JPH0543531B2 - - Google Patents

Description

[Detailed description of the invention] [Technical field to which the invention pertains] This invention enables stable operation of a regenerative braking system by quickly absorbing surplus regenerative power generated when a DC electric vehicle performs regenerative operation. The present invention relates to a method of controlling a regenerative power absorption device.

[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/variable frequency AC power to rotate the AC motor. Therefore, when decelerating this DC electric car or running on a downhill board, regenerative braking operation that converts the energy held by the DC electric car into electrical energy and returns it to the power source is easy. It became.

FIG. 3 is an explanatory diagram showing a regenerative braking system for a DC electric vehicle. In FIG. 3, 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 power from pantographs 5P, 6P, and switch 5S, 6P.
After rotating the DC motors 5M and 6M via 6S, the electric car is driven by discharging water to the ground via wheels and rails. However, illustration of a chopper for controlling the DC motors 5M, 6M is omitted.

In FIG. 3, assuming that one DC electric car 5 is in power running and the other DC electric car 6 is in regenerative operation, the electric car ₅ in power running is Since power running will be performed using the sum of the current and the current _I6 regenerated from the electric car 6, the power output by the substation 2 should be the value obtained by subtracting the power regenerated from the electric car 6. Therefore, it is possible to save energy.

However, as described above, if the electric power required by the electric car 5 in power running decreases or the electric power regenerated from the electric car 6 in regenerative operation increases, the output from the substation 2 will be reduced accordingly. The current I ₂ decreases and finally reaches zero. Even if the output of the substation 2 becomes zero, if the power regenerated from the electric car 6 is not consumed by the running electric car 5, this surplus regenerated power will cause problems such as increasing the voltage of the power supply line 4. In order to prevent this, a regenerative power absorption device 3 is connected to the power supply line 4, and if there is a surplus of regenerative power, it is absorbed into the regenerative power absorption device 3. That is, in FIG. 3, the output current _I2 from the substation 2 is zero, and the DC electric car 5 is powered by the current _I6 regenerated from the DC electric car 6, which is then regenerated. By absorbing the surplus current _I3 into the regenerative power absorption device 3, the illustrated regenerative braking system can continue to operate while being balanced.

FIG. 4 is a circuit diagram showing a conventional example of a regenerative power absorption device, in which an input capacitor 31 is connected between a power supply line 4 and the ground, a load resistor 32 and a chopper 33 as a current continuation means. The regenerative power absorbing device 3 is configured by connecting a series circuit of the input capacitor 31 in parallel to the input capacitor 31. Note that the series circuit of the load resistor 32 and the chopper 33 is designed to increase the capacity of the regenerative power absorption device.
Multiple sets are connected in parallel to the input capacitor 31, and in order to further suppress harmonics during operation of the regenerative power absorption device, _a so-called multi-phase operation method is adopted in which the plurality of choppers are operated with phase differences. However, in the present invention, in order to simplify the illustration, the above-mentioned series circuits are combined into one set.

When there is a surplus in the regenerative power, regenerative current I ₃ flows from the power supply line 4 to the regenerative power absorption device 3 and increases the voltage V _c of the input capacitor 31 . The deviation between the voltage V _s set by the voltage setting device 36 and this capacitor voltage V _c is input to the voltage regulator 34, and the voltage regulator 34 sends a control signal V ₃₄ to make the input deviation zero to a phase shifter. Since the phase shifter 35 controls the chopper 33, if the voltage V _c of _the input capacitor 31 rises, the chopper 33
The conduction rate of is adjusted to an appropriate value, and the intermittent current that flows accordingly is consumed by the load resistor 32.

Figure 5 shows the surplus regenerative power that changes gradually.
These are waveform diagrams showing the operation when absorbing with the conventional example circuit shown in the figure, in which _FIG . FIG. 5C shows the change in the voltage V _c and the change in the output V ₃₄ of the voltage regulator 34, respectively. As is clear from this graph, as the current _I3 flows into the regenerative power absorption device 3, the input capacitor voltage _Vc increases, and when the value exceeds the set voltage _Vs , the voltage regulator 34 is activated. As a result, the input capacitor voltage V _c
The maximum value of ΔV is higher than the set voltage _Vs , but since the voltage regulator 34 can follow changes in current _I3 , that is, changes in voltage _Vc , the value of ΔV due to voltage overshoot is small. Therefore, the regenerative power absorption device 3 effectively fulfills its responsibility.

However, in the regenerative braking system for a DC electric car shown in FIG. Although the current I ₃ flowing from the car 6 to the regenerative power absorption device 3 is zero, when the DC electric car 5 that is in power running in this state is notched off and starts coasting, the electric current I 3 flows from the DC electric car 6 to the electric car 5. All the electric power that has been regenerated toward the regenerated power absorption device 3 will be transferred to the regenerated power absorption device 3. That is, the current _I3 flowing into the regenerative power absorption device 3 rises rapidly from zero.

FIG. 6 is a waveform diagram showing the operation when the conventional circuit shown in FIG. 4 attempts to absorb rapidly changing surplus regenerative power, and FIG. The change in current I ₃ is expressed as
Figure b shows the change in the voltage V _c of the input capacitor 31,
FIG. 6C shows changes in the output V ₃₄ of the voltage regulator 34, respectively.

As is clear from FIG. 6, when the current _I3 flowing into the regenerative power absorption device 3 suddenly rises due to the above-mentioned reason, that is, the electric vehicle is notched off during power running, the voltage V of the input capacitor 31 increases. _c also rises rapidly, so that when the voltage regulator 34 starts operating, its value is equal to the set voltage V _s
The value is much higher than that of

If the resistance of the power supply line 4 between the DC electric car 6 and the regenerative power absorption device 3 during regenerative operation is R, then
Since the regenerative current is I ₃ and the voltage of the input capacitor 3, that is, the voltage of the regenerative power absorption device 3 is V _c , using these, the voltage of the DC electric car 6 during regenerative operation
V _M is expressed by the following equation (1).

V _M = V _c + R・I ₃ ... (1) That is, the voltage V _M of the electric vehicle 6 during regenerative operation increases as the voltage V _c of the regenerative power absorption device 3 increases, and this V _M is determined in advance. When the specified value V _F is exceeded, this DC electric vehicle 6 automatically stops its regenerative operation. This is called regeneration lapse, but if regeneration lapses while driving downhill with regenerative operation, the speed will increase and is dangerous. This results in the inability to stop at a predetermined position.

Due to the above-mentioned phenomenon, the voltage of the electric car during regenerative operation increases and the regeneration becomes invalid, which is thought to occur frequently, and this has a major drawback in that the electric car cannot be stably regeneratively braked.

[Purpose of the invention]

This invention suppresses a sudden rise in the voltage of the regenerative power absorption device by responding sufficiently quickly to regenerative current that flows in at a sudden rise, thereby preventing an electric vehicle in regenerative operation from reaching regenerative failure. The purpose of the present invention is to provide a method for controlling a regenerative power absorption device.

[Key points of the invention]

In this invention, the voltage control system of the regenerative power absorption device is unable to follow the regenerative current that flows in at a sudden rise and charges the input capacitor that constitutes the regenerative power absorption device, causing its voltage to rise rapidly. Because this is the cause, when the input capacitor voltage exceeds the abnormal voltage set value that is set above the set voltage at which this voltage control system starts operating, the current intermittent means that constitutes the regenerative power absorption device is activated. This is intended to immediately bring the system into full conduction and rapidly lower the input capacitor voltage, thereby preventing the electric vehicle during regenerative operation from entering a regenerative failure state.

[Embodiments of the invention]

FIG. 1 is a circuit diagram showing an embodiment of the present invention,
Based on this Figure 1, the content of this project will be described below.

In Fig. 1, from the feed line numbered 4, I ₃
The regenerative current flows into the regenerative power absorption device, which consists of an input capacitor 31 connected between the feed line 4 and the ground, and a load resistor 32 connected in parallel to the input capacitor 31. and a chopper 33 as a current intermittent means, a voltage regulator 34, a phase shifter 35, a voltage setting device 36, a comparator 41, an abnormal voltage setting device 42, and an OR element 43 for controlling the chopper 33. It is made up of.

When the regenerative current I ₃ flows through the feed line 4,
Since the input capacitor 31 is charged by this regenerative current, its voltage V _c rises gradually or rapidly in accordance with the rate of change of the regenerative current I ₃ . This voltage V _c is a predetermined value determined by the voltage setting device 36
When the voltage exceeds V _s1 , the voltage regulator 34 outputs a control signal that makes the deviation between the input voltage V _c and voltage V _s1 zero.
V ₃₄ is output to the phase shifter 35. The phase shifter 35 applies an on/off signal B corresponding to the input signal V ₃₄ to the chopper 33 via the OR element 43, and turns on/off the switch elements constituting the chopper 33.
Since regenerative power is consumed by the load resistor 32 by turning it off, the first step is to prevent the voltage V _c of the input capacitor 31 from becoming excessive and to suppress it to a predetermined value V _s1 by the voltage setter 36. The circuit shown in FIG. 4 is the same as the case of the conventional circuit described above.

When the rise of the regenerative current I ₃ is sudden, the sudden rise in the capacitor voltage V _c cannot be suppressed by the above-mentioned control operation alone; however, in the present invention, this capacitor voltage V _c is also applied to the comparator 41. When this capacitor voltage V _c exceeds the set value V _s2 of the abnormal voltage setting device 42, which is set higher than the predetermined value V _s1 set by the voltage setting device 36, the comparator 41 operates at that moment, and A
Since a signal that makes the chopper 33 fully conductive is given from the comparator 41 to the chopper 33 via the OR element 43, surplus regenerative power flowing into the regenerative power absorption device is quickly absorbed by this fully conductive signal, and the input capacitor 31 voltage V _c
can be quickly lowered to the predetermined value V _s1 .

FIG. 2 is an operation waveform diagram showing the operation of each part of the embodiment circuit shown in FIG. 1, _{and FIG} .
2B shows the change in the voltage V _c of the input capacitor 31, FIG. 2C shows the change in the output V ₃₄ of the voltage regulator 34, and FIG. 2D shows the change in the output A of the comparator 41. E represents the change in the output B of the phase shifter 35, and FIG. 2H represents the change in the output C of the OR element 43, respectively.

As is clear from Fig. 2, the current I ₆ (indicated by the broken line in Fig. 2 A) that was flowing into the electric vehicle during power running is converted into regenerative current I ₃ at the moment the power running vehicle is notched off. Since it flows into the regenerative power absorption device, its rise is extremely rapid. Therefore, the voltage V _c of the input capacitor 31 also increases rapidly, exceeding the predetermined value V _s1 in a very short time and reaching the abnormal voltage set value V _s2 (see FIG. 2B).
At this time, the output V ₃₄ of the voltage regulator 34 has not yet risen sufficiently, and therefore the output B of the phase shifter 35 is
The ratio of the on time to the off time of the signal is also small (see Figure 2 E), and the regenerative power absorption device cannot fully demonstrate its ability if it continues as it is, but when the capacitor voltage V _c reaches V _s2 By doing so, the comparator 41 operates immediately. Therefore, while the comparator 41 is operating, a signal to be fully conductive is given to the chopper 33 via the OR element 43 (see FIG. 2), so regenerative power is consumed in the load resistor 32 and the capacitor Since the voltage V _c can be quickly lowered to the predetermined value V _s1 , it is possible to prevent regeneration failure of the electric vehicle during regenerative operation.

When the overvoltage setting value set on the regenerative electric vehicle side, that is, the voltage at which regeneration failure occurs, is V _F , if the abnormal voltage setting value V _s2 is determined to match the conditions shown in equation (2) below, then There is no possibility that regeneration will fail on the electric vehicle side. Here, R _nax is the feed line 4
I _nax is the maximum value of the regenerative current.

V _s2 ≦V _F −R _nax・I _nax ...(2) Note that as the comparator 41 in the above description, it is also possible to use a comparator with hysteresis characteristics in which the operating level and the recovery level are different, and this comparator It goes without saying that the gist of the present invention will not be impaired even if a filter or a timer is provided after the chopper 41 so that the total conduction period of the chopper 33 can be adjusted. It goes without saying that the gist of the present invention can also be applied to the multi-phase operation using the multiple chopper described above.

[Effects of the Invention] According to the present invention, a regenerative power absorption device constituted by a series circuit of an input capacitor, a resistor connected in parallel to the input capacitor, and a current interrupting means is connected between the power supply line and the ground. When the regenerative current flows into the input capacitor and increases its voltage, when the capacitor voltage reaches a predetermined value, the voltage control system turns on the current intermittent means.
It operates off and absorbs regenerated power,
When the capacitor voltage exceeds the predetermined value and reaches the abnormal voltage setting value, the current interrupting means is immediately made fully conductive by the function of the comparator, so that the current flows into the regenerative power absorption device. Even if the regenerative current increases extremely rapidly, the incoming regenerative power can be quickly consumed, which prevents the voltage of the input capacitor from increasing rapidly, and the electric vehicle during regenerative operation can It is possible to prevent the brake system from becoming inactive, thereby achieving the effect of realizing a stable regenerative braking system.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing an embodiment of the present invention,
FIG. 2 is an operation waveform diagram showing the operation of each part of the embodiment circuit shown in FIG. 1. Fig. 3 is an explanatory diagram showing a regenerative braking system for a DC electric vehicle, Fig. 4 is a circuit diagram showing a conventional example of a regenerative power absorption device, and Fig. 5 is an explanatory diagram showing a regenerative braking system for a DC electric vehicle. FIG. 6 is a waveform diagram showing the operation when the conventional circuit shown in FIG. 4 absorbs the surplus regenerative power, and FIG. 6 shows the operation when the conventional circuit shown in FIG. FIG. 2... substation, 3... regenerative power absorption device, 4...
...Feeding line, 5, 6...DC electric car, 5M, 6M
...DC motor, 5P, 6P...pantograph,
5S, 6S...Switch, 31...Input capacitor, 32...Load resistor, 33...Chopper as current intermittent means, 34...Voltage regulator, 35...
Phase shifter, 36... Voltage setting device, 41... Comparator, 42... Abnormal voltage setting device, 43... OR element.

Claims (1)

[Claims] 1. Connect a capacitor between the power supply line that supplies DC power to the electric vehicle and the ground, connect the required number of series circuits of current interrupting means and resistors in parallel to this capacitor, and connect both ends of this capacitor. In the method for controlling a regenerative power absorption device, in which surplus power during regenerative operation of the electric vehicle is absorbed into the resistor by operating the current intermittent means when the voltage exceeds a predetermined value, both ends of the capacitor are operated. A method for controlling a regenerative power absorption device, characterized in that when the voltage exceeds the predetermined value and becomes equal to or higher than the predetermined set value, all of the current intermittent means are operated in full conduction.