JPS63112233A - Regenerative power absorbing device - Google Patents

Abstract

PURPOSE:To absorb the excessive regenerative power with an inexpensive device by connecting a serial circuit of multiple capacitors between a feeder line and the ground to divide the line voltage and connecting serial circuits of current interrupting means and resistors in parallel with individual capacitors. CONSTITUTION:A serial circuit of an upper capacitor 30A and a lower capacitor 30B as input capacitors is connected between a feeder line of the high voltage, e.g., 1,500V, and the ground to divide the line voltage into two. Load resistors 31-34 are connected in series with choppers 41-44 as four pairs of current interrupting means respectively, two pairs out of these four pairs of the serial circuits are connected in parallel with the upper capacitor 30A and the other two pairs are connected in parallel with the lower capacitor 30B respectively. The two pairs of the choppers 41, 42 are operated with a phase difference of 180 deg., and the two pairs of the choppers 43, 44 with a phase difference of 180 deg. respectively. A phase difference of 90 deg. is set between the upper chopper 41 and the lower chopper 43.

Description

[Detailed description of the invention] [Technical field to which the invention pertains] The present invention is a device for absorbing surplus regenerative power generated when a DC electric vehicle performs regenerative operation.

In particular, the present invention relates to a regenerative power absorption device suitable for high voltage circuits.

[Prior art and its problems]

In recent years, DC electric vehicles have increasingly used a chopper to convert the DC power taken in from the feed line to rotate the DC motor, or an inverter to convert it to variable voltage and variable frequency AC power to rotate the AC motor. Therefore, when this DC electric car decelerates or runs downhill, regenerative braking operation converts the energy held by the DC electric car into electrical energy and returns it to the power source. has become easier.

FIG. 4 is an explanatory diagram showing a regenerative braking system for a DC electric vehicle. In FIG. 4, a substation 2 is comprised of a transformer and a rectifier, and supplies DC power output from the substation 2 to DC electric cars 5 and 6 via a power supply line 4. Therefore, these DC electric cars 5, 6 take in this DC'1 power from pantographs 5P, 6P, rotate DC motors 5M, 6M via switches 58, 68, and then discharge it to the ground via wheels and rails. The electric car is driven by However, DC motor 5M, 5
The illustration of a chopper and the like for controlling M is omitted.

In FIG. 4, if one of the DC electric cars 5 is in the 2nd line operation and the other DC electric car 6 is in the regenerative operation, the 1st electric car 5 in the 1st line is connected to the substation 2. Since the sum of the current 2 and the current 6 regenerated from the electric car 6 results in continuous operation, the power output by the substation 2 is calculated by subtracting the power regenerated from the electric car 6. Since the value is sufficient, it is possible to save energy.

However, as mentioned above, the electric car 5
When the electric power required by the substation 2 decreases or the electric power regenerated from the electric vehicle 6 during regenerative operation increases, the current 2 outputted from the substation 2 decreases correspondingly and finally becomes zero. Even if the output of the substation 2 becomes zero, if the electric power regenerated from the electric car 6 is not consumed by the running 1st electric car 5, this surplus regenerated power will cause an increase in the voltage of the feed line 4, etc. In order to prevent this from occurring, a regenerative power absorption device 3 is connected to the power supply line 4.

If there is a surplus in the regenerative power, it is absorbed into the regenerative power absorption device 3. That is, in FIG. 4, the output current 2 from the substation 2 is zero, and the DC electric car 5 is the DC electric car 6.
The regenerative braking system shown in Figure 1 operates in a balanced manner as the electric current I3 regenerated from the DC electric car 6 is further absorbed into the regenerative power absorption device 3. The circuit voltage of a DC electric car that can continue to operate is relatively low voltage.
For example, there are those that use DC600 volts or DC750 volts, and those that use relatively high voltage, such as DC15
There are some that are over 00 volts. .

FIG. 5 is a circuit diagram showing a conventional example of a regenerative power absorption device used in a low voltage circuit, and the main circuit of this device is as follows:
Input capacitor 9 connected between feed line 4 and ground
This is a series circuit of a plurality of sets of resistors connected in parallel to the input capacitor 9 and a current interrupting means, and in FIG. 5, it is composed of four sets of series circuits. That is, numerals 11 to 14 are load resistors, respectively, and numerals 15 to 18 are choppers as current intermittent means, respectively. Also,
a voltage regulator 8 that inputs the deviation between the voltage Vc of the input capacitor 9 and the voltage Vs set by the voltage setter 10;

A control circuit for the regenerative force absorbing device is formed by the phase shifter 7 which inputs the output signal v8 of the voltage regulator 8 and outputs separate operation signals B1 to B4 to the four choppers 15 to 18. ing.

In the conventional circuit shown in FIG. 5, when the voltage Vc of the input capacitor 9 rises due to the inflow of the regenerative current I3 from the power supply line 4 and becomes higher than the set voltage Vs, the voltage regulator 8 Since the deviation from Vs is inputted and a control signal 8 that makes this input deviation zero is sent to the phase shifter 7, the phase shifter 7 generates a separate on/off signal corresponding to this control signal V8. The off signals B1 to B4 are sent to each chopper 15.
~ 18, the switch elements that make up each chopper 15-18 turn on and off to adjust the amount of regenerated power consumed by the load resistors 11-14, and set the voltage of the feed line 4. It is controlled to be the value Vs. Here, the set value VS is.

Usually, a value slightly higher than the sending voltage from the substation 2 is selected.

Inside the phase shifter 7, there are four sets of reference signal generating circuits that output triangular wave reference signals A1 to A4 corresponding to the number of chisel waves 15 to 18K, and the triangular wave reference signals A1 to A4. Four sets of comparators are provided which compare the magnitude relationship between A4 and the control signal V8 outputted from the voltage regulator 8, and determine the conductivity of each circuit separately.

Signals B1 to B4 output from these comparators are given to choppers 15 to 18, and these choppers 15
The current is intermittent by the operation of ~1B.

In the conventional example circuit shown in FIG.
18 is used, so that these four sets of choppers operate with the same phase difference (in the case of four sets, the operations are shifted by 1/4 cycle,
That is, the triangular wave reference signals A1 to A4 are each given a phase difference of 90 degrees in electrical angle.

FIG. 6 is an operation waveform diagram showing the operation of each part of the conventional circuit shown in FIG. The shifted triangular wave reference signal A1 to A40 waveforms are shown in Fig. 6 (E), (E), ()),
(a) shows the waveforms of the signals B1 to B4 output from the phase shifter 7 to operate the chopper, and Fig. 6 shows the changes in the regenerative current generator 3 flowing into the regenerative power absorption device. Each waveform of the voltage Vc of the input capacitor 9 is shown.

As is clear from FIG. 6, the four sets of triangular wave reference signals A1 to A4 have a phase difference of 174 periods, that is, 90 degrees, and therefore the phase shifter 7 sends them to the respective choppers 15 to 18. The operating signals B1 to B4 applied to the respective terminals also have a phase difference of 90 degrees.

If it is assumed that the choppers 15 to 18 intermittent the current without delay in response to the operation signals B1 to B4 given to the choppers 15 to 18, the waveform of the current 115 flowing through the chip 15 is the signal that operates the choppers 15. It has the same waveform as B1. Similarly, the current 116 +117 yllg flowing through the other choppers 16, 17, 18 and the corresponding operation signals B2, 83, B4 have the same waveform. Therefore, the waveform of the regenerative current I3 flowing into the regenerative power absorption device is current 1
15 to 118, that is, the operation signal B1 to
B4 is synthesized (see Fig. 6 (1)), and the current ripple is small.Furthermore, the voltage Vc of the input capacitor 9 has the waveform shown by the solid line (see Fig. 6).

When the phase difference operation is not performed, that is, when the in-phase operation is performed (indicated by the broken line in Fig. 6), the voltage ripple has the advantage of being small.

FIG. 7 is a circuit diagram showing an example of a switching element constituting a chopper, and shows a case where a gate turn-off thyristor (hereinafter abbreviated as a GTO thyristor) is used as a switching element. 151 is a GTO thyristor, 152 is a snubber diode, 153 is a snubber resistor, and 1
54 is a snubber capacitor.

When the circuit voltage of the feed line 40 is low, for example 750 volts, a GTO thyristor with a withstand voltage of 2500 volts is used, but if the circuit voltage is high, for example 15
If it is 00 volts, then GT with 4500 volts withstand voltage.
An O thyristor will be selected. Assuming that the capacity of the regenerative power absorption device 3 is the same regardless of the circuit voltage, the value of the regenerative current flow 3 flowing into the regenerative power absorption device 3 is half of that in the 750 volt system for a 1500 volt system. Since G is sufficient as a switching element,
If the current capacity of the TO thyristor 151 is the same regardless of the withstand voltage value, the number of choppers connected in parallel with the input capacitor can be halved.

FIG. 8 is a main circuit connection diagram showing a conventional example of a regenerative power absorption device used in a high voltage circuit.

Input capacitor 2 connected between feed line 4 and ground
A series circuit of a load resistor 21 and a chopper 23 as a current intermittent means and a series circuit of a load resistor 22 and a chopper 24 as a current intermittent means are connected in parallel to the conventional example shown in FIG. Although the number of choppers is 1/2 that of the circuit, it is possible to absorb the same regenerative power. Note that since the circuit for controlling this regenerative power absorption device is the same as that already described in FIG. 5, illustration and operation description of this control circuit will be omitted.

As is clear by comparing Figures 5 and 8.

For 1500 volt circuits, GTO has a withstand voltage of 4500 volts.
By using a thyristor, the number of parallel chips can be halved, but doing so causes various problems as described below. Namely.

b) Since the number of choppers in parallel is reduced, the effect of suppressing harmonic current by operating these choppers with shifted operating phases is reduced. In electric railway systems, if the thickness of the harmonic current flowing through the tracks is not suppressed, there is a risk that signal control equipment and level crossing control equipment will malfunction, and there is a risk of a major accident.However, the harmonic current increases. There are drawbacks to doing so.

In the current GTO thyristors, if the current capacity is the same, the same snubber capacitor 154 is used regardless of whether the withstand voltage is 2,500 volts or the withstand voltage is 4,500 volts1. Assuming that the capacitance is the C1 circuit voltage and f is the operating frequency of the chopper, the loss P generated in the snubber resistor 153 is (1
) is shown by the formula.

P=IC・■2・f・・・・・・・・・・・・・・・
・・・・・・・・・・・・Song... (1) As is clear from this equation (11), even if the chopper frequency f and the snubber capacitor capacity C are the same.

As the circuit voltage doubles from 750 volts to 1500 volts, the snubber resistance loss P quadruples.

Since the number of parallel devices is halved, the snubber resistance loss P in the entire device ends up being doubled, resulting in a decrease in device efficiency and the need to increase the size of the device to dissipate this loss, which increases cost. .

c) In order to suppress the increase in harmonic current despite the decrease in the number of choppers (measures mentioned in item (a) above).

The chopper frequency f must be doubled.

This K increases the switching loss of the ω°C thyristor 151. Furthermore, due to the increase in the chopper frequency f, the snubber resistance loss P further increases, further reducing the efficiency of the device, and the device must be enlarged to deal with the generated loss.

It has the disadvantage of increasing costs.

2) Currently, GTO thyristors with a withstand voltage of 4,500 volts are much more expensive than those with a withstand voltage of 2,500 volts, so they have the disadvantage of increasing the cost of the device.

[Purpose of the invention]

This invention is designed to inexpensively absorb surplus regenerative power generated by regenerative operation in electric railway systems where the voltage of the power supply line is relatively high, without increasing equipment loss or harmonic current. The purpose of the present invention is to provide a regenerative power absorption device that can perform the following tasks.

° [Summary of the Invention] This invention provides that if the number of operating current intermittent means constituting a regenerative power absorption device is increased and the operating phases of these current intermittent means are shifted from each other, the current This method focuses on the fact that harmonic currents can be suppressed without increasing the operating frequency of the intermittent means, and if the voltage of one circuit is high, multiple capacitors connected in series can be connected between the power supply line and the ground. A plurality of series circuits consisting of a current intermittent means composed of a switching element with a low withstand voltage characteristic and a resistor are connected in parallel to each of the above-mentioned capacitors. By operating them at a relatively low frequency and with an equal phase difference, switching loss and snubber resistance loss are suppressed to low levels, making the device more compact, and reducing harmonics that can cause malfunctions in various control devices. [Embodiment of the Invention] Figure 1 is a main circuit connection diagram showing an embodiment of the present invention, and the details of the present invention will be explained below using this Figure. explain. Note that the voltage of the feeder line in FIG. 1 is a high voltage, for example 1
500 volts, whereas the GTO thyristors as switching elements used in the four sets of chips 41 to 44 as current intermittent means have a withstand voltage of 2500 volts (
This is used for a circuit voltage of 750 volts).

In FIG. 1, the line voltage is divided into two by connecting a series circuit of an upper stage capacitor 30A and a lower stage capacitor 30B as an input capacitor between the 1500 volt power supply line and the ground. j 4 sets of current intermittent means 41 to 44 K each have a load resistance of 3
1 to 34 are connected in series, and two of the four series circuits configured in this way are connected to the upper stage capacitor 3.
0A in parallel, and the remaining two sets are lower stage capacitors 30
B is connected in parallel. In addition, these choppers 41~
Since the circuit for controlling 44 is the same as the conventional circuit shown in FIG. 5, illustration and operation description of the control circuit will be omitted.

The four sets of choppers 41 to 44 shown in FIG. 1 are operated as follows. In other words, the two sets of capacitors 41 and 42 connected in parallel with the upper stage capacitor 30AK are in two-phase operation, that is, 18
It operates with a phase difference of 0 degrees. Also, lower stage capacitor 30B
The two sets of choppers 43 and 44 connected to the
It operates with a phase difference of degrees.

At this time, K is set so that there is a phase difference of 90 degrees between the upper chopper 41 and the lower chopper collar 43. In this way, the four choppers 41 to 44 operate with a mutually equal phase difference of 90 degrees.

FIG. 2 is an operational waveform diagram illustrating an example of the operation of the embodiment circuit shown in FIG. 1, and shows the case where the above operation is performed. In other words, FIG. 2(a) shows the current I41 flowing through the chopper 41.
Figure 2 (b) shows the change in the current I flowing through the chopper 42.
Figure 2 (C) shows the change in the combined current I41 + I42 flowing to the upper chopper, Figure 2 (E) shows the voltage Vm of the upper stage capacitor 30A, and Figure 2 (E) shows the change in the combined current I41 + I42 flowing to the upper chopper.
2(g) shows the change in the current I44 flowing through the chopper 44, and FIG. 2(g) shows the change in the combined current I43+I44 flowing through the lower chopper.
FIG. 2(G) shows the change in the voltage VB of the lower stage capacitor 30B, and FIG. 2(S) shows the change in the input voltage (that is, the voltage of the upper stage capacitor 30A and the lower stage capacitor 30B) Vc.

As is clear from Fig. 2, the voltage ripple of the 30 upper stage capacitors and the lower stage capacitor 30B is twice the frequency of each chopper, but the voltage ripple frequency of the input voltage Vc is four times the chopper frequency. At the same time, the voltage ripple value becomes small (see the solid line in Figure 2).The broken line in Figure 2 (see the solid line in Figure 2) indicates the voltage ripple when the chopper is operated in two phases using the conventional circuit shown in Figure 8. This is a change in input voltage, and as is clear from the comparison between the solid line and the broken line in this figure, the switching element is 4500 mm.
Compared to two sets of choppers using volt-resistant GTO thyristors, the voltage ripple frequency is twice as high and the voltage ripple is 1/4.

In the embodiment circuit shown in FIG.
-44 can also be operated as in the second example of operation described below. In other words, the chopper 41 and chip 42 connected in parallel to the upper capacitor 30A are operated with a phase difference of 90 degrees, and the chopper 43 and chopper 44 connected in parallel to the lower capacitor 30B are operated with a phase difference of 90 degrees. At the same time, the chopper 41 on the upper stage and the chopper 43 on the lower stage are operated with a phase difference of 180 degrees, so that the four sets of choppers 41 to 44 have an equal 90
It will operate with a degree of phase difference.

FIG. 3 is an operation waveform diagram showing a second operation example of the embodiment circuit shown in FIG. and I42
Figure 3 (c) shows the change in the composite current I4 of the upper chopper.
1 + engineering 42 (see Figure 3) is the upper stage capacitor 30
Figures 3(e) and 3(f) show the changes in the currents I43 and I44 flowing through the choppers 43 and 44 on the lower stage, and the example in Figure 3 shows the combined current I43+1.
44, FIG. 3(1) shows the change in the voltage VB of the lower stage capacitor 30B, and FIG. 3(S) shows the change in the input voltage Vc.

In the second operation example shown in FIG.
Since the voltage ripples of 0A and lower stage capacitor 30B are larger than in the case of the operation example shown in Fig. 2, it is necessary to increase the capacitor capacity, but the input voltage Vc is lower than the case of the operation example shown in Fig. 2. This is the same as in the case of , and therefore harmonic currents can be similarly suppressed.

The above explanation is for the case where four sets of choppers are used,
Of course, the present invention can be applied even when N sets of capacitors are divided into upper and lower sections and operated with a phase difference between them, or when a large number of input capacitors are connected in series to divide the voltage. It is.

Furthermore, it goes without saying that the purpose of the present invention will not be diminished even if other semiconductor elements are used as switching elements.

〔Effect of the invention〕

According to this invention, by connecting a series connection circuit of a plurality of capacitors between a high-voltage power supply line and the ground, the line voltage is divided by the capacitor, and the current generated by switching elements with low withstand voltage characteristics is divided. A regenerative power absorption device is constructed by connecting a plurality of series circuits of an interrupting means and a resistor in parallel to each of the above-mentioned capacitors. When there is a surplus of regenerative power due to regenerative operation of a DC electric vehicle, if these current intermittent means are operated with the same phase difference, even if the operating frequency is low, the regenerative power absorption device Since the ripple frequency of the input voltage becomes higher and the voltage ripple becomes smaller, harmonic currents are also suppressed, and it is possible to avoid the risk of various control devices of the electric railway system malfunctioning due to harmonic currents.

Furthermore, the operating frequency of the current intermittent means is low.

Switching loss and snubber loss of switching elements can also be suppressed to a low level, contributing to improved efficiency, miniaturization, and cost reduction of devices. Furthermore, since low breakdown voltage switching elements can be used, this also has the effect of further reducing the cost of the device.

[Brief explanation of the drawing]

FIG. 1 is a main circuit connection diagram of the present invention, FIG. 2 is an operation waveform diagram showing an example of the operation of the embodiment circuit shown in FIG. 1, and FIG. FIG. 2 is an operation waveform diagram showing the second operation example. FIG. 4 is an explanatory diagram showing a regenerative braking system for a DC electric vehicle, and FIG. 5 is a circuit diagram showing a conventional example of a regenerative force absorption device used in a low voltage circuit. FIG. 6 is an operation waveform diagram showing the operation of each part of the conventional circuit shown in FIG. 5, FIG. 7 is a circuit diagram showing an example of a switching element constituting a chopper, and FIG. FIG. 2 is a main circuit connection diagram showing a conventional example of a regenerative power absorption device used. 2... Substation, 3... Regenerative power absorption device, 4...
Power supply line, 5, 6...DC electric car, 5M, 5M・
...DC motor. 5P, 6P... Pantograph, 58.58...
・Switch, 7... Phase shifter, 8... Voltage regulator,
9.20...Input capacitor. 10... Voltage setting device, 11 to 14, 21, 22.31
~34...Load resistance. 15-1B, 23, 24. 41-44... Chopper as current intermittent means, 30A... Upper stage capacitor, 3
0B... lower stage capacitor, 151... GTO thyristor as a switching element, 152... snubber diode, 153... snubber resistor, 154... snubber capacitor. Yamaguchi, a patent attorney, p6: ゛ Kuji Figure 1 Figure 2 T: Kaimei Figure 3 Figure 5 Figure 6

Claims (1)

[Claims] 1) A capacitor is connected between the power supply line that supplies DC power to the electric car and the earth, and multiple sets of series circuits each including a current interrupting means and a resistor are connected in parallel to this capacitor, and each of the current intermittent In the regenerative power absorption device which absorbs surplus power into the resistor when the electric vehicle performs regenerative operation by operating the means with operating phases shifted from each other by a predetermined value, the power supply line and the ground are connected to each other. A plurality of capacitors connected in series are connected between the two capacitors, and the necessary number of series circuits each equipped with a current interrupting means having mutually equal operating phase differences are connected in parallel for each capacitor. A regenerative power absorption device characterized by: