Buck Converter.

In addition, when the line voltage falls below 1000 V, the controller outputs a signal for controlling the first transistor to the off state and the second transistor to the on state. The bidirectional DC / DC converter then acts as a boost converter.

In the present embodiment, the control unit outputs a control signal to the first transistor 31 and the second transistor 32 by pulse width modulation (PWM). Since PWM control is a well-known method, detailed description is abbreviate | omitted.

On the other hand, when the capacitor monitoring unit 90 outputs that the storage unit 50 is in a buffered state, the storage voltage measured by the capacitor monitoring unit 90 is not switched to the charging mode even when the wire voltage becomes 1800V (storage reference voltage) or more. When the voltage of the unit 50 is 1000 V (supply reference voltage) or less, the power supply mode is not switched.

Hereinafter, the operation by the present embodiment will be described.

Urban trains run repeatedly between stops and stops. At this time, the electric vehicle is accelerated by driving the motor (motor) by receiving DC voltage through the wire, and after being accelerated at a constant speed, it performs inertia operation using inertia. Regenerative power is generated by generating power using the inertia kinetic energy of electric cars. This regenerative power is returned to the wire.

In order to store such regenerative power, the operation or operation of the regenerative power storage system according to the present embodiment may be classified into an operation initial mode, a general monitoring mode, a charging mode, and a power supply mode.

Referring to FIG. 1, the operation initial mode is a step for charging the capacitor 22 of the filter circuit.

As described above, the charging unit 10 prevents overcurrent by the charging switch 13 and charges the capacitor 22 of the filter unit 20. At this time, the charging switch is switched to the on state when the capacitor 22 of the filter unit 20 is about 70% charged. When charging is completed, a voltage equal to the line voltage is applied to both ends of the capacitor of the filter unit 20.

In the general monitoring mode, the voltage of the wire 1 is measured and compared with a reference value without the charge / discharge operation of the EDLC 53.

When the voltage detector 80 measures the line 1 voltage and outputs the measured value to the controller 60, the controller determines whether to switch to the charging mode or the power supply mode by comparing the reference value with the reference value. Therefore, the control signal is output to the bidirectional DC / DC converter.

Specifically, in the present embodiment, when the wire voltage is 1800V or more and the storage unit 50 is not in a fully charged state, it switches to the charging mode to operate as a buck converter, and the wire voltage falls below 1000V and the EDLC of the storage unit 50 is reduced. 53) If the voltage at both ends is not below the standard value, it switches to the power supply mode and operates as a boost converter. Meanwhile, the storage and supply reference voltages are selectable according to the situation of the wires and the surrounding system.

When the charging mode is switched, the bidirectional DC / DC converter operates as a buck converter because the first transistor is switched to the on state and the second transistor is switched to the off state, so the wire voltage is rated at the EDLC 53 of the storage unit 50. The power transferred to the internal voltage and delivered from the live wire is stored in the EDLC 53.

On the other hand, when the EDLC 53 is measured as buffered by the capacitor monitoring unit 90, the control unit 60 outputs a control signal for turning off the first transistor 31, ends the charging mode, and switches to the normal monitoring mode. .

When switched to power supply mode, the bi-directional DC / DC converter acts as a boost converter, so the power stored in the EDLC is converted back to a suitable voltage for supply to the line. At this time, if the voltage of the EDLC falls below a certain level, the controller 60 outputs a control signal for turning off the first transistor and / or the second transistor to terminate the power supply mode and switch to the normal monitoring mode.

Although the preferred embodiments of the present invention have been described above, the technical spirit of the present invention is not limited to the above-described preferred embodiments, and various urban railway regenerative electric powers without departing from the technical spirit of the present invention specified in the claims. It can be implemented as a storage system.

From the structural features of the present invention described above,

The urban railway regenerative power storage system according to the present invention converts the regenerative power into DC voltage of an appropriate size and stores the electrical energy itself, and when the line goes below the reference voltage, the electric line is provided to the adjacent electric vehicle through the line again. Can be. Therefore, the quick response to the regenerative energy that occurs momentarily prevents the unstable line voltage fluctuating and other systems become unstable. Especially in the urban railway section where the fluctuation of the line voltage is relatively large due to the short operating period. Is even larger.

In addition, the metropolitan railway regenerative power storage system according to the present invention stores electrical energy at a high speed in response to instantaneous regenerative voltage as compared to a conventional flywheel type storage device, and also supplies energy itself through supplying wires and the like. By supplying without changing the properties of the power can be supplied quickly.

In addition, by using a capacitor as a storage device, weight and volume can be reduced as compared to a storage device using a chemical battery or a mechanical property, and it is possible to install in various capacities.

That is, the present invention has the effect of increasing the energy efficiency and stability of the entire urban railway system.

Claims (4)

A route for supplying electricity to the electric vehicle, wherein the electricity generated by the regenerative braking when the electric vehicle is decelerated is returned; A filter unit electrically connected to the wire to remove high frequency components; A storage unit comprising an electric double layer capacitor for storing electrical energy; A bidirectional DC / DC converter electrically connected between the filter unit and the storage unit and controlled by opening and closing the first transistor and the second transistor according to a control signal; A DC / DC filter electrically connected between the bidirectional DC / DC converter and the storage unit to remove high frequency noise; A voltage detector electrically connected to the filter unit to detect a voltage of the wire; And a control unit for determining the voltage of the wire detected by the voltage detector and outputting an open / close control signal to each of the first transistor and the second transistor of the bidirectional DC / DC converter. The method of claim 1, And a charging unit electrically connected between the wire and the filter unit to prevent overcurrent during charging of the capacitor of the filter unit. The method of claim 2, Further comprising a current detecting unit for detecting the amount of current flowing into the filter unit and outputs it to the control unit, The charging circuit further includes a blocking switch for opening and closing the electrical connection of the charging circuit and the wire, The control unit for regenerative power storage system of the urban railway to open the cutoff switch when the over current is detected from the current detector. The method of claim 1, And a capacitor monitoring unit 90 measuring voltage and power of the storage unit and outputting the measured voltage to the control unit. The controller outputs a signal for controlling the first transistor to an off state when the storage unit is fully charged in a charging mode, and when the voltage input from the capacitor monitoring unit is less than a reference voltage in a power supply mode, the second transistor. Urban regenerative power storage system, characterized in that for outputting a signal for controlling the off state.

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