JPH0919161A - Power converter for AC electric vehicle drive - Google Patents

Abstract

(57) [Summary] [Structure] LC filters 21, 22 having a resonance frequency between the terminals of the secondary winding 2-2 of the main transformer 2 which is an integral multiple of 2 of the switch frequency of the three-level PWM converter 4. , 23 are installed. [Effect] In the three-level PWM converter, there are harmonics that are integral multiples of 2 of the switching frequency. By installing a plurality of LC filters having the same resonant frequency as the harmonic frequency between the terminals of the secondary winding 2-2 of the main transformer 2, the harmonic current is absorbed and the outflow to the overhead wire is prevented. Suppress.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an AC electric vehicle drive power converter using a three-level PWM converter / inverter.

[0002]

2. Description of the Related Art Conventionally, phase control by a thyristor bridge has been the mainstream in power converters for AC electric vehicles using semiconductor switching elements. FIG. 2 shows the result of a simulation in which harmonic currents flowing into the overhead line when phase control is used are obtained. The harmonic current having a frequency that is an odd multiple of the power supply frequency is present in the vicinity of the 20th to 30th orders, decreasing as the order of the higher harmonics increases. This harmonic current causes noise or the like on the communication line close to the overhead line, or causes a faulty operation of the signal track circuit due to the return current of the vehicle flowing to the rail, which causes an inductive failure. As a countermeasure against this, an LC filter with a resonance frequency that is an odd multiple of the power supply frequency is used on the sending side of the substation on the ground and in the main transformer on the vehicle.
It has been installed between the next windings. As an example of installing a third harmonic absorption filter on the ground, Yuji Kawazoe "AC Electric Vehicle Handbook" (Sho 46-12-1, Published by Electric Vehicle Research Association,
Pp. 185), and an example of the fifth and seventh harmonic absorption filters is described in "Science of Electric Vehicles, Sho 43-12.
"Monthly issue" (published by Electric Vehicle Research Institute Co., Ltd., pages 16 to 17) is introduced as the main circuit of the JNR (at that time) 711 series AC train.

[0003]

With respect to the power conversion device for an AC electric vehicle, a three-level PWM converter / inverter device using an IGBT as a semiconductor device is currently being developed due to the subsequent progress of the power semiconductor device. The component of the harmonic current flowing out to the overhead wire at this time is different from that of the conventional phase control.

FIG. 3 shows the spectrum of the single-phase PWM output voltage.

Considering the spectrum of the harmonics flowing from the 3-level PWM converter / inverter device to the overhead line, the apparent switching frequency doubles in the 3-level PWM control, so that ωs doubles. That is, there are integer multiples of the switching frequency and its sidebands in the spectrum. Moreover, if the two PWM control devices are operated with a carrier phase difference of 180 °,
Similarly, the switching frequency is apparently doubled.

In FIG. 4, 180 is used as the carrier wave of the two converters.
The simulation result of the harmonic current spectrum on the power supply side when the 3-level PWM converter / inverter device is operated with a phase difference of ° is shown. Due to the three levels and the fact that the carrier waves of the two converters have a phase difference of 180 °, there is an integer multiple of 4 and harmonics of its sidebands with respect to the converter switching frequency of 1350 Hz. I understand that.

Compared with the conventional harmonic spectrum of phase control, although the harmonic component for a power supply frequency of 50 Hz is greatly reduced, there are locally present frequency components of several kHz to several tens of kHz, which are unprecedented. It is considered that these may cause a new induction disorder.

[0008]

As a means for solving the above problems, a plurality of LC filters having a resonance frequency which is an integral multiple of the switching frequency of the converter are connected between the terminals of the main transformer secondary side winding. Then, an AC electric vehicle power converter having a function of suppressing the harmonic current flowing out to the overhead line is provided.

[0009]

FIG. 1 shows an AC electric vehicle power converter according to the present invention.

The overhead wire current taken in from the pantograph 1 is connected to the primary winding 2-1 of the main transformer 2, flows from the wheel 3 as a return current through the rail, and returns to the substation. A three-level PWM converter 4 is provided on the secondary winding 2-2 of the main transformer 2.
Are connected and converted from AC to DC. 3 level PW
A filter capacitor 5 is provided on the DC side output of the M converter.
Connected to the 3-level PWM inverter 7 via 6
The AC output subjected to VVVF control by the level PWM inverter 7 is connected to the three-phase induction motor 8 to drive the vehicle.

The LC filters 21, 22, 23 proposed in the present invention are connected between the terminals of the secondary winding 2-1 of the main transformer 2.

Since FIG. 1 shows the configuration of one 3-level PWM converter / inverter device, an integer multiple of 2 of the switching frequency of the 3-level PWM converter 4 appears remarkably as the harmonic current flowing out to the overhead line.

Since the higher harmonics have smaller amplitudes, the higher harmonics of the harmonics have resonance frequencies of the LC filters 21, 22, and 23, which are twice, four times, and six times the switching frequency of the three-level PWM converter 4. To do. Therefore, the switching frequency of the 3-level PWM converter 4 is set to 1350H.
If z, the resonance frequency of the LC filter is 1350 × 2 = 2700 Hz for the LC filter 21,
2 is 1350 × 4 = 5400 Hz, and the LC filter 23 is 1350 × 6 = 8100 Hz.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT FIG. 5 shows the present invention as a three-level PWM converter.
This is an example applied to an AC electric vehicle composed of two inverter devices.

The main transformer 11 has two sets of secondary windings 2-2, each of which is connected with a 3-level PWM converter 4, filter capacitors 5, 6, a 3-level PWM inverter 7, and a 3-phase induction motor 8. Has been done.

Here, if the two three-level PWM converters 4 are operated with the phase difference of the carrier wave shifted by 180 °, the harmonic current flowing out to the overhead wire will be the three-level PWM converters 4.
Is an integer multiple of 4 of the switching frequency of. Therefore, 3
The switching frequency of the level PWM converter 4 is set to 13
If the frequency is 50 Hz, the resonance frequency of the LC filter is LC
The filter 21 becomes 1350 × 4 = 5400 Hz, the LC filter 22 becomes 1350 × 8 = 10800 Hz, and the LC filter 23 becomes 1350 × 12 = 15840 Hz.

[0017]

EFFECTS OF THE INVENTION According to the present invention, it is possible to suppress the outflow of the harmonic current of the three-level PWM converter / inverter device to the overhead line, and to reduce the inductive interference given to the adjacent communication lines and signal track circuits. A device can be provided.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of an embodiment of the present invention.

FIG. 2 is an explanatory diagram of a harmonic spectrum of phase control.

FIG. 3 is an explanatory diagram of a PWM control harmonic spectrum.

FIG. 4 is an explanatory diagram of a PWM control harmonic spectrum.

FIG. 5 is an explanatory diagram of a second embodiment of the present invention.

[Explanation of symbols]

1 ... Pantograph, 2, 11 ... Main transformer, 2-1 ... Main transformer primary winding, 2-2 ... Main transformer secondary winding, 3 ... Wheel,
4 ... 3-level PWM converter, 5, 6 ... Filter capacitor, 7 ... 3-level PWM inverter, 8 ... 3-phase induction motor, 21, 22, 23, 31, 32, 33 ... LC filter.

Claims (2)

[Claims] 1. A power supply is supplied from an AC overhead wire to a primary winding of a main transformer, and the main transformer has a pair of secondary windings. A set of three-level PWM converter / inverter device is connected, and the three-level P
In an AC electric vehicle drive power converter in which a WM converter operates at a switching frequency, the resonance frequency is switched between terminals of a secondary winding of the main transformer to suppress a harmonic current flowing to an overhead wire. An AC electric vehicle driving power conversion device comprising a plurality of LC filters connected in parallel, each of which has an integer multiple of the frequency. 2. The main transformer according to claim 1, wherein the main transformer has two sets of secondary windings, and one set of the three-level PWM converters is provided for each of the two sets of secondary windings. An inverter device is connected to the two sets of the three-level PWM
In a power converter device for driving an AC electric vehicle, wherein the converter operates at a switching frequency and the phase difference of the carrier waves of the two sets of three-level PWM converters is 180 °, the two sets of secondary windings of the main transformer are An AC electric vehicle drive power converter device having a plurality of LC filters connected in parallel between respective terminals in order to suppress harmonic currents flowing to the overhead line, the resonance frequency being an integral multiple of 4 of the switching frequency. .