CN103715656B - The over-pressure safety device of chopper, chopper and electric locomotive - Google Patents
The over-pressure safety device of chopper, chopper and electric locomotive Download PDFInfo
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- CN103715656B CN103715656B CN201210370346.1A CN201210370346A CN103715656B CN 103715656 B CN103715656 B CN 103715656B CN 201210370346 A CN201210370346 A CN 201210370346A CN 103715656 B CN103715656 B CN 103715656B
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Abstract
The present invention provides the over-pressure safety device of a kind of chopper, chopper and electric locomotive; this over-pressure safety device includes voltage detection unit, the first voltage comparison unit, very first time acquiring unit, energy absorption unit and fuse; wherein, voltage detection unit is arranged in the outfan circuit of buck chopper；First voltage comparison unit is connected with voltage detection unit；Very first time acquiring unit and the first voltage comparison unit are connected；After energy absorption unit detects unit for the output end voltage being arranged on buck chopper, and it is connected with very first time acquiring unit；Fuse is for being series in the input circuit of chopper.This over-pressure safety device; the components and parts connected in the output overvoltage infringement following stage circuit of chopper can be prevented; under playing the premise that relevant device is protected; the switching frequency of chopper can be reduced; and then; improve the service life of chopper, improve and apply the stability that the system of this chopper is run.
Description
Technical Field
The invention relates to an electrical control technology, in particular to an overvoltage protection device of a chopper, the chopper and an electric locomotive.
Background
With the increasing maturity of power electronic circuits and alternating current speed regulation technologies, alternating current transmission systems are more and more widely applied to the field of electric locomotives, the alternating current transmission systems of the electric locomotives can be divided into traction electric transmission systems and auxiliary variable flow systems, the existing auxiliary variable flow systems have various design structures, and an intermediate loop power taking mode is a mode which is more widely applied.
The auxiliary converter system of this mode is usually provided with a step-down chopper, and the high-voltage direct current output from the intermediate circuit of the traction electric transmission system is subjected to step-down processing by the step-down chopper to output a voltage with a lower voltage level, and then the voltage is output to the three-phase inverter, and the voltage is further modulated by the three-phase inverter to generate a required voltage, so as to be supplied to corresponding equipment in the electric locomotive as a working voltage source.
The auxiliary converter system in the mode does not need to be provided with a rectifying module, so that the cost is reduced, but the mode introduces high voltage of an intermediate loop of the traction electric transmission system, so that higher requirements are put forward on the voltage withstanding property of electric elements in the auxiliary converter system, and an overvoltage suppression protection link is required to be arranged for preventing the high voltage from being transmitted into a rear-stage circuit and damaging the rear-stage circuit due to the fault of a step-down chopper or the fluctuation of the grid voltage.
In the prior art, the overvoltage suppression protection method mainly includes detecting an output voltage of a step-down chopper, and blocking a trigger pulse of the step-down chopper when the output voltage exceeds a set voltage threshold, so that the step-down chopper is controlled to stop working, and the purpose of overvoltage suppression protection is achieved.
During the working process of the traction electric transmission system, due to instantaneous fluctuation of the grid voltage or other reasons, the voltage output by an intermediate loop of the traction electric transmission system has large fluctuation in a short time, so that the output voltage of the step-down chopper has large fluctuation in a short time.
If the time of the voltage fluctuation of the power grid is short and the overvoltage energy is small, such as several nanoseconds, the work of the step-down chopper is not required to be stopped at the moment because the time is short and the overvoltage energy is small; however, under the existing overvoltage suppression protection method, once the grid voltage fluctuates instantaneously, the step-down chopper is controlled to stop working, so that frequent switching of the step-down chopper is caused, the stable operation of the auxiliary converter system is not facilitated, and the service life of electrical elements in the system is influenced.
Disclosure of Invention
The first aspect of the invention is to provide an overvoltage protection device for a chopper, so as to prolong the service life of the chopper and improve the stability of the operation of a system using the chopper.
In order to achieve the above object, the present invention provides an overvoltage protection device for a chopper, comprising:
the voltage detection unit is arranged at the output end of the chopper to collect the output voltage of the chopper;
the first voltage comparison unit is used for generating a first overvoltage pulse signal when the output voltage is judged to be larger than a first voltage control threshold value;
the first time acquisition unit is connected with the voltage detection unit and used for acquiring the duration of the first overvoltage pulse signal and generating a first overvoltage protection signal when the duration is judged to be larger than a first preset time;
and the electric energy absorption unit is arranged at the output end of the chopper, is connected with the first time acquisition unit and is used for absorbing the electric energy at the output end of the chopper when receiving the first overvoltage protection signal so as to reduce the output voltage at the output end of the chopper.
And the fuse is used for being connected in series in the input end line of the chopper, and is fused to disconnect the input end line of the chopper when the voltage at the output end of the chopper is greater than the output voltage threshold for a set time.
In a second aspect of the invention, the chopper is provided with the overvoltage protection device provided by the invention, the voltage detection unit and the electric energy absorption unit in the overvoltage protection device are respectively arranged in an output end line of the chopper, and the fuse in the overvoltage protection device is connected in series in the input end line of the chopper.
The invention provides an electric locomotive, which comprises a traction electric transmission system and an auxiliary conversion system, wherein the auxiliary conversion system comprises a three-phase inverter, and the electric locomotive is characterized in that the auxiliary conversion system is also provided with a chopper provided by the invention, the input end of the chopper is connected with a middle output loop of the traction electric transmission system, and the output end of the chopper is connected with the three-phase inverter.
The overvoltage protection device of the chopper provided by the invention does not control the step-down chopper to stop working once the output voltage of the chopper exceeds the voltage during normal working, but only absorbs the electric energy at the output end of the chopper through the electric energy absorption unit under the condition that the output voltage exceeds the voltage during normal working due to larger fluctuation of the voltage at the input end of the chopper or other reasons and lasts for a certain time, thereby reducing the output voltage of the chopper to prevent the damage of the overhigh output voltage to corresponding equipment connected with the rear end of the chopper, and when the electric energy absorption unit can not pull down the voltage at the output end of the chopper after being started for a certain time, the input end line of the chopper is disconnected through the fuse to stop working of the chopper, prevent the high voltage at the input end of the chopper from being transmitted to the corresponding equipment at the rear end, and protect the corresponding equipment in time, the chopper can reduce the frequency of starting the chopper on the premise of protecting corresponding equipment, thereby prolonging the service life of the chopper and improving the stability of the system using the chopper.
According to the auxiliary converter system in the electric locomotive, the chopper provided by the embodiment of the invention is arranged, so that the condition that components in a post-stage circuit are damaged due to overhigh output voltage of the chopper can be prevented, and the frequency for starting the chopper can be reduced on the premise of protecting corresponding equipment, so that the service life of the chopper is prolonged, the running stability of the auxiliary converter system is improved, and the running stability of the electric locomotive is further improved.
Drawings
FIG. 1 is a schematic structural diagram of an overvoltage protection device for a chopper according to an embodiment of the present invention;
FIG. 2 is a schematic structural diagram of an overvoltage protection device for a chopper according to another embodiment of the present invention;
fig. 3 is a schematic structural diagram of an overvoltage protection device for a chopper according to another embodiment of the present invention.
Detailed Description
A chopper is a device that converts a fixed dc voltage into a variable dc voltage, and is generally a circuit including elements such as a controllable rectifier element, an inductor, a capacitor, and a resistor. The chopper can be applied to various power systems, and the output voltage obtained by converting the voltage by the chopper can be used as a working voltage source of corresponding equipment in the power systems.
The embodiment of the invention provides an overvoltage protection device of a chopper, which can be used for monitoring the output voltage of the chopper, and has the function of inhibiting the output voltage when the output voltage exceeds a set range so as to prevent the over-high output voltage from damaging equipment connected to the rear end.
Fig. 1 is a schematic structural diagram of an overvoltage protection device of a chopper according to an embodiment of the present invention, and as shown in fig. 1, the overvoltage protection device includes a voltage detection unit 10, a first voltage comparison unit 11, a first time acquisition unit 12, an electric energy absorption unit 13, and a fuse 14.
And the voltage detection unit 10 is used for being arranged at the output end of the chopper 50 so as to acquire the output voltage of the chopper 50.
The voltage detection unit can adopt a high-precision voltage sensor and is arranged at the output end of the chopper so as to acquire the output voltage of the chopper according to the acquisition period.
And the first voltage comparison unit 11 is connected with the voltage detection unit 10 and is used for generating a first overvoltage pulse signal when the output voltage is judged to be greater than a first voltage control threshold value.
And the first time acquisition unit 12 is connected with the first voltage comparison unit 11 and is used for acquiring the duration of the first overvoltage pulse signal and generating a first overvoltage protection signal when the duration is judged to be greater than a first preset time.
When the chopper normally works, the output voltage at the output end of the chopper is within a certain range, when the voltage at the input end of the chopper fluctuates greatly or due to other reasons, the output voltage exceeds the certain range of the voltage during the normal work, if the duration of the output voltage is short, for example, several nanoseconds or several milliseconds, the corresponding equipment connected to the rear end of the chopper can not be damaged normally, and the corresponding equipment can bear the fluctuation, but if the duration of the output voltage is long, the corresponding equipment can be damaged.
In this embodiment, the first voltage control threshold and the first preset time are referred to when the output voltage of the chopper is once greater than a certain voltage and the duration time exceeds a certain time, which may damage corresponding devices, the first voltage control threshold may be equal to or slightly less than the output voltage in this case, and the first preset time may be equal to or slightly less than the duration time in this case.
The first voltage comparison unit can be realized by a voltage comparator or a corresponding hardware circuit, the first voltage comparison unit can compare the output voltage acquired by the voltage detection unit with a first voltage threshold, and when the output voltage is judged to be greater than the first voltage control threshold, a first overvoltage pulse signal is generated.
The first time obtaining unit can be an industrial computer, a single chip microcomputer, a programmable processor or other processor.
The first time obtaining unit may obtain a duration of the received first overvoltage pulse signal according to the received first overvoltage pulse signal, and the duration may be obtained by calculating a pulse width of the pulse signal, because if the output voltage is continuously greater than the first voltage control threshold, the pulse width of the first overvoltage pulse signal generated by the first voltage comparing unit is also continuously greater, and the pulse width is proportional to the duration of the output voltage greater than the first voltage control threshold.
For example, in the state that the output voltage is smaller than the first voltage control threshold, the output of the first voltage comparison unit is at a low level, when the output voltage is greater than the first voltage control threshold, the output of the first voltage comparison unit jumps to a high level, i.e., a pulse signal, i.e., the first overvoltage pulse signal in this embodiment, is generated, and if the output voltage is continuously greater than the first voltage control threshold, the first voltage comparison unit continuously outputs a high level, i.e., the output time (i.e., the pulse width) of the high level is the duration of the output voltage greater than the first voltage control threshold.
And the electric energy absorption unit 13 is arranged at the output end of the chopper 50, is connected with the first time acquisition unit 12, and is used for absorbing the electric energy at the output end of the chopper when receiving the first overvoltage protection signal so as to reduce the output voltage at the output end of the chopper.
The electric energy absorption unit can be realized by adopting a corresponding hardware circuit, the electric energy absorption unit is used for absorbing the electric energy at the output end of the chopper, when the electric energy absorption unit receives a first overvoltage protection signal, namely when the duration that the output voltage of the chopper is greater than a first voltage control threshold value exceeds a first preset time, the electric energy at the output end of the chopper begins to be absorbed, and after the electric energy generated by overvoltage is absorbed by the electric energy absorption unit, the effect of restraining the output voltage of the chopper can be achieved, so that the output voltage at the output end of the chopper is reduced, and further, the damage to equipment connected to the rear end of the chopper due to overhigh output voltage is prevented.
And the fuse 14 is used for being connected in series in the input end line of the chopper 50, and when the voltage at the output end of the chopper 50 is greater than the output voltage threshold value for a set time, the fuse 14 is fused to disconnect the input end line of the chopper 50.
The output voltage threshold is referred to the output voltage of the chopper during normal operation, and may be equal to or slightly greater than the output voltage during normal operation, and the set time is referred to the duration that the duration when the output voltage of the chopper is greater than the output voltage threshold does not cause damage to the corresponding device, and may be equal to or slightly less than the duration in this case.
The output voltage threshold and the setting time are related to relevant parameters of the electric energy absorption unit and parameters of the fuse, and the electric energy absorption unit and the fuse with proper parameters can be selected according to requirements. The fuse is used for being connected in series in an input end line of the chopper, because the absorption capacity of the electric energy absorption unit is limited, when the electric energy absorption unit is started for a certain time (namely set time), namely the absorption capacity of the electric energy absorption unit is fully exerted, and the voltage at the output end of the chopper is still higher, namely still higher than the output voltage threshold value, as the input voltage of the chopper is higher than the voltage in a normal working state, the current in the input end line is rapidly increased, the fuse is fused, the input end line of the chopper is disconnected, the chopper stops working, the high voltage at the input end of the chopper can be prevented from being transmitted to corresponding equipment at the rear end, the corresponding equipment is protected in time, and the safety of the whole circuit system is protected.
Under normal conditions, when the voltage at the input end of the chopper fluctuates to a large extent or due to other reasons, the output voltage of the chopper exceeds a certain range of the voltage during normal operation, the electric energy absorption unit can reduce the output voltage at the output end of the chopper, so that the output voltage accords with the output voltage during normal operation, and only under certain conditions, when the voltage at the output end of the chopper cannot be reduced after the electric energy absorption unit is started for a certain time, the fuse is fused to disconnect the line at the input end of the chopper, so that the chopper stops operating.
According to the technical scheme, the overvoltage protection device does not control the step-down chopper to stop working once the output voltage of the chopper exceeds the voltage during normal working, but only absorbs the electric energy at the output end of the chopper through the electric energy absorption unit under the condition that the output voltage of the chopper exceeds the voltage during normal working due to large fluctuation of the voltage at the input end of the chopper or other reasons and lasts for a certain time, so that the output voltage of the chopper is reduced, the damage to corresponding equipment connected to the rear end of the chopper due to overhigh output voltage is prevented, and when the output voltage of the chopper can not be reduced after the electric energy absorption unit is started for a certain time, the input end line of the chopper is disconnected through the fuse, so that the chopper stops working, the high voltage at the input end of the chopper is prevented from being transmitted to the corresponding equipment at the rear end, and the corresponding equipment is protected in time, the chopper can reduce the frequency of starting the chopper on the premise of protecting corresponding equipment, thereby prolonging the service life of the chopper and improving the stability of the system using the chopper.
Fig. 2 is a schematic structural diagram of an overvoltage protection device of a chopper according to another embodiment of the present invention, and further, as shown in fig. 2, the overvoltage protection device may further include a second voltage comparing unit 15 and a second time obtaining unit 16.
The second voltage comparison unit 15 is connected to the voltage detection unit 10, and configured to generate a second overvoltage pulse signal when it is determined that the output voltage is greater than a second voltage control threshold, where the second voltage control threshold is greater than the first voltage control threshold;
and the second time acquisition unit 16 is respectively connected with the second voltage comparison unit 15 and the electric energy absorption unit 13, and is used for acquiring the duration of the second overvoltage pulse signal, and generating a second overvoltage protection signal to send to the electric energy absorption unit 13 when the duration is judged to be greater than a second preset time, so that the electric energy absorption unit 13 absorbs the electric energy at the output end of the chopper 50 to reduce the output voltage at the output end of the chopper 50, and the second preset time is less than the first preset time.
The second voltage control threshold and the second preset time are based on the output voltage and the duration of the chopper when the output voltage of the chopper is greater than the voltage of the chopper during normal operation for some reason and the output voltage exceeds the first control voltage threshold and if the duration of the output voltage exceeds a certain time (the time is less than the first preset time), the corresponding equipment connected to the rear end of the chopper is damaged, the second voltage control threshold may be equal to or slightly less than the output voltage in this case and greater than the first control voltage threshold, and the second preset time may be equal to or slightly less than the duration in this case and less than the first preset time.
The second voltage comparison unit can be realized by a voltage comparator or a corresponding hardware circuit, can compare the output voltage acquired by the voltage detection unit with a second voltage threshold, and generates a second overvoltage pulse signal when the output voltage is judged to be greater than the second voltage control threshold.
The second time acquisition unit can be an industrial computer, a single chip microcomputer, a programmable processor or other processors, and the like, and can be independently arranged or can be integrated with the first time acquisition unit together.
The second time obtaining unit can obtain the duration time of the signal according to the received second overvoltage pulse signal, the duration time is compared with second preset time, and when the duration time is judged to be larger than the second preset time, a second overvoltage protection signal is generated to be sent to the electric energy absorption unit, and then the electric energy absorption unit absorbs the electric energy at the output end of the chopper so as to reduce the output voltage at the output end of the chopper.
In this embodiment, of course, after the electric energy absorption unit is started for a certain time, the voltage at the output end of the chopper is still high, that is, still greater than the output voltage threshold, and at this time, the fuse is also blown out, so as to disconnect the line at the input end of the chopper, and the chopper stops working, thereby preventing the high voltage at the input end from being transmitted to the corresponding device at the rear end, protecting the corresponding device in time, and protecting the safety of the whole circuit system.
In the embodiment, a second voltage comparison unit and a second time acquisition unit are further arranged to achieve a secondary overvoltage protection function, when the output voltage of the chopper is greater than a first voltage control threshold and the duration time is greater than a first preset time, the electric energy at the output end of the chopper can be absorbed through an electric energy absorption unit, so that the output voltage of the chopper is reduced, damage to corresponding equipment connected to the rear end of the chopper due to overhigh output voltage is prevented, and a primary overvoltage protection function is achieved; and when the output voltage of the chopper is further increased to be larger than a second voltage control threshold value and the duration time is longer than a second preset time, the electric energy at the output end of the chopper can be absorbed through the electric energy absorption unit, so that the output voltage of the chopper is reduced, the effect of secondary overvoltage protection is achieved, the output voltage of the chopper is divided into two levels, the overvoltage protection is carried out according to the conditions, and corresponding equipment can be better protected.
FIG. 3 is a schematic structural diagram of an overvoltage protection device of a chopper, according to another embodiment of the present invention, as shown in FIG. 3, in which the power absorption unit 13 includes a diode V1Thyristor V2And a reactor L1Wherein
the diode V1For connecting in parallel in the output line of the chopper 50, and the thyristor V2And a reactor L1And the diode V1The branch circuits are connected in parallel;
the thyristor V2Is connected to the first time acquisition unit 12 and/or the second time acquisition unit 16, the thyristor V2The control electrode is conducted when receiving the first overvoltage protection signal or the second overvoltage protection signal, and then the control electrode is conducted through the thyristor V2Reactor L1And diode V1The current loop is formed to sink the electrical energy at the output of the chopper 50 to reduce the output voltage at the output of the chopper 50.
The working principle of the electric energy absorption unit is as follows:
the first overvoltage protection signal generated by the first time obtaining unit 12 and the second overvoltage protection signal generated by the second time obtaining unit 16 can be used as a thyristor V2When the thyristor V is triggered2The control electrode is conducted when receiving the first overvoltage protection signal or the second overvoltage protection signal, therefore, the thyristor V2Reactor L1And diode V2A current loop is formed so that the electric energy at the output of the chopper 50 passes through the reactor L1The absorption can suppress the output voltage of the chopper, thereby reducing the output voltage at the output terminal of the chopper 50 and preventing the damage of the device connected to the rear terminal of the chopper 50 due to the excessively high output voltage.
The present embodiment is only to provide the electric energy absorption unit with a circuit structure, and certainly, the electric energy absorption unit is also implemented by using other hardware circuits, and is not limited to the embodiment.
Based on the above embodiment, as shown in fig. 3, the overvoltage protection device further includes a third voltage comparing unit 17.
A third voltage comparing unit 17 connected to the voltage detecting unit 10 and includingAnd the thyristor V2The control electrode is connected with the first voltage control threshold and the second voltage control threshold, and is used for generating a first overvoltage protection signal when the output voltage is judged to be larger than the first voltage control threshold;
wherein,
the thyristor V2The control electrode is conducted when receiving the third overvoltage protection signal, and then the third overvoltage protection signal passes through the thyristor V2Reactor L1And diode V1The current loop is formed to sink the electrical energy at the output of the chopper 50 to reduce the output voltage at the output of the chopper 50.
The third control voltage threshold is a voltage greater than the second voltage control threshold, and is referred to as the output voltage of the chopper when the output voltage of the chopper is once greater than a certain voltage and even if the duration is short, the corresponding device is damaged, and the third voltage control threshold may be equal to or slightly less than the output voltage in such a case.
The circuit structure arrangement in this embodiment can perform overvoltage protection for the above situation, and the working principle of the scheme of this embodiment is described below with reference to fig. 3:
the third voltage comparison unit 17 can be implemented by a voltage comparator or a corresponding hardware circuit, the output voltage of the chopper 50 being equal to the voltage difference between the two output lines, i.e. Ud+And Ud-The third voltage comparing unit 17 can compare the output voltage collected by the voltage detecting unit with a third voltage threshold, when the output voltage is judged to be greater than the third voltage control threshold, a third overvoltage protection signal is generated, and when the thyristor V is in a state of being controlled by the third voltage control threshold2The control electrode is conducted when receiving the third overvoltage protection signal, and then the thyristor V2Reactor L1And diode V1A current loop is formed so that the electric energy at the output of the chopper 50 passes through the reactor L1The absorption can suppress the output voltage of the chopper 50, thereby reducing the choppingThe output voltage at the output of the device 50.
Reactor L1Can suppress output voltage in a short time when the reactor L is used1When the absorbed electric energy reaches a saturation state and the electric energy at the output end of the chopper 50 can not be absorbed again, because the fuse 14 is connected in series in the input end line of the chopper 50, at the moment, because the input voltage of the chopper 50 is a third voltage control threshold value and is higher than the voltage in a normal working state, the current in the input end line is rapidly increased, the fuse 14 is fused, and then the input end line of the chopper 50 is disconnected, the chopper 50 stops working, so that the high voltage at the input end of the chopper 50 can be prevented from being transmitted to corresponding equipment at the rear end, and the corresponding equipment can be protected in time.
It should be noted that the time for the reactor to absorb the electric energy to suppress the output voltage of the chopper should be longer than the action time of the fuse, that is, the time from when the output voltage of the chopper is greater than the third voltage control threshold value to when the reactor starts to absorb the electric energy to reach the saturation state is longer than the time from the normal state to the fusing of the fuse, so as to achieve the effect of timely protection.
For example, the input voltage of the chopper is DC1800V, the output voltage after the voltage reduction by the chopper is DC600V, at this time, a reactor with the inductance of 500 muH can be selected, and a fuse which is fused within 0.1ms when the current is 6000A is selected, at this time, the time from the beginning of the electric energy absorption of the reactor to the saturation state is 1.7ms which is far longer than the 0.1ms action time of the fuse, so that the system action requirement can be met, and the effect of timely protection can be achieved.
In the embodiment, through the arrangement of the circuit structure, a three-level overvoltage protection function can be realized, when the output voltage of the chopper is greater than a first voltage control threshold and the duration time is greater than a first preset time, the electric energy at the output end of the chopper can be absorbed through the electric energy absorption unit, so that the output voltage of the chopper is reduced, the damage to corresponding equipment connected to the rear end of the chopper due to overhigh output voltage is prevented, and the function of one-level overvoltage protection is realized; when the output voltage of the chopper is further increased to be larger than a second voltage control threshold value and the duration time is longer than second preset time, the electric energy at the output end of the chopper can be absorbed through the electric energy absorption unit, so that the output voltage of the chopper is reduced, and the secondary overvoltage protection effect is realized; when the output voltage of the chopper is increased by one grade again and is larger than the third voltage control threshold value, the electric energy at the output end of the chopper is absorbed through the reactor, so that the output voltage of the chopper is reduced, and the effect of three-level overvoltage protection is achieved.
In another embodiment, the overvoltage protection device further comprises a support capacitor C, which is connected in parallel to the output line of the chopper 50.
The support capacitor is used as an energy storage element, and can play a role in inhibiting the output voltage fluctuation of the chopper, so that the output voltage is more stable, and more stable working voltage is provided for corresponding equipment arranged at the rear end of the chopper.
The embodiment of the invention also provides a chopper, wherein the chopper is provided with the overvoltage protection device provided by the embodiment of the invention, the voltage detection unit and the electric energy absorption unit in the overvoltage protection device are respectively arranged in the output end line of the chopper, and the fuse in the overvoltage protection device is connected in series in the input end line of the chopper.
By arranging the overvoltage protection device provided by the embodiment of the invention, the step-down chopper is not controlled to stop working once the output voltage of the chopper exceeds the voltage during normal working, but only when the output voltage exceeds the voltage during normal working due to large fluctuation of the voltage at the input end of the chopper or other reasons and lasts for a certain time, the electric energy at the output end of the chopper is absorbed through the electric energy absorption unit, so that the output voltage of the chopper is reduced, and the situation that the corresponding equipment connected to the rear end of the chopper is damaged due to overhigh output voltage is prevented.
On the basis of the above embodiment, further, in the chopper, the electric energy absorption circuit in the overvoltage protection device comprises a thyristor, a reactor and a diode, wherein the diode is connected in parallel in an output end line of the chopper.
In addition, in the chopper, the overvoltage protection device further comprises a third voltage comparison unit, wherein the third voltage comparison unit is connected with the voltage detection unit and is connected with the control electrode of the thyristor.
The overvoltage protection device can also comprise a support capacitor which is connected in parallel in the output line of the chopper.
The technical effects of the above embodiments have been described in the overvoltage protection device, and are not described herein again.
The embodiment of the invention also provides an electric locomotive which comprises a traction electric transmission system and an auxiliary converter system, wherein the auxiliary converter system comprises a three-phase inverter, the auxiliary converter system is also provided with the chopper provided by the embodiment of the invention, the input end of the chopper is connected with the middle output loop of the traction electric transmission system, and the output end of the chopper is connected with the three-phase inverter.
According to the electric locomotive provided by the embodiment of the invention, the chopper provided by the embodiment of the invention is arranged in the auxiliary converter system, the high-voltage direct current output by the intermediate output loop of the traction electric transmission system is subjected to voltage reduction processing through the chopper, and then the high-voltage direct current is output to the three-phase inverter, and the high-voltage direct current is further modulated by the three-phase inverter to generate required voltage which is used as a working voltage source to be supplied to corresponding equipment in the electric locomotive.
The chopper provided by the embodiment of the invention can prevent the damage of overhigh output voltage of the chopper to corresponding equipment connected at the rear end of the chopper, and can reduce the frequency of starting the chopper on the premise of protecting the corresponding equipment, thereby prolonging the service life of the chopper, improving the running stability of the application auxiliary converter system and further improving the running stability of the electric locomotive.
Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; while the invention has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.
Claims (9)
1. An overvoltage protection device for a chopper, comprising:
the voltage detection unit is arranged in an output end line of the chopper to collect the output voltage of the chopper;
the first voltage comparison unit is connected with the voltage detection unit and used for generating a first overvoltage pulse signal when the output voltage is judged to be larger than a first voltage control threshold value;
the first time acquisition unit is connected with the first voltage comparison unit and used for acquiring the duration of the first overvoltage pulse signal and generating a first overvoltage protection signal when the duration is judged to be larger than a first preset time;
the electric energy absorption unit is arranged at the output end of the chopper, is connected with the first time acquisition unit and is used for absorbing the electric energy at the output end of the chopper to reduce the voltage at the output end of the chopper when receiving the first overvoltage protection signal;
the fuse is used for being connected in series in an input end line of the chopper, and is fused to disconnect the input end line of the chopper when the voltage at the output end of the chopper is greater than an output voltage threshold for a set time;
the second voltage comparison unit is connected with the voltage detection unit and used for generating a second overvoltage pulse signal when the output voltage is judged to be larger than a second voltage control threshold value, and the second voltage control threshold value is larger than the first voltage control threshold value;
and the second time acquisition unit is respectively connected with the second voltage comparison unit and the electric energy absorption unit and used for acquiring the duration of the second overvoltage pulse signal, and generating a second overvoltage protection signal to send the second overvoltage protection signal to the electric energy absorption unit when the duration is judged to be greater than the second preset time, so that the electric energy absorption unit absorbs the electric energy at the output end of the chopper to reduce the output voltage at the output end of the chopper, and the second preset time is less than the first preset time.
2. The overvoltage protection device for a chopper according to claim 1, wherein:
the electric energy absorption unit comprises a diode, a thyristor and a reactor, wherein,
the diode is used for being connected in parallel in an output end line of the chopper, and a series branch of the thyristor and the reactor is connected in parallel with a branch where the diode is located;
and the control electrode of the thyristor is connected with the first time acquisition unit and/or the second time acquisition unit, and is conducted when receiving the first overvoltage protection signal or the second overvoltage protection signal, so that the electric energy at the output end of the chopper is absorbed through a current loop formed by the thyristor, the reactor and the diode, and the output voltage at the output end of the chopper is reduced.
3. The overvoltage protection device for a chopper according to claim 2, further comprising:
the third voltage comparison unit is connected with the voltage detection unit, is connected with the control electrode of the thyristor, and is used for generating a third overvoltage protection signal when the output voltage is judged to be larger than a third voltage control threshold value, and the third voltage control threshold value is larger than the second voltage control threshold value;
and the control electrode of the thyristor is conducted when receiving the third overvoltage protection signal, and then the electric energy at the output end of the chopper is absorbed through a current loop formed by the thyristor, the reactor and the diode so as to reduce the output voltage at the output end of the chopper.
4. The overvoltage protection device for a chopper according to claim 1, further comprising:
and the support capacitor is connected in parallel with the output end line of the chopper.
5. A chopper, characterized by: the chopper is provided with the overvoltage protection device as claimed in any one of claims 1 to 4, a voltage detection unit and an electric energy absorption unit in the overvoltage protection device are respectively arranged in an output end line of the chopper, and a fuse in the overvoltage protection device is connected in series in an input end line of the chopper.
6. The chopper according to claim 5, wherein:
the electric energy absorption circuit in the overvoltage protection device comprises a thyristor, a reactor and a diode, wherein the diode is connected in parallel in an output end line of the chopper.
7. The chopper according to claim 6, wherein:
the overvoltage protection device further comprises a third voltage comparison unit, wherein the third voltage comparison unit is connected with the voltage detection unit and is connected with the control electrode of the thyristor.
8. The chopper according to any one of claims 5 to 7, wherein:
the overvoltage protection device also comprises a support capacitor which is connected in parallel in an output end line of the chopper.
9. An electric locomotive comprising a traction electric transmission system and an auxiliary conversion system, wherein the auxiliary conversion system comprises a three-phase inverter, and the auxiliary conversion system is further provided with a chopper as claimed in any one of claims 5 to 8, the input end of the chopper is connected with the intermediate output loop of the traction electric transmission system, and the output end of the chopper is connected with the three-phase inverter.
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| CN201210370346.1A CN103715656B (en) | 2012-09-28 | 2012-09-28 | The over-pressure safety device of chopper, chopper and electric locomotive |
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| CN201210370346.1A CN103715656B (en) | 2012-09-28 | 2012-09-28 | The over-pressure safety device of chopper, chopper and electric locomotive |
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| CN103715656B true CN103715656B (en) | 2016-06-29 |
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| CN106786431B (en) * | 2016-11-28 | 2019-05-21 | 株洲中车时代电气股份有限公司 | It is a kind of for preventing the pre-control method and device of overvoltage in subway train |
| CN109066579B (en) * | 2018-09-20 | 2020-02-07 | 重庆惠科金渝光电科技有限公司 | Overvoltage protection method and device |
| CN112636564B (en) * | 2020-11-30 | 2022-02-22 | 珠海格力电器股份有限公司 | Converter control method and device, converter, electronic device and storage medium |
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