JP2795891B2 - Power failure detection device for power converter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Purpose of the Invention] (Industrial application field) The present invention relates to a power failure detection device for detecting a power failure of a power conversion device.

(Prior Art) In general, a power converter for an electric vehicle has a configuration shown in FIG. 4, and feeds power from an overhead line 1 to a primary side of a main transformer 4 via a pantograph 2 and a circuit breaker 3. Connected. A converter 6 is connected to the secondary side of the main transformer 4 via an AC reactor 5, and the AC power is converted into DC by the converter 6. A filter capacitor 7 and a VVVF inverter 8 are connected in parallel to the output of the converter 6, and an induction motor 9 is connected to the output of the VVVF inverter 8.

Conventionally, in such a general power converter,
A power failure detection device 11 for detecting a power failure by detecting the overhead line AC voltage by the tertiary winding 10 of the main transformer 4 is connected.
And this conventional power failure detection device 11 was simply constituted by a no-voltage detection device.

(Problems to be Solved by the Invention) However, in such a power failure detection device of a conventional power conversion device, when only a plurality of electric vehicles without a power regenerative brake run in the same power section, power failure detection is performed. A power failure detection can be performed by a no-voltage detection device as a device. However, when a plurality of electric vehicles using a power regenerative brake are traveling in the same power supply section, only such a no-voltage detection device is used. There are the following problems with the power failure detection device.

In other words, as shown in FIG. 5, when two vehicles equipped with a power regeneration brake are running in the same power section, one vehicle 12 is a regenerative vehicle, and the other vehicle 13 is a power running vehicle. When the power supplied from the substation 14 causes a power outage due to the opening operation of the circuit breaker 15, the power generated by the regenerative vehicle 12 and the power consumed by the power running vehicle 13 are balanced and the operation is performed for a certain period after the power failure occurs. However, there is a problem that all electric vehicles cannot be stopped urgently when a power failure occurs.

The present invention has been made in view of such a conventional problem, and is an electric power that can reliably generate a power failure even when a regenerative vehicle and a power running vehicle are running simultaneously in the same power supply section. An object of the present invention is to provide a power failure detection device for a conversion device.

[Means for Solving the Problems] A power failure detection device for a power conversion device according to the present invention includes a zero-cross comparator that detects a zero-cross point at which an AC power supply voltage changes from positive to negative or from negative to positive. A first counter that receives a zero-cross signal of a zero-cross comparator as a clear input via a frequency divider, and receives a clock from a signal from an oscillator having a frequency N times the power supply voltage frequency as a clock input; A second counter having a clock input of a signal from an oscillator having a frequency N times higher than the voltage frequency, and an output signal of the second counter having a clock input;
A first multivibrator that detects a timing at which a clock input signal changes from 'H' to 'L' or 'L' to 'H' and outputs 'H' or 'L' for a fixed period; While the output signal of the counter is at 'H' or 'L', the timing at which the output signal from the first multivibrator changes from 'H' to 'L' or from 'L' to 'H' is detected. A second multivibrator for outputting a power failure detection signal.

(Operation) In the power failure detection device for a power conversion device according to the present invention, each of the first and second counters is provided for each zero-cross point where the voltage frequency of the AC power supply changes from positive to negative or for each zero-cross point where the voltage frequency changes from negative to positive. Clears and starts counting the pulse signals from the respective oscillators. Therefore, when the power supply voltage is normal, the first counter and the second counter output a signal having a constant minute phase difference.

However, when the power supply voltage stops, the power is not input to the zero cross comparator, and the first and second counters continue to count the clock frequency from the respective oscillators. On the other hand, a sine wave generated based on a signal from an oscillator having a frequency N times a frequency slightly larger than the power supply voltage frequency is input to the zero-cross comparator, but the first counter corresponding to the power supply voltage frequency receives a sine wave. The zero-cross signal is not input by the frequency divider for the division period, so that the phases of the output signals of the first and second counters input to the first and second multivibrators are shifted. Therefore, the first multivibrator outputs the 'H' or 'L' output for a certain period of time when the 'H' or 'L' signal is input in synchronization with the clock signal given from the second counter. However, since the phase of the clock input from the first multivibrator is out of phase with the signal supplied from the first counter to the second multivibrator, the input from the first counter becomes' H An event occurs in which the clock input from the first multivibrator changes during the period of 'or' L '.

Therefore, by outputting a power failure detection signal from the second multivibrator at this timing, a power failure of the AC power supply can be notified.

(Example) Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a circuit block diagram of one embodiment of the present invention, which is used as a power failure detection device 11 in FIG. 4 shown as a general power conversion device.

This power failure detection device is provided with a tertiary winding 10 of the main transformer 4.
The AC power supply voltage Es obtained from is input to the zero-cross comparator 16, a counter 17 having the output from the zero-cross comparator 16 as a clear input, and the output from the zero-cross comparator 16 divided by m by the frequency divider 18. A counter 19 having a signal as a clear input and multivibrators 20 and 21 having outputs of the counters 17 and 19 as inputs are provided.

(60 + α) · N
The pulse signal is given from the oscillator 22 of the
The 19 clock input is supplied with a pulse signal from the oscillator 23 of 60 · N Hz. Here, α is an arbitrary minute value, and N is a value determined by a sine wave ROM as described later.

The output of the counter 17 is connected to a sine wave ROM 24, and a current command value sine wave described later as an output of the sine wave ROM 24 is input to one input of a multiplier 25, and the other input of the multiplier 25 is a wave. A high value command Im ^* is given, and a current command value Is ^* is calculated by the multiplier 25 to be a command value of the converter 6.

The Q output FG of the multivibrator 20 is given to the clock input of the multivibrator 21, and the Q output of the multivibrator 2 becomes the power failure detection signal PFR.

The operation of the power failure detection device of the power converter having the above configuration will be described below.

The power supply voltage Es detected from the tertiary winding 10 in FIG.
Is input to a zero-cross comparator 16 that detects a zero-cross point that changes from positive to negative.

Each time the output of the zero cross comparator 16 becomes “H”, the counter 17 that determines the electrical angle of the AC current command value of the converter 6 is cleared.

In this case, a clock obtained by multiplying the frequency slightly higher than the power supply frequency by N times is input to the counter 17, and a value obtained by equally dividing the horizontal axis of one cycle of the sine wave into (N-1) as shown in FIG. Is stored, the current command value sine wave can be obtained. Therefore, a current command value Is ^* is obtained by multiplying the output from the sine wave ROM 24 by a peak value command Im ^* by the multiplier 25, and this is used as a current command for the converter 6 to perform converter control.

An oscillator 22 is connected to the clock input of the counter 17.
From (60 + α) · N Hz, the frequency of the power supply voltage is determined by the power supply frequency transmitted from the substation 14 if the substation 14 is normal as shown in FIG. You. That is, if the power supply frequency is 60 Hz, the "H" signal is input from the zero-cross comparator 16 every 60 Hz to the clear input of the counter 17 and the counter 17 is cleared, and its output is corrected every 60 Hz. However, when the circuit breaker 15 is opened at the substation 14, the frequency of the AC overhead line 1 becomes (60 + α) Hz which is the frequency of the current command value sine wave.

Separately, the counter 19 has 60 NHz from the oscillator.
Is input to the clock input, and at the same time, a signal obtained by dividing the output from the zero-cross comparator 16 by m by the frequency divider 18 is input to the clear input. Therefore, the output of the counter 19 is corrected so as to be synchronized once every m cycles of the power supply voltage.

The output signals PA11, PB11 of the counters 17, 19 are zero-cross points corresponding to a 360-degree electrical angle of a 60-Hz sine wave from negative to positive or from positive to negative. Then, these signals PA11, PB1
1 is output as a square wave with a duty ratio of 1: 1 as shown in FIG.

Therefore, as long as the power supply voltage is normal and the counter 17 can correct every 60 Hz with the output of the zero-cross comparator 16,
When the falling edges of PA11 and PB11 have a small fixed time difference, PA11 becomes (60+) when the power supply voltage disappears and the counter 17 determines its own frequency by counting up.
α) Hz and PB11 become 60 Hz, and their falling timings are shifted, and the differences δ1, δ2, δ3,.
As shown in ZD, it increases with each cycle.

Therefore, now, for a certain period T1 from the fall of PA11, 'L'
When the output FG of the multivibrator 20 is 'L',
If power line abnormality signal PFR is set to be output when PB11 is “H”, power failure detection can be performed. In other words, the multivibrator 21 outputs the signal from the counter 19
When the output FG of the multivibrator 20 rises during the period T2 when the output FG of the multivibrator 20 rises while the PB11 is 'H', the output PFR of the multivibrator 21 becomes 'H'. The power outage is detected.

In this way, when the power supply voltage from the overhead line 1 is normal, the counters 17 and 19 are referenced based on the frequency of this power supply voltage.
The phase difference of the output square wave is kept constant, and when the power supply voltage is no longer supplied, oscillators 22 and 23 with different frequencies are used.
The outputs of counters 17 and 19 are given by the pulse signal from
By detecting the occurrence of a difference between the output phases of the counters 17 and 19, a power failure of the overhead power supply can be detected.

[Effect of the Invention] As described above, according to the present invention, the first and second counters which count the signals from the oscillators having their own frequencies by using the zero-cross point of the AC power supply voltage as the clear input by the zero-cross comparator. While the AC power supply is standing, an output of a certain minute phase difference is given to the first multivibrator and the second multivibrator, respectively, and thus the clock signal from the first multivibrator is changed to the 'H' of the second multivibrator. Or 'L'
During the input period, it does not change from 'H' to 'L' or 'L' to 'H', the AC power supply is stopped, and the first and second counters are each supplied from an oscillator of its own frequency. The signals start to count so that their output signals are out of phase, from the first multivibrator when the 'H' or 'L' input is given to the second multivibrator from the second counter. In this case, the clock input is changed from 'H' to 'L' or 'L' to 'H', and this timing is detected to detect a power outage. Even when the regenerative vehicle and the power running vehicle are running simultaneously in one feeding section, the power failure of the power supply can be reliably detected.

[Brief description of the drawings]

FIG. 1 is a circuit block diagram of one embodiment of the present invention, FIG. 2 is a signal waveform diagram of each part in the above embodiment, FIG. 3 is a waveform diagram for explaining the operation of the sine wave ROM described above, and FIG. Circuit block diagram of a general electric vehicle power converter, FIG.
The figure is an explanatory diagram showing a state in which a regenerative vehicle and a power running vehicle run simultaneously in one feeder section. 1 ... overhead wire, 2 ... pantograph 4 ... main transformer, 6 ... converter 8 ... VVVF inverter 9 ... induction motor, 10 ... tertiary winding 11 ... power failure detection device 16 ... zero cross comparator 17 ... Counter 18 Multiplier 19 Counter 20 Multivibrator 21 Multivibrator 22 Oscillator 23 Oscillator 24 Sine-wave ROM

──────────────────────────────────────────────────続 き Continued on the front page (58) Fields surveyed (Int.Cl. ⁶ , DB name) B60L 3/00-3/12 B60L 9/00-9/32 B60L 13/00 B60L 15/00-15 / 42 H02H 3/46 H02H 3/24 H02M 7/48

Claims (1)

(57) [Claims] 1. A zero-crossing comparator for detecting a zero-crossing point of an AC power supply voltage that changes from positive to negative or from negative to positive. A zero-crossing signal of the zero-crossing comparator is input as a clear input via a frequency divider, and a power supply voltage frequency N A first counter having a clock input from a signal from an oscillator having a double frequency; a clear input having the zero cross signal; and a clock input having a signal from an oscillator having a frequency N times higher than the power supply voltage frequency. A second counter, and an output signal of the second counter as a clock input, and detects a timing at which the clock input signal changes from 'H' to 'L' or from 'L' to 'H' and only for a certain period A first multivibrator that outputs 'H' or 'L', and the first multivibrator while the output signal of the first counter is 'H' or 'L' A second multivibrator that detects the timing at which the output signal from the inverter changes from 'H' to 'L' or from 'L' to 'H' and outputs a power failure detection signal; and Power failure detection device.