JP2003189631A - Power failure detector of power conversion circuit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve reliability by detecting power failure promptly in a simple way. <P>SOLUTION: In a power converter 6 connected to a DC power supply 1 for providing a motor load (induction machine) 7 with power, a power failure detecting circuit 24 is provided, and the power failure can be detected promptly even when the load of the power converter 6 is light. The power failure detecting circuit 24 is composed of an input power arithmetic unit 25 for calculating input power of the power converter 6 from its input current and a terminal voltage of a capacitor 5, an output power arithmetic unit 26 for calculating output power of the power converter 6 from a torque current obtained through current detectors 10 to 12 and an arithmetic unit 14 and a motor voltage command value calculated from an arithmetic unit 19, and a logical circuit 27 for determining the generation of power failure when the input power is zero and the output power is a prescribed level or larger or a prescribed negative level or smaller. <P>COPYRIGHT: (C)2003,JPO

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power converter for converting a direct current into an alternating current or direct current, and more particularly, to a power failure of a power converter circuit which is preferably mounted on a DC electric vehicle. It relates to a detection device. 2. Description of the Related Art In a power converter mounted on a DC electric vehicle, a power failure of a power supply is detected and its operation is stopped to prevent overvoltage and overcurrent of the power converter when passing through a section. is necessary. As a conventional power failure detection method of this type, for example, the following method is known. It is detected when the power supply voltage value deviates from a predetermined value range. It is detected when the voltage value of the input capacitor deviates from a predetermined value range. However, in the above-described method, when the load of the power converter is light,
There is a problem that it is sometimes difficult to quickly detect a power failure of the power supply. Therefore, the object of the present invention is to
An object of the present invention is to make it possible to quickly detect a power failure of a power supply even when the load of the power converter is light. [0004] In order to solve such a problem, according to the first aspect of the present invention, a power converter is connected to a DC power supply via a filter comprising a reactor and a capacitor and supplies power to a motor load. And a current detector for detecting the output current, and a current controller for adjusting and calculating the current detection value so as to match the command value, and adding the output of the current controller as a correction amount to obtain a motor voltage command value. For a power converter circuit that controls the power converter in order to obtain
An input power calculator for calculating the input power of the power converter from the current flowing through the reactor and the voltage across the capacitor, and the power converter based on the output from the current detector and the motor voltage command value. An output power calculator for calculating output power, and a detection circuit for detecting occurrence of a power failure when the calculated input power is zero and the calculated output power is equal to or more than a positive predetermined value or equal to or less than a negative predetermined value. Are provided. FIG. 1 is a block diagram showing a first embodiment of the present invention. In the figure, 1 is a DC power supply that is supplied between the overhead wire and the rail shown in the figure, 2 is a pantograph,
3 is a rail, 4 is a filter reactor, 5 is a filter capacitor, 6 is a VVVF (variable voltage variable frequency) inverter for converting DC to three-phase AC, and 7 is an induction motor (I
M) and 8 are current detectors for detecting an input current, 9 is a voltage detector for detecting a voltage across the filter capacitor 5, and 1
Reference numerals 0, 11 and 12 denote current detectors for detecting three-phase currents of the induction motor 7, and reference numeral 13 denotes a control device for controlling the VVVF inverter 6. The control device 13 includes a torque current calculation circuit 14 for calculating a torque current from detection signals of the current detectors 10 to 12, a torque current command device 15, a motor voltage command device 16, and a torque current calculation circuit 14. Subtractor 1 for calculating the deviation between the output and the command value from torque current command device 15
7. A current regulator 18 for adjusting the output of the subtracter 17 to calculate the correction amount of the motor voltage, and a motor for calculating the motor voltage command by adding the output of the current regulator 18 to the output of the motor voltage commander 16. A voltage command calculator 19, a divider 20 for calculating a modulation rate by dividing a motor voltage command by a filter capacitor voltage, and a sine wave generator (sin) 21 for generating a sine wave serving as a reference for controlling the VVVF inverter 6. ,
A modulation wave calculator 22 for calculating a modulation signal by calculating a product of a modulation rate and a sine wave, and a VVVF inverter 6 based on the modulation signal
And a PWM arithmetic unit 23 that generates a gate drive signal for. Reference numeral 24 denotes an input power calculator 25 for calculating the product of the input power detected by the current detector 8 and the capacitor voltage detected by the voltage detector 9 to generate the input power of the VVVF inverter 6. An output power calculator 26 for calculating the product of the torque current calculated by the torque current calculator 14 and the motor voltage command value calculated by the motor voltage command calculator 19 to generate the output power of the VVVF inverter 6; When the input power calculated by the calculator 25 is zero and the output power calculated by the output power calculator 26 is equal to or more than a predetermined positive value or equal to or less than a predetermined negative value, the output of the PWM calculator 23 is stopped. Signal (power failure detection signal)
Is shown in FIG. In the power failure detection circuit 24, when the DC power supply 1 is powered down while the VVVF inverter 6 is performing a power running operation, the output of the input power calculator 25 becomes zero, but the output of the output power calculator 26 becomes Since a positive operation value is output, the logic circuit 27 outputs a power failure detection signal. Also, V
If the DC power supply 1 loses power while the VVF inverter 6 is performing a regenerative braking operation, the output of the input power calculator 25 becomes zero, but the output of the output power calculator 26 outputs a negative calculation value. The power failure detection signal is output from the logic circuit 27 in the same manner as described above. That is, in the conventional power failure detection circuit, when a power failure occurs when the power running power is small (at a light load), the voltage of the filter capacitor 5 gradually decreases. In some cases, it took time to do so. In particular, when a power failure occurs due to passage of a section, the power failure cannot be detected before the passage of the section, and an excessive input current flows due to re-supply of power, or the filter capacitor 5 is charged with this current, and the VVVF
An excessive voltage was sometimes applied to the input of the inverter 6. On the other hand, according to the present invention, a power failure is determined based on the fact that the input power of the VVVF inverter 6 becomes zero and the powering power or the regenerative power is generated at the output. The VVVF inverter 6 can be stopped immediately by detecting a power failure. Here, the power failure is detected by the presence of the power running power or the regenerative power. Alternatively, the power failure may be detected by the presence of the power running command or the regenerative brake command to the VVVF inverter 6. According to the present invention, it is possible to quickly detect a power failure by using a detector originally included in the power conversion device without complicating a circuit configuration for detecting a power failure. It is.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a configuration diagram showing an embodiment of the present invention. [Description of Signs] 1 ... DC power supply 2 ... Pantograph 3 ... Rail 4 ... Filter reactor 5 ... Filter capacitor 6 ... VV
VF (variable voltage variable frequency) inverter, 7 ... induction motor (IM), 8, 10, 11, 12 ... current detector, 9 ...
Voltage detector, 13 ... VVVF inverter control device, 14
... Torque current calculation circuit, 15 ... Torque current commander, 16
... Motor current commander, 17 ... Subtractor, 18 ... Current regulator, 19 ... Motor voltage command calculator, 20 ... Divider, 21
... Sine wave generator (sin), 22 ... Modulation wave calculator, 23
... PWM operation unit, 24 ... power failure detection device, 25 ... input power operation unit, 26 ... output power operation unit, 27 ... logic circuit.

Claims (1)

Claims: 1. A power converter connected to a DC power supply via a filter including a reactor and a capacitor to supply power to a motor load, a current detector for detecting an output current of the power converter, and a current detection value for the current converter And a current regulator that performs an adjustment operation so as to match the command value.The power converter circuit that controls the power converter by obtaining a motor voltage command value by adding the output of the current controller as a correction amount. An input power calculator for calculating the input power of the power converter from the current flowing through the reactor and the voltage across the capacitor; and the power converter based on the output from the current detector and the motor voltage command value. An output power calculator for calculating the output power of the input power, wherein the calculated input power is zero, and the calculated output power is equal to or more than a positive predetermined value or equal to or less than a negative predetermined value. Power failure detecting apparatus of a power conversion circuit which is characterized by providing a detection circuit for detecting a power failure.