JP5353068B2 - Regenerative power absorber - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To detect open failure and short-circuit failure of a switching element constituting a chopper circuit. <P>SOLUTION: A plurality of regenerative electric power absorbing parts, each constituted by a chopper circuit and a regenerative resistance 8, are connected to a line 3 in parallel, to heat-generatively absorb the regenerative electric power regenerated in the line 3 by the regenerative resistance 8. A reactor L2 for current smoothing is provided to the output side of each chopper circuit, and a current detector 16 for detecting a chopper current is provided in each chopper circuit. An instruction value of the chopper current per chopper circuit is calculated according to a deviation of a set value of an input voltage from the line 3 and the input voltage, and a duty ratio of each chopper circuit is calculated according to a deviation of the instruction value of the chopper current and the detection value, to generate a gate signal of a switching element SW of each chopper circuit so that the gate signal has the duty ratio. Further, a short-circuit failure or open failure of the switching element SW is detected when the deviation of the instruction value of the chopper current and the detection value is large. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a regenerative power absorbing device such as a DC electric railway.

  When a DC electric vehicle such as a DC electric railway performs a regenerative braking operation, regenerative power is released to the overhead line, and the voltage of the overhead line rises. When the voltage of the overhead line rises, the regenerative braking becomes worse, and there is a risk of overvoltage failure of the DC electric vehicle and the overhead line. In order to eliminate such inconvenience, a regenerative power absorbing device that absorbs regenerative power is provided. FIG. 3 shows a configuration diagram of a conventional regenerative braking system for a DC electric railway, in which 1 is an AC power supply, and its output voltage Vs is supplied to a substation 2 composed of a transformer and a rectifier. Rectify. The DC power output from the substation 2 is supplied to the DC electric vehicle 5 through the overhead line 3 and the overhead line impedance 4. A regenerative power absorbing device 6 is connected to the overhead line 3.

  Electric power is supplied from the substation 2 to the DC electric vehicle 5 while the DC electric vehicle 5 is in power operation, and regenerative power is absorbed from the DC electric vehicle 5 to the regenerative power absorbing device 6 while the DC electric vehicle 5 is in regenerative braking. The rise in the voltage of the overhead wire 3 is suppressed. The regenerative power absorbing device 6 includes a series circuit of a chopper circuit 7 and a regenerative resistor 8, and a plurality of the series circuits are connected in parallel according to the device capacity. The regenerative power is absorbed as heat by the regenerative resistor 8. The chopper circuit 7 operates when the input voltage Vdc1 becomes equal to or higher than the set voltage, and operates so that the input voltage Vdc1 of the chopper circuit 7 becomes a set value while the DC electric vehicle 5 is generating regenerative power. . Vdc2 is the voltage of the DC electric vehicle 5.

  FIG. 4 shows a detailed circuit configuration of a conventional regenerative power absorbing device 6, which is connected to the overhead line 3 (DC power supply bus) and detects a regenerative current between DC input terminals T 1 and T 2 to which an input voltage Vdc 1 is applied. One end of a plurality of chopper units 10 is connected in parallel via the detector 9 and the reactor L1, and a common regenerative resistor 8 is connected to the other end of each chopper unit 10. Each chopper unit 10 includes a capacitor C, a switching element SW, and a free-wheeling diode D connected in parallel to the connection ends on the DC input terminals T1, T2, and the chopper is constituted by the switching element SW, the diode D, and a common reactor L1. A circuit is formed. Further, an LC filter is constituted by a series circuit of the reactor L1 and the capacitor C, and harmonics are prevented from being generated in the overhead wire voltage by the chopper operation. The number of parallel installations of the chopper units 10 is determined according to the regenerative current.

  FIG. 5 is a control block diagram of the above-described conventional regenerative power absorbing device 6, and a DC voltage (input voltage) set value Vdcref and a DC voltage (input voltage) Vdc 1 are input to the comparison unit 12 of the chopper duty ratio calculation unit 11. The deviation between the two is obtained. This deviation is input to the proportional-plus-integral calculation unit 13, where the proportional-integral calculation is performed, and the chopper duty ratio (= ON time of the switching element SW / switching cycle) is calculated. The chopper duty ratio, which is the output of the chopper duty ratio calculation unit 11, is input to the chopper gate signal generation unit 14, and the chopper gate signal generation unit 14 generates a gate signal so as to have this chopper duty ratio. The signal is input to the gate of the switching element SW of the chopper unit 10 and its duty ratio (conduction ratio) is controlled. That is, when the ON time of the switching element SW of each chopper unit 10 is changed, the average current flowing through the regenerative resistor 8 changes. Therefore, by controlling the duty ratio, the regenerative power absorption amount of the regenerative power absorption device 6 is changed, and the input voltage Vdc1 is controlled to coincide with the set value Vdcref.

In addition, there exists patent documents 1-3 as prior art document information relevant to invention of this application.
Japanese Unexamined Patent Publication No. 63-49559 JP-A 63-103745 JP 2004-168214 A

  By the way, in the above-described conventional regenerative power absorbing device, the regenerative resistor 8 is selected to a value that can consume the maximum regenerative current when the duty ratio is maximized at the lower limit of the input voltage setting value Vdcref. For example, when the maximum value of the regenerative current is 1000 A, the lower limit voltage of the input voltage setting value is 750 V, the upper limit voltage is 900 V, and the maximum value of the duty ratio is 0.95, the regenerative resistance 8 ≦ 750/1000 × 0.95 = 0.71, the regenerative resistor 8 is selected to a value of about 0.7Ω. In this case, when the switching element SW is short-circuited due to a failure or miswiring of the switching element SW, a current determined by the input voltage Vdc1 and the regenerative resistor 8 via the switching element SW and the regenerative resistor 8 is chopper unit 10. Flowing into. When the input voltage Vdc1 is the lower limit voltage 750V and the regenerative resistor 8 is 0.7Ω, the regenerative current flows about 750 / 0.7 = 1071A, and when the input voltage Vdc1 is the upper limit voltage 900V, the regenerative current is 900/0. About 7 = 1286A flows. These values are 107% of the maximum regenerative current value at the lower limit voltage and 129% of the maximum regenerative current value at the upper limit voltage. On the other hand, since the overcurrent detection level is set higher than this, even if the switching element SW is short-circuited, the failure cannot be detected from the regenerative current value.

  In addition, when the switching element SW is opened due to a failure of the switching element SW or incorrect wiring, the regenerative current does not flow and the regenerative power cannot be absorbed. When using a plurality of chopper units 10 connected in parallel, even if the switching element SW of one chopper unit 10 is in an open state, the regenerative current value can be a current value that can be absorbed by another chopper unit 10. For example, the regenerative power absorbing device 6 continues to operate, but in the case of a current value that cannot be absorbed, the regenerative brake of the DC electric vehicle 5 cannot be used, and the DC electric vehicle 5 is regenerated before the overhead wire 3 becomes overvoltage. Therefore, it is impossible to detect an open failure of the switching element SW.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a regenerative power absorbing device that can easily detect an open / short circuit failure of a switching element constituting a chopper circuit. To do.

  The regenerative power absorbing device according to claim 1 of the present invention is connected in parallel to the DC power supply bus, and when the regenerative power from the motor is regenerated to the DC power supply bus, the regenerative power is generated by the regenerative resistor via the chopper circuit. A plurality of regenerative power absorbers that absorb the current, a current smoothing reactor provided on the output side of the chopper circuit, a current detector provided in each chopper circuit for detecting a chopper current, and a DC power supply bus A chopper current command value calculation unit that calculates a command value of chopper current per chopper circuit according to the deviation between the input voltage setting value and the input voltage, and the chopper current command value and each chopper current detection value A chopper duty ratio calculation unit that calculates the duty ratio of each chopper circuit according to the deviation, and the gate signal of the switching element of each chopper circuit so that this duty ratio is obtained. And a chopper gate signal generator for generating a deviation between the command value and the detected value of the chopper current is for detecting a failure of the switching element at or above the threshold.

  The regenerative power absorbing device according to claim 2 detects a short-circuit failure of the switching element of the chopper circuit when a state in which the current detection value of the chopper circuit−the current command value is larger than the threshold value continues for a certain period. .

  The regenerative power absorbing device according to claim 3 detects an open failure of the switching element of the chopper circuit when a state in which the current command value of the chopper circuit-current detection value is larger than the threshold value continues for a certain period. .

  As described above, according to the present invention, the command value of the chopper current of each chopper circuit is calculated from the deviation between the DC input voltage and the set value, and the deviation between the command value and the detected value of each chopper current is calculated. The chopper duty ratio is obtained from this, and the gate signal of the switching element of each chopper circuit is generated so as to become this duty ratio. If each switching element is normal, the command value of the chopper current and each detected value match. . However, when a failure occurs in the switching element in any of the chopper circuits, a large difference occurs between the command value of the chopper current and the detected value, and the deviation becomes greater than or equal to the threshold value. That is, when a short circuit failure occurs in the switching element of any chopper circuit, a chopper current larger than usual flows in the chopper circuit, and thus the state where the detected value of the chopper current−the command value is larger than the threshold value continues for a certain period. Therefore, it is possible to detect a short circuit failure of the switching element. Also, if an open circuit failure occurs in the switching element of any chopper circuit, the chopper current does not flow in that chopper circuit, so that the state where the command value-detected value of the chopper current is larger than the threshold value continues for a certain period of time. Thus, an open circuit failure of the switching element can be detected.

The best mode for carrying out the present invention will be described below with reference to the drawings. FIG. 1 is a control block diagram of a regenerative power absorbing device for a DC electric railway according to the best mode of the present invention, and FIG. 2 is a circuit configuration diagram of the regenerative power absorbing device. First, in FIG. 2, T1 and T2 are DC input terminals connected to an overhead line (DC power supply bus) 3 and input voltage from the overhead line 3 is input. The DC input terminals T1 and T2 include a regenerative current detector 9 and a reactor. A plurality of chopper units 15 are connected in parallel via L1. Each chopper unit 15 includes a capacitor C, a switching element SW, a freewheeling diode D, a current smoothing reactor L2 provided on the output side thereof, and a current detector 16 for detecting a chopper current. The switching element SW and the reactor L1 constitute a chopper circuit, and a regenerative resistor 8 is individually connected to the output side of the chopper circuit. The chopper circuit and the regenerative resistor 8 constitute a regenerative power absorption unit. A plurality of regenerative power absorption units are connected in parallel to the DC input terminals T1 and T2. The reason why the regenerative resistor 8 is individually provided and the current smoothing reactor L2 is provided is to control the current of the chopper circuit. The capacitor C and the reactor L1 constitute an LC filter as in the conventional case. In addition, the regenerative resistor 8 absorbs regenerative power due to heat generation.

  Next, in the control block diagram of FIG. 1, the DC input voltage Vdc1 from the DC input terminals T1 and T2 and its set value Vdcref are input to the comparator 18 of the chopper current command value calculator 17, and the deviation is proportionally integrated. A proportional-integral calculation is input to the calculation unit 19 to calculate a chopper current command value to be passed per one chopper circuit (chopper unit 15). This chopper current command value is input to the comparison unit 21 of the chopper duty ratio calculation unit 20 and compared with the detected value of each chopper current which is the output of the current detector 16 provided individually in each chopper circuit, and the deviation is The signal is input to the proportional-plus-integral calculation unit 22 and subjected to proportional-integral calculation, and the on / off duty ratio of the chopper circuit corresponding to the deviation is calculated. Each duty ratio is input to each chopper gate signal generation unit 23, and each chopper gate signal generation unit 23 generates a chopper gate signal so that the duty ratio of the corresponding chopper circuit becomes the calculated duty ratio. A chopper gate signal is supplied to the gate of the switching element SW of each chopper circuit.

  In the above-described regenerative power absorbing device, the command value of the chopper current of each chopper circuit is calculated from the deviation between the DC input voltage Vdc1 and the set value Vdcref, and the command value and the detected value of each chopper current are calculated. The chopper duty ratio is obtained from the deviation of the signal, and the gate signal of the switching element SW of each chopper circuit is generated so as to be this duty ratio. If each switching element SW is normal, the command value of the chopper current and each chopper Since the detected current values match and the regenerative power is absorbed by the heat generated by each regenerative resistor 8, the DC input voltage Vdc1 matches the set value Vdcref. Here, when a short circuit failure occurs in the switching element SW in any of the chopper circuits, a chopper current larger than normal flows in the chopper circuit, and a state where the detected value of the chopper current−the command value is larger than the threshold value is in a certain period. By continuing, a short circuit failure of the switching element SW can be detected. Further, when an open circuit failure occurs in the switching element SW in any of the chopper circuits, the chopper current stops flowing, and the state where the command value-detected value of the chopper current is larger than the threshold value continues for a certain period. An open fault can be detected.

  In the above-described best embodiment, the case where the present invention is applied to a regenerative power absorbing device for a DC electric railway has been described. However, a large number of motors are individually connected to a DC power source bus in factory equipment that is accelerated and decelerated by an inverter. And it can apply as a regenerative electric power absorption apparatus which absorbs the regenerative electric power from a motor with regenerative resistance, and can obtain an equivalent effect.

1 is a control block diagram of a regenerative power absorbing device for a DC electric railway according to the best embodiment of the present invention. FIG. 1 is a circuit configuration diagram of a regenerative power absorbing device for a DC electric railway according to an embodiment. FIG. It is a block diagram of the regenerative braking system of the conventional DC type electric railway. It is a circuit block diagram of the conventional regenerative power absorber. It is a control block diagram of the conventional regenerative power absorbing device.

Explanation of symbols

1 ... AC power supply 2 ... Substation 3 ... Overhead wire (DC power supply bus)
DESCRIPTION OF SYMBOLS 5 ... DC electric vehicle 8 ... Regenerative resistor 15 ... Chopper unit 16 ... Current detector 17 ... Chopper current command value calculating part 20 ... Chopper duty ratio calculating part 23 ... Chopper gate signal generation part T1, T2 ... DC input terminal

Claims (3)

  A plurality of regenerative power absorbers connected in parallel to the DC power supply bus and absorbing regenerative power by the heat generated by the regenerative resistor via the chopper circuit when regenerative power from the motor is regenerated to the DC power supply bus, and the chopper circuit According to the deviation between the set value of the input voltage from the DC power supply bus and the input voltage, the current smoothing reactor provided on the output side of the power supply, the current detector provided in each of the chopper circuits and detecting the chopper current. A chopper current command value calculation unit for calculating a chopper current command value per chopper circuit, and a chopper for calculating the duty ratio of each chopper circuit according to the deviation between the chopper current command value and each chopper current detection value A duty ratio calculation unit, and a chopper gate signal generation unit that generates a gate signal of a switching element of each chopper circuit so as to achieve this duty ratio. Regenerative power absorption device the deviation between the command value and the detected value of the chopper current and detects a failure of the switching element at or above the threshold.   2. The regenerative power absorbing device according to claim 1, wherein a short circuit failure of the switching element of the chopper circuit is detected when a state where the current detection value of the chopper circuit-current command value is larger than the threshold value continues for a certain period. .   2. The regenerative power absorbing device according to claim 1, wherein an open circuit failure of the switching element of the chopper circuit is detected when a state where the current command value of the chopper circuit-current detection value is larger than the threshold value continues for a certain period. .

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