JPH0470841B2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a main circuit in which a capacitor of an inverted L-type filter circuit inserted before an inverter that controls a main AC motor is connected in parallel to the inverter. In particular, the present invention relates to an induction disturbance suppression device for an electric vehicle for suppressing induction disturbances that occur during operation of an electric vehicle.

[Technical background of the invention and its problems]

A device shown in FIG. 7 is generally implemented as a main circuit configuration for driving an AC electric vehicle by obtaining DC power from a DC overhead wire. In this device, DC power is collected from a DC overhead wire 1A via a pantograph 1, and is transferred to an inverted L-shaped filter circuit having a main fuse 2, a current breaker 3, a high-speed circuit breaker 4, a reactor 5, and a capacitor 6. is supplied to a variable voltage/variable frequency (hereinafter referred to as VVVF) inverter 7, where it is converted into AC power with a voltage and frequency controlled to a predetermined value, and is then supplied to a main AC motor, such as an induction motor 8. .

In an electric vehicle control device with such a configuration,
Inductive disturbances caused by the current controlled intermittently by the switching elements constituting the inverter 7 become a problem. This is because the return current i containing high frequencies generated when the electric car operates in a wide frequency range from low frequency to high frequency, depending on the speed, flows in the power supply circuit, and the induction based on this harmonic current causes the railway to This is because various safety equipment such as traffic lights and railroad crossings may malfunction. For this reason, for example, the ripple current component included in the return current may be 50Hz or
In the case of the 60Hz commercial frequency band, it is said that it should be kept below 0.7A.

The inverted L-shaped filter circuit having the reactor 5 and capacitor 6 shown in FIG. 7 plays the role of suppressing harmonic components contained in the return current i. However, in order to suppress harmonic components in the commercial frequency band to below the above-mentioned value using this inverted L-shaped filter circuit, it is necessary to set the reactor 5 and capacitor 6 to considerably large values. Although devices with particularly high voltage resistance and large capacity are required, the space for installing them is often extremely limited. For example, in order to attenuate the ripple current with a frequency of 50 Hz by 10 dB, each constant of the inverted L-type filter circuit is determined by setting the inductance of the reactor 5 to L = 10 mH and setting the inductance of the capacitor 6 to 10 dB.
The capacitance of C becomes a large value of 4500 μF.

Furthermore, since the inverted L-type filter circuit has a resonance frequency determined by the constants of the reactor and capacitor that constitute it, ) coincides with this resonant frequency, a resonant current flows superimposed on the return current i, which may further amplify the induction disturbance. Therefore, in the past, in order to prevent a frequency that is multiples of the inverter frequency by the number of arms from passing through the resonant frequency, it was necessary to lower the resonant frequency by increasing the constants of the reactor and capacitor that constitute the inverted L-type filter circuit. for example,
If the minimum output frequency of the inverter is 2Hz,
Since the sixth frequency is 12 Hz, in order to make the resonant frequency of the inverted L-shaped LC filter less than 12 Hz, it is necessary to use a very large value of C=20000 μF, assuming L=10 mH.

As mentioned above, in conventional inverted L-type filter circuits, large-capacity reactors and capacitors are required to attenuate harmonic components contained in the return current, especially components below the commercial frequency band.
For vehicle use, it is disadvantageous in terms of weight, space, and economy.

[Purpose of the invention]

The present invention has been made in consideration of the above circumstances, and is aimed at reducing harmonic current contained in the return current during operation of an electric vehicle driven by an AC motor controlled by a VVVF inverter, particularly ripples below the commercial frequency band. It is an object of the present invention to provide an inductive disturbance suppressing device for an electric vehicle that can satisfactorily suppress current under more advantageous conditions in terms of weight, space, and economy.

[Summary of the invention]

To achieve the above object, the present invention provides an inductive disturbance suppressing device for an electric vehicle, which includes an input filter, a bandpass filter, an amplifier, a transformer, and an output overvoltage suppressing device. is an inverted L-type filter circuit with a reactor and a capacitor inserted in front of a variable voltage/variable frequency inverter that controls the main AC motor, and the capacitor is connected in parallel to the inverter.
The input filter inputs the voltage between the terminals of a capacitor, extracts the ripple voltage included in the voltage between the terminals, and then removes high voltage and high frequency pulse-like voltage components from the ripple voltage and outputs it. A pass filter inputs the output voltage of an input filter, extracts and outputs an AC voltage of a specific single or multiple selected frequencies from the input voltage, and an amplifier inputs the output voltage of the band pass filter. The transformer inputs an input voltage, adjusts the amplitude and phase of the input voltage, amplifies the power, and outputs it.The primary winding of the transformer is connected to the output side of the amplifier, and the secondary winding is an inverted L-shaped filter circuit. The output overvoltage suppressor is connected to the output terminal of the amplifier in series with the current path of the capacitor with a polarity opposite to the pulsating voltage of a specific frequency component. It protects the amplifier from overvoltage that sometimes occurs in the primary winding of the transformer.

Further, the bandpass filter can have a selected frequency corresponding to the resonant frequency and commercial frequency of the inverted L-shaped filter circuit.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows an embodiment of the present invention, and circuit components that are the same as those in FIG. 7 are given the same reference numerals and their explanations will be omitted. It should be noted that the circuit portions indicated by reference numerals 1 to 8 in FIG. 7 are represented as a main circuit M in FIG. The present invention corresponds to this main circuit M in which an inductive disturbance suppressing device S is added. The inductive disturbance suppression device S of FIG. 1 includes an input filter 9, an isolation transformer 10, a bandpass filter 11, an amplifier 12, a transformer 13,
The output overvoltage suppressing device 14 is also provided. The input filter 9 is connected to the capacitor 1 as shown in FIG.
6 and a resistor 17 connected in an inverted L shape, and a resistor 18 and a capacitor 19.
a primary low-pass filter 92 connected in an inverted L shape;
It consists of a voltage divider 93 consisting of a resistor 20 and a resistor 21. High-pass filter 91 is capacitor 6
The DC component is removed from the voltage between the terminals of , and the ripple voltage contained therein is taken out and applied to the reduction filter 92 . The low-pass filter 92 removes high-voltage, high-frequency pulsed voltage from the input voltage and converts it into the voltage divider 9.
Give to 3. Both filters 91 and 92 as a whole remove DC components and pulsed voltages having a frequency of 500 Hz or more from the input voltage, for example, as shown in FIG. The voltage divider 93 divides the voltage at an appropriate voltage division ratio as necessary for subsequent circuits.

The output voltage of input filter 9 taken out from voltage divider 93 is input to bandpass filter 11 via isolation transformer 10 . Bandpass filter 11
selectively extracts a specific frequency from the input voltage, for example, a voltage component of 50 Hz, which is the commercial frequency A, and a voltage component of the resonant frequency B of the inverted L-shaped filter circuit having the reactor 5 and capacitor 6, and extracts the voltage of other frequency components. It is assumed that this filter uses an operational amplifier for attenuation, and has frequency characteristics as shown in FIG.

The output voltage of the bandpass filter 11 is
2 is input. The amplifier 12 has a function of adjusting the amplitude and phase of the input voltage, and performs power amplification. The output voltage of this amplifier 12 is applied in series to the input side of an inverted L-type filter circuit having a reactor 5 and a capacitor 6 through a transformer 13 so that the polarity is opposite to the ripple voltage of the capacitor 6 at a specific frequency. It will be done. The transformer 13 may be connected to the negative side of the DC main circuit, or may be connected to the positive side, that is, the side where the reactor 5 is provided. By providing the amplifier 12 with a phase adjustment function,
Since the phase difference of the ripple voltage at a specific frequency between the input of the input filter 9 and the output of the amplifier 12 can be adjusted to zero, the input filter 9 and the bandpass filter 11 can adjust the amplitude without considering the phase characteristics at all. It becomes possible to determine constants based on the characteristics. FIG. 5 shows, as an example of the phase adjustment function of the amplifier 12, a waveform diagram when the phase of the output voltage b is delayed by 90 degrees with respect to the input voltage a.

A transformer 1 is connected to the output side of the amplifier 12 from the main circuit side.
Output overvoltage suppression device 1 including an overvoltage absorbing capacitor to suppress overvoltage entering through 3
Connect 4. A controlled power supply 15 is provided for the output overvoltage suppressor 14.

In the device described above, the presence of the transformers 10 and 13 allows the circuit portion between the secondary side of the transformer 10 and the primary side of the transformer 13, that is, the bandpass filter 11, the amplifier 12, the output The overvoltage suppression device 14 and the control power supply 15 can now be made into low voltage circuits.

The circuit parts 9 to 13 generate a voltage E t (the ripple voltage E _t ) of the same amplitude and opposite phase to a specific frequency included in the DC voltage of the main circuit, for example, the ripple voltage E _c (see Fig. 6a) in the commercial frequency band. (see Figure 6 b),
By superimposing it on the main circuit DC voltage E _i , both voltages E _c and E _t are canceled out, and it is possible to effectively suppress the ripple current of a specific frequency included in the return current i. can.

The overvoltage generated in the transformer primary winding circuit at the time of starting operation of the inverter 7, that is, at the time of initial charging of the capacitor 6, and at the time of an accident is suppressed by the output overvoltage suppressing device 14, and the amplifier 12 is protected.

In the embodiments described above, the case where harmonic current based on the ripple voltage of the commercial frequency band or the resonant frequency of an inverted L-type filter circuit is suppressed is explained as an example, but other harmonic ripple currents are suppressed. However, by changing the circuit constants of the input filter 9 and the bandpass filter 11, or by combining a plurality of filters with different circuit constants, it is possible to change the frequency characteristics.

〔Effect of the invention〕

As described above, according to the present invention, an inverted L
In the main circuit of an electric vehicle where a capacitor of a type filter circuit is connected in parallel to an inverter, the ripple current of a specific single or multiple frequency components included in the return current is reduced, and the resonance of the inverted L-type filter circuit is reduced. The frequency can be increased regardless of the output frequency of the inverter, and therefore, a small and lightweight inverted L-shaped filter circuit is used instead of using a large and large-capacity inverted L-shaped filter circuit with a reactor and capacitor. Therefore, it is possible to provide an induction disturbance suppression device for an electric vehicle that can be used as a main circuit of an electric vehicle with high reliability in which induction disturbances are suppressed.

[Brief explanation of drawings]

Fig. 1 is a circuit wiring diagram showing a configuration in which an inductive disturbance suppressing device for an electric car according to an embodiment of the present invention is added to the main circuit of an electric car, and Fig. 2 is a wiring diagram showing a specific example of the input filter in Fig. 1. Figure 3 is a characteristic diagram showing the frequency characteristics of the same input filter, and Figure 4 is a characteristic diagram showing the frequency characteristics of the same input filter.
5 is a voltage waveform diagram for explaining the phase adjustment function of the amplifier in the embodiment of FIG. 1,
Fig. 6 is a voltage waveform diagram showing the relationship between the ripple voltage of a specific frequency included in the DC voltage of the main circuit and the voltage for canceling it, and Fig. 7 is the configuration of a known electric vehicle main circuit to which the present invention is applied. FIG. 1A...DC overhead wire, 5...Reactor, 6...
Capacitor, 7... Variable voltage/variable frequency inverter, 8... Induction motor, 9... Input filter,
91...High-pass filter, 92...Low-pass filter,
10...Isolation transformer, 11...Band pass filter, 12...Amplifier, 13...Transformer, 14...
Output overvoltage suppression device.

Claims (1)

[Claims] 1. Input filter 9 and bandpass filter 11
This is an inductive disturbance suppressing device for an electric vehicle, which has an amplifier 12, a transformer 13, and an output overvoltage suppressing device 14. A capacitor 6 of an inverted L-type filter circuit having a reactor 5 and a capacitor 6 inserted before the inverter 7 is connected in parallel to the inverter 7, and the input filter 9 inputs the voltage between the terminals of the capacitor 6. , extracts the ripple voltage contained in the voltage between the terminals, and further removes high-voltage and high-frequency pulse-like voltage components from the ripple voltage and outputs it. The amplifier 12 inputs the output voltage of the bandpass filter 11 and extracts and outputs an AC voltage of a specific single or multiple selected frequencies from the input voltage. The transformer 13 has its primary winding connected to the output side of the amplifier 12, and its secondary winding connected to the inverted L-shaped filter circuit 5,
The output overvoltage suppressor 14 is connected to the output terminal of the amplifier 12 and connected to the current path of the inverter 7 in series with the polarity opposite to the pulsating voltage of a specific frequency component of the capacitor 6. An inductive disturbance suppression device for an electric vehicle that protects the amplifier 12 from overvoltage generated from the primary winding of the transformer 13 during the startup period and in the event of an accident. 2. The inductive disturbance suppression device for an electric vehicle according to claim 1, wherein the bandpass filter 11 has a selected frequency corresponding to the resonant frequency and commercial frequency of the inverted L-shaped filter circuits 5 and 6.