Ship traction inverter

Abstract

This invention discloses a marine traction inverter, comprising a PCB circuit board with several power modules. The input side of each power module is connected to an input copper bus, and the output side is connected to an output copper bus. An input DC bus capacitor is mounted on the input copper bus, and a current sensor is connected to the output copper bus. The PCB circuit board is connected to a heat sink located on the other side of the power modules. The PCB circuit board includes a DSP controller, a drive circuit, a sampling circuit, a protection circuit, an auxiliary power supply circuit, and a communication circuit. A current amplification circuit connected to the drive circuit is also present on the PCB circuit board. This inverter achieves efficient control through an embedded chip and optimizes the layout between the power devices, DC bus capacitor, and control circuit board, reducing the use of connecting cables. This inverter simplifies the heat dissipation structure, improves system reliability, and reduces design and manufacturing costs.

Description

Technical Field

[0001] This invention relates to the field of ship electric propulsion technology, and more specifically to a ship traction inverter. Background Technology

[0002] The traction inverter is a core component of a ship's electric propulsion system, used to convert direct current (DC) to alternating current (AC) to drive motors. Existing traction inverters typically suffer from the following problems: large size, low integration, and difficulty in adapting to the limited space requirements of ships.

[0003] Existing marine traction inverters typically employ a discrete design, with power modules, drive modules, control modules, and cooling systems operating independently, lacking effective modular integration. The layout of power devices (such as IGBT modules), DC bus capacitors, and control circuit boards is not optimized, and connecting cables and structural components occupy a significant amount of extra space, resulting in low system integration.

[0004] Cooling systems often employ liquid cooling, which is complex in structure and has high maintenance costs. Existing marine traction inverters generate a large amount of heat during high-power operation. To ensure the stable operation of power devices and control circuits, liquid cooling technology is commonly used in cooling systems. While liquid cooling systems offer certain advantages in heat dissipation efficiency, their complex structure includes multiple components. These components not only increase the system's size and weight but also significantly raise design and manufacturing costs.

[0005] The control system is complex and costly, making it difficult to meet the requirements of high-efficiency and high-reliability operation. Existing marine traction inverter control systems handle multiple functions, including operating control algorithms, signal sampling, system protection, communication, and auxiliary power management. However, traditional designs exhibit significant complexity and shortcomings in implementing these functions. For example, to achieve accurate sampling of parameters such as motor current, voltage, and speed, traditional designs require independent analog-to-digital converter (ADC) modules, signal conditioning circuits (such as operational amplifiers and low-pass filters), and isolation circuits, increasing the number of components and board area. Overcurrent, overvoltage, and overtemperature protection functions are typically implemented through discrete comparator circuits, relays, or dedicated protection chips. These circuits are separated from the main control unit, requiring additional signal interfaces and logic processing modules. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a ship traction inverter with high integration, low cost and intelligent control.

[0007] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows: a ship traction inverter, including a PCB circuit board, a plurality of power modules are provided on the PCB circuit board, an input copper busbar is connected to the input side of the power module, an output copper busbar is connected to the output side of the power module, a plurality of input DC bus capacitors are provided on the input copper busbar, a current sensor is connected to the output copper busbar, the PCB circuit board is connected to a heat sink provided on the other side of the power module, and a DSP controller, a drive circuit, a sampling circuit, a protection circuit, an auxiliary power supply circuit, and a communication circuit are provided on the PCB circuit board;

[0008] The PCB circuit board is provided with a current amplification circuit connected to the driving circuit. The current amplification circuit includes a first branch and a second branch set at the OUTH pin of the driving circuit, and a third branch and a fourth branch set at the OUTL pin of the driving circuit. The first branch is provided with a first regulating resistor R1 mounting position, and the second branch is provided with an output regulating resistor R2 and a first power switch Q1 in sequence.

[0009] The third branch is provided with a second control resistor R3 mounting position, and the fourth branch is provided with an input control resistor R4 and a second power switch in sequence; the first power switch and the second power switch are connected in sequence with a third control resistor R5 and a fourth control resistor R6; the first control resistor R1 mounting position and the second control resistor R3 mounting position are connected by a trace, and the gate wiring is connected in sequence to the middle of the trace, the middle of the connecting line between the third control resistor R5 and the fourth control resistor R6, and the gate interface GATE.

[0010] The output terminal of the second power switch is provided with a negative power interface VEE. The output terminal of the second power switch Q2 is also connected to a first capacitor C4. The two ends of the first capacitor C4 are connected in parallel to a second capacitor C3. The other ends of the first capacitor C4 and the second capacitor C3 are grounded. The input terminal of the first power switch is provided with a positive power interface VDD. The input terminal of the first power switch is also connected to a third capacitor C1. The two ends of the third capacitor C1 are connected in parallel to a fourth capacitor C2. The other ends of the third capacitor C1 and the fourth capacitor C2 are grounded.

[0011] As a preferred embodiment, a layer of thermally conductive silicone grease is provided between the heat sink and the power module.

[0012] As a preferred embodiment, the power module is a SiC power module.

[0013] As a preferred embodiment, the heat sink is an air-cooled heat sink, and the PCB circuit board is equipped with several cooling fans.

[0014] As a preferred embodiment, the current sensor is a Hall current sensor.

[0015] As a preferred embodiment, the radiator is an aluminum air-cooled radiator, and the radiator fins are equipped with heat dissipation copper pipes.

[0016] The beneficial effects of this invention are:

[0017] This inverter integrates control, drive, sampling, protection, communication, and auxiliary power supply onto a single PCB. Real-time monitoring and fault diagnosis are achieved through an embedded chip, reducing the use of connecting cables and connectors and improving system integration and reliability. Drive signals are directly connected to the SiC module via the PCB, shortening drive signal trace length and reducing interference. The DSP controller integrates EtherCAT peripherals, enabling direct communication with the PLC without requiring a separate slave DSP controller, simplifying system design. The drive chip integrates overcurrent protection and isolated analog-to-digital conversion functions, simplifying circuit design. This inverter features high integration, a small size, and is suitable for space constraints on ships. Air cooling simplifies the structure and reduces maintenance costs. The embedded chip collects circuit information for real-time monitoring and fault diagnosis. The modular design facilitates production and maintenance.

[0018] To improve driving capability and adapt to SiC modules of different power levels, a current amplifier stage was added outside the driving circuit. The magnitude of the driving current determines the switching speed of the power module, and thus the switching losses. Insufficient driving current results in slow switching speed and high switching losses; excessive driving current leads to fast switching speed, oscillation, and increased switching stress. Since the optimal driving current cannot be determined before experimental debugging, designing redundant circuits greatly improves the flexibility of circuit debugging. Through this redundant design, users can freely switch between different driving circuits to adapt to different driving requirements, significantly improving the efficiency of design and debugging.

[0019] This inverter uses SiC power modules instead of traditional IGBT modules, optimizes the power circuit and drive circuit design, reduces losses, and meets the high-efficiency requirements of marine traction systems; optimizes the layout between power devices, DC bus capacitors, and control circuit boards, reducing the use of connecting cables; and adopts air-cooling technology to simplify the heat dissipation structure, improve system reliability, and reduce design and manufacturing costs.

[0020] This inverter uses an aluminum heat sink with embedded copper pipes to improve heat dissipation efficiency. A layer of thermal grease is placed between the heat sink and the power modules to ensure that the heat from the power modules can be transferred to the heat sink evenly and efficiently. The heat sink is connected to the three power modules by bolts, ensuring the reliability of the connection and improving heat dissipation efficiency. Attached Figure Description

[0021] Figure 1 This is a front view of the inverter.

[0022] Figure 2 This is a diagram of the back structure of the inverter;

[0023] Figure 3 The results are from the thermal simulation of the power module.

[0024] Figure 4 A comparison chart of losses between SiC and IGBT;

[0025] Figure 5 A comparison chart of the efficiencies of SiC and IGBT;

[0026] Figure 6 This is a comparison chart of temperature rise between SiC and IGBT. Figure 7 This is a schematic diagram of the inverter's drive circuit. Detailed Implementation

[0027] The specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0028] like Figure 1-2 As shown, a marine traction inverter includes a PCB circuit board 4, on which several power modules 3 are mounted. The power modules 3 are SiC power modules. An input copper busbar 1 is connected to the input side of each power module 3, and an output copper busbar 7 is connected to the output side. Three input DC bus capacitors 2 are mounted on the input copper busbar 7, and a Hall current sensor 8 is connected to the output copper busbar. The PCB circuit board 4 is connected to a heat sink 5 located on the other side of the power modules 3, with a layer of thermally conductive silicone grease between the heat sink 5 and the power modules 3. The heat sink 5 is an aluminum air-cooled heat sink, and the heat sink fins contain internal copper heat pipes. Several cooling fans 6 are mounted on the PCB circuit board 4. The cooling fans 6 are placed on one side of the heat sink, and their speed can be controlled by real-time monitoring of the module temperature to achieve intelligent cooling.

[0029] The PCB circuit board 4 is equipped with a DSP controller, drive circuit, sampling circuit, protection circuit, auxiliary power supply circuit, and communication circuit;

[0030] like Figure 7 As shown, the PCB circuit board 4 is provided with a current amplification circuit connected to the driving circuit. The current amplification circuit includes a first branch and a second branch set at the OUTH pin of the driving circuit, and a third branch and a fourth branch set at the OUTL pin of the driving circuit. The first branch is provided with a first regulating resistor R1 mounting position, and the second branch is provided with an output regulating resistor R2 and a first power switch Q1 in sequence.

[0031] A second regulating resistor R3 mounting position is arranged on the third branch, and an input regulating resistor R4 and a second power switch are sequentially arranged on the fourth branch; a third regulating resistor R5 and a fourth regulating resistor R6 are sequentially connected between the first power switch and the second power switch, the first regulating resistor R1 mounting position and the second regulating resistor R3 mounting position are communicated through a trace, and the gate wiring is sequentially connected to the middle part of the trace, the middle part of the connecting line between the third regulating resistor R5 and the fourth regulating resistor R6, and the gate interface GATE;

[0032] A power negative interface VEE is arranged at the output pole of the second power switch, a first capacitor C4 is further connected to the output pole of the second power switch Q2, a second capacitor C3 is connected in parallel across the first capacitor C4, and the other ends of the first capacitor C4 and the second capacitor C3 are grounded; a power positive interface VDD is arranged at the input pole of the first power switch; a third capacitor C1 is further connected to the input pole of the first power switch, a fourth capacitor C2 is connected in parallel across the third capacitor C1, and the other ends of the third capacitor C1 and the fourth capacitor C2 are grounded.

[0033] Assuming that the maximum drive current that the drive chip can output is Ichip, and the drive current required by the power module is Idrive, when Ichip>Idrive, the drive chip is used to directly output the drive current, at this time R1 and R3 are soldered, wherein R1 controls the turn-on current and R3 controls the turn-off current; when Ichip<Idrive and the drive chip cannot meet the drive requirement, an external Current Buffer circuit is required for driving, in this case, R1 and R3 are not installed; at this time, R5 is used to control the turn-on current, and R6 is used to control the turn-off current.

[0034] This inverter optimizes the power circuit layout to shorten the power loop path, thereby reducing the parasitic resistance and parasitic inductance of the power loop. The input-side copper bars connect three film capacitors in parallel, so that the film capacitors are as close as possible to the input port of the power module to reduce the power loop inductance; in addition, under the condition of ensuring the insulation distance, the distance between the two input copper bars (positive input and negative input) is minimized, and the two input copper bars are arranged to face each other, which can realize reverse coupling between the two parasitic inductances and further reduce the power loop inductance.

[0035] This inverter integrates the DSP controller, drive circuit, sampling circuit, protection circuit, auxiliary power supply circuit, and EtherCAT communication circuit on one PCB, reducing the use of connectors and connecting cables. The PCB is directly connected to the drive interface of the power module, which greatly shortens the drive loop path, reduces the parasitic inductance of the drive loop, and ensures efficient and stable driving of the power module.

[0036] The experimental sample inverter was designed with the following parameters: rated input DC voltage 800Vdc, rated output AC voltage 400Vac (line voltage), rated output AC current 288A, overload current 345.6A (60s), rated power 200kW, and rated frequency 50Hz. A thermal simulation model was built in Flotherm, and the simulated temperature of the inverter operating at 10kHz and 240kW output was obtained as follows: Figure 3 As shown, the chip junction temperature is approximately 115°C, which is within the safe operating range.

[0037] The inverter has a high output power, and to achieve air cooling, the power module losses must be reduced. Therefore, SiC power modules are used instead of traditional IGBT power modules. The losses, efficiency, and temperature rise of SiC and IGBT power modules at a 10kHz switching frequency were calculated and compared, as shown below. Figures 4-6 As shown, compared to IGBT modules, SiC modules exhibit lower losses, higher efficiency, and lower temperature rise.

[0038] Traditional IGBT modules have high losses and require water cooling to ensure their reliability. However, this inverter uses SiC power modules, which greatly reduces module losses and makes air cooling possible, significantly reducing system cost and complexity.

[0039] This inverter can use the F2838x series DSP controller, which has abundant PWM channels and ADC channels, and integrates an EtherCAT slave DSP controller. This allows it to acquire real-time information such as voltage, current, and temperature from the inverter and interact with the PLC host via EtherCAT communication. Inverters based on this embedded chip greatly simplify circuit design, improve system reliability, and reduce system costs.

[0040] The above embodiments are merely illustrative of the principles and effects of the present invention, as well as some examples of its application, and are not intended to limit the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the inventive concept of the present invention, and these modifications and improvements are all within the scope of protection of the present invention.

Claims

1. A ship traction inverter, comprising a PCB circuit board (4), wherein a plurality of power modules (3) are disposed on the PCB circuit board (4), characterized in that: The power module (3) has an input copper busbar (1) connected to its input side and an output copper busbar (7) connected to its output side. The input copper busbar (7) is provided with several input DC bus capacitors (2), and the output copper busbar (7) is connected with a current sensor (8). The PCB circuit board (4) is connected to a heat sink (5) located on the other side of the power module (3). The PCB circuit board (4) is provided with a DSP controller, a drive circuit, a sampling circuit, a protection circuit, an auxiliary power supply circuit, and a communication circuit. The PCB circuit board (4) is provided with a current amplification circuit connected to the driving circuit. The current amplification circuit includes a first branch and a second branch set at the OUTH pin of the driving circuit, and a third branch and a fourth branch set at the OUTL pin of the driving circuit. The first branch is provided with a first regulating resistor R1 mounting position, the second branch is provided with an output regulating resistor R2 and a first power switch Q1 in sequence; the third branch is provided with a second regulating resistor R3 mounting position, and the fourth branch is provided with an input regulating resistor R4 and a second power switch in sequence. A third regulating resistor R5 and a fourth regulating resistor R6 are connected sequentially between the first power switch and the second power switch. The mounting position of the first regulating resistor R1 and the mounting position of the second regulating resistor R3 are connected by a trace. The gate wiring is connected sequentially to the middle of the trace, the middle of the connecting line between the third regulating resistor R5 and the fourth regulating resistor R6, and the gate interface GATE. The output terminal of the second power switch is provided with a negative power interface VEE. The output terminal of the second power switch Q2 is also connected to a first capacitor C4. The two ends of the first capacitor C4 are connected in parallel to a second capacitor C3. The other ends of the first capacitor C4 and the second capacitor C3 are grounded. The input terminal of the first power switch is provided with a positive power interface VDD. The input terminal of the first power switch is also connected to a third capacitor C1. The two ends of the third capacitor C1 are connected in parallel to a fourth capacitor C2. The other ends of the third capacitor C1 and the fourth capacitor C2 are grounded.

2. A ship traction inverter as described in claim 1, characterized in that... A layer of thermally conductive silicone grease is provided between the heat sink (5) and the power module (3).

3. A ship traction inverter as described in claim 1, characterized in that... The power module (3) is a SiC power module.

4. A ship traction inverter as described in claim 1, characterized in that... The heat sink (5) is an air-cooled heat sink, and the PCB circuit board (4) is provided with several cooling fans (6).

5. A ship traction inverter as described in claim 1, characterized in that... The current sensor (8) is a Hall current sensor.

6. A ship traction inverter as described in claim 4, characterized in that... The radiator (5) is an aluminum air-cooled radiator, and the heat sink is equipped with a heat dissipation copper pipe.

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