A tram and a power supply system therefor

Abstract

This application discloses a tram and its power supply system, relating to the field of tram technology. The power supply system includes an auxiliary inverter, a fuel cell, a power battery, and an insulation monitoring device. The fuel cell and power battery are connected in parallel via a busbar. The busbar connects the traction inverter and air conditioning unit within the tram. Furthermore, based on the parallel connection of the fuel cell and power battery, the pantograph and external contact network of the original technology are eliminated, allowing the current in the power supply circuit to be conducted entirely within the tram itself, eliminating the need for return current via the running rail. This isolates the high-voltage current path from the running rail, reducing the risk of electrolytic corrosion to trackside metal structures, underground pipelines, and signaling equipment caused by stray currents. Moreover, this application also monitors the leakage current of the busbar using an insulation monitoring device, and uses this leakage current to detect busbar grounding faults, improving safety and reliability.

Description

Technical Field

[0001] This application relates to the field of tram technology, and more particularly to a tram and its power supply system. Background Technology

[0002] As an important component of urban public transportation, trams typically use external electricity as their power source. Power is supplied to the main circuit of the vehicle via the overhead contact line and pantograph, and traction and onboard power needs are met through traction inverters, auxiliary inverters, and other equipment. While this power supply method is technologically mature and widely used, the running rails usually serve as the current return path during vehicle operation. This can easily lead to stray currents in and around the track, posing a risk of electrolytic corrosion to trackside metal structures, underground pipelines, and signaling equipment, thus affecting the long-term safe operation of the system. Summary of the Invention

[0003] In view of the above problems, this application provides a tram and its power supply system, which reduces the risk of electrolytic corrosion and enables busbar grounding fault detection. The specific solution is as follows:

[0004] The first aspect of this application provides a power supply system for a tram, comprising: an auxiliary inverter, a fuel cell, a power battery, and an insulation monitoring device; wherein,

[0005] The positive electrode of the fuel cell is connected to the positive electrode of the power battery through the positive electrode of the busbar, and the negative electrode of the fuel cell is connected to the negative electrode of the power battery through the negative electrode of the busbar.

[0006] The busbar is used to connect the traction inverter and air conditioning unit in the tram.

[0007] The positive terminal of the DC side of the auxiliary inverter is connected to the positive terminal of the bus, and the negative terminal of the DC side of the auxiliary inverter is connected to the negative terminal of the bus.

[0008] The insulation monitoring device is installed on the busbar and connected to the positive and negative poles of the busbar and ground. It is used to monitor the leakage current of the busbar and to detect the busbar grounding fault based on the leakage current.

[0009] In one possible implementation, the insulation monitoring device includes: monitoring equipment and detection equipment;

[0010] The monitoring equipment is used to monitor the leakage current of the busbar;

[0011] The detection equipment is used to detect whether a grounding fault has occurred on the busbar based on the leakage current.

[0012] In one possible implementation, the monitoring device includes: a DC leakage current detection transformer and a resistance module;

[0013] The resistor module is grounded, connected in parallel with the power battery and between the positive and negative terminals of the busbar, so that when the busbar is grounded, the current will flow back to the busbar through the resistor module.

[0014] The DC leakage current detection transformer is used to detect the leakage current of the bus.

[0015] In one possible implementation, the resistor module includes: a first resistor, a second resistor, and a third resistor;

[0016] The first resistor and the second resistor are connected in series between the positive and negative terminals of the busbar;

[0017] The connection point between the first resistor and the second resistor is grounded through the third resistor.

[0018] In one possible implementation, the monitoring device is integrated with the busbar in the same enclosure.

[0019] In one possible implementation, the detection device includes: an online insulation detection device;

[0020] The input terminal of the online insulation detection device is connected to the data output terminal of the monitoring device, and the online insulation detection device is used to transmit the current change data of the monitoring device to the vehicle control terminal.

[0021] In one possible implementation, the detection device further includes a test circuit for confirming whether the insulation monitoring device is functioning properly.

[0022] In one possible implementation, the test circuit includes: a button and a wound cable;

[0023] The first end of the button is connected to the power supply cable, and the second end of the button is connected to the first end of the wound cable; the button is used to control the connection between the wound cable and the power supply cable.

[0024] The second end of the wound cable is grounded, and the wound cable is wound around the current inductance ring of the DC leakage current detection transformer in the monitoring equipment with a preset number of turns, so that the DC leakage current detection transformer can collect the current signal in the wound cable.

[0025] In one possible implementation, the test circuit further includes: a grounding resistor;

[0026] The grounding resistor is located between the second end of the wound cable and ground; the grounding resistor acts as a load resistor to prevent the test circuit from being short-circuited.

[0027] A second aspect of this application provides a tram, comprising: a traction inverter, an air conditioning unit, and a power supply system for the tram as described in the first aspect or any implementation thereof; wherein,

[0028] The DC side of the traction inverter is connected to the bus in the power supply system;

[0029] The power supply terminal of the air conditioning unit is connected to the busbar.

[0030] By employing the aforementioned technical solution, the power supply system for the tram provided in this application, compared to existing tram circuit solutions that rely on overhead contact lines for power supply, can achieve power supply to the load by connecting fuel cells and power batteries in parallel via a busbar. This eliminates the need for pantographs and external contact lines in the original technology. Furthermore, since both the positive and negative poles of this busbar are located within the tram itself, the current in the corresponding power supply circuit is conducted entirely within the tram, eliminating the need for return current via the running rail. This isolates the high-voltage current path from the running rail, reducing the risk of electrolytic corrosion to trackside metal structures, underground pipelines, and signaling equipment caused by stray currents. Moreover, this application also monitors the leakage current of the busbar using an insulation monitoring device and detects busbar grounding faults based on this leakage current, thereby improving safety and reliability. Attached Figure Description

[0031] The above and other features, advantages, and aspects of the embodiments of this disclosure will become more apparent from the accompanying drawings and the following detailed description. Throughout the drawings, the same or similar reference numerals denote the same or similar elements. It should be understood that the drawings are schematic, and the originals and elements are not necessarily drawn to scale.

[0032] Figure 1 A schematic diagram of a power supply system for a tram provided in an embodiment of this application;

[0033] Figure 2 A circuit diagram of a monitoring device in the power supply system of a tram provided in an embodiment of this application;

[0034] Figure 3 Another schematic diagram of the power supply system for a tram provided in an embodiment of this application;

[0035] Figure 4 A circuit diagram of a detection device in the power supply system of a tram provided in an embodiment of this application;

[0036] Figure 5 The present application provides a node protection circuit structure for a tram. Detailed Implementation

[0037] The embodiments of this application are described below with reference to the accompanying drawings. The terminology used in the implementation section of this application is for explaining specific embodiments only and is not intended to limit the scope of this application.

[0038] The embodiments of this application will now be described with reference to the accompanying drawings. Those skilled in the art will recognize that, with technological advancements and the emergence of new scenarios, the technical solutions provided in the embodiments of this application are equally applicable to similar technical problems.

[0039] The terms "first," "second," etc., used in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such terms are interchangeable where appropriate; this is merely a way of distinguishing objects with the same attributes in the embodiments of this application. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion, so that a process, method, system, product, or apparatus that comprises a series of elements is not necessarily limited to those elements, but may include other elements not explicitly listed or inherent to those processes, methods, products, or apparatuses.

[0040] This application provides a power supply system for a tram, such as... Figure 1 The power supply system includes: an auxiliary inverter 102, a fuel cell 103, a power battery 106, and an insulation monitoring device 105; wherein:

[0041] The fuel cell 103 and the power battery 106 are connected in parallel via a bus (including a positive terminal BUS+ and a negative terminal BUS-). That is, the positive terminal of the fuel cell 103 is connected to the positive terminal of the power battery 106 via the positive terminal BUS+ of the bus, and the negative terminal of the fuel cell 103 is connected to the negative terminal of the power battery 106 via the negative terminal BUS- of the bus. In practical applications, the fuel cell 103 can be a hydrogen fuel cell, and the positive terminal BUS+ and the negative terminal BUS- of the bus can be implemented in the form of copper busbars, but are not limited to this.

[0042] The busbar is used to connect the traction inverter 101 and the air conditioning unit 104 in the tram, thereby providing DC power to the vehicle's traction system and in-vehicle air conditioning system. The DC side of the auxiliary inverter 102 is also connected to the busbar, that is, the positive terminal of the DC side of the auxiliary inverter 102 is connected to the positive terminal BUS+ of the busbar, and the negative terminal of the DC side of the auxiliary inverter 102 is connected to the negative terminal BUS- of the busbar, so that the auxiliary power system of the tram can draw power from this busbar.

[0043] In practical applications, the specific functions of the power battery 106 can include: providing power to the bus with first priority under traction conditions, and absorbing regenerative braking energy under braking conditions. In other words, the power battery 106 can be configured as the main energy storage and discharge unit of the tram. When the vehicle is in traction condition, it outputs power to the bus with first priority, providing the DC power required for traction to the traction inverter 101, thereby driving the vehicle. Simultaneously, when the vehicle is in braking condition, the power battery 106 absorbs the regenerative braking energy generated by the traction motor, achieving energy recovery and improving the system's energy utilization efficiency.

[0044] The specific functions of fuel cell 103 may include: supplying electrical energy to the bus when the output current of power battery 106 is greater than a preset current threshold, and / or when the SOC (State of Charge) of power battery 106 is less than a discharge threshold. Fuel cell 103 is configured as a continuous power supply unit, with its output terminal connected in parallel to the bus to replenish electrical energy to the bus under specific operating conditions. Specifically, when the output current of power battery 106 is greater than the preset current threshold, such as during high-power demand conditions like vehicle start-up, acceleration, or heavy-load operation, fuel cell 103 supplies electrical energy to the bus to share the discharge pressure of power battery 106; when the SOC of power battery 106 is less than the preset discharge threshold, fuel cell 103 supplies power to the bus to maintain normal vehicle operation and prevent over-discharge of power battery 106. Additionally, if there is still surplus power output from fuel cell 103 to traction inverter 101, auxiliary inverter 102, and air conditioning unit 104 via the bus, the surplus power is used to charge power battery 106. The value of the preset current threshold is not limited, as long as it can indicate that the current operating condition is one with high power demand; the value of the preset discharge threshold is also not limited, as long as it can indicate that the power battery 106 is about to be over-discharged; both can be determined according to the specific application environment.

[0045] Through the above configuration, the fuel cell 103 and the power battery 106 form a complementary hybrid power supply architecture, with both working together to provide electrical energy. This main circuit suspension design eliminates the need for pantographs and external contact networks found in existing technologies, reducing construction and maintenance costs while also minimizing energy transmission losses. Furthermore, unlike traditional trams that use pantographs for current collection and wheel-rail return, the power supply system provided in this embodiment uses a parallel power supply method between the fuel cell 103 and the power battery 106. The high-voltage DC power in the power supply circuit is transmitted within the vehicle body via a busbar. The traction inverter 101, auxiliary inverter 102, and air conditioning unit 104 are all powered by this busbar. In other words, the high-voltage portion is completely isolated from the running rail. Therefore, this embodiment can also effectively reduce stray current generation, thereby reducing the risk of electrolytic corrosion to nearby infrastructure such as trackside metal structures, underground pipelines, and signaling equipment. Moreover, this power supply method can maintain the stability of vehicle power supply under different operating conditions and slow down the aging of the power battery 106, extending its service life.

[0046] In addition, this embodiment also includes an insulation monitoring device 105, which is installed on the busbar, specifically at the load end of the power battery 106. The insulation monitoring device 105 is connected to the positive terminal BUS+, the negative terminal BUS- and the ground of the busbar, and is specifically used to monitor the leakage current of the busbar and detect the busbar grounding fault based on the leakage current.

[0047] Because the power supply system adopts a main circuit suspension design, when the busbar insulation deteriorates or a grounding fault occurs, the fault current can no longer be naturally discharged through the running rail as in traditional trams. Therefore, by setting up the insulation monitoring device 105 in this embodiment, online monitoring and fault detection of the insulation status of the tram's high-voltage DC busbar can be realized, avoiding the risk of electric shock, equipment damage, or system failure caused by insulation faults, thereby significantly improving the safety and reliability of the tram power supply system.

[0048] Based on the previous embodiment, the insulation monitoring device 105 may specifically include monitoring equipment and detection equipment, wherein:

[0049] The monitoring equipment is used to monitor the leakage current of the busbar. Specifically, it can collect the current changes between the positive and negative poles of the busbar and the vehicle body to obtain the leakage current signal that reflects the insulation status of the busbar. This leakage current signal can characterize whether there is a grounding fault in the power supply system.

[0050] The detection equipment is used to detect whether a grounding fault has occurred in the busbar. For example, by analyzing and judging the leakage current signal collected by the monitoring equipment, it can determine whether there is a decrease in insulation or an abnormal grounding in the busbar system. For example, when a busbar grounding fault occurs, the monitoring equipment can detect the change in the busbar current vector, thereby enabling the detection equipment to determine the busbar grounding fault.

[0051] In this embodiment, when the busbar is in normal insulation condition, the monitoring equipment detects that the leakage current is within a preset safe range (almost negligible). When the busbar experiences insulation degradation or a grounding fault, the monitoring equipment detects abnormal changes in the leakage current. Based on this, the detection equipment determines that there is a risk of a grounding fault on the busbar and can upload the corresponding fault information to the vehicle control terminal for subsequent safety control or alarm processing. Through the above principle, the risk of electric shock, equipment damage, or system failure caused by insulation faults can be avoided, thereby significantly improving the safety and reliability of the tram power supply system.

[0052] Based on the above embodiments, this embodiment provides an exemplary description of the implementation of the monitoring device, such as... Figure 2 As shown, the monitoring device 501 includes: a DC leakage current detection transformer JK8 and a resistor module 511; the resistor module 511 is grounded, connected in parallel with the power battery 106 and connected between the positive and negative terminals of the bus, so that when the bus is grounded, the current will flow back to the bus through the resistor module 511; the DC leakage current detection transformer JK8 is used to detect the leakage current of the bus.

[0053] The DC leakage current detection transformer JK8 is installed in the busbar circuit. By detecting the DC leakage current signal flowing through the busbar in real time, the leakage current of the busbar can be obtained. Under normal circumstances, there is no current in the resistor module 511. When the insulation state of the busbar to ground changes, the ground fault current will flow back to the busbar through the resistor module 511. The DC leakage current detection transformer JK8 can then sense the current change caused by insulation deterioration or ground fault, and can generate and output a corresponding induced signal.

[0054] In practical applications, the resistor module 511 may include Figure 2 The diagram shows: a first resistor R1, a second resistor R2, and a third resistor R3; the first resistor R1 and the second resistor R2 are connected in series between the positive terminal BUS+ and the negative terminal BUS- of the busbar, forming a voltage divider circuit to create a stable voltage reference across the busbar; the connection point of the first resistor R1 and the second resistor R2 is grounded through the third resistor R3, thereby establishing a controlled reference path between the busbar and ground, enabling the busbar system to have monitorable potential characteristics in floating ground mode; when a ground fault occurs on the busbar, the grounding current will flow back to the battery through these resistors, and the current change can be monitored by the DC leakage current detection transformer JK8; Figure 2 In the diagram, D01 is the connection port for the positive bus (BUS+), and D02 is the connection port for the negative bus (BUS-).

[0055] In this embodiment, the coordinated arrangement of the first resistor R1, the second resistor R2, and the third resistor R3 causes a change in the busbar potential when the insulation to ground decreases or a ground fault occurs, thereby causing a change in the leakage current. The DC leakage current detection transformer JK8 detects this change in leakage current and outputs the detected leakage current signal to subsequent detection equipment to determine whether a ground fault exists on the busbar.

[0056] Through the above structural design, it is possible to achieve high-sensitivity detection of bus leakage current in the tram power supply system without affecting the normal power supply of the busbar, thereby providing a reliable data basis for insulation status judgment and grounding fault detection, improving the stability of the whole vehicle power supply system and ensuring the safety of drivers and passengers.

[0057] In practical applications, this monitoring device can be integrated with the busbar in the same enclosure, such as the insulation testing box 500.

[0058] Specifically, such as Figure 3 As shown, the DC leakage current detection transformer JK8, the first resistor R1, the second resistor R2, and the third resistor R3 are all installed in the same electrical box as the busbar. The busbar is laid out along the inside of the box and can form an integrated structure with the monitoring equipment. At this time, the power battery 106 is connected in parallel with the traction inverter 101, the auxiliary inverter 102, the air conditioning unit 104, and the fuel cell 103 via the busbar after the insulation detection box 500. The first resistor R1 and the second resistor R2 are connected in series between the positive terminal BUS+ and the negative terminal BUS- of the busbar. The connection point of the first resistor R1 and the second resistor R2 is grounded through the third resistor R3. The DC leakage current detection transformer JK8 is placed next to the conductor to sense the current change on the busbar.

[0059] By integrating the monitoring equipment with the busbar, the length of external wiring between the busbar and the monitoring equipment can be reduced, minimizing interference signals introduced by excessively long cables or loose connections, thereby improving the accuracy and reliability of leakage current detection. Simultaneously, this integrated structure effectively reduces the overall space occupied by the power supply system, facilitating a more compact layout within the tram's interior.

[0060] The above integrated design achieves a high degree of integration between bus power supply and leakage current monitoring functions, which helps to improve the safety, reliability, and ease of engineering implementation of the tram power supply system.

[0061] Based on the above embodiments, the detection equipment in the power supply system of the tram may include an online insulation detection device, such as... Figure 4As shown, the data input terminal of the online insulation detection device 502 is connected to the data output terminal of the monitoring device 501. The online insulation detection device 502 is used to transmit the current change data of the monitoring device 501 to the vehicle control terminal 107. In practical applications, the online insulation detection device 502 can be installed in the driver's cab.

[0062] Specifically, such as Figure 4 As shown, after the monitoring device 501 performs real-time detection of the bus leakage current, it outputs the detected current change data to the online insulation detection device 502 through the VG signal output terminal. The online insulation detection device 502 analyzes and processes the received data to determine the insulation status of the bus.

[0063] Among them, for the online insulation detection device 502, port 1 is the power supply port; ports 3 and 4 are its internal common reference points, used to establish a stable voltage reference, signal return path and measurement zero point; port 2 is the function control terminal. When the online insulation detection device 502 is powered on, port 2 outputs a working signal to indicate that the device is running; port 5 is connected to the positive terminal +E of the DC leakage current detection transformer JK8, port 6 is grounded, port 7 is connected to the negative terminal -E of the DC leakage current detection transformer JK8, and port 8 is connected to the signal output terminal VG of the DC leakage current detection transformer JK8; port 10 is connected to port B24 of the vehicle control terminal 107, and port 11 is connected to port B30 of the vehicle control terminal 107. Ports B24 and B30 are used to form a channel for analog differential signals, which can input the signal emitted by the online insulation detection device 502 to the vehicle control terminal 107 in the form of differential analog quantities.

[0064] In this embodiment, the online insulation detection device 502 can process the leakage current change information collected by the monitoring device 501. For example, it can use simple data processing methods such as simple filtering or standardization to convert the leakage current change information into standardized insulation status data. This insulation status data is then transmitted to the vehicle control terminal 107, such as the vehicle control unit or safety monitoring unit, via the vehicle communication bus or a dedicated signal interface, thereby enabling interaction with the driver. The vehicle control terminal 107 can assess the operational safety of the power supply system based on the insulation status data and trigger alarms or take corresponding protective measures when an anomaly is detected (such as a bus grounding anomaly). By connecting the monitoring device 501 and the online insulation detection device 502, online acquisition and real-time analysis of bus leakage information are achieved. This allows the vehicle control terminal 107 to promptly grasp the insulation status of the power supply system, thereby improving the safety monitoring capability and fault response efficiency of the tram power supply system and enhancing the overall safety and reliability of the vehicle operation.

[0065] In one example, the detection equipment in the power supply system of the tram may also include a test circuit for verifying whether the insulation monitoring device 105 is functioning properly.

[0066] Specifically, before the tram is put into operation, during regular maintenance, or during operational breaks, control personnel can introduce a set of preset test current signals, such as 100mA, into monitoring device 501 from the driver's cab via a trigger test circuit to simulate the current changes when a leakage occurs in the busbar. After receiving the test current signal, monitoring device 501 generates corresponding leakage detection data and outputs the detection data to online insulation detection device 502.

[0067] The online insulation detection device 502 analyzes the received test data and uploads the analysis results to the vehicle control terminal 107. If the detection result received by the vehicle control terminal 107 is consistent with the preset test result, the insulation monitoring device 105 is determined to be working normally; if the detection result is abnormal or fails to respond correctly, the insulation monitoring device 105 is determined to be faulty, thus prompting that maintenance or replacement is required. Through this method, the functional integrity of the insulation monitoring device 105 is verified, preventing the failure of the monitoring device to detect potential safety hazards in a timely manner when a real fault occurs.

[0068] In practical applications, this test circuit can also be automatically triggered by the vehicle control terminal 107 during vehicle operation without manual intervention. Specifically, the vehicle control terminal 107 can send a test command to the test circuit during vehicle startup, parking, or within a preset safety detection cycle, causing the test circuit to inject a test current signal with a small amplitude and short duration into the DC leakage current detection transformer without affecting the normal power supply. The monitoring device 501 and the online insulation detection device 502 detect and process this test current signal and feed the detection results back to the vehicle control terminal 107 in real time.

[0069] The vehicle control terminal 107 automatically determines the working status of the insulation monitoring device 105 based on the feedback results. When an abnormality is detected, it can automatically record fault information, generate a maintenance log, or restrict the vehicle from entering a high-load operating condition. By setting a test circuit in the detection equipment and supporting both manual and automatic triggering methods, the insulation monitoring device 105 can be effectively verified without relying on a real grounding fault, ensuring the long-term stable and reliable operation of the monitoring system, thereby further improving the safety assurance capability of the tram power supply system.

[0070] like Figure 4As shown, the test circuit may specifically include: a button K2 and a wound cable; the first end of the button K2 is connected to the power supply cable, and the second end of the button K2 is connected to the first end of the wound cable; the button K2 is used to control the connection between the wound cable and the power supply cable; the wound cable is wound around the inductance magnetic ring of the DC leakage current detection transformer JK8 in the monitoring device 501 with a preset number of turns, so that the DC leakage current detection transformer JK8 can collect the current signal in the wound cable.

[0071] In practice, when switch K1 is closed, the entire insulation monitoring device 105 begins to operate. Specifically, when a functional test of the insulation monitoring device 105 is required, the operator presses button K2, allowing the current in the power supply cable to flow through the wound cable. Since the wound cable is wound around the inductance magnetic ring of the DC leakage current detection transformer JK8, the current in the magnetic ring generates a magnetic field change equivalent to the bus leakage current, thereby causing the DC leakage current detection transformer JK8 to output a corresponding detection signal. By adjusting the number of turns of the wound cable and the magnitude of the power supply current, leakage current of different amplitudes can be simulated to verify the detection sensitivity and response capability of the monitoring device 501 under different operating conditions.

[0072] In practical applications, button K2 can be either normally open or normally closed and connected to the vehicle control terminal 107 or maintenance interface. When the vehicle is in maintenance mode or safety detection mode, the vehicle control terminal 107 can send a control signal to button K2, causing button K2 to automatically conduct, thereby driving the test circuit to work. At this time, the test current generated in the wound cable is collected by the DC leakage current detection transformer JK8, and the obtained detection result is transmitted to the online insulation detection device 502 and the vehicle control terminal 107 to automatically determine whether the insulation monitoring device 105 is in normal working condition.

[0073] Through the above structural design and two implementation methods, the test circuit can conveniently and reliably simulate leakage current conditions without damaging the normal power supply structure of the busbar, and perform functional verification on the DC leakage current detection transformer JK8 and the entire insulation monitoring device 105, thereby improving the safety and maintainability of the tram power supply system insulation monitoring system.

[0074] In addition, the test circuit may also include Figure 4 As shown: Grounding resistor R4; the first end of the grounding resistor R4 is connected to the second end of the wound cable, and the second end of the grounding resistor R4 is grounded.

[0075] The grounding resistor R4 acts as a load resistor to prevent short circuits in the test circuit. Specifically, when the operator or vehicle control terminal 107 triggers button K2 to activate the test circuit, the current in the power supply cable flows through button K2 into the wound cable and is discharged to ground through the grounding resistor R4. Since the resistance of the grounding resistor R4 is a preset safety value, it effectively limits the test current, thus preventing damage to the power supply cable, button K2, or the DC leakage current detection transformer JK8 due to excessive current. Simultaneously, the grounding resistor R4 ensures that the test circuit forms a stable and controllable closed loop, enabling the DC leakage current detection transformer JK8 to continuously and stably acquire the test current signal.

[0076] In practical applications, the grounding resistor R4 can be a high-stability resistor element, and its resistance value is configured according to the vehicle power supply voltage level and the detection range of the DC leakage current detection transformer JK8. By changing the resistance value of the grounding resistor R4, leakage current conditions of different amplitudes can be simulated without changing the overall structure of the test circuit, so as to verify the detection accuracy of the insulation monitoring device 105 under various leakage current levels and the rationality of the alarm threshold setting.

[0077] Through the above configuration, the grounding resistor R4 not only effectively avoids the risk of direct short circuit in the test circuit, but also makes the grounding loop exhibit controlled impedance characteristics, thereby suppressing the disorderly flow of stray current. Therefore, when the fuel cell-powered tram operates in conjunction with existing trams, it can avoid the generation of stray currents on the running rails due to the grounding design of the existing trams, and further prevent these stray currents from returning to the vehicle body and equipment through the running rails and grounding wires, thus preventing interference with the signal transmission and equipment operation of the fuel cell-powered tram. This improves the stability and anti-interference capability of the power supply system and related equipment.

[0078] Another embodiment of this application also provides a tram, such as Figure 1 or Figure 3 The diagram shows a traction inverter 101, an air conditioning unit 104, and a power supply system for the tram. The DC side of the traction inverter 101 is connected to the busbar in this power supply system. The power supply terminal of the air conditioning unit 104 is connected to the busbar to draw power from it. The specific structure and working principle of this power supply system can be found in the above embodiments, and will not be repeated here.

[0079] The power supply system can be installed inside the tram body or in the equipment compartment under the tram. The busbars in the power supply system are electrically connected to the traction inverter 101 and the air conditioning unit 104, respectively. The traction inverter 101 is connected to the traction motor and is used to convert the DC power provided by the power supply system into AC power to drive the vehicle. The auxiliary inverter 102 is used to supply power to auxiliary electrical equipment such as on-board lighting, control systems, and communication equipment.

[0080] During normal vehicle operation, the power battery 106 and fuel cell 103 work together to provide electrical energy to the vehicle. Specifically, when the vehicle is in traction operation, the power battery 106 prioritizes supplying power to the bus, and the traction inverter 101 obtains electrical energy from the bus and converts it into AC power to drive the vehicle's traction motor. When the output current of the power battery 106 exceeds a preset current threshold, or when the SOC of the power battery 106 is lower than the discharge threshold, the fuel cell 103 intervenes and replenishes electrical energy to the bus to share the load of the power battery 106 and ensure the stable operation of the traction system. That is, during start-up, acceleration, and low-to-medium load operation, the power battery 106 acts as the main power supply unit to supply power to the bus; during long-term operation, high load, or when the SOC of the power battery 106 is low, the fuel cell 103 continuously supplies power to the bus or supplies power together with the power battery 106 to ensure the vehicle's range and operational stability.

[0081] When the vehicle is braking, the traction inverter 101 operates in energy feedback mode, feeding back the regenerative braking energy generated by the traction motor to the bus, where it is absorbed and stored by the power battery 106, thereby realizing energy recovery and improving the energy utilization efficiency of the tram.

[0082] As described in the above embodiments, the power supply system uses an insulation monitoring device 105 connected to the busbar to collect real-time changes in the busbar leakage current and determine whether a grounding fault exists on the busbar. When abnormal leakage or a decreasing insulation trend is detected, the monitoring data can be uploaded to the vehicle control terminal 107 to provide a basis for the safe control of the vehicle's power supply. The vehicle control terminal 107 can adjust the vehicle's operating status, such as limiting traction power, disconnecting some loads, or issuing alarm information to ensure the safety of the vehicle and passengers.

[0083] In practical applications, the power supply system can work in conjunction with the vehicle control terminal 107. Based on traction power requirements, auxiliary load status, and the SOC information of the power battery 106, the vehicle control terminal 107 coordinates and controls the output of the fuel cell 103 and the power battery 106, and comprehensively manages the operating status of the power supply system by combining the monitoring results fed back by the insulation monitoring device 105. When an abnormality in the power supply circuit or an insulation risk is detected, the vehicle control terminal 107 can take measures such as power limiting operation, disconnecting part of the load, or issuing a fault alarm to improve the safety and reliability of the vehicle operation.

[0084] Through the above system structure, the tram power supply system in this embodiment realizes the coordinated power supply of fuel cells and power batteries, the unified power supply of traction and auxiliary loads, and the online insulation monitoring of the power supply circuit. This not only improves the energy utilization efficiency of the vehicle, but also significantly enhances the safety and stability of the power supply system operation, making it suitable for application scenarios such as low-capacity hydrogen-powered trams.

[0085] like Figure 5 As shown, the tram may also include a PE (Protective Earthing) circuit; the first part is the car body 109 and the PE circuit connected to the car body 109, the second part is a PE branch used to reduce grounding impedance and improve the discharge capacity of fault current, and the third part is the bogie 108; and a resistor R5 is connected in series between the detection terminal X01 and the car body, and a resistor R6 is connected in series between the detection terminal X02 and the car body; the detection terminals X01 and X02 are used to detect whether the grounding circuit is complete. When a fault occurs, the fault current flows to the ground through the PE circuit via the car body 109, avoiding voltage floating on the bogie 108, which could lead to electric shock or electrical corrosion; in addition, the detection terminals X01 and X02 can also detect faults and transmit the fault information to the vehicle control terminal. Specifically, the PE circuit reliably connects the bogie 108 to the car body 109 through multiple large-section PE wires, forming a low-impedance fault current discharge channel. At the same time, an independent grounding detection branch is set up to monitor the grounding continuity through grounding resistance and detection terminals. This can avoid step voltage from causing personal injury to the driver and passengers, and can also improve the maintainability and reliability of the grounding system while ensuring the safety of personnel and equipment.

[0086] This embodiment uses a hybrid power supply mode of fuel cells and power batteries to provide energy for the tram, eliminating the traditional overhead contact line and pantograph structure, thereby reducing energy loss during transmission and lowering the overall equipment configuration cost. Simultaneously, because the power supply system supplies power to the traction inverter and air conditioning unit via the busbar and is electrically isolated from the track system, the risk of stray currents propagating through the track and causing electrolytic corrosion to the infrastructure is fundamentally avoided.

[0087] Furthermore, this embodiment utilizes the coordinated setup of the insulation monitoring device and the PE grounding protection circuit. On the one hand, it employs monitoring equipment and online insulation detection devices to monitor the bus leakage status online and transmits the monitoring data to the vehicle control terminal. On the other hand, the PE grounding protection circuit provides a safe and low-impedance discharge path for fault currents. This effectively reduces stray current interference and improves the operational safety, reliability, and maintainability of the vehicle's power supply system in the context of mixed operation of existing trams and hydrogen-powered trams.

[0088] It should be noted that each embodiment in this specification focuses on the differences from other embodiments, and the same or similar parts between the embodiments can be referred to accordingly. For the apparatus embodiments, since they are basically similar to the method embodiments, the description is relatively simple, and the relevant parts can be referred to the descriptions of the method embodiments.

[0089] Finally, it should be noted that in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0090] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

[0091] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A power supply system for a tram, characterized in that, include: Auxiliary inverter, fuel cell, power battery, and insulation monitoring device; among which, The positive electrode of the fuel cell is connected to the positive electrode of the power battery through the positive electrode of the busbar, and the negative electrode of the fuel cell is connected to the negative electrode of the power battery through the negative electrode of the busbar. The busbar is used to connect the traction inverter and air conditioning unit in the tram. The positive terminal of the DC side of the auxiliary inverter is connected to the positive terminal of the bus, and the negative terminal of the DC side of the auxiliary inverter is connected to the negative terminal of the bus. The insulation monitoring device is installed on the busbar and connected to the positive and negative poles of the busbar and ground. It is used to monitor the leakage current of the busbar and to detect the busbar grounding fault based on the leakage current.

2. The power supply system for the tram according to claim 1, characterized in that, The insulation monitoring device includes: monitoring equipment and detection equipment; The monitoring equipment is used to monitor the leakage current of the busbar; The detection equipment is used to detect whether a grounding fault has occurred on the busbar based on the leakage current.

3. The power supply system for the tram according to claim 2, characterized in that, The monitoring equipment includes: a DC leakage current detection transformer and a resistance module; The resistor module is grounded, connected in parallel with the power battery and between the positive and negative terminals of the busbar, so that when the busbar is grounded, the current will flow back to the busbar through the resistor module. The DC leakage current detection transformer is used to detect the leakage current of the bus.

4. The power supply system for the tram according to claim 3, characterized in that, The resistor module includes: a first resistor, a second resistor, and a third resistor; The first resistor and the second resistor are connected in series between the positive and negative terminals of the busbar; The connection point between the first resistor and the second resistor is grounded through the third resistor.

5. The power supply system for the tram according to claim 2, characterized in that, The monitoring equipment and the busbar are integrated into the same enclosure.

6. The power supply system for the tram according to claim 2, characterized in that, The testing equipment includes: an online insulation testing device; The input terminal of the online insulation detection device is connected to the data output terminal of the monitoring device, and the online insulation detection device is used to transmit the current change data of the monitoring device to the vehicle control terminal.

7. The power supply system for the tram according to claim 6, characterized in that, The testing equipment further includes a test circuit, which is used to confirm whether the insulation monitoring device is functioning properly.

8. The power supply system for the tram according to claim 7, characterized in that, The test circuit includes: a button and a wound cable; The first end of the button is connected to the power supply cable, and the second end of the button is connected to the first end of the wound cable; the button is used to control the connection between the wound cable and the power supply cable. The second end of the wound cable is grounded, and the wound cable is wound around the current inductance ring of the DC leakage current detection transformer in the monitoring equipment with a preset number of turns, so that the DC leakage current detection transformer can collect the current signal in the wound cable.

9. The power supply system for the tram according to claim 8, characterized in that, The test circuit also includes: a grounding resistor; The grounding resistor is located between the second end of the wound cable and ground; the grounding resistor acts as a load resistor to prevent the test circuit from being short-circuited.

10. A tram, characterized in that, include: The traction inverter, the air conditioning unit, and the power supply system for the tram as described in any one of claims 1 to 9; wherein, The DC side of the traction inverter is connected to the bus in the power supply system; The power supply terminal of the air conditioning unit is connected to the busbar.

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