Rail transit super-capacitor energy storage system

Abstract

The invention provides a rail transit super-capacitor energy storage system which comprises two super-capacitor energy storage modules, each energy storage module is composed of a bidirectional converter module, a super-capacitor module, a module management communication module and an energy management communication module, the super-capacitor module is connected to a 1500V bus through the bidirectional converter module, and the module management communication module is connected to the energy management communication module through the bidirectional converter module. The module management communication module is connected with each modularized bidirectional DC-DC converter in the bidirectional converter module, each energy storage module is provided with a related energy management communication module, and the energy storage system operation data is acquired and recorded through corresponding recording and control configuration software. And meanwhile, through digital communication connected with the energy management module, the whole super-capacitor energy storage system is controlled. According to the invention, free seamless switching of each working mode of the super-capacitor energy storage system can be realized according to the change of the bus voltage, and the problem of instability caused by system mode jump due to voltage detection interference is avoided.

Description

Technical Field

[0001] The present invention belongs to the field of rail transit and relates to a rail transit supercapacitor energy storage system. Background Art

[0002] Urban rail transit is an important part of the urban public transport system, having the advantages of large transportation capacity, safety, comfort, convenience and speed. As a punctual public transport vehicle, urban rail transit needs to start and brake frequently. Since traditional traction power supply substations cannot absorb energy reversely, the excess energy generated during vehicle regenerative braking is wasted, which not only fails to save energy but also causes other systems to consume energy. As an energy storage unit, supercapacitors can meet the high power requirements of frequent starting, acceleration and climbing of rail transit, and at the same time can recover large amounts of energy during braking. As a power supply system, it has been recognized as the best way to solve the development of rail transit and hybrid electric vehicles.

[0003] Due to the numerous advantages of supercapacitors, the application of supercapacitors to the energy storage systems of buses has been gradually promoted in big cities such as Shanghai, Guangzhou and Beijing. However, the application in rail transit is still very few. The rail transit supercapacitor energy storage technology is mostly controlled by large companies in Western developed countries such as Siemens and Bombardier. Therefore, for China's huge rail transit network, it is urgent to develop a leading brand of rail transit supercapacitor energy storage technology with independent products. Summary of the Invention

[0004] 1. Technical problems to be solved:

[0005] How to apply supercapacitors to rail transit.

[0006] 2. Technical solutions:

[0007] To solve the above problems, the present invention provides a rail transit supercapacitor energy storage system, including two supercapacitor energy storage modules. Each energy storage module consists of a bidirectional converter module, a supercapacitor module, a module management and communication module, and an energy management and communication module. The supercapacitor module is connected to a 1500V bus through the bidirectional converter module. The module management and communication module is connected to each modular bidirectional DC-DC converter in the bidirectional converter module. Relevant energy management and communication modules are configured in each energy storage module. Through corresponding recording and control configuration software, the acquisition and recording of the operation data of the energy storage system are realized. At the same time, through digital communication connected to the energy management module, the control of the entire supercapacitor energy storage system is realized.

[0008] The input voltage range of the bidirectional DC-DC converter is 1200V to 1800V, and the rated voltage is 1500V; the output voltage range is 400V to 800V, and the rated voltage is 600V; the output current is 10A; the rated power is 5kW; the switching frequency is 50kHz.

[0009] The bidirectional DC-DC converter is a three-level DC-DC converter.

[0010] The three-level DC-DC converter includes a flying capacitor, four switching tubes, a filter inductor, a high-end voltage, a low-end voltage, a high-voltage terminal capacitor, and a low-voltage terminal capacitor. The four switching tubes are the first switching tube, the second switching tube, the third switching tube, and the fourth switching tube respectively. In the steady state, the voltage of the flying capacitor is half of the input voltage, that is The first switching tube and the fourth switching tube conduct complementarily, and the second switching tube and the third switching tube conduct complementarily; the first switching tube and the second switching tube Q2, the third switching tube and the fourth switching tube work alternately, and their drive signals have a phase angle difference of 180°.

[0011] When charging the super capacitor, the bidirectional DC-DC converter is in Buck mode, and the duty cycle D = U o / U i , when discharging the electricity in the super capacitor to the system, the bidirectional DC-DC converter is in Boost mode, and the duty cycle D = (U o -U i ) / U i .

[0012] Control the duty cycle D of the first switching tube, the second switching tube, the third switching tube, and the fourth switching tube to be divided into two modes: D>0.5 and D<0.1. In Buck mode, the first switching tube and the second switching tube are defined as the main control switching tubes, and the third switching tube and the fourth switching tube are the controlled tubes. In Boost mode, the third switching tube and the fourth switching tube are defined as the main control switching tubes, and the first switching tube and the second switching tube are the controlled tubes.

[0013] 3. Beneficial effects:

[0014] In the present invention, the free seamless switching of each working mode of the super capacitor energy storage system can be realized according to the change of the bus voltage, avoiding the unstable problem caused by the system mode jump due to the voltage detection interference. Description of the drawings

[0015] Figure 1 is a schematic diagram of the present invention.

[0016] Figure 2 is a schematic diagram of the three-level Buck-Boost bidirectional converter circuit.

[0017] Figure 3 It is a waveform schematic diagram at the moment when D > 0.5. Specific implementation manners

[0018] The present invention will be described in detail below in conjunction with the accompanying drawings and embodiments.

[0019] As Figure 1 shown, the present invention provides a rail transit supercapacitor energy storage system, including two supercapacitor energy storage modules. Each energy storage module consists of a bidirectional converter module, a supercapacitor module, a module management and communication module, and an energy management and communication module.

[0020] The supercapacitor module is connected to the 1500V bus through the bidirectional converter module. By controlling the bidirectional converter module, active management of the supercapacitor energy can be achieved.

[0021] When the bus voltage drops or rises, the supercapacitor discharges or charges, thereby playing a role in suppressing the bus voltage fluctuation.

[0022] The module management and communication module is used to control the coordinated operation of each modular bidirectional DC-DC converter in the bidirectional converter module. At the same time, relevant energy management and communication modules are configured in each energy storage module to realize the monitoring and control of their respective energy storage modules. Through the corresponding recording and control configuration software, the acquisition and recording of the operation data of the energy storage system are realized. At the same time, through the digital communication with the energy management module, the control of the entire supercapacitor energy storage system can be realized.

[0023] In one embodiment, the bidirectional DC-DC converter is used in the rail energy recovery system of the supercapacitor. Input voltage range: 1200V - 1800V, rated voltage is 1500V; output voltage range: 400V - 800V, rated voltage is 600V; output current: 10A; rated power: 5kW; switching frequency: 50kHz.

[0024] In the energy storage converter, the most commonly used is the two-level Buck-Boost bidirectional converter. The two-level converter has a simple structure and relatively easy control. However, in a high-voltage system, this circuit requires a relatively high voltage stress for the switching tube, it is difficult to select a high-voltage switching tube, the value of the filter inductor is relatively large, and the dynamic response needs to be improved.

[0025] The three-level Buck-Boost bidirectional converter is an improved type of the two-level converter structure. The voltage stress of the switching tube of the three-level converter is half of the input voltage, the switching frequency is doubled, the output filter inductor is small, and the response speed is high. The present invention uses a three-level DC-DC converter as the bidirectional converter of the supercapacitor energy storage device.

[0026] As Figure 2As shown, the three-level DC-DC converter includes a flying capacitor C fiy , four switching tubes, a filter inductor L, a high-end voltage V H , a low-end voltage V L , a high-voltage terminal capacitor C H and a low-voltage terminal capacitor C L . Among them, the four switching tubes are the first switching tube Q1, the second switching tube Q2, the third switching tube Q3, and the fourth switching tube Q4. In the steady state, the flying capacitor C fly , the voltage is half of the input voltage, that is The first switching tube Q1 and the fourth switching tube Q4 conduct complementarily, and the second switching tube Q2 and the third switching tube Q3 conduct complementarily; the first switching tube Q1 and the second switching tube Q2, the third switching tube Q3 and the fourth switching tube Q4 work alternately, and their drive signals have a phase angle difference of 180°.

[0027] When charging the super capacitor, the bidirectional DC-DC converter is in Buck mode, and the duty cycle D = U o / U i . When discharging the electricity in the super capacitor to the system, the bidirectional DC-DC converter is in Boost mode, and the duty cycle D = (U o -U i ) / U i .

[0028] Control the duty cycles D of the first switching tube Q1, the second switching tube Q2, the third switching tube Q3, and the fourth switching tube Q4 to be divided into two modes: D>0.5 and D<0.1. In Buck mode, the first switching tube Q1 and the second switching tube Q2 are defined as the main control switching tubes, and the third switching tube Q3 and the fourth switching tube Q4 are the controlled tubes. In Boost mode, the third switching tube Q3 and the fourth switching tube Q4 are defined as the main control switching tubes, and the first switching tube Q1 and the second switching tube Q2 are the controlled tubes.

[0029] As shown in Fig. 3, for the driving waveform at the moment of D>0.5, three levels of the high-end voltage V H , half of the high-end voltage V H / 2 , and 0 can be seen from the vAB waveform. For D>0.5 in Buck mode, it is the control duty cycle D>0.5 of the first switching tube Q1 and the second switching tube Q2. For D>0.5 in Boost mode, it is the control duty cycle D>0.5 of the third switching tube Q3 and the fourth switching tube Q4. The current directions flowing through the inductor L in the two modes are opposite, so that bidirectional energy control can be achieved.

Claims

1. A rail transit supercapacitor energy storage system, characterized in that: It includes two supercapacitor energy storage modules, each of which consists of a bidirectional converter module, a supercapacitor module, a module management communication module and an energy management communication module. The supercapacitor module is connected to the 1500V bus through the bidirectional converter module. The module management communication module is connected to each modular bidirectional DC-DC converter in the bidirectional converter module. A relevant energy management communication module is configured in each of the energy storage modules. The collection and recording of the energy storage system operation data are realized through the corresponding recording and control configuration software. At the same time, the control of the entire supercapacitor energy storage system is realized through the digital communication connected to the energy management module.

2. The rail transit supercapacitor energy storage system according to claim 1, characterized in that: The bidirectional DC-DC converter has an input voltage range of 1200V to 1800V and a rated voltage of 1500V; an output voltage range of 400V to 800V and a rated voltage of 600V; an output current of 10A; a rated power of 5kW; and a switching frequency of 50kHz.

3. The rail transit supercapacitor energy storage system according to claim 2, characterized in that: The bidirectional DC-DC converter is a three-level DC-DC converter.

4. The rail transit supercapacitor energy storage system according to claim 3, characterized in that: The three-level DC-DC converter includes a flying capacitor (C fiy ), four switch tubes, filter inductor (L), high-end voltage (V H ), low-side voltage (V L ), high voltage terminal capacitor (C H ) and the low voltage side capacitor (C L ), where the four switches are the first switch (Q1), the second switch (Q2), the third switch (Q3) and the fourth switch (Q4). In steady state, the flying capacitor (C fly ) is half of the input voltage, that is The first switch tube (Q1) and the fourth switch tube (Q4) are complementary turned on, and the second switch tube (Q2) and the third switch tube (Q3) are complementary turned on; the first switch tube (Q1) and the second switch tube (Q2), the third switch tube (Q3) and the fourth switch tube (Q4) work alternately, and their driving signals differ in phase angle by 180°.

5. The rail transit supercapacitor energy storage system according to claim 4, characterized in that: To charge the supercapacitor, the bidirectional DC-DC converter is in Buck mode, and the duty cycle D = U o / U i , the charge in the supercapacitor is discharged into the system, the bidirectional DC-DC converter is in Boost mode, and the duty cycle D=(U o -U i ) / U i .

6. The rail transit supercapacitor energy storage system according to claim 5, characterized in that: The duty cycle D of the first switch tube (Q1), the second switch tube (Q2), the third switch tube (Q3) and the fourth switch tube (Q4) is controlled into two modes: D>0.5 and D<0.

1. In the Buck mode, the first switch tube (Q1) and the second switch tube (Q2) are set as master switch tubes, and the third switch tube (Q3) and the fourth switch tube (Q4) are controlled tubes. In the Boost mode, the third switch tube (Q3) and the fourth switch tube (Q4) are set as master switch tubes, and the first switch tube (Q1) and the second switch tube (Q2) are controlled tubes.

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