Three-phase voltage converter for an unmanned vehicle

Abstract

The invention relates to the field of electrical engineering, and more particularly to converter equipment with high levels of protection against various effects present in a moving highly-automated unmanned vehicle. A three-phase voltage converter comprises power switches disposed inside a moisture-proof housing and consisting of high-frequency silicon carbide-based field-effect transistors soldered to a power board in a specific manner to allow heat to be dissipated directly to the surface of the housing, chokes and capacitors, universal control system boards with built-in circuit parameter meters, and a CAN interface for exchanging data with a top-level device. The result is a reduction in the overall weight and dimensions of the article, an increase in conversion frequency, a low level of electromagnetic interference, effective heat dissipation, and high resistance to mechanical effects.

Description

Description of the invention THREE-PHASE VOLTAGE CONVERTER FOR UNMANNED VEHICLE Field of technology to which the invention relates

[0001] The invention relates to the field of electrical engineering, namely to converter technology with high degrees of protection against various impacts that are present in a moving unmanned highly automated vehicle (HEV), more specifically to DC-AC converters for converting the voltage of the traction battery of an unmanned highly automated vehicle into a three-phase 0.4 kV network for powering a three-phase motor of an on-board compressor or pump with provision of soft start functions, control of a relief valve, protection of the supply line of the electric motor, windings of the electric motor, parts of the compressor or pump from oil starvation. State of the art

[0002] The state of the art includes a large number of different types of DC-AC converters with different topologies, circuitry and technical solutions that provide different special levels of protection in difficult conditions of converter use. The solution to create a specialized DC-AC converter, by means of which the operation of low-current on-board consumers in ATS is maintained, has a number of advantages over analogues.

[0003] A three-phase complex-bridge voltage inverter is known for converting direct voltage into three-phase alternating voltage (RU 110880 Ul, H02M 7 / 48, published 27.11.2011), containing two three-phase bridge inverters, the power inputs of which are connected to a common source of direct voltage, and the outputs of alternating current are connected respectively to the primary windings of two three-phase transformers connected in triangles, and comprises a third three-phase transformer and a third three-phase bridge voltage inverter, wherein the inputs of direct current of the three-phase bridge inverter are connected to a common source of direct voltage, and the outputs of alternating current are connected to the primary windings of the third three-phase transformer connected in a star, wherein the transformers, the primary windings of which are connected in a triangle, have secondary windings connected in phase in line-series with each other and in phase in opposite-series with the secondary windings of the transformer, the primary winding of which is connected in a star.

[0004] The disadvantages of this technical solution are the use of a large number of power semiconductor devices and winding elements, which complicates the control system, reduces the conversion frequency and increases the weight and dimensions of both individual components and the entire device as a whole, as a result of which the device has limited application in transport, namely in conditions of transport impacts arising on the frame of a moving wheeled vehicle on public roads.

[0005] A converter of direct current into alternating sinusoidal voltage is known (RU 2402146 Cl, H02M 7 / 501, published 20.10.2010), adopted as a prototype and containing a master oscillator, the output of which is connected to the input of a frequency divider, the outputs of which are connected to the anodes of diodes, the cathodes of which are connected to the gates of MOSFET transistors, the drains of which are connected to the terminals of the primary winding of the power output transformer, the middle tap of which is connected to the positive pole of the power source, and the output of the generator is connected to a frequency divider consisting of two binary counters, two decoders / demultiplexers, the first and second diodes and a transistor inverter, wherein the outputs of one of the counters are connected to the address inputs of the decoders / demultiplexers, the control input of the first decoder / demultiplexer is connected to the output of the least significant digit of the second binary counter, the control input of the second decoder / demultiplexer is connected to the output of the transistor inverter, the input of which is connected to the output of the least significant digit of the second binary counter, the input of the second binary counter is connected to the cathodes of the first and second diodes, the anodes of which are connected to the outputs of the maximum digits of the first and second decoders / demultiplexers, respectively, the anodes of the diodes are also connected to the outputs of the decoders / demultiplexers, the cathodes of which are connected to the gates of the MOSFET transistors, in addition, the transformer contains additional taps in each half-winding of the primary winding of the power output transformer, which are connected to the drains MOSFET transistors.

[0006] The disadvantages of this technical solution are the presence of a large number of power keys, which complicates the cooling system, the impossibility of creating low levels of alternating voltages without significant distortion of the output voltage shape, which also requires additional measures to reduce electromagnetic interference from the operation of the converter. Disclosure of the essence of the invention

[0007] The task solved by the proposed technical solution is to create a DC-AC voltage converter with key protection and load protection for an unmanned highly automated electric freight vehicle, namely for controlling and powering an on-board three-phase electric motor of a compressor or pump of an unmanned ATS, which is capable of withstanding the impacts that occur on the frame of a moving wheeled vehicle.

[0008] The technical result of the claimed invention is the improvement of the consumer qualities of the device by reducing the weight and dimensions of the product and providing the required functionality, which, in turn, is achieved by increasing the conversion frequency, without using complex conversion and protection circuits, while simultaneously ensuring a low level of electromagnetic interference and a special design of the structure, which provides effective heat dissipation and high resistance to mechanical impacts.

[0009] The claimed technical result is achieved using the claimed three-phase voltage converter for unmanned highly automated vehicles, containing power keys located inside a moisture-proof housing, which are high-frequency power field-effect transistors based on silicon carbide (SiC), which, in turn, are soldered with their heat sink (drain) to the through metallization of the power board and through an insulating ceramic substrate made of aluminum nitride with copper sputtering soldered to the board from the back side provide heat removal directly to the surface of one of the sides of the moisture-proof housing, which is a heat exchange radiator that ensures any spatial orientation of the housing, in addition, chokes and capacitors are installed inside the moisture-proof housing, which form a three-phase sinusoidal output LC filter, which, in turn,generates a sinusoidal voltage at the converter output and ensures a low level of higher harmonics of the output voltage relative to the first harmonic and, accordingly, a low level of electromagnetic interference in the circuits of the output load and wires, and universal control system boards that allow scaling the power of the device, with built-in circuit parameter meters (input / output current, input / output voltage, key temperature meters, etc.) winding components) and a CAN interface for data exchange with a higher-level device.

[0010] The technical solutions used in this control system allow monitoring and tracking the main parameters of the state of each power element of the converter, providing the required modes of starting the compressor or pump, with preliminary unloading of the discharge line and a stabilized power supply level to provide a three-phase sinusoidal voltage to the load at the converter output, which is a three-phase asynchronous electric motor of the compressor or pump in the V ATS. The technical solutions used for the winding components and the design of the heat pipe allow efficient heat removal from the converter elements, simultaneously providing high degrees of protection from atmospheric influences, chemical influences and mechanical influences in the form of vibration. Brief description of the drawings [OOP] Fig. 1 shows a functional diagram of a three-phase converter, where: 1 - battery; 2 - source of own needs; 3 - input choke; 4 - output chokes; 5 - input capacitor; 6 - output capacitors; 7 - power transistors; 8 - output current sensors; 9 - temperature sensors; 10 - driver board; 11 - control board; 12 - load.

[0012] Fig. 2 shows the method of fastening transistors inside the converter housing, where: 13 - power transistor housing; 14 - dielectric substrates.

[0013] This converter uses silicon carbide surface-mount transistors. They are soldered to the top of the power board. To achieve sufficient heat dissipation from the power transistors, dielectric substrates made of aluminum nitride with copper sputtering on one side were used (Fig. 2).

[0014] Fig. 3 shows dielectric substrates made of aluminum nitride with copper sputtering.

[0015] This material has high dielectric and operational properties, and the copper coating allows these substrates to be soldered directly to the copper polygon on the bottom side of the board, which is connected by heat-conducting vias to the top side (Fig. 3).

[0016] Fig. 4 shows the substrates soldered onto the copper polygon on the bottom side of the board. Implementation of the invention

[0017] DC-AC converter is a device that converts input DC voltage in the range from 550 to 800 V into three-phase AC output voltage in the range from 0 to 400 V with a frequency from 0 to 50 Hz in accordance with the linear control method of an asynchronous electric motor U / F=const.

[0018] The supply voltage is supplied to the converter input from the battery (1). The auxiliary power source (2) supplies power to the driver board (10) and the control board (11). The control board (11) generates rectangular control pulses to form three-phase sinusoidal voltages shifted between themselves by 120 degrees for power transistors (7). Driver board (10) amplifies control pulses by current and voltage, which are fed to the gates of transistors, relative to sources. Input choke (3) and input capacitor (5) form an input L-shaped filter to reduce pulsations in input voltage. Power transistors (7) convert direct voltage into high-frequency alternating voltage, which is fed to the input of LC filter, which is formed by output chokes (4) and output capacitors (6). LC filter smoothes the output voltage, after which it has a shape very close to ideal sinusoidal. Output current sensors (8) generate signals about the converter output current and, accordingly, the state of the load (12). Temperature sensors (9) generate signals about the temperature of power transistors (7).

[0019] The absence of other components on one side of the power board, except for the dielectric substrates (14), allows for thermal contact between the substrates and the radiator, thereby implementing effective heat exchange between the crystals of the power transistors (7) through the case of the power transistor (13) and the environment. This approach is more technologically advanced in terms of mass production and more effective in heat transfer than the conventional method of attaching transistors to a radiator.

[0020] In addition, the cooling method described above allows for improving the weight, size and performance characteristics of the converter, and the use of silicon carbide transistors increases the efficiency of the entire device.

[0021] The use of a universal control system (driver board and control board) allows scaling the power and functionality of the base device.

[0022] Communication with higher-level devices is carried out via the CAN interface, which is a reliable data exchange protocol for automotive applications.

[0023] The case of this device is made in a moisture-proof case made of aluminum, according to the IP-67 standard. This is ensured by the cover, which is fixed with screws to the walls of the case, and a rubber cord is laid along its perimeter, preventing moisture from getting inside. Also, special moisture-proof connectors are installed on the case.

[0024] Air cooling allows any spatial orientation of the unit, which adds flexibility in placement on vehicles.

[0025] The claimed technical solution meets the requirement of industrial applicability and can be implemented on any ground-based unmanned aerial vehicles.

Claims

Invention formula A three-phase voltage converter for unmanned highly automated vehicles, containing power keys located inside a moisture-proof housing, which are high-frequency power field-effect transistors based on silicon carbide (SiC), which, in turn, are soldered with their heat sink (drain) to the through metallization of the power board and through an insulating ceramic substrate made of aluminum nitride with copper sputtering soldered to the board from the back side provide heat removal directly to the surface of one of the sides of the moisture-proof housing, which is a heat exchange radiator providing any spatial orientation of the housing, in addition, chokes and capacitors are installed inside the moisture-proof housing, which form a three-phase sinusoidal output LC filter, which, in turn, forms a sinusoidal voltage at the converter output, and universal control system boards,allowing scaling of the device power, with built-in circuit parameter meters (input / output current, input / output voltage, temperature meters for keys and winding components) and a CAN interface for data exchange with the upper-level device.

Images